Metformin prevents hormonal and metabolic disturbances and 1,2-dimethylhydrazine-induced colon carcinogenesis in non-diabetic rats

Metformin's role in lowering colorectal cancer risk among individuals with diabetes from the Southern Community Cohort Study

BACKGROUND

Metformin, utilized to manage hyperglycemia, has been linked to a reduced risk of colorectal cancer (CRC) among individuals with diabetes. However, evidence is lacking for non-Hispanic Black individuals and those with lower socioeconomic status (SES), who face elevated risk for both diabetes and CRC. In this study, we investigated the association between metformin use and incident CRC risk within the Southern Community Cohort Study (SCCS), a racially- and SES-diverse prospective cohort.

METHODS

Participants reported their diabetes diagnosis and medications, including metformin, upon enrollment (2002-2009) and during follow-up surveys approximately every five years. Incident cases of CRC were identified through state cancer registries and the National Death Index. Proportional hazards models were employed to explore the relationship between metformin use and CRC risk, adjusted for cancer risk factors.

RESULTS

A total of 25,992 participants with diabetes were included in the analysis, among whom 10,095 were taking metformin. Of these participants, 76% identified as non-Hispanic Black, and 60% reported household incomes <$15,000/year. Metformin use was associated with a significantly lower CRC risk (HR [95% CI]: 0.71 [0.55-0.93]), with consistent results for both colon (0.80 [0.59-1.07]) and rectal cancers (0.49 [0.28-0.86]). The protective association appeared to be stronger among non-Hispanic White individuals (0.51 [0.31-0.85]) compared to non-Hispanic Black participants (0.80 [0.59-1.08], p-interaction =.13). Additionally, a protective association was observed among obese individuals (BMI ≥30 kg/m2, 0.59 [0.43-0.82] but not among non-obese participants (0.99 [0.65-1.51], p-interaction =.05) CONCLUSION: Our findings indicate that metformin use is associated with a reduced risk of CRC in individuals with diabetes, including among those from predominantly low SES backgrounds. These results support previous epidemiological findings, and demonstrate that the protective association for metformin in relation to incident CRC likely generalizes to populations with higher underlying risk.

Repurposing drugs for solid tumor treatment: focus on immune checkpoint inhibitors

Cancer remains a significant global health challenge with limited treatment options beyond systemic therapies, such as chemotherapy, radiotherapy, and molecular targeted therapy. Immunotherapy has emerged as a promising therapeutic modality but the efficacy has plateaued, which therefore provides limited benefits to patients with cancer. Identification of more effective approaches to improve patient outcomes and extend survival are urgently needed. Drug repurposing has emerged as an attractive strategy for drug development and has recently garnered considerable interest. This review comprehensively analyses the efficacy of various repurposed drugs, such as transforming growth factor-beta (TGF-β) inhibitors, metformin, receptor activator of nuclear factor-κB ligand (RANKL) inhibitors, granulocyte macrophage colony-stimulating factor (GM-CSF), thymosin α1 (Tα1), aspirin, and bisphosphonate, in tumorigenesis with a specific focus on their impact on tumor immunology and immunotherapy. Additionally, we present a concise overview of the current preclinical and clinical studies investigating the potential therapeutic synergies achieved by combining these agents with immune checkpoint inhibitors.

Selective Role of TNFα and IL10 in Regulation of Barrier Properties of the Colon in DMH-Induced Tumor and Healthy Rats

