Clinical usage of hypolipidemic and antidiabetic drugs in the prevention and treatment of cancer

Longitudinal cohort study highlights cancer-preventive benefits of lipid-lowering drugs

Cancer prevention is a serious global challenge. We aimed to investigate the relationship between lipid-lowering drugs and cancers. We included participants based on the UK Biobank. Lipid-lowering drug use was defined as new users before enrollment and the primary outcome was cancer incidence. The Cox proportional hazards regression model was used to evaluate the association between drug use and outcome. We also performed a meta-analysis. We found that lipid-lowering drugs were associated with decreased risk of 21 types of cancers, including melanoma, skin cancer, and reproductive, hematological, urinary, digestive, nervous, and endocrine system cancers (all p < 0.0010). Our meta-analysis documented that lipid-lowering drugs reduced the risk of prostate, liver, and gastric cancers, especially (all p < 0.050). Overall, lipid-lowering drugs had protective associations with cancer incidence, suggesting the possible cancer prevention effects even in the general population.

Identification of Key Hypolipidemic Components and Exploration of the Potential Mechanism of Total Flavonoids from Rosa sterilis Based on Network Pharmacology, Molecular Docking, and Zebrafish Experiment

Hyperlipidemia is a prevalent chronic metabolic disease that severely affects human health. Currently, commonly used clinical therapeutic drugs are prone to drug dependence and toxic side effects. Dietary intervention for treating chronic metabolic diseases has received widespread attention. Rosa sterilis is a characteristic fruit tree in China whose fruits are rich in flavonoids, which have been shown to have a therapeutic effect on hyperlipidemia; however, their exact molecular mechanism of action remains unclear. Therefore, this study aimed to investigate the therapeutic effects of R. sterilis total flavonoid extract (RS) on hyperlipidemia and its possible mechanisms. A hyperlipidemic zebrafish model was established using egg yolk powder and then treated with RS to observe changes in the integral optical density in the tail vessels. Network pharmacology and molecular docking were used to investigate the potential mechanism of action of RS for the treatment of hyperlipidemia. The results showed that RS exhibited favorable hypolipidemic effects on zebrafish in the concentration range of 3.0-30.0 μg/mL in a dose-dependent manner. Topological and molecular docking analyses identified HSP90AA1, PPARA, and MMP9 as key targets for hypolipidemic effects, which were exerted mainly through lipolytic regulation of adipocytes and lipids; pathway analysis revealed enrichment in atherosclerosis, chemical carcinogenic-receptor activation pathways in cancers, and proteoglycans in prostate cancer and other cancers. Mover, chinensinaphthol possessed higher content and better target binding ability, which suggested that chinensinaphthol might be an important component of RS with hypolipidemic active function. These findings provide a direction for further research on RS interventions for the treatment of hyperlipidemia.

Hypolipidemic and Antithrombotic Effect of 6'-O-Caffeoylarbutin from Vaccinium dunalianum Based on Zebrafish Model, Network Pharmacology, and Molecular Docking

Vaccinium dunalianum leaf buds make one of the most commonly used herbal teas of the Yi people in China, which is used to treat articular rheumatism, relax tendons, and stimulates blood circulation in the body. In addition, 6'-O-caffeoylarbutin (CA) is a standardized extract of V. dunalianum, which has been found in dried leaf buds, reaching levels of up to 31.76%. Because of the uncommon phenomenon, it is suggested that CA may have a potential therapeutic role in hyperlipidemia and thrombosis. This study was designed to study the efficacy of CA on treating hyperlipidemia and thrombosis and the possible mechanisms behind these effects. Hyperlipidemia and thrombosis zebrafish models were treated with CA to observe variations of the integrated optical density within the vessels and the intensity of erythrocyte staining within the hearts. The possible mechanisms were explored using network pharmacology and molecular docking. The results demonstrate that CA exhibits an excellent hypolipidemic effect on zebrafish at concentrations ranging from 3.0 to 30.0 μg/mL and shows thrombosis inhibitory activity in zebrafish at a concentration of 30.0 μg/mL, with an inhibition rate of 44%. Moreover, network pharmacological research shows that MMP9, RELA, MMP2, PRKCA, HSP90AA1, and APP are major targets of CA for therapy of hyperlipidemia and thrombosis, and may relate to pathways in cancer, chemical carcinogenesis-receptor activation, estrogen signaling pathway, and the AGE-RAGE signaling pathway in diabetic complications.

Clinical potentials of metformin in cancer therapy

Diabetes is a prevalent metabolic disorder that results in several comorbidities including cancer. Cancer becomes the most severe complication of diabetes patients. Growing evidence proved that impaired glucose homeostasis is an independent risk factor for the occurrence of various types of cancers including liver, pancreatic, gastric (stomach), colorectal, kidney, and breast cancers, and influences cancer prognosis. Diabetes mellitus and cancer have a bidirectional relationship, thus there is a need to look for drugs that can be beneficial in treating both diseases. Therefore, more research is focusing on evaluating the role of antihyperglycemic agents in the treatment of various types of cancers. Metformin, an FDA-approved first-line antihyperglycemic agent can be used as a monotherapy or as an adjuvant to chemotherapeutic agents in the treatment of various types of cancer. However, the exact mechanism of metformin as an anticancer agent is still unknown, the majority of the described putative mechanisms focus on promoting the activity of the AMP-activated protein kinase (AMPK) pathway. This review article thus gives insights into the prognosis of cancer in diabetes patients and aims to explore the possible mechanism of action of metformin in the prevention and treatment of cancer.

