Models for prevention and treatment of cancer: Problems vs promises

Current estimates from the American Cancer Society and from the International Union Against Cancer indicate that 12 million cases of cancer were diagnosed last year, with 7 million deaths worldwide; these numbers are expected to double by 2030 (27 million cases with 17 million deaths). Despite tremendous technological developments in all areas, and President Richard Nixon’s initiative in the 1974 “War against Cancer”, the US cancer incidence is the highest in the world and the cancer death rate has not significantly changed in the last 50 years (193.9 per 100,000 in 1950 vs 193.4 per 100,000 in 2002). Extensive research during the same time, however, has revealed that cancer is a preventable disease that requires major changes in life style; with one third of all cancers assigned to Tobacco, one third to diet, and remaining one third to the environment. Approximately 20 billion dollars are spent annually to find a cure for cancer. We propose that our inability to find a cure to cancer lies in the models used. Whether cell culture or animal studies, no model has yet been found that can reproduce the pathogenesis of the disease in the laboratory. Mono-targeted therapies, till know in most cases, have done a little to make a difference in cancer treatment. Similarly, molecular signatures/predictors of the diagnosis of the disease and response are also lacking. This review discusses the pros and cons of current cancer models based on cancer genetics, cell culture, animal models, cancer biomarkers/signature, cancer stem cells, cancer cell signaling, targeted therapies, therapeutic targets, clinical trials, cancer prevention, personalized medicine, and off-label uses to find a cure for cancer and demonstrates an urgent need for “out of the box” approaches.
Today, it is well accepted that dysregulation in cell growth leads to cancer. Although Percival Pott was the first to show in 1775 that carcinogens can cause cancer (he noted the association between coal dust and scrotal cancer in chimney sweeps), the mechanism by which various carcinogens cause cancer is now well known. The “initiation” step involves interaction of carcinogens with DNA that leads to transformation of normal cells to tumor cells. This step is usually followed by the “promotion” step, in which the cancer cells proliferate and form tumors. This step is mediated through various life style factors and may take as many as 20 years to result in full-fledged cancer.

Various steps in the development of cancer in humans. Transformation or initiation of cells by various carcinogens leads to promotion by various agents and this ultimately leads to tumors. During initiation, a carcinogen interacts with the DNA resulting in various somatic mutations.

Aggarwal BB, Danda D, Gupta S & Gehlot P. Models for prevention and treatment of cancer: Problems vs promises. Biochemical Pharmacology. Volume 78, Issue 9, 1 November 2009, Pp. 1083-94. doi:10.1016/j.bcp.2009.05.027

ANDROGRAPHOLIDE

Plant-derived natural products occupy an important position in the area of cancer chemotherapy. Molecules such as vincristine, vinblastine, paclitaxel, camptothecin derivatives, epipodophyllotoxin, and so forth, are invaluable contributions of nature to modern medicine. However, the quest to find out novel therapeutic compounds for cancer treatment and management is a never-ending venture; and diverse plant species are persistently being studied for identification of prospective anticancer agents. In this regard, Andrographis paniculata Nees, a well-known plant of Indian and Chinese traditional system of medicines, has drawn attention of researchers in recent times. Andrographolide, the principal bioactive chemical constituent of the plant has shown credible anticancer potential in various investigations around the globe. In vitro studies demonstrate the capability of the compound of inducing cell-cycle arrest and apoptosis in a variety of cancer cells at different concentrations. Andrographolide also shows potent immunomodulatory and anti-angiogenic activities in tumorous tissues. Synthetic analogues of the compound have also been created and analyzed, which have also shown similar activities. Although it is too early to predict its future in cancer chemotherapy, the prologue strongly recommends further research on this molecule to assess its potential as a prospective anticancer agent.