Recently it has been reported that the tumor adjacent colon tissues of 1,2-dymethylhydrazine induced (DMH)-rats revealed a high paracellular permeability. We hypothesized that the changes might be induced by cytokines. Colorectal cancer is accompanied by an increase in tumor necrosis factor alpha (TNFα) and interleukin 10 (IL10) that exert opposite regulatory effects on barrier properties of the colon, which is characterized by morphological and functional segmental heterogeneity. The aim of this study was to analyze the level of TNFα and IL10 in the colon segments of DMH-rats and to investigate their effects on barrier properties of the proximal and distal parts of the colon in healthy rats. Enzyme immunoassay analysis showed decreased TNFα in tumors in the distal part of the colon and increased IL10 in proximal tumors and in non-tumor tissues. Four-hour intraluminal exposure of the colon of healthy rats with cytokines showed reduced colon barrier function dependent on the cytokine: TNFα decreased it mainly in the distal part of the colon, whereas IL10 decreased it only in the proximal part. Western blot analysis revealed a more pronounced influence of IL10 on tight junction (TJ) proteins expression by down-regulation of the TJ proteins claudin-1, -2 and -4, and up-regulation of occludin only in the proximal part of the colon. These data may indicate a selective role of the cytokines in regulation of the barrier properties of the colon and a prominent role of IL10 in carcinogenesis in its proximal part.

Assessment of antitumor activity of BP-C1, a platinum-based anticancer agent with a lignin-derived polymeric ligand, in autochthonous induced and spontaneous carcinogenesis rodent models

BACKGROUND

A standard approach to study the anticancer activity of novel drugs is their testing in animals with inoculated tumors, which has some limitations. An alternative is the use of spontaneous or carcinogen-induced tumor models as they have better translation potential. The carcinogen-induced and transgenic tumor models were used to assess the antitumor activity of BP-C1, a platinum-containing drug with lignin-derived polymeric ligand.

METHODS

We used female Swiss-H-derived mice and Wistar female rats to induce autochthonous tumors via exposure to benzo[a]pyrene and 1,2-dimethylhydrazine, respectively. Additionally, transgenic HER-2/neu FVB/N female mice, prone to the development of spontaneous mammary carcinomas, were used.

RESULTS

Antitumor activity of BP-C1 was observed in soft tissue sarcomas, induced by benzo[a]pyrene. The animals treated with BP-C1 exhibited more stabilizations and therapy responses compared to placebo controls. The efficacy of BP-C1 was somewhat reduced compared to cyclophosphamide; however, their combination resulted in an enhanced antitumor effect. For the 1,2-dimethylhydrazine-induced rat colon cancer model, BP-C1 reduced tumor multiplicity by 21-41 %. For mammary adenocarcinomas in HER-2/neu FVB/N mice, short-termed complete responses were observed in the BP-C1 groups with a frequency of 12-13 %, while complete responses were absent in the placebo group.

CONCLUSION

The results acquired indicated a wide spectrum of antitumor activity of BP-C1.

Metformin exerts an antitumoral effect on papillary thyroid cancer cells through altered cell energy metabolism and sensitized by BACH1 depletion

PURPOSE

Aberrant cell energy metabolism is one of the features of thyroid carcinogenesis. Metformin may reduce the risk of cancer, and BACH1 was reported to affect the sensitivity of cancer cells to metformin. The aims of this study were to investigate whether metformin exerts antitumor effects in PTC cells and explore the role of BACH1 depletion on the sensitivity of PTC cells to metformin.

METHODS

The viability and proliferation of PTC cell lines were analyzed with MTT and colony forming assay. Energy utilization and mitochondrial respiration were measured using Seahorse XF instruments and Mitochondrial complex-1 activity assay.

RESULTS

Our results showed the anti-proliferative and pro-apoptotic effects of metformin in PTC cells. Furthermore, metformin changed the pattern of cell energy metabolism in PTC cells, which manifested as inhibition of mitochondrial respiration, and the combination of BACH1 depletion with metformin magnified the effect of metformin alone.

CONCLUSIONS

In conclusion, metformin exerts an antitumoral effect on PTC cells both in vitro and in xenograft mouse models. A possible mechanism is through inhibiting glucose metabolism and mitochondrial respiration process. Knocking down BACH1 caused the switching of energy metabolism and sensitized PTC cells to metformin, which eventually enhanced the anti-tumor effect of metformin.

