Insulin resistance, apoptosis, and colorectal adenoma risk

Correlation Between Skeletal Muscle Mass and Different Pathological Types of Colorectal Polyp in Chinese Asymptomatic Population

Background

Low relative muscle mass was identified to be related to ascending risk of pre-cancerous polyps (adenoma) in recent cohort study. Our study aimed to dig out the correlation between muscle mass and different pathological types of colorectal polyps in Chinese asymptomatic population.

Methods

In all, 5923 adults were included. The effects of low skeletal muscle mass index (SMI) on colorectal polyp occurrence, including different pathological types, and the effects modification of age and BMI were analyzed using univariate and multivariate logistic regression.

Results

Lower SMI was connected with the lower occurrence of colorectal polyp (OR: 0.810, 95% CI: 0.683~0.960, p=0.015). Considering different pathological types of colorectal polyps, lower SMI was associated with lower occurrence of inflammatory polyp (OR: 0.633, 95% CI: 0.434~0.898, p=0.013), rather than conventional adenoma and serrated polyp (all p>0.05). Besides, SMI was positively related to the occurrence of 2 pathological types of colorectal polyp in males: inflammatory polyp (OR: 1.237, 95% CI: 1.058~1.444, p=0.007) and serrated polyp (OR: 1.288, 95% CI: 1.143~1.456, p<0.001). The interaction effect of BMI and SMI on occurrence of inflammatory polyp after adjusting age and smoking status was significant (p=0.015). For individuals with low SMI (compared with the normal SMI group), the incidence of inflammatory polyp was reduced from 8.95% to 3.50% in the low BMI quartile (Q1) in the adjusted model (OR of 0.332, 95% CI: 0.005-0.061, p<0.001). It was noticeable for males rather than females that individuals with colorectal polyps had higher levels of SMI (p=0.003). In addition, individuals with inflammatory polyps as well as serrated polyps possessed higher levels of SMI in males (all p<0.05).

Conclusion

Generally, especially in Chinese asymptomatic males, low SMI kept independent effect on the presence of inflammatory polyp and serrated polyp, rather than conventional adenoma.

Triglyceride-glucose index (TyG index) is associated with a higher risk of colorectal adenoma and multiple adenomas in asymptomatic subjects

HYPOTHESIS

The objective of this study is to evaluate the predictive ability of the TyG index for the presence of adenoma and multiple adenomas in an asymptomatic population.

DESIGN

A secondary analysis was conducted on a prospective cohort of asymptomatic subjects aged between 50 and 75 who underwent CRC screening. Fasting blood glucose (FBG) and lipid profiles were measured within three months prior colonoscopy. TyG index was estimated as ln [fasting triglycerides (mg/dL) × FBG (mg/dL)/2]. Multivariate logistic regression was performed to assess the association between the TyG index and the risk of adenoma. Its association with multiple adenomas (≥5) and the continuous number of adenomas were assessed by multinomial regression and log-normal linear regression, respectively.

RESULTS

A total of 1,538 subjects were recruited among which 876 subjects (57%) had at least one adenoma detected. Elevated TyG index was positively associated with the incidence of adenoma (adjusted odds ratio [aOR]: 1.26, 95% confidence interval [CI]: 1.04-1.54). Compared with the lowest TyG index (≤ 8) group, the risk of adenoma was the highest among subjects in the highest TyG index (> 10) group (aOR: 3.36, 95% CI: 1.44-7.73). As compared to the non-adenoma group, the TyG index was also positively associated with multiple adenomas (aOR: 1.74, 95% CI: 1.17-2.57), and the estimate was also the highest in the highest TyG group (aOR: 14.49, 95% CI: 3.12-67.20). As for the number of adenomas, the positive association was maintained (Estimates: 1.06, 95% CI: 1.01-1.12) while the number of adenomas increase the most in the highest TyG index group (Estimates: 1.35, 95% CI: 1.10-1.65).

CONCLUSIONS

Elevated TyG index is associated with an increased risk of colorectal adenoma and an increased number of adenomas for asymptomatic subjects aged ≥50.

TRIAL REGISTRATION

This study was registered on clinicaltrials.gov (NCT03597204 and NCT04034953).

Expediting the development of robust 5-FU-resistant colorectal cancer models using innovative combined in vivo and in vitro strategies

BACKGROUND

5-Fluorouracil (5-FU) is a cornerstone in colorectal cancer therapy, but resistance has compromised its efficacy, necessitating detailed research into resistance mechanisms. Traditional methods for developing 5-FU-resistant cell lines are lengthy, unstable, and often unrepresentative of clinical scenarios.

METHODS

We devised a rapid approach to create 5-FU-resistant colorectal cancer cells using an integrated in vivo/in vitro methodology. HCT116 cells were pretreated with 5-FU, then implanted into nude mice. Tumor growth was monitored, and cells from the tumors were cultured to establish the HCT116-Tumor cell line. Cells from 5-FU-exposed tumors received increasing 5-FU doses to induce resistance, creating the tumor-derived resistant (TR) cell line. Cells cultured without 5-FU were termed tumor-derived parental (TP) cells. An in vitro 5-FU resistance model, CR, served as a benchmark. Resistance metrics were evaluated using CCK-8 assays, Western Blotting, flow cytometry, and in vivo studies. Proteomics identified resistance-related differentially expressed proteins (DEPs).

RESULTS

Low-dose 5-FU pretreatment accelerated tumor growth. Combining in vivo and in vitro methods, we developed 5-FU-resistant TR cells within two and a half months, faster than the ten-month conventional protocol. TR cells showed stronger and more durable 5-FU resistance than CR cells, with inhibited apoptosis, autophagy, and ferroptosis, and activation of MDR1. Proteomic analysis indicated more DEPs in TR cells, suggesting unique resistance mechanisms. Animal studies confirmed enhanced drug resistance in TR cells.

CONCLUSIONS

Our integrated approach rapidly develops colorectal cancer cells with robust 5-FU resistance, offering a potent model for exploring multiple resistance pathways and counter-resistance strategies.

Exploring Vitamin D Deficiency and IGF Axis Dynamics in Colorectal Adenomas

(1) Colorectal cancer is a major cause of cancer-related death, with colorectal adenomas (CRAs) serving as precursors. Identifying risk factors such as vitamin D deficiency and the insulin-like growth factor (IGF) axis is crucial for prevention. (2) This case-control study included 85 participants (53 CRA patients and 32 controls) who underwent colonoscopy. We measured serum vitamin D3 (cholecalciferol), calcidiol (vitamin D metabolite), calcitriol (active vitamin D metabolite), insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein-3 (IGFBP-3) to explore their associations with CRA risk. (3) Results: We found that lower cholecalciferol levels were a significant risk factor for CRA (OR = 4.63, p = 0.004). Although no significant differences in calcidiol and calcitriol levels were observed between CRA patients and controls, calcidiol deficiency was common in the study population. IGF-1 levels inversely correlated with age, calcitriol, and IGFBP-3 in CRA patients. (4) This study highlights the potential of lower cholecalciferol levels to detect patients at risk of CRA when calcidiol values cannot, suggesting the importance of evaluating different vitamin D metabolites in cancer prevention research. Our findings underscore the need to further investigate the interactions between calcitriol, the active form of vitamin D, and the IGF axis in colorectal cancer development.

Investigating the Effects of AL049796.1 Silencing in Inhibiting High Glucose-Induced Colorectal Cancer Progression

Patients with colorectal cancer (CRC) and diabetes share many risk factors. Despite a strong association between diabetes and CRC being widely studied and confirmed, further genetic research is needed. This study found higher AL049796.1 and TEA domain transcription factor 1 (TEAD1) levels (both mRNA and protein) in CRC tissues of diabetic patients compared with nondiabetics, but no significant difference in miR-200b-3p levels. A positive correlation between AL049796.1 and TEAD1 protein existed regardless of diabetes status, whereas miR-200b-3p was only negatively correlated with TEAD1 protein in nondiabetic CRC tissues. In vitro experiments have shown that high glucose (HG) treatment increased AL049796.1 in CRC cells, and AL049796.1 silencing reduced HG-induced proliferation, migration and invasion, as well as connective tissue growth factor, cysteine-rich angiogenic inducer 61, and epidermal growth factor receptor protein expression. Mechanistic investigations indicated that AL049796.1 could mitigate suppression of miR-200b-3p on TEAD1 posttranscriptionally by acting as a competitive binder. In vivo, subcutaneous CRC tumors in streptozotocin (STZ)-induced mice grew significantly faster; AL049796.1 silencing did not affect the growth of subcutaneous CRC tumors but significantly reduced that of STZ-induced mice. Our study suggests that AL049796.1 independently contributes to the risk of CRC in diabetic patients, highlighting its potential as both a therapeutic target and a novel biomarker for CRC among individuals with diabetes.

The Relationship Between Serum Lipids and the Formation of Colorectal Polyps

BACKGROUND AND AIMS

Obesity, metabolic syndrome, and hyperlipidemia are known as risk factors for colorectal tumors. Colorectal polyps are accepted as potential precursors of colorectal cancer (CRC). This study was designed to clarify the association between the levels of serum lipids and the presence of colorectal polyps.

