Blood magnesium, and the interaction with calcium, on the risk of high-grade prostate cancer

Calcium signalling pathways in prostate cancer initiation and progression

Cancer cells proliferate, differentiate and migrate by repurposing physiological signalling mechanisms. In particular, altered calcium signalling is emerging as one of the most widespread adaptations in cancer cells. Remodelling of calcium signalling promotes the development of several malignancies, including prostate cancer. Gene expression data from in vitro, in vivo and bioinformatics studies using patient samples and xenografts have shown considerable changes in the expression of various components of the calcium signalling toolkit during the development of prostate cancer. Moreover, preclinical and clinical evidence suggests that altered calcium signalling is a crucial component of the molecular re-programming that drives prostate cancer progression. Evidence points to calcium signalling re-modelling, commonly involving crosstalk between calcium and other cellular signalling pathways, underpinning the onset and temporal progression of this disease. Discrete alterations in calcium signalling have been implicated in hormone-sensitive, castration-resistant and aggressive variant forms of prostate cancer. Hence, modulation of calcium signals and downstream effector molecules is a plausible therapeutic strategy for both early and late stages of prostate cancer. Based on this premise, clinical trials have been undertaken to establish the feasibility of targeting calcium signalling specifically for prostate cancer.

Association between a Calcium-to-Magnesium Ratio and Osteoporosis among Puerto Rican Adults

BACKGROUND

The ratio of calcium-to-magnesium intake (Ca:Mg) may be important for bone due to their competitive absorption. The Ca:Mg ratio has been related to health outcomes, but few studies have related it to bone.

OBJECTIVES

The purpose of this analysis was to examine associations between the Ca:Mg intake with bone mineral density (BMD) and osteoporosis among Puerto Rican adults.

METHODS

Adults, aged 47-79 y, from the Boston Puerto Rican Osteoporosis Study, with complete BMD and dietary data (n = 955) were included. BMD was assessed with dual-energy X-ray absorptiometry and diet by a food frequency questionnaire. Calcium and magnesium intakes from food were energy adjusted, and the Ca:Mg was calculated. Adjusted linear and logistic regression models were utilized for testing associations between Ca:Mg and bone outcomes.

RESULTS

Calcium intake was greater in the highest compared with lowest tertile, whereas magnesium intake was similar across tertiles. Mean BMD at hip sites was higher in the middle, compared with the lowest, tertile. Higher odds of osteoporosis were observed for the highest and lowest tertiles, compared with the middle tertile, after adjustment (T3 compared with T2 OR: 2.79; 95% CI: 1.47, 5.3; T1 compared with T2 OR: 2.01; 95% CI: 1.03, 3.92). Repeated analyses without supplement users (n = 432) led to stronger differences and ORs, but lost significance for some comparisons.

CONCLUSIONS

Dietary calcium and magnesium are important for bone, perhaps not independently. The Ca:Mg intake ratio appeared most protective within a range of 2.2-3.2, suggesting that a balance of these nutrients may be considered in recommendations for osteoporosis..

The Magnesium Status and Suggested Reference Ranges of Plasma Magnesium, Calcium, and Calcium/Magnesium Ratio in Chinese Adults over 45 Years Old

Magnesium (Mg) is an essential nutrient that participates in various enzymatic reactions and regulates important biological functions. The distribution and reference ranges in China have not been reported in populations more than 45 years old. This study aimed to assess the magnesium status and determine the reference values of plasma Mg, Ca, and Ca/Mg ratios for China's population more than 45 years old. A total of 2101 people were randomly selected from the China Nutrition and Health surveillance (CNHS) (2015-2017), considering the regional types and monitoring points. Then, 337 healthy individuals were further selected by a series of strict inclusion criteria to explore the reference range. The plasma magnesium and calcium were tested by inductively coupled plasma mass spectrometry (ICP-MS). The suggested reference values for plasma Mg, Ca, and Ca/Mg ratios were 0.75-1.14 mmol/L, 2.17-3.64 mmol/L, and 2.36-3.66, respectively. Taking 0.75 mmol/L as the lower cut-off limit, the prevalence of Mg deficiency was 6.66%, and the average level of plasma magnesium was 0.88 mmol/L for populations older than 45 years in China. In conclusion, this study provides the magnesium status and reference ranges for plasma Mg, Ca, and Ca/Mg ratio for Chinese people over 45 years old. The results of the recommended reference ranges in this study were very similar to our published results in women of reproductive age. Thus, the reference range of plasma magnesium in different populations in China was further improved.

The Inverse Association of Serum Magnesium with Papillary Thyroid Cancer in Thyroid Nodules: a Cross-Sectional Survey Based on Thyroidectomy Population

Magnesium is considered to play a role in preventing cancer. However, the association between serum magnesium and papillary thyroid cancer (PTC) remains unknown. We retrospectively reviewed records of all patients who underwent thyroidectomy with thyroid nodules confirmed pathologically as benign nodule or PTC at our institution from January 2016 to December 2020. Data including demographic characteristics, laboratory tests, and pathological features were analyzed in 5709 adult patients eventually. The subjects with benign nodules had a higher mean serum magnesium level than those with PTC (P < 0.001), and the proportions of PTCs decreased across quartiles of serum magnesium within the normal range. After adjustment for confounders, patients with the lowest quartile of serum magnesium had a higher prevalence of PTC than those with the highest quartile (OR = 1.421, 95%CI: 1.125-1.795, P for trend = 0.005), and the risk of PTC was 0.863 (95%CI: 0.795-0.936) for a per-SD change in serum magnesium. The contribution of serum magnesium remained in subgroup analysis (P for interaction for all analyses > 0.05). Based on the ROC curve, the cut-off value of serum magnesium used to differentiate benign nodules from PTCs was 935 μmol/L. Combining serum magnesium with other clinical indicators can improve the efficacy of predicting PTC. Our results showed that lower serum magnesium within the normal range was associated with a greater risk of PTC among patients with thyroid nodules considering thyroidectomy. Serum magnesium may be an independent protective factor against PTC and provide additional information on the odds of malignancy in uncertain thyroid nodules in combination with other clinical factors.

Pre-diagnostic dietary consumption of calcium and magnesium and calcium-to-magnesium intake ratio and ovarian cancer mortality: results from the ovarian cancer follow-up study (OOPS)

PURPOSE

Previous studies have indicated that dietary consumption of calcium (Ca), magnesium (Mg), and the Ca-to-Mg (Ca:Mg) ratio were associated with different health outcomes. However, no study has evaluated the association of pre-diagnostic Ca, Mg, and Ca:Mg ratio consumption with ovarian cancer (OC) survival.

