Calcium intake and risk of colorectal cancer according to expression status of calcium-sensing receptor (CASR)

Genetically Determined Circulating Lactase/Phlorizin Hydrolase Concentrations and Risk of Colorectal Cancer: A Two-Sample Mendelian Randomization Study

Previous research has found that milk is associated with a decreased risk of colorectal cancer (CRC). However, it is unclear whether the milk digestion by the enzyme lactase-phlorizin hydrolase (LPH) plays a role in CRC susceptibility. Our study aims to investigate the direct causal relationship of CRC risk with LPH levels by applying a two-sample Mendelian Randomization (MR) strategy. Genetic instruments for LPH were derived from the Fenland Study, and CRC-associated summary statistics for these instruments were extracted from the FinnGen Study, PLCO Atlas Project, and Pan-UK Biobank. Primary MR analyses focused on a cis-variant (rs4988235) for LPH levels, with results integrated via meta-analysis. MR analyses using all variants were also undertaken. This analytical approach was further extended to assess CRC subtypes (colon and rectal). Meta-analysis across the three datasets illustrated an inverse association between genetically predicted LPH levels and CRC risk (OR: 0.92 [95% CI, 0.89-0.95]). Subtype analyses revealed associations of elevated LPH levels with reduced risks for both colon (OR: 0.92 [95% CI, 0.89-0.96]) and rectal cancer (OR: 0.92 [95% CI, 0.87, 0.98]). Consistency was observed across varied analytical methods and datasets. Further exploration is warranted to unveil the underlying mechanisms and validate LPH's potential role in CRC prevention.

Implication of calcium supplementations in health and diseases with special focus on colorectal cancer

Calcium is a fundamental and integrative element and helps to ensure optimal health by regulating various physiological and pathological processes. While there is substantiated evidence confirming the beneficial effects of calcium in the treatment, management, and prevention of various health conditions, including cancer, conflicting studies are imperative to acknowledge the potential negative role of calcium supplementation. The studies on calcium supplementation showed that a specific dose can help in the maintenance of good human health, and in the control of different types of diseases, including cancer. Calcium alone and when combined with vitamin D, emerges as a promising therapeutic option for efficiently managing cancer growth, when used with chemotherapy. Combination therapy is considered a more effective approach for treating advanced types of colorectal cancer. Nevertheless, several challenges drastically influence the treatment of cancer, such as individual discrepancy, drug resistance, and stage of cancer, among others. Henceforth, novel preventive, reliable therapeutic modalities are essential to control and reduce the incidence and mortality of colorectal cancer (CRC). The calcium-sensing receptor (CaSR) plays a pivotal role in calcium homeostasis, metabolism, and regulation of oncogenesis. Numerous studies have underscored the potential of CaSR, a G protein-coupled receptor, as a potential biomarker and target for colorectal cancer prevention and treatment. The multifaceted involvement of CaSR in anti-inflammatory and anti-carcinogenic processes paves the way for its utilization in the diagnosis and management of colorectal cancer. The current review highlights the important role of supplemental calcium in overall health and disease, along with the exploration of intricate mechanisms of CaSR pathways in the management and prevention of colorectal cancer.

Calcium/calcimimetic via calcium-sensing receptor ameliorates cholera toxin-induced secretory diarrhea in mice

BACKGROUND

Enterotoxins produce diarrhea through direct epithelial action and indirectly by activating the enteric nervous system. Calcium-sensing receptor (CaSR) inhibits both actions. The latter has been well documented in vitro but not in vivo. The hypothesis to be tested was that activating CaSR inhibits diarrhea in vivo.

AIM

To determine whether CaSR agonists ameliorate secretory diarrhea evoked by cholera toxin (CTX) in mice.

METHODS

CTX was given orally to C57BL/6 mice to induce diarrhea. Calcium and calcimimetic R568 were used to activate CaSR. To maximize their local intestinal actions, calcium was administered luminally via oral rehydration solution (ORS), whereas R568 was applied serosally using an intraperitoneal route. To verify that their actions resulted from the intestine, effects were also examined on Cre-lox intestine-specific CaSR knockouts. Diarrhea outcome was measured biochemically by monitoring changes in fecal Cl- or clinically by assessing stool consistency and weight loss.

RESULTS

CTX induced secretory diarrhea, as evidenced by increases in fecal Cl-, stool consistency, and weight loss following CTX exposure, but did not alter CaSR, neither in content nor in function. Accordingly, calcium and R568 were each able to ameliorate diarrhea when applied to diseased intestines. Intestinal CaSR involvement is suggested by gene knockout experiments where the anti-diarrheal actions of R568 were lost in intestinal epithelial CaSR knockouts (villinCre/Casrflox/flox) and neuronal CaSR knockouts (nestinCre/Casrflox/flox).

CONCLUSION

Treatment of acute secretory diarrheas remains a global challenge. Despite advances in diarrhea research, few have been made in the realm of diarrhea therapeutics. ORS therapy has remained the standard of care, although it does not halt the losses of intestinal fluid and ions caused by pathogens. There is no cost-effective therapeutic for diarrhea. This and other studies suggest that adding calcium to ORS or using calcimimetics to activate intestinal CaSR might represent a novel approach for treating secretory diarrheal diseases.

Calcium-sensing receptor and NF-κB pathways in TN breast cancer contribute to cancer-induced cardiomyocyte damage via activating neutrophil extracellular traps formation

Cardiovascular disorders are commonly prevalent in cancer patients, yet the mechanistic link between them remains poorly understood. Because neutrophil extracellular traps (NETs) have implications not just in cardiovascular diseases (CVD), but also in breast cancer (BC), it was hypothesized to contribute to CVD in the context of oncogenesis. We established a mouse model using nude mice to simulate liver metastasis of triple-negative BC (TNBC) through the injection of MDA-MB-231 cells. Multiple imaging and analysis techniques were employed to assess the cardiac function and structure, including echocardiography, HE staining, Masson staining, and transmission electron microscopy (TEM). MDA-MB-231 cells underwent treatment with a CaSR inhibitor, CaSR agonist, and NF-κB channel blocker. The phosphorylation of NF-κB channel protein p65 and the expression and secretion of IL-8 were assessed using qRT-PCR, Western Blot, and ELISA, respectively. In addition, MDA-MB-231 cells were co-cultured with polymorphonuclear neutrophils (PMN) under varying conditions. The co-localization of PMN extracellular myeloperoxidase (MPO) and DNA were observed by cellular immunofluorescence staining to identify the formation of NETs. Then, the cardiomyocytes were co-cultured with the above medium that contains NETs or not, respectively; the effects of NETs on cardiomyocytes apoptosis were perceived by flow cytometry. The ultrastructural changes of myocardial cells were perceived by TEM, and ELISA detected the levels of myocardial enzyme (LDH, MDA and SOD). Overall, according to our research, CaSR has been found to have a regulatory role in IL-8 secretion in MDA-MB-231 cells, as well as in the formation of NETs by PMN cells. These findings suggest CaSR-mediated stimulation in PMN can lead to increased NETs formation and subsequently to cytotoxicity in cardiomyocytes, which potentially via activation of the NF-κB signaling cascade of BC cell.

