Metformin as an adjuvant treatment for cancer: a systematic review and meta-analysis

Metformin alters therapeutic effects in the BALB/c tumor therapy model

BACKGROUND

Despite considerable medical proceedings, cancer is still a leading cause of death. Major problems for tumor therapy are chemoresistance as well as toxic side effects. In recent years, the additional treatment with the antidiabetic drug metformin during chemotherapy showed promising results in some cases. The aim of this study was to develop an in vitro tumor therapy model in order to further investigate the potential of a combined chemotherapy with metformin.

METHODS

Cytotoxic effects of a combined treatment on BALB/c fibroblasts were proven by the resazurin assay. Based on the BALB/c cell transformation assay, the BALB/c tumor therapy model was established successfully with four different and widely used chemotherapeutics from different categories. Namely, Doxorubicin as a type-II isomerase inhibitor, Docetaxel as a spindle toxin, Mitomycin C as an alkylating agent and 5-Fluorouracil as an antimetabolite. Moreover, glucose consumption in the medium supernatant was measured and protein expressions were determined by Western Blotting.

RESULTS

Initial tests for the combined treatment with metformin indicated unexpected results as metformin could partly mitigate the cytotoxic effects of the chemotherapeutic agents. These results were further confirmed as metformin induced resistance to some of the drugs when applied simultaneously in the tumor therapy model. Mechanistically, an increased glucose consumption was observed in non-transformed cells as well as in the mixed population of malignant transformed cell foci and non-transformed monolayer cells, suggesting that metformin could also increase glucose consumption in transformed cells.

CONCLUSION

In conclusion, this study suggests a cautious use of metformin during chemotherapy. Moreover, the BALB/c tumor therapy model offers a potent tool for further mechanistic studies of drug-drug interactions during cancer therapy.

Metformin treatment response is dependent on glucose growth conditions and metabolic phenotype in colorectal cancer cells

Cancer cells exhibit altered metabolism, a phenomenon described a century ago by Otto Warburg. However, metabolic drug targeting is considered an underutilized and poorly understood area of cancer therapy. Metformin, a metabolic drug commonly used to treat type 2 diabetes, has been associated with lower cancer incidence, although studies are inconclusive concerning effectiveness of the drug in treatment or cancer prevention. The aim of this study was to determine how glucose concentration influences cancer cells' response to metformin, highlighting why metformin studies are inconsistent. We used two colorectal cancer cell lines with different growth rates and clinically achievable metformin concentrations. We found that fast growing SW948 are more glycolytic in terms of metabolism, while the slower growing SW1116 are reliant on mitochondrial respiration. Both cell lines show inhibitory growth after metformin treatment under physiological glucose conditions, but not in high glucose conditions. Furthermore, SW1116 converges with SW948 at a more glycolytic phenotype after metformin treatment. This metabolic shift is supported by changed GLUT1 expression. Thus, cells having different metabolic phenotypes, show a clear differential response to metformin treatment based on glucose concentration. This demonstrates the importance of growth conditions for experiments or clinical studies involving metabolic drugs such as metformin.

Phenylethynylbenzyl-modified biguanides inhibit pancreatic cancer tumor growth

We present the design and synthesis of a small library of substituted biguanidium salts and their capacity to inhibit the growth of pancreatic cancer cells. We first present their in vitro and membrane activity, before we address their mechanism of action in living cells and in vivo activity. We show that phenylethynyl biguanidium salts possess higher ability to cross hydrophobic barriers, improve mitochondrial accumulation and anticancer activity. Mechanistically, the most active compound, 1b, like metformin, activated AMPK, decreased the NAD⁺/NADH ratio and mitochondrial respiration, but at 800-fold lower concentration. In vivo studies show that compound 1b significantly inhibits the growth of pancreatic cancer xenografts in mice, while biguanides currently in clinical trials had little activity.

Metformin, Microbiome and Protection Against Colorectal Cancer

Metformin is widely used as a firstline therapy to improve insulin sensitivity in type 2 diabetes mellitus (T2DM) patients. This is achieved primarily through regulating AMP-activated protein kinase (AMPK)-dependent pathways leading to reduced hepatic gluconeogenesis and improved muscular uptake of glucose. Epidemiological studies first recognized a relationship with metformin use in T2DM patients and reduced colorectal cancer (CRC) risk. Thereafter, metformin has gained wide attention as a candidate CRC chemopreventative agent; however, the molecular mechanisms underlying its gastrointestinal anti-cancer properties appear multi-faceted and are not well understood. An intriguing area of research is the growing evidence of metformin's metabolic juncture with gut microbiota at the intestinal mucosal interface. This review examines the mechanistic evidence which may account for metformin's protection against CRC through interactions between the drug, gut microbiota and the colonic epithelial mucosa.

Exploring the effect of Gupi Xiaoji Prescription on hepatitis B virus-related liver cancer through network pharmacology and in vitro experiments

AIM AND OBJECTIVE

To study the effect of Gupi Xiaoji Prescription (GXP) on hepatitis B virus(HBV)-related liver cancer through network pharmacology coupled with in vitro experiments and explore their related mechanisms.

MATERIALS AND METHODS

Gupi Xiaoji Prescription's chemical constituents and the action targets of its six medicinal components were identified using several databases. These included the Traditional Chinese Medicine Systems Pharmacology Database （TCMSP), the Bioinformatics Analysis Tool for Molecular mechANism of TCM (BATMAN-TCM), and the Traditional Chinese Medicine Integrated Database (TCMID), while GeneCards and OMIM were used to compile relevant liver cancer disease targets. Pathway enrichment of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), analysis of potential targets, and analysis of the enriched pathways in literature were executed in R. The Hepatocellular carcinoma (HCC)-derived HepG2.2.15 cell line stably expresses and replicates HBV. In vitro experiments with HepG2.2.15 were used to verify GXP's effects on HBV-related liver cancer, while the human liver cancer cell line HepG2 was used as the control.

RESULTS

171 active ingredients and 259 potential drug targets were screened from GXP, involving 181 pathways in vitro. These assays identified Polyphyllin I as an effective GXP component. Notably, GXP inhibited cell proliferation and metastasis in a concentration-dependent manner (P < 0.01). In comparison with the vehicle group, the fluorescence intensity of each drug group was significantly weakened (P < 0.01), while the drug group Mitofusins 1(MFN1) and protein expression level of Mitofusins 2 (MFN2) increased significantly. The protein expression level of Mitochondrial fission protein 1 (FIS1) and Optic Atrophy 1 (OPA1) also showed significant decreases (P < 0.01). Molecular docking revealed Fructus saponins I's high affinity with FIS1, MFN1, MFN2, and OPA1.

CONCLUSION

The network pharmacology results indicate that Gupi Xiaoji Prescription may treat liver cancer by regulating mitochondrial division and fusion of key genes to disrupt liver cancer cells' energy metabolism. In vitro experiments also verified that GXP could inhibit the proliferation and migration of HepG2.2.15 cells by up-regulating MFN1 and MFN2, down-regulating the expression of FIS1 and OPA1 in addition to damaging mitochondria. Consistent with network pharmacology and molecular docking results, Polyphyllin I may be the most active compound of the formula's components. It also shows that Traditional Chinese medicine (TCM) plays a significant, targeted role in the treatment of HBV-related liver cancer.

Targeting nutrient metabolism with FDA-approved drugs for cancer chemoprevention: Drugs and mechanisms

Proliferating cancer cells exhibit metabolic alterations and specific nutritional needs for adapting to their rapid growth. These changes include using aerobic glycolysis, lipid metabolic disorder, and irregular protein degradation. It may be useful to target metabolic abnormalities for cancer chemoprevention. Epidemiological and mechanism-related studies have indicated that many FDA-approved anti-metabolic drugs decrease tumor risk, inhibit tumor growth, or enhance the effect of chemotherapeutic drugs. Drugs targeting nutrient metabolism have fewer side effects with long-term use compared to chemotherapeutic drugs. The characteristics of these drugs make them promising candidates for cancer chemoprevention. Here, we summarize recent discoveries of the chemo-preventive effects of drugs targeting nutrient metabolic pathways and discuss future applications and challenges. Understanding the effects and mechanisms of anti-metabolic drugs in cancer has important implications for exploring strategies for cancer chemoprevention.

How far along are we in revealing the connection between metformin and colorectal cancer?

Colorectal cancer (CRC) is among the most prevalent cancers worldwide, and its prevention and reduction of incidence is imperative. The presence of diabetes has been associated with a 30% increased risk of CRC, likely through the mechanism of hyperinsulinemia, which promotes tumorigenesis via the insulin receptor in the epithelium or by insulin-like growth factor pathways, inflammation, or adipokines, inducing cancer cell proliferation and cancer spread. Metformin, the first-line agent in treating type 2 diabetes, has a chemopreventive role in CRC development. Additionally, preclinical studies suggest synergistic effects of metformin with oxaliplatin in inhibiting in vitro models of colon cancer. Although preclinical studies on the post diagnostic use of metformin were promising and suggested its synergistic effects with chemotherapy, the data on the possible effects of metformin after surgery and other CRC treatment in the clinical setting are less conclusive, and randomized controlled trials are still lacking.