METHODS

The aforementioned associations were investigated in a cohort of 853 Chinese women diagnosed with OC between 2015 and 2020. A validated food frequency questionnaire was used to evaluate pre-diagnostic diet information. Deaths were recorded until March 31, 2021 via medical records and active follow-up. Cox proportional hazards model was applied to calculate the adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

A total of 130 deaths were observed during a median follow-up of 37.2 months. After adjustment for potential confounders, pre-diagnostic Ca (HR_{< 600 vs. > 1000} = 1.45, 95% CI = 0.47-4.46, p for trend = 0.69) and Mg (HR_{< 250 vs. > 330} = 0.90, 95% CI = 0.39-2.08, p for trend = 0.77) intakes were found to be unrelated to OC survival, whereas a higher Ca:Mg intake ratio was significantly associated with worse survival (HR_{< 1.7 vs. > 2.5} = 2.72, 95% CI = 1.28-5.78, p for trend < 0.05). A significant result was also observed when treating the Ca:Mg ratio as a continuous variable (HR = 1.69, 95% CI = 1.12-2.55) for one-unit increment.

CONCLUSION

Pre-diagnostic consumption of Ca and Mg was unrelated to OC survival, while a higher Ca:Mg intake ratio was strongly associated with worse survival among OC patients.

Laser Ablation ICP-MS Analysis of Chemically Different Regions of Rat Prostate Gland with Implanted Cancer Cells

The comparison of tissues analyzed by LA-ICP-MS is challenging in many aspects, both medical and mathematical. The concept of distinguishing regions of interest (ROIs) was proposed in the literature, allowing for data reduction and targeted comparative analysis. ROIs can be drawn before any analysis, by indicating the anatomical parts of tissue, or after the first step of analysis, by using elemental distribution maps and characteristic regions of enrichment in selected elements. A simple method for identifying different regions, without the manual extraction of image fragments, is highly needed in biological experiments, where large groups of individuals (with samples taken from each of them) is very common. In the present study, two ROIs were distinguished: (1) tissue-rich in fat (and tissue-poor in water); and (2) tissue-rich in water (and tissue-poor in fat). ROIs were extracted mathematically, using an algorithm based on the relationship between 13C and 23Na signal intensities. A cut-off point was indicated in the point of the simultaneous decrease in 13C and increase in 23Na signal intensity. Separate analyses of chemically different ROIs allow for targeted comparison, which is a great advantage of laser ablation over liquid introductions to ICP-MS. In the present experiment, tissues were provided from animals with implanted prostate cancer cells as well as supplemented with mineral compounds particularly important both for prostate gland functions (Zn and Se) and neoplastic processes (Ca, Fe, and Cu). One of the goals was to try to determine whether dietary supplementation qualitatively and quantitatively affects the mineral composition of the prostate gland.

Diagnostic potential of trace metals concentration in expressed prostatic secretion and serum of patients with category IV prostatitis

BACKGROUND

The National Institutes of Health (NIH) category IV prostatitis is a painless prostate gland inflammation, just as its name implies, this type of prostatitis is related with inflammation of the prostate, but most men are not conscious of it. However, category IV prostatitis is fairly common in general populations and reported having indirect relationships with prostate cancer.

METHOD

We analyzed the concentration of zinc (Zn), copper (Cu), calcium (Ca) and magnesium (Mg) in expressed prostatic secretion (EPS) and serum of patients with category IV prostatitis and healthy controls, investigating the diagnostic potential of different metals in category IV prostatitis using a flame atomic absorption spectrometer (FAAS).

RESULTS

Metal concentration combined clinical characteristics analysis suggested that average level of Zn, Ca, Mg were significantly lower in the EPS of patients with category IV prostatitis (P-value< 0.000), while Cu level raised obviously (P-value< 0.000). And in the serum, mean concentrations of Ca was also found to increase significantly in the patients with category IV prostatitis compared to healthy controls. Moreover, the correlation analysis indicated that age showed a positive correlation with EPS Zn, Ca, Mg concentration (P-value< 0.05), while albumin correlates with EPS Zn, Ca, Mg concentration reversely (P-value< 0.05) in patients with category IV prostatitis.

CONCLUSION

Our report revealed that determination of the metal elements zinc, copper, calcium and magnesium in the serum and EPS could be a new and promising strategy for the rapid diagnosis of category IV prostatitis.

Magnesium treatment on methylation changes of transmembrane serine protease 2 (TMPRSS2)

OBJECTIVES

The viral entry of SARS-CoV-2 requires host-expressed TMPRSS2 to facilitate the viral spike protein priming. This study aims to test the hypothesis that magnesium (Mg) treatment leads to DNA methylation changes in TMPRSS2.

METHODS

This study is nested within the Personalized Prevention of Colorectal Cancer Trial, a double-blind 2 × 2 factorial randomized controlled trial, which enrolled 250 participants from Vanderbilt University Medical Center.

RESULTS

We found that 12 wk of personalized Mg treatment significantly increased 5-methylcytosine methylation at cg16371860 (TSS1500, promoter) by 7.2% compared to the placebo arm (decreased by 0.1%) in those ages < 65 y. The difference remained statistically significant after adjusting for age, sex, and baseline methylation as well as correction for false discovery rate (adjusted P = 0.014). Additionally, Mg treatment significantly reduced 5-hydroxymethylcytosine levels at cg26337277 (close proximity to TSS200 and the 5' untranslated region, promoter) by 2.3% compared to an increase of 7.1% in the placebo arm after adjusting for covariates in those ages < 65 y (P = 0.003). The effect remained significant at a false discovery rate of 0.10 (adjusted P = 0.088).

CONCLUSIONS

Among individuals ages < 65 y with calcium-to-magnesium intake ratios equal to or over 2.6, reducing the ratio to around 2.3 increased 5-methylcytosine modifications (i.e., cg16371860) and reduced 5-hydroxymethylcytosine modifications (i.e., cg26337277) in the TMPRSS2 gene. These findings, if confirmed, provide another mechanism for the role of Mg intervention in the prevention of COVID-19 and treatment of early and mild disease by modifying the phenotype of the TMPRSS2 genotype.

Serum gonadotropins, cortisol, PSA, and micronutrient levels among men with prostate carcinoma

Background

Prostate cancer (PrCa) is a malignant tumour of the prostate that has many associated risk factors. There is continuous rise in the incidence among adult blacks which is a reflection of racial differences in testosterone concentrations.

Methods

The study involves 50 PrCa patients attending or referred to two tertiary health Institutions and 25 healthy men as controls. Weight and height of participants were measured, and body mass index (BMI) was calculated. Ten millilitres of venous blood sample was collected from each participant, allowed to clot, and then centrifuged at 5000 rpm for 5 min at room temperature (22–28 °C) to obtain the serum. Serum cortisol, testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), total prostate-specific antigen (TPSA), free prostate-specific antigen (FPSA), selenium, copper, magnesium, and zinc were determined. Prostate ultrasonography and biopsy were also done for histopathological studies.

