Association of calcium sensing receptor polymorphisms at rs1801725 with circulating calcium in breast cancer patients

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.

Haplotype of CaSR gene is associated with risk of renal stone disease in West Indian population

Calcium is the most abundant metabolite involved in the stone matrix. The CaSR gene controls calcium homeostasis, and genetic variation in the CaSR gene could lead to the development of renal stone disease. Therefore, the current study has been designed to assess the association of genetic variants of CaSR gene polymorphisms with renal stone disease. A single-centric prospective study has been carried out on a total of 300 participants (150 cases and 150 controls). Serum levels of calcium, creatinine, parathyroid hormone, and 24 h urine metabolites were measured. Two polymorphisms, rs1801725 and rs1042636, of the CaSR gene, have been genotyped for each participant. T test, binary logistic regression, and Chi-square analysis were used for statistical analysis. Renal stone patients had significantly higher levels of serum parathyroid hormone, creatinine, and 24-h urine metabolites in comparison to the controls. CaSR gene variants, rs1801725 (GG) and rs1042636 (AA), both have shown significant association with renal stone disease. In addition, individuals having specific genotypes along with metabolic abnormalities such as hypercalcemia and hyperparathyroidism are found to be at a higher significant risk of developing the renal stone disease. In the present study, the haplotype of the CaSR gene has shown an association with renal stone disease. Individuals with hyperparathyroidism and hypercalcemia and risk genotype have a higher susceptibility to developing renal stone disease.

Association of TRPV5, CASR, and CALCR genetic variants with kidney stone disease susceptibility in Egyptians through main effects and gene–gene interactions

Kidney stone disease (KSD) represents an urgent medical problem because of increasing its prevalence. Several functional polymorphisms in genes involved in the renal handling of calcium were associated with KSD pathogenesis. Among those, the rs4236480 of transient receptor potential vanilloid member 5 (TRPV5) gene, the rs1801725 of calcium-sensing receptor (CASR) gene, and the rs1801197 of calcitonin receptor (CALCR) gene appear to be of great importance. Due to the scarce data on the Egyptians, this study aimed to evaluate the association of these candidate genetic variants with the risk of developing KSD in an Egyptian population. To do so, the biochemical parameters were measured along with the genotyping of the three polymorphisms using allelic discrimination assay in 134 KSD patients and 86 age and sex-matched healthy subjects. The results showed that the genotypic distributions and allelic frequencies of the studied variants were significantly different between cases and controls. The three polymorphisms increased the risk of KSD significantly under all the tested genetic models (OR ranges from 2.152 to 5.994), except for the recessive model of the CALCR rs1801197 polymorphism after Bonferroni correction. The gene–gene interaction analyzed by multifactor dimensionality reduction selected the three-locus combination as the best model associated with the susceptibility to KSD with OR 9.706. Further, synergistic interactions were identified between TRPV5 rs4236480 and CALCR rs1801197 variants and CASR rs1801725 and CALCR rs1801197 variants. In conclusion, the TRPV5 rs4236480, CASR rs1801725, and CALCR rs1801197 polymorphisms showed a significant association with the risk of KSD in the Egyptian population. Furthermore, their complex interactions might have an impact on the genetic susceptibility to develop KSD.

Identification of MAGEC2/CT10 as a High Calcium-Inducible Gene in Triple-Negative Breast Cancer

The expression of the melanoma/cancer-testis antigen MAGEC2/CT10 is restricted to germline cells, but like most cancer-testis antigens, it is frequently upregulated in advanced breast tumors and other malignant tumors. However, the physiological cues that trigger the expression of this gene during malignancy remain unknown. Given that malignant breast cancer is often associated with skeletal metastasis and co-morbidities such as cancer-induced hypercalcemia, we evaluated the effect of high Ca²⁺ on the calcium-sensing receptor (CaSR) and potential mechanisms underlying the survival of triple-negative breast cancer (TNBC) cells at high Ca²⁺. We show that chronic exposure of TNBC cells to high Ca²⁺ decreased the sensitivity of CaSR to Ca²⁺ but stimulated tumor cell growth and migration. Furthermore, high extracellular Ca²⁺ also stimulated the expression of early response genes such as FOS/FOSB and a unique set of genes associated with malignant tumors, including MAGEC2. We further show that the MAGEC2 proximal promoter is Ca²⁺ inducible and that FOS/FOSB binds to this promoter in a Ca²⁺- dependent manner. Finally, downregulation of MAGEC2 strongly inhibited the growth of TNBC cells in vitro. These data suggest for the first time that MAGEC2 is a high Ca²⁺ inducible gene and that aberrant expression of MAGEC2 in malignant TNBC tissues is at least in part mediated by an increase in circulating Ca²⁺via the AP-1 transcription factor.