The Influence of Anti-Diabetic Drugs on Prostate Cancer

The incidences of prostate cancer (PC) and diabetes are increasing, with a sustained trend. The occurrence of PC and type 2 diabetes mellitus (T2DM) is growing with aging. The correlation between PC occurrence and diabetes is noteworthy, as T2DM is correlated with a reduced risk of incidence of prostate cancer. Despite this reduction, diabetes mellitus increases the mortality in many cancer types, including prostate cancer. The treatment of T2DM is based on lifestyle changes and pharmacological management. Current available drugs, except insulin, are aimed at increasing insulin secretion (sulfonylureas, incretin drugs), improving insulin sensitivity (biguanides, thiazolidinediones), or increasing urinary glucose excretion (gliflozin). Comorbidities should be taken into consideration during the treatment of T2DM. This review describes currently known information about the mechanism and impact of commonly used antidiabetic drugs on the incidence and progression of PC. Outcomes of pre-clinical studies are briefly presented and their correlations with available clinical trials have also been observed. Available reports and meta-analyses demonstrate that most anti-diabetic drugs do not increase the risk during the treatment of patients with PC. However, some reports show a potential advantage of treatment of T2DM with specific drugs. Based on clinical reports, use of metformin should be considered as a therapeutic option. Moreover, anticancer properties of metformin were augmented while combined with GLP-1 analogs.

Incident Type 2 Diabetes Duration and Cancer Risk: A Prospective Study in Two US Cohorts

BACKGROUND

The influence of type 2 diabetes mellitus (T2D) duration on cancer incidence remains poorly understood.

METHODS

We prospectively followed for cancer incidence 113 429 women in the Nurses' Health Study (1978-2014) and 45 604 men in the Health Professionals Follow-up Study (1988-2014) who were free of diabetes and cancer at baseline. Cancer incidences were ascertained by review of medical records.

RESULTS

In the multivariable-adjusted model incident, T2D was associated with higher risk of cancers in the colorectum, lung, pancreas, esophagus, liver, thyroid, breast, and endometrium. The pooled hazard ratios (HRs) ranged from 1.21 (95% confidence interval [CI] = 1.06 to 1.38) for colorectal cancer to 3.39 (95% CI = 2.24 to 5.12) for liver cancer. For both composite cancer outcomes and individual cancers, the elevated risks did not further increase after 8 years of T2D duration. The hazard ratio for total cancer was 1.28 (95% CI = 1.17 to 1.40) for T2D duration of 4.1-6.0 years, 1.37 (95% CI = 1.25 to 1.50) for 6.1-8.0 years, 1.21 (95% CI = 1.09 to 1.35) for 8.1-10.0 years, and 1.04 (95% CI = 0.95 to 1.14) after 15.0 years. In a cross-sectional analysis, a higher level of plasma C-peptide was found among participants with prevalent T2D of up to 8 years than those without T2D, whereas a higher level of HbA1c was found for those with prevalent T2D of up to 15 years.

CONCLUSIONS

Incident T2D was associated with higher cancer risk, which peaked at approximately 8 years after diabetes diagnosis. Similar duration-dependent pattern was observed for plasma C-peptide. Our findings support a role of hyperinsulinemia in cancer development.

Metformin in the era of new antidiabetics

Type II diabetes mellitus is a known cardiovascular risk factor and its prevalence continues to increase. A revolution in the Type II diabetes mellitus treatment has occurred with the arrival of new antidiabetic drugs, which are thought to compromise metformin place. We aim to review the pharmacology, available evidence and clinical aspects of metformin use in the era of new antidiabetics.

The prevalence of secondary neoplasms in acromegalic patients: possible preventive and/or protective role of metformin

Background

Acromegaly is a rare disease due to chronic growth hormone (GH) excess and the consequent increase in insulin-like growth factor-1 (IGF-1) levels. Both GH and IGF-1 play a role in intermediate metabolism affecting glucose homeostasis. The association between hyperinsulinemia/impaired glucose tolerance and an increased risk of cancer has been clarified. Insulin has a mitogenic effect through its interaction with the IGF-1 receptor (IGF-1R) that also binds IGF-1. On the other hand, metformin, an anti-hyperglycemic drug that decreases serum levels of insulin and IGF-1, could have a protective role in the treatment of endocrine tumors.

Methods

A retrospective, observational, multicenter study in 197 acromegalic patients, receiving/not receiving metformin, was performed to assess whether the prevalence of neoplasms might be correlated with insulin resistance and could eventually be modified by metformin treatment.

Results

In general, the occurrence of secondary neoplasia among our patients was significantly (pV = 0.035) associated with a positive family history of malignancy and with disease duration; a trend towards significance was observed in patients aged > 50 years. Acromegalic subjects who had undergone surgery showed a lower probability of developing a malignant tumor, whereas a higher prevalence of malignancies was observed in obese patients. No significant statistical difference was found when comparing metformin-treated or -untreated subjects for the presence of a second tumor. More interestingly, a trend towards statistical significance (pV = 0.065) was demonstrated in the metformin-treated group for the onset of a benign neoplasm.

Conclusion

Metformin could act directly on tumor cell metabolism and may have an adjuvant role in benign lesion progression.

The Effect of Metformin on Male Reproductive Function and Prostate: An Updated Review

Metformin is the first-line oral antidiabetic drug that shows multiple pleiotropic effects of anti-inflamation, anti-cancer, anti-aging, anti-microbia, anti-atherosclerosis, and immune modulation. Metformin's effects on men's related health are reviewed here, focusing on reproductive health under subtitles of erectile dysfunction (ED), steroidogenesis and spermatogenesis; and on prostate-related health under subtitles of prostate specific antigen (PSA), prostatitis, benign prostate hyperplasia (BPH), and prostate cancer (PCa). Updated literature suggests a potential role of metformin on arteriogenic ED but controversial and contradictory effects (either protective or harmful) on testicular functions of testosterone synthesis and spermatogenesis. With regards to prostate-related health, metformin use may be associated with lower levels of PSA in humans, but its clinical implications require more research. Although there is a lack of research on metform's effect on prostatitis, it may have potential benefits through its anti-microbial and anti-inflammatory properties. Metformin may reduce the risk of BPH by inhibiting the insulin-like growth factor 1 pathway and some but not all studies suggest a protective role of metformin on the risk of PCa. Many clinical trials are being conducted to investigate the use of metformin as an adjuvant therapy for PCa but results currently available are not conclusive. While some trials suggest a benefit in reducing the metastasis and recurrence of PCa, others do not show any benefit. More research works are warranted to illuminate the potential usefulness of metformin in the promotion of men's health.

Association Between Statins and Cancer Incidence in Diabetes: a Cohort Study of Japanese Patients with Type 2 Diabetes

BACKGROUND

The antitumor effect of statins has been highlighted, but clinical study results remain inconclusive. While patients with diabetes are at high risk of cancer, it is uncertain whether statins are effective for cancer chemoprevention in this population.

OBJECTIVE

This study evaluated the association between statins and cancer incidence/mortality in patients with type 2 diabetes.

DESIGN

This study was a follow-up observational study of the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes (JPAD) trial, which was a randomized controlled trial of low-dose aspirin in Japanese patients with type 2 diabetes.

PARTICIPANTS

This study enrolled 2536 patients with type 2 diabetes, age 30-85 years, and no history of atherosclerotic cardiovascular disease, from December 2002 until May 2005. All participants recruited in the JPAD trial were followed until the day of any fatal event or July 2015. We defined participants taking any statin at enrollment as the statin group (n = 650) and the remainder as the no-statin group (n = 1886).

MAIN MEASURES

The primary end point was the first occurrence of any cancer (cancer incidence). The secondary end point was death from any cancer (cancer mortality).

KEY RESULTS

During follow-up (median, 10.7 years), 318 participants developed a new cancer and 123 died as a result. Cancer incidence and mortality were 10.5 and 3.7 per 1000 person-years in the statin group, and 16.8 and 6.3 per 1000 person-years in the no-statin group, respectively. Statin use was associated with significantly reduced cancer incidence and mortality after adjustment for confounding factors (cancer incidence: adjusted hazard ratio [HR], 0.67; 95% CI, 0.49-0.90, P = 0.007; cancer mortality: adjusted HR, 0.60; 95% CI, 0.36-0.98, P = 0.04).

CONCLUSIONS

Statin use was associated with a reduced incidence and mortality of cancer in Japanese patients with type 2 diabetes.