Result

From this study, a significant increase (p < 0.05) in weight, BMI, serum FPSA, TPSA, and copper; a non-significant increase (p > 0.05) in serum cortisol, testosterone; a significant decrease (p < 0.05) in serum LH, selenium, zinc, and magnesium; and a non-significant decrease (p > 0.05) in serum FSH were observed among people living with PrCa when compared to the controls. However, no significant difference (p > 0.05) was observed in the height between the two groups. Ultrasonography and histology revealed evidence of prostatitis, hypertrophy, and carcinoma among the test group.

Conclusion

It can be concluded that PrCa is associated with increase serum cortisol, testosterone, and copper; and decreased serum LH, FSH, selenium, zinc, and magnesium concentrations and combination of biochemical, ultrasonographic, and histologic features are of diagnostic importance.

Magnesium Depletion Score (MDS) Predicts Risk of Systemic Inflammation and Cardiovascular Mortality among US Adults

BACKGROUND

Kidney reabsorption of magnesium (Mg) is essential for homeostasis.

OBJECTIVES

We developed and validated models with the kidney reabsorption-related magnesium depletion score (MDS) to predict states of magnesium deficiency and disease outcomes.

METHODS

MDS was validated in predicting body magnesium status among 77 adults (aged 62 ± 8 y, 51% men) at high risk of magnesium deficiency in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (registered at clinicaltrials.gov as NCT01105169) using the magnesium tolerance test (MTT). We then validated MDS for risk stratification and for associations with inflammation and mortality among >10,000 US adults (weighted: aged 48 ± 0.3 y, 47% men) in the NHANES, a nationally representative study. A proportional hazards regression model was used for associations between magnesium intake and the MDS with risks of total and cardiovascular disease (CVD) mortality.

RESULTS

In the PPCCT, the area under the receiver operating characteristic (ROC) curve (AUC) for magnesium deficiency was 0.63 (95% CI: 0.50, 0.76) for the model incorporating the MDS with sex and age compared with 0.53 (95% CI: 0.40, 0.67) for the model with serum magnesium alone. In the NHANES, mean serum C-reactive protein significantly increased with increasing MDS (P-trend < 0.01) after adjusting for age and sex and other covariates, primarily among individuals with magnesium intake less than the Estimated Average Requirement (EAR; P-trend < 0.05). Further, we found that low magnesium intake was longitudinally associated with increased risks of total and CVD mortality only among those with magnesium deficiency predicted by MDS. MDS was associated with increased risks of total and CVD mortality in a dose-response manner only among those with magnesium intake less than the EAR.

CONCLUSIONS

The MDS serves as a promising measure in identifying individuals with magnesium deficiency who may benefit from increased intake of magnesium to reduce risks of systemic inflammation and CVD mortality. This lays a foundation for precision-based nutritional interventions.

Effects of quercetin on the alterations of serum elements in chronic unpredictable mild stress-induced depressed rats

Depression is a common and serious psychiatric disorder, but current conventional antidepressants have limited efficacy and significant side effects. Thus, better antidepressants are urgently needed. This study aimed to investigate the antidepressant-like effects and potential mechanism of quercetin by evaluating the changes of serum elements in chronic unpredictable mild stress (CUMS) rats. Based on the results of the sucrose preference test (SPT), 96 rats were randomly assigned to six groups: control, different dosages of quercetin (10 and 50 mg/kg·bw, respectively), depressed, and different dosages quercetin plus depressed groups. After 8 weeks of CUMS modeling, rat serum was collected. Fifteen elements in serum were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and related enzyme indicators, antioxidant indicators, and inflammatory cytokines were detected to further explore the potential mechanism. Besides, the accuracy and precision of the method were evaluated. The results showed that the levels of iron (Fe), copper (Cu), and calcium (Ca) in serum significantly increased (p ≤ 0.001), while the levels of magnesium (Mg), zinc (Zn), selenium (Se), and cobalt (Co) significantly decreased (p ≤ 0.001) in depressed group compared with the control group. The levels of the remaining eight elements did not change significantly. When high-dose quercetin was administered to depressed rats, the levels of the above seven elements significantly restored (p ≤ 0.001). This study suggests that quercetin (50 mg/kg·bw) has a regulatory effect on serum elements in CUMS rats, which may be mediated by reducing oxidative stress, inhibiting inflammation, and regulating a variety of neurotransmitter systems.

Magnesium Treatment on Methylation Changes of Transmembrane Serine Protease 2 (TMPRSS2)

BACKGROUND

The viral entry of SARS-CoV-2 requires host-expressed TMPRSS2 to facilitate the viral spike (S) protein priming.

OBJECTIVES

To test the hypothesis that Mg treatment leads to DNA methylation changes in TMPRSS2 .

METHODS

This study is nested within the Personalized Prevention of Colorectal Cancer Trial (PPCCT), a double-blind 2×2 factorial randomized controlled trial, which enrolled 250 participants from Vanderbilt University Medical Center. Target doses for both Mg and placebo arms were personalized.

RESULTS

We found that 12-week of personalized Mg treatment significantly increased 5-mC methylation at cg16371860 (TSS1500, promoter) by 7.2% compared to placebo arm (decreased by 0.1%) in those aged < 65 years old. The difference remained statistically significant after adjusting for age, sex and baseline methylation as well as FDR correction (FDR-adjusted P =0.014). Additionally, Mg treatment significantly reduced 5-hmC level at cg26337277 (close proximity to TSS200 and 5'UTR, promoter) by 2.3% compared to increases by 7.1% in the placebo arm after adjusting for covariates in those aged < 65 years old ( P =0.003). The effect remained significant at FDR of 0.10 (adjusted P value=0.088).

CONCLUSION

Among individuals aged younger than 65 years with the Ca:Mg intake ratios equal to or over 2.6, reducing Ca:Mg ratios to around 2.3 increased 5-mC modifications (i.e. cg16371860) and reduced 5-hmC modifications (i.e. cg26337277) in the TMPRSS2 gene. These findings, if confirmed, provide another mechanism for the role of Mg intervention for the prevention of COVID-19 and treatment of early and mild disease by modifying the phenotype of the TMPRSS2 genotype.

Beneficial Effects of Intravenous Magnesium Administration During Robotic Radical Prostatectomy: A Randomized Controlled Trial

INTRODUCTION

Robotic radical prostatectomy requires prolonged pneumoperitoneum and a steep Trendelenburg position. Magnesium can attenuate the stress response and hemodynamic perturbations. This study aimed to evaluate the effects of intravenous magnesium administration on hemodynamics and the stress response in patients undergoing robotic radical prostatectomy.

