Lifestyle and medical approaches to cancer prevention

A recent development of new therapeutic agents and novel drug targets for cancer treatment

Despite recent advances in cancer diagnosis, prevention, detection, as well as management, the disease is expected to be the top cause of death globally. The chemotherapy approach for cancer has become more advanced in its design, yet no medication can cure enough against all types of cancer and its stage. Thus, this review aimed to summarize a recent development of new therapeutic agents and novel drug targets for the treatment of cancer. Several obstacles stand in the way of effective cancer treatment and drug development, including inaccessibility of tumor site by appropriate drug concentration, debilitating untoward effects caused by non-selective tissue distribution of chemotherapeutic agents, and occurrence of drug resistance, which leads to cross-resistance to a variety of drugs. Resistance to treatment with anticancer drugs results from multiple factors and the most common reason for acquiring drug resistance is marking and expelling drugs that prevent cancer cells to be targeted by chemotherapeutic agents. Moreover, insensitivity to drug-induced apoptosis, alteration, and mutation of drug target and interference/change of DNA replication are other main causes of treatment failure.

Phenolic content, antioxidant, cytotoxic and antiproliferative effects of fractions of Vigna subterraenea (L.) verdc from Mpumalanga, South Africa

Consistent intake of legumes has been correlated with decreased possibility of developing colorectal cancer (CRC) due to the content of some phytochemicals like polyphenols. Bambara groundnut (BGN) is an underutilized crop with a rich nutritional profile, but have not been exploited for its nutraceutical and medicinal benefits. In this study, total polyphenol, flavonoid (flavonol and flavanol) content, antioxidant activity and cytotoxicity/antiproliferative properties of 70% ethanolic extracts of whole BGN, cotyledon and seed coat on Caco-2 and HT-29 colon cancer cells were evaluated. Seed coat had a significantly (p < 0.05) higher composition of total polyphenol, flavonol and flavan-3-ol (flavanol) compared to whole seed and cotyledon. Antioxidant activity determined with ferric reducing antioxidant power (FRAP), 2,2- azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC) assays, showed that seed coat with higher polyphenolic content had significantly (p < 0.05) greater antioxidant activity. BGN fractions demonstrated cytotoxic and antiproliferative effects against HT-29 and Caco-2 colon cancer cells in a dose-dependent manner, with seed coat and whole seed exhibiting greater cytotoxicity and higher antiproliferative activity and colon cancer cell inhibition. Extracts of the cotyledon also showed cytotoxic activity and hindered cancer cell growth/division but to a significantly (p < 0.05) lower magnitude. BGN parts indicated a greater cytotoxic effect and potential to slow down Caco-2 colon cancer cell growth and division over HT-29. This result provides new knowledge on the possible health benefits of BGN, as well as the potential for product development and may influence its consumption and utilisation.

Dietary patterns and food groups are linked to the risk of urinary tract tumors in Argentina

Epidemiological and laboratory research has shown that dietary components are associated with the risk of developing urinary tract tumors (UTT). The purpose of this case-control study, carried out between 2004 and 2008 in Córdoba, a Mediterranean city in Argentina, was to describe the role of dietary patterns and to investigate any association with the risk of developing UTT. One hundred and sixty-eight patients with histologically confirmed transitional UTT and 334 controls with acute, nonneoplastic, and nonurinary tract diseases from the same hospitals were studied. All patients were interviewed about their food habits and their exposure to a number of known or suspected risk factors for UTT. Multiple correspondence analysis was used to explore dietary patterns and data analyses were carried out by calculating odds ratios and their 95% confidence intervals by using multiple logistic regression. Two main dietary patterns identified were a 'prudent' pattern that was linked to controls and a 'western' pattern that was associated with cases. A frequent intake of vegetable oils, lean meats, grains, and fruits, the moderate use of alcohol (mainly red wine) together with potato and sweet consumption, and the habit of taking at least four meals per day, were associated with a reduced risk for UTT. In contrast, frequent consumption of infusions (mainly maté), potatoes, alcohol, sweets, and processed meat resulted in a high risk for UTT. The dietary patterns of our population have a role in the development of UTT, thus implying that appropriate nutritional education may decrease this risk.

