Curcumin Derived from Turmeric Curcuma longa ): a Spice for All Seasons

Curcumin Derived from
23 Turmeric (Curcuma longa):
a Spice for All Seasons
Bharat B. Aggarwal, Anushree Kumar, Manoj S. Aggarwal,
and Shishir Shishodia
CONTENTS
23.1 Introduction...........................................................................................................................350
23.2 Anticancer Properties of Curcumin .....................................................................................351
23.2.1
Curcumin Inhibits Tumorigenesis........................................................................351
23.2.2
Curcumin Exhibits Antiproliferative Effects against Cancer Cells.....................352
23.2.3
Curcumin Down-Regulates the Activity of Epidermal Growth
Factor Receptor (EGFR) and Expression of HER2/neu .....................................353
23.2.4
Curcumin Down-Regulates the Activation of Nuclear
Factor-kb (Nf-kb).................................................................................................354
23.2.5
Curcumin Down-Regulates the Activation of STAT3 Pathway ..........................354
23.2.6
Curcumin Activates Peroxisome Proliferator-Activated
Receptor-g (PPAR-g) ............................................................................................355
23.2.7
Curcumin Down-Regulates the Activation of Activator
Protein-1 (AP-1) and C-Jun N-Terminal Kinase (JNK) .....................................355
23.2.8
Curcumin Suppresses the Induction of Adhesion Molecules .............................355
23.2.9
Curcumin Down-Regulates Cyclooxygenase-2 (COX-2) Expression ................355
23.2.10
Curcumin Inhibits Angiogenesis..........................................................................356
23.2.11
Curcumin Suppresses the Expression of MMP9 and Inducible
Nitric Oxide Synthase (INOS).............................................................................356
23.2.12
Curcumin Down-Regulates Cyclin D1 Expression .............................................356
23.2.13
Curcumin Is Chemopreventive ............................................................................356
23.2.14
Curcumin Inhibits Tumor Growth and Metastasis in Animals ...........................357
23.2.15
Curcumin Inhibits Androgen Receptors and AR-Related
Cofactors ..............................................................................................................358
23.3 Effect of Curcumin on Atherosclerosis and Myocardial Infarction ....................................359
23.3.1
Curcumin Inhibits the Proliferation of Vascular Smooth
Muscle Cells.........................................................................................................359
23.3.2
Curcumin Lowers Serum Cholesterol Levels......................................................360
23.3.3
Curcumin Inhibits LDL Oxidation ......................................................................361
23.3.4
Curcumin Inhibits Platelet Aggregation ..............................................................362
23.3.5
Curcumin Inhibits Myocardial Infarction............................................................362
23.4 Other Effect of Curcumin ....................................................................................................363
23.4.1
Curcumin Suppresses Diabetes............................................................................363
23.4.2
Curcumin Stimulates Muscle Regeneration ........................................................364
0-8493-1560-3/05/$0.00+$1.50
349
© 2005 by CRC Press LLC

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23.4.3
Curcumin Enhances Wound Healing ...................................................................365
23.4.4
Curcumin Suppresses Symptoms Associated with Arthritis ...............................365
23.4.5
Curcumin Reduces the Incidence of Cholesterol
Gallstone Formation.............................................................................................366
23.4.6
Curcumin Modulates Multiple Sclerosis .............................................................366
23.4.7
Curcumin Blocks the Replication of HIV...........................................................367
23.4.8
Curcumin Affects Alzheimer’s Disease ...............................................................367
23.4.9
Curcumin Protects against Cataract Formation...................................................368
23.4.10
Curcumin Protects from Drug-Induced Myocardial Toxicity .............................368
23.4.11
Curcumin Protects from Alcohol-Induced Liver Injury ......................................368
23.4.12
Curcumin Protects from Drug-Induced Lung Injury ..........................................369
23.4.13
Curcumin Prevents Adriamycin-Induced Nephrotoxicity ...................................371
23.4.14
Curcumin Protects from Scarring ........................................................................371
23.4.15
Curcumin Protects from Inflammatory Bowel Disease.......................................371
23.4.16
Curcumin Enhances the Immunosuppressive Activity
of Cyclosporine ....................................................................................................372
23.4.17
Curcumin Protects against Various Forms of Stress ...........................................372
23.4.18
Curcumin Protects against Endotoxin Shock ......................................................372
23.4.19
Curcumin Protects against Pancreatitis ...............................................................372
23.4.20
Curcumin Inhibits Multidrug Resistance (MDR)................................................372
23.5 Curcumin Metabolism ..........................................................................................................373
23.6 Clinical Experience with Curcumin.....................................................................................374
23.7 Curcumin Analogs ................................................................................................................376
23.8 Sources of Curcumin............................................................................................................377
23.9 Conclusion ............................................................................................................................378
Acknowledgment............................................................................................................................379
References ......................................................................................................................................379
23.1 INTRODUCTION
Curcuma longa or turmeric is a tropical plant native to southern and southeastern tropical Asia.