METHODS

This study was conducted at Basaksehir Cam and Sakura City Hospital, Gastroenterological Surgery Clinic, Istanbul, Turkey. We retrospectively analyzed patients who underwent colonoscopy with serum lipid profile within one month for a one-year period. Groups were analyzed in terms of the correlation between hyperlipidemia and the formation of polyps. The study group was also evaluated in terms of the polyp type, localization, and number.

RESULTS

Among 453 patients, females were 248 and males were 211, with a mean age of 56.7. The study and control groups involved 259 and 194 patients, respectively. The age and serum levels of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglyceride (TG) were found to be statistically significant in terms of polyp presence and number (p < 0.05).

CONCLUSION

Colorectal polyps are well-known precursors of CRC. We found that the combination of elevated serum levels of low-density lipoprotein cholesterol, total cholesterol, and triglycerides may be a risk predictor for the presence of colorectal polyps, which can be advantageous in cancer screening.

Association between triglyceride-glucose index and colorectal polyps: A retrospective cross-sectional study

BACKGROUND

Colorectal polyps (CPs) are frequently occurring abnormal growths in the colorectum, and are a primary precursor of colorectal cancer (CRC). The triglyceride-glucose (TyG) index is a novel marker that assesses metabolic health and insulin resistance, and has been linked to gastrointestinal cancers.

AIM

To investigate the potential association between the TyG index and CPs, as the relation between them has not been documented.

METHODS

A total of 2537 persons undergoing a routine health physical examination and colonoscopy at The First People's Hospital of Kunshan, Jiangsu Province, China, between January 2020 and December 2022 were included in this retrospective cross-sectional study. After excluding individuals who did not meet the eligibility criteria, descriptive statistics were used to compare characteristics between patients with and without CPs. Logistic regression analyses were conducted to determine the associations between the TyG index and the prevalence of CPs. The TyG index was calculated using the following formula: Ln [triglyceride (mg/dL) × glucose (mg/dL)/2]. The presence and types of CPs was determined based on data from colonoscopy reports and pathology reports.

RESULTS

A nonlinear relation between the TyG index and the prevalence of CPs was identified, and exhibited a curvilinear pattern with a cut-off point of 2.31. A significant association was observed before the turning point, with an odds ratio (95% confidence interval) of 1.70 (1.40, 2.06), P < 0.0001. However, the association between the TyG index and CPs was not significant after the cut-off point, with an odds ratio (95% confidence interval) of 0.57 (0.27, 1.23), P = 0.1521.

CONCLUSION

Our study revealed a curvilinear association between the TyG index and CPs in Chinese individuals, suggesting its potential utility in developing colonoscopy screening strategies for preventing CRC.

Serum microRNA Levels as a Biomarker for Diagnosing Non-Alcoholic Fatty Liver Disease in Chinese Colorectal Polyp Patients

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and its prevalence is increasing worldwide. It is reported that NAFLD is associated with colorectal polyps. Since identifying NAFLD in its early stages could prevent possible disease progression to cirrhosis and decrease the risk of HCC by early intervention, patients with colorectal polyp may thus be considered a target group for screening NAFLD. This study aimed to investigate the potential of serum microRNAs (miRNAs) in identifying NAFLD for colorectal polyp patients. Serum samples were collected from 141 colorectal polyp patients, of which 38 had NAFLD. The serum level of eight miRNAs was determined by quantitative PCR and delta Ct values of different miRNA pairs which were compared between NAFLD and control groups. A miRNA panel was formulated from candidate miRNA pairs by multiple linear regression model and ROC analysis was performed to evaluate its diagnostic potential for NAFLD. Compared to the control group, the NAFLD group showed significantly lower delta Ct values of miR-18a/miR-16 (6.141 vs. 7.374, p = 0.009), miR-25-3p/miR-16 (2.311 vs. 2.978, p = 0.003), miR-18a/miR-21-5p (4.367 vs. 5.081, p = 0.021) and miR-18a/miR-92a-3p (8.807 vs. 9.582, p = 0.020). A serum miRNA panel composed of these four miRNA pairs significantly identified NAFLD in colorectal polyp patients with an AUC value of 0.6584 (p = 0.004). The performance of the miRNA panel was further improved to an AUC value of 0.8337 (p < 0.0001) when polyp patients with other concurrent metabolic disorders were removed from the analysis. The serum miRNA panel is a potential diagnostic biomarker for screening NAFLD in colorectal polyp patients. This serum miRNA test could be performed for colorectal polyp patients for early diagnosis and for prevention of the disease from progressing into more advanced stages.

Insulin levels are associated with risk of colon adenoma and not nonadenomatous polyps: A retrospective, hospital-based study

Recently, the prevalence of colorectal cancer has been increasing in Korea. Several studies have reported that adenomatous polyps, known as precancerous lesions, are associated with increased blood insulin levels. The principal objective of the present study was to examine the correlation between insulin levels and colon polyps in subjects without a history of diabetes or colorectal cancer. From January 2, 2018 to December 31, 2019, 3277 adults who visited the University Hospital Health Examination Center and underwent colonoscopy were included in this study. Insulin, glycated hemoglobin (HbA1c), and fasting blood glucose levels were measured, and past medical history, alcohol consumption, smoking, and physical activity were assessed using self-administered questionnaires. Among the 3277 subjects, the prevalence of adenomatous and nonadenomatous lesions were 22.2% and 11.5%, respectively. The mean values of insulin, HbA1c, and fasting blood glucose were significantly increased in the adenomatous and nonadenomatous polyp groups compared to the normal group. Logistic regression analysis showed that the risk of adenoma (odds ratio [OR] 1.483; 95% confidence interval [CI], 1.170-1.878) and nonadenomatous polyps (OR 1.415; 95% CI, 1.038-1.929) were increased in the high insulin level group (≥7.36 uIU/mL), and only the risk of adenoma (OR 1.312; 95% CI, 1.003-1.718) was significantly higher after adjustment for disturbance variables. This study suggests that an increase in insulin levels is a significant risk factor for colon adenoma.

Comprehensive transcriptome analysis of colorectal cancer risk of hyperglycemia in humans

BACKGROUND

Epidemiological studies have found that hyperglycemia, is an independent risk factor for colorectal cancer (CRC), increasing colon cancer incidence and affecting the recurrence, metastasis, and prognosis in colon cancer patients. However, the intercorrelation between hyperglycemia and CRC risk is still unknown, In the present study, we sought to determine whether gene markers, which act in CRC with hyperglycemia, are silenced in CRC without hyperglycemia.

METHODS

In order to characterize the mechanism of functional genes associated with CRC with hyperglycemia, A total 24 CRC and matched controls were sequenced. Through bioinformatics analysis includes differential expression analysis, functional enrichment, new isoform prediction and alternative splicing event identification to found biomarker genes related to CRC development.

RESULTS

CRC patients with hyperglycemia were compared with patients without hyperglycemia, and we found that 21 genes were upregulated and 27 were downregulated. Further study showed that these genes are possibly of key genes involved in CRC development with hyperglycemia, such as mannan-binding lectin-associated serine protease 3 (MASP3), which has an immunological role in the activation of the complement system. Based on our comprehensive analysis, a cis-regulatory network for hyperglycemic CRC was reconstructed.

CONCLUSIONS

Protein-protein interactions revealed the mechanisms of molecules involved in the interaction of hyperglycemia and cancer development. Our results provide further information on the metabolic pathway interaction with cancer pathways and elucidated the mechanisms of hyperglycemic factors function in cancer development from a transcriptomic perspective.

Combination treatment strategies with a focus on rosiglitazone and adriamycin for insulin resistant liver cancer

Insulin resistance promotes the occurrence of liver cancer and decreases its chemosensitivity. Rosiglitazone (ROSI), a thiazolidinedione insulin sensitiser, could be used for diabetes with insulin resistance and has been reported to show anticancer effects on human malignant cells. In this paper, we investigated the combination of ROSI and chemotherapeutics on the growth and metastasis of insulin-resistant hepatoma. In vitro assay, ROSI significantly enhanced the inhibitory effects of adriamycin (ADR) on the proliferation, autophagy and migration of insulin-resistant hepatoma HepG2/IR cells via downregulation of EGFR/ERK and AKT/mTOR signalling pathway. In addition, ROSI promoted the apoptosis of HepG2/IR cells induced by ADR. In vivo assay, high fat and glucose diet and streptozotocin (STZ) induced insulin resistance in mice by increasing the body weight, fasting blood glucose (FBG) level, oral glucose tolerance, fasting insulin level and insulin resistance index. Both the growth of mouse liver cancer hepatoma H22 cells and serum FBG level in insulin resistant mice were significantly inhibited by combination of ROSI and ADR. Thus, ROSI and ADR in combination showed a stronger anti-tumour effect in insulin resistant hepatoma cells accompanying with glucose reduction and might represent an effective therapeutic strategy for liver cancer accompanied with insulin resistant diabetes.

Elevated serum triglyceride predicts recurrence of colorectal polyps in patients with advanced adenomas

Background

Recurrence of colorectal polyps is common and impacted by various factors. This study was performed to explore the association between lipid profiles and recurrence of colorectal polyps.