Mechanisms Underlying Hepatocellular Carcinoma Progression in Patients with Type 2 Diabetes

Hepatocellular carcinoma (HCC) ranks third in cancer-related deaths from solid tumors worldwide. The incidence of type 2 diabetes mellitus (T2DM) has increased worldwide in conjunction with the expansion of the Western lifestyle. Furthermore, patients with T2DM have been documented to have an increased risk of HCC, as well as bile tract cancer. Growing evidence shows that T2DM is a strong additive metabolic risk factor for HCC, but how diabetes affects the incidence of HCC requires additional investigation. In this review, we discuss the underlying mechanisms of HCC in patients with T2DM. Topics covered include abnormal glucose and lipid metabolism, hyperinsulinemia, and insulin resistance; the effect of activated platelets; hub gene expression associated with HCC; inflammation and signaling pathways; miRNAs; altered gut microbiota and immunomodulation. The evidence suggests that reducing obesity, diabetes, and nonalcoholic fatty liver disease/nonalcoholic steatohepatitis through efficient measures of prevention may lead to decreased rates of T2DM-related HCC.

The Current and Potential Therapeutic Use of Metformin-The Good Old Drug

Metformin, one of the oldest oral antidiabetic agents and still recommended by almost all current guidelines as the first-line treatment for type 2 diabetes mellitus (T2DM), has become the medication with steadily increasing potential therapeutic indications. A broad spectrum of experimental and clinical studies showed that metformin has a pleiotropic activity and favorable effect in different pathological conditions, including prediabetes, type 1 diabetes mellitus (T1DM) and gestational diabetes mellitus (GDM). Moreover, there are numerous studies, meta-analyses and population studies indicating that metformin is safe and well tolerated and may be associated with cardioprotective and nephroprotective effect. Recently, it has also been reported in some studies, but not all, that metformin, besides improvement of glucose homeostasis, may possibly reduce the risk of cancer development, inhibit the incidence of neurodegenerative disease and prolong the lifespan. This paper presents some arguments supporting the initiation of metformin in patients with newly diagnosed T2DM, especially those without cardiovascular risk factors or without established cardiovascular disease or advanced kidney insufficiency at the time of new guidelines favoring new drugs with pleotropic effects complimentary to glucose control. Moreover, it focuses on the potential beneficial effects of metformin in patients with T2DM and coexisting chronic diseases.

The Role of Metformin in Ovarian Cancer: Does Metformin Increase Survival in Ovarian Neoplasm?

The role of metformin in ovarian cancer (OC) remains a topic of research and open discussion. Because OC has a high mortality rate for various reasons, finding a solution is vital. Although metformin has demonstrated a high level of evidence in preventing and increasing survival in other cancers, its role in OC is still not proven. This review highlights the function of metformin as an antineoplastic agent in OC and its effect on overall survival, progress-free survival, and recurrence-free survival. We conducted a literature search in the PubMed database using the medical subject heading keywords, ovarian neoplasm and metformin. The search yielded 94 articles, of which 86 remained after including only English language articles. Finally, 50 articles published between 1997 and 2020 were reviewed. We recommend more randomized controlled trials in the future to determine the safety and efficacy of metformin in OC.

Pleiotropic Effects of Metformin on the Antitumor Efficiency of Immune Checkpoint Inhibitors

Cancer is an important threat to public health because of its high morbidity and mortality. In recent decades, immune checkpoint inhibitors (ICIs) have ushered a new therapeutic era in clinical oncology. The rapid development of immune checkpoint therapy is due to its inspiring clinical efficacy in a group of cancer types. Metformin, an effective agent for the management of type 2 diabetes mellitus (T2DM), has shown beneficial effects on cancer prevention and cancer treatment. Emerging studies have suggested that metformin in combination with ICI treatment could improve the anticancer effects of ICIs. Hence, we conducted a review to summarize the effects of metformin on ICI therapy. We also review the pleiotropic mechanisms of metformin combined with ICIs in cancer therapy, including its direct and indirect effects on the host immune system.

Multidisciplinary management of endocrinopathies and treatment-related toxicities in patients with Bloom syndrome and cancer

The treatment of malignancy in cancer predisposition syndromes that also confer exquisite sensitivity to standard chemotherapy and radiation regimens remains a challenge. Bloom syndrome is one such disorder that is caused by a defect in DNA repair, predisposing to the development of early-onset age-related medical conditions and malignancies. We report on two patients with Bloom syndrome who responded well to chemotherapy despite significant alterations to standard protocols necessitated by hypersensitivity. Both patients experienced severe toxicities and exacerbation of endocrine comorbidities during chemotherapy. A multidisciplinary team of oncologists and endocrinologists is best suited to care for this patient population.

The Impact of Diabetes Mellitus on the Second Primary Malignancies in Colorectal Cancer Patients

Introduction

All colorectal cancer (CRC) survivors have an increased risk of developing second primary malignancies (SPMs). The association between diabetes mellitus (DM) and the risk of cancer is well known. However, the role of DM and its therapy in the development of SPMs in CRC patients is not well described.

Methods

In this single-institutional retrospective analysis we identified 1,174 colorectal carcinoma patients, median follow-up 10.1 years, (median age 63 years, 724 men). All patients over 18 years with histologically confirmed CRC who were admitted in the period 1.1. 2003- 31.12.2013 and followed-up till 31.12. 2018 at the Masaryk Memorial Cancer Institute (MMCI) were screened for eligibility. The exclusion criteria were CRC diagnosed at autopsy, lost to follow-up and high risk of development of SPMs due to hereditary cancer syndrome. Tumours are considered multiple primary malignancies if arising in different sites and/or are of a different histology or morphology group. Comparisons of the basic characteristics between the patients with SPM and the patients without SPM were performed as well as comparison of the occurrence of SPMs by the site of diagnosis between the DM and non-DM cohorts and survival analyses.

Results

A SPM was diagnosed in 234 (20%) patients, DM in 183 (15%) patients. DM was diagnosed in 22.6% of those with SPM vs. in 13.8% of those without SPM (p=0.001). The most common types of SPMs in DM patients were other CRC, kidney, lung, bladder and nonmelanoma skin cancer, but only carcinoma of the liver and bile duct tracts was significantly more common than in the group without DM. Although breast cancer was the second most common in the group with DM, its incidence was lower than in the group without DM, as well as prostate cancer. A significantly higher incidence of SPMs was found in older CRC patients (≥ 65 years) and in those with lower stage colon cancer and DM. No significant difference in DM treatment between those with and without a SPM was observed including analysis of type of insulin.

Conclusion

CRC patients with diabetes mellitus, especially those with older age, and early stages of colon cancer, should be screened for second primary malignancies more often than the standard population. Patients without DM have longer survival. According to the occurrence of the most common second malignancies, a clinical examination, blood count, and ultrasound of the abdomen is appropriate, together with standard breast and colorectal cancer screening, and lung cancer screening under certain conditions, and should be recommended in CRC survivors especially in patients with intercurrent DM, however the necessary frequency of screening remains unclear.

Inflammatory myofibroblastic tumor successfully treated with metformin: A case report and review of literature

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) is a distinct tumor with a low incidence rate, which can be diagnosed at any age with a predilection for children and adolescents. Although IMT is visible in any tissues and organs, it is more commonly found in the lungs. The clinical and radiological manifestations of IMT lack specificity, hence resulting in frequent misdiagnosis. Surgical resection is currently the main therapeutic approach for IMT. Only scarce cases of IMT treated with metformin have been reported. Here we report the case of an IMT patient with partial penile resection treated with metformin.

CASE SUMMARY

A 1-year-old boy was born with a shorter penis, and his foreskin could not be completely turned over. When he was 6 month old, a well-circumscribed mass on the glans was found, while it did not attract the attention of his parents. The mass gradually increased in size over time before he was admitted to the hospital, where physical examination was performed. It was revealed that the glans hidden behind the foreskin had a mass with a diameter of about 4 cm surrounding the penis. The mass appeared to be hard with a smooth surface and poor mobility. The two testicles examined at the bottom of the scrotum were revealed to have a normal size. Magnetic resonance imaging showed a tumor with rich blood supply encircling the cavernosum with a size of 3.5 cm × 2.1 cm × 2.0 cm. A thick urinary line was found without urine dripping, urgency, and urodynia. Surgical treatment was performed. During the operation, it was observed that the mass had surrounded and invaded the cavernosum without obvious boundaries, and that the tumor occupied about one-half of the penis cross-section as well as infiltrated more than one-half of the glans. In addition, the tumor had caused urethral invasion and anterior urethrostenosis. With the intention of keeping the glans and cavernosum, the tumor at the anterior urethra was partially removed, leaving about 30% of the tumor mass. Pathology analysis demonstrated that the tumor was rich in spindle cells with infiltration of inflammatory cells. Immuno-histochemistry analysis indicated that the cells were positive for CD4, CD99, Ki67, BCL2, and CD68, and negative for ALK, MyoG, S100, SOX10, PR, and EMA. Hence, the tumor was diagnosed as IMT. Metformin was prescribed for the patient after the operation, following which an oral dose of 7 mg/kg was given three times a day after meals. Three months later, it was observed that the remaining tumor had completely disappeared and that the urination process from the urethra opening had resumed normal. In addition, there were no side effects observed. There was also no tumor recurrence. The growth and development of the boy were unaffected as a result of the treatment.