Association between dietary calcium intake and severe abdominal aorta calcification among American adults: a cross-sectional analysis of the National Health and Nutrition Examination Survey

BACKGROUND

Evidence regarding the relationship between dietary calcium intake and severe abdominal aortic calcification (AAC) is limited. Therefore, this study aimed to investigate the association between dietary calcium intake and severe AAC in American adults based on data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

The present cross-sectional study utilized data from the NHANES 2013-2014, a population-based dataset. Dietary calcium intake was assessed using two 24-h dietary recall interviews. Quantification of the AAC scores was accomplished utilizing the Kauppila score system, whereby severe AAC was defined as having an AAC score greater than 6. We used multivariable logistic regression models, a restricted cubic spline analysis, and a two-piecewise linear regression model to show the effect of calcium intake on severe AAC.

RESULTS

Out of the 2640 individuals examined, 10.9% had severe AAC. Following the adjustment for confounding variables, an independent association was discovered between an augmented intake of dietary calcium and the incidence of severe AAC. When comparing individuals in the second quartile (Q2) of dietary calcium intake with those in the lowest quartile (Q1), a decrease in the occurrence of severe AAC was observed (odds ratio: 0.66; 95% confidence interval: 0.44-0.99). Furthermore, the relationship between dietary calcium intake and severe AAC demonstrated an L-shaped pattern, with an inflection point observed at 907.259 mg/day. Subgroup analyses revealed no significant interaction effects.

CONCLUSION

The study revealed that the relationship between dietary calcium intake and severe AAC in American adults is L-shaped, with an inflection point of 907.259 mg/day. Further research is required to confirm this association.

Calcium-sensing Receptor, a Potential Biomarker Revealed by Large-scale Public Databases and Experimental Verification in Metastatic Breast Cancer

INTRODUCTION

Breast cancer (BC) is a common cancer characterized by a high molecular heterogeneity. Therefore, understanding its biological properties and developing effective treatments for patients with different molecular features is imperative. Calcium-sensing receptor (CaSR) has been implicated in several regulatory functions in various types of human cancers. However, its underlying pathological mechanism in BC progression remains elusive.

METHODS

We utilized The Cancer Genome Atlas and Gene Expression Omnibus databases to explore the function of CaSR in the metastasis of BC. Gene ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis, and Gene Set Enrichment Analysis of biological processes and cell signaling pathways revealed that CaSR could be activated or inhibited. Importantly, quantitative reverse transcriptase-polymerase chain reaction and western blotting were used to verify the gene expression of the CaSR. Wound healing and transwell assays were conducted to assess the effect of CaSR on the migration of BC cells.

RESULTS

We demonstrated that CaSR expression in metastatic BC was higher than that in non-metastatic BC. It is the first time that database information has been used to reveal the biological process and molecular mechanism of CaSR in BC. Moreover, the CaSR expression in normal breast epithelial cells was notably less compared to that in BC cells. The activation of CaSR by Cinacalcet (a CaSR agonist) significantly enhanced the migration of BC cells, whereas NPS-2143 (a CaSR antagonist) treatment dramatically inhibited these effects.

CONCLUSION AND FUTURE PERSPECTIVE

Bioinformatics techniques and experiments demonstrated the involvement of CaSR in BC metastasis. Our findings shed new light on the receptor therapy and molecular pathogenesis of BC, and emphasize the crucial function of CaSR, facilitating the metastasis of BC.

Pan-cancer analysis reveals the prognostic gene CASR suppresses tumor progression and epithelial-mesenchymal transition in renal clear cell carcinoma

Calcium-sensing receptor (CASR), primarily found in the parathyroid gland and other tissues, plays a crucial role in sensing and regulating extracellular calcium, which was also aberrantly expressed in human tumors. Nevertheless, a comprehensive analysis of CASR in pan-cancer has yet to be conducted. To gain a better understanding of CASR in pan-cancer, data profiles on CASR cancers were collected from TCGA database. The expression level, clinical significance, prognostic value, and potential mechanisms of CASR in pan-cancer were analyzed via multiple public databases. The functional assays were conducted using human kidney renal clear cell carcinoma (KIRC) cell lines, clinical samples, and nude mice. Our research revealed that the abnormal expression of CASR was found in a variety of tumors. The expression and mutation of CASR were significantly associated with tumor prognosis and stage. Pathway analyses suggested that CASR was involved in the epithelial-mesenchymal transition (EMT) progress. Besides, CASR expression was correlated with immune inhibitory genes and immunotherapy in cancers. Particularly in KIRC, we established that CASR mRNA and protein levels were downregulated in clinical samples and cell lines. Moreover, a Cox regression analysis revealed that CASR was an independent prognostic factor in both TCGA-KIRC samples and clinical samples from our center. In vitro and in vivo experiments revealed that blocking CASR with lentivirus could suppress tumor growth and invasion, and EMT progress in KIRC cells. In summary, our study provides a comprehensive bioinformatic analysis of CASR in pan-cancer, offering deeper insights into its function and the EMT mechanism in KIRC, warranting further investigation.

Targeting beta-catenin signaling for prevention of colorectal cancer - Nutraceutical, drug, and dietary options

Progressive up-regulation of β-catenin signaling is very common in the transformation of colorectal epithelium to colorectal cancer (CRC). Practical measures for opposing such signaling hence have potential for preventing or slowing such transformation. cAMP/PKA activity in colon epithelium, as stimulated by COX-2-generated prostaglandins and β2-adrenergic signaling, boosts β-catenin activity, whereas cGMP/PKG signaling has the opposite effect. Bacterial generation of short-chain fatty acids (as supported by unrefined high-carbohydrate diets, berberine, and probiotics), dietary calcium, daily aspirin, antioxidants opposing cox-2 induction, and nicotine avoidance, can suppress cAMP production in colonic epithelium, whereas cGMP can be boosted via linaclotides, PDE5 inhibitors such as sildenafil or icariin, and likely high-dose biotin. Selective activation of estrogen receptor-β by soy isoflavones, support of adequate vitamin D receptor activity with UV exposure or supplemental vitamin D, and inhibition of CK2 activity with flavanols such as quercetin, can also oppose β-catenin signaling in colorectal epithelium. Secondary bile acids, the colonic production of which can be diminished by low-fat diets and berberine, can up-regulate β-catenin activity by down-regulating farnesoid X receptor expression. Stimulation of PI3K/Akt via insulin, IGF-I, TLR4, and EGFR receptors boosts β-catenin levels via inhibition of glycogen synthase-3β; plant-based diets can down-regulate insulin and IGF-I levels, exercise training and leanness can keep insulin low, anthocyanins and their key metabolite ferulic acid have potential for opposing TLR4 signaling, and silibinin is a direct antagonist for EGFR. Partially hydrolyzed phytate can oppose growth factor-mediated down-regulation of β-catenin by inhibiting Akt activation. Multifactorial strategies for safely opposing β-catenin signaling can be complemented with measures that diminish colonic mutagenesis and DNA hypomethylation - such as avoidance of heme-rich meat and charred or processed meats, consumption of phase II-inductive foods and nutraceuticals (e.g., Crucifera), and assurance of adequate folate status.