Andrographolide activates the extrinsic death receptor pathway (including caspase-3 and caspase-8) and induces apoptotic cell death in certain human cancer cell types [1]. In some cell types (type 1), the activation of caspase-8 is sufficient to activate the effector caspases (caspase 3/7), whereas in majority of cell types (type 2), the effector caspase activation requires amplification of signal through mitochondria. This was elucidated through another study on three different human cancer lines (including cervical, breast and hepatoma cell lines) by Zhou et al. [2], in which around 8-fold increase in the caspase 3/7 activity was observed after treatment with andrographolide (50  M for 6 h), against control [2]. The pro-apoptotic Bcl-2 family members (bid and bax) are the key mediators in relaying cell death signaling initiated by andrographolide from caspase-8 to mitochondria and then to downstream effector caspase 3, eventually leading to cytochrome c release and apoptotic cell death [2,3]. A recent work demonstrates that tumor necrosis factor-

(TNF-) related apoptosis inducing ligand (TRAIL—an important member of extrinsic apoptosis pathway) was significantly enhanced in various human cancer cell lines after treatment with andrographolide, [50]. TRAIL is an important anti-cancer agent, as it can preferentially kill cancer cells amongst normal cells and therefore is a very important molecule in cancer research [51]. Some kinds of cancer cells develop resistance towards TRAIL, which is a major constraint in TRAIL mediated apoptosis. Thus, compounds that enhance TRAIL expression or are able to re-sensitize resistant cancer cells to TRAIL induced apoptosis are extremely valuable [52, 53]. In this context andrographolide is a promising molecule as it could enhance TRAIL expression via up-regulation of death receptor (DR-4) and also re-sensitize resistant cancer cells to TRAIL-induce apoptosis [4]. Further studies in this direction might help in developing andrographolide as a sensitizer for TRAIL induced apoptosis in various kinds of tumors.

Studies have demonstrated that andrographolide is also effective in combination therapy. Andrographolide increased the apoptosis rate in multidrug resistant cancer cells, when used in combination treatment along with other anticancer agents like 5-florouracil (5-FU), adriamycin and cisplatin [6]. Andrographolide individually as well as in combination with 5-FU was assessed in treatment of human carcinoma HCC cells, where it could induce synergistic apoptosis [7]. Apart from inducing apoptosis in cancer cells, the compound is also able to induce cell differentiation in proliferating cancer cells. The myeloid leukemia (M1) cells of mouse were directed to differentiate into phagocytes following treatment with andrographolide. This particular activity is rarely found in plant-derived anti-cancer agents and thus is of particular interest [8].

1. T. G. Kim, K. K. Hwi, and C. S. Hung, “Morphological and biochemical changes of andrographolide-induced cell death in human prostatic adenocarcinoma PC-3 cells,” In Vivo, vol. 19, no. 3, pp. 551–558, 2005.
2. J. Zhou, S. Zhang, C. N. Ong, and H.-M. Shen, “Critical role of pro-apoptotic Bcl-2 family members in andrographolide-induced apoptosis in human cancer cells,” Biochemical Pharmacology, vol. 72, no. 2, pp. 132–144, 2006.
3. S. Harjotaruno, A. Widyawaruyantil,  Sismindari, and N. C. Zaini, “Apoptosis inducing effect of andrographolide on TD-47 human breast cancer cell line,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 4, no. 3, pp. 345–351, 2007.
4. J. Zhou, G.-D. Lu, C.-S. Ong, C.-N. Ong, and H.-M. Shen, “Andrographolide sensitizes cancer cells to TRAIL-induced apoptosis via p53-mediated death receptor 4 up-regulation,” Molecular Cancer Therapeutics, vol. 7, no. 7, pp. 2170–2180, 2008.
6. Y. Han, L. M. Bu, X. Ji, C. Y. Liu, and Z. H. Wang, “Modulation of multidrug resistance by andrographolid in a HCT-8/5-FU multidrug-resistant colorectal cancer cell line,” Chinese Journal of Digestive Diseases, vol. 6, no. 2, pp. 82–86, 2005.
7. L. Yang, D. Wu, K. Luo, S. Wu, and P. Wu, “Andrographolide enhances 5-fluorouracil-induced apoptosis via caspase-8-dependent mitochondrial pathway involving p53 participation in hepatocellular carcinoma (SMMC-7721) cells,” Cancer Letters, vol. 276, no. 2, pp. 180–188, 2009.
7. T. Matsuda, M. Kuroyanagi, S. Sugiyama, K. Umehara, A. Ueno, and K. Nishi, “Cell differentiation-inducing diterpenes from Andrographis paniculata Nees,” Chemical and Pharmaceutical Bulletin, vol. 42, no. 6, pp. 1216–1225, 1994.