METHODS

In this prospective, double-blind, randomized controlled study, 52 patients undergoing robotic radical prostatectomy were randomized into two groups: 26 in the magnesium group and 26 in the control group. The patients in the magnesium group received magnesium sulfate 50 mg/kg intravenously, followed by infusion at a rate of 10 mg/kg/h during surgery. The patients in the control group received an equal volume of 0.9% saline. The primary outcomes were the changes in heart rate and mean arterial pressure (MAP) during surgery. The serum stress hormones (adrenocorticotropic hormone, cortisol, epinephrine, and norepinephrine) were also measured.

RESULTS

MAP showed a significant intergroup difference over time (P_group*time = 0.017); it increased significantly at 5 min after Trendelenburg position in the control group and decreased significantly at 30 min after Trendelenburg position in the magnesium group. The intergroup difference in the change in cortisol concentrations was significant over time (P_group*time = 0.006). The cortisol concentration decreased significantly from baseline to 24 h after surgery in the magnesium group but did not change significantly in the control group. The requirement for intraoperative remifentanil was 35% lower in the magnesium group (P = 0.011), and the severity of postoperative pain at 30 min and 6 h after surgery was also lower in the magnesium group (P = 0.024 and P = 0.015).

CONCLUSION

There is a possibility that intravenous magnesium administration during robotic radical prostatectomy reduces the increases in arterial pressure, cortisol concentrations, opioid requirements, and postoperative pain.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02833038.

Plasma Magnesium Concentrations and Risk of Incident Cancer in Adults with Hypertension: A Nested Case-Control Study

OBJECTIVE

The association between plasma magnesium and risk of incident cancer remains inconclusive in previous studies. We aimed to investigate the prospective relationship of baseline plasma magnesium concentrations with the risk of incident cancer and to examine possible effect modifiers.

METHODS

A nested case-control study with 228 incident cancer cases and 228 matched controls was conducted using data from the China Stroke Primary Prevention Trial (CSPPT), a randomized, double-blind, controlled trial, conducted from May 2008 to August 2013. Study outcomes included incident cancer and its subtypes.

RESULTS

When plasma magnesium concentrations were assessed as quartiles, a significantly higher incident risk of total cancer was found in participants in quartile 1 (<0.76 mmol/L; odds ratio [OR] = 2.70; 95% CI: 1.33-5.49) and quartile 4 (≥0.89 mmol/L; OR = 2.05; 95% CI: 1.12-3.76), compared with those in quartile 3 (0.83 to <0.89 mmol/L). In cancer site-specific analyses, similar trends were found for gastrointestinal cancer, esophageal cancer, gastric cancer, breast cancer, lung cancer, and other cancers. Furthermore, none of the variables, including age, sex, current smoking status, current alcohol intake, BMI, systolic blood pressure, and total cholesterol levels at baseline significantly modified the association between plasma magnesium and cancer risk.

CONCLUSIONS

Both low and high plasma magnesium concentrations were significantly associated with an increased incident risk of cancer, compared with the reference concentrations of 0.83 to <0.89 mmol/L among hypertensive adults.

A Deep Learning Framework Identifies Pathogenic Noncoding Somatic Mutations from Personal Prostate Cancer Genomes

Our understanding of noncoding mutations in cancer genomes has been derived primarily from mutational recurrence analysis by aggregating clinical samples on a large scale. These cohort-based approaches cannot directly identify individual pathogenic noncoding mutations from personal cancer genomes. Therefore, although most somatic mutations are localized in the noncoding cancer genome, their effects on driving tumorigenesis and progression have not been systematically explored and noncoding somatic alleles have not been leveraged in current clinical practice to guide personalized screening, diagnosis, and treatment. Here, we present a deep learning framework to capture pathogenic noncoding mutations in personal cancer genomes, which perturb gene regulation by altering chromatin architecture. We deployed the system specifically for localized prostate cancer by integrating large-scale prostate cancer genomes and the prostate-specific epigenome. We exhaustively evaluated somatic mutations in each patient's genome and agnostically identified thousands of somatic alleles altering the prostate epigenome. Functional genomic analyses subsequently demonstrated that affected genes displayed differential expression in prostate tumor samples, were vulnerable to expression alterations, and were convergent onto androgen receptor-mediated signaling pathways. Accumulation of pathogenic regulatory mutations in these affected genes was predictive of clinical observations, suggesting potential clinical utility of this approach. Overall, the deep learning framework has significantly expanded our view of somatic mutations in the vast noncoding genome, uncovered novel genes in localized prostate cancer, and will foster the development of personalized screening and therapeutic strategies for prostate cancer. SIGNIFICANCE: This study's characterization of the noncoding genome in prostate cancer reveals mutational signatures predictive of clinical observations, which may serve as a powerful prognostic tool in this disease.

Associations between calcium and magnesium intake and the risk of incident oesophageal cancer: an analysis of the NIH-AARP Diet and Health Study prospective cohort

BACKGROUND

Risk reduction through dietary modifications is an adjunct strategy for prevention of oesophageal cancer, a leading cause of cancer-related mortality and morbidity worldwide. We aimed to estimate the association between calcium and magnesium intakes and incident oesophageal cancer (OC).

METHODS

We conducted a retrospective analysis of the NIH-AARP Diet and Health Study prospective cohort. We used multivariable Cox proportional hazard modeling to estimate the association between total intakes and incident OC overall and by histology (oesophageal squamous cell carcinoma (OSCC) and adenocarcinoma (OAC)). Sensitivity and stratified analyses were performed.

RESULTS

Among 536,359 included respondents, 1414 incident OCs occurred over 6.5 million person-years follow-up time. Increasing dietary calcium intake was associated with an adjusted 32-41% lower risk of OSCC compared to the lowest quartile (p-trend 0.01). There was a positive association between increasing magnesium intake and OAC risk, but only among participants with low calcium:magnesium intake ratios (p-trend 0.04). There was a significant interaction with smoking status.

CONCLUSIONS

Based on a retrospective analysis of the NIH-AARP Diet and Health Study prospective cohort, dietary intakes of calcium and magnesium were significantly associated with risk of OSCC and, among certain participants, OAC, respectively. If validated, these findings could inform dietary modifications among at-risk individuals. Mechanistic investigations would provide additional insight.