Drug Repurposing Strategies for Non-Cancer to Cancer Therapeutics

Global efforts invested for the prevention and treatment of cancer need to be repositioned to develop safe, effective, and economic anticancer therapeutics by adopting rational approaches of drug discovery. Drug repurposing is one of the established approaches to reposition old, clinically approved off patent noncancer drugs with known targets into newer indications. The literature review suggests key role of drug repurposing in the development of drugs intended for cancer as well as noncancer therapeutics. A wide category of noncancer drugs namely, drugs acting on CNS, anthelmintics, cardiovascular drugs, antimalarial drugs, anti-inflammatory drugs have come out with interesting outcomes during preclinical and clinical phases. In the present article a comprehensive overview of the current scenario of drug repurposing for the treatment of cancer has been focused. The details of some successful studies along with examples have been included followed by associated challenges.

The Antitumor Activity of Ginger against Colorectal Cancer Induced by Dimethylhydrazine in Rats

BACKGROUND

Bowl or colorectal cancer (CRC) is the third most common type of cancer with about two million new cases every year. CRC is the second leading cause of cancer related mortalities.

OBJECTIVE

The study aims to evaluate the anticancer activity of ethanolic Ginger Extract (GE) in HCT-116 colon cells and colorectal tumors induced by dimethylhydrazine (DMH).

METHODS

The antiproliferative activity was measured by MTT assay and the gene expression was assessed by q-RTPCR. For the antitumor study, rats were divided into five groups in random; control, group two was orally treated with 300 mg/kg of GE for 21 weeks, group three was s.c. injected with DMH (20 mg/kg) for 9 weeks, and groups four and five were treated with DMH and then treated with cisplatin (2.5 mg/kg, i.p) or GE, respectively, for 21 weeks.

RESULTS

GE had a significant antiproliferative activity with IC50~ 12.5 µg/ml. GE induced both extrinsic and intrinsic apoptotic pathways. GE induced the expression of FasL, TRAIL, p53, and caspase-8 and downregulated Bcl-2 and survivin genes. Treatment of rats with DMH resulted in 100% tumor incidence and 2.3 tumors/rat. DMH significantly elevated the serum ALT, urea, and creatinine and significantly decreased the body weight gain. DMH also caused significant reductions in the hepatic GSH level, and the activities of catalase, SOD, GST, and GR in the liver as well as the renal GSH content and γ-GT activity. The colon from rats insulted with DMH showed adenomatous polyps with polymorphism and mitosis. The mucosa and submucosa were infested with inflammatory cells while serosa and muscularis were devoid from these cells. However, the muscularis was infiltrated with cystic formation, anaplastic changes, and hemorrhage. GE was able to alleviate all the previous deleterious effects of DMH and it was superior to cisplatin in its ameliorative effects. It did so without eliciting hepatotoxicity or nephrotoxicity which were shown in the group treated with DMH and cisplatin.

CONCLUSION

This study proved that the antitumor activity of GE against the DMH induced-CRC is superior to cisplatin. GE was also safer than cisplatin and did not elicit hepatotoxicity or nephrotoxicity. GE induced apoptosis and has carcinostatic activity.

The ANXA2/S100A10 Complex—Regulation of the Oncogenic Plasminogen Receptor

The generation of the serine protease plasmin is initiated by the binding of its zymogenic precursor, plasminogen, to cell surface receptors. The proteolytic activity of plasmin, generated at the cell surface, plays a crucial role in several physiological processes, including fibrinolysis, angiogenesis, wound healing, and the invasion of cells through both the basement membrane and extracellular matrix. The seminal observation by Albert Fischer that cancer cells, but not normal cells in culture, produce large amounts of plasmin formed the basis of current-day observations that plasmin generation can be hijacked by cancer cells to allow tumor development, progression, and metastasis. Thus, the cell surface plasminogen-binding receptor proteins are critical to generating plasmin proteolytic activity at the cell surface. This review focuses on one of the twelve well-described plasminogen receptors, S100A10, which, when in complex with its regulatory partner, annexin A2 (ANXA2), forms the ANXA2/S100A10 heterotetrameric complex referred to as AIIt. We present the theme that AIIt is the quintessential cellular plasminogen receptor since it regulates the formation and the destruction of plasmin. We also introduce the term oncogenic plasminogen receptor to define those plasminogen receptors directly activated during cancer progression. We then discuss the research establishing AIIt as an oncogenic plasminogen receptor-regulated during EMT and activated by oncogenes such as SRC, RAS, HIF1α, and PML-RAR and epigenetically by DNA methylation. We further discuss the evidence derived from animal models supporting the role of S100A10 in tumor progression and oncogenesis. Lastly, we describe the potential of S100A10 as a biomarker for cancer diagnosis and prognosis.