Metformin Restores the Drug Sensitivity of MCF-7 Cells Resistant Derivates via the Cooperative Modulation of Growth and Apoptotic-Related Pathways

The phenomenon of the primary or acquired resistance of cancer cells to antitumor drugs is among the key problems of oncology. For breast cancer, the phenomenon of the resistance to hormonal or target therapy may be based on the numerous mechanisms including the loss or mutation of estrogen receptor, alterations of antiapoptotic pathways, overexpression of growth-related signaling proteins, etc. The perspective approaches for overcoming the resistance may be based on the usage of compounds such as inhibitors of the cell energetic metabolism. Among the latter, the antidiabetic drug metformin exerts antitumor activity via the activation of AMPK and the subsequent inhibition of mTOR signaling. The experiments were performed on the ERα-positive MCF-7 breast cancer cells, the MCF-7 sublines resistant to tamoxifen (MCF-7/T) and rapamycin (MCF-7/Rap), and on triple-negative MDA-MB-231 breast cancer cells. We have demonstrated metformin’s ability to enhance the cytostatic activity of the tamoxifen and rapamycin on both parent MCF-7 cells and MCF-7-resistant derivates mediated via the suppression of mTOR signaling and growth-related transcriptional factors. The cooperative effect of metformin and tested drugs was realized in an estrogen-independent manner, and, in the case of tamoxifen, was associated with the activation of apoptotic cell death. Similarly, the stimulation of apoptosis under metformin/tamoxifen co-treatment was shown to occur in the MCF-7 cells after steroid depletion as well as in the ERα-negative MDA-MB-231 cells. We conclude that metformin co-treatment may be used for the increase and partial restoration of the cancer cell sensitivity to hormonal and target drugs. Moreover, the combination of metformin with tamoxifen induces the apoptotic death in the ERα-negative breast cancer cells opening the additional perspectives in the treatment of estrogen-independent breast tumors.

Preventive effect of Oenothera rosea on N-methyl-N-nitrosourea-(NMU) induced gastric cancer in rats

Background

Currently, gastric cancer (GC) is considered a public health problem worldwide. Using medicinal plants for the prevention of chronic diseases such as cancer constitutes new alternatives in traditional medicine. Oenothera rosea (OR) could be an option, but it needs to be evaluated.

Aim

The main objective of this study was to evaluate the protective effect of OR extract on N-methyl-N-nitrosourea (NMU)-induced GC in rats.

Methods

In total, 80 male Holtzman rats were randomized into five groups. Group A received the saline solution (5mL/kg), group B received NMU 500 μg/kg (cancer inductor) by oral administration for 16 weeks, and groups C, D, and E were treated with OR extract (100, 200, and 300 mg/kg, respectively) and NMU in order to evaluate the preventive effect on cancer induced by NMU for 16 weeks. Blood and histological samples of stomachs were collected to determine histopathological, biochemical, and hematological parameters between different experimental groups.

Results

Groups C, D, and E presented less histopathological changes such as anaplastic and hyperplastic cells, compared with group B. Hematological and biochemical parameters were recorded, and superoxide dismutase, malondialdehyde, and nitric oxide levels were statistically less than those of NMU group (P<0.05, P<0.01, and P<0.01).

Conclusion

Considering the histopathological signs and the antioxidant activity in vivo as well as hematological and biochemical parameters of ethanolic extract of OR, we concluded that its administration in rats has a protective effect on GC, which is induced experimentally. This species could be studied in clinical trials for patients with GC in the future.

Protective effect of Chuquiraga spinosa extract on N-methyl-nitrosourea (NMU) induced prostate cancer in rats

BACKGROUND

The main objective was to evaluate the possible protective effect of Chuquiraga spinosa extract on N-methyl nitrosourea (NMU)-induced prostate cancer in rats and DU-145 cell line.

MATERIALS AND METHODS

Prostate carcinogenesis was induced in 30 male Holtzman rats by providing cyproterone acetate, testosterone, and NMU. The tumors were monitored and hematological and biochemical parameters and frequency of micronucleated polychromatic erythrocytes were recorded. The cell line was assessed by a cytotoxicity assay.

RESULTS

Oral administration of C. spinosa extract significantly lowered superoxide dismutase malondialdehyde, NO, C-reactive protein, and prostate-specific antigen levels (all P < 0.01 compared with Inductor Group). There was a significant decrease in the frequency of micronucleated polychromatic erythrocytes (P < 0.05). C. spinosa presented a selectivity index of 17.24 in the cytotoxicity assay.

CONCLUSIONS

Considering its anti-inflammatory, antioxidant, and antigenotoxic effects, and important variations on biochemical and hematological parameters, including prostate-specific antigen of C. spinosa extract, we conclude that it has a protective effect on NMU-induced prostate cancer in rats and cytotoxicity in the DU-145 cell line.

Metformin Alleviates Altered Erythrocyte Redox Status During Aging in Rats

Metformin, a biguanide drug commonly used to treat type 2 diabetes, has been noted to function as a caloric restriction mimetic. Its antidiabetic effect notwithstanding, metformin is currently being considered an antiaging drug candidate, although the molecular mechanisms have not yet been unequivocally established. This study aims to examine whether short-term metformin treatment can provide protective effects against oxidative stress in young and old-age rats. Young (age 4 months) and old (age 24 months) male Wistar rats were treated with metformin (300 mg/kg b.w.) for 4 weeks. At the end of the treatment period, an array of biomarkers of oxidative stress were evaluated, including plasma antioxidant capacity measured in terms of ferric reducing ability of plasma (FRAP), reactive oxygen species (ROS), lipid peroxidation (MDA), reduced glutathione (GSH), total plasma thiol (SH), plasma membrane redox system (PMRS), protein carbonyl (PCO), advanced oxidation protein products (AOPPs), and advanced glycation end products (AGEs) in control and experimental groups. Metformin treatment resulted in an increase in FRAP, GSH, SH, and PMRS activities in both age groups compared to respective controls. On the other hand, treated groups exhibited significant reductions in ROS, MDA, PCO, AOPP, and AGE level. Save for FRAP and protein carbonyl, the effect of metformin on all other parameters was more pronounced in old-aged rats. Metformin caused a significant increase in the PMRS activity in young rats, however, the effect was less pronounced in old rats. These findings provide evidence with respect to restoration of antioxidant status in aged rats after short-term metformin treatment. The findings substantiate the putative antiaging role of metformin.

Effects of statin use on volumetric mammographic density: results from the KARMA study

Background

Epidemiological data on statins and breast cancer risk have been inconclusive. The aim of this study was to clarify the role of statins in breast cancer risk by studying their effect on mammographic density.

Methods

The KARolinska MAmmography project for risk prediction of breast cancer (KARMA) includes 70,877 women who underwent either a screening or clinical mammography from January 2011 to December 2013. In total, 41,102 women responded to a web-based questionnaire, and had raw digital mammograms stored. Volumetric mammographic density was measured using Volpara™ and information on statin use was obtained through linkage with the Swedish National Prescription Register. Analysis of covariance was used to study the effect of statin use on mammographic density, adjusting for a large set of potential confounders. We also studied the effects of statin class and treatment duration and tested for potential effect modification by hormone replacement therapy (HRT).