Pomegranate extract induces apoptosis in human prostate cancer cells by modulation of the IGF-IGFBP axis

The IGF axis is critical for the regulation of apoptosis in many human cancer cell lines. Recently, potent anti-tumorigenic effects of pomegranate juice and extracts have been reported. Consequently, pomegranate has potential not only as a treatment but also as a preventative measure against certain types of cancer, including prostate. In this study, we investigated the relationship between pomegranate-induced apoptosis in human prostate cancer cells and the IGF/IGFBP system. Treatment of LAPC4 prostate cancer cells with 10microg/ml POMx, a highly potent pomegranate extract prepared from skin and arils minus seeds and standardized to ellagitannin content (37% punicalagins by HPLC), resulted in inhibition of cell proliferation and induction of apoptosis. Interestingly, co-treatment with POMx and IGFBP-3 revealed synergistic stimulation of apoptosis and additive inhibition of cell growth. Western blot analysis revealed that treatment with POMx or POMx/IGFBP-3 combination resulted in increased JNK phosphorylation, and decreased Akt and mTOR activation, consistent with a growth inhibitory, pro-apoptotic function. We also investigated the relationship between IGF-1 and pomegranate-induced apoptosis in 22RV1 prostate cancer cells. Co-treatment with 100ng/ml IGF-1 completely blocked apoptosis induction by POMx. In contrast, IGF-I failed to inhibit POMx-induced apoptosis in R(-) cells, suggesting the importance of IGF-IR. POMx-treatment decreased Igf1 mRNA expression in a dose-dependent manner indicating that its actions also involve tumor-specific suppression of IGF-1. These studies revealed novel interactions between the IGF system and pomegranate-induced apoptosis.

Incidence, risk factors, and pathogenesis of second malignancies in patients with non-Hodgkin lymphoma

Most Non-Hodgkin's Lymphoma patients will survive their diagnosis. High dose chemotherapy and autologous stem cell transplantation, and radiation therapy have all been implicated as risk factors to secondary cancer development. Herein, we will review the molecular biology, examine the epidemiologic findings, discuss the impact of both chemotherapy and radiotherapy, and focus on the special populations of pediatrics and high dose chemotherapy and autologous stem cell transplantation with regard to secondary cancer development.

Tea polyphenols inhibit cyclooxygenase-2 expression and block activation of nuclear factor-kappa B and Akt in diethylnitrosoamine induced lung tumors in Swiss mice

BACKGROUND

Due to lack of validated screening methods and hence poor prognosis, treatment of lung cancer has not still improved up to the expectations. Therefore, risk of lung cancer needs to be minimized by efficient preventive measures. Tea (Camellia sinensis) and its bioactive polyphenols have been associated with prevention of human cancer for several organs. Thus, intake of tea polyphenols seems to be a viable mean to control lung cancer burden. In the present study, we studied the chemopreventive effects of green tea polyphenols (GTP) and black tea polyphenols (BTP) against diethylnitrosoamine (DEN) induced lung tumors in Swiss albino mice.

RESULTS

Chemopreventive potential of tea polyphenols, was recorded as evident by, low incidence of alveologenic tumors in lungs of animals at tested doses (0.1% and 0.2% of both GTP and BTP) when compared with DEN (20 mg/kg b wt) treated animals. As a mechanism of cancer chemoprevention cellular signaling pathways were also targeted. GTP and BTP treatment inhibited the expression of Akt, cyclooxygenase-2 and inactivated nuclear factor-kappa B via blocking phosphorylation and subsequent degradation of IkappaB alpha.

CONCLUSION

Thus, the study suggests that polyphenolic constituents of both cultivars of tea, i.e. green and black, have chemopreventive effects in DEN induced lung tumorigenesis in Swiss albino mice.