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.

The Antitumor Activity of a Novel Fluorobenzamidine against Dimethylhydrazine- Induced Colorectal Cancer in Rats

BACKGROUND

Colorectal cancer is among the leading causes of death worldwide. The incidence of deaths is expected to be 11.4 million in 2030.

OBJECTIVE

We aimed to evaluate the in vitro and in vivo antioxidant and antitumor activities of a novel Bithiophene- Fluorobenzamidine (BFB) against DMH-induced colorectal cancer in rats.

METHODS

The antiproliferative activity of BFB against HCT-116 colon cancer cells and apoptotic genes was assessed. In vivo study was also conducted in which 80 adult male rats were divided into 5 groups; control, BFB, and the other 3 groups were injected with DMH (20mg/kg, s.c., for 9 weeks). Group 4 was injected with 5 doses of cisplatin (2.5mg/kg, i.p over 21 weeks) and group 5 was injected with 3 doses/week of BFB (2.5mg/kg, i.p, for 21 weeks).

RESULTS

BFB exhibited weak to moderate in vitro antioxidant activity. It had a strong antiproliferative activity with IC50 ~0.3µg/ml. BFB induced extrinsic apoptosis through the upregulation of FasL, TRAL, p53 and caspase-8, and intrinsic apoptosis through the downregulation of Bcl-2 and survivin. BFB decreased the tumor incidence, multiplicity and size and improved the decreased body weight. BFB also ameliorated the functions of kidney and liver and antioxidants deteriorated by DMH. BFB significantly improved the pathological changes caused by DMH in colon tissues.

CONCLUSION

BFB showed a very promising antitumor activity against colorectal cancer induced by DMH in rats without causing hepato- or nephrotoxicity.

Drug repurposing in oncology: Compounds, pathways, phenotypes and computational approaches for colorectal cancer

The strategy of using existing drugs originally developed for one disease to treat other indications has found success across medical fields. Such drug repurposing promises faster access of drugs to patients while reducing costs in the long and difficult process of drug development. However, the number of existing drugs and diseases, together with the heterogeneity of patients and diseases, notably including cancers, can make repurposing time consuming and inefficient. The key question we address is how to efficiently repurpose an existing drug to treat a given indication. As drug efficacy remains the main bottleneck for overall success, we discuss the need for machine-learning computational methods in combination with specific phenotypic studies along with mechanistic studies, chemical genetics and omics assays to successfully predict disease-drug pairs. Such a pipeline could be particularly important to cancer patients who face heterogeneous, recurrent and metastatic disease and need fast and personalized treatments. Here we focus on drug repurposing for colorectal cancer and describe selected therapeutics already repositioned for its prevention and/or treatment as well as potential candidates. We consider this review as a selective compilation of approaches and methodologies, and argue how, taken together, they could bring drug repurposing to the next level.

iTRAQ-based proteomic analysis of DMH-induced colorectal cancer in mice reveals the expressions of β-catenin, decorin, septin-7, and S100A10 expression in 53 cases of human hereditary polyposis colorectal cancer

PURPOSE

The aim of this study is to explore the roles of β-catenin, decorin, septin-7, and S100A10 expression in colorectal cancer development.