Treatment Stratification of Patients with Metastatic Castration-Resistant Prostate Cancer by Machine Learning

Prostate cancer is the most common cancer in men in the Western world. One-third of the patients with prostate cancer will develop resistance to hormonal therapy and progress into metastatic castration-resistant prostate cancer (mCRPC). Currently, docetaxel is a preferred treatment for mCRPC. However, about 20% of the patients will undergo early therapeutic failure owing to adverse events induced by docetaxel-based chemotherapy. There is an emergent need for a computational model that can accurately stratify patients into docetaxel-tolerable and docetaxel-intolerable groups. Here we present the best-performing algorithm in the Prostate Cancer DREAM Challenge for predicting adverse events caused by docetaxel treatment. We integrated the survival status and severity of adverse events into our model, which is an innovative way to complement and stratify the treatment discontinuation information. Critical stratification biomarkers were further identified in determining the treatment discontinuation. Our model has the potential to improve future personalized treatment in mCRPC.

Associations between calcium and magnesium intake and the risk of incident gastric cancer: A prospective cohort analysis of the National Institutes of Health-American Association of Retired Persons (NIH-AARP) Diet and Health Study

Gastric cancer remains a leading cause of cancer-related mortality. Identifying dietary and other modifiable disease determinants has important implications for risk attenuation in susceptible individuals. Our primary aim was to estimate the association between dietary and supplemental intakes of calcium and magnesium and the risk of incident gastric cancer. We conducted a prospective cohort analysis of the National Institutes of Health-American Association of Retired Persons Diet and Health Study. We used Cox proportional hazard modeling to estimate the association between calcium and magnesium intakes with risk of incident gastric adenocarcinoma (GA) overall and by anatomic location, noncardia GA (NCGA) and cardia GA (CGA). A total of 536,403 respondents (59% males, 41% females) were included for analysis, among whom 1,518 incident GAs (797 NCGA and 721 CGA) occurred. Increasing calcium intake was associated with lower risk of GA overall (p-trend = 0.05), driven primarily by the association with NCGA, where the above median calcium intakes were associated with a 23% reduction in risk compared to the lowest quartile (p-trend = 0.05). This magnitude of NCGA risk reduction was greater among nonwhite ethnic group and Hispanics (hazard ratio [HR] 0.51, 95% confidence interval [CI]: 0.24-1.07, p-trend = 0.04), current/former smokers (HR 0.58, 95% CI: 0.41-0.81), obese individuals (HR 0.54, 95% CI: 0.31-0.96) and those with high NCGA risk scores (HR 0.50, 95% CI: 0.31-0.80). Among men only, increasing magnesium intake was associated with 22-27% reduced risk of NCGA (p-trend = 0.05), while for the cohort, dietary magnesium intake in the highest vs. lowest quartile was associated with a 34% reduced risk of NCGA (HR 0.66, 95% CI: 0.48-0.90). These findings have important implications for risk factor modification. Future investigations are needed not only to confirm our results, but to define mechanisms underlying these associations.

Prospective Association of Serum and Dietary Magnesium with Colorectal Cancer Incidence

BACKGROUND

Laboratory and epidemiologic research suggests a protective role of magnesium in colorectal cancer development. We estimated the associations of serum and dietary magnesium with colorectal cancer incidence in the Atherosclerosis Risk in Communities (ARIC) study.

METHODS

Serum magnesium concentration was measured in blood collected twice (1987-1989 and 1990-1992) and averaged. Dietary magnesium was assessed by food-frequency questionnaire administered twice (1987-1989 and 1993-1995) and averaged. For both dietary and serum magnesium, the averaged measures were categorized into quintiles for analysis. Analyses included 315 colorectal cancer cases among 13,009 participants for serum magnesium (followed for a median of 20.4 years), and 256 cases among 10,971 participants for dietary magnesium (followed for a median of 17.5 years). Cox proportional hazards regression was used to calculate multivariable-adjusted HRs and 95% confidence intervals (CI).

RESULTS

Multivariable-adjusted HRs (95% CI) of colorectal cancer for the highest four quintiles compared with the first quintile of serum magnesium were as follows: Q2: 0.70 (0.49-0.99); Q3: 0.68 (0.47-1.00); Q4: 0.87 (0.62-1.21); and Q5: 0.79 (0.57-1.11; P trend = 0.04). An inverse association was present in females (HR for Q5 vs. Q1: 0.59, 95% CI: 0.36-0.98, P trend = 0.01), but not males (HR for Q5 vs. Q1: 1.10, 95% CI: 0.67-1.79, P trend = 0.92; P interaction = 0.34). Dietary magnesium was not statistically significantly associated with colorectal cancer risk.

CONCLUSIONS

Our study found a higher risk of colorectal cancer with lower serum magnesium among females, but not males.

IMPACT

If our findings are confirmed, maintaining adequate serum magnesium levels may be important for colorectal cancer prevention.

Blood and dietary magnesium levels are not linked with lower prostate cancer risk in black or white men

Recent studies suggest a diet low in dietary magnesium intake or lower blood magnesium levels is linked with increased prostate cancer risk. This study investigates the race-specific link between blood magnesium and calcium levels, or dietary magnesium intake, and the diagnosis of low-grade and high-grade prostate cancer. The study included 637 prostate cancer cases and 715 biopsy-negative controls (50% black) recruited from Nashville, TN or Durham, NC. Blood was collected at the time of recruitment, and dietary intake was assessed by food frequency questionnaire. Percent genetic African ancestry was determined as a compliment to self-reported race. Blood magnesium levels and dietary magnesium intake were significantly lower in black compared to white men. However, magnesium levels or intake were not associated with risk of total prostate cancer or aggressive prostate cancer. Indeed, a higher calcium-to-magnesium diet intake was significantly protective for high-grade prostate cancer in black (OR = 0.66 (0.45, 0.96), p = 0.03) but not white (OR = 1.00 (0.79, 1.26), p = 0.99) men. In summary, there was a statistically significant difference in magnesium intake between black and white men, but the biological impact was unclear, and we did not confirm a lower prostate cancer risk associated with magnesium levels.

The Divalent Elements Changes in Early Stages of Chronic Kidney Disease

As the glomerular filtration rate (GFR) decreases, it can cause imbalance in some divalent elements. These imbalances can cause increased oxidative stress in patients with renal impairment. The aim of present study was to investigate the changes of these divalent elements with CKD progression. One hundred and ninety-four patients with chronic kidney diseases (CKD) were divided into five stages, stage 1, 2, 3a, 3b, 4, and were recruited into this study. The divalent elements, calcium, magnesium, phosphorus, as well as iron, zinc, and copper were determined in clinical chemistry analyzer. Higher CKD stages were found to be associated with increased levels of phosphorus and copper; P_trend values were 0.002 and 0.004, respectively. Also, higher CKD stages were associated with decreased levels of zinc; P_trend value was 0.002, after adjustment for age, gender, smoke, education, diabetes, hypertension, and BMI. Decreased levels of zinc and elevated levels of phosphorus and copper might increase the oxidative stress and complications in CKD patients. Future randomized studies are needed to show whether adjusting dietary intake of phosphorus, copper, and zinc might affect the progression of CKD.