Results

Statin use was recorded in 3,337 women (8.1 %) of the study population and lipophilic statins was the most commonly prescribed type (93.4 % of all statin users). After multivariable adjustment, percent dense volume was lower in statin users than in non-users (P < 0.001). This association was explained by a larger absolute non-dense volume in statin users (P < 0.001). Overall, no difference in absolute dense volume was detected, but interaction analyses revealed a larger dense volume among statin users who reported ever HRT use (P = 0.03). No differential effects were observed according to statin lipophilicity and treatment duration.

Conclusions

We observed no overall effect of statin use on mammographic density in terms of absolute dense volume, although a larger absolute dense volume was observed in statin users who reported ever HRT use, which requires further investigation.

Association of the metformin with the risk of lung cancer: a meta-analysis

OBJECTIVE

To assess the correlation between metformin and risk of developing lung cancer by meta-analysis.

METHODS

Papers on the correlation between metformin and risk of lung cancer were searched from PubMed, MEDLINE, EMBASE, ISI Web of Science, and Cochrane Library.

RESULTS

Six papers on case-control study were included in this study, involving 39,787 metformin users and 177,752 controls. Meta-analysis showed that the risk of developing lung cancer was lower in metformin users than in those without metformin (OR=0.55, 95% CI: 0.35-0.85, P<0.001).

CONCLUSIONS

The risk of developing lung cancer is lower in metformin users than in those without metformin.

Changes in Components, Glycyrrhizin and Glycyrrhetinic Acid, in RawGlycyrrhiza uralensisFisch, Modify Insulin Sensitizing and Insulinotropic Actions

We hypothesized that roasted Glycyrrhizae Radix (Glycyrrhizin Radix Praeparata, GRP) might modify anti-diabetic action due to compositional changes. Then we examined the anti-diabetic effect and mechanism of raw Glycyrrhizae Radix (GR) and GRP extracts and their major respective components, glycyrrhizin and glycyrrhetinic acid. In partial pancreatectomized (Px) diabetic mice, both GR and GRP improved glucose tolerance, but only GRP enhanced glucose-stimulated insulin secretion as much as exendin-4. Both GR and GRP extracts enhanced insulin-stimulated glucose uptake through peroxisome proliferation-activated receptor (PPAR)-gamma activation in 3T3-L1 adipocytes. Consistently with the results of the mice study, only GRP and glycyrrhetinic acid enhanced glucose-stimulated insulin secretion in isolated islets. In addition, they induced mRNA levels of insulin receptor substrate-2, pancreas duodenum homeobox-1, and glucokinase in the islets, which contributed to improving beta-cell viability. In conclusion, GRP extract containing glycyrrhetinic acid improved glucose tolerance better than GR extract by enhancing insulinotropic action. Thus, GRP had better anti-diabetic action than GR.

Statins: perspectives in cancer therapeutics

Virtually any cell type in a mammalian organism uses Acetyl CoA to yield mevalonate, through the activity of the 3-hydroxy-3-methyl-glutaryl-CoA reductase enzyme and, ultimately, cholesterol. Statins have long and quite successfully been used as cholesterol lowering drugs. They reversibly inhibit the 3-hydroxy-3-methyl-glutaryl-CoA reductase activity, which is rate limiting in the early steps of the cholesterol synthesis pathway. In addition to these effects, it has also been amply shown that statins may efficiently trigger cancer cell apoptosis, making them a plausible therapeutic option for the treatment of cancer. Whether statins may prevent cancer occurrence is a matter of debate and an unanswered question; undoubtedly experimental models have clearly demonstrated the potential of statins as direct cytotoxic agents, which can reduce tumour development or metastasis spread, even more so when combined with cytotoxic drugs. Until now, however, only few data in humans support the idea that statins could rightfully belong to the group of anticancer drugs. Nevertheless, as cancer cell metabolism is being thoroughly revisited, the mevalonate pathway has recently been reported as truly oncogenic, presenting the attractive possibility that mevalonate pathway inhibitors, such as statins, may join the ranks of anticancer drugs.

The key role of growth hormone-insulin-IGF-1 signaling in aging and cancer

Studies in mammals have led to the suggestion that hyperglycemia and hyperinsulinemia are important factors in aging. GH/Insulin/insulin-like growth factor-1 (IGF-1) signaling molecules that have been linked to longevity include daf-2 and InR and their homologues in mammals, and inactivation of the corresponding genes increases lifespan in nematodes, fruit flies and mice. The life-prolonging effects of caloric restriction are likely related to decreasing IGF-1 levels. Evidence has emerged that antidiabetic drugs are promising candidates for both lifespan extension and prevention of cancer. Thus, antidiabetic drugs postpone spontaneous carcinogenesis in mice and rats, as well as chemical and radiation carcinogenesis in mice, rats and hamsters. Furthermore, metformin seems to decrease the risk for cancer in diabetic patients.

Effect of different doses of metformin on serum testosterone and insulin in non-diabetic women with breast cancer: a randomized study

This is a randomized controlled trial to test the effect of different doses of metformin in patients with breast cancer and without diabetes, with the aim of modifying the hormonal and metabolic parameters linked to breast cancer prognosis. Analysis of the results suggest that the dose of 1500 mg/d of metformin causes a significant reduction of insulin and testosterone serum levels.

BACKGROUND

Serum levels of insulin and testosterone may affect both breast cancer (BC) incidence and prognosis. Metformin reduces hyperglycemia and insulin levels in patients with diabetes. In women without diabetes and with polycystic ovary syndrome, metformin lowers both insulin and testosterone levels. Patients with diabetes who are treated with metformin showed a lower risk of cancer; a protective effect of metformin also was observed for BC. Recently, studies on metformin use for prevention or treatment of BC have been proposed in patients who are not diabetic. The aim of the present study was to test the effect of different doses of metformin on serum levels of insulin and testosterone in those postmenopausal patients with breast cancer and without diabetes who have basal testosterone levels ≥0.28 ng/mL (median value).