Difluoromethylornithine plus sulindac for the prevention of sporadic colorectal adenomas: a randomized placebo-controlled, double-blind trial

Preclinical studies of chemoprevention drugs given in combination at low doses show remarkable efficacy in preventing adenomas with little additional toxicities, suggesting a strategy to improve risk to benefit ratios for preventing recurrent adenomas. Three hundred seventy-five patients with history of resected (> or =3 mm) adenomas were randomly assigned to receive oral difluoromethylornithine (DFMO) 500 mg and sulindac 150 mg once daily or matched placebos for 36 months, stratified by use of low-dose aspirin (81 mg) at baseline and clinical site. Follow-up colonoscopy was done 3 years after randomization or off-study. Colorectal adenoma recurrence was compared among the groups with log-binomial regression. Comparing the outcome in patients receiving placebos to those receiving active intervention, (a) the recurrence of one or more adenomas was 41.1% and 12.3% (risk ratio, 0.30; 95% confidence interval, 0.18-0.49; P < 0.001); (b) 8.5% had one or more advanced adenomas, compared with 0.7% of patients (risk ratio, 0.085; 95% confidence interval, 0.011-0.65; P < 0.001); and (c) 17 (13.2%) patients had multiple adenomas (>1) at the final colonoscopy, compared with 1 (0.7%; risk ratio, 0.055; 0.0074-0.41; P < 0.001). Serious adverse events (grade > or =3) occurred in 8.2% of patients in the placebo group, compared with 11% in the active intervention group (P = 0.35). There was no significant difference in the proportion of patients reporting hearing changes from baseline. Recurrent adenomatous polyps can be markedly reduced by a combination of low oral doses of DFMO and sulindac and with few side effects.

Citrus compounds inhibit inflammation- and obesity-related colon carcinogenesis in mice

Dietary polyphenols are important potential chemopreventive natural agents. Other agents, such as citrus compounds, are also candidates for cancer chemopreventives. They act on multiple key elements in signal transduction pathways related to cellular proliferation, differentiation, apoptosis, inflammation, and obesity. This short review article provides our findings of preclinical studies on potential chemopreventive activities of dietary citrus compounds, auraptene, collinin, and citrus unshiu segment membrane (CUSM), using clitis- and obesity-related colon tumorigenesis models. Dietary feeding with auraptene and collinin at dose levels of 0.01% and 0.05% significantly lowered the incidence (50-60% reduction) and multiplicity (67-80% reduction) of colonic adenocarcinomas induced by azoxymetahene [AOM, single intraperitoneal injection of 10 mg/kg body weight (bw)] and dextran sodium sulfate (1% in drinking water). Anti-inflammatory potency of aurapene and collinin may contribute to the effects. Administration with CUSM at 3 doses in diet significantly inhibited development of aberrant crypts foci induced by 5 weekly subcutaneous injections of AOM (15 mg/kg bw) in male db/db mice: 53% inhibition by 0.02% CUSM, 54% inhibition by 0.1% CUSM, and 59% inhibition by 0.5% CUSM. CUSM treatment also decreased serum level of triglycerides. Our findings suggest that certain citrus materials are capable of inhibiting clitis- and obesity-related colon carcinogenesis.

Parasitic loranthus from Loranthaceae rather than Viscaceae potently inhibits fatty acid synthase and reduces body weight in mice

AIM OF THE STUDY

Our previous results have shown one species of parasitic loranthus (Taxillus chinensis (DC.) Dancer) exhibits potent inhibition on fatty acid synthase (FAS) that is proposed to be a potential therapeutic target for treatment of obesity. However, the medicinal parasitic loranthus come from tens of plants of two families, the Loranthaceae and the Viscaceae. This study was carried out to figure out whether these parasitic loranthus from the two families have similar inhibitory ability on FAS, and whether the parasitic loranthus with potent inhibitory ability on FAS significantly reduce body weight of animal.

MATERIALS AND METHODS

CD-1 mice were used to test the effects of samples on their body weight and food intake in 20 days. The reversible and irreversible inhibition on FAS was assayed to study the inhibitory ability of sixteen different medicinal plants from these two families, which were collected in nature.

RESULTS

The reversible inhibitory ability of the extracts from the Loranthaceae was nearly 400-fold stronger than that from the Viscaceae. The species from the genus Taxillus Tieghem showed the best effect on FAS in both reversible and irreversible inhibition. Moreover, the difference in host plants did not affect markedly on the inhibitory ability of parasitic loranthus. The medicinal herb with high inhibitory ability on FAS significantly reduced the body weight and food intake of mice by oral administration.

