Republished: obesity and colorectal cancer

Single-cell transcriptome analysis reveals immunosuppressive landscape in overweight and obese colorectal cancer

BACKGROUND

Overweight and obesity are established risk factors for various types of cancers including colorectal cancer (CRC). However the underlying molecular mechanisms remain unclear. An in-depth understanding of the oncologic characteristics of overweight and obese CRC at the single-cell level can provide valuable insights for the development of more effective treatment strategies for CRC.

METHODS

We conducted single-cell RNA sequencing (scRNA-seq) analysis on tumor and adjacent normal colorectal samples from 15 overweight/obese and 15 normal-weight CRC patients. Immunological and metabolic differences between overweight/obese CRC and non-obese CRC were characterized.

RESULTS

We obtained single-cell transcriptomics data from a total of 192,785 cells across all samples. By evaluating marker gene expression patterns, we annotated nine main cell types in the CRC ecosystem. Specifically, we found that the cytotoxic function of effector T cells and NK cells was impaired in overweight/obese CRC compared with non-obese CRC, relating to its metabolic dysregulation. CD4+T cells in overweight/obese CRC exhibited higher expression of immune checkpoint molecules. The antigen-presenting ability of DCs and B cells is down-regulated in overweight/obese CRC, which may further aggravate the immunosuppression of overweight/obese CRC. Additionally, dysfunctional stromal cells were identified, potentially promoting invasion and metastasis in overweight/obese CRC. Furthermore, we discovered the up-regulated metabolism of glycolysis and lipids of tumor cells in overweight/obese CRC, which may impact the metabolism and function of immune cells. We also identified inhibitory interactions between tumor cells and T cells in overweight/obese CRC.

CONCLUSIONS

The study demonstrated that overweight/obese CRC has a more immunosuppressive microenvironment and distinct metabolic reprogramming characterized by increased of glycolysis and lipid metabolism. These findings may have implications for the development of novel therapeutic strategies for overweight/obese CRC patients.

Obesity, obesities and gastrointestinal cancers

Obesity has been recognized to be increasing globally and is designated a disease with adverse consequences requiring early detection and appropriate care. In addition to being related to metabolic syndrome disorders such as type 2 diabetes, hypertension, stroke, and premature coronary artery disease. Obesity is also etiologically linked to several cancers. The non-gastrointestinal cancers are breast, uterus, kidneys, ovaries, thyroid, meningioma, and thyroid. Gastrointestinal (GI) cancers are adenocarcinoma of the esophagus, liver, pancreas, gallbladder, and colorectal. The brighter side of the problem is that being overweight and obese and cigarette smoking are mostly preventable causes of cancers. Epidemiology and clinical studies have revealed that obesity is heterogeneous in clinical manifestations. In clinical practice, BMI is calculated by dividing a person's weight in kilograms by the square of the person's height in square meters (kg/m2). A BMI above 30 kg/m2 (defining obesity in many guidelines) is considered obesity. However, obesity is heterogeneous. There are subdivisions for obesity, and not all obesities are equally pathogenic. Adipose tissue, in particular, visceral adipose tissue (VAT), is endocrine and abdominal obesity (a surrogate for VAT) is evaluated by waist-hip measurements or just waist measures. Visceral Obesity, through several hormonal mechanisms, induces a low-grade chronic inflammatory state, insulin resistance, components of metabolic syndrome, and cancers. Metabolically obese, normal-weight (MONW) individuals in several Asian countries may have BMI below normal levels to diagnose obesity but suffer from many obesity-related complications. Conversely, some people have high BMI but are generally healthy with no features of metabolic syndrome. Many clinicians advise weight loss by dieting and exercise to metabolically healthy obese with large body habitus than to individuals with metabolic obesity but normal BMI. The GI cancers (esophagus, pancreas, gallbladder, liver, and colorectal) are individually discussed, emphasizing the incidence, possible pathogenesis, and preventive measures. From 2005 to 2014, most cancers associated with overweight and Obesity increased in the United States, while cancers related to other factors decreased. The standard recommendation is to offer or refer adults with a body mass index (BMI) of 30 or more to intensive, multicomponent behavioral interventions. However, the clinicians have to go beyond. They should critically evaluate BMI with due consideration for ethnicity, body habitus, and other factors that influence the type of obesity and obesity-related risks. In 2001, the Surgeon General's ``Call to Action to Prevent and Decrease Overweight and Obesity'' identified obesity as a critical public health priority for the United States. At government levels reducing obesity requires policy changes that improve the food and physical activity for all. However, implementing some policies with the most significant potential benefit to public health is politically tricky. The primary care physician, as well as subspecialists, should identify overweight and Obesity based on all the variable factors in the diagnosis. The medical community should address the prevention of overweight and Obesity as an essential part of medical care as much as vaccination in preventing infectious diseases at all levels- from childhood, to adolescence, and adults.