Methods

This study retrospectively analyzed the lipid profiles of 435 patients who underwent colonoscopy with removal of colorectal polyps and assessed recurrence of polyps by follow-up colonoscopy. Multivariate regression logistic analysis was used to evaluate the association between lipid profiles and polyp recurrence.

Results

During the 1.5-year follow-up, recurrence of colorectal polyps was observed in 135 of 435 patients (30.34%). Patients with recurrent polyps showed a higher level of triglycerides (P = 0.006) and lower levels of high-density lipoprotein cholesterol (P = 0.008) and apolipoprotein A1 (P = 0.033). The multivariate regression logistic model suggested that an elevated triglyceride level was an independent risk factor for polyp recurrence (odds ratio, 1.55; 95% confidence interval, 1.02–2.35; P = 0.039) in patients with advanced adenoma.

Conclusions

Lipid profiles are associated with recurrence of colorectal polyps. An elevated triglyceride level is an independent risk predictor of polyp recurrence in patients with advanced adenoma.

Association between dietary sugar intake and colorectal adenoma among cancer screening examinees in Japan

Although intake of highly sugary foods is considered to be a potential risk factor for colorectal cancer through hyperinsulinemia, the association of sugar intake and colorectal adenoma, a precursor lesion to most colorectal cancer, is poorly understood, particularly in Asian populations. We undertook a cross‐sectional study in a Japanese population to investigate the association between dietary sugar intake and the prevalence of colorectal adenoma. Study subjects were selected from participants who underwent magnifying colonoscopy with dye spraying as part of a cancer screening program and who responded to a self‐administered questionnaire before the colonoscopy. A total of 738 cases with colorectal adenoma and 697 controls were enrolled. Dietary intakes of glucose, fructose, galactose, sucrose, maltose, lactose, and total sugars (sum of these six mono‐ or disaccharides) were calculated from a food frequency questionnaire, and divided into quartiles based on the distribution among controls. Odds ratios and 95% confidence intervals of colorectal adenoma were estimated using unconditional logistic regression models, with adjustment for potential confounding factors. Total sugar intake was not significantly associated with the prevalence of colorectal adenoma (odds ratio for the highest intake group compared to reference group = 1.18; 95% confidence interval, 0.81‐1.73; P for trend = .34). Furthermore, no statistically significant positive associations were observed for any of the six mono‐ or disaccharides. Findings were similar on additional analyses by site, size, and number of adenomas. Our findings do not support an association between high sugar intake and increased odds ratios of colorectal adenoma.

Plasma Biomarkers of Insulin and the Insulin-like Growth Factor Axis, and Risk of Colorectal Adenoma and Serrated Polyp

BACKGROUND

Hyperinsulinemia, high insulin-like growth factor 1 (IGF1) levels, and low IGF binding protein 1 (IGFBP1) levels have been implicated in the relationship between obesity and increased risk of colorectal cancer (CRC). However, it remains inconclusive whether circulating biomarkers of insulin and the IGF axis are associated with conventional adenoma and serrated polyp, the two distinct groups of CRC precursors.

METHODS

We prospectively examined the associations of plasma C-peptide, IGF1, IGFBP1, IGFBP3, and IGF1 to IGFBP3 ratio with conventional adenoma and serrated polyp among 11 072 women from the Nurses' Health Studies. Multivariable logistic regression was used to calculate the odds ratio (OR) per 1-SD increase in each biomarker for overall risk of conventional adenoma and serrated polyp and according to polyp feature.

RESULTS

During 20 years of follow-up, we documented 1234 conventional adenomas and 914 serrated polyps. After adjusting for various lifestyle factors (including body mass index), higher concentrations of IGFBP1 were associated with lower risk of serrated polyp (OR = 0.84, 95% confidence interval = 0.75 to 0.95, P = .005). The association was particularly strong for large serrated polyp (≥10 mm) located in the distal colon and rectum (OR = 0.59, 95% confidence interval = 0.39 to 0.87, P = .01). In contrast, we did not find any statistically significant association between the biomarkers and conventional adenoma.

CONCLUSIONS

A higher plasma level of IGFBP1 was associated with lower risk of serrated polyp. Our findings support a potential role of IGFBP1 in the serrated pathway of CRC in women.

Association of Adipokines and Insulin, Which Have a Role in Obesity, with Colorectal Cancer

Obesity-related diseases are an important part of public health; and obesity is related with colorectal cancer. Adipocyte hypertrophy and visceral adipose tissue accumulation can cause adipocitis-related diseases and pathogenic adipocyte formation. Adipose tissue has a very important and active role in immune response formation. Cytokines/adipokines, which are secreted from adipose tissue, have an active role in communication between adipocytes and macrophages. Thus, visceral adipocyte is related with low-grade chronic systemic inflammation. Adipocytes have an important role in colorectal cancer pathogenesis because of proinflammatory cytokines, growth factors, and hormones secretion. Most highlighted cytokines are adiponectin, resistin, and ghrelin. Also, insulin resistance, glucose intolerance, increased plasma insulin levels, body mass index, insulin-like growth factor (IGF-1), glucose, and serum free fatty acids levels are considered to be related with colorectal cancer pathogenesis. Thus, in this review, we focus on the role of adipokines and insulin in colorectal cancer.

Insulin-like Growth Factor II: An Essential Adult Stem Cell Niche Constituent in Brain and Intestine

Tissue-specific stem cells have unique properties and growth requirements, but a small set of juxtacrine and paracrine signals have been identified that are required across multiple niches. Whereas insulin-like growth factor II (IGF-II) is necessary for prenatal growth, its role in adult stem cell physiology is largely unknown. We show that loss of Igf2 in adult mice resulted in a ∼50% reduction in slowly dividing, label-retaining cells in the two regions of the brain that harbor neural stem cells. Concordantly, induced Igf2 deletion increased newly generated neurons in the olfactory bulb accompanied by hyposmia, and caused impairments in learning and memory and increased anxiety. Induced Igf2 deletion also resulted in rapid loss of stem and progenitor cells in the crypts of Lieberkühn, leading to body-weight loss and lethality and the inability to produce organoids in vitro. These data demonstrate that IGF-II is critical for multiple adult stem cell niches.

Intestinal insulin/IGF1 signalling through FoxO1 regulates epithelial integrity and susceptibility to colon cancer

Obesity promotes the development of insulin resistance and increases the incidence of colitis-associated cancer (CAC), but whether a blunted insulin action specifically in intestinal epithelial cells (IECs) affects CAC is unknown. Here, we show that obesity impairs insulin sensitivity in IECs and that mice with IEC-specific inactivation of the insulin and IGF1 receptors exhibit enhanced CAC development as a consequence of impaired restoration of gut barrier function. Blunted insulin signalling retains the transcription factor FOXO1 in the nucleus to inhibit expression of Dsc3, thereby impairing desmosome formation and epithelial integrity. Both IEC-specific nuclear FoxO1ADA expression and IEC-specific Dsc3 inactivation recapitulate the impaired intestinal integrity and increased CAC burden. Spontaneous colonic tumour formation and compromised intestinal integrity are also observed upon IEC-specific coexpression of FoxO1ADA and a stable Myc variant, thus suggesting a molecular mechanism through which impaired insulin action and nuclear FOXO1 in IECs promotes CAC.

Insulin Receptor Isoforms in Cancer

The insulin receptor (IR) mediates both metabolic and mitogenic effects especially when overexpressed or in clinical conditions with compensatory hyperinsulinemia, due to the metabolic pathway resistance, as obesity diabetes. In many cancers, IR is overexpressed preferentially as IR-A isoform, derived by alternative splicing of exon 11. The IR-A overexpression, and the increased IR-A:IR-B ratio, are mechanisms that promote the mitogenic response of cancer cells to insulin and IGF-2, which is produced locally by both epithelial and stromal cancer cells. In cancer IR-A, isoform predominance may occur for dysregulation at both mRNA transcription and post-transcription levels, including splicing factors, non-coding RNAs and protein degradation. The mechanisms that regulate IR isoform expression are complex and not fully understood. The IR isoform overexpression may play a role in cancer cell stemness, in tumor progression and in resistance to target therapies. From a clinical point of view, the IR-A overexpression in cancer may be a determinant factor for the resistance to IGF-1R target therapies for this issue. IR isoform expression in cancers may have the meaning of a predictive biomarker and co-targeting IGF-1R and IR-A may represent a new more efficacious treatment strategy.

The effects of physical activity on survival in patients with colorectal cancer

Mortality from colorectal cancer has been declining over the past 20 years due to improvements in screening and treatment. Physical activity improves patient quality of life, slows functional decline, and reduces all-cause mortality. Although some patients may have difficulty participating in physical activity, clinicians should always try to incorporate exercise into a management plan for patients who have survived colorectal cancer.