A perennial herb belonging to the ginger family, turmeric measures up to 1 m high with a short
stem and tufted leaves (Figure 23.1A). The parts used are the rhizomes. Perhaps the most active
component in turmeric is curcumin, which may make up 2 to 5% of the total spice in turmeric
(Figure 23.1B). Curcumin is a diferuloylmethane present in extracts of the plant. Curcuminoids
are responsible for the yellow color of turmeric and curry powder. They are derived from turmeric
by ethanol extraction. The pure orange-yellow, crystalline powder is insoluble in water. The
structure of curcumin (C H O ) was first described in 1815 by Vogel and Pellatier and in 1910
21
20
6
was shown to be diferuloylmethane by Lampe et al. [1]. Chemical synthesis in 1913 confirmed
its identity [2].
Turmeric is widely consumed in the countries of its origin for a variety of uses, including as
a dietary spice, a dietary pigment, and an Indian folk medicine for the treatment of various illnesses.
It is used in the textile and pharmaceutical industries [3] and in Hindu religious ceremonies in one
form or another. Current traditional Indian medicine uses it for biliary disorders, anorexia, cough,
diabetic wounds, hepatic disorders, rheumatism, and sinusitis [4]. The old Hindu texts have
described it as an aromatic stimulant and carminative [5]. Powder of turmeric mixed with slaked
lime is a household remedy for the treatment of sprains and swelling caused by injury, applied
locally over the affected area. In some parts of India, the powder is taken orally for the treatment
of sore throat. This nonnutritive phytochemical is pharmacologically safe, considering that it has
been consumed as a dietary spice, at doses up to 100 mg/day, for centuries [6]. Recent phase I

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Curcumin Derived from Turmeric (Curcuma longa): a Spice for All Seasons
351
O O
CH3O
OCH3
Curcumin I
(77%)
HO
OH
O O
Curcumin II
OCH3
Demethoxycurcumin
(17%)
HO
OH
t.s. of rhizome
O O
Curcumin III
Bis-Demethoxycurcumin
plant
OH
HO
(3%; less active)
rhizome
A
B
FIGURE 23.1 The plant Curcuma longa (panel A), from which curcumin is derived, and its structure
(panel B).
clinical trials indicate that people can tolerate a dose as high as 8 g/day [7]. In the U.S., curcumin
is used as a coloring agent in cheese, spices, mustard, cereals, pickles, potato flakes, soups, ice-
creams, and yogurts (www.kalsec.com).
Curcumin is not water-soluble, but it is soluble in ethanol or in dimethylsulfoxide. The
degradation kinetics of curcumin under various pH conditions and the stability of curcumin in
physiological matrices have been established [8]. When curcumin was incubated in 0.1M phosphate
buffer and serum-free medium (pH 7.2 at 37∞C), about 90% decomposed within 30 min. A series
of pH conditions ranging from 3 to 10 were tested, and the results showed that decomposition
was pH-dependent and occurred faster at neutral-basic conditions. It is more stable in cell culture
medium containing 10% fetal calf serum and in human blood. Less than 20% of curcumin
decomposed within 1 h, and after incubation for 8 h, about 50% of curcumin still remained. Trans-
6-(4¢-hydroxy-3¢-methoxyphenyl)-2,4-dioxo-5-hexenal was predicted to be the major degradation
product, and vanillin, ferulic acid, and feruloyl methane were identified as minor degradation
products. The amount of vanillin increased with incubation time.
Numerous studies have indicated that curcumin has antioxidant and anti-inflammatory prop-
erties. A Medline search revealed over 1000 publications describing various activities of this
polyphenol. The following sections describe some of its major biological and clinical effects.
23.2 ANTICANCER PROPERTIES OF CURCUMIN
23.2.1 CURCUMIN INHIBITS TUMORIGENESIS
Numerous reports suggest that curcumin has chemopreventive and chemotherapeutic effects (Figure
23.2). Its anticancer potential in various systems was recently reviewed by our laboratory [9].