CONCLUSION

The tumor was observed to have completely disappeared after treatment with metformin. Our finding is of great significance to facilitate future clinical treatment with IMT.

Fer and FerT Govern Mitochondrial Susceptibility to Metformin and Hypoxic Stress in Colon and Lung Carcinoma Cells

Aerobic glycolysis is an important metabolic adaptation of cancer cells. However, there is growing evidence that reprogrammed mitochondria also play an important metabolic role in metastatic dissemination. Two constituents of the reprogrammed mitochondria of cancer cells are the intracellular tyrosine kinase Fer and its cancer- and sperm-specific variant, FerT. Here, we show that Fer and FerT control mitochondrial susceptibility to therapeutic and hypoxic stress in metastatic colon (SW620) and non-small cell lung cancer (NSCLC-H1299) cells. Fer- and FerT-deficient SW620 and H1299 cells (SW∆Fer/FerT and H∆Fer/FerT cells, respectively) become highly sensitive to metformin treatment and to hypoxia under glucose-restrictive conditions. Metformin impaired mitochondrial functioning that was accompanied by ATP deficiency and robust death in SW∆Fer/FerT and H∆Fer/FerT cells compared to the parental SW620 and H1299 cells. Notably, selective knockout of the fer gene without affecting FerT expression reduced sensitivity to metformin and hypoxia seen in SW∆Fer/FerT cells. Thus, Fer and FerT modulate the mitochondrial susceptibility of metastatic cancer cells to hypoxia and metformin. Targeting Fer/FerT may therefore provide a novel anticancer treatment by efficient, selective, and more versatile disruption of mitochondrial function in malignant cells.

Metformin exhibits antiproliferation activity in breast cancer via miR-483-3p/METTL3/m6A/p21 pathway

Evidence suggests that metformin might be a potential candidate for breast cancer treatment. Yet, its relevant molecular mechanisms remain to be fully investigated. We found that metformin could suppress the N6-methyladenosine (m6A) level in breast cancer cells significantly. The latter has an essential role in breast cancer progression and is newly considered as a therapeutic target. In this study, we measured the m6A level by m6A colorimetric analysis and dot blot assay. We then performed qRT-PCR, western blot, MeRIP, dual-luciferase reporter assay, and others to explore the m6A-dependent pathway associated with metformin. In vivo effect of metformin was investigated using a mouse tumorigenicity model. In addition, breast cancer and normal tissues were used to determine the role of METTL3 in breast cancer. Metformin could reduce the m6A level via decreasing METTL3 expression mediated by miR-483-3p in breast cancer. METTL3 is known to be able to promote breast cancer cell proliferation by regulating the p21 expression by an m6A-dependent manner. Metformin can take p21 as the main target to inhibit such effect. To specify, this study exhibited that metformin can inhibit breast cancer cell proliferation through the pathway miR-483-3p/METTL3/m6A/p21. Our findings suggest that METTL3 may be considered as a potential therapeutic target of metformin for breast cancer.

Resveratrol, Rapamycin and Metformin as Modulators of Antiviral Pathways

Balanced nutrition and appropriate dietary interventions are fundamental in the prevention and management of viral infections. Additionally, accurate modulation of the inflammatory response is necessary to achieve an adequate antiviral immune response. Many studies, both in vitro with mammalian cells and in vivo with small animal models, have highlighted the antiviral properties of resveratrol, rapamycin and metformin. The current review outlines the mechanisms of action of these three important compounds on the cellular pathways involved with viral replication and the mechanisms of virus-related diseases, as well as the current status of their clinical use.

Longitudinal plasma protein profiling of newly diagnosed type 2 diabetes

BACKGROUND

Comprehensive proteomics profiling may offer new insights into the dysregulated metabolic milieu of type 2 diabetes, and in the future, serve as a useful tool for personalized medicine. This calls for a better understanding of circulating protein patterns at the early stage of type 2 diabetes as well as the dynamics of protein patterns during changes in metabolic status.

METHODS

To elucidate the systemic alterations in early-stage diabetes and to investigate the effects on the proteome during metabolic improvement, we measured 974 circulating proteins in 52 newly diagnosed, treatment-naïve type 2 diabetes subjects at baseline and after 1 and 3 months of guideline-based diabetes treatment, while comparing their protein profiles to that of 94 subjects without diabetes.

FINDINGS

Early stage type 2 diabetes was associated with distinct protein patterns, reflecting key metabolic syndrome features including insulin resistance, adiposity, hyperglycemia and liver steatosis. The protein profiles at baseline were attenuated during guideline-based diabetes treatment and several plasma proteins associated with metformin medication independently of metabolic variables, such as circulating EPCAM.

INTERPRETATION

The results advance our knowledge about the biochemical manifestations of type 2 diabetes and suggest that comprehensive protein profiling may serve as a useful tool for metabolic phenotyping and for elucidating the biological effects of diabetes treatments.

FUNDING

This work was supported by the Swedish Heart and Lung Foundation, the Swedish Research Council, the Erling Persson Foundation, the Knut and Alice Wallenberg Foundation, and the Swedish state under the agreement between the Swedish government and the county councils (ALF-agreement).

Metformin reverses chemoresistance in non-small cell lung cancer via accelerating ubiquitination-mediated degradation of Nrf2

Background

The therapeutic efficacy of cisplatin-based chemotherapy for non-small cell lung cancer (NSCLC) is limited by drug resistance. In NSCLC, hyperactivation of nuclear factor erythroid 2-related factor 2 (Nrf2) counteracts oxidative stress to promote chemoresistance. Metformin-mediated downregulation of Nrf2 plays a pivotal role in overcoming drug resistance in NSCLC cells. Therefore, a deeper understanding of the molecular mechanisms of combination therapy and the role of Nrf2 in chemotherapeutic response is critical to clinical translation.

Methods

The effects of combination therapy with metformin and cisplatin on cell proliferation and apoptosis, intracellular reactive oxygen species (ROS) levels, and xenograft tumor formation were analyzed in NSCLC cells. Co-immunoprecipitation (co-IP) and Phos-tag assays were used to explore the mechanism of metformin-mediated Nrf2 suppression. Immunohistochemical (IHC) staining was performed to detect Nrf2 expression in matched tumor samples before and after neoadjuvant chemotherapy.

Results

Metformin was observed to synergistically augment cisplatin-induced cytotoxicity by strongly inhibiting the level of Nrf2, thereby weakening the antioxidant system and detoxification ability of Nrf2 and enhancing ROS-mediated apoptosis in NSCLC. The synergistic antitumor effect of combination therapy is blocked by treatment with the ROS scavenger N-acetyl cysteine (NAC) as well as overexpression of Nrf2 and its downstream antioxidant protein. Mechanistically, metformin extensively dephosphorylates Nrf2 by attenuating the interaction between Nrf2 and extracellular signal-regulated kinases 1/2 (ERK1/2), which then restores its polyubiquitination and accelerates its proteasomal degradation. Moreover, for the first time, an association of non-decreased Nrf2 expression in patients after neoadjuvant chemotherapy with poor survival and chemoresistance in NSCLC was revealed.

Conclusions

Our findings illustrate the mechanism of metformin-mediated Nrf2 degradation through posttranslational modifications (PTMs), which weakens the ROS defense system in NSCLC. Fluctuations in Nrf2 expression have a strong predictive ability for chemotherapeutic response in neoadjuvant NSCLC patients. Targeting of the Nrf2 pathway could be a therapeutic strategy for overcoming chemoresistance, with metformin as the first choice for this strategy.

Melanotic neuroectodermal tumor of infancy successfully treated with metformin: A case report

RATIONALE

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare tumor originated from neural crest cells with the potential for recurrence and metastasis. The peak age for the disease is during the first year after birth. The current therapy is primarily surgery. The patient reported here is the first case of MNTI treated with metformin.

PATIENT CONCERNS

A case of a 4-month-old infant with a history of swelling in the mouth for 1 month.

DIAGNOSIS

The tumor was diagnosed using radiology, pathology, and immunohistochemistry, and it was performed with complete surgical resection. Unfortunately, the tumor recurred 3 months after surgery.

INTERVENTIONS

We prescribed metformin for the infant.

OUTCOMES

Currently, after 9 months of treatment, the tumor is well controlled without apparent side effects.

LESSONS

The case presented suggested that metformin may be an underlying therapy for MNTI.