PGC-1α as a Biomarker of Physical Activity-Protective Effect on Colorectal Cancer

Colorectal cancer is a significant public health concern. As a multistage and multifactorial disease, environmental and genetic factors interact at each stage of the process, and an individual's lifestyle also plays a relevant role. We set out to review the scientific evidence to study the need to investigate the role of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) gene as a biomarker of the physical activity's (PA) effect on colorectal cancer. PA is a protective factor against colorectal cancer and usually increases the expression of PGC-1α This gene has pleiotropic roles and is the main regulator of mitochondrial functions. The development of colorectal cancer has been associated with mitochondrial dysfunction; in addition, alterations in this organelle are associated with colorectal cancer risk factors, such as obesity, decreased muscle mass, and the aging process. These are affected by PA acting, among other aspects, on insulin sensitivity and oxygen reactive species/redox balance. Therefore, this gene demands special attention in the understanding of its operation in the consensual protective effect of PA in colorectal cancer. A significant amount of indirect evidence points to PGC-1α as a potential biomarker in the PA-protective effect on colorectal cancer. The article focuses on the possible involvement of PGC-1α in the protective role that physical activity has on colorectal cancer. This is an important topic both in relation to advances in prevention of the development of this widespread disease and in its therapeutic treatment. We hope to generate an initial hypothesis for future studies associated with physical activity-related mechanisms that may be involved in the development or prevention of colorectal cancer. PGC-1α is highlighted because it is the main regulator of mitochondrial functions. This organelle, on one hand, is positively stimulated by physical activity; on the other hand, its dysfunction or reduction increases the probability of developing colorectal cancer. Therefore, we consider the compilation of existing information about the possible ways to understand the mechanisms of this gene to be highly relevant. This study is based on evidence of PGC-1α and physical activity, on PGC-1α and colorectal cancer, on colorectal cancer and physical activity/inactivity, and the absence of studies that have sought to relate all of these variables. Cancer Prev Res; 11(9); 523-34. ©2018 AACR.

IRS-2 rs1805097 polymorphism is associated with the decreased risk of colorectal cancer

Recent studies explored the association between insulin receptor substrate-2 (IRS-2) gene rs1805097 polymorphism and colorectal cancer (CRC) with contradictory findings. Therefore, we conducted a comprehensive meta-analysis by searching the databases of PubMed and Embase. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using fixed-effect or random-effect models. A total of 5 citations containing 6 case-control studies involving 4,333 cases and 5,333 controls were included. Our data indicated that IRS-2 rs1805097 polymorphism was associated with decreased risk of CRC. Stratification analysis of ethnicity found that rs1805097 polymorphism decreased the risk of CRC among Americans. Stratification analysis of cancer type suggested that this polymorphism decreased the risk of colon cancer. In summary, this meta-analysis indicates that IRS-2 gene rs1805097 polymorphism plays an important role in the pathogenesis of CRC.

Current perspectives between metabolic syndrome and cancer

Metabolic syndrome is a cluster of risk factors that lead to cardiovascular morbidity and mortality. Recent studies linked metabolic syndrome and several types of cancer. Although metabolic syndrome may not necessarily cause cancer, it is linked to poorer cancer outcomes including increased risk of recurrence and overall mortality. This review tends to discuss the major biological and physiological alterations involved in the increase of incidence and mortality of cancer patients affected by metabolic syndrome. We focus on metabolic syndrome-associated visceral adiposity, hyperinsulinemia, hyperglycemia, insulin-like growth factor (IGF-I) pathway as well as estrogen signaling and inflammation. Several of these factors are also involved in carcinogenesis and cancer progression. A better understanding of the link between metabolic syndrome and cancer may provide new insight about oncogenesis. Moreover, prevention of metabolic syndrome - related alterations may be an important aspect in the management of cancer patients during simultaneous palliative care.

Insulin Receptor Isoforms in Physiology and Disease: An Updated View

The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.

Impact of non-alcoholic fatty liver disease and smoking on colorectal polyps

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) and smoking have similar mechanisms of promoting colorectal polyps. The potential link between NAFLD and smoking in men and colorectal polyps has not been adequately evaluated. The aim is to investigate this association.

METHODS

A retrospective cross-sectional study was conducted on 2409 individuals undergoing a health check. Univariate and multivariate logistic regression were performed for analyzing the association between risk factors and colorectal polyps. Individuals were divided into four groups: Q1: NAFLD (-)/smoking (-); Q2: NAFLD (+)/smoking (-); Q3: NAFLD (-)/smoking (+); Q4: NAFLD (+)/smoking (+). Logistic analyses were used to explore associations for the whole study population and stratified groups.

RESULTS

The prevalence of colorectal polyps was 38.8% in males, and that of colorectal polyps in smokers and individuals with NAFLD were 47.0% (428/911) and 42.9% (267/622), respectively. With Q1 as reference, subjects with NAFLD (+) and smoking habits (+) had the highest ORs for colorectal polyps (OR = 2.64, 95% CI: 1.91 - 3.64, P < 0.001), adenomatous polyps (OR = 2.06, 95% CI: 1.38 - 3.05, P < 0.05), non-adenomatous polyps (OR = 1.97, 95% CI: 1.39 - 2.80, P < 0.05), ≥ 3 polyps (OR = 2.05, 95% CI: 1.31 - 3.22, P < 0.05) and proximal polyps (OR = 1.58, 95% CI: 1.02 - 2.45, P < 0.05) after adjusting for confounding variables.

CONCLUSIONS

Men with NAFLD and smoking habits have an increasing risk of colorectal polyps.

Alpha-glucosidase inhibitor use is associated with decreased colorectal neoplasia risk in patients with type 2 diabetes mellitus receiving colonoscopy: a retrospective study

Purpose

The purpose of this study was to clarify the factors that influence the incidence of colorectal neoplasia in patients with type 2 diabetes mellitus (DM).

Study Design and Setting

Among a total of 1176 patients who underwent total colonoscopy at our hospital, we retrospectively analyzed 168 patients with type 2 DM. Univariate and multivariate logistic regression analyses were then performed to identify the risk factors associated with colorectal neoplasia.

Results

A multivariate analysis of these patients demonstrated that male gender (odds ratio [OR] = 4.04, 95% confidence interval [CI] = 1.67-10.37, p = 0.002), taking statins (OR = 4.59, 95% CI = 1.69-13.43, p = 0.003), taking alpha glucosidase inhibitor (α-GI) (OR = 0.35, 95% CI = 0.13-0.87, p = 0.023) and taking low-dose aspirin (LDA) (OR = 0.32, 95% CI = 0.10-0.95, p = 0.040) were independent factors associated with an increased (male gender and statins) or decreased (α-GI and LDA) risk of colorectal neoplasia.

Conclusions

While male gender and taking statins are risk factors, taking α-GI as well as LDA may reduce the risk of colorectal neoplasia in patients with type2 DM.

Parameters of Glucose and Lipid Metabolism Affect the Occurrence of Colorectal Adenomas Detected by Surveillance Colonoscopies

PURPOSE

Limited data are available regarding the associations between parameters of glucose and lipid metabolism and the occurrence of metachronous adenomas. We investigated whether these parameters affect the occurrence of adenomas detected on surveillance colonoscopy.

MATERIALS AND METHODS

This longitudinal study was performed on 5289 subjects who underwent follow-up colonoscopy between 2012 and 2013 among 62171 asymptomatic subjects who underwent an initial colonoscopy for a health check-up between 2010 and 2011. The risk of adenoma occurrence was assessed using Cox proportional hazards modeling.

RESULTS

The mean interval between the initial and follow-up colonoscopy was 2.2±0.6 years. The occurrence of adenomas detected by the follow-up colonoscopy increased linearly with the increasing quartiles of fasting glucose, hemoglobin A1c (HbA1c), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and triglycerides measured at the initial colonoscopy. These associations persisted after adjusting for confounding factors. The adjusted hazard ratios for adenoma occurrence comparing the fourth with the first quartiles of fasting glucose, HbA1c, insulin, HOMA-IR, and triglycerides were 1.50 [95% confidence interval (CI), 1.26-1.77; p(trend)<0.001], 1.22 (95% CI, 1.04-1.43; p(trend)=0.024), 1.22 (95% CI, 1.02-1.46; p(trend)=0.046), 1.36 (95% CI, 1.14-1.63; p(trend)=0.004), and 1.19 (95% CI, 0.99-1.42; p(trend)=0.041), respectively. In addition, increasing quartiles of low-density lipoprotein-cholesterol and apolipoprotein B were associated with an increasing occurrence of adenomas.

CONCLUSION

The levels of parameters of glucose and lipid metabolism were significantly associated with the occurrence of adenomas detected on surveillance colonoscopy. Improving the parameters of glucose and lipid metabolism through lifestyle changes or medications may be helpful in preventing metachronous adenomas.

Randomized Pharmacokinetic Crossover Study Comparing 2 Curcumin Preparations in Plasma and Rectal Tissue of Healthy Human Volunteers

Curcumin is poorly absorbed, which is interest in new preparations. However, little is known about variations in its pharmacokinetics and tissue bioavailability between formulations. In this randomized, crossover study we evaluated the relationship between steady-state plasma and rectal tissue curcuminoid concentrations using standard and phosphatidylcholine curcumin extracts. There was no difference in the geometric mean plasma AUCs when adjusted for the 10-fold difference in curcumin dose between the 2 formulations. Phosphatidylcholine curcumin extract yielded only 20% to 30% plasma demethoxycurcumin and bisdemethoxycurcumin conjugates compared to standard extract, yet yielded 20-fold greater hexahydrocurcumin. When adjusting for curcumin dose, tissue curcumin concentrations were 5-fold greater for the phosphatidylcholine extract. Improvements in curcuminoid absorption due to phosphatidylcholine are not uniform across the curcuminoids. Furthermore, curcuminoid exposures in the intestinal mucosa are most likely due to luminal exposure rather than to plasma disposition. Finally, once-daily dosing is sufficient to maintain detectable curcuminoids at steady state in both plasma and rectal tissues.