Polymorphisms Contributing to Calcium Status: A Systematic Review

This systematic review assessed genotypes and changes in calcium homeostasis. A literature search was performed in EMBASE, Medline and CENTRAL on 7 August 2020 identifying 1012 references. Studies were included with any human population related to the topic of interest, and genetic variations in genes related to calcium metabolism were considered. Two reviewers independently screened references, extracted relevant data and assessed study quality using the Q-Genie tool. Forty-one studies investigating Single Nucleotide Polymorphisms (SNPs) in relation to calcium status were identified. Almost half of the included studies were of good study quality according to the Q-Genie tool. Seventeen studies were cross-sectional, 14 case-control, seven association and three were Mendelian randomization studies. Included studies were conducted in over 18 countries. Participants were mainly adults, while six studies included children and adolescents. Ethnicity was described in 31 studies and half of these included Caucasian participants. Twenty-six independent studies examined the association between calcium and polymorphism in the calcium-sensing receptor (CASR) gene. Five studies assessed the association between polymorphisms of the Vitamin D receptor (VDR) gene and changes in calcium levels or renal excretion. The remaining ten studies investigated calcium homeostasis and other gene polymorphisms such as the CYP24A1 SNP or CLDN14. This study identified several CASR, VDR and other gene SNPs associated with calcium status. However, to provide evidence to guide dietary recommendations, further research is needed to explore the association between common polymorphisms and calcium requirements.

Calcium-Sensing Receptor Polymorphisms at rs1801725 Are Associated with Increased Risk of Secondary Malignancies

Dysregulation of systemic calcium homeostasis during malignancy is common in most patients with high-grade tumors. However, it remains unclear whether single nucleotide polymorphisms (SNPs) that alter the sensitivity of the calcium-sensing receptor (CaSR) to circulating calcium are associated with primary and/or secondary neoplasms at specific pathological sites in patients of European and African ancestry. Multivariable logistic regression models were used to analyze the association of CASR SNPs with circulating calcium, parathyroid hormone, vitamin D, and primary and secondary neoplasms. Circulating calcium is associated with an increased risk for breast, prostate, and skin cancers. In patients of European descent, the rs1801725 CASR SNP is associated with bone-related cancer phenotypes, deficiency of humoral immunity, and a higher risk of secondary neoplasms in the lungs and bone. Interestingly, circulating calcium levels are higher in homozygous patients for the inactivating CASR variant at rs1801725 (TT genotype), and this is associated with a higher risk of secondary malignancies. Our data suggest that expression of CaSR variants at rs1801725 is associated with a higher risk of developing secondary neoplastic lesions in the lungs and bone, due in part to cancer-induced hypercalcemia and/or tumor immune suppression. Screening of patients for CASR variants at this locus may lead to improved management of high calcium associated tumor progression.

Rare diseases caused by abnormal calcium sensing and signalling

The calcium-sensing receptor (CaSR) provides the major mechanism for the detection of extracellular calcium concentration in several cell types, via the induction of G-protein-coupled signalling. Accordingly, CaSR plays a pivotal role in calcium homeostasis, and the CaSR gene defects are related to diseases characterized by serum calcium level changes. Activating mutations of the CaSR gene cause enhanced sensitivity to extracellular calcium concentration resulting in autosomal dominant hypocalcemia or Bartter-syndrome type V. Inactivating CaSR gene mutations lead to resistance to extracellular calcium. In these cases, familial hypocalciuric hypercalcaemia (FHH1) or neonatal severe hyperparathyroidism (NSHPT) can develop. FHH2 and FHH3 are associated with mutations of genes of partner proteins of calcium signal transduction. The common polymorphisms of the CaSR gene have been reported not to affect the calcium homeostasis itself; however, they may be associated with the increased risk of malignancies.