Curcumin blocks tumor initiation induced by benzo[a]pyrene and 7,12dimethylbenz[a]anthracene

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Phytopharmaceuticals in Cancer Chemoprevention
Overexpression:
Overexpression:
Constitutive activation of
Oncogenes
transcription factors
Matrix metalloproteases
HER2
Cyclooxygenase-2
STAT3, AP-1& NF-kB
Growth factors
Adhesion molecules
(e.g; EGF, PDGF, FGF)
Chemokines
Growth factor receptors
Tumor Suppressor genes
TNF
Survival factors
(e.g; Survivin, Bcl-2 and Bcl-x1)
Cyclin D1
Decoy receptor
Transformation
Proliferation
Invasion
Normal
Tumor
Tumor
Tumor
cells
cells
growth
Metastasis
curcumin
FIGURE 23.2 Various steps involved in tumorigenesis and metastasis and their suppression by curcumin.
[10], and it suppresses phorbol ester-induced tumor promotion [11, 12]. In vivo, curcumin was
found to suppress carcinogenesis of the skin [12–15], the forestomach [16, 17], the colon [18–20],
and the liver [21] in mice. Curcumin also suppresses mammary carcinogenesis [22–24].
23.2.2 CURCUMIN EXHIBITS ANTIPROLIFERATIVE EFFECTS AGAINST CANCER CELLS
Compounds that block or suppress the proliferation of tumor cells have potential as anticancer
agents. Curcumin has been shown to inhibit the proliferation of a wide variety of tumor cells,
including B-cell and T-cell leukemia [25–28], colon carcinoma [29], and epidermoid carcinoma
cells [30]. It has also been shown to suppress the proliferation of various breast carcinoma cell
lines in culture [31–33]. We showed that the growth of the breast tumor cell lines BT20, SKBR3,
MCF-7, T47D, and ZR75-1 is completely inhibited by curcumin, as indicated by MTT dye uptake,
[3H] thymidine incorporation, and clonogenic assay [31]. We also showed that curcumin can
overcome Adriamycin resistance in MCF-7 cells [31]. Recently, we have shown that curcumin can
activate caspase-8, which leads to cleavage of Bid, thus resulting in sequential release of mitochon-
drial cytochrome C and activation of caspase-9 and caspase-3 [34]. More recently, we have dem-
onstrated that curcumin can suppress the proliferation of multiple myeloma cells [35]. Woo et al.
[36] have demonstrated that curcumin can cause cell damage by inactivating the Akt-related cell
survival pathway and release of cytochrome c, providing a new mechanism for curcumin-induced
cytotoxicity.
Zheng et al. [37] explored the apoptosis-inducing effects of curcumin in human ovarian tumor
A2780 cells. They found that curcumin could significantly inhibit the growth of ovarian cancer
cells by inducing apoptosis through up-regulation of caspase-3 and down-regulation of expression
of NF-kB. Studies have also been performed to examine the synergy of curcumin with other
antiproliferative agents. Deeb et al. [38] investigated whether curcumin and TNF-related apoptosis-
inducing ligand (TRAIL) cooperatively interact to promote death of LNCaP cells. At concentra-
tions at which neither of the two agents alone produced significant cytotoxicity in LNCaP cells,
cell death was markedly enhanced (two- to three-fold) if tumor cells were treated with curcumin
and TRAIL together. The combined curcumin and TRAIL treatment increased the number of
hypodiploid cells and induced DNA fragmentation in LNCaP cells. The combined treatment
induced cleavage of procaspase-3, procaspase-8, and procaspase-9, truncation of BID, and release

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Curcumin Derived from Turmeric (Curcuma longa): a Spice for All Seasons
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Cyclin D1↓
5-LOX ↓
COX2 ↓
iNOS ↓
MMP9 ↓
IL-8 ↓
IL-6 ↓
TNF ↓
IL-12 ↓
Gene expression
IKK ↓
NF-κB ↓
EGFR ↓
AP-1 ↓
HER2 ↓
Egr-1 ↓
AKT ↓
STAT1 ↓
Src ↓
STAT3 ↓
Protein
Curcumin
Transcription
JAK2
kinases
↓
factors
STAT5
TYK2 ↓
PPARg ↑
EpRE
JNK ↓
↓
CBP ↓
PKA ↓
β-catenin ↑
PKC ↓
Others
Enzymes
Nrf2 ↑
VCAM-1 ↓
Bcl-2 ↓
Bcl-x1 ↓ ICAM-1 ↓
FTPase ↓
GST ↑
GSH-px
TF ↓
AR/ARP ↓
P53 ↑
MDR ↓
ELAM-1 ↓
Hemeoxygenase ↑
Xanthine oxidase ↓
uPA ↓
FIGURE 23.3 Molecular targets shown to be regulated by curcumin.
of cytochrome c from the mitochondria, indicating that both the extrinsic (receptor mediated) and
intrinsic (chemical induced) pathways of apoptosis are triggered in prostate cancer cells treated
with a combination of curcumin and TRAIL. These results define a potential use of curcumin to
sensitize prostate cancer cells for TRAIL-mediated immunotherapy.