CONCLUSIONS

The medicinal herbs from the family Loranthaceae, rather than those from the family Viscaceae, should be suitable to apply as botanical sources of parasitic loranthus for weight control. The herbs from genus Taxillus Tieghem are the best.

Cancer is a preventable disease that requires major lifestyle changes

This year, more than 1 million Americans and more than 10 million people worldwide are expected to be diagnosed with cancer, a disease commonly believed to be preventable. Only 5–10% of all cancer cases can be attributed to genetic defects, whereas the remaining 90–95% have their roots in the environment and lifestyle. The lifestyle factors include cigarette smoking, diet (fried foods, red meat), alcohol, sun exposure, environmental pollutants, infections, stress, obesity, and physical inactivity. The evidence indicates that of all cancer-related deaths, almost 25–30% are due to tobacco, as many as 30–35% are linked to diet, about 15–20% are due to infections, and the remaining percentage are due to other factors like radiation, stress, physical activity, environmental pollutants etc. Therefore, cancer prevention requires smoking cessation, increased ingestion of fruits and vegetables, moderate use of alcohol, caloric restriction, exercise, avoidance of direct exposure to sunlight, minimal meat consumption, use of whole grains, use of vaccinations, and regular check-ups. In this review, we present evidence that inflammation is the link between the agents/factors that cause cancer and the agents that prevent it. In addition, we provide evidence that cancer is a preventable disease that requires major lifestyle changes.

Diet supplemented with citrus unshiu segment membrane suppresses chemically induced colonic preneoplastic lesions and fatty liver in male db/db mice

The modulatory effects of dietary citrus unshiu segment membrane (CUSM) on the occurrence of aberrant crypt foci (ACF) and beta-catenin accumulated crypts (BCACs) were determined in male C57BL/KsJ-db/db (db/db) mice initiated with azoxymethane (AOM). Male db/db, db/+ and +/+ mice were given 5 weekly subcutaneous injections of AOM (15 mg/kg body weight), and then they were fed the diet containing 0.02%, 0.1% or 0.5% CUSM for 7 weeks. At Week 12, a significant increase in the numbers of ACF and BCAC was noted in the db/db mice in comparison with the db/+ and +/+ mice. Feeding with CUSM caused reduction in the frequency of ACF in all genotypes of mice and the potency was high in order of the db/db mice, db/+ mice and +/+ mice. The number of BCACs was also reduced by feeding with CUSM, thus resulting in a 28-61% reduction in the db/db mice, possibly due to suppression of cell proliferation activity in the lesions by feeding with CUSM-containing diet. Clinical chemistry revealed a low serum level of triglyceride in mice fed CUSM. In addition, CUSM feeding inhibited fatty metamorphosis and fibrosis in the liver of db/db mice. Our findings show that CUSM in the diet has a chemopreventive ability against the early phase of AOM-induced colon carcinogenesis in the db/db as well as db/+ and +/+ mice, indicating potential use of CUSM in cancer chemoprevention in obese people.

Magnolol-induced apoptosis is mediated via the intrinsic pathway with release of AIF from mitochondria in U937 cells

Magnolol has been reported to have an inhibitory effect on tumor invasion in vitro and in vivo. In this study, we found that treatment with 30 microM magnolol exhibited growth inhibition partly by inducing apoptosis in cultured human leukemia U937 cells and that the apoptosis was induced via the sequential ordering of molecular events; 1) a transient decrease of phosphorylated extracelluar signal-requlated kinase (ERK), 2) translocation of apoptosis inducing factor (AIF) from mitochondria to cytosol concurrent with a decreased membrane potential, and 3) downregulation of bcl-2 protein. Pretreatment of the cells with a pan-caspase inhibitor Z-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK) did not prevent the apoptosis induced by magnolol. These findings indicated that the above-mentioned sequence of intracellular signaling events led to apoptosis in magnolol-treated U937 cells, which was caspase-independent.

The risk of secondary malignancies over 30 years after the treatment of non-Hodgkin lymphoma

BACKGROUND

Survivors of non-Hodgkin lymphoma (NHL) are at increased risk for developing secondary malignancies. For the current study, the authors quantitated this risk in a group of NHL survivors over 30 years of follow-up.