The potential adjunctive benefit of adding metformin to standard treatment in inoperable cancer patients: a meta-analysis of randomized controlled trials

Background

Recently, there have been several randomized clinical trials (RCTs) conducted to evaluate the efficacy and safety of metformin plus standard treatment in inoperable cancer patients. Our meta-analysis aimed to assess the efficacy of metformin in combination with standard treatment in inoperable cancer patients.

Methods

PubMed and Embase databases were systematically searched for relevant RCTs investigating the efficacy of adding metformin to standard treatment for cancer patients. The pooled relative risk (RR) for tumor response and safety was calculated to assess the efficacy of combining metformin with standard treatment. Meta-analysis was subsequently performed to pool the hazard ratio (HR) for overall survival (OS) and progression-free survival (PFS).

Results

Ten RCTs comprising 1033 patients were included in our current meta-analysis. In patients with breast cancer, results of meta-analysis showed that the addition of metformin to standard treatment was beneficial to objective response rate (ORR) with 30.3% (33/109) in the metformin plus standard treatment group and 16.1% (18/112) in the placebo group (RR 1.92, 95% CI: 1.19–3.10, P=0.008). OS and PFS were not significantly improved in patients who received metformin plus standard treatment compared with those who received placebo plus standard treatment (OS: HR 1.02, 95% CI: 0.71–1.46, P=0.916; PFS: HR 1.14, 95% CI: 0.86–1.50, P=0.366). For lung cancer patients, meta-analysis results showed adding metformin to standard treatment could benefit ORR (metformin 65.3% vs. placebo 54.6%, RR 1.22, 95% CI: 1.03–1.43, P=0.018) with no significant survival benefit in the metformin group. For patients with pancreatic cancer, the pooled ORR was 17.6% (16/91) in metformin plus standard treatment group and 20% (18/90) in the placebo group, indicating metformin did not benefit ORR (RR 0.85, 95% CI: 0.49–1.49, P=0.576). Besides, the addition of metformin to standard treatment did not increase the incidence rate of adverse effects.

Conclusions

Our results indicated that addition of metformin to standard treatment was beneficial to ORR in inoperable breast or lung cancer patients without increasing the incidence of adverse effects. However, adding metformin to standard treatment could not benefit OS and PFS.

Metformin and everolimus in neuroendocrine tumours: A synergic effect?

OBJECTIVE

To explore potential synergy in effectiveness between metformin and everolimus, 2 inhibitors of the mTOR pathway, for neuroendocrine tumours (NET).

DESIGN AND METHODS

A cohort of patients with advanced gastroenteropancreatic or lung NETs treated by everolimus were stratified in to those without diabetes, those with diabetes and without metformin, and those with diabetes with metformin. The primary endpoint was the median progression-free survival (PFS).

RESULTS

A total of 213 patients were included, 165 of which were non-diabetic; among diabetic patients, 19 were treated with metformin and 29 with others anti-diabetic drugs. No significant difference in median PFS [95%CI] was found between the three groups: 10.05 months [8.27;11.83] for non-diabetic patients, 15.24 [19.88;49.43] for diabetic w/metformin, and 9.03 months [4.01;14.06] for diabetic w/o metformin group. In univariate analysis, factors significantly associated with longer PFS was a functioning NET, a number of metastatic sites<3, the absence of lung metastasis, and an uptake on Octreoscan®, but not the absence of metformin use; only uptake on Octreoscan® remained significant in multivariate analysis.

CONCLUSIONS

In contrast with the literature, we did not find a synergy between everolimus and metformin in NET. Prospective studies are underway to improve the comprehension of the potential synergy regarding population and tumour type.

Metformin as a senostatic drug enhances the anticancer efficacy of CDK4/6 inhibitor in head and neck squamous cell carcinoma

CDK4/6 inhibitors show promising antitumor activity in a variety of solid tumors; however, their role in head and neck squamous cell carcinoma (HNSCC) requires further investigation. The senescence-associated secretory phenotype (SASP) induced by CDK4/6 inhibitors has dual effects on cancer treatment. The need to address the SASP is a serious challenge in the clinical application of CDK4/6 inhibitors. We investigated whether metformin can act as a senostatic drug to modulate the SASP and enhance the anticancer efficacy of CDK4/6 inhibitors in HNSCC. In this study, the efficacy of a combination of the CDK4/6 inhibitor LY2835219 and metformin in HNSCC was investigated in in vitro assays, an HSC6 xenograft model, and a patient-derived xenograft model. Senescence-associated β-galactosidase staining, antibody array, sphere-forming assay, and in vivo tumorigenesis assay were used to detect the impacts of metformin on the senescence and SASP induced by LY2835219. We found that LY2835219 combined with metformin synergistically inhibited HNSCC by inducing cell cycle arrest in vitro and in vivo. Metformin significantly modulated the profiles of the SASP elicited by LY2835219 by inhibiting the mTOR and stat3 pathways. The LY2835219-induced SASP resulted in upregulation of cancer stemness, while this phenomenon can be attenuated when combined with metformin. Furthermore, results showed that the stemness inhibition by metformin was associated with blockade of the IL6-stat3 axis. Survival analysis demonstrated that overexpression of IL6 and stemness markers was associated with poor survival in HNSCC patients, indicating that including metformin to target these proteins might improve patient prognosis. Collectively, our data suggest that metformin can act as a senostatic drug to enhance the anticancer efficacy of CDK4/6 inhibitors by reprogramming the profiles of the SASP.

A risk stratification model based on four novel biomarkers predicts prognosis for patients with renal cell carcinoma

BACKGROUND

Accurate prediction of the prognosis of RCC using a single biomarker is challenging due to the genetic heterogeneity of the disease. However, it is essential to develop an accurate system to allow better patient selection for optimal treatment strategies. ARL4C, ECT2, SOD2, and STEAP3 are novel molecular biomarkers identified in earlier studies as survival-related genes by comprehensive analyses of 43 primary RCC tissues and RCC cell lines.

METHODS

To develop a prognostic model based on these multiple biomarkers, the expression of four biomarkers ARL4C, ECT2, SOD2, and STEAP3 in primary RCC tissue were semi-quantitatively investigated by immunohistochemical analysis in an independent cohort of 97 patients who underwent nephrectomy, and the clinical significance of these biomarkers were analyzed by survival analysis using Kaplan-Meier curves. The prognostic model was constructed by calculation of the contribution score to prognosis of each biomarker on Cox regression analysis, and its prognostic performance was validated.

RESULTS

Patients whose tumors had high expression of the individual biomarkers had shorter cancer-specific survival (CSS) from the time of primary nephrectomy. The prognostic model based on four biomarkers segregated the patients into a high- and low-risk scored group according to defined cut-off value. This approach was more robust in predicting CSS compared to each single biomarker alone in the total of 97 patients with RCC. Especially in the 36 metastatic RCC patients, our prognostic model could more accurately predict early events within 2 years of diagnosis of metastasis. In addition, high risk-scored patients with particular strong SOD2 expression had a much worse prognosis in 25 patients with metastatic RCC who were treated with molecular targeting agents.

CONCLUSIONS

Our findings indicate that a prognostic model based on four novel biomarkers provides valuable data for prediction of clinical prognosis and useful information for considering the follow-up conditions and therapeutic strategies for patients with primary and metastatic RCC.

Targeting Metabolism in Cancer Cells and the Tumour Microenvironment for Cancer Therapy

Targeting altered tumour metabolism is an emerging therapeutic strategy for cancer treatment. The metabolic reprogramming that accompanies the development of malignancy creates targetable differences between cancer cells and normal cells, which may be exploited for therapy. There is also emerging evidence regarding the role of stromal components, creating an intricate metabolic network consisting of cancer cells, cancer-associated fibroblasts, endothelial cells, immune cells, and cancer stem cells. This metabolic rewiring and crosstalk with the tumour microenvironment play a key role in cell proliferation, metastasis, and the development of treatment resistance. In this review, we will discuss therapeutic opportunities, which arise from dysregulated metabolism and metabolic crosstalk, highlighting strategies that may aid in the precision targeting of altered tumour metabolism with a focus on combinatorial therapeutic strategies.

Combination of metformin and RG7388 enhances inhibition of growth and induction of apoptosis of ovarian cancer cells through the PI3K/AKT/mTOR pathway

Ovarian cancer is a gynecological cancer that has the highest mortality rate and is often resistant to conventional treatments. Therefore, development of new therapies is essential. Metformin (MET), which is the priority drug for treatment of type 2 diabetes, has received increasing attention because of its anti-tumor effects. Here, we examined combined anti-tumor effects of MET and RG7388, the only MDM2 (mouse double minute 2 homolog) antagonist that has entered phase III clinical trials, on ovarian cancer cell lines. We examined effects on proliferation by Cell Counting Kit-8 (CCK-8) and colony formation assays, and effects on apoptosis by flow cytometric analysis and Hoechst staining. Western blotting was used to measure protein expression in cells and tissues treated with MET and/or RG7388. Flow cytometry was used to measure reactive oxygen species (ROS). We also examined the effects of MET and/or RG7388 on inhibition of A2780 cell growth in vivo. The combination of MET and RG7388 significantly increased growth inhibition, apoptosis, and ROS of A2780 and SKOV3 cells compared with either agent alone. Additionally, in vitro and in vivo results showed that MET and/or RG7388 inhibited the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway and their combination had a stronger effect. Our findings suggest that the combination of MET and RG7388 enhances growth inhibition and apoptosis induction of ovarian cancer cells through the PI3K/AKT/mTOR pathway and accumulation of intracellular ROS.