Chan et al. [39] demonstrated that curcumin increased the sensitivity of ovarian cancer cells
(CAOV3 and SKOV3) to cisplatin. The effect was obtained both when the compound was added
simultaneously with cisplatin and when it was added 24 h before. Curcumin inhibited the production
of interleukin 6 (IL-6) in these cell lines (Figure 23.3), suggesting that one of the mechanisms for
synergy between cisplatin and curcumin involved reducing the autologous production of IL-6.
However, the synergy was also observed in the low IL-6 producer, SKOV3, indicating that additional
targets were responsible. The down-regulation of IL-6 by curcumin was also noted in multiple
myeloma cells [35].
23.2.3 CURCUMIN DOWN-REGULATES THE ACTIVITY OF EPIDERMAL GROWTH
FACTOR RECEPTOR (EGFR) AND EXPRESSION OF HER2/NEU
HER2/neu and epithelial growth factor receptor (EGFR) activity represent one possible mechanism
by which curcumin suppresses the growth of breast cancer cells. Almost 30% of the breast cancer
cases have been shown to overexpress the HER2/neu protooncogene [40], and both HER2 and EGF
receptors stimulate proliferation of breast cancer cells. Overexpression of these two proteins cor-
relates with progression of human breast cancer and poor patient prognosis [40]. Curcumin has
been shown to down-regulate the activity of EGFR and HER2/neu [30, 41] and to deplete the cells
of HER2/neu protein [42]. Additionally, we have recently found that curcumin can down-regulate
bcl-2 expression, which may contribute to its antiproliferative activity [43].

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Like geldanamycin, curcumin has been shown to provoke the intracellular degradation of HER2
[44]. HER2 mutations, however, limit the capacity of geldanamycin to disrupt the tyrosine kinase
activity of HER2. Thus these HER2 mutants are resistant to geldanamycin-induced degradation,
but they maintain their sensitivity to curcumin through ErbB-2 degradation.
23.2.4 CURCUMIN DOWN-REGULATES THE ACTIVATION OF NUCLEAR
FACTOR-kB (NF-kB)
Curcumin may also operate through suppression of NF-kB activation (Figure 23.3). NF-kB is a
nuclear transcription factor required for the expression of genes involved in cell proliferation,
cell invasion, metastasis, angiogenesis, and resistance to chemotherapy [45]. This factor is
activated in response to inflammatory stimuli, carcinogens, tumor promoters, and hypoxia, which
is frequently encountered in tumor tissues [46]. Several groups, including ours, have shown that
activated NF-kB suppresses apoptosis in a wide variety of tumor cells [47–49], and it has been
implicated in chemoresistance [47]. We have shown that cells that overexpress NF-kB are resistant
to paclitaxel-induced apoptosis [50]. Furthermore, the constitutively active form of NF-kB has
been reported in human breast cancer cell lines in culture [51], carcinogen-induced mouse
mammary tumors [52], and biopsies from patients with breast cancer [53]. Our laboratory has
shown that various tumor promoters, including phorbol ester, TNF, and H O , activate NF-kB
2
2
and that curcumin down-regulates the activation [54]. Subsequently, others showed that curcumin-
induced down-regulation of NF-kB is mediated through suppression of IkBa kinase activation
[55, 56]. Recently, Shishodia et al. [57] have shown that curcumin down-regulated cigarette
smoke-induced NF-kB activation through inhibition of IkBa kinase in human lung epithelial
cells. This led to the down-regulation of cyclin D1, cyclooxygenase 1 (COX-2), and matrix
metalloproteinase 9 (MMP9) by curcumin. Philip et al. [58] have recently reported that curcumin
down-regulates osteopontin (OPN)-induced NF-kB-mediated promatrix metalloproteinase-2 acti-
vation through IkBa/IKK signaling.