Burden of early-onset colorectal cancer along with attributable risk factors from 1990 to 2019: a comparative study between China and other G20 countries

PURPOSE

The credible data about the burden of early-onset colorectal cancer (EOCRC) in China when compared to other countries in the group of twenty (G20) remained unavailable. We aimed to assess the burden and trends of EOCRC and attributable risk factors in China. Meanwhile, the comparison in the burden and attributable risk factors between China and other G20 countries was also evaluated.

METHODS

Data on the incidence, prevalence, mortality, disability-adjusted life years (DALYs), and attributable risk factors of EOCRC in China were obtained from Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 and compared with other G20countries. Temporal trends of age-standardized rates for incidence, prevalence, mortality, and DALYs were evaluated by estimated annual percentage change (EAPC). The autoregressive integrated moving average (ARIMA) model was used to forecast the incidence, mortality, and DALY rates of EOCRC in China from 2020 to 2029.

RESULTS

From 1990 to 2019, the age-standardized incidence rate (ASIR) and age-standardized prevalence rate (ASPR) of EOCRC in China increased with the EAPCs of 4.61 [95% confidence interval (CI): 4.45-4.77] and 5.82 (95% CI: 5.60-6.05). When compared to G20 countries, China was ranked 13^th in the ASIR in 1990 and then increased to 2^nd in 2019, second only to Japan. The ASPRs increased in all G20 countries, being highest in Saudi Arabia, followed by China and Mexico. Moreover, China had the highest age-standardized mortality rate and highest age-standardized DALY rate in 2019. In China, the five leading risk factors, for both sexes, were diet low in milk [18.54% (95% UI: 12.71-24.07)], diet low in calcium [15.06% (95% UI: 10.70-20.03)], alcohol use [12.16% (95% UI: 8.87-15.64)], smoking [9.08% (95% UI: 3.39-14.11)], and diet high in red meat [9.08% (95% UI: 3.39-14.11)] in 2019. Over the next 10 years, ASIR, ASMR, and age-standardized DALY rate of EOCRC will increase continuously in males and females.

CONCLUSION

The burden of EOCRC in China and other G20 countries is worrisome, indicating that coordinated efforts are needed to conduct high-quality researches, allocate medical resources, adjust screening guidelines, and develop effective treatment and prevention strategies in the G20 countries.

Total calcium, dairy foods and risk of colorectal cancer: a prospective cohort study of younger US women

BACKGROUND

Although colorectal cancer (CRC) incidence is declining among adults aged ≥65 years, CRC incidence in younger adults has been rising. The protective role of calcium in colorectal carcinogenesis has been well established, but evidence is lacking on whether the association varies by age at diagnosis. We investigated the association between total calcium intake and risk of overall CRC and CRC before age 55 years.

METHODS

In the Nurses' Health Study II (1991-2015), 94 205 women aged 25-42 years at baseline were included in the analysis. Diet was assessed every 4 years through validated food frequency questionnaires. Multivariable-adjusted hazard ratios (HRs) and 95% CIs for CRC were estimated using the Cox proportional hazards model.

RESULTS

We documented 349 incident CRC cases during 2 202 604 person-years of follow-up. Higher total calcium intake was associated with a reduced risk of CRC. Compared with those with <750 mg/day of total calcium intake, the HR of CRC was 0.61 (95% CI, 0.38-0.97) for those who consumed ≥1500 mg/day (P for trend = 0.01). The HR per 300 mg/day increase was 0.85 (95% CI, 0.76-0.95). There was a suggestive inverse association between total calcium intake and CRC before age 55 years (HR per 300 mg/day increase, 0.87; 95% CI, 0.75-1.00), suggesting the importance of calcium intake in the younger population.

CONCLUSIONS

In a cohort of younger women, which reflects the birth cohorts, time periods and age ranges paralleling the recent rise in CRC, higher calcium intake was associated with a decreased risk of CRC.

Astragalus Polysaccharides Alleviate Lung Adenocarcinoma Bone Metastases by Inhibiting the CaSR/PTHrP Signaling Pathway

Bone metastasis is one of the common complications of lung cancer and can lead to bone-related adverse events, such as pathological fractures, spinal cord defects, and nerve compression syndrome. As an effective medicinal component of Astragalus membranaceus, Astragalus polysaccharide (APS) has antitumor activity and alleviates osteoporosis to a certain extent. In this study, we explored the possible role and mechanism underlying APS inhibition of lung adenocarcinoma bone metastases by constructing a mouse model of lung adenocarcinoma bone metastases. First, we constructed osteoclast (OC) and osteoblast (OB) culture systems in vitro to confirm that APS affected the differentiation and function of OCs and OBs. Then, using the mouse bone metastasis model, microCT, and bone histopathology, we confirmed that APS inhibited osteolytic metastasis and tumor cell proliferation in mice, and the effect was mainly realized by inhibiting the CaSR/PTHrP signal pathway. The results showed that APS had a protective effect on lung adenocarcinoma bone metastases.

Elevation of spermine remodels immunosuppressive microenvironment through driving the modification of PD-L1 in hepatocellular carcinoma

Background

Spermine is frequently elevated in tumor tissues and body fluids of cancer patients and is critical for cancer cell proliferation, migration and invasion. However, the immune functions of spermine in hepatocellular carcinoma progression remains unknown. In the present study, we aimed to elucidate immunosuppressive role of spermine in hepatocellular carcinoma and to explore the underlying mechanism.

Methods

Whole-blood spermine concentration was measured using HPLC. Human primary HCC tissues were collected to examine the expression of CaSR, p-Akt, β-catenin, STT3A, PD-L1, and CD8. Mouse model of tumorigenesis and lung metastasis were established to evaluate the effects of spermine on hepatocellular carcinoma. Western blotting, immunofluorescence, real time PCR, digital Ca2+ imaging, and chromatin immunoprecipitation assay were used to investigate the underlying mechanisms by which spermine regulates PD-L1 expression and glycosylation in hepatocellular carcinoma cells.

Results

Blood spermine concentration in the HCC patient group was significantly higher than that in the normal population group. Spermine could facilitate tumor progression through inducing PD-L1 expression and decreasing the CD8+ T cell infiltration in HCC. Mechanistically, spermine activates calcium-sensing receptor (CaSR) to trigger Ca2+ entry and thereby promote Akt-dependent β-catenin stabilization and nuclear translocation. Nuclear β-catenin induced by spermine then activates transcriptional expression of PD-L1 and N-glycosyltransferase STT3A, while STT3A in turn increases the stability of PD-L1 through inducing PD-L1 protein N-glycosylation in HCC cells.

Conclusions

This study reveals the crucial function of spermine in establishing immune privilege by increasing the expression and N-glycosylation of PD-L1, providing a potential strategy for the treatment of hepatocellular carcinoma.