Classifying the Linkage between Adipose Tissue Inflammation and Tumor Growth through Cancer-Associated Adipocytes

Recently, tumor microenvironment (TME) and its stromal constituents have provided profound insights into understanding alterations in tumor behavior. After each identification regarding the unique roles of TME compartments, non-malignant stromal cells are found to provide a sufficient tumorigenic niche for cancer cells. Of these TME constituents, adipocytes represent a dynamic population mediating endocrine effects to facilitate the crosstalk between cancer cells and distant organs, as well as the interplay with nearby tumor cells. To date, the prevalence of obesity has emphasized the significance of metabolic homeostasis along with adipose tissue (AT) inflammation, cancer incidence, and multiple pathological disorders. In this review, we summarized distinct characteristics of hypertrophic adipocytes and cancer to highlight the importance of an individual's metabolic health during cancer therapy. As AT undergoes inflammatory alterations inducing tissue remodeling, immune cell infiltration, and vascularization, these features directly influence the TME by favoring tumor progression. A comparison between inflammatory AT and progressing cancer could potentially provide crucial insights into delineating the complex communication network between uncontrolled hyperplastic tumors and their microenvironmental components. In turn, the comparison will unravel the underlying properties of dynamic tumor behavior, advocating possible therapeutic targets within TME constituents.

Metformin Mitigates DPP-4 Inhibitor-Induced Breast Cancer Metastasis via Suppression of mTOR Signaling

The biological influence of antidiabetic drugs on cancer cells and diabetic cancer patients has not yet been completely elucidated. We reported that a dipeptidyl peptidase (DPP)-4 inhibitor accelerates mammary cancer metastasis by inducing epithelial-mesenchymal transition (EMT) through the CXCL12/CXCR4/mTOR axis. Metformin has been shown to inhibit the mTOR signaling pathway. In this study, we investigated whether metformin mitigates breast cancer metastasis induced by a DPP-4 inhibitor via suppression of mTOR signaling. In cultured mouse mammary and human breast cancer cells, metformin suppressed DPP-4 inhibitor KR62436 (KR)-induced EMT and cell migration via suppression of the mTOR pathway associated with AMPK activation. For the in vivo study, metformin intervention was performed in an allograft 4T1 breast cancer model mouse with or without KR. We also analyzed mice transplanted with shRNA-mediated DPP-4 knockdown 4T1 cells. Treatment with metformin inhibited the lung metastasis of DPP-4-deficient 4T1 mammary tumor cells generated by either KR administration or DPP-4 knockdown. Immunostaining of primary tumors indicated that DPP-4 suppression promoted the expression of EMT-inducing transcription factor Snail through activation of the CXCR4-mediated mTOR/p70S6K pathway in an allograft breast cancer model; metformin abolished this alteration. Metformin treatment did not alter DPP-4-deficiency-induced expression of CXCL12 in either plasma or primary tumors. Our findings suggest that metformin may serve as an antimetastatic agent by mitigating the undesirable effects of DPP-4 inhibitors in patients with certain cancers. IMPLICATIONS: Metformin could combat the detrimental effects of DPP-4 inhibitor on breast cancer metastasis via mTOR suppression, suggesting the potential clinical relevance. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/1/61/F1.large.jpg.

Preventative and Therapeutic Effects of Metformin in Gastric Cancer: A New Contribution of an Old Friend

Gastric cancer (GC) is a cancer with high prevalence, and is one of the leading causes of cancer death worldwide. Metformin is a widely used hypoglycemic agent for type-2 diabetes mellitus (T2DM). Recently, metformin has drawn increasing attention in the field of cancer research for its emerging anti-cancer roles. However, the efficacy and underlying molecular mechanisms of metformin in the prevention and treatment for GC remain controversial. This review summarized the present clinical and mechanistic studies that investigated the efficacy of metformin in GC. It was found that the majority of clinical studies affirmed protective roles of metformin in both gastric cancer risk and survival rate. In addition, metformin’s effects in the prevention and treatment for GC involve multiple pathways mainly via AMPK and IGF-1R. It was concluded that metformin presents a unique opportunity for application against GC, but further clinical and mechanistic investigations are required to solidify the roles of metformin in GC.

Mechanisms of metformin inhibiting cancer invasion and migration

Cancer currently ranks among the leading causes of death globally. Cancer invasion and metastasis transform locally grown cancers to a systemic and life-threatening disease, which accounts for the most significant challenge in cancer treatment. Recent studies showed that Metformin, the most commonly used first-line oral drug for the treatment of type 2 diabetes (T2DM), could prevent and treat various cancers. Moreover, multiple evidence suggested that metformin inhibited cancer invasion and metastasis, which could improve the prognosis of cancer patients administrated with metformin. To better understand the anti-cancer role of metformin, the present review summarized the potential mechanisms of inhibiting cancer invasion and metastasis by metformin, including AMPK signaling pathway, EMT signaling pathway, epigenetic modification and so on. However, multiple problems remain unresolved and more clinical trials are needed to prove the inhibition of cancer invasion and metastasis by metformin.

Independent and joint cross-sectional associations of statin and metformin use with mammographic breast density

BACKGROUND

Well-tolerated and commonly used medications are increasingly assessed for reducing breast cancer risk. These include metformin and statins, both linked to reduced hormone availability and cell proliferation or growth and sometimes prescribed concurrently. We investigated independent and joint associations of these medications with mammographic breast density (MBD), a useful biomarker for the effect of chemopreventive agents on breast cancer risk.

METHODS

Using data from a cross-sectional study of 770 women (78% Hispanic, aged 40-61 years, in a mammography cohort with high cardiometabolic burden), we examined the association of self-reported "ever" use of statins and metformin with MBD measured via clinical Breast Imaging Reporting and Data System (BI-RADS) density classifications (relative risk regression) and continuous semi-automated percent and size of dense area (Cumulus) (linear regression), adjusted for age, body mass index, education, race, menopausal status, age at first birth, and insulin use.

RESULTS

We observed high statin (27%), metformin (13%), and combination (9%) use, and most participants were overweight/obese (83%) and parous (87%). Statin use was associated with a lower likelihood of high density BI-RADS (RR = 0.60, 95% CI = 0.45 to 0.80), percent dense area (PD) (β = - 6.56, 95% CI = - 9.05 to - 4.06), and dense area (DA) (β = - 9.05, 95% CI = - 14.89 to - 3.22). Metformin use was associated with lower PD and higher non-dense area (NDA), but associations were attenuated by co-medication with statins. Compared to non-use of either medication, statin use alone or with metformin were associated with lower PD and DA (e.g., β = - 6.86, 95% CI: - 9.67, - 4.05 and β = - 7.07, 95% CI: - 10.97, - 3.17, respectively, for PD) and higher NDA (β = 25.05, 95% CI: 14.06, 36.03; β = 29.76, 95% CI: 14.55, 44.96, respectively).

CONCLUSIONS

Statin use was consistently associated with lower MBD, measured both through clinical radiologist assessment and continuous relative and absolute measures, including dense area. Metformin use was associated with lower PD and higher NDA, but this may be driven by co-medication with statins. These results support that statins may lower MBD but need confirmation with prospective and clinical data to distinguish the results of medication use from that of disease.

Repurposing old drugs to fight multidrug resistant cancers

Overcoming multidrug resistance represents a major challenge for cancer treatment. In the search for new chemotherapeutics to treat malignant diseases, drug repurposing gained a tremendous interest during the past years. Repositioning candidates have often emerged through several stages of clinical drug development, and may even be marketed, thus attracting the attention and interest of pharmaceutical companies as well as regulatory agencies. Typically, drug repositioning has been serendipitous, using undesired side effects of small molecule drugs to exploit new disease indications. As bioinformatics gain increasing popularity as an integral component of drug discovery, more rational approaches are needed. Herein, we show some practical examples of in silico approaches such as pharmacophore modelling, as well as pharmacophore- and docking-based virtual screening for a fast and cost-effective repurposing of small molecule drugs against multidrug resistant cancers. We provide a timely and comprehensive overview of compounds with considerable potential to be repositioned for cancer therapeutics. These drugs are from diverse chemotherapeutic classes. We emphasize the scope and limitations of anthelmintics, antibiotics, antifungals, antivirals, antimalarials, antihypertensives, psychopharmaceuticals and antidiabetics that have shown extensive immunomodulatory, antiproliferative, pro-apoptotic, and antimetastatic potential. These drugs, either used alone or in combination with existing anticancer chemotherapeutics, represent strong candidates to prevent or overcome drug resistance. We particularly focus on outcomes and future perspectives of drug repositioning for the treatment of multidrug resistant tumors and discuss current possibilities and limitations of preclinical and clinical investigations.