23.2.5 CURCUMIN DOWN-REGULATES THE ACTIVATION OF STAT3 PATHWAY
Numerous reports suggest that IL-6 promotes survival and proliferation of various tumors, including
multiple myeloma (MM) cells, through the phosphorylation of a cell signaling protein, signal trans-
ducers, and activators of transcription (STAT3). Thus agents that suppress STAT3 phosphorylation
have potential for the treatment of MM. Bharti et al. [59] demonstrated that curcumin inhibited IL-
6-induced STAT3 phosphorylation and consequent STAT3 nuclear translocation. Curcumin had no
effect on STAT5 phosphorylation but inhibited the interferon a-induced STAT1 phosphorylation. The
constitutive phosphorylation of STAT3 found in certain MM cells was also abrogated by treatment
with curcumin. Curcumin-induced inhibition of STAT3 phosphorylation was reversible. Compared
with AG490, a well-characterized JAK2 inhibitor, curcumin was a more rapid (30 min vs. 8 h) and
more potent (10 mM vs. 100 mM) inhibitor of STAT3 phosphorylation. Similarly, at the dose of
curcumin that completely suppressed proliferation of MM cells, AG490 had no effect. In contrast,
the STAT3 inhibitor peptide that can inhibit the STAT3 phosphorylation mediated by Src blocked the
constitutive phosphorylation of STAT3 and also suppressed the growth of myeloma cells. TNF-a and
lymphotoxin (LT) also induced the proliferation of MM cells, but through a mechanism independent
of STAT3 phosphorylation. In addition, dexamethasone-resistant MM cells were found to be sensitive
to curcumin. Overall, these results demonstrated that curcumin was a potent inhibitor of STAT3
phosphorylation, and this plays a role in curcumin’s suppression of proliferation of MM.
Li et al. [60] showed that curcumin suppressed oncostatin-M-stimulated STAT1 phosphoryla-
tion, DNA-binding activity of STAT1, and c-Jun N-terminal kinase activation without affecting
Janus kinase 1 (JAK1), JAK2, JAK3, ERK1/2, and p38 phosphorylation. Curcumin also inhibited
OSM-induced MMP1, MMP3, MMP13, and TIMP3 gene expression.

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Curcumin Derived from Turmeric (Curcuma longa): a Spice for All Seasons
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Natarajan et al. [61] showed that treatment of activated T cells with curcumin inhibited IL-12-
induced tyrosine phosphorylation of Janus kinase 2, tyrosine kinase 2, and STAT3 and STAT4
transcription factors. The inhibition of the Janus kinase-STAT pathway by curcumin resulted in a
decrease in IL-12-induced T-cell proliferation and Th1 differentiation.
23.2.6 CURCUMIN ACTIVATES PEROXISOME PROLIFERATOR-ACTIVATED
RECEPTOR-g (PPAR-g)
Activation of PPAR-g inhibits the proliferation of nonadipocytes. The level of PPAR-g is dramat-
ically diminished along with activation of hepatic stellate cells (HSC). Xu et al. [62] demonstrated
that curcumin dramatically induced the gene expression of PPAR-g and activated PPAR-g in
activated HSC (Figure 23.3). Blocking its trans-activating activity by a PPAR-g antagonist markedly
decreased the effects of curcumin on inhibition of cell proliferation.
23.2.7 CURCUMIN DOWN-REGULATES THE ACTIVATION OF ACTIVATOR
PROTEIN-1 (AP-1) AND C-JUN N-TERMINAL KINASE (JNK)
AP-1 is another transcription factor that has been closely linked with proliferation and transforma-
tion of tumor cells [63]. The activation of AP-1 requires the phosphorylation of c-jun through
activation of stress-activated kinase JNK [64]. The activation of JNK is also involved in cellular
transformation [65]. Curcumin has been shown to inhibit the activation of AP-1 induced by tumor
promoters [66] and JNK activation induced by carcinogens [67].
Dickinson et al. [68] have demonstrated that the beneficial effects elicited by curcumin appear
to be due to changes in the pool of transcription factors that compose EpRE and AP-1 complexes,
affecting gene expression of glutamate-cysteine ligase and other phase II enzymes. Squires et al.
[69] have demonstrated that curcumin suppresses the proliferation of tumor cells through inhibition
of Akt/PKB activation.