The Burden of Early-Onset Colorectal Cancer and Its Risk Factors from 1990 to 2019: A Systematic Analysis for the Global Burden of Disease Study 2019

Simple Summary

In this cross-sectional study, the global incidence, death, and DALY rates of early-onset colorectal cancer (CRC) increased from 1990 to 2019, with large variations in the regional and national levels. A low-milk or low-calcium diet and alcohol use were the leading possible risk factors in 2019. The importance of high body mass index and high fasting plasma glucose increased among both males and females from 1990 to 2019, while the importance of smoking and a low-fiber diet decreased among both sexes, but especially among females. These findings provide policymakers with an accurate quantification of the burden of early-onset CRC, and may help to identify and target high-risk individuals to mitigate the burden of early-onset CRC.

Abstract

Background: The incidence of early-onset colorectal cancer (CRC) diagnosed before age 50 has been increasing over the past decades. Hence, we examined the global, regional, and national burden of early-onset CRC and its risk factors from 1990 to 2019. Methods: Using data from the Global Burden of Disease (GBD) Study 2019, we reported the incidence, deaths, and disability-adjusted life-years (DALYs) attributable to the risk factors of early-onset CRC. All estimates were reported with 95% uncertainty intervals (UIs). Results: The global numbers of early-onset CRC for incidence, deaths, and DALYs in 2019 were 225,736 (95% UI, 207,658 to 246,756), 86,545 (80,162 to 93,431), and 4,259,922 (3,942,849 to 4,590,979), respectively. Despite large variations at the regional and national levels, the global incidence rate, death rate, and DALY rate increased from 1990 to 2019. Diets low in milk, diets low in calcium, and alcohol use were the leading risk factors in 2019. From 1990 to 2019, a high body mass index and high fasting plasma glucose ranked remarkably higher among males and females, while smoking and diets low in fiber ranked lower among both sexes, with a more profound change among females. Conclusions: Despite large variations in regional and national levels, the global incidence rate, death rate, and DALY rate increased during the past three decades. These findings may provide policymakers with an accurate quantification of the burden of early-onset CRC and targeted identification of those most at risk to mitigate the burden of early-onset CRC.

Molecular Biologic and Epidemiologic Insights for Preventability of Colorectal Cancer

The etiology of colorectal cancer (CRC) has been informed from both a molecular biology perspective, which concerns the study of the nature, timing, and consequences of mutations in driver genes, and epidemiology, which focuses on identifying risk factors for cancer. For the most part, these fields have developed independently, and it is thus important to consider them in a more integrated manner. The molecular mutational perspective has stressed the importance of mutations due to replication of adult stem cells, and the molecular fingerprint of most CRCs does not suggest the importance of direct carcinogens. Epidemiology has identified numerous modifiable risk factors that account for most CRCs, most of which are not direct mutagens. The distribution of CRCs across the large bowel is not uniform, which is possibly caused by regional differences in the microbiota. Some risk factors are likely to act through or interact with the microbiota. The mutational perspective informs when risk factors may begin to operate in life and when they may cease to operate. Evidence from the mutational model and epidemiology supports that CRC risk factors begin early in life and may contribute to the risk of early-onset CRC. Later in carcinogenesis, there may be a "point of no return" when sufficient mutations have accumulated, and some risk factors do not affect cancer risk. This period may be at least 5-15 years for some risk factors. A more precise knowledge of timing of risk factor to cancer is required to inform preventive efforts.

Vitamin D and Multiple Health Outcomes: An Umbrella Review of Observational Studies, Randomized Controlled Trials, and Mendelian Randomization Studies

Observational studies, randomized controlled trials (RCTs), and Mendelian randomization (MR) studies have yielded inconsistent results on the associations of vitamin D concentrations with multiple health outcomes. In the present umbrella review we aimed to evaluate the effects of low vitamin D concentrations and vitamin D supplementation on multiple health outcomes. We summarized current evidence obtained from meta-analyses of observational studies that examined associations between vitamin D concentrations and multiple health outcomes, meta-analyses of RCTs that investigated the effect of vitamin D supplementation on multiple health outcomes, and MR studies that explored the causal associations of vitamin D concentrations with various diseases (international prospective register of systematic reviews PROSPERO registration number CRD42018091434). A total of 296 meta-analyses of observational studies comprising 111 unique outcomes, 139 meta-analyses of RCTs comprising 46 unique outcomes, and 73 MR studies comprising 43 unique outcomes were included in the present umbrella review. Twenty-eight disease outcomes were identified by both meta-analyses of observational studies and MR studies. Seventeen of these reported disease outcomes had consistent results, demonstrating that lower concentrations of vitamin D were associated with a higher risk for all-cause mortality, Alzheimer's disease, hypertension, schizophrenia, and type 2 diabetes. The combinations of consistent evidence obtained by meta-analyses of observational studies and MR studies together with meta-analyses of RCTs showed that vitamin D supplementation was associated with a decreased risk for all-cause mortality but not associated with the risk for Alzheimer's disease, hypertension, schizophrenia, or type 2 diabetes. The results indicated that vitamin D supplementation is a promising strategy with long-term preventive effects on multiple chronic diseases and thus has the potential to decrease all-cause mortality. However, the current vitamin D supplementation strategy might not be an efficient intervention approach for these diseases, suggesting that new strategies are highly needed to improve the intervention outcomes.

Calcium intake, levels and supplementation and effect modification by genetic variation of calcium homeostasis on the risk of colorectal cancer: the Rotterdam study

OBJECTIVES

Previous studies showed that high calcium intake may be associated with the reduced colorectal cancer (CRC) risk, but results were inconclusive. In this study, we evaluated whether calcium intake from diet and supplements, as well as the calcium levels itself, were associated with the CRC risk in middle-aged and older individuals. Also, we evaluated whether these associations were modified by genetic variation of calcium homeostasis.

DESIGN

This study was embedded in the Rotterdam study, a prospective cohort study among adults aged 55 years and older without CRC at baseline, from the Ommoord district of Rotterdam, The Netherlands (N = 10 941). Effect modification by a predefined polygenetic risk score (PRS) from seven loci known to be associated with calcium concentrations, was evaluated.

RESULTS

The incidence rate of CRC in the study population was 2.9 per 1000 person-years. Relative to the recommended dietary calcium intake, only higher than the recommended dietary calcium intake (≥1485 mg/day) was associated with a reduced risk of CRC [hazard ratio (HR), 0.66; 95% confidence interval (CI), 0.44-1.00]. No significant associations were found for calcium supplementation and only in the subgroup analysis, albumin-adjusted calcium levels were associated with an increased risk of CRC (HR = 1.11; 95% CI, 1.00-1.23). PRS showed effect modification in the association between calcium intake and CRC (P for interaction = 0.08). After stratification of PRS into low, intermediate and high, we found a lower CRC risk for low-weighted PRS per increase in calcium intake.

CONCLUSION

There is no consistent association between calcium indices on CRC. However, the association between calcium intake and CRC may be modified by genetic variation associated with serum calcium concentrations that deserves further replication in other studies with different population.