Metastatic State of Cancer Cells May Be Indicated by Adhesion Strength

Cancer cells within a tumor are heterogeneous and only a small fraction are able to form secondary tumors. Universal biological markers that clearly identify potentially metastatic cells are limited, which complicates isolation and further study. However, using physical rather than biological characteristics, we have identified Mg²⁺- and Ca²⁺-mediated differences in adhesion strength between metastatic and nonmetastatic mammary epithelial cell lines, which occur over concentration ranges similar to those found in tumor stroma. Metastatic cells exhibit remarkable heterogeneity in their adhesion strength under stromal-like conditions, unlike their nonmetastatic counterparts, which exhibit Mg²⁺- and Ca²⁺-insensitive adhesion. This heterogeneity is the result of increased sensitivity to Mg²⁺- and Ca²⁺-mediated focal adhesion disassembly in metastatic cells, rather than changes in integrin expression or focal adhesion phosphorylation. Strongly adherent metastatic cells exhibit less migratory behavior, similar to nonmetastatic cell lines but contrary to the unselected metastatic cell population. Adhesion strength heterogeneity was observed across multiple cancer cell lines as well as isogenically, suggesting that adhesion strength may serve as a general marker of metastatic cells.

Magnesium improves cisplatin-mediated tumor killing while protecting against cisplatin-induced nephrotoxicity

Approximately 30% of all cancer patients treated with cisplatin, a widely used broad-spectrum chemotherapeutic agent, experience acute kidney injury (AKI). Almost all patients receiving cisplatin have magnesium (Mg) losses, which are proposed to aggravate AKI. Currently, there are no methods to successfully treat or prevent cisplatin-AKI. Whereas Mg supplementation has been shown to reduce AKI in experimental models and several small clinical trials, the effects of Mg status on tumor outcomes in immunocompetent tumor-bearing mice and humans have not been investigated. The purpose of this study was to further examine the effects of Mg deficiency (±Mg supplementation) on cisplatin-mediated AKI and tumor killing in immunocompetent mice bearing CT26 colon tumors. Using a model where cisplatin alone (20 mg/kg cumulative dose) produced minimal kidney injury, Mg deficiency significantly worsened cisplatin-mediated AKI, as determined by biochemical markers (blood urea nitrogen and plasma creatinine) and histological renal changes, as well as markers of renal oxidative stress, inflammation, and apoptosis. By contrast, Mg supplementation blocked cisplatin-induced kidney injury. Using LLC-PK₁ renal epithelial cells, we observed that Mg deficiency or inhibition of Mg uptake significantly enhanced cisplatin-induced cytotoxicity, whereas Mg supplementation protected against cytotoxicity. However, neither Mg deficiency nor inhibition of Mg uptake impaired cisplatin-mediated killing of CT26 tumor cells in vitro. Mg deficiency was associated with significantly larger CT26 tumors in BALB/c mice when compared with normal-fed control mice, and Mg deficiency significantly reduced cisplatin-mediated tumor killing in vivo. Finally, Mg supplementation did not compromise cisplatin's anti-tumor efficacy in vivo.

Inherited and acquired disorders of magnesium homeostasis

PURPOSE OF REVIEW

Magnesium (Mg) imbalances are frequently overlooked. Hypermagnesemia usually occurs in preeclamptic women after Mg therapy or in end-stage renal disease patients, whereas hypomagnesemia is more common with a prevalence of up to 15% in the general population. Increasing evidence points toward a role for mild-to-moderate chronic hypomagnesemia in the pathogenesis of hypertension, type 2 diabetes mellitus, and metabolic syndrome.

RECENT FINDINGS

The kidneys are the major regulator of total body Mg homeostasis. Over the last decade, the identification of the responsible genes in rare genetic disorders has enhanced our understanding of how the kidney handles Mg. The different genetic disorders and medications contributing to abnormal Mg homeostasis are reviewed.

SUMMARY

As dysfunctional Mg homeostasis contributes to the development of many common human disorders, serum Mg deserves closer monitoring. Hypomagnesemic patients may be asymptomatic or may have mild symptoms. In severe hypomagnesemia, patients may present with neurological symptoms such as seizures, spasms, or cramps. Renal symptoms include nephrocalcinosis and impaired renal function. Most conditions affect tubular Mg reabsorption by disturbing the lumen-positive potential in the thick ascending limb or the negative membrane potential in the distal convoluted tubule.

Calcium - Magnesium imbalance implicated in benign prostatic hyperplasia and restoration by a phytotherapeutic drug - Croton membranaceus Müll.Arg

Background

Calcium (Ca)- magnesium (Mg) imbalance is implicated in prostate cancer. Ca/Mg ratio increases or decreases with proliferation or apoptosis, respectively. The study examined whether this Ca/Mg imbalance exists in BPH patients and the effect of a phytotherapeutic drug on the Ca/Mg ratio.

Methods

Thirty (30) BPH patients who used the ethanolic root extract of Croton membranaceus (60 mg/day) for 3 months were examined for serum Ca, Mg, phosphate, parathyroid hormone (PTH), vitamin D, prostate specific antigen (PSA) levels and renal function tests (RFT) before (BT) and after treatment (AT) alongside thirty (30) controls. Twenty (20) trace element including Mg and Ca were determined in the drug by neutron activation analysis (NAA).

Results

RFT, PTH and vitamin D for BT, AT and controls (C) were normal. Mean PSA was 1.0 ± 0.64 (C), 27.9 ± 19.0 (BT) and 16.2 ± 11.8 ng/mL (AT) (p = 0.002). Mg, Ca/Mg ratio BT, AT and control were significantly different (p = 0.0001, respectively). After treatment, Mg and Ca/Mg ratio were not different from controls. The prevalence of Ca/Mg imbalance was 80% (BT), 13.3% (AT) and 3.3% (control group).

Conclusion

Ca/Mg ratio imbalance is associated with BPH. This has previously not been demonstrated. The imbalance was significantly corrected after treatment with the phytotherapeutic drug.