23.2.8 CURCUMIN SUPPRESSES THE INDUCTION OF ADHESION MOLECULES
The expression of various cell surface adhesion molecules such as intercellular cell adhesion
molecule-1, vascular cell adhesion molecule-1, and endothelial leukocyte adhesion molecule-1 on
endothelial cells is absolutely critical for tumor metastasis [70]. The expression of these molecules
is in part regulated by nuclear factor NF-kB [71]. We have shown that treatment of endothelial
cells with curcumin blocks the cell surface expression of adhesion molecules, and this accompanies
the suppression of tumor-cell adhesion to endothelial cells [72]. We also have demonstrated that
down-regulation of these adhesion molecules is mediated through the down-regulation of NF-kB
activation [72]. Jaiswal et al. [73] showed that curcumin treatment causes p53- and p21-independent
G(2)/M phase arrest and apoptosis in colon cancer cell lines. Their results suggest that curcumin
treatment impairs both Wnt signaling and cell-cell adhesion pathways, resulting in G(2)/M-phase
arrest and apoptosis in HCT-116 cells.
23.2.9 CURCUMIN DOWN-REGULATES CYCLOOXYGENASE-2 (COX-2) EXPRESSION
Overexpression of COX-2 has been shown to be associated with a wide variety of cancers,
including colon [74], lung [75], and breast [76] cancers. The role of COX-2 in suppression of
apoptosis and tumor cell proliferation has been demonstrated [77]. Furthermore, Celebrex, a
specific inhibitor of COX-2, has been shown to suppress mammary carcinogenesis in animals
[78]. Several groups have shown that curcumin down-regulates the expression of COX-2 protein
in different tumor cells [29, 56], most likely through the down-regulation of NF-kB activation
[56], which is needed for COX-2 expression.

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23.2.10 CURCUMIN INHIBITS ANGIOGENESIS
For most solid tumors, including breast cancer, angiogenesis (blood vessel formation) is essential
for tumor growth and metastasis [79]. The precise mechanism that leads to angiogenesis is not
fully understood, but growth factors that cause proliferation of endothelial cells have been shown
to play a critical role in this process. Curcumin has been shown to suppress the proliferation of
human vascular endothelial cells in vitro [80] and abrogate the fibroblast growth-factor-2-induced
angiogenic response in vivo [81], thus suggesting that curcumin is also an antiangiogenic factor.
Indeed curcumin has been shown to suppress angiogenesis in vivo [82].
To elucidate possible mechanisms of antiangiogenic activity by curcumin, Park et al. [83]
performed cDNA microarray analysis and found that curcumin modulated cell-cycle-related gene
expression. Specifically, curcumin induced G0/G1- and G2/M-phase cell-cycle arrest; up-regu-
lated CDKIs, p21WAF1/CIP1, p27KIP1, and p53; and slightly down-regulated cyclin B1 and
cdc2 in ECV304 cells. The up-regulation of CDKIs by curcumin played a critical role in the
regulation of cell-cycle distribution in these cells, which may underlie the antiangiogenic activity
of curcumin.
23.2.11 CURCUMIN SUPPRESSES THE EXPRESSION OF MMP9 AND INDUCIBLE
NITRIC OXIDE SYNTHASE (INOS)
The MMPs make up a family of proteases that play a critical role in tumor metastasis [84]. One
of them, MMP9, has been shown to be regulated by NF-kB activation, and curcumin has been
shown to suppress its expression [85]. Curcumin has also been demonstrated to down-regulate
iNOS expression, also regulated by NF-kB and involved in tumor metastasis [86]. These observa-
tions suggest that curcumin must have antimetastatic activity. Indeed, there is a report suggesting
that curcumin inhibits tumor metastasis [87].
23.2.12 CURCUMIN DOWN-REGULATES CYCLIN D1 EXPRESSION
Cyclin D1, a component subunit of cyclin-dependent kinase Cdk4 and Cdk6, is a rate-limiting
factor in progression of cells through the first gap (G1) phase of the cell cycle [88]. Cyclin D1
has been shown to be overexpressed in many cancers including breast, esophagus, head and neck,
and prostate [89–94]. It is possible that the antiproliferative effects of curcumin are due to
inhibition of cyclin D1 expression. We found that curcumin can indeed down-regulate cyclin D1
expression [35, 43, 95], and this down-regulation occurred at the transcriptional and posttran-
scriptional level.
23.2.13 CURCUMIN IS CHEMOPREVENTIVE
Several studies suggest that curcumin has chemopreventive potential. Huang et al. [96] found
that topical application of curcumin inhibits tumor initiation by benzo[a]pyrine (BaP) and tumor
promotion by TPA in mouse skin. Dietary curcumin (commercial grade) inhibits BaP-induced
forestomach carcinogenesis, N-ethyl-N¢-nitro-N-nitrosoguanidine (ENNG)-induced duodenal
carcinogenesis, and azoxymethane (AOM)-induced colon carcinogenesis. Dietary curcumin had
little or no effect on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung car-
cinogenesis and 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast carcinogenesis in
mice. Poor circulating bioavailability of curcumin may account for the lack of lung and breast
carcinogenesis inhibition.