Role of the calcium-sensing receptor (CaSR) in cancer metastasis to bone: Identifying a potential therapeutic target

Cancer is a major cause of morbidity and mortality worldwide due to its ability to evade immune surveillance and metastasize from its origin to a secondary point of contact. Though several treatment techniques have been developed to suppress or manage cancer spread, a strategy for total control over the disease continues to evade researchers. In considering ways to control or prevent cancer from metastasizing to the bone, we analyze the impact of the calcium-sensing receptor (CaSR), whose primary role is to maintain calcium (Ca²⁺) homeostasis in cellular and systemic physiological processes. CaSR is a pleiotropic receptor capable of enhancing the proliferation of some cancers such as breast, lung, prostate and kidney cancers at its primary site(s) and stimulating bone metastasis, while exerting a suppressive effect in others such as colon cancer. The activity of CaSR not only increases cancer cell proliferation, migration and suppression of apoptosis in the organs indicated, but also increases the secretion of parathyroid hormone-related protein (PTHrP) and epiregulin, which induce osteolytic activity and osteoblastic suppression. In addition, released cytokines and Ca²⁺ from bone resorption are critical factors that further promote cancer proliferation. In this review, we seek to highlight previous viewpoints on CaSR, discuss its role in a new context, and consider its potential clinical application in cancer treatment.

Genetically proxied milk consumption and risk of colorectal, bladder, breast, and prostate cancer: a two-sample Mendelian randomization study

BACKGROUND

Observational studies have shown that milk consumption is inversely associated with colorectal, bladder, and breast cancer risk, but positively associated with prostate cancer. However, whether the associations reflect causality remains debatable. We investigated the potential causal associations of milk consumption with the risk of colorectal, bladder, breast, and prostate cancer using a genetic variant near the LCT gene as proxy for milk consumption.

METHODS

We obtained genetic association estimates for cancer from the UK Biobank (n = 367,643 women and men), FinnGen consortium (n = 135,638 women and men), Breast Cancer Association Consortium (n = 228,951 women), and Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome consortium (n = 140,254 men). Milk consumption was proxied by a genetic variant (rs4988235 or rs182549) upstream of the gene encoding lactase, which catalyzes the breakdown of lactose.

RESULTS

Genetically proxied milk consumption was associated with a reduced risk of colorectal cancer. The odds ratio (OR) for each additional milk intake increasing allele was 0.95 (95% confidence interval [CI] 0.91-0.99; P = 0.009). There was no overall association of genetically predicted milk consumption with bladder (OR 0.99; 95% CI 0.94-1.05; P = 0.836), breast (OR 1.01; 95% CI 1.00-1.02; P = 0.113), and prostate cancer (OR 1.01; 95% CI 0.99-1.02; P = 0.389), but a positive association with prostate cancer was observed in the FinnGen consortium (OR 1.07; 95% CI 1.01-1.13; P = 0.026).

CONCLUSIONS

Our findings strengthen the evidence for a protective role of milk consumption on colorectal cancer risk. There was no or limited evidence that milk consumption affects the risk of bladder, breast, and prostate cancer.

CASR rs1801725 polymorphism is associated with the risk and prognosis of colorectal cancer: A case-control study

BACKGROUND

The extracellular calcium-sensing receptor (CASR) controls body calcium homeostasis. Increased levels of calcium are associated with protecting against colorectal cancer (CRC). This study aimed to determine the relationship between CASR gene rs1801725 polymorphism and CRC risk and prognosis.

METHODS

We conducted a hospital-based case-control study and a meta-analysis to evaluate the association of CASR gene rs1801725 polymorphism with CRC susceptibility.

RESULTS

This study proved that CASR rs1801725 polymorphism was associated with a higher risk to develop CRC (TT vs GG: OR 1.92, 95% CI [1.03-3.59], P = .042; T vs G: OR 1.30, 95% CI [1.03-1.64], P = .030). Subgroup analysis showed that this polymorphism increased the risk of CRC among smokers, and those aged ≥60 years (TT vs GG: OR 3.37, 95% CI [1.12-10.14], P = .034). We also found that this polymorphism was associated with the tumor size, TNM stage, and lymph node metastasis of CRC (GT vs GG: OR 2.03, 95% CI [1.32-3.10], P = .001). In addition, CASR gene rs1801725 polymorphism correlated with the survival of CRC patients. Further meta-analysis also obtained a significant association between this SNP and CRC risk (TT + GT vs GG: OR 1.28, 95% CI [1.01, 1.63], P = .041). Subgroup analyses by ethnicity observed a link between rs1801725 polymorphism and CRC risk in Asians, but not in Caucasians and mixed populations.

CONCLUSION

In conclusion, this case-control study and meta-analysis showed that CASR rs1801725 polymorphism increased the risk of CRC. Further studies from other races are urgently needed.

Vitamin D Effects on Cell Differentiation and Stemness in Cancer

Vitamin D₃ is the precursor of 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), a pleiotropic hormone that is a major regulator of the human genome. 1,25(OH)₂D₃ modulates the phenotype and physiology of many cell types by controlling the expression of hundreds of genes in a tissue- and cell-specific fashion. Vitamin D deficiency is common among cancer patients and numerous studies have reported that 1,25(OH)₂D₃ promotes the differentiation of a wide panel of cultured carcinoma cells, frequently associated with a reduction in cell proliferation and survival. A major mechanism of this action is inhibition of the epithelial–mesenchymal transition, which in turn is largely based on antagonism of the Wnt/β-catenin, TGF-β and EGF signaling pathways. In addition, 1,25(OH)₂D₃ controls the gene expression profile and phenotype of cancer-associated fibroblasts (CAFs), which are important players in the tumorigenic process. Moreover, recent data suggest a regulatory role of 1,25(OH)₂D₃ in the biology of normal and cancer stem cells (CSCs). Here, we revise the current knowledge of the molecular and genetic basis of the regulation by 1,25(OH)₂D₃ of the differentiation and stemness of human carcinoma cells, CAFs and CSCs. These effects support a homeostatic non-cytotoxic anticancer action of 1,25(OH)₂D₃ based on reprogramming of the phenotype of several cell types.

Meat intake and risk of hepatocellular carcinoma in two large US prospective cohorts of women and men

BACKGROUND

Epidemiological evidence on the associations between meat intake and risk of hepatocellular carcinoma (HCC) was limited and inconsistent.

METHODS

We prospectively examined the association between consumption of meats and meat mutagens with HCC risk using data from the Nurses' Health Study and the Health Professionals Follow-up Study. Cox proportional-hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) after adjusting for known liver-cancer risk factors.

RESULTS

During up to 32 years of follow-up, we documented 163 incident HCC cases. The HRs of HCC for the highest vs the lowest tertile intake levels were 1.84 (95% CI: 1.16-2.92, Ptrend = 0.04) for processed red meats and 0.61 (95% CI: 0.40-0.91, Ptrend = 0.02) for total white meats. There was a null association between unprocessed red meats and HCC risk (HR = 1.06, 95% CI: 0.68-1.63, Ptrend = 0.85). We found both poultry (HR = 0.60, 95% CI: 0.40-0.90, Ptrend = 0.01) and fish (HR = 0.70, 95% CI: 0.47-1.05, Ptrend = 0.10) were inversely associated with HCC risk. The HR for HCC risk was 0.79 (95% CI: 0.61-1.02) when 1 standard deviation of processed red meats was substituted with an equivalent amount of poultry or fish intake. We also found a suggestive positive association of intake of meat-derived mutagenicity or heterocyclic amines with risk of HCC.