New insights into molecular pathways in colorectal cancer: Adiponectin, interleukin-6 and opioid signaling

Colorectal cancer (CRC) is one of the most common cause of death among neoplasms around the world. The environmental factors, like diet and obesity, are crucial in CRC pathogenesis by creating cancer-favorable microenvironment and hormonal changes. Adiponectin, the adipose tissue-specific hormone, is generally considered to negatively correlate with CRC development. The interleukin 6 (IL-6) is one of the most important pro-inflammatory cytokine connected with CRC, which is strongly inflammation-associated. The opioids are variable group substantially correlated with cancers - the endogenous opioids affect immune system and cell cycle including proliferation and cell death whereas exogenous opioids are leading clinically used analgesics in terminal cancer patients. In this review we discuss the involvement of adiponectin, IL-6 and opioids in CRC pathogenesis, their link with obesity, possible cross-talk and potential novel therapeutic approach in CRC treatment.

Integrated Transcriptome Analysis of Human Visceral Adipocytes Unravels Dysregulated microRNA-Long Non-coding RNA-mRNA Networks in Obesity and Colorectal Cancer

Obesity, and the obesity-associated inflammation, represents a major risk factor for the development of chronic diseases, including colorectal cancer (CRC). Dysfunctional visceral adipose tissue (AT) is now recognized as key player in obesity-associated morbidities, although the biological processes underpinning the increased CRC risk in obese subjects are still a matter of debate. Recent findings have pointed to specific alterations in the expression pattern of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), and long non-coding RNAs (lncRNAs), as mechanisms underlying dysfunctional adipocyte phenotype in obesity. Nevertheless, the regulatory networks and interrelated processes relevant for adipocyte functions, that may contribute to a tumor-promoting microenvironment, are poorly known yet. To this end, based on RNA sequencing data, we identified lncRNAs and miRNAs, which are aberrantly expressed in visceral adipocytes from obese and CRC subjects, as compared to healthy lean control, and validated a panel of modulated ncRNAs by real-time qPCR. Furthermore, by combining the differentially expressed lncRNA and miRNA profiles with the transcriptome analysis dataset of adipocytes from lean and obese subjects affected or not by CRC, lncRNA-miRNA-mRNA adipocyte networks were defined for obese and CRC subjects. This analysis highlighted several ncRNAs modulation that are common to both obesity and CRC or unique of each disorder. Functional enrichment analysis of network-related mRNA targets, revealed dysregulated pathways associated with metabolic processes, lipid and energy metabolism, inflammation, and cancer. Moreover, adipocytes from obese subjects affected by CRC exhibited a higher complexity, in terms of number of genes, lncRNAs, miRNAs, and biological processes found to be dysregulated, providing evidence that the transcriptional and post-transcriptional program of adipocytes from CRC patients is deeply affected by obesity. Overall, this study adds further evidence for a central role of visceral adipocyte dysfunctions in the obesity-cancer relationship.

Is visceral obesity associated with colorectal cancer? The first volumetric study using all CT slices

PURPOSE

We aimed to examine the possible relationship between abdominal adiposity parameters and the presence of colorectal cancer (CRC) and between these adiposity parameters and various histopathologic findings of the tumor.