METHODS

Twenty-five BALB/c mice were divided into five groups; four groups were administrated N,N-dimethylhydrazine for 0, 10, 15, and 20 weeks, and one group was administrated normal saline for 20 weeks. The colons were collected for histopathological analysis. Protein samples prepared from the frozen colon tissues of mice treated with N,N-dimethylhydrazine for the different time points were evaluated using the isobaric tags for relative and absolute quantification (iTRAQ) labeling technique coupled with the 2D liquid chromatography-tandem mass spectrometry analysis. Based on the proteomic analysis results, immunohistochemical staining of β-catenin, decorin, septin-7, and S100A10 was performed in paraffin-embedded mice colorectal tissue, and 53 cases of human hereditary polyposis colorectal cancer samples.

RESULTS

Colorectal cancer was observed in mice treated with N,N-dimethylhydrazine for 20 weeks, and adenomas were observed in mice subjected to the 10-, and 15-week treatments. Seventy-two differentially expressed proteins were involved in the development of cancer as per the iTRAQ and spectrometry analysis. In normal epithelium, adenoma, and cancer from human hereditary polyposis colorectal cancer, S100A10 expression (c2 = 100.989, P = 0.000) was highest in cancer, whereas decorin (c2 = 12.852, P = 0.002) and septin-7 (c2 = 66.519, P = 0.002) expressions were highest in the normal epithelium, which was confirmed via immunohistochemical staining.

CONCLUSIONS

The subcellular localization of β-catenin and decorin, septin-7, and S100A10 expressions are associated with the development of colorectal cancer in mice after N,N-dimethylhydrazine treatment and in human hereditary polyposis colorectal cancers.

Increased paracellular permeability of tumor-adjacent areas in 1,2-dimethylhydrazine-induced colon carcinogenesis in rats

Objective:

The morphology and functions of the proximal and distal large intestine are not the same. The incidence of colorectal cancer in these regions is also different, as tumors more often appear in the descending colon than in the ascending colon. Inflammatory bowel disease and colorectal cancer can increase transepithelial permeability, which is a sign of reduced intestinal barrier function. However, there is not enough evidence to establish a connection between the difference in colorectal cancer incidence in the proximal and distal colon and intestinal permeability or the effects of carcinogenesis on the barrier properties in various areas of the colon. The aim of the study was to assess the permeability of different segments of the large intestine according to a developed mapping methodology in healthy rats and rats with 1,2-dimethylhydrazine (DMH)-induced colon adenocarcinoma.

Methods:

The short circuit current, the transepithelial electrical resistance and the paracellular permeability to fluorescein of large intestine wall of male Wistar rats were examined in the Ussing chambers. The optical density of the solution from the serosa side to assess the concentration of the diffused fluorescein from mucosa to serosa was analyzed by spectrophotometry. The morphometric and histological studies were performed by optical microscopy.

Results:

Rats with DMH-induced colon adenocarcinomas showed elevated transepithelial electrical resistance in the areas of neoplasm development. In contrast, there was no change in the electrophysiological properties of tumor adjacent areas, however, the paracellular permeability of these areas to fluorescein was increased compared to the control rats and was characterized by sharply reduced barrier function.

Conclusions:

The barrier properties of the colon vary depending on tumor location. The tumors were less permeable than the intact intestinal wall and probably have a negative influence on tumor-adjacent tissues by disrupting their barrier function.

Metformin and Colorectal Cancer

Colorectal Cancer (CRC) is one of the most frequently encountered neoplasms in humans. The incidence of CRC has been increasing and new strategies for prevention, including chemoprevention, are required to lower its incidence and associated mortality. Metformin is a biguanide compound commonly used for the treatment of diabetes mellitus. Many recent basic research, epidemiological and clinical trial studies have indicated that metformin has benefits not only in diabetes treatment, but also in lowering the risk of developing cancer (including CRC). These studies indicate that metformin may be a candidate chemoprevention agent for CRC. This review article shall discuss the present evidence of metformin treatment and CRC, as well as outline our challenge in the investigation of metformin use in chemoprevention therapy for colorectal tumors.