CONCLUSIONS

Processed red meat intake might be associated with higher, whereas poultry or possibly fish intake might be associated with lower, risk of HCC. Replacing processed red meat with poultry or fish might be associated with reduced HCC risk.

International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function

The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.

Calcium Sensing Receptor Inhibits Growth of Human Lung Adenocarcinoma Possibly via the GSK3β/Cyclin D1 Pathway

The effect of calcium sensing receptor (CaSR) on tumor cell proliferation has been studied in several human cancers, and great discrepancies were found in different tumors. However, the role of CaSR in lung adenocarcinomas (LUADs) is not clear. Therefore, we investigated the function of CaSR on regulating the growth of human LUAD and its possible mechanism. The expression of CaSR protein and its relationship with pathological parameters were examined in paraffin sections from 51 LUAD patients, by immunohistochemistry. The results showed that CasR expression was negatively correlated with the Ki-67 index as well as the grade of malignancy in LUAD. Further, CaSR demonstrated an in vitro inhibitory effect on the proliferation of human LUAD A549 cells by regulating CaSR activity with agonist cinacalcet, antagonist NPS2143, or shRNA-CaSR transfection. Tumor xenograft models also verified the in vivo proliferation-inhibiting role of CaSR by subcutaneous injecting A549 cells into nude mice with or without changes of CaSR activity. Molecularly, Western blotting showed that CaSR positively regulated the activity of glycogen synthase kinase 3β (GSK3β), followed by the downregulation of Cyclin D1. We used the dominant negative mutant and the constitutively active mutant plasmid of GSK3β to alter GSK3β activity. Our functional experiments showed that the proliferation-inhibition of CaSR was suppressed by the inactivation of GSK3β and enhanced by the activation of GSK3β. These results suggested that CaSR played a proliferation-inhibiting role in LUAD, at least partially by regulating the GSK3β/Cyclin D1 pathway.

Loss of RDM1 enhances hepatocellular carcinoma progression via p53 and Ras/Raf/ERK pathways

Hepatocellular carcinoma (HCC), with its ineffective therapeutic options and poor prognosis, represents a global threat. In the present study, we show that RAD52 motif 1 (RDM1), a key regulator of DNA double‐strand break repair and recombination, is downregulated in HCC tissues and suppresses tumor growth. In clinical HCC samples, low expression of RDM1 correlates with larger tumor size, poor tumor differentiation, and unfavorable survival. In vitro and in vivo data demonstrate that knockdown of RDM1 increases HCC cell proliferation, colony formation, and cell population at G2/M phase, whereas RDM1 overexpression results in the opposite phenotypes. Mechanistically, RDM1 binds to the tumor suppressor p53 and enhances its protein stability. In the presence of p53, RDM1 suppresses the phosphorylation of Raf and ERK. Overexpression of p53 or treatment with ERK inhibitor significantly abolishes cell proliferation induced by the depletion of RDM1. In addition, overexpression of methyltransferase‐like 3 markedly induces N6‐methyladenosine modification of RDM1 mRNA and represses its expression. Taken together, our study indicates that RDM1 functions as a tumor suppressor and may be a potential prognostic and therapeutic factor for HCC.

The association of aberrant expression of NLRP3 and p-S6K1 in colorectal cancer

Colorectal carcinoma (CRC) is one of the most common malignancies worldwide, and except for surgery, treatments effects are limited. Recently, NLRP3 has been reported as an activator in the tumorigenesis of CRC. However, the function and mechanism of NLRP3 in CRC remains elusive. In this study, we revealed that NLRP3 was elevated in CRC tissues and related to clinical factors, such as lymph node invasion and tumor-node-metastasis (TNM) stage. Moreover, NLRP3-positive patients had a poor prognosis. Furthermore, univariate and multivariate analysis revealed that NLRP3 expression was an independent prognostic factor for the survival of CRC patients. We investigated whether NLRP3 linked with the mTOR-S6K1 pathway. The expression of p-S6K1 was upregulated in CRC tissues and NLRP3 expression level was positively associated with the p-S6K1 level. Thus, targeting NLRP3 may be promising for targeted therapy of CRC, especially for mTORC1-targeted resistant patients.

Dietary Intake of Branched-Chain Amino Acids and Risk of Colorectal Cancer

Branched-chain amino acids (BCAA) are essential amino acids, and emerging evidence suggests that BCAAs may mediate pathways related to cancer progression, possibly due to their involvement in insulin metabolism. We investigated the association between dietary intake of BCAAs with colorectal cancer risk in three prospective cohorts: the Nurses' Health Study I [(NHS), number of participants (n) at baseline = 77,017], NHS II (n = 92,984), and the Health Professionals Follow-up Study [(HPFS) n = 47,255]. Validated food frequency questionnaires were administered every 4 years and follow-up questionnaires on lifestyle biennially. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional hazards regression models. Pooled HRs were obtained using random effect models. After up to 28 years of follow-up, 1,660 cases were observed in NHS, 306 in NHS II, and 1,343 in HPFS. In multivariable adjusted models, we observed a weak inverse association between BCAA intake and colorectal cancer [highest vs. lowest quintile, pooled HR including all three cohorts (95% CI): 0.89 (0.80-1.00), P _trend = 0.06, HR per standard deviation (SD) increment 0.95 (0.92-0.99)]. However, after including dairy calcium to the models, BCAA intake was no longer associated with risk of colorectal cancer [HR 0.96 (0.85-1.08), P _trend = 0.50, HR per SD increment 0.97 (0.93-1.01)]. We did not find evidence that higher dietary BCAA intake is associated with higher risk of colorectal cancer. As this is the first prospective study to examine the association between BCAA intake and colorectal cancer, our findings warrant investigation in other cohorts.

Identification of Key Biomarkers and Potential Molecular Mechanisms in Renal Cell Carcinoma by Bioinformatics Analysis

Renal cell carcinoma (RCC) is the most common form of kidney cancer, caused by renal epithelial cells. RCC remains to be a challenging public health problem worldwide. Metastases that are resistant to radiotherapy and chemotherapy are the major cause of death from cancer. However, the underlying molecular mechanism regulating the metastasis of RCC is poorly known. Publicly available databases of RCC were obtained from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified using GEO2R analysis, whereas the Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed by Gene Set Enrichment Analysis (GSEA) and Metascape. Protein-protein interaction (PPI) network of DEGs was analyzed by STRING online database, and Cytoscape software was used for visualizing PPI network. Survival analysis of hub genes was conducted using GEPIA online database. The expression levels of hub genes were investigated from The Human Protein Atlas online database and GEPIA online database. Finally, the comparative toxicogenomics database (CTD; http://ctdbase.org) was used to identify hub genes associated with tumor or metastasis. We identified 229 DEGs comprising 135 downregulated genes and 94 upregulated genes. Functional analysis revealed that these DEGs were associates with cell recognition, regulation of immune, negative regulation of adaptive immune response, and other functions. And these DEGs mainly related to P53 signaling pathway, cytokine-cytokine receptor interaction, Natural killer cell mediated cytotoxicity, and other pathways are involved. Ten genes were identified as hub genes through module analyses in the PPI network. Finally, survival analysis of 10 hub genes was conducted, which showed that the MMP2 (matrix metallo peptidase 2), DCN, COL4A1, CASR (calcium sensing receptor), GPR4 (G protein-coupled receptor 4), UTS2 (urotensin 2), and LDLR (low density lipoprotein receptor) genes were significant for survival. In this study, the DEGs between RCC and metastatic RCC were analyzed, which assist us in systematically understanding the pathogeny underlying metastasis of RCC. The MMP2, DCN, COL4A1, CASR, GPR4, UTS2, and LDLR genes might be used as potential targets to improve diagnosis and immunotherapy biomarkers for RCC.