Effects of metformin on adipose-derived stromal cell (ADSC) - Breast cancer cell lines interaction

AIMS

Metformin is a clinical drug administered to patients to treat type 2 diabetes mellitus that was found to be associated with a lower risk of occurrence of cancer and cancer-related death. The present study investigated the effects of metformin on human adipose-derived stromal cells (ADSC) - breast cancer cell line interactions.

MAIN METHODS

ADSCs grown from lipoaspirates were tested for growth-stimulating and migration-controlling activity on breast cancer cell lines after pretreatment with metformin. Furthermore, secreted proteins of ADSCs, phosphorylation of intracellular proteins and the effect of metformin on adipocytic differentiation of ADSCs were assayed.

KEY FINDINGS

Compared to breast cancer cell lines (4.0 ± 3.5% reduction of proliferation), 2 mM metformin significantly inhibited the proliferation of ADSC lines (19.2 ± 8.4% reduction of proliferation). This effect on ADSCs seems to be mediated by altered phosphorylation of GSK-3, CREB and PRAS40. Furthermore, treatment with metformin abolished the induction of differentiation of three ADSC lines to adipocytes. 1 and 2 mM metformin significantly impaired the migration of breast cancer cell lines MDA-MB-231 and MDA-MB-436 in scratch assays.

SIGNIFICANCE

Metformin showed low direct inhibitory effects on breast cancer cell lines at physiological concentrations but exerted a significant retardation of the growth and the adipocytic differentiation of ADSCs. Thus, the anticancer activity of metformin in breast cancer at physiological drug concentrations seems to be mediated by an indirect mechanism that lowers the supportive activity of ADSCs.

Metformin fights against radiation-induced early developmental toxicity

Nuclear pollution intertwined accidental irradiation not only triggers acute and chronic radiation syndromes, but also endangers embryonic development in sight of uncontrollable gene mutation. Metformin (MET), a classic hypoglycemic drug, has been identified to possess multiple properties. In this study, we explored the radioprotective effects of MET on the developmental abnormalities and deformities induced by irradiation among three "star drugs". Specifically, zebrafish (Danio rerio) embryos exposed to 5.2 Gy gamma irradiation at 4 h post fertilization (hpf) showed overt developmental toxicity, including hatching delay, hatching rate decrease, developmental indexes reduction, morphological abnormalities occurrence and motor ability decline. However, MET treatment erased the radiation-induced phenotypes. In addition, MET degraded inflammatory reaction, hinders apoptosis response, and reprograms the development-related genes expression, such as sox2, sox3, sox19a and p53, in zebrafish embryos following radiation challenge. Together, our findings provide novel insights into metformin, and underpin that metformin might be employed as a promising radioprotector for radiation-induced early developmental toxicity in pre-clinical settings.

The Impact of Comorbid Diabetes on Short-Term Postoperative Outcomes in Stage I/II Colon Cancer Patients Undergoing Open Colectomy

Purpose

This study aimed at evaluating the impact of comorbid diabetes on short-term postoperative outcomes in patients with stage I/II colon cancer after open colectomy.

Methods

The data were extracted from the National Inpatient Sample database (2005-2010). Short-term surgical outcomes included in-hospital mortality, postoperative complications, and hospital length of stay.

Results

A total of 49,064 stage I/II colon cancer patients undergoing open surgery were included, with a mean age of 70.35 years. Of them, 21.94% had comorbid diabetes. Multivariable analyses revealed that comorbid diabetes was significantly associated with a lower risk of in-hospital mortality and postoperative complications. Compared to patients without diabetes, patients with uncomplicated diabetes had lower percentages of in-hospital mortality and postoperative complications, but patients with complicated diabetes had a higher percentage of postoperative complications. In addition, patients with diabetes only, but not patients with diabetes and hypertension only, had a lower percentage of in-hospital mortality than patients without any comorbidity.

Conclusion

The present results suggested the protective effects of uncomplicated diabetes on short-term surgical outcomes in stage I/II colon cancer patients after open colectomy. Further studies are warranted to confirm these unexpected findings and investigate the possible underlying mechanisms.

The potential role of metformin in the treatment of patients with pancreatic neuroendocrine tumors: a review of preclinical to clinical evidence

The incidence of pancreatic neuroendocrine tumors (panNETs) has increased worldwide in the last two decades. Given the indolent nature of these tumors, several patients are diagnosed with metastatic disease, which partially impairs the long-term efficacy of currently available treatments and reduces survival rates. The search for new therapeutic strategies for cancer patients has pushed towards the retrospective analysis of studies involving patients who concomitantly received other drugs together with standard anticancer agents. In this light, several retrospective analyses have shown that metformin use is associated with improved prognosis in patients with different tumor types treated with standard antitumor agents. Metformin, the cornerstone oral agent for the treatment of type 2 diabetes, plays a role in modulating glucose cell metabolism. Its potential ability to interfere with tumors may derive from the tight relationship between metabolic reprogramming in cancer cells and tumor progression. Indications for metformin use as an anticancer drug result from pre-clinical and clinical observations. In particular, metformin use in diabetic patients with advanced panNETs has been associated with better progression-free survival in patients treated with somatostatin analogues with or without metformin.

Penfluridol triggers mitochondrial-mediated apoptosis and suppresses glycolysis in colorectal cancer cells through down-regulating hexokinase-2

Penfluridol, a commonly used antipsychotic agent in a clinical setting, exhibits potential anticancer properties against various human malignancies. Here, we investigated the effect of penfluridol on the biological behavior of colorectal cancer (CRC) cells. Cell viability and clonogenic potential were detected by the cell counting kit-8 and colony formation assay. The cell apoptosis and cell cycle distribution were quantified through flow cytometry. Caspase-3 activity, glucose consumption, lactate production, and intracellular ATP levels were evaluated using the corresponding commercial detection kits. The protein levels of related genes were detected through western blotting. Mitochondrial membrane potential was detected using JC-1 staining. A CRC xenograft tumor model was used to validate the antitumor activity of penfluridol in vivo. Penfluridol reduced cell survival and promoted apoptotic cell death effectively through the mitochondria-mediated intrinsic pathway in a dose-dependent manner. Furthermore, the process of glycolysis in HCT-116 and HT-29 cells was inhibited upon penfluridol treatment, as evidenced by the decrease in glucose consumption, lactate production, and intracellular ATP levels. Further mechanistic studies revealed that penfluridol influenced cell apoptosis and glycolysis in CRC cells by downregulating hexokinase-2 (HK-2). The proapoptotic effect and glycolytic inhibition-induced by penfluridol were effectively reversed by HK-2 overexpression. Consistent with in vitro results, penfluridol could also suppress tumor growth and trigger apoptosis in vivo. Penfluridol triggers mitochondrial-mediated apoptosis and induces glycolysis inhibition via modulating HK-2 in CRC and provides a theoretical basis to support penfluridol as a repurposed drug for CRC patients.

Metformin Protects ARPE-19 Cells from Glyoxal-Induced Oxidative Stress

The protective effects and mechanisms of metformin against oxidative stress were evaluated both in vivo and in vitro. ARPE-19 cells comprised the normal group, the glyoxal-treated group (0.5 mM glyoxal), and the glyoxal+metformin group (0.5 mM glyoxal and 0.1 mM metformin). In the in vitro model, differences in cell viability, ROS production, NO products, cellular apoptosis, and the expressions of phospho-AMPKα, total-AMPKα, Sirt1, Nrf2, TXNIP, ZO-1, and Occludin were assessed. In the glyoxal-treated group, cell viability and NO production were decreased, while ROS production and cell apoptosis were increased (p < 0.05), compared with the control group. These changes were prevented by metformin treatment. Protein expressions of phospho-AMPKα, Sirt1, TXNIP, ZO-1, and Occludin, but not Nrf2, were decreased significantly in the glyoxal-treated group compared to normal controls. Metformin treatment significantly increased the above protein expressions and slightly increased TXNIP expression. Immunofluorescence showed that metformin prevented the glyoxal-induced, disorganized tight junctions in ARPE-19 cells. To confirm metformin's protection, Sprague-Dawley rats were injected intravenously with sodium iodate (SI) to induce oxidative stress in the retinal pigment epithelium (RPE). Metformin was then delivered intraperitoneally or intravitreally. One day and three days after SI and metformin treatments, the RPE-Bruch's membrane-choriocapillaris complex was isolated and immune-stained with ZO-1 antibodies. The morphology of the RPE showed enlarged cellular bodies and disorganized ZO-1 staining in SI-treated rats. Metformin treatment prevented these changes. The results indicated that metformin maintained the barrier functions of RPE cells both in vivo and in vitro. Metformin exerted its protection against oxidative stress possibly via activating AMPK/Sirt1 and increasing TXNIP. Metformin has been proposed as a candidate drug for age-related macular degeneration (AMD) by both preclinical and clinical studies. The cellular and animal models used in this study might be useful for the interpretation of the molecular mechanisms involved in the drug activity.