PATIENTS AND METHODS

A total of 125 eligible women were initially invited to take metformin 500 mg/d for 3 months. The 108 women who completed the first 3 months were invited to continue the study with metformin 1000 mg/d (500 mg twice a day [b.i.d.]) for 1 month. The women were then randomized into 2 groups, and, for the subsequent 5 months, 1 group increased the dose by taking metformin 1500 mg/d (500 mg 3 times a day [t.i.d.]), and the other group continued with metformin 1000 mg /d (500 [b.i.d.]).

RESULTS

A total of 96 women completed the study: 43 women received 1500 mg/d, and 53 women received 1000 mg/d. The women who took 1500 mg/d showed a significant reduction of insulin level, HOMA-IR index (homeostasis model assessment-insulin resistance index), testosterone level, and free androgen index compared with women treated with 1000 mg/d. After treatment with 1500 mg/d, the insulin level decreased by 25% and the testosterone level decreased by 23%.

CONCLUSION

Both these changes might have a prognostic importance.

Melatonin and metformin inhibit skin carcinogenesis and lipid peroxidation induced by benz(a)pyrene in female mice

Outbred female SHR mice (n=200) were divided at random into 4 groups, 50 per group. Benz(a)pyrene solution in acetone was applied onto a skin site on the back during 26 weeks. In parallel, the animals received melatonin, metformin, or both. Melatonin, metformin, and their combination promoted significant reduction of the number and size of skin tumors. In mice receiving no therapy, benz(a)pyrene applications increased the concentrations of malonic dialdehyde in the serum and skin tumor tissue in comparison with the concentrations in the sera and skin of intact mice. Melatonin, metformin, and their combination normalized LPO level.

The influence of type 2 diabetes and glucose-lowering therapies on cancer risk in the Taiwanese

OBJECTIVE

To investigate the association between type 2 diabetes, glucose-lowering therapies (monotherapy with either metformin, sulphonylurea or insulin) and cancer risk in Taiwan.

METHODS

Using Taiwan's National Health Research Institutes database of 1,000,000 random subjects from 2000-2008, we found 61777 patients with type 2 diabetes (age ≥20 years) and 677378 enrollees with no record of diabetes.

RESULTS

After adjusting for age and sex, we found patients with diabetes to have significantly higher risk of all cancers (OR: 1.176; 95% CI: 1.149-1.204, P < 0.001). Diabetic patients treated with insulin or sulfonylureas had significantly higher risk of all cancers, compared to those treated with metformin (OR: 1.583; 95% CI: 1.389-1.805, P < 0.001 and OR: 1.784; 95% CI: 1.406-2.262, P < 0.001). Metformin treatment was associated with a decreased risk of colon and liver cancer compared to sulphonylureas or insulin treatment. Sulfonylureas treatment was associated with an increased risk of breast and lung cancer compared to metformin therapy.

CONCLUSIONS

Taiwanese with type 2 diabetes are at a high risk of breast, prostate, colon, lung, liver and pancreatic cancer. Those treated with insulin or sulfonylureas monotherapy are more likely to develop colon and liver cancer than those treated with metformin.

Cancer risk associated with use of metformin and sulfonylurea in type 2 diabetes: a meta-analysis

OBJECTIVE

Oral antidiabetic drugs (including metformin and sulfonylurea) may play a role in the relationship between type 2 diabetes and cancer. To quantify the association between metformin and sulfonylurea and the risk of cancer, we performed a meta-analysis of available studies on the issue.

MATERIALS AND METHODS

We performed a MEDLINE search for observational studies that investigated the risk of all cancers and specific cancer sites in relation to use of metformin and/or sulfonylurea among patients with type 2 diabetes mellitus. Fixed- and random-effect models were fitted to estimate the summary relative risk (RR). Between-study heterogeneity was tested using χ(2) statistics and measured with the I(2) statistic. Publication bias was evaluated using funnel plot and Egger's regression asymmetry test.

RESULTS

Seventeen studies satisfying inclusion criteria and including 37,632 cancers were evaluated after reviewing 401 citations. Use of metformin was associated with significantly decreased RR of all cancers (summary RR 0.61, 95% confidence interval [CI] 0.54-0.70), colorectal cancer (0.64, 95% CI 0.54-0.76), and pancreatic cancer (0.38, 95% CI 0.14-0.91). With the exception of colorectal cancer, significant between-study heterogeneity was observed. Evidence of publication bias for metformin-cancer association was also observed. There was no evidence that metformin affects the risk of breast and prostate cancers, nor that sulfonylurea affects the risk of cancer at any site.

CONCLUSIONS

Metformin, but not sulfonylurea, appears to reduce subsequent cancer risk. This has relevant implications in light of the exploding global epidemic of diabetes.

Effect of metformin on survival outcomes in diabetic patients with triple receptor-negative breast cancer

BACKGROUND

Recent observational studies have shown that metformin use in diabetic patients decreases both cancer incidence and mortality. Metformin use is also independently predictive of pathologic complete response. In the current study, the authors explored the association between metformin use and survival outcomes in patients with triple receptor-negative breast cancer (TNBC) who were receiving adjuvant chemotherapy.

METHODS

The Breast Cancer Management System database of The University of Texas MD Anderson Cancer Center identified 1448 women who received adjuvant chemotherapy for TNBC between 1995 and 2007. Patients were categorized by diabetes status and metformin use. The Kaplan-Meier product-limit method was used to calculate distant metastasis-free survival (DMFS), recurrence-free survival (RFS), and overall survival (OS). Cox proportional hazards models were fit to determine the association between metformin use and survival outcomes.

RESULTS

The study cohort was comprised of 63 diabetic patients receiving treatment with metformin, 67 diabetic patients not receiving metformin, and 1318 nondiabetic patients. Patients in the diabetic groups tended to be older (P = .005); more diabetic patients were postmenopausal (P = .0007), black (P = .0001), and obese (P < .0001). At a median follow-up of 62 months, there were no significant differences with regard to 5-year DMFS (P = .23), RFS (P = .38), and OS (P = .58) between the 3 groups. Compared with the metformin group, patients who did not receive metformin (hazard ratio [HR], 1.63; 95% confidence interval [95% CI], 0.87-3.06 [P = .13]) and nondiabetic patients (HR, 1.62; 95% CI, 0.97-2.71 [P = .06]) tended to have a higher risk of distant metastases.

CONCLUSIONS

The findings of the current study suggest that metformin use during adjuvant chemotherapy does not significantly impact survival outcomes in diabetic patients with TNBC.