Calcium-induced differentiation in normal human colonoid cultures: Cell-cell / cell-matrix adhesion, barrier formation and tissue integrity

Background and aims

The goal of the study was to assess calcium alone and Aquamin, a multi-mineral natural product that contains magnesium and detectable levels of 72 trace elements in addition to calcium, for capacity to affect growth and differentiation in colonoid cultures derived from histologically-normal human colon tissue.

Methods

Colonoid cultures were maintained in a low-calcium (0.25 mM) medium or in medium supplemented with an amount of calcium (1.5–3.0 mM), either from calcium alone or Aquamin for a period of two weeks. This was shown in a previous study to induce differentiation in colonoids derived from large adenomas. Changes in growth, morphological features and protein expression profile were assessed at the end of the incubation period using a combination of phase-contrast and scanning electron microscopy, histology and immunohistology, proteomic assessment and transmission electron microscopy.

Results

Unlike the previously-studied tumor-derived colonoids (which remained un-differentiated in the absence of calcium-supplementation), normal tissue colonoids underwent differentiation as indicated by gross and microscopic appearance, a low proliferative index and high-level expression of cytokeratin 20 in the absence of intervention (i.e., in control condition). Only modest additional changes were seen in these parameters with either calcium alone or Aquamin (providing up to 3.0 mM calcium). In spite of this, proteomic analysis and immunohistochemistry revealed that both interventions induced strong up-regulation of proteins that promote cell-cell and cell-matrix adhesive functions, barrier formation and tissue integrity. Transmission electron microscopy revealed an increase in desmosomes in response to intervention.

Conclusions

These findings demonstrate that colonoids derived from histologically normal human tissue can undergo differentiation in the presence of a low ambient calcium concentration. However, higher calcium levels induce elaboration of proteins that promote cell-cell and cell-matrix adhesion. These changes could lead to improved barrier function and improved colon tissue health.

Calcium intake and colon cancer risk subtypes by tumor molecular characteristics

BACKGROUND

A preventive potential of high calcium intake against colorectal cancer has been indicated for distal colon cancer, which is inversely associated with high-level CpG island methylator phenotype (CIMP), high-level microsatellite instability (MSI), and BRAF and PIK3CA mutations. In addition, BRAF mutation is strongly inversely correlated with KRAS mutation. We hypothesized that the association between calcium intake and colon cancer risk might vary by these molecular features.

METHODS

We prospectively followed 88,506 women from the Nurses' Health Study and 47,733 men from the Health Professionals Follow-up Study for up to 30 years. Duplication-method Cox proportional cause-specific hazards regression was used to estimate multivariable hazard ratios (HRs), and 95% confidence intervals (95% CIs) for the associations between calcium intake and the risk of colon cancer subtypes. By Bonferroni correction, the α-level was adjusted to 0.01.

RESULTS

Based on 853 colon cancer cases, the inverse association between dietary calcium intake and colon cancer risk differed by CIMP status (p_{heterogeneity} = 0.01). Per each 300 mg/day increase in intake, multivariable HRs were 0.84 (95% CI 0.76-0.94) for CIMP-negative/low and 1.12 (95% CI 0.93-1.34) for CIMP-high. Similar differential associations were suggested for MSI subtypes (p_{heterogeneity} = 0.02), with the corresponding HR being 0.86 (95% CI 0.77-0.95) for non-MSI-high and 1.10 (95% CI 0.92-1.32) for MSI-high. No differential associations were observed by BRAF, KRAS, or PIK3CA mutations.

CONCLUSION

The inverse association between dietary calcium intake and colon cancer risk may be specific to CIMP-negative/low and possibly non-MSI-high subtypes.

Calcium Intake and Risk of Colorectal Cancer According to Tumor-infiltrating T Cells

Calcium intake has been associated with a lower risk of colorectal cancer. Calcium signaling may enhance T-cell proliferation and differentiation, and contribute to T-cell-mediated antitumor immunity. In this prospective cohort study, we investigated the association between calcium intake and colorectal cancer risk according to tumor immunity status to provide additional insights into the role of calcium in colorectal carcinogenesis. The densities of tumor-infiltrating T-cell subsets [CD3⁺, CD8⁺ , CD45RO (PTPRC) ⁺ , or FOXP3⁺ cell] were assessed using IHC and computer-assisted image analysis in 736 cancer cases that developed among 136,249 individuals in two cohorts. HRs and 95% confidence intervals (CI) were calculated using Cox proportional hazards regression. Total calcium intake was associated with a multivariable HR of 0.55 (comparing ≥1,200 vs. <600 mg/day; 95% CI, 0.36-0.84; P _trend = 0.002) for CD8⁺ T-cell-low but not for CD8⁺ T-cell-high tumors (HR = 1.02; 95% CI, 0.67-1.55; P _trend = 0.47). Similarly, the corresponding HRs (95% CIs) for calcium for low versus high T-cell-infiltrated tumors were 0.63 (0.42-0.94; P _trend = 0.01) and 0.89 (0.58-1.35; P _trend = 0.20) for CD3⁺ ; 0.58 (0.39-0.87; P _trend = 0.006) and 1.04 (0.69-1.58; P _trend = 0.54) for CD45RO⁺ ; and 0.56 (0.36-0.85; P _trend = 0.006) and 1.10 (0.72-1.67; P _trend = 0.47) for FOXP3⁺ , although the differences by subtypes defined by T-cell density were not statistically significant. These potential differential associations generally appeared consistent regardless of sex, source of calcium intake, tumor location, and tumor microsatellite instability status. Our findings suggest a possible role of calcium in cancer immunoprevention via modulation of T-cell function.

Calcium Intake and Survival after Colorectal Cancer Diagnosis

PURPOSE

Although evidence suggests an inverse association between calcium intake and colorectal cancer incidence, the influence of calcium on survival after colorectal cancer diagnosis remains unclear.Experimental Design: We prospectively assessed the association of postdiagnostic calcium intake with colorectal cancer-specific and overall mortality among 1,660 nonmetastatic colorectal cancer patients within the Nurses' Health Study and the Health Professionals Follow-up Study. Patients completed a validated food frequency questionnaire between 6 months and 4 years after diagnosis and were followed up for death. Multivariable hazard ratios (HRs) and 95% confidence intervals (95% CI) were calculated using Cox proportional hazards regression.