Perkins et al. [97] showed that curcumin prevents the development of adenomas in the intestinal
tract of the C57Bl/6J Min/+ mouse, a model of human familial adenomatous polyposis coli (APC).
To aid in the rational development of curcumin as a colorectal cancer-preventive agent, the group
explored the link between its chemopreventive potency in the Min/+ mouse and levels of drug and

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Curcumin Derived from Turmeric (Curcuma longa): a Spice for All Seasons
357
metabolites in target tissue and plasma. Mice received dietary curcumin for 15 weeks, after which
adenomas were enumerated. Levels of curcumin and metabolites were determined by high-performance
liquid chromatography (HPLC) in plasma, tissues, and feces of mice after either long-term ingestion
of dietary curcumin or a single dose of [14C] curcumin (100 mg/kg) via the intraperitoneal (i.p.)
route. Whereas curcumin at 0.1% in the diet was without effect, at 0.2 and 0.5%, it reduced adenoma
multiplicity by 39 and 40%, respectively, compared with untreated mice. Hematocrit values in
untreated Min/+ mice were drastically reduced compared with those in wild-type C57Bl/6J mice.
Dietary curcumin partially restored the suppressed hematocrit. Traces of curcumin were detected
in the plasma. Its concentration in the mucosa of the small intestine, between 39 and 240 nmol/g
of tissue, reflected differences in dietary concentration. [14C] curcumin disappeared rapidly from
tissues and plasma within 2 to 8 h after dosing. Curcumin may be useful in the chemoprevention
of human intestinal malignancies related to Apc mutations. The comparison of dose, resulting
curcumin levels in the intestinal tract, and chemopreventive potency suggested tentatively that a
daily dose of 1.6 g of curcumin is required for efficacy in humans. A clear advantage of curcumin
over nonsteroidal anti-inflammatory drugs is its ability to decrease intestinal bleeding linked to
adenoma maturation.
Helicobacter pylori is a Group 1 carcinogen and is associated with the development of gastric
and colon cancer. Mahady et al. [98] have demonstrated that curcumin inhibits the growth of H.
pylori cagA+ mouse strains in vitro, and this may be one of the mechanisms by which curcumin
exerts its chemopreventive effects.
In another study, Perkins and coworkers [97] found that the nonsteroidal anti-inflammatory
drug aspirin and curcumin retard adenoma formation when administered long-term to Apc(Min/+)
mice, a model of human familial APC. Aspirin administered to Apc (Min/+) mice postweaning was
not effective, though curcumin given postweaning was active. Here the hypothesis was tested that
dietary aspirin (0.05%) or curcumin (0.2%) prevents or delays adenoma formation in offspring
when administered to Apc (Min/+) mothers and up to the end of weaning. Whereas curcumin was
without effect when administered afterward, aspirin reduced the numbers of intestinal adenomas
by 21%. When aspirin given up to the end of weaning was combined with curcumin administered
from the end of weaning for the rest of the animals’ lifetime, intestinal adenoma numbers were
reduced by 38%. The combination was not superior to intervention postweaning with curcumin
alone. These results show that aspirin exerts chemopreventive activity in the Apc(Min/+) mouse
during tumor initiation/early promotion, while curcumin is efficacious when given at a later stage
of carcinogenic progression. Thus, the results suggest that in this mouse model, aspirin and curcumin
act during different “windows” of neoplastic development.
Recently, Van der Logt et al. [99] demonstrated that curcumin exerted its anticarcinogenic
effects in gastrointestinal cancers through the induction of UDP-glucuronosyltransferase enzymes.
23.2.14 CURCUMIN INHIBITS TUMOR GROWTH AND METASTASIS IN ANIMALS
Kuttan et al. [100] examined the anticancer potential of curcumin in vitro using tissue culture
methods and in vivo in mice using Dalton’s lymphoma cells grown as ascites. Initial experiments
indicated that curcumin reduced the development of animal tumors. They encapsulated curcumin
(5 mg/ml) into neutral and unilamellar liposomes prepared by sonication of phosphatidylcholine
and cholesterol. An aliquot of liposomes (50 mg/kg) was given i.p. to mice the day after giving
the Dalton’s lymphoma cells and continued for 10 days. After 30 days and 60 days, surviving
animals were counted. When curcumin was used in liposomal formulations at concentration of
1 mg/animal, all animals survived 30 days, and only two of the animals developed tumors and died
before 60 days.