Pancreatogenic diabetes: special considerations for management

BACKGROUND/AIMS

Pancreatogenic, or type 3c, diabetes (T3cDM) occurs due to inherited or acquired pancreatic disease or resection. Although similar to the more prevalent type 1 and type 2 diabetes, pancreatogenic diabetes has a unique pattern of hormonal and metabolic characteristics and a high incidence of pancreatic carcinoma in the majority of patients with T3cDM. Despite these differences, no guidelines for therapy have been described.

METHODS

Published studies on the prevalence, pathophysiology, and cancer associations of T3cDM were reviewed. The recent studies on the protective role and mechanism of metformin therapy as both an anti-diabetic and anti-neoplastic agent were reviewed, and studies on the cancer risk of other anti-diabetic drugs were surveyed.

RESULTS

T3cDM accounts for 5-10% of Western diabetic populations and is associated with mild to severe disease. Hepatic insulin resistance is characteristic of T3cDM and is caused by deficiencies of both insulin and pancreatic polypeptide. 75% of T3cDM is due to chronic pancreatitis, which carries a high risk for pancreatic carcinoma. Insulin and insulin secretagogue treatment increases the risk of malignancy, whereas metformin therapy reduces it. Pancreatic exocrine insufficiency associated with T3cDM contributes to nutritional deficiencies and the development of metabolic bone disease.

CONCLUSIONS

Until consensus recommendations are reached, the glycemic treatment of T3cDM should avoid insulin and insulin secretagogues if possible. Metformin should be the first line of therapy, and continued if insulin treatment must be added for adequate glucose control. Pancreatic enzyme therapy should be added to prevent secondary nutritional and metabolic complications. and IAP.

Diabetes and pancreatic cancer: chicken or egg?

OBJECTIVES

Although half of all patients with pancreatic cancer are diabetic at the time of diagnosis, it remains unclear whether the diabetes associated with pancreatic cancer is a cause or an effect of the malignancy.

METHODS

Epidemiologic studies were reviewed, the geographic prevalence of diabetes and the incidence of pancreatic cancer were examined, and clinical and laboratory studies were reviewed.

RESULTS

Long-standing diabetes increases the risk of pancreatic cancer by 40% to 100%, and recent-onset diabetes is associated with a 4- to 7-fold increase in risk, such that 1% to 2% of patients with recent-onset diabetes will develop pancreatic cancer within 3 years. Treatment of diabetes or morbid obesity decreases the risk of pancreatic cancer, and metformin therapy decreases the risk due to both its antidiabetic and antineoplastic effects. Recent-onset diabetes associated with pancreatic cancer likely represents secondary or type 3 diabetes. The discrimination of type 3 diabetes from the more prevalent type 2 diabetes may identify the high-risk subgroup of diabetic patients in whom potentially curable pancreatic cancer may be found.

CONCLUSIONS

Type 2 and type 1 diabetes mellitus increase the risk of pancreatic cancer with a latency period of more than 5 years. Type 3 diabetes mellitus is an effect, and therefore a harbinger, of pancreatic cancer in at least 30% of patients.

Gender differences in metformin effect on aging, life span and spontaneous tumorigenesis in 129/Sv mice

Studies in mammals have led to the suggestion that hyperglycemia and hyperinsulinemia are important factors both in aging and in the development of cancer. It is possible that the life-prolonging effects of calorie restriction are due to decreasing IGF-1 levels. A search of pharmacological modulators of insulin/IGF-1 signaling pathway (which mimetic effects of life span extending mutations or calorie restriction) could be a perspective direction in regulation of longevity. Antidiabetic biguanides are most promising among them. The chronic treatment of inbred 129/Sv mice with metformin (100 mg/kg in drinking water) slightly modified the food consumption but failed to influence the dynamics of body weight, decreased by 13.4% the mean life span of male mice and slightly increased the mean life span of female mice (by 4.4%). The treatment with metformin failed influence spontaneous tumor incidence in male 129/Sv mice, decreased by 3.5 times the incidence of malignant neoplasms in female mice while somewhat stimulated formation of benign vascular tumors in the latter.

If started early in life, metformin treatment increases life span and postpones tumors in female SHR mice

Hyperglycemia and hyperinsulinemia accelerate both aging and cancer. Antidiabetic biguanides such as metformin decrease glucose, insulin and IGF-1 level. Metformin increases lifespan and prevents cancer in mice, although its effects vary, depending on mice strain and gender. Here we showed that chronic treatment of female outbred SHR mice with metformin started at the age of 3, 9 or 15 months decreased body temperature and postponed age-related switch-off of estrous function. Surprisingly, metformin did not affect levels of serum cholesterol, triglycerides, glucose and insulin. Treatment with metformin started at the age of 3 months increased mean life span by 14% and maximum life span by 1 month. The treatment started at the age of 9 months insignificantly increased mean life span by only 6%, whereas the treatment started at the age of 15 months failed to increase life span. The mean life span of tumor-free mice was increased by 21% in 'the youngest group', by 7% in 'middle-aged group' and in contrast was reduced by 13% in 'the oldest group'. When started at the age of 3 and 9 months, metformin delayed the first tumor detection by 22% and 25%, correspondingly. Thus, in female SHR mice, metformin increased life span and postponed tumors when started at the young and middle but not at the old age. In contrast, metformin improves reproductive function when started at any age.

Modern approach to metabolic rehabilitation of cancer patients: biguanides (phenformin and metformin) and beyond

Comparing the experience accumulated for more than 40 years in the Laboratory of Endocrinology of Petrov Institute of Oncology (St Petersburg, Russia) with similar approaches practiced elsewhere, evidence supports the reasonability of metabolic rehabilitation of patients suffering from breast cancer or other hormone-dependent malignancies. The primary objective of such approaches is to improve treatment results by ameliorating hormonal-metabolic disturbances, including excess body fat, glucose intolerance, insulin resistance and manifestations of endocrine-genotoxic switchings, and modify tissue and cellular targets or mechanisms related or nondirectly related to the aforementioned disturbances. The relevant measures may be categorized as pharmacological (antidiabetic biguanides exemplified with metformin being most popular but not exclusive) and nonpharmacological (rational nutrition, moderate physical activity and so forth) and used separately or in different combinations.