Diabetes prevention: Reproductive age women affected by insulin resistance

In the United States, 29.1 million people are affected by diabetes, of which 95% have type 2 diabetes. There has been a fivefold increase in type 2 diabetes in the latter half of the 20th century, an increase strongly linked to the obesity epidemic in the United States. In addition, insulin resistance affects 86 million Americans, or more than one-third of the adult population, as manifested by impaired fasting glucose tolerance with random glucose values ranging from ⩾100 to <126 mg/dL. In all, 90% of those affected by impaired fasting glucose tolerance or pre-diabetes are unaware of their metabolic derangement. Although impaired fasting glucose tolerance increases one's risk of developing type 2 diabetes, once identified, application of lifestyle changes by affected individuals may avoid or delay the onset of type 2 diabetes. For reproductive age women who are found to have impaired fasting glucose tolerance, lifestyle changes may be an effective tool to diminish the reproductive health consequences of insulin resistance related diseases.

mTOR-Independent autophagy inducer trehalose rescues against insulin resistance-induced myocardial contractile anomalies: Role of p38 MAPK and Foxo1

Insulin resistance is associated with cardiovascular diseases although the precise mechanisms remain elusive. Akt2, a critical member of the Akt family, plays an essential role in insulin signaling. This study was designed to examine the effect of trehalose, an mTOR-independent autophagy inducer, on myocardial function in an Akt2 knockout-induced insulin resistance model. Adult WT and Akt2 knockout (Akt2(-/-)) mice were administered trehalose (1mg/g/day, i.p.) for two days and were then given 2% trehalose in drinking water for two more months. Echocardiographic and myocardial mechanics, intracellular Ca(2+) properties, glucose tolerance, and autophagy were assessed. Apoptosis and ER stress were evaluated using TUNEL staining, Caspase 3 assay and Western blot. Autophagy and autophagy flux were examined with a focus on p38 mitogen activated protein kinase (MAPK), Forkhead box O (Foxo1) and Akt. Akt2 ablation impaired glucose tolerance, myocardial geometry and function accompanied with pronounced apoptosis, ER stress and dampened autophagy, the effects of which were ameliorated by trehalose treatment. Inhibition of lysosomal activity using bafilomycin A1 negated trehalose-induced induction of autophagy (LC3B-II and p62). Moreover, phosphorylation of p38 MAPK and Foxo1 were upregulated in Akt2(-/-) mice, the effect of which was attenuated by trehalose. Phosphorylation of Akt was suppressed in Akt2(-/-) mice and was unaffected by trehalose. In vitro findings revealed that the p38 MAPK activator anisomycin and the Foxo1 inhibitor (through phosphorylation) AS1842856 effectively masked trehalose-offered beneficial cardiomyocyte contractile response against Akt2 ablation. These data suggest that trehalose may rescue against insulin resistance-induced myocardial contractile defect and apoptosis, via autophagy associated with dephosphorylation of p38 MAPK and Foxo1 without affecting phosphorylation of Akt.

Factors that Affect Pancreatic Islet Cell Autophagy in Adult Rats: Evaluation of a Calorie-Restricted Diet and a High-Fat Diet

Aging may be a risk factor for type 2 diabetes in the elderly. Dietary intervention can affect glucose tolerance in adults, which may be due to body composition and islet cell autophagy. The aim of this study was to determine the effects of various dietary interventions on islet cell autophagy. Pancreatic tissue and blood samples were collected from Sprague Dawley rats (14–16 months old, n = 15 for each group) that received a normal diet (ND), a high-fat diet (HFD), or a calorie-restricted diet (CRD). The body weight (BW), visceral fat, serum lipid levels, fasting serum glucose, insulin levels, and β/α cell area were determined in 14-16-(0-w), 16-18-(8-w), and 18-20(16-w)-month-old rats. Pancreatic islet autophagy (LC3B and LAMP2), AP (Acid Phosphatase) and apoptosis (apoptosis index, AI (TUNEL assay) and cleaved caspase-3) were detected using immunohistochemistry, ELISA and western blot. At 16 weeks, the expressions of LC3B, LAMP2 and AP markedly increased in both the HFD (P<0.01) and CRD (P<0.05) groups; however, an increase in the AI (P<0.05), cleaved caspase-3 and Beclin1 expression and a decrease in the expressions of BCL2 and BCLXL (P<0.05) were observed in only the HFD group. FFA, triglyceride levels, HOMA-IR, insulin levels and glucagon levels were significantly increased in the HFD group but decreased in the CRD group at 16 weeks (P<0.05). The degree of islet cell autophagy was potentially regulated by the levels of FFA and islet cell insulin and glucagon, which may have been due to the effects of Beclin1/BCL2.

Metformin Protects Kidney Cells From Insulin-Mediated Genotoxicity In Vitro and in Male Zucker Diabetic Fatty Rats

Hyperinsulinemia is thought to enhance cancer risk. A possible mechanism is induction of oxidative stress and DNA damage by insulin, Here, the effect of a combination of metformin with insulin was investigated in vitro and in vivo. The rationales for this were the reported antioxidative properties of metformin and the aim to gain further insights into the mechanisms responsible for protecting the genome from insulin-mediated oxidative stress and damage. The comet assay, a micronucleus frequency test, and a mammalian gene mutation assay were used to evaluate the DNA damage produced by insulin alone or in combination with metformin. For analysis of antioxidant activity, oxidative stress, and mitochondrial disturbances, the cell-free ferric reducing antioxidant power assay, the superoxide-sensitive dye dihydroethidium, and the mitochondrial membrane potential-sensitive dye 5,5',6,6'tetrachloro-1,1',3,3'-tetraethylbenzimidazol-carbocyanine iodide were applied. Accumulation of p53 and pAKT were analyzed. As an in vivo model, hyperinsulinemic Zucker diabetic fatty rats, additionally exposed to insulin during a hyperinsulinemic-euglycemic clamp, were treated with metformin. In the rat kidney samples, dihydroethidium staining, p53 and pAKT analysis, and quantification of the oxidized DNA base 8-oxo-7,8-dihydro-2'-deoxyguanosine were performed. Metformin did not show intrinsic antioxidant activity in the cell-free assay, but protected cultured cells from insulin-mediated oxidative stress, DNA damage, and mutation. Treatment of the rats with metformin protected their kidneys from oxidative stress and genomic damage induced by hyperinsulinemia. Metformin may protect patients from genomic damage induced by elevated insulin levels. This may support efforts to reduce the elevated cancer risk that is associated with hyperinsulinemia.

Obesity and intestinal epithelial deletion of the insulin receptor, but not the IGF 1 receptor, affect radiation-induced apoptosis in colon

Current views suggest that apoptosis eliminates genetically damaged cells that may otherwise form tumors. Prior human studies link elevated insulin and reduced apoptosis to risk of colorectal adenomas. We hypothesized that hyperinsulinemia associated with obesity would lead to reduced colon epithelial cell (CEC) apoptosis after radiation and that this effect would be altered by deletion of the insulin-like growth factor (IGF) 1 receptor (IGF1R) or the insulin receptor (IR). Mice with villin-Cre-mediated IGF1R or IR deletion in CECs and floxed littermates were fed a high-fat diet to induce obesity and hyperinsulinemia or control low-fat chow. Mice were exposed to 5-Gy abdominal radiation to induce DNA damage and euthanized 4 h later for evaluation of apoptosis by localization of cleaved caspase-3. Obese mice exhibited decreased apoptosis of genetically damaged CECs. IGF1R deletion did not affect CEC apoptosis in lean or obese animals. In contrast, IR loss increased CEC apoptosis in both diet groups but did not prevent antiapoptotic effects of obesity. Levels of p53 protein were significantly reduced in CECs of obese mice with intact IR but increased in both lean and obese mice without IR. Levels of mRNAs encoding proapoptotic Perp and the cell cycle inhibitor Cdkn1b/p27 were reduced in CECs of obese mice and increased in lean mice lacking IR. Together, our studies provide novel evidence for antiapoptotic roles of obesity and IR, but not IGF1R, in colonic epithelium after DNA damage. However, neither IR nor IGF1R deletion prevented a reduction in radiation-induced CEC apoptosis during obesity and hyperinsulinemia.

Associations Between Parameters of Glucose and Lipid Metabolism and Risk of Colorectal Neoplasm

BACKGROUND

Diabetes and dyslipidemia have been linked to an increased risk of colorectal neoplasm (CRN). However, previous studies evaluating these associations have shown inconsistent results, and large-scale studies are few in number.

AIM

To investigate the associations between the parameters of glucose and lipid metabolism and the presence of CRN.

METHODS

A cross-sectional study was performed on 38,490 Korean adults aged ≥30 years undergoing their first colonoscopy as part of routine preventive health care between 2010 and 2011.