Effect of andrographolide treatment on cancer cells. Cancer is a multifaceted disease with complex processes and requires a multi-target therapeutic approach to battle it. A similar kind of action is displayed by andrographolide as it modulates various biochemical pathways of cancer cells thereby inhibiting the tumor growth. The compound exerts cytotoxic effect on various cancer cell types in a time and dose dependent manner. Factors required for tumor progression, nourishment and metastasis are down regulated, that is, cyclins A, D, Cdk2, Cdk4, NF-κB, VEGF, E-selectin, VCAM, Akt, TNF, Bcl2, and so forth. On the other hand tumor suppressor elements like p53, caspases, inhibitory proteins p21, p16, p27, and so forth are up regulated as observed in various studies to investigate anti-cancer potential of andrographolide. Up regulation of death receptor 4 to facilitate TRAIL induced apoptosis is of significant interest. The cumulative effect of all these factorial events leads to inhibition of growth in cancer cells.

Genistein Against Radiation Damage : A Study on Swiss Albino Mice

Radiation has harmful effects on biological systems. The radioprotective effects of an acute administration of the isoflavone, Genistein (4′,5,7-trihydroxyflavone) a product of Soya foods is a solid substance and its molecular formula is C15H10O5 and its molecular weight is 270.24 Daltons. It is also classified as a phytoestrogen. Mice were administered with different doses (100, 200, 300 and 400 mg/kg body weight) of Genistein before 8 Gy gamma radiation and the dose of genistein at which maximum survivability is obtained was selected as optimum dose (200 mg/kg).
The 0.5 ml of Genistein (200 mg/kg) was administered intraperitoneally (I.P.) to mice before gamma irradiation. In mice treated with Genistein (200 mg/kg) 24 hr before irradiation a significant increase in 30 day survival has been recorded in contrast to mice treated with Genistein 15 minutes before irradiation. This observation indicates the radioprotective efficacy with longer retention with the
possible minimum toxicity.
Gaur A, Sharma A, Bhatia AL. Genistein Against Radiation Damage : A Study on Swiss Albino Mice. Asian J. Exp. Sci., Vol. 20, No. 2, 2006 Pp. 269-73

Cinnamon extract induces tumor cell death through inhibition of NFkappaB and AP1

Cinnamomum cassia bark is the outer skin of an evergreen tall tree belonging to the family Lauraceae containing several active components such as essential oils (cinnamic aldehyde and cinnamyl aldehyde), tannin, mucus and carbohydrate. They have various biological functions including anti-oxidant, anti-microbial, anti-inflammation, anti-diabetic and anti-tumor activity. Previously, we have reported that anti-cancer effect of cinnamon extracts is associated with modulation of angiogenesis and effector function of CD8+ T cells. In this study, we further identified that anti-tumor effect of cinnamon extracts is also link with enhanced pro-apoptotic activity by inhibiting the activities NFkappaB and AP1 in mouse melanoma model.
Methods
Water soluble cinnamon extract was obtained and quality of cinnamon extract was evaluated by HPLC (High Performance Liquid Chromatography) analysis. In this study, we tested anti-tumor activity and elucidated action mechanism of cinnamon extract using various types of tumor cell lines including lymphoma, melanoma, cervix cancer and colorectal cancer in vitro and in vivo mouse melanoma model.
Results
Cinnamon extract strongly inhibited tumor cell proliferation in vitro and induced active cell death of tumor cells by up-regulating pro-apoptotic molecules while inhibiting NFkappaB and AP1 activity and their target genes such as Bcl-2, BcL-xL and survivin. Oral administration of cinnamon extract in melanoma transplantation model significantly inhibited tumor growth with the same mechanism of action observed in vitro.
Conclusion
Our study suggests that anti-tumor effect of cinnamon extracts is directly linked with enhanced pro-apoptotic activity and inhibition of NFkappaB and AP1 activities and their target genes in vitro and in vivo mouse melanoma model. Hence, further elucidation of active components of cinnamon extract could lead to development of potent anti-tumor agent or complementary and alternative medicine for the treatment of diverse cancer.
Kwon HK, Hwang JS, So JS, Lee CG, Sahoo A, Ryu JH, Jeon WK, Ko BS, Im CR, Lee SH, Park ZY, Im SH. Cinnamon extract induces tumor cell death through inhibition of NFkappaB and AP1, BMC Cancer. 2010 Jul 24;10:392.