METHODS

A total of 60 control subjects and 111 CRC patients, 63 with early-stage and 48 with advanced-stage disease, were enrolled. Medical data and abdominopelvic computed tomography (CT) examinations of each study group were retrospectively reviewed. Abdominal adiposity parameters, including visceral adipose tissue (VAT) volume, subcutaneous adipose tissue (SAT) volume, and total adipose tissue (TAT) volume, were calculated on all slices of the CT examinations with specialized software, and results for each study group were compared. Adiposity parameters were also compared with tumor histopathologic findings.

RESULTS

We found lower VAT and higher SAT volumes in advanced-stage CRC patients, compared with the early-stage group. However, this relationship was not statistically significant (P = 0.721 for VAT and P = 0.432 for SAT volumes). We detected significantly lower VAT and SAT volumes in the early-stage CRC group compared with the control group (P = 0.014 for both). There was no significant relationship between TAT volumes and the study groups (P = 0.06). No statistically significant relationship was detected between adipose tissue parameters and histopathologic features of the CRC group (P > 0.05).

CONCLUSION

We found statistically significant lower VAT and SAT volumes in patients with early-stage CRC compared with the control group. Volumetric adipose tissue measurements may be more accurate than area measurements and can easily be performed on abdominopelvic CT examination, which is the routine imaging modality for CRC patients.

Improvement of Asia-Pacific colorectal screening score and evaluation of its use combined with fecal immunochemical test

Background

The Asia-Pacific Colorectal Screening (APCS) score is effective to screen high-risk groups of advanced colorectal neoplasia (ACN) patients but needs revising and can be combined with the fecal immunochemical test (FIT). This paper aimed to improve the APCS score and evaluate its use with the FIT in stratifying the risk of ACN.

Methods

This prospective and multicenter study enrolled 955 and 1201 asymptomatic Chinese participants to form the derivation and validation set, respectively. Participants received the risk factor questionnaire, colonoscopy and FIT. Multiple logistic regression was applied, and C-statistic, sensitivity and negative predictive values (NPVs) were used to compare the screening efficiency.

Results

A modified model was developed incorporating age, body mass index (BMI), family history, diabetes, smoking and drinking as risk factors, stratifying subjects into average risk (AR) or high risk (HR). In the validation set, the HR tier group had a 3.4-fold (95% CI 1.8–6.4) increased risk for ACN. The C-statistic for the modified score was 0.69 ± 0.04, and 0.67 ± 0.04 for the original score. The sensitivity of the modified APCS score combined with FIT for screening ACN high-risk cohorts was 76.7% compared with 36.7% of FIT alone and 70.0% of the modified APCS score alone. The NPVs of the modified score combined with FIT for ACN were 98.0% compared with 97.0% of FIT alone and 97.9% of the modified APCS score alone.

Conclusions

The modified score and its use with the FIT are efficient in selecting the HR group from a Chinese asymptomatic population.

Effects of SHBG rs1799941 Polymorphism on Free Testosterone Levels and Hypogonadism Risk in Young Non-Diabetic Obese Males

Introduction: Obesity has been associated with increased risk of presenting hypogonadism. Free testosterone (FT) is the fraction of testosterone that carries out the biological function of testosterone, and is determined from total testosterone (TT) and sex-hormone binding globulin (SHBG) levels. We aimed to study the SHBG polymorphism rs1799941 in a cohort of young non-diabetic obese males to unravel the possible implication of this polymorphism in obesity-related hypogonadism. Methodology: 212 young (<45 years) non-diabetic obese (BMI ≥ 30 kg/m²) males participated in this study. Subjects were classified according to TT and FT levels in: Eugonadal (n = 55, TT > 3.5 ng/mL and FT ≥ 70 pg/mL; EuG), normal FT hypogonadism (n = 40, TT < 3.5 and FT ≥ 70 pg/mL; normal FT HG) and hypogonadism (n = 117, TT < 3.5 ng/mL and TL < 70 pg/mL; HG). The SHBG rs1799941 polymorphism (GG/GA/AA) was analyzed using the Taqman Open Array (Applied biosystem). Results: The rs1799941 frequencies were different among the groups. Higher proportion of the allele (A) was found in HG, compared to EuG and normal FT HG. Among the genotypes, the rare homozygous (AA) were found in the normal FT HG group and higher levels of serum SHBG and lower of FT were observed. The presence of the allele A was related (according to lineal regression models) to an increased of SHBG levels ((GA) β = 3.28; (AA) β = 12.45) and a decreased of FT levels ((GA) β = −9.19; (AA) β = −18.52). The presence of the allele (A) increased the risk of presenting HG compared to normal FT HG (OR = 2.54). Conclusions: The rs1799941 of the SHBG gene can partially determine the presence of obesity-related hypogonadism in young non-diabetic males and whether these subjects have normal FT HG.