Biogerontology in Russia: from past to future

The paper presents major steps of gerontology development in Russia. The issues of training in gerontology and geriatrics, institutional infrastructure within the Gerontological Society of the Russian Academy of Sciences and its activities have been considered therein. Some results of Russian researchers obtained during 2005-2010 have been summarized as well. Special attention is given to the prospects of gerontology in Russia.

Metformin for aging and cancer prevention

Studies in mammals have led to the suggestion that hyperglycemia and hyperinsulinemia are important factors in aging. Insulin/insulin-like growth factor 1 (IGF-1) signaling molecules that have been linked to longevity include daf-2 and InR and their homologues in mammals, and inactivation of the corresponding genes increases life span in nematodes, fruit flies and mice. It is possible that the life-prolonging effect of caloric restriction is due to decreasing IGF-1 levels. Evidence has emerged that antidiabetic drugs are promising candidates for both life span extension and prevention of cancer. Thus, antidiabetic drugs postpone spontaneous carcinogenesis in mice and rats, as well as chemical and radiation carcinogenesis in mice, rats and hamsters. Furthermore metformin seems to decrease cancer risk in diabetic patients.

Isolated and combined action of tamoxifen and metformin in wild-type, tamoxifen-resistant, and estrogen-deprived MCF-7 cells

Resistance to tamoxifen (TAM) and aromatase inhibitors represents a major drawback to the treatment of hormone-dependent breast cancer, and strategies to overcome this problem are urgently needed. The anti-diabetic biguanide metformin (MF) exerts pleiotropic effects which could enhance the effectiveness of available hormonal therapies. This study modeled several aspects of hormonal therapy in women and examined the effectiveness of MF under those conditions. For cell growth evaluation, wild-type (wt), TAM-resistant (TAM-R), and long-term estradiol-deprived (LTED) MCF-7 cells, as a model of aromatase inhibitor resistance, were grown in the presence or absence of TAM or MF for 5 days. For immunoblot analysis and aromatase activity measurements, these cells were grown for 48 h. Wild-type and LTED cells were equally sensitive to the growth inhibitory effects of TAM and MF, while TAM-R cells were less sensitive to TAM than to MF. Partial additive effects on cell number of TAM combined with MF were greatest (if compared with isolated TAM action) in TAM-R and LTED cells. In contrast to the decrease in PCNA values in TAM-resistant cells treated with the TAM and MF combination, no other changes were found in the levels of this proliferation marker. These findings suggested a major component of apoptosis in the growth inhibitory effect. This was confirmed with Western blot analysis of PARP and caspase 7 as well as with apoptosis ELISA assay. MF also altered signaling pathways. AMP-kinase was stimulated by MF approximately equally in MCF-7, TAM-R, and LTED cells, while inhibition by biguanide of p-S6K as a downstream target of mTOR was strongest in TAM-R cells. Under the influence of MF, expression of ER-α was decreased in wt MCF-7 cells suggesting possible involvement of this compound in estrogen signaling. Metformin interacts additively with TAM to reduce neoplastic cells growth. The cellular context (including loss of sensitivity to TAM and estrogen deprivation) is of importance in influencing breast cancer responses to MF and to a combination of MF and TAM.

Glucose-lowering agents and cancer mortality rates in type 2 diabetes: assessing effects of time-varying exposure

AIMS/HYPOTHESIS

We explored the relationship between glucose-lowering agents and cancer mortality rates in type 2 diabetes patients, hypothesising a decreased risk of cancer mortality with metformin use and a dose-risk gradient for insulin therapy.

METHODS

This was a population-based cohort study using administrative data from Saskatchewan Health, Canada. We identified new users of metformin or sulfonylureas from 1 January 1991 to 31 December 1996, with follow-up until death, departure from the province or 31 December 1999. Cox regression analyses were used to estimate the HR of death from cancer, accounting for time-varying exposure to metformin, sulfonylurea, and exogenous insulin therapy.

RESULTS

We identified 10,309 new users of metformin or sulfonylurea. The average follow-up was 5.4 (1.9) years, during which 407 (4.0%) cancer deaths occurred. Adjusting for age, sex and chronic disease score, the adjusted HR for metformin use was 0.80 (95% CI 0.65-0.98) compared with sulfonylurea monotherapy users. Adjusted HRs for subsequent insulin use were 2.22 (0.99-5.00), 3.33 (2.26-4.89) and 6.40 (4.69-8.73) for <3, 3 to 11 and > or = 12 insulin dispensations/year, respectively, compared with patients not on insulin. We observed a similar risk gradient among the sub-cohort of new insulin users.

CONCLUSIONS/INTERPRETATION

Our results support previous reports of a decreased risk of cancer outcomes associated with metformin use relative to sulfonylurea monotherapy. We also provide new evidence of a gradient of cumulative insulin dispensations and cancer mortality rates.

More favorable progesterone receptor phenotype of breast cancer in diabetics treated with metformin

The coexistence of type 2 diabetes with breast cancer may result in poorer cancer-related survival due to a number of mediating factors including an alteration of tumor tissue hormonal sensitivity. Previous studies have shown that receptor status of breast tumors in diabetics may be changed; however, the mode of therapy for diabetes was usually ignored. This work presents the results of an analysis of the receptor status of breast carcinomas in 90 postmenopausal women suffering with diabetes mellitus type 2 who had been cured, for not less that 1 year prior to surgery, with different modes of antidiabetic therapy, including a dietary treatment only, sulfonylurea preparations, insulin therapy, and metformin as a monotherapy or in combination with sulfonylurea derivatives. No differences in estrogen receptors occurrence in tumor tissue were found in different treatment groups. The frequency of progesterone receptor-positive mammary carcinomas in women who were treated with metformin, irrespective of whether it was combined with sulfonylurea preparations, was significantly higher than in the sulfonylurea only group (P=0.043) and in the combined group of patients treated with either sulfonylurea or insulin (P=0.041). The exclusion of the patients who received neoadjuvant chemotherapy (24 persons) did not significantly affect the above results. The data may be used as an explanation of the distinctions in cancer characteristics and course between diabetic patients treated with either metformin or sulfonylurea derivatives and insulin.