RESULTS

Comparing the highest with the lowest quartile intake of postdiagnostic total calcium, the multivariable HRs were 0.56 (95% CI, 0.32-0.96; P _trend = 0.04) for colorectal cancer-specific mortality and 0.80 (95% CI, 0.59-1.09; P _trend = 0.11) for all-cause mortality. Postdiagnostic supplemental calcium intake was also inversely associated with colorectal cancer-specific mortality (HR, 0.67; 95% CI, 0.42-1.06; P _trend = 0.047) and all-cause mortality (HR, 0.71; 95% CI, 0.54-0.94; P _trend = 0.008), although these inverse associations were primarily observed in women. In addition, calcium from diet or dairy sources was associated with lower risk in men.

CONCLUSIONS

Higher calcium intake after the diagnosis may be associated with a lower risk of death among patients with colorectal cancer. If confirmed, these findings may provide support for the nutritional recommendations of maintaining sufficient calcium intake among colorectal cancer survivors.

The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases

The Ca²⁺-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca²⁺ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca²⁺ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.

Calcium-sensing receptor in colorectal inflammation and cancer: Current insights and future perspectives

The extracellular calcium-sensing receptor (CaSR) is best known for its action in the parathyroid gland and kidneys where it controls body calcium homeostasis. However, the CaSR has different roles in the gastrointestinal tract, where it is ubiquitously expressed. In the colon, the CaSR is involved in controlling multiple mechanisms, including fluid transport, inflammation, cell proliferation and differentiation. Although the expression pattern and functions of the CaSR in the colonic microenvironment are far from being completely understood, evidence has been accumulating that the CaSR might play a protective role against both colonic inflammation and colorectal cancer. For example, CaSR agonists such as dipeptides have been suggested to reduce colonic inflammation, while dietary calcium was shown to reduce the risk of colorectal cancer. CaSR expression is lost in colonic malignancies, indicating that the CaSR is a biomarker for colonic cancer progression. This dual anti-inflammatory and anti-tumourigenic role of the CaSR makes it especially interesting in colitis-associated colorectal cancer. In this review, we describe the clinical and experimental evidence for the role of the CaSR in colonic inflammation and colorectal cancer, the intracellular signalling pathways which are putatively involved in these actions, and the possibilities to exploit these actions of the CaSR for future therapies of colonic inflammation and cancer.

Important roles of the Ca2+-sensing receptor in vascular health and disease

Ca²⁺-sensing receptor (CaSR), a member of G protein-coupled receptor family, is widely expressed in the vascular system, including perivascular neurons, vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs). When stimulated, CaSR can further increase the cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt) in two ways: intracellular Ca²⁺ release from endo/sarcoplasmic reticulum (ER/SR) and extracellular Ca²⁺ entry through Ca²⁺-permeable cation channels. In endothelium, increased Ca²⁺ subsequently activate nitric oxide synthase (NOS) and intermediate conductance Ca²⁺-activated K⁺ channels (IKCa), resulting in vasodilation through NOS-mediated NO release or membrane hyperpolarization. In VSMCs, CaSR-induced intracellular Ca²⁺ increase causes blood vessel constriction. CaSR activation predominantly induces vasorelaxation of whole vascular tissues through VECs-dependent mechanisms; however, CaSR-induced Ca²⁺ signaling in VSMCs may play a braking role in CaSR-mediated vasorelaxation. Emerging evidence reveals the importance of CaSR in the regulation of vascular tone and blood pressure. Here, we summarized recent advances in CaSR-mediated vascular reaction and the underlying mechanisms in different species, including humans. In addition, several studies have demonstrated that CaSR dysfunction may be associated with some fatal vascular diseases, such as pulmonary arterial hypertension, primary hypertension, diabetes, acute myocardial infarction and vascular calcification. With the advance of studies on CaSR in vascular health and disease, it is expected positive modulators or negative modulators of CaSR used for the treatment of specific diseases may be promising therapeutic options for the prevention and/or treatment of vascular diseases.

Calcium-Induced Differentiation of Human Colon Adenomas in Colonoid Culture: Calcium Alone versus Calcium with Additional Trace Elements

Previous murine studies have demonstrated that dietary Aquamin, a calcium-rich, multi-mineral natural product, suppressed colon polyp formation and transition to invasive tumors more effectively than calcium alone when provided over the lifespan of the animals. In the current study, we compared calcium alone to Aquamin for modulation of growth and differentiation in human colon adenomas in colonoid culture. Colonoids established from normal colonic tissue were examined in parallel. Both calcium alone at 1.5 mmol/L and Aquamin (provided at 1.5 mmol/L calcium) fostered differentiation in the adenoma colonoid cultures as compared with control (calcium at 0.15 mmol/L). When Aquamin was provided at an amount delivering 0.15 mmol/L calcium, adenoma differentiation also occurred, but was not as complete. Characteristic of colonoids undergoing differentiation was a reduction in the number of small, highly proliferative buds and their replacement by fewer but larger buds with smoother surface. Proliferation marker (Ki67) expression was reduced and markers of differentiation (CK20 and occludin) were increased along with E-cadherin translocalization to the cell surface. Additional proteins associated with differentiation/growth control [including histone-1 family members, certain keratins, NF2 (merlin), olfactomedin-4 and metallothioneins] were altered as assessed by proteomics. Immunohistologic expression of NF2 was higher with Aquamin as compared with calcium at either concentration. These findings support the conclusions that (i) calcium (1.5 mmol/L) has the capacity to modulate growth and differentiation in large human colon adenomas and (ii) Aquamin delivering 0.15 mmol/L calcium has effects on proliferation and differentiation not observed when calcium is used alone at this concentration. Cancer Prev Res; 11(7); 413-28. ©2018 AACR.

Functions and Signaling Pathways of Amino Acids in Intestinal Inflammation

Intestine is always exposed to external environment and intestinal microorganism; thus it is more sensitive to dysfunction and dysbiosis, leading to intestinal inflammation, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and diarrhea. An increasing number of studies indicate that dietary amino acids play significant roles in preventing and treating intestinal inflammation. The review aims to summarize the functions and signaling mechanisms of amino acids in intestinal inflammation. Amino acids, including essential amino acids (EAAs), conditionally essential amino acids (CEAAs), and nonessential amino acids (NEAAs), improve the functions of intestinal barrier and expressions of anti-inflammatory cytokines and tight junction proteins but decrease oxidative stress and the apoptosis of enterocytes as well as the expressions of proinflammatory cytokines in the intestinal inflammation. The functions of amino acids are associated with various signaling pathways, including mechanistic target of rapamycin (mTOR), inducible nitric oxide synthase (iNOS), calcium-sensing receptor (CaSR), nuclear factor-kappa-B (NF-κB), mitogen-activated protein kinase (MAPK), nuclear erythroid-related factor 2 (Nrf2), general controlled nonrepressed kinase 2 (GCN2), and angiotensin-converting enzyme 2 (ACE2).