RESULTS

The prevalence of overall CRN increased with increasing levels of glucose, hemoglobin A1c (HbA1c), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B (ApoB) and with decreasing level of apolipoprotein A1 (ApoA1). The adjusted prevalence ratios for overall CRN comparing the fourth with the first quartiles of fasting glucose, HbA1c, insulin, HOMA-IR, triglycerides, total cholesterol, LDL-C, ApoB, and ApoA-1 were 1.83 (95% CI 1.62-2.06), 1.17 (95% CI 1.03-1.33), 1.09 (95% CI 0.97-1.23), 1.22 (95% CI 1.08-1.37), 1.31 (95% CI 1.16-1.48), 1.19 (95 % CI 1.07-1.33), 1.38 (95% CI 1.23-1.54), 1.30 (95% CI 1.14-1.47), and 0.85 (95% CI 0.76-0.95), respectively. There was also a significant association between higher levels of glucose, LDL-C, and ApoB with a higher prevalence of advanced CRN. Moreover, the risk of CRN increased further in cases in which the parameters of glucose metabolism and lipid metabolism worsened simultaneously.

CONCLUSIONS

The levels of parameters of glucose and lipid metabolism are significantly associated with the prevalence of CRN. Altered glucose and lipid metabolism may contribute to the development of CRN.

Hyperinsulinemia, insulin resistance and colorectal adenomas: A meta-analysis

BACKGROUND

Insulin stimulates cell proliferation and inhibits apoptosis. While epidemiologic studies have investigated associations between markers of insulin resistance/hyperinsulinemia (i.e., circulating insulin, homeostasis model assessment-insulin resistance (HOMA-IR), C-peptide) and risk of colorectal adenoma (CRA), the effect size has not yet been quantified.

OBJECTIVE

We aimed to summarize the association between hyperinsulinemia/insulin resistance and risk of CRA, including whether the association is independent of adiposity.

MATERIALS AND METHODS

Pubmed and Embase were searched through April, 2015 to identify observational studies investigating the associations between insulin, C-peptide and HOMA-IR and CRA risk. Using the highest versus lowest category meta-analysis and dose-response meta-analysis based on a random-effects model, we estimated summary odds ratio (OR) and the corresponding 95% confidence interval (95% CI).

RESULTS

A total of 27 studies (insulin: 16 studies including 14,007 cases; C-peptide: 11 studies including 8639 cases; HOMA-IR: 8 studies including 11,619 cases) were included in this meta-analysis. The summary ORs of CRA comparing the highest with the lowest quantile were 1.33 for insulin (95% CI=1.12-1.58, I(2)=73.9%, Pheterogeneity<0.001), 1.44 for C-peptide (95% CI=1.13-1.83, I(2)=63.5%, Pheterogeneity=0.003), and 1.33 for HOMA-IR (95% CI=1.10-1.60, I(2)=69.1%, Pheterogeneity=0.004). Upon stratification by ethnicity, higher levels of insulin and C-peptide were significantly associated with increased risk of CRA in non-Asian ethnicity (summary OR for insulin=1.67 [95% CI=1.28-2.17], I(2)=34.9%, Pheterogeneity=0.16; summary OR for C-peptide=1.59 [95% CI=1.22-2.08], I(2)=21.5%, Pheterogeneity=0.27) but not in Asians (summary OR for insulin=1.10 [95% CI=0.92-1.33], I(2)=76.6%, Pheterogeneity=0.001; summary OR for C-peptide=1.27 [95% CI=0.84-1.91], I(2)=72.6, Pheterogeneity=0.01). We observed evidence for the existence of publication bias for insulin (P=0.01 by Egger test) and HOMA-IR (P=0.05 by Egger test). The results were confirmed in linear dose-response meta-analysis. These significant positive associations generally persisted even after adjustment for adiposity, although the effect size was substantially attenuated.

CONCLUSIONS

Independent of adiposity, higher levels of insulin, C-peptide, and HOMA-IR were significantly associated with increased risk of CRA. The weaker associations and high heterogeneity in Asian studies warrant further research. These results indicate that insulin resistance and hyperinsulinemia may contribute in part to the association between obesity and CRA risk.

Circulating levels of IGF-1, IGFBP-3, and IGF-1/IGFBP-3 molar ratio and colorectal adenomas: A meta-analysis

BACKGROUNDS

Insulin-like growth factor-1(IGF-1) promotes cell proliferation and inhibits apoptosis, and is thereby implicated in carcinogenesis. Insulin-like growth factor binding protein-3 (IGFBP-3) may antagonize IGF-1 action, leading to inhibition of the potential tumorigenicity of IGF-1. We conducted this meta-analysis to estimate the association between IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio and the risk of colorectal adenomas (CRAs). Further, we investigated whether this association was different between occurrent and recurrent CRA, by adjustment for obesity, and by advanced CRA.

MATERIALS AND METHODS

Pubmed and Embase were searched up to April, 2015 to identify relevant observational studies and summary odds ratio (OR) and the corresponding 95% confidence interval (95% CI) was estimated using a random-effects model.

RESULTS

A total of 12 studies (11 studies including 3038 cases for IGF-1, 12 studies including 3208 cases for IGFBP-3, and 7 studies including 1867 cases for IGF-1/IGFBP-3 ratio) were included in this meta-analysis. The summary ORs of occurrent CRA for the highest versus lowest category of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio were 1.13 (95% CI: 0.95-1.34), 0.99 (0.84-1.16), and 1.05 (0.86-1.29), respectively. Higher IGF-1 and IGF-1/IGFBP-3 ratio were significantly associated with decreased risk of recurrent CRA (OR for IGF-1=0.60 [95% CI: 0.42-0.85]; IGF-1/IGFBP-3 ratio=0.65 [0.44-0.96]). A stratified analysis by advancement of occurrent CRA produced a significant summary OR of IGF-1 for advanced CRA (OR=2.21 [1.08-4.52]) but not for non-advanced CRA (OR=0.89 [0.55-1.45]). We did not find significant publication bias or heterogeneity.

CONCLUSION

Circulating levels of IGF-1, IGFBP-3 and their molar ratio were not associated with the risk of occurrence of CRA, but IGF-1 was associated with the increased risk for occurrence of advanced CRA.

Genetic and Diet-Induced Obesity Increased Intestinal Tumorigenesis in the Double Mutant Mouse Model Multiple Intestinal Neoplasia X Obese via Disturbed Glucose Regulation and Inflammation

We have studied how spontaneous or carcinogen-induced intestinal tumorigenesis was affected by genetic or diet-induced obesity in C57BL/6J-Apc (Min/+) X C57BL/6J-Lep (ob/+) mice. Obesity was induced by the obese (ob) mutation in the lep gene coding for the hormone leptin, or by a 45% fat diet. The effects of obesity were examined on spontaneous intestinal tumors caused by the multiple intestinal neoplasia (Min) mutation in the adenomatous polyposis coli (Apc) gene and on tumors induced by the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). F1 ob/ob (homozygous mutated) mice had increased body weight (bw) and number of spontaneous and PhIP-induced small intestinal tumors (in Apc (Min/+) mice), versus ob/wt (heterozygous mutated) and wt/wt mice (homozygous wild-type). A 45% fat diet exacerbated bw and spontaneous tumor numbers versus 10% fat, but not PhIP-induced tumors. Except for bw, ob/wt and wt/wt were not significantly different. The obesity caused hyperglucosemia and insulinemia in ob/ob mice. A 45% fat diet further increased glucose, but not insulin. Inflammation was seen as increased TNFα levels in ob/ob mice. Thus the results implicate disturbed glucose regulation and inflammation as mechanisms involved in the association between obesity and intestinal tumorigenesis. Ob/ob mice had shorter lifespan than ob/wt and wt/wt mice.

Aspects of dietary carbohydrate intake are not related to risk of colorectal polyps in the Tennessee Colorectal Polyp Study

PURPOSE

High digestible carbohydrate intakes can induce hyperglycemia and hyperinsulinemia and collectively have been implicated in colorectal tumor development. Our aim was to explore the association between aspects of dietary carbohydrate intake and risk of colorectal adenomas and hyperplastic polyps in a large case-control study.

METHODS

Colorectal polyp cases (n = 1,315 adenomas only, n = 566 hyperplastic polyps only and n = 394 both) and controls (n = 3,184) undergoing colonoscopy were recruited between 2003 and 2010 in Nashville, Tennessee, USA. Dietary intakes were estimated by a 108-item food frequency questionnaire. Unconditional logistic regression analysis was applied to determine odds ratios (OR) and corresponding 95 % confidence intervals (CI) for colorectal polyps according to dietary carbohydrate intakes, after adjustment for potential confounders.

RESULTS

No significant associations were detected for risk of colorectal adenomas when comparing the highest versus lowest quartiles of intake for total sugars (OR 1.03; 95 % CI 0.84-1.26), starch (OR 1.01; 95 % CI 0.81-1.26), total or available carbohydrate intakes. Similar null associations were observed between dietary carbohydrate intakes and risk of hyperplastic polyps, or concurrent adenomas and hyperplastic polyps.