The Association Between Calcium, Magnesium, and Ratio of Calcium/Magnesium in Seminal Plasma and Sperm Quality

The study aimed to examine the relationships between calcium, magnesium, and calcium/magnesium ratio in semen plasma and sperm quality. It was a cross-sectional study based on a program aiming at promoting the reproductive health in less-developed areas. A total of 515 men aged between 18 and 55 years provided semen specimens at family planning clinics in Sandu County, Guizhou Province, China. Total calcium and magnesium concentrations in semen plasma were measured with flame atomic absorption spectrometry. Sperm quality, including sperm motility and concentration, was evaluated by using a computer-assisted sperm analysis method. The medians of seminal plasma calcium, magnesium, and zinc concentrations were 9.61, 4.41, and 2.23 mmol/l, respectively. Calcium concentration and calcium/magnesium ratio were negatively associated with sperm concentrations (β = -0.47, P = 0.0123 for calcium; β = -0.25, P = 0.0393 for calcium/magnesium ratio) after adjusting for zinc and other covariates. In stratified analyses, the association between calcium and sperm concentrations only persisted among subjects with a calcium/magnesium ratio of ≤2.5 (β = -0.71, P = 0.0268). In the same stratum, magnesium was associated with increased sperm concentration (β = 0.73, P = 0.0386). Among subjects with a calcium/magnesium ratio of >2.5, neither calcium nor magnesium was associated with sperm concentration. In conclusion, total calcium and magnesium concentrations were associated with sperm concentration among subjects with a lower calcium/magnesium ratio. The calcium and magnesium ratio had a modifying effect on the associations of calcium and magnesium with sperm concentration.

Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Status Interact with Vitamin D and/or Calcium Status?

Although much is known about magnesium, its interactions with calcium and vitamin D are less well studied. Magnesium intake is low in populations who consume modern processed-food diets. Low magnesium intake is associated with chronic diseases of global concern [e.g., cardiovascular disease (CVD), type 2 diabetes, metabolic syndrome, and skeletal disorders], as is low vitamin D status. No simple, reliable biomarker for whole-body magnesium status is currently available, which makes clinical assessment and interpretation of human magnesium research difficult. Between 1977 and 2012, US calcium intakes increased at a rate 2-2.5 times that of magnesium intakes, resulting in a dietary calcium to magnesium intake ratio of >3.0. Calcium to magnesium ratios <1.7 and >2.8 can be detrimental, and optimal ratios may be ∼2.0. Background calcium to magnesium ratios can affect studies of either mineral alone. For example, US studies (background Ca:Mg >3.0) showed benefits of high dietary or supplemental magnesium for CVD, whereas similar Chinese studies (background Ca:Mg <1.7) showed increased risks of CVD. Oral vitamin D is widely recommended in US age-sex groups with low dietary magnesium. Magnesium is a cofactor for vitamin D biosynthesis, transport, and activation; and vitamin D and magnesium studies both showed associations with several of the same chronic diseases. Research on possible magnesium and vitamin D interactions in these human diseases is currently rare. Increasing calcium to magnesium intake ratios, coupled with calcium and vitamin D supplementation coincident with suboptimal magnesium intakes, may have unknown health implications. Interactions of low magnesium status with calcium and vitamin D, especially during supplementation, require further study.

The Importance of Magnesium in the Human Body: A Systematic Literature Review

Magnesium, the second and fourth most abundant cation in the intracellular compartment and whole body, respectively, is of great physiologic importance. Magnesium exists as bound and free ionized forms depending on temperature, pH, ionic strength, and competing ions. Free magnesium participates in many biochemical processes and is most commonly measured by ion-selective electrode. This analytical approach is problematic because complete selectivity is not possible due to competition with other ions, i.e., calcium, and pH interference. Unfortunately, many studies have focused on measurement of total magnesium rather than its free bioactive form making it difficult to correlate to disease states. This systematic literature review presents current analytical challenges in obtaining accurate and reproducible test results for magnesium.

Magnesium protects against cisplatin-induced acute kidney injury without compromising cisplatin-mediated killing of an ovarian tumor xenograft in mice

Cisplatin, a commonly used chemotherapeutic for ovarian and other cancers, leads to hypomagnesemia in most patients and causes acute kidney injury (AKI) in 25-30% of patients. Previously, we showed that magnesium deficiency worsens cisplatin-induced AKI and magnesium replacement during cisplatin treatment protects against cisplatin-mediated AKI in non-tumor-bearing mice (Solanki MH, Chatterjee PK, Gupta M, Xue X, Plagov A, Metz MH, Mintz R, Singhal PC, Metz CN. Am J Physiol Renal Physiol 307: F369-F384, 2014). This study investigates the role of magnesium in cisplatin-induced AKI using a human ovarian tumor (A2780) xenograft model in mice and the effect of magnesium status on tumor growth and the chemotherapeutic efficacy of cisplatin in vivo. Tumor progression was unaffected by magnesium status in saline-treated mice. Cisplatin treatment reduced tumor growth in all mice, irrespective of magnesium status. In fact, cisplatin-treated magnesium-supplemented mice had reduced tumor growth after 3 wk compared with cisplatin-treated controls. While magnesium status did not interfere with tumor killing by cisplatin, it significantly affected renal function following cisplatin. Cisplatin-induced AKI was enhanced by magnesium deficiency, as evidenced by increased blood urea nitrogen, creatinine, and other markers of renal damage. This was accompanied by reduced renal mRNA expression of the cisplatin efflux transporter Abcc6. These effects were significantly reversed by magnesium replacement. On the contrary, magnesium status did not affect the mRNA expression of cisplatin uptake or efflux transporters by the tumors in vivo. Finally, magnesium deficiency enhanced platinum accumulation in the kidneys and renal epithelial cells, but not in the A2780 tumor cells. These findings demonstrate the renoprotective role of magnesium during cisplatin AKI, without compromising the chemotherapeutic efficacy of cisplatin in an ovarian tumor-bearing mouse model.

Pleiotropy between genetic markers of obesity and risk of prostate cancer

BACKGROUND

To address inconsistent findings of obesity and prostate cancer risk, we analyzed the association between prostate cancer and genetic markers of obesity and metabolism.

METHODS

Analyses included 176,520 single-nucleotide polymorphisms (SNP) associated with 23 metabolic traits. We examined the association between SNPs and prostate cancer in 871 cases and 906 controls, including 427 high-grade cases with Gleason ≥ 7. Genetic risk scores (GRS) for body mass index (BMI) and waist-to-hip ratio (WHR) were also created by summing alleles associated with increasing BMI or WHR.

RESULTS

Prostate cancer was associated with five loci, including cyclin M2, with P values less than 1 × 10(-4). In addition, the WHR GRS was associated with high-grade prostate cancer versus controls [OR, 1.05; 95% confidence interval (CI), 1.00-1.11; P = 0.048] and high-grade prostate cancer versus low-grade prostate cancer (OR, 1.07; 95% CI, 1.01-1.13; P = 0.03). None of these findings exceeds the threshold for significance after correction for multiple testing.

