Greater development of 1,2-dimethylhydrazine-induced colon cancer in a rat model of type 2 diabetes mellitus

Bioinformatical analysis and experimental validation of endoplasmic reticulum stress-related biomarker genes in type 2 diabetes mellitus

Introduction

Endoplasmic reticulum stress (ERS) is a prominent etiological factor in the pathogenesis of diabetes. Nevertheless, the mechanisms through which ERS contributes to the development of diabetes remain elusive.

Methods

Transcriptional expression profiles from the Gene Expression Omnibus (GEO) datasets were analyzed and compared to obtain the differentially expressed genes (DEGs) in T2DM. Following the intersection with ERS associated genes, the ERS related T2DM DEGs were identified. Receiver operating characteristic (ROC) and Least Absolute Shrinkage and Selection Operator (LASSO) analysis were performed to screen out the ERS related biomarker genes and validate their diagnostic values. Gene expression level was detected by qPCR and Elisa assays in diabetic mice and patient serum samples.

Results

By analyzing the transcriptional expression profiles of the GEO datasets, 49 T2DM-related DEGs were screened out in diabetic islets. RTN1, CLGN, PCSK1, IAPP, ILF2, IMPA1, CCDC47, and PTGES3 were identified as ERS-related DEGs in T2DM, which were revealed to be involved in protein folding, membrane composition, and metabolism regulation. ROC and LASSO analysis further screened out CLGN, ILF2, and IMPA1 as biomarker genes with high value and reliability for diagnostic purposes. These three genes were then demonstrated to be targeted by the transcription factors and miRNAs, including CEBPA, CEBPB, miR-197-5p, miR-6133, and others. Among these miRNAs, the expression of miR-197-5p, miR-320c, miR-1296-3P and miR-6133 was down-regulated, while that of miR-4462, miR-4476-5P and miR-7851-3P was up-regulated in diabetic samples. Small molecular drugs, including D002994, D001564, and others, were predicted to target these genes potentially. qPCR and Elisa analysis both validated the same expression alteration trend of the ERS-related biomarker genes in diabetic mice and T2DM patients.

Discussion

These findings will offer innovative perspectives for clinical diagnosis and treatment strategies for T2DM.

Hyperglycemia Promotes Liver Metastasis of Colorectal Cancer via Upregulation of Integrin αvβ6

Background

Diabetes is related to higher risk of multiple cancers. This study aimed to explore the effect and mechanism of diabetes on liver metastasis of CRC.

Material/Methods

Overall and liver metastasis-free survival in diabetic and non-diabetic CRC patients were compared by Kaplan-Meier analysis. Expression of αvβ6 was detected by immunohistochemistry in clinical specimens. Effects of hyperglycemia on αvβ6 expression in colon cancer cells were assessed by western blot, real-time PCR, and flowcytometry. Effects of hyperglycemia on migration and invasion were demonstrated by Transwell assay. Expression and activity of MMP-9 and MMP-2 were determined by real-time PCR and gelatin zymography. Liver metastatic nodules were counted and β6 expression was detected by western blot in a liver metastasis mouse model.

Results

CRC patients with diabetes had poorer overall and liver metastasis-free survival, and diabetes was associated with higher αvβ6 expression in CRC specimens. Hyperglycemia promoted the invasion and migration of colon cancer cells, and upregulated the expression and activity of MMP-9, which were attenuated by inhibition of αvβ6. Hyperglycemia upregulated the expression of β6 and cell surface expression of αvβ6, which was reduced by ERK inhibitor. The in vitro results were confirmed in vivo in the mouse model.

Conclusions

Our study demonstrated the enhancing effect of hyperglycemia on liver metastasis of CRC, and showed that αvβ6 was involved in this process, suggesting that control of glucose levels and inhibition of αvβ6 can reduce the risk of liver metastasis in diabetic CRC patients.

Mammalian models of chemically induced primary malignancies exploitable for imaging-based preclinical theragnostic research

Compared with transplanted tumor models or genetically engineered cancer models, chemically induced primary malignancies in experimental animals can mimic the clinical cancer progress from the early stage on. Cancer caused by chemical carcinogens generally develops through three phases namely initiation, promotion and progression. Based on different mechanisms, chemical carcinogens can be divided into genotoxic and non-genotoxic ones, or complete and incomplete ones, usually with an organ-specific property. Chemical carcinogens can be classified upon their origins such as environmental pollutants, cooked meat derived carcinogens, N-nitroso compounds, food additives, antineoplastic agents, naturally occurring substances and synthetic carcinogens, etc. Carcinogen-induced models of primary cancers can be used to evaluate the diagnostic/therapeutic effects of candidate drugs, investigate the biological influential factors, explore preventive measures for carcinogenicity, and better understand molecular mechanisms involved in tumor initiation, promotion and progression. Among commonly adopted cancer models, chemically induced primary malignancies in mammals have several advantages including the easy procedures, fruitful tumor generation and high analogy to clinical human primary cancers. However, in addition to the time-consuming process, the major drawback of chemical carcinogenesis for translational research is the difficulty in noninvasive tumor burden assessment in small animals. Like human cancers, tumors occur unpredictably also among animals in terms of timing, location and the number of lesions. Thanks to the availability of magnetic resonance imaging (MRI) with various advantages such as ionizing-free scanning, superb soft tissue contrast, multi-parametric information, and utility of diverse contrast agents, now a workable solution to this bottleneck problem is to apply MRI for noninvasive detection, diagnosis and therapeutic monitoring on those otherwise uncontrollable animal models with primary cancers. Moreover, it is foreseeable that the combined use of chemically induced primary cancer models and molecular imaging techniques may help to develop new anticancer diagnostics and therapeutics.