Body Mass Index and Long-Term Outcomes in Patients With Colorectal Cancer

Background: The association between body mass index (BMI) and colorectal cancer is unique. There are several patient- and tumor-related factors that affect this and associations are not entirely clear. The primary aim of this study is to examine the association between BMI and survival after colorectal cancer diagnosis.

Methods: Among 26,908 Mayo Clinic patients diagnosed with colorectal cancer between 1972 and 2017, 3,799 patients had information on BMI within 6 months prior to cancer diagnosis. Multivariable Cox regression models were used to assess the differences in overall survival between BMI groups in each cancer stage, controlling for age, gender, year of diagnosis, and cancer location. The impact of change of BMI at 30, 60, and 90 days on survival afterwards were also analyzed.

Results: Among 3,799 patients included in the study, there were 29% normal weight, 2% underweight, 36% overweight, and 33% obese patients. With all stages combined together, the overall 5-years survival rates for underweight, normal weight, overweight, and obese patients were 33, 56, 60, and 65%, respectively (p < 0.001). The results show that, the difference in overall survival was not statistically significant when underweight, overweight, and obese patients were compared to normal weight patients in stage 1 and stage 2, although there was a trend that overweight patients had better survival than normal weight group in stage 2 cancer patients (HR = 0.8, p = 0.086). In stage 3 and 4 patients combined, underweight group demonstrated a significant disadvantage (HR = 1.96, p = 0.007) for overall survival compared to the normal weight group. Additionally, post-diagnosis BMI drop more than 10% from either a previous time (HR = 1.88, p = 0.002) or pre-diagnosis time (HR = 1.61, p < 0.001) was associated with worse overall survival after adjusting for baseline variables.

Conclusions: BMI is an important consideration in patients with colorectal cancer. Outcomes are stage-dependent where in some situations obesity maybe an advantage. More importantly, being underweight is a significant negative predictor of outcome. The impact of drop in BMI or weight, on survival of CRC patients, needs to be studied further since this is potentially an actionable variable and a dynamic biomarker that may help improve outcome in these patients.

Which Patient-Related Factors Determine Optimal Bowel Preparation?

PURPOSE OF REVIEW

Adequate bowel cleansing before colonoscopy is a simple concept but the high rate of inadequate or incomplete bowel cleanliness and its consequences have been the subject of many studies, guidelines, and meta-analysis. The complexity resides in all the factors surrounding preparation intake such as type and regimen of bowel preparation, diets, compliance, and also patient-related factors that all influence quality of the bowel preparation. The purpose of this review is to focus specifically on patient-related factors and their challenges. Patients with lower GI bleeding are excluded from this review.

RECENT FINDINGS

Patient factors that may be associated with a poor bowel preparation were searched for in the literature. With regard to patient's characteristics, higher age, male gender, and socio-economic status (lower income, Medicaid, and lower education) were all associated with higher rates of inadequate bowel preparation. Comorbidities such as inflammatory bowel disease (IBD), in-patients, body mass index (BMI), cirrhosis, constipation, and neurological condition as well as some pharmacotherapy were also associated with inadequate bowel preparation. Studies identifying predictive patient factors as well as those studying these patients in particular showed variability in the strength of the patient factor associations. Patients taking tricyclic antidepressant, narcotics, and those with neurological conditions were identified to have a stronger association with worse bowel cleanliness. Those can be implemented with the current recommendations of split-dosing. Identifying individual factors that can impact the quality of bowel cleanliness can be challenging. Some have been well-studied in the literature such as age, in-patient status, or constipation and others such as male gender or higher BMI have required more studies to clearly conclude on any possible association. In many studies, simple recommendations like walking 30 min during the preparation, and additional instructions or support have also been added to instructions to improve motility and compliance.