CONCLUSION

In this US population, digestible carbohydrate intakes were not associated with risk of colorectal polyps, suggesting that dietary carbohydrate does not have an etiological role in the early stages of colorectal carcinogenesis.

Deletion of intestinal epithelial insulin receptor attenuates high-fat diet-induced elevations in cholesterol and stem, enteroendocrine, and Paneth cell mRNAs

The insulin receptor (IR) regulates nutrient uptake and utilization in multiple organs, but its role in the intestinal epithelium is not defined. This study developed a mouse model with villin-Cre (VC) recombinase-mediated intestinal epithelial cell (IEC)-specific IR deletion (VC-IR(Δ/Δ)) and littermate controls with floxed, but intact, IR (IR(fl/fl)) to define in vivo roles of IEC-IR in mice fed chow or high-fat diet (HFD). We hypothesized that loss of IEC-IR would alter intestinal growth, biomarkers of intestinal epithelial stem cells (IESC) or other lineages, body weight, adiposity, and glucose or lipid handling. In lean, chow-fed mice, IEC-IR deletion did not affect body or fat mass, plasma glucose, or IEC proliferation. In chow-fed VC-IR(Δ/Δ) mice, mRNA levels of the Paneth cell marker lysozyme (Lyz) were decreased, but markers of other differentiated lineages were unchanged. During HFD-induced obesity, IR(fl/fl) and VC-IR(Δ/Δ) mice exhibited similar increases in body and fat mass, plasma insulin, mRNAs encoding several lipid-handling proteins, a decrease in Paneth cell number, and impaired glucose tolerance. In IR(fl/fl) mice, HFD-induced obesity increased circulating cholesterol; numbers of chromogranin A (CHGA)-positive enteroendocrine cells (EEC); and mRNAs encoding Chga, glucose-dependent insulinotrophic peptide (Gip), glucagon (Gcg), Lyz, IESC biomarkers, and the enterocyte cholesterol transporter Scarb1. All these effects were attenuated or lost in VC-IR(Δ/Δ) mice. These results demonstrate that IEC-IR is not required for normal growth of the intestinal epithelium in lean adult mice. However, our findings provide novel evidence that, during HFD-induced obesity, IEC-IR contributes to increases in EEC, plasma cholesterol, and increased expression of Scarb1 or IESC-, EEC-, and Paneth cell-derived mRNAs.

Insulin resistance reduces sensitivity to Cis-platinum and promotes adhesion, migration and invasion in HepG2 cells

The liver is normally the major site of glucose metabolism in intact organisms and the most important target organ for the action of insulin. It has been widely accepted that insulin resistance (IR) is closely associated with postoperative recurrence of hepatocellular carcinoma (HCC). However, the relationship between IR and drug resistance in liver cancer cells is unclear. In the present study, IR was induced in HepG2 cells via incubation with a high concentration of insulin. Once the insulin-resistant cell line was established, the instability of HepG2/ IR cells was further tested via incubation in insulin-free medium for another 72h. Afterwards, the biological effects of insulin resistance on adhesion, migration, invasion and sensitivity to cis-platinum (DDP) of cells were determined. The results indicated that glucose consumption was reduced in insulin-resistant cells. In addition, the expression of the insulin receptor and glucose transportor-2 was downregulated. Furthermore, HepG2/IR cells displayed markedly enhanced adhesion, migration, and invasion. Most importantly, these cells exhibited a lower sensitivity to DDP. By contrast, HepG2/IR cells exhibited decreased adhesion and invasion after treatment with the insulin sensitizer pioglitazone hydrochloride. The results suggest that IR is closely related to drug resistance as well as adhesion, migration, and invasion in HepG2 cells. These findings may help explain the clinical observation of limited efficacy for chemotherapy on a background of IR, which promotes the invasion and migration of cancer cells.

Specific metabolic biomarkers as risk and prognostic factors in colorectal cancer

Advances in genomics, molecular pathology and metabolism have generated many candidate biomarkers of colorectal cancer with potential clinical value. Epidemiological and biological studies suggest a role for adiposity, dyslipidaemia, hyperinsulinemia, altered glucose homeostasis, and elevated expression of insulin-like growth factor (IGF) axis members in the risk and prognosis of cancer. This review discusses some recent past and current approaches being taken by researches in obesity and metabolic disorders. The authors describe three main systems as the most studied metabolic candidates of carcinogenesis: dyslipidemias, adipokines and insulin/IGF axis. However, each of these components is unsuccessful in defining the diseases risk and progression, while their co-occurrence increases cancer incidence and mortality in both men and women.

Molecular markers of carcinogenesis for risk stratification of individuals with colorectal polyps: a case-control study

Risk stratification using number, size, and histology of colorectal adenomas is currently suboptimal for identifying patients at increased risk for future colorectal cancer. We hypothesized that molecular markers of carcinogenesis in adenomas, measured via immunohistochemistry, may help identify high-risk patients. To test this hypothesis, we conducted a retrospective, 1:1 matched case-control study (n = 216; 46% female) in which cases were patients with colorectal cancer and synchronous adenoma and controls were patients with adenoma but no colorectal cancer at baseline or within 5 years of follow-up. In phase I of analyses, we compared expression of molecular markers of carcinogenesis in case and control adenomas, blind to case status. In phase II of analyses, patients were randomly divided into independent training and validation groups to develop a model for predicting case status. We found that seven markers [p53, p21, Cox-2, β-catenin (BCAT), DNA-dependent protein kinase (DNApkcs), survivin, and O6-methylguanine-DNA methyltransferase (MGMT)] were significantly associated with case status on unadjusted analyses, as well as analyses adjusted for age and advanced adenoma status (P < 0.01 for at least one marker component). When applied to the validation set, a predictive model using these seven markers showed substantial accuracy for identifying cases [area under the receiver operation characteristic curve (AUC), 0.83; 95% confidence interval (CI), 0.74-0.92]. A parsimonious model using three markers performed similarly to the seven-marker model (AUC, 0.84). In summary, we found that molecular markers of carcinogenesis distinguished adenomas from patients with and without colorectal cancer. Furthermore, we speculate that prospective studies using molecular markers to identify individuals with polyps at risk for future neoplasia are warranted.

Reduced insulin-like growth factor I receptor and altered insulin receptor isoform mRNAs in normal mucosa predict colorectal adenoma risk

BACKGROUND

Hyperinsulinemia resulting from obesity and insulin resistance is associated with increased risk of many cancers, but the biology underlying this risk is unclear. We hypothesized that increased mRNA levels of the insulin-like growth factor I receptor (IGFIR) versus the insulin receptor (IR) or elevated ratio of IR-A:IR-B isoforms in normal rectal mucosa would predict adenoma risk, particularly in individuals with high body mass index (BMI) or plasma insulin.

METHODS

Biopsies from normal rectal mucosa were obtained from consenting patients undergoing routine colonoscopy at University of North Carolina Hospitals (Chapel Hill, NC). Subjects with colorectal adenomas were classified as cases (n = 100) and were matched to adenoma-free controls (n = 98) based on age, sex, and BMI. IGFIR and IR mRNA levels were assessed by qRT-PCR, and IR-A:IR-B mRNA ratios by standard PCR. Plasma insulin and crypt apoptosis were measured by ELISA and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), respectively. Logistic regression models examined relationships between receptor mRNAs, BMI, plasma insulin, and adenoma risk.

RESULTS

Unexpectedly, cases were significantly more likely to have lower IGFIR mRNA levels than controls. No overall differences in total IR mRNA or IR-A:IR-B ratios were observed between cases and controls. Interestingly, in patients with high plasma insulin, increased IR-A:IR-B ratio was associated with increased likelihood of having adenomas.

CONCLUSIONS

Our work shows novel findings that reduced IGFIR mRNA and, during high plasma insulin, increased IR-A:IR-B ratios in normal rectal mucosa are associated with colorectal adenoma risk.

IMPACT

Our work provides evidence supporting a link between IGFIR and IR isoform expression levels and colorectal adenoma risk.

Association between markers of glucose metabolism and risk of colorectal adenoma

BACKGROUND & AIMS

Diabetes is a risk factor for colorectal cancer. We studied the association between markers of glucose metabolism and metabolic syndrome and the presence of colorectal adenomas in a large number of asymptomatic men and women attending a health screening program in South Korea. We also investigated whether these associations depend on adenoma location.

METHODS

In a cross-sectional study, we measured fasting levels of glucose, insulin, hemoglobin A1c, and C-peptide and calculated homeostatic model assessment (HOMA) values (used to quantify insulin resistance) for 19,361 asymptomatic South Korean subjects who underwent colonoscopy examinations from January 2006 to June 2009. Participants completed a standardized self-administered health questionnaire and a validated semiquantitative food frequency questionnaire. Blood samples were collected on the day of the colonoscopy; fasting blood samples were also collected. Robust Poisson regression was used to model the associations of glucose markers with the prevalence of any adenoma.