The peroxisome proliferator-activated receptor (PPAR) α agonist fenofibrate suppresses chemically induced lung alveolar proliferative lesions in male obese hyperlipidemic mice

Activation of peroxisome proliferator-activated receptor (PPAR) α disrupts growth-related activities in a variety of human cancers. This study was designed to determine whether fenofibrate, a PPARα agonist, can suppress 4-nitroquinoline 1-oxide (4-NQO)-induced proliferative lesions in the lung of obese hyperlipidemic mice. Male Tsumura Suzuki Obese Diabetic mice were subcutaneously injected with 4-NQO to induce lung proliferative lesions, including adenocarcinomas. They were then fed a diet containing 0.01% or 0.05% fenofibrate for 29 weeks, starting 1 week after 4-NQO administration. At week 30, the incidence and multiplicity (number of lesions/mouse) of pulmonary proliferative lesions were lower in mice treated with 4-NQO and both doses of fenofibrate compared with those in mice treated with 4-NQO alone. The incidence and multiplicity of lesions were significantly lower in mice treated with 4-NQO and 0.05% fenofibrate compared with those in mice treated with 4-NQO alone (p<0.05). Both doses of fenofibrate significantly reduced the proliferative activity of the lesions in 4-NQO-treated mice (p<0.05). Fenofibrate also significantly reduced the serum insulin and insulin-like growth factor (IGF)-1 levels, and decreased the immunohistochemical expression of IGF-1 receptor (IGF-1R), phosphorylated Akt, and phosphorylated Erk1/2 in lung adenocarcinomas. Our results indicate that fenofibrate can prevent the development of 4-NQO-induced proliferative lesions in the lung by modulating the insulin-IGF axis.

Enhanced Urinary Bladder, Liver and Colon Carcinogenesis in Zucker Diabetic Fatty Rats in a Multiorgan Carcinogenesis Bioassay: Evidence for Mechanisms Involving Activation of PI3K Signaling and Impairment of p53 on Urinary Bladder Carcinogenesis

In the present study, modifying effects of diabetes on carcinogenesis induced in type 2 diabetes mellitus model Zucker diabetic fatty (ZDF) rats were investigated using a multiorgan carcinogenesis bioassay. Our re sults demonstrated enhancement of urinary bladder, colon and liver carcinogenesis in ZDF rats treated with five types of carcinogens (DMBDD). Elevated insulin and leptin and decreased adiponectin levels in the serum may be responsible for the high susceptibility of type 2 diabetes mellitus model rats to carcinogenesis in these organs. Possible mechanisms of increased susceptibility of diabetic rats to bladder carcinogenesis could be activation of the PI3K pathway and suppression of p53 in the urothelium in consequence of the above serum protein alterations.

Prevention of proliferative changes of forestomach mucosa by blood glucose control with insulin in alloxan-induced diabetic rats

Diabetes mellitus is one of the risk factors for carcinogenesis. Recently we reported that alloxan induces squamous cell carcinoma (SCC) with coincidental inflammation, bacteria/fungal infections, and a severe diabetic condition. The present study was conducted to examine the effects of blood glucose control with insulin on the proliferative changes of the forestomach in alloxan-induced diabetic rats. Male 15-week-old WBN/Kob rats were divided into a control group of non-treated rats with naturally occurring diabetes after 40 weeks of age (non-treated group), alloxan-induced diabetic rats (AL group), and alloxan-induced diabetic rats given insulin implant treatment (AL + In group). The animals were sacrificed at 90 weeks of age for histopathologic examination. The blood glucose and urinary glucose level of the AL + In group fluctuated variously from high to normal levels compared with a constantly high level of AL (for 75 weeks) as well as in the non-treated group (for 50 weeks). The mucosal hyperplasia in the forestomach developed in 88.2% of the AL group and 37.5% of the non-treated group, but in only 10.0% of the AL + In group. SCC was only detected in 23.5% of the AL group. Hyperplastic changes were constantly accompanied by inflammation and fungal/bacterial infections in the AL and non-treated groups, whereas inflammation and fungal infection were completely suppressed in the AL + In group. These findings demonstrate that blood glucose control suppressed neoplastic changes in alloxan-induced diabetic rats. We postulate that inflammation together with bacterial/fungal infections under prolonged severe diabetic conditions play a pivotal role in carcinogenesis.