CONCLUSIONS

Variants in genes known to be associated with metabolism and obesity may be associated with prostate cancer. We show evidence for pleiotropy between WHR GRS and prostate cancer grade. This finding is consistent with the function of several WHR genes and previously described relationships with cancer traits.

IMPACT

Limitations in standard obesity measures suggest alternative characterizations of obesity may be needed to understand the role of metabolic dysregulation in prostate cancer. The underlying genetics of WHR or other Metabochip SNPs, while not statistically significant beyond multiple testing thresholds within our sample size, support the metabolic hypothesis of prostate carcinogenesis and warrant further investigation in independent samples.

Magnesium intake and risk of amyotrophic lateral sclerosis: results from five large cohort studies

A low magnesium intake has been suggested to be associated with amyotrophic lateral sclerosis (ALS) in pathological and case-control studies, but prospective studies in humans are lacking. The relation between dietary intake of magnesium and ALS risk was explored in five large prospective cohort studies (the Nurses' Health Study, the Health Professionals Follow-up Study, the Cancer Prevention Study II Nutrition Cohort, the Multiethnic Cohort Study, and the National Institutes of Health - AARP Diet and Health Study), comprising over 1,050,000 males and females contributing 1093 cases of ALS during a mean of 15 years of follow-up. Cox proportional hazards models were used within each cohort, and cohort-specific estimates were subsequently pooled using a random-effects model. Results demonstrated that dietary magnesium intake was not associated with ALS risk, relative risk 1.07, 95% confidence interval 0.88 - 1.31 comparing the highest quintile of intake with the lowest. This finding does not support a protective effect of magnesium intake on ALS risk. Further analyses should explore magnesium intake in combination with heavy metal exposure and genetic variants affecting magnesium absorption.

Modifying effect of calcium/magnesium intake ratio and mortality: a population-based cohort study

OBJECTIVES

Magnesium (Mg) and calcium (Ca) antagonise each other in (re)absorption, inflammation and many other physiological activities. Based on mathematical estimation, the absorbed number of Ca or Mg depends on the dietary ratio of Ca to Mg intake. We hypothesise that the dietary Ca/Mg ratio modifies the effects of Ca and Mg on mortality due to gastrointestinal tract cancer and, perhaps, mortality due to diseases occurring in other organs or systems.

DESIGN

Prospective studies.

SETTING

Population-based cohort studies (The Shanghai Women's Health Study and the Shanghai Men's Health Study) conducted in Shanghai, China.

PARTICIPANTS

74 942 Chinese women aged 40-70 years and 61 500 Chinese men aged 40-74 years participated in the study.

PRIMARY OUTCOME MEASURES

All-cause mortality and disease-specific mortality.

RESULTS

In this Chinese population with a low Ca/Mg intake ratio (a median of 1.7 vs around 3.0 in US populations), intakes of Mg greater than US Recommended Daily Allowance (RDA) levels (320 mg/day among women and 420 mg/day among men) were related to increased risks of total mortality for both women and men. Consistent with our hypothesis, the Ca/Mg intake ratio significantly modified the associations of intakes of Ca and Mg with mortality risk, whereas no significant interactions between Ca and Mg in relation to outcome were found. The associations differed by gender. Among men with a Ca/Mg ratio >1.7, increased intakes of Ca and Mg were associated with reduced risks of total mortality, and mortality due to coronary heart diseases. In the same group, intake of Ca was associated with a reduced risk of mortality due to cancer. Among women with a Ca/Mg ratio ≤1.7, intake of Mg was associated with increased risks of total mortality, and mortality due to cardiovascular diseases and colorectal cancer.

CONCLUSIONS

These results, if confirmed, may help to understand the optimal balance between Ca and Mg in the aetiology and prevention of these common diseases and reduction in mortality.

Increase in serum Ca2+/Mg2+ ratio promotes proliferation of prostate cancer cells by activating TRPM7 channels

TRPM7 is a novel magnesium-nucleotide-regulated metal current (MagNuM) channel that is regulated by serum Mg²⁺ concentrations. Changes in Mg²⁺ concentration have been shown to alter cell proliferation in various cells; however, the mechanism and the ion channel(s) involved have not yet been identified. Here we demonstrate that TRPM7 is expressed in control and prostate cancer cells. Supplementation of intracellular Mg-ATP or addition of external 2-aminoethoxydiphenyl borate inhibited MagNuM currents. Furthermore, silencing of TRPM7 inhibited whereas overexpression of TRPM7 increased endogenous MagNuM currents, suggesting that these currents are dependent on TRPM7. Importantly, although an increase in the serum Ca²⁺/Mg²⁺ ratio facilitated Ca²⁺ influx in both control and prostate cancer cells, a significantly higher Ca²⁺ influx was observed in prostate cancer cells. TRPM7 expression was also increased in cancer cells, but its expression was not dependent on the Ca²⁺/Mg²⁺ ratio per se. Additionally, an increase in the extracellular Ca²⁺/Mg²⁺ ratio led to a significant increase in cell proliferation of prostate cancer cells when compared with control cells. Consistent with these results, age-matched prostate cancer patients also showed a subsequent increase in the Ca²⁺/Mg²⁺ ratio and TRPM7 expression. Altogether, we provide evidence that the TRPM7 channel has an important role in prostate cancer and have identified that the Ca²⁺/Mg²⁺ ratio could be essential for the initiation/progression of prostate cancer.

Biomarkers in prostate cancer epidemiology

Understanding the etiology of a disease such as prostate cancer may help in identifying populations at high risk, timely intervention of the disease, and proper treatment. Biomarkers, along with exposure history and clinical data, are useful tools to achieve these goals. Individual risk and population incidence of prostate cancer result from the intervention of genetic susceptibility and exposure. Biochemical, epigenetic, genetic, and imaging biomarkers are used to identify people at high risk for developing prostate cancer. In cancer epidemiology, epigenetic biomarkers offer advantages over other types of biomarkers because they are expressed against a person's genetic background and environmental exposure, and because abnormal events occur early in cancer development, which includes several epigenetic alterations in cancer cells. This article describes different biomarkers that have potential use in studying the epidemiology of prostate cancer. We also discuss the characteristics of an ideal biomarker for prostate cancer, and technologies utilized for biomarker assays. Among epigenetic biomarkers, most reports indicate GSTP1 hypermethylation as the diagnostic marker for prostate cancer; however, NKX2-5, CLSTN1, SPOCK2, SLC16A12, DPYS, and NSE1 also have been reported to be regulated by methylation mechanisms in prostate cancer. Current challenges in utilization of biomarkers in prostate cancer diagnosis and epidemiologic studies and potential solutions also are discussed.