Metformin mitigates gastrointestinal radiotoxicity and radiosensitises P53 mutation colorectal tumours via optimising autophagy

BACKGROUND AND PURPOSE

There is an urgent but unmet need for mitigating radiation-induced intestinal toxicity while radio sensitising tumours for abdominal radiotherapy. We aimed to investigate the effects of metformin on radiation-induced intestinal toxicity and radiosensitivity of colorectal tumours.

EXPERIMENTAL APPROACH

Acute and chronic histological injuries of the intestine from mice were used to assess radioprotection and IEC-6 cell line was used to investigate the mechanisms in vitro. The fractionated abdominal radiation model of HCT116 and HT29 tumour grafts was used to determine the effects on colorectal cancer.

KEY RESULTS

Metformin alleviated radiation-induced acute and chronic intestinal toxicity by optimising mitophagy which was AMPK-dependent. In addition, our data indicated that metformin increased the radiosensitivity of colorectal tumours with P53 mutation both in vitro and in vivo.

CONCLUSION AND IMPLICATIONS

Metformin may be a radiotherapy adjuvant agent for colorectal cancers especially those carrying P53 mutation. Our findings provide a new strategy for further precise clinical trials for metformin on radiotherapy.

Pleiotropic effects of anti-diabetic drugs: A comprehensive review

Diabetes mellitus characterized by hyperglycaemia presents an array of comorbidities such as cardiovascular and renal failure, dyslipidemia, and cognitive impairments. Populations above the age of 60 are in an urgent need of effective therapies to deal with the complications associated with diabetes mellitus. Widely used anti-diabetic drugs have good safety profiles and multiple reports indicate their pleiotropic effects in diabetic patients or models. This review has been written with the objective of identifying the widely-marketed anti-diabetic drugs which can be efficiently repurposed for the treatment of other diseases or disorders. It is an updated, comprehensive review, describing the protective role of various classes of anti-diabetic drugs in mitigating the macro and micro vascular complications of diabetes mellitus, and differentiating these drugs on the basis of their mode of action. Notably, metformin, the anti-diabetic drug most commonly explored for cancer therapy, has also exhibited some antimicrobial effects. Unlike class specific effects, few instances of drug specific effects in managing cardiovascular complications have also been reported. A major drawback is that the pleiotropic effects of anti-diabetic drugs have been mostly investigated only in diabetic patients. Thus, for effective repurposing, more clinical trials devoted to analyse the effects of anti-diabetic drugs in patients irrespective of their diabetic condition, are required.

Effect of type 2 diabetes and antihyperglycemic drug therapy on signs of tumor invasion in papillary thyroid cancer

PURPOSE

This retrospective study investigated the association between worrisome pathological features of papillary thyroid cancer indicative of invasion and type 2 diabetes, as well as antihyperglycemic drug therapy for diabetes.

METHODS

The records of 14,167 patients who had undergone primary surgery for thyroid cancer were retrospectively reviewed and screened for concomitant diabetes. The diabetic and nondiabetic groups were age and gender matched, and further stratified by treatment, including five single antihyperglycemic drugs.

RESULTS

The study population comprised 942 patients, including 471 patients each with and without diabetes. The rate of worrisome pathological features was higher in diabetic patients than in nondiabetic patients (49.26% cf. 30.57%, P < 0.001), mainly reflected by extrathyroidal extension (34.82% cf. 5.94%, P < 0.001) and lymph node metastasis (42.68% cf. 33.55%, P < 0.001). The number of lymph node metastases in those treated with acarbose (0.32) was significantly lower compared with groups given any of the other four antihyperglycemic drugs (ranging from 1.51 to 2.15; P = 0.001 to 0.05).

CONCLUSIONS

Papillary thyroid cancer complicated with type 2 diabetes has a higher risk of invasive tumor growth. Compared with other antihyperglycemic drugs, patients with acarbose had the lowest risk of aggressive tumor growth. These results may evoke pathophysiological hypotheses to be explored in preclinical and clinical studies.

Is Type 2 Diabetes Causally Associated With Cancer Risk? Evidence From a Two-Sample Mendelian Randomization Study

We conducted a two-sample Mendelian randomization study to investigate the causal associations of type 2 diabetes mellitus (T2DM) with risk of overall cancer and 22 site-specific cancers. Summary-level data for cancer were extracted from the Breast Cancer Association Consortium and UK Biobank. Genetic predisposition to T2DM was associated with higher odds of pancreatic, kidney, uterine, and cervical cancer and lower odds of esophageal cancer and melanoma but not associated with 16 other site-specific cancers or overall cancer. The odds ratios (ORs) were 1.13 (95% CI 1.04, 1.22), 1.08 (1.00, 1.17), 1.08 (1.01, 1.15), 1.07 (1.01, 1.15), 0.89 (0.81, 0.98), and 0.93 (0.89, 0.97) for pancreatic, kidney, uterine, cervical, and esophageal cancer and melanoma, respectively. The association between T2DM and pancreatic cancer was also observed in a meta-analysis of this and a previous Mendelian randomization study (OR 1.08; 95% CI 1.02, 1.14; P = 0.009). There was limited evidence supporting causal associations between fasting glucose and cancer. Genetically predicted fasting insulin levels were positively associated with cancers of the uterus, kidney, pancreas, and lung. The current study found causal detrimental effects of T2DM on several cancers. We suggest reinforcing the cancer screening in T2DM patients to enable the early detection of cancer.

Metformin: (future) best friend of the radiation oncologist?

Several molecules are being investigated for their ability to enhance the anti-tumor effect of radiotherapy. The widely prescribed antidiabetic drug metformin has been suggested to possess anti-cancer activity; data indicate that metformin could also enhance radiation sensitivity. The purpose of this review is to summarize current knowledge on the specific effect of metformin in the field of RT, while also discussing the many unknowns that persist. Preclinical models point to multiple mechanisms involved in the radiosensitizing effects of metformin that are mainly linked to mitochondrial complex I inhibition and AMP-activated protein kinase. Transposition of results from bench to bedside will be discussed through the lens of the drug concentration, its potential limits in human settings, and possible alternatives. Clinical data suggest metformin improves progression-free and overall survival in patients for many different cancers treated with RT; nevertheless, the results are not always consistent. The main limitations of the reviewed literature are the retrospective nature of studies, and most of the time, a lack of information on MTF treatment duration and the administered dosages. Despite these limitations, the possible mechanisms of the role of metformin and its utility in enhancing radiotherapy treatments are analyzed. Ongoing clinical trials are also discussed.

Survival of Colorectal Cancer Patients With Diabetes Mellitus: A Meta-Analysis

OBJECTIVES

Diabetes mellitus (DM) is associated with an elevated risk of various cancers, including colorectal cancer (CRC). Similarly, pre-existing DM may also influence prognosis among patients with CRC. We performed a systematic review and meta-analysis to assess the association between DM and risk of death and relapse after a diagnosis of CRC.

METHODS

PubMed, Scopus, Web of Science, The Cochrane Library and Embase were searched from inception until July 2019 for studies reporting prognosis of patients with DM and CRC. The primary outcome of the study refers to overall mortality in patients with vs without diabetes. Secondary endpoints were cancer-specific mortality and progression or relapse-free survival. The risk of death and relapse are reported as hazard ratio (HR) with 95% confidence interval (CI), and an HR >1 was associated with worst outcome in patients with diabetes compared to those without diabetes.

RESULTS

Mortality and relapse associated with DM in patients with CRC were evaluated among 5,267,980 participants (total of 82 studies). Overall, concomitant diagnosis of CRC and DM were associated with an independent increased risk of overall mortality (HR, 1.21; 95% CI, 1.17 to 1.25; p<0.01) and CSM (HR, 1.11; 95% CI, 1.05 to 1.17; p<0.01). Patients were also at increased risk of relapse (HR, 1.09; 95% CI, 1.02 to 1.16; p<0.01).

CONCLUSIONS

In CRC patients with DM, diabetes decreased survival and increased the risk of relapse. Adequate control of lifestyle choices, more intensive follow ups, use of some oral antidiabetics, dietary restrictions, physical activity and monitoring of diabetes-associated complications are measures for reducing mortality in this setting.