Genistein inhibits radiation-induced activation of NF-κB in prostate cancer cells promoting apoptosis and G2/M cell cycle arrest

New cancer therapeutic strategies must be investigated that enhance prostate cancer treatment while minimizing associated toxicities. We have previously shown that genistein, the major isoflavone found in soy, enhanced prostate cancer radiotherapy in vitro and in vivo. In this study, we investigated the cellular and molecular interaction between genistein and radiation using PC-3 human prostate cancer cells.
Methods
Tumor cell survival and progression was determined by clonogenic analysis, flow cytometry, EMSA analysis of NF-κB, and western blot analysis of cyclin B1, p21WAF1/Cip1, and cleaved PARP protein.
Results
Genistein combined with radiation caused greater inhibition in PC-3 colony formation compared to genistein or radiation alone. Treatment sequence of genistein followed by radiation and continuous exposure to genistein showed optimal effect. Cell cycle analysis demonstrated a significant dose- and time-dependent G2/M arrest induced by genistein and radiation that correlated with increased p21WAF1/Cip1 and decreased cyclin B1 expression. NF-κB activity was significantly decreased by genistein, yet increased by radiation. Radiation-induced activation of NF-κB activity was strongly inhibited by genistein pre-treatment. A significant and striking increase in cleaved PARP protein was measured following combined genistein and radiation treatment, indicating increased apoptosis.
Conclusion
A mechanism of increased cell death by genistein and radiation is proposed to occur via inhibition of NF-κB, leading to altered expression of regulatory cell cycle proteins such as cyclin B and/or p21WAF1/Cip1, thus promoting G2/M arrest and increased radiosensitivity. These findings support the important and novel strategy of combining genistein with radiation for the treatment of prostate cancer.
Raffoul JJ, Wang Y, Omer Kucuk O, et al. Genistein inhibits radiation-induced activation of NF-κB in prostate cancer cells promoting apoptosis and G2/M cell cycle arrest. BMC Cancer 2006, 6:107. doi:10.1186/1471-2407-6-107

Genistein Potentiates the Radiation Effect on Prostate Carcinoma Cells

We have shown previously that genistein, the major isoflavone in soybean, inhibited the growth of human prostate cancer cells in vitro by affecting the cell cycle and inducing apoptosis. To augment the effect of radiation for prostate carcinoma, we have now tested the combination of genistein with photon and neutron radiation on prostate carcinoma cells in vitro. The effects of photon or neutron radiation alone or genistein alone or both combined were evaluated on DNA synthesis, cell growth, and cell ability to form colonies. We found that neutrons were more effective than photons for the killing of prostate carcinoma cells in vitro, resulting in a relative biological effectiveness of 2.6 when compared with photons. Genistein at 15 μm caused a significant inhibition in DNA synthesis, cell growth, and colony formation in the range of 40–60% and potentiated the effect of low doses of 200–300 cGy photon or 100–150 cGy neutron radiation. The effect of the combined treatment was more pronounced than with genistein or radiation alone. Our data indicate that genistein combined with radiation inhibits DNA synthesis, resulting in inhibition of cell division and growth. Genistein can augment the effect of neutrons at doses ∼2-fold lower than photon doses required to observe the same efficacy. These studies suggest a potential of combining genistein with radiation for the treatment of localized prostate carcinoma.
Hillman GG, Forman JD, Kucuk O, Yudelev M, et al. Genistein Potentiates the Radiation Effect on Prostate Carcinoma Cells. Clin Cancer Res February 2001 7; 382