Is obesity an advantage in patients with colorectal cancer?

Obesity/higher BMI appears to be important determinants in the development of colon cancer as well as in predicting outcomes in the adjuvant setting in these patients. These associations seem to be stronger for men and tend to be 'J-shaped', with worse outcomes in both lower and upper BMI categories than in the middle categories. How this factors in the metastatic setting is less clear. A recent pooled analysis of patients with metastatic colorectal cancer receiving bevacizumab in the first-line setting observed that patients with the lowest BMI had the lowest median overall survival. An incremental BMI increase of 5 kg/m(2) led to actually a decrease in the risk of death (hazard ratio, 0.911 [95% CI, 0.879-0.944]). The observed association does not necessarily mean that obesity is an advantage for patients with metastatic colorectal cancer. More likely, it is conceivable that, in patients with metastatic colorectal cancer with a lower BMI, the effects of cancer-related cachexia may be more deleterious than the potential adverse events related to a higher BMI. In patients already diagnosed with metastatic disease, studying how body weight affects tumor biology and treatment-related decisions are important considerations.

Obesity and colorectal liver metastases: Mechanisms and management

INTRODUCTION

Colorectal cancer (CRC) is the third commonest malignancy after lung and breast cancer. The most common cause of mortality from CRC is from distant metastases. Obesity is a known risk factor for primary CRC development. However, its role in metastatic disease progression is not fully understood. The article aims to provide an overview of the role of obesity in colorectal liver metastases (CRLM). Furthermore, possible strategies to minimise this effect are discussed. An electronic search of MedLine, EMBASE, CINAHL and google scholar was performed. Relevant articles were included in the article. Obesity causes localised inflammation within the liver microenvironment which may predispose to metastases development. Furthermore, obesity causes systemic inflammation leading to release of protumourigenic growth factors. Several studies demonstrated the effects of lifestyle modification, medications, bariatric surgery and omega-3 fatty acids on steatosis within the context of liver surgery. It is currently unclear whether obesity directly leads to metastatic disease via chronic systemic inflammation or whether obesity induced steatosis provides a fertile microenvironment for metastases deposition. With a global increase in obesity useful strategies to minimise the effects of obesity on the liver include life-style modification, pre-operative dietary regimes and omega-3 fatty acids intake. Pre-operative optimisation of the patient is a key concept. Further randomised control trials are needed to guide management strategies.

Trend Analysis of Cancer Mortality and Incidence in Panama, Using Joinpoint Regression Analysis

Cancer is one of the leading causes of death worldwide and its incidence is expected to increase in the future. In Panama, cancer is also one of the leading causes of death. In 1964, a nationwide cancer registry was started and it was restructured and improved in 2012. The aim of this study is to utilize Joinpoint regression analysis to study the trends of the incidence and mortality of cancer in Panama in the last decade. Cancer mortality was estimated from the Panamanian National Institute of Census and Statistics Registry for the period 2001 to 2011. Cancer incidence was estimated from the Panamanian National Cancer Registry for the period 2000 to 2009. The Joinpoint Regression Analysis program, version 4.0.4, was used to calculate trends by age-adjusted incidence and mortality rates for selected cancers. Overall, the trend of age-adjusted cancer mortality in Panama has declined over the last 10 years (-1.12% per year). The cancers for which there was a significant increase in the trend of mortality were female breast cancer and ovarian cancer; while the highest increases in incidence were shown for breast cancer, liver cancer, and prostate cancer. Significant decrease in the trend of mortality was evidenced for the following: prostate cancer, lung and bronchus cancer, and cervical cancer; with respect to incidence, only oral and pharynx cancer in both sexes had a significant decrease. Some cancers showed no significant trends in incidence or mortality. This study reveals contrasting trends in cancer incidence and mortality in Panama in the last decade. Although Panama is considered an upper middle income nation, this study demonstrates that some cancer mortality trends, like the ones seen in cervical and lung cancer, behave similarly to the ones seen in high income countries. In contrast, other types, like breast cancer, follow a pattern seen in countries undergoing a transition to a developed economy with its associated lifestyle, nutrition, and body weight changes.