RESULTS

Using detailed multivariable-adjusted dose-response models, the prevalence ratios (aPR, 95% confidence interval [CI]) for any adenoma, comparing the 90th with the 10th percentile, were 1.08 (1.00-1.16; P = .04) for fasting glucose, 1.07 (0.99-1.15; P = .10) for insulin, 1.09 (1.02-1.18, P = .02) for HOMA, 1.09 (1.01-1.17; P = .02) for hemoglobin A1c, and 1.14 (1.05-1.24; P = .002) for C-peptide. The corresponding ratios for nonadvanced adenomas were 1.11 (0.99-1.25; P = .08), 1.10 (0.98-1.24; P = .12), 1.15 (1.02-1.29; P = .02), 1.14 (1.01-1.28; P = .03), and 1.20 (1.05-1.37; P = .007), respectively. The corresponding ratios for advanced adenomas were 1.32 (0.94-1.84; P = .11), 1.23 (0.87-1.75; P = .24), 1.30 (0.92-1.85; P = .14), 1.13 (0.79-1.61; P = .50), and 1.67 (1.15-2.42; P = .007), respectively. Metabolic syndrome was associated with the prevalence of any adenoma (aPR, 1.18; 95% CI, 1.13-1.24; P < .001), nonadvanced adenoma (aPR, 1.30; 95% CI, 1.20-1.40; P < .001), and advanced adenoma (aPR, 1.42; 95% CI, 1.14-1.78; P = .002). Associations were similar for adenomas located in the distal versus proximal colon.

CONCLUSIONS

Increasing levels of glucose, HOMA values, levels of hemoglobin A1c and C-peptide, and metabolic syndrome are significantly associated with the prevalence of adenomas. Adenomas should be added to the list of consequences of altered glucose metabolism.

Insulin therapy and colorectal cancer risk among type 2 diabetes mellitus patients: a systemic review and meta-analysis

BACKGROUND

Insulin is widely used in patients with type 2 diabetes mellitus (T2DM). More attention was focused on its higher risk of colorectal cancer (CRC). This meta-analysis examined the relationship between levels of insulin use and the risk of CRC.

METHODS

A meta-analysis using data from 12 published epidemiologic studies (7 case-control, and 5 cohort studies) published before Jan. 2014 was done to examine the association between insulin use and CRC. Random effects analyses were done to calculate relative risk (RR) and 95% confidence intervals (CI). Heterogeneity among studies was measured by the χ2 and I2 statistic.

RESULTS

Overall, the risk of CRC was significantly associated with insulin use to a random-effects model (RR, 1.69; 95% CI, 1.25 -2.27). When subgroup analyses were conducted according to the study types, no associations were detected in cohort group (RR, 1.25; 95% CI, 0.95-1.65; I2, 75.7%); however significant association was detected in case-control group (RR, 2.15; 95% CI, 1.41-3.26; I2, 89.1%).

CONCLUSIONS

A significant harmful effect of insulin, observed mainly among case-control studies, may result from study design differences and amount of included studies. Although these results suggest a harmful effect of insulin use for CRC risk, additional large studies are warranted to support these preliminary evidences.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2194715731194123.

IRS-2 G1057D polymorphism in Turkish patients with colorectal cancer

Introduction

Gene polymorphisms have a broad range of analysis, but are of particular use in molecular medicine due to their potential in revealing the genetic tendency in diseases such as cancer, heart attack etc. These studies basically depend on mutations that can be detected by proper techniques. The genes coding the insulin receptor substrate (IRS) proteins are among the most widely analysed polymorphisms in various cancer types, in which a G1057D mutation is seen.

Aim

To determine the risk of colon cancer by analysing the IRS-2 gene polymorphism in Turkish patients.

Material and methods

A total of 161 newly diagnosed colorectal cancer patients were analysed and compared to 197 unrelated healthy controls. A polymerase chain reaction-based restriction fragment length polymorphism method was carried out.

Results

No differences were observed between the patient and control groups for both allele and genotype frequencies of the IRS-2 G1057D gene.

Conclusions

Our results demonstrated that IRS-2 G1057D polymorphism is not associated with colorectal cancer in the Turkish population. This research is a preliminary and original study in Turkish patients with colorectal cancer. It also provides population-level genetic data on IRS-2 in the Turkish population. Further studies should be performed on larger number of patients and controls for more reliable results about the genetic tendency in colorectal cancer in Turkey. The study is a collaborative work of different universities and scientists.

Fasting serum insulin levels and insulin resistance are associated with colorectal adenoma in Koreans

AIMS/INTRODUCTION

Insulin has been associated with the risk of colorectal cancer (CRC). However, few studies have evaluated the association between insulin and colorectal adenoma. We investigated the relationship between fasting serum insulin levels or homeostasis model assessment of insulin resistance (HOMA-IR) and colorectal adenoma.

MATERIALS AND METHODS

We retrospectively enrolled 15,427 participants who underwent both fasting serum insulin measurement and colonoscopy for a routine health examination at Asan Medical Center from January 2007 to December 2008. Participants with a history of any cancer, previous colectomy or polypectomy, those taking antidiabetic medications, and inflammatory bowel disease, non-specific colitis, non-adenomatous polyps only or CRC on colonoscopic findings were excluded. Finally, 3,606 participants with histologically confirmed colorectal adenoma and 6,019 controls with no abnormal findings on colonoscopy were included. Participants were categorized into quartiles (Q) based on fasting serum insulin levels and HOMA-IR.

RESULTS

Fasting serum insulin and HOMA-IR were significantly higher in participants with colorectal adenomas compared with controls. Multivariate regression analysis adjusting for age, sex, smoking habits, drinking habits and family history of CRC showed that participants with higher quartiles of fasting serum insulin levels (odd ratio [OR] 1.17 for 2nd Q, 1.19 for 3rd Q, and 1.42 for 4th Q, P < 0.05) or HOMA-IR (OR 1.18 for 2nd Q and 1.45 for 4th Q, P < 0.05) showed significantly increased ORs of colorectal adenoma compared with the lowest quartiles.

CONCLUSIONS

These findings showed that increased serum insulin levels and insulin resistance were significantly associated with the presence of colorectal adenoma.

Obesity and colorectal adenomatous polyps: a cross-sectional study in Korean adults

OBJECTIVE

This study aimed to examine the association between obesity and the risk of colorectal adenomatous polyps.

DESIGN AND METHODS

The design of this study is a cross-sectional study. A total of 1,574 participants (818 males and 756 females), who had undergone colonoscopy for health examinations at the National Cancer Center hospital in South Korea from February to September 2009, were included in the analysis.

RESULTS

The prevalence of colorectal adenomatous polyps was 39.5% in males and 22.6% in females. In multiple logistic regression analysis, obesity (odds ratio [OR] = 1.69, 95% CI = 1.16-2.48) and abdominal obesity (OR = 1.59, 95% CI = 1.13-2.23) were significantly associated with an increased risk of colorectal adenomatous polyps in males, but not in females. In the subgroup analyses by age, obesity (OR = 2.27, 95% CI = 1.32-3.89), and abdominal obesity (OR = 1.76, 95% CI = 1.12-2.76) significantly increased a risk of colorectal adenomatous polyps in males aged <50 years, but not in males aged ≥50 years. However, interaction terms were not significant between obesity and gender (P = 0.397) and between obesity and age (P = 0.531) in the overall analyses.

CONCLUSION

Our findings should be explored in further research.

Racial differences in the association of insulin-like growth factor pathway and colorectal adenoma risk

PURPOSE

Insulin resistance is believed to play an important role in the link between energy imbalance and colon carcinogenesis. Emerging evidence suggests that there are substantial racial differences in genetic and anthropometric influences on insulin-like growth factors (IGFs); however, few studies have examined racial differences in the associations of IGFs and colorectal adenoma, precursor lesions of colon cancer.

METHODS

We examined the association of circulating levels of IGF-1, IGFBP-3 and IGFBP-1, and SNPs in the IGF-1 receptor (IGF1R), IGF-2 receptor (IGF2R), and insulin receptor genes with risk of adenomas in a sample of 410 incident adenoma cases and 1,070 controls from the Case Transdisciplinary Research on Energetics and Cancer (TREC) Colon Adenomas Study.

RESULTS

Caucasians have higher IGF-1 levels compared to African Americans; mean IGF-1 levels are 119.0 ng/ml (SD = 40.7) and 109.8 ng/ml (SD = 40.8), respectively, among cases (p = 0.02). Mean IGF-1 levels are also higher in Caucasian controls (122.9 ng/ml, SD = 41.2) versus African American controls (106.9, SD = 41.2), p = 0.001. We observed similar differences in IGFBP3 levels by race. Logistic regression models revealed a statistically significant association of IGF-1 with colorectal adenoma in African Americans only, with adjusted odds ratios (ORs) of 1.68 (95 % CI 1.06-2.68) and 1.68 (95 % CI 1.05-2.71), respectively, for the second and third tertiles as compared to the first tertile. One SNP (rs496601) in IGF1R was associated with adenomas in Caucasians only; the per allele adjusted OR is 0.73 (95 % CI 0.57-0.93). Similarly, one IGF2R SNP (rs3777404) was statistically significant in Caucasians; adjusted per allele OR is 1.53 (95 % CI 1.10-2.14).

CONCLUSION

Our results suggest racial differences in the associations of IGF pathway biomarkers and inherited genetic variance in the IGF pathway with risk of adenomas that warrant further study.