Antidiabetic therapies affect risk of pancreatic cancer

BACKGROUND & AIMS

Antidiabetic drugs have been found to have various effects on cancer in experimental systems and in epidemiologic studies, although the association between these therapeutics and the risk of human pancreatic cancer has not been explored. We investigated the effect of antidiabetic therapies on the risk of pancreatic cancer.

METHODS

A hospital-based case-control study was conducted at M. D. Anderson Cancer Center from 2004 to 2008 involving 973 patients with pancreatic adenocarcinoma (including 259 diabetic patients) and 863 controls (including 109 diabetic patients). Information on diabetes history and other risk factors was collected by personal interview. The frequencies of use of insulin, insulin secretagogues, metformin, and other antidiabetic medications among diabetic patients were compared between cases and controls. The risk of pancreatic cancer was estimated using unconditional logistic regression analysis.

RESULTS

Diabetic patients who had taken metformin had a significantly lower risk of pancreatic cancer compared with those who had not taken metformin (odds ratio, 0.38; 95% confidence interval, 0.22-0.69; P = .001), with adjustments for potential confounders. This difference remained statistically significant when the analysis was restricted to patients with a duration of diabetes >2 years or those who never used insulin. In contrast, diabetic patients who had taken insulin or insulin secretagogues had a significantly higher risk of pancreatic cancer compared with diabetic patients who had not taken these drugs.

CONCLUSIONS

Metformin use was associated with reduced risk, and insulin or insulin secretagogue use was associated with increased risk of pancreatic cancer in diabetic patients.

Metformin, insulin, breast cancer and more

EVALUATION OF: Goodwin PJ, Pritchard KI, Ennis M, Clemons M, Graham M, Fantus IG: Insulin-lowering effects of metformin in women with early breast cancer. Clin. Breast Cancer 8(6), 501-505 (2008). This paper demonstrates that in breast cancer patients without overt diabetes mellitus, the antidiabetic biguanide metformin at a dose of 1500 mg/day reduces initially increased fasting insulinemia by 22.4% on average, 6 months after the onset of treatment. Since the same authors reported earlier on the association between preoperational insulinemia and breast cancer progression rate, an important conclusion from the above publication was that a Phase III randomized trial of metformin is warranted in order to assess the possible antitumor effect of this preparation. The evaluation presented below briefly addresses the history of the issue and possible targets of metformin effects beside its insulin-related action. It is argued that in selecting breast cancer patients for metformin therapy, one should take into account, along with the standard criteria, the pharmacogenetic aspects, estrogen production and specific features of estrogenic signaling, and also the expression of important metformin targets, including AMP-activated protein kinase, in tumor tissue.

Phenylmethimazole decreases Toll-like receptor 3 and noncanonical Wnt5a expression in pancreatic cancer and melanoma together with tumor cell growth and migration

PURPOSE

To evaluate whether (a) Wnt5a expression in pancreatic cancer and malignant melanoma cells might be associated with constitutive levels of Toll-like receptor 3 (TLR3) and/or TLR3 signaling; (b) phenylmethimazole (C10), a novel TLR signaling inhibitor, could decrease constitutive Wnt5a and TLR3 levels together with cell growth and migration; and (c) the efficacy of C10 as a potential inhibitor of pancreatic cancer and malignant melanoma cell growth in vivo.

EXPERIMENTAL DESIGN

We used a variety of molecular biology techniques including but not limited to PCR, Western blotting, and ELISA to evaluate the presence of constitutively activated TLR3/Wnt5a expression and signaling. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-based technology and scratch assays were used to evaluate inhibition of cell growth and migration, respectively. TLR3 regulation of cell growth was confirmed using small interfering RNA technology. Nude and severe combined immunodeficient mice were implanted with human pancreatic cancer and/or melanoma cells and the effects of C10 on tumor growth were evaluated.

RESULTS

We show that constitutive TLR3 expression is associated with constitutive Wnt5a in human pancreatic cancer and malignant melanoma cell lines, that C10 can decrease constitutive TLR3/Wnt5a expression and signaling, suggesting that they are interrelated signal systems, and that C10 inhibits growth and migration in both of these cancer cell lines. We also report that C10 is effective at inhibiting human pancreatic cancer and malignant melanoma tumor growth in vivo in nude or severe combined immunodeficient mice and associate this with inhibition of signal transducers and activators of transcription 3 activation.

CONCLUSIONS

C10 may have potential therapeutic applicability in pancreatic cancer and malignant melanoma.

Relationships between cancer and aging: a multilevel approach

The incidence of cancer increases with age in humans and in laboratory animals alike. There are different patterns of age-related distribution of tumors in different organs and tissues. Aging may increase or decrease the susceptibility of various tissues to initiation of carcinogenesis and usually facilitates promotion and progression of carcinogenesis. Aging may predispose to cancer in two ways: tissue accumulation of cells in late stages of carcinogenesis and alterations in internal homeostasis, in particular, alterations in immune and endocrine systems. Increased susceptibility to the effects of tumor promoters is found both in aged animals and aged humans, as predicted by the multistage model of carcinogenesis. Aging is associated with a number of events at the molecular, cellular and physiological levels that influence carcinogenesis and subsequent cancer growth. An improved understanding of age-associated variables impacting on the tumor microenvironment, as well as the cancer cells themselves, will result in improved treatment modalities in geriatric oncology.

Endocrinology of the wild and mutant BRCA1 gene and types of hormonal carcinogenesis

Information related to the BRCA1 gene has increasingly become a subject for analysis by endocrinologists. For example, it is hard to dismiss the fact that, in BRCA1 mutation carriers, tumors develop predominantly in such estrogen-dependent organs as the mammary glands and ovaries but not in the endometrium. Another characteristic feature is that although BRCA1 mutants and knock-downs are unable to inhibit the transcriptional activity of estrogen receptor-alpha, in BRCA1 mutation carriers breast cancers are often estrogen receptor-negative and originate from the basal rather than the luminal epithelium. The latter, together with other data, suggests that BRCA1-positive breast neoplasms could be considered to be a consequence of the genotoxic variant of hormonal carcinogenesis (that is, associated with DNA damaging rather then with pure hormonal/physiological properties of hormones or their derivatives). Of indisputable significance are the data demonstrating that knocking down of the BRCA1 gene is accompanied by aromatase overexpression and the abolishment of IGF-1 receptor expression suppression, thus increasing both steroid and insulin signaling. Importantly, the endocrine-genotoxic 'liberation' found upon transfer from the wild-type to the mutant BRCA1 provides grounds to regard BRCA1 as a modulator of endocrine-genotoxic switching (predominantly into a direction of DNA-damaging hormone effects) and also to ask whether this is a property of only this or some other tumor suppressor's.