Modification in the diet can induce beneficial effects against breast cancer

The population tends to consume foods that in addition to their nutritional values can offer some benefits to their health. There are many epidemiological evidences and research studies in animal models suggesting that diet plays an important role in breast cancer prevention or progression. This review summarized some of the relevant researches about nutrition and cancer during the last years, especially in breast cancer. The analysis of probiotics and fermented products containing lactic acid bacteria in cancer prevention and/or treatment was especially discussed. It was observed that a balance of fatty acids similar to those of traditional Mediterranean diet, the consumption of fruits and vegetables, dietary fiber intake, vitamin supplementation are, along with the intake of probiotic products, the most extensively studied by the negative association to breast cancer risk. The consumption of probiotics and fermented products containing lactic acid bacteria was associated to reduce breast cancer risk in some epidemiological studies. The use of animal models showed the modulation of the host’s immune response as one of the important effects associated to the benefices observed with most probiotics. However; future assays in human are very important before the medical community can accept the addition of probiotic or fermented milks containing lactic acid bacteria as supplements for cancer patients.

Obesity and colorectal cancer: Role of adipokines in tumor initiation and progression

Obesity-associated diseases account for a large portion of public health challenges. Among obesity-related disorders, a direct and independent relationship has been ascertained for colorectal cancer (CRC). The evidence that adipocyte hypertrophy and excessive adipose tissue accumulation (mainly visceral) can promote pathogenic adipocyte and adipose tissue-related diseases, has led to formulate the concept of “adiposopathy”, defined as adipocyte and adipose tissue dysfunction that contributes to metabolic syndrome. Adipose tissue can, indeed, be regarded as an important and highly active player of the innate immune response, in which cytokine/adipokine secretion is responsible for a paracrine loop between adipocytes and macrophages, thus contributing to the systemic chronic low-grade inflammation associated with visceral obesity, which represents a favorable niche for tumor development. The adipocyte itself participates as a central mediator of this inflammatory response in obese individuals by secreting hormones, growth factors and proinflammatory cytokines, which are of particular relevance for the pathogenesis of CRC. Among adipocyte-secreted hormones, the most relevant to colorectal tumorigenesis are adiponectin, leptin, resistin and ghrelin. All these molecules have been involved in cell growth and proliferation, as well as tumor angiogenesis and it has been demonstrated that their expression changes from normal colonic mucosa to adenoma and adenocarcinoma, suggesting their involvement in multistep colorectal carcinogenesis. These findings have led to the hypothesis that an unfavorable adipokine profile, with a reduction of those with an anti-inflammatory and anti-cancerous activity, might serve as a prognostic factor in CRC patients and that adipokines or their analogues/antagonists might become useful agents in the management or chemoprevention of CRC.

Molecular mechanism of TGF-β signaling pathway in colon carcinogenesis and status of curcumin as chemopreventive strategy

Colon cancer is one of the third most common cancer in man, the second most common cancer in women worldwide, and the second leading cause of mortality in the USA. There are a number of molecular pathways that have been implicated in colon carcinogenesis, including TGF-β/Smad signaling pathway. TGF-β (transforming growth factor-beta) signaling pathway has the potential to regulate various biological processes including cell growth, differentiation, apoptosis, extracellular matrix modeling, and immune response. TGF-β signaling pathway acts as a tumor suppressor, but alterations in TGF-β signaling pathway promotes colon cancer cell growth, migration, invasion, angiogenesis, and metastasis. Here we review the role of TGF-β signaling cascade in colon carcinogenesis and multiple molecular targets of curcumin in colon carcinogenesis. Elucidation of the molecular mechanism of curcumin on TGF-β signaling pathway-induced colon carcinogenesis may ultimately lead to novel and more effective treatments for colon cancer.