Busquets [101] showed that systemic administration of curcumin (20 mg/kg body weight) for
6 consecutive days to rats bearing the highly cachectic Yoshida AH-130 ascites hepatoma resulted
in an important inhibition of tumor growth (31% of total cell number). Interestingly, curcumin was

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also able to reduce by 24% in vitro tumor cell content at concentrations as low as 0.5 mM without
promoting any apoptotic events. Although systemic administration of curcumin has previously been
shown to facilitate muscle regeneration, administration of the compound to tumor-bearing rats did
not result in any changes in muscle wasting, when compared with the untreated tumor-bearing
animals. Indeed, both the weight and protein content of the gastrocnemius muscle significantly
decreased as a result of tumor growth, and curcumin was unable to reverse this tendency. It was
concluded that curcumin, in spite of having clear antitumoral effects, has little potential as an
anticachectic drug in the tumor model used in the study.
Menon et al. [102] reported curcumin-induced inhibition of B16F-10 melanoma lung
metastasis in mice. Oral administration of curcumin at concentrations of 200 nmol/kg body
weight reduced the number of lung tumor nodules by 80%. The life span of the animals treated
with curcumin was increased by 143.85% [102]. Moreover, lung collagen hydroxyproline and
serum sialic acid levels were significantly lower in treated animals than in the untreated controls.
Curcumin treatment (10 mg/ml) significantly inhibited the invasion of B16F-10 melanoma cells
across the collagen matrix of a Boyden chamber. Gelatin zymographic analysis of the trypsin-
activated B16F-10 melanoma cells’ sonicate revealed no metalloproteinase activity. Curcumin
treatment did not inhibit the motility of B16F-10 melanoma cells across a polycarbonate filter
in vitro. These findings suggest that curcumin inhibits the invasion of B16F-10 melanoma cells
by inhibition of MMPs, thereby inhibiting lung metastasis.
Curcumin decreases the proliferative potential and increases apoptotic potential of both
androgen-dependent and androgen-independent prostate cancer cells in vitro, largely by modulat-
ing the apoptosis-suppressor proteins and by interfering with the growth factor receptor signaling
pathways as exemplified by the EGF receptor. To extend these observations, Dorai et al. [103]
investigated the anticancer potential of curcumin in a nude mouse prostate cancer model. The
androgen-dependent LNCaP prostate cancer cells were grown, mixed with Matrigel, and injected
subcutaneously. The experimental group received a synthetic diet containing 2% curcumin for up
to 6 weeks. At the end point, mice were killed, and sections taken from the excised tumors were
evaluated for pathology, cell proliferation, apoptosis, and vascularity. Results showed that cur-
cumin induced a marked decrease in the extent of cell proliferation, as measured by the BrdUrd
(bromodeoxyuridine) incorporation assay, and a significant increase in the extent of apoptosis, as
measured by an in situ cell death assay. Moreover, a significant decrease in the microvessel density,
as measured by CD31 antigen staining, was also seen. It was concluded that curcumin was a
potentially therapeutic anticancer agent, as it significantly inhibited prostate cancer growth, as
exemplified by LNCaP in vivo, and it had the potential to prevent the progression of this cancer
to its hormone refractory state.
23.2.15 CURCUMIN INHIBITS ANDROGEN RECEPTORS AND AR-RELATED COFACTORS
Nakamura et al. [104] have evaluated the effects of curcumin in cell growth, activation of signal
transduction, and transforming activities of both androgen-dependent and -independent cell lines.
The prostate cancer cell lines LNCaP and PC-3 were treated with curcumin, and its effects on
signal transduction and expression of androgen receptor (AR) and AR-related cofactors were
analyzed. Their results showed that curcumin down-regulates transactivation and expression of
AR, AP-1, NF-kB, and CREB (cAMP response element-binding protein)-binding protein (CBP).
It also inhibited the transforming activities of both cell lines, as evidenced by reduced colony
forming ability in soft agar. These studies suggest that curcumin has a potential therapeutic effect
on prostate cancer cells through down-regulation of AR and AR-related cofactors, AP-1, NF-kB,
and CBP.
Overall, numerous mechanisms as indicated above could account for the tumor-suppressive
effects of curcumin (Figure 23.3). Curcumin also has modulatory effects in diseases besides cancer
(Figure 23.4). These effects are described in Section 23.3 and Section 23.4.

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