Cancer and ageing: convergent and divergent mechanisms

Cancer and ageing are both fuelled by the accumulation of cellular damage. Consequently, those mechanisms that protect cells from damage simultaneously provide protection against cancer and ageing. By contrast, cancer and longevity require a durable cell proliferation potential and, therefore, those mechanisms that limit indefinite proliferation provide cancer protection but favour ageing. The overall balance between these convergent and divergent mechanisms guarantees fitness and a cancer-free life until late adulthood for most individuals.

Biology of aging and cancer

BACKGROUND

The incidence of cancer increases with age in both humans and laboratory animals. A clear understanding of the causes of the age-related increase in cancer incidence is needed to develop a strategy for primary cancer prevention.

METHODS

We summarized the data available in the literature and our own experience in hormonal metabolic shifts in organisms and disturbances at tissue and cellular levels observed in natural aging and in different types of carcinogenesis in vivo.

RESULTS

There are incongruent patterns of age-related distribution of tumors in different organs and tissues. Aging may increase or decrease the susceptibility of various tissues to initiation of carcinogenesis and usually facilitates promotion and progression of carcinogenesis. Aging may predispose to cancer by at least two mechanisms: tissue accumulation of cells in late stages of carcinogenesis and alterations in internal homeostasis, in particular, alterations in immune and endocrine system. Increased susceptibility to the effects of tumor promoters is found in both aged animals and aged humans, as predicted by the multistage model of carcinogenesis.

CONCLUSIONS

Aging is associated with a number of events at the molecular, cellular and physiologic levels that influence carcinogenesis and subsequent cancer growth. A clearer understanding of these events will help in predicting and treating cancer more effectively.

Signs of proinflammatory/genotoxic switch (adipogenotoxicosis) in mammary fat of breast cancer patients: Role of menopausal status, estrogens and hyperglycemia

The abundance of fat tissue surrounding normal and malignant epithelial mammary cells raises the questions whether such "adipose milieu" is important in the local proinflammatory/genotoxic shift, which apparently promotes tumor development and worsens prognosis, and what conditions stimulate this shift, or "adipogenotoxicosis." We studied 95 mammary fat samples from 70 postmenopausal and 25 premenopausal breast cancer (BC) patients at a distance of 1.5-2.0 cm from tumors. The levels of leptin, adiponectin, TNFalpha and IL-6 release after 4-hr incubation of the samples were evaluated with ELISA, nitric oxide (NO) production by Griess reaction and lipid peroxidation by determination of thiobarbiturate-reactive products (TBRP). Infiltration of fat with macrophages (CD68-positive cells) and expression of cytochrome P450 1B1/estrogen 4-hydroxylase (CYP1B1) were detected by immunohistochemistry. Aromatase (CYP19) activity in mammary fat was measured by (3)H(2)O release from (3)H-1beta-androstenedione. In the postmenopausal BC patients, NO and TNFalpha production by adipose tissue explants increased independent of BMI and in parallel with decreasing leptin and, especially, adiponectin release. In the premenopausal patients, higher CYP1B1 expression and TBRP level were found in mammary fat, while higher aromatase activity was combined with higher CYP1B1 expression as well as NO and IL-6 production. In the postmenopausal group, impaired glucose tolerance was associated with higher IL-6 release production by fat and with higher IL-6/adiponectin ratio. Thus, signs of adipogenotoxicosis in mammary fat can be found in both pre- and postmenopausal BC patients. This condition is likely being maintained through estrogen- and glucose-related factors and mechanisms presumably associated with less favorable types of hormonal carcinogenesis.

Statin therapy in cardiovascular diseases other than atherosclerosis

Statins are drugs that inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, thereby blocking the synthesis of cholesterol. Since being discovered in Japan in the mid 1970s, statins have been widely used to lower low-density lipoprotein cholesterol. However, analysis of cardiovascular research has revealed other important effects beyond changes in lipid parameters, referred to as pleiotropic effects. This paper focuses on the effects of statins as anti-ischemic agents with improvement in endothelial function, along with studies on valvular aortic stenosis, atrial fibrillation, heart failure, peripheral arterial disease, and cancer. As the evolution of statin research continues, there appear to be new potential benefits from statins to be found in many facets of cardiovascular disease.

Cancer in rodents: does it tell us about cancer in humans?

Information obtained from animal models (mostly mice and rats) has contributed substantially to the development of treatments for human cancers. However, important interspecies differences have to be taken into account when considering the mechanisms of cancer development and extrapolating the results from mice to humans. Comparative studies of cancer in humans and animal models mostly focus on genetic factors. This review discusses the bio-epidemiological aspects of cancer manifestation in humans and rodents that have been underrepresented in the literature.

Effect of metformin on life span and on the development of spontaneous mammary tumors in HER-2/neu transgenic mice

Studies in mammals have led to the suggestion that hyperglycemia and hyperinsulinemia are important factors both in aging and in the development of cancer. Insulin/insulin-like growth factor 1 (IGF-1) signaling molecules that have been linked to longevity include DAF-2 and InR and their homologues in mammals, and inactivation of the corresponding genes is followed by increased life span in nematodes, fruit flies and mice. It is possible that the life-prolonging effects of calorie restriction are due to decreasing IGF-1 levels. A search of pharmacological modulators of insulin/IGF-1 signaling pathway (which mimetic effects of life span extending mutations or calorie restriction) could be a perspective direction in regulation of longevity. The chronic treatment of female transgenic HER-2/neu mice with metformin (100 mg/kg in drinking water) slightly decreased the food consumption but failed in reducing the body weight or temperature, slowed down the age-related rise in blood glucose and triglycerides level, as well as the age-related switch-off of estrous function, prolonged the mean life span by 8% (p < 0.05), the mean life span of last 10% survivors by 13.1%, and the maximum life span by 1 month in comparison with control mice. The demographic aging rate represented by the estimate of respective Gompertz's parameter was decreased 2.26 times. The metformin-treatment significantly decreased the incidence and size of mammary adenocarcinomas in mice and increased the mean latency of the tumors.