METHODS

Standardized incidence ratios (observed-to-expected [O/E] ratio) and absolute excess risk of secondary malignancies were assessed in 77,876 patients who were diagnosed with NHL between 1973 and 2001 from centers that participated in the National Cancer Institute's Surveillance, Epidemiology, and End Results Program.

RESULTS

There were 5638 patients who developed secondary malignancies, significantly more than the endemic rate (O/E, 1.14; P < .001). Overall, irradiated patients had a similar risk of secondary malignancies compared with unirradiated patients (relative risk, 1.04; 95% confidence interval, 0.98-1.10; P = .21). Irradiated patients had excess risk for sarcomas, breast cancers, and mesothelioma compared with unirradiated survivors (P < .05). Patients age <25 years at the time of their NHL diagnosis had the highest relative increased risk (no radiation: O/E, 2.1; P < .05; radiation: O/E, 4.51; P < .05). Overall, no statistical difference was observed for secondary cancer incidence between females and males (O/E, 1.12 vs. 1.15, respectively). Female survivors of NHL were less likely to develop breast cancer than the general population (O/E, 0.85; P < .05), but women age <25 years at the time of their NHL diagnosis were more likely to develop breast cancer (no radiation: O/E, 2.1; P < .05; radiation: O/E, 4.51; P < .05).

CONCLUSIONS

The overall risk of secondary malignancies was increased for NHL survivors and varied according to age at NHL diagnosis, gender, and treatment.

Pomegranate fruit juice for chemoprevention and chemotherapy of prostate cancer

Prostate cancer is the most common invasive malignancy and the second leading cause of cancer-related deaths among U.S. males, with a similar trend in many Western countries. One approach to control this malignancy is its prevention through the use of agents present in diet consumed by humans. Pomegranate from the tree Punica granatum possesses strong antioxidant and antiinflammatory properties. We recently showed that pomegranate fruit extract (PFE) possesses remarkable antitumor-promoting effects in mouse skin. In this study, employing human prostate cancer cells, we evaluated the antiproliferative and proapoptotic properties of PFE. PFE (10-100 microg/ml; 48 h) treatment of highly aggressive human prostate cancer PC3 cells resulted in a dose-dependent inhibition of cell growth/cell viability and induction of apoptosis. Immunoblot analysis revealed that PFE treatment of PC3 cells resulted in (i) induction of Bax and Bak (proapoptotic); (ii) down-regulation of Bcl-X(L) and Bcl-2 (antiapoptotic); (iii) induction of WAF1/p21 and KIP1/p27; (iv) a decrease in cyclins D1, D2, and E; and (v) a decrease in cyclin-dependent kinase (cdk) 2, cdk4, and cdk6 expression. These data establish the involvement of the cyclin kinase inhibitor-cyclin-cdk network during the antiproliferative effects of PFE. Oral administration of PFE (0.1% and 0.2%, wt/vol) to athymic nude mice implanted with androgen-sensitive CWR22Rnu1 cells resulted in a significant inhibition in tumor growth concomitant with a significant decrease in serum prostate-specific antigen levels. We suggest that pomegranate juice may have cancer-chemopreventive as well as cancer-chemotherapeutic effects against prostate cancer in humans.

Current directions for COX-2 inhibition in breast cancer

Chemotherapy is effective against breast cancer. COX-2 has been implicated in the progression and angiogenesis of cancers. Celecoxib, a cyclooxygenase type 2 (COX-2) inhibitor, has both apoptotic and antiangiogenic activities, and may be of use in treatment of breast tumors which overexpress the COX-2 enzyme. Preliminary clinical trials have shown that the combination of chemotherapy with celecoxib has minimal additional toxicity and it may enhance the effects of the chemotherapy. Beside chemotherapy, celecoxib may promulgate the effect of aromatase inhibitor in breast cancer cells. Animal studies have shown that there are fewer and smaller tumors treated by combining exemestane and celecoxib. Larger clinical trials should be initiated to study the potential anti-cancer effects of celecoxib in breast cancer.