The CaSR in Pathogenesis of Breast Cancer: A New Target for Early Stage Bone Metastases

The Ca2+-sensing receptor (CaSR) is a class-C G protein-coupled receptor which plays a pivotal role in calciotropic processes, primarily in regulating parathyroid hormone secretion to maintain systemic calcium homeostasis. Among its non-calciotropic roles, where the CaSR sits at the intersection of myriad processes, it has steadily garnered attention as an oncogene or tumor suppressor in different organs. In maternal breast tissues the CaSR promotes lactation but in breast cancer it acts as an oncoprotein and has been shown to drive the pathogenesis of skeletal metastases from breast cancer. Even though research has made great strides in treating primary breast cancer, there is an unmet need when it comes to treatment of metastatic breast cancer. This review focuses on how the CaSR leads to the pathogenesis of breast cancer by contrasting its role in healthy tissues and tumorigenesis, and by drawing brief parallels with the tissues where it has been implicated as an oncogene. A class of compounds called calcilytics, which are CaSR antagonists, have also been surveyed in the instances where they have been used to target the receptor in cancerous tissues and constitute a proof of principle for repurposing them. Current clinical therapies for treating bone metastases from breast cancer are limited to targeting osteoclasts and a deeper understanding of the CaSR signaling nexus in this context can bolster them or lead to novel therapeutic interventions.

Calcium-sensing receptor gene (CASR) polymorphisms and CASR transcript level concerning dyslipidemia in hemodialysis patients: a cross-sectional study

BACKGROUND

There is scarce data on CASR associations with dyslipidemia. We investigated in hemodialysis (HD) patients whether CASR single nucleotide polymorphisms (SNPs) rs7652589 and rs1801725 have associations with dyslipidemia and show epistatic interactions with SNPs of the energy homeostasis-associated gene (ENHO), retinoid X receptor α gene (RXRA), and liver X receptor α gene (LXRA).

METHODS

The study included 1208 HD subjects. For diagnosis of dyslipidemia, both K/DOQI criteria and atherogenic index ≥3.8 were used. CASR rs1801725 was genotyped by TaqMan SNP Genotyping Assay, other SNPs - by high-resolution melting curve analysis or polymerase chain reaction-restriction fragment length polymorphism, as appropriate. Relative transcript levels of CASR, ENHO, RXRA, and LXRA were measured in peripheral blood mononuclear cells. The occurrence of dyslipidemic phenotypes concerning tested polymorphisms was compared using models of inheritance. Haplotypes were estimated using the Haploview 4.2 software. Epistatic interactions between tested SNPs were analyzed using the logistic regression and epistasis option in the PLINK software.

RESULTS

Rs7652589 indicated a greater probability of atherogenic dyslipidemia in the dominant inheritance model (OR 1.4, 95%CI 1.0-2.0, P = 0.026), principally because of increased triglyceride (TG) levels. The rs1801725 variant allele was associated with a decreased probability of dyslipidemia characterized by non-HDL-cholesterol ≥130 mg/dL and TG ≥200 mg/dL (OR 0.6, 0.4-0.9, P = 0.012). There were no epistatic interactions between CASR and RXRA, LXRA, and ENHO regarding dyslipidemia. Both rs7652589 and rs1801725 SNPs were not in linkage disequilibrium (D' = 0.091, r² = 0.003 for the entire HD group) and their haplotypes did not correlate with dyslipidemia. Relative CASR transcript was lower at a borderline significance level in patients harboring the rs1801725 variant allele compared with homozygotes of the major allele (0.20, 0.06-7.80 vs. 0.43, 0.04-5.06, P = 0.058). CASR transcript correlated positively with RXRA transcript (adjusted P = 0.001), LXRA transcript (adjusted P = 0.0009), ENHO transcript (borderline significance, adjusted P = 0.055), dry body weight (adjusted P = 0.035), and renal replacement therapy duration (adjusted P = 0.013).

CONCLUSIONS

CASR polymorphisms (rs7652589, rs1801725) are associated with dyslipidemia in HD patients. CASR correlates with RXRA, LXRA, and ENHO at the transcript level. Further investigations may elucidate whether other CASR SNPs contribute to associations shown in this study.

Genetic variants of calcium sensing receptor gene and risk of colorectal cancer: A case-control study

Objectives:

To determine the role of two genetic variants, (rs3804594) and (rs1801725), in calcium sensing receptor (CASR) gene with colorectal cancer (CRC) risk in patients visited King Abdulaziz University hospital (KAUH) in Jeddah, Saudi Arabia.

Methods:

Genomic DNA was extracted, by commercial DNA extraction kit, from whole blood of 100 CRC patients and 124 controls who visited KAUH from January 2016 to September 2016. Then genotype and allele distributions of both variants were determined by PCR-RFLP and DNA sequencing techniques. All statistical analyses were performed by unpaired t-test and P-values <0.05 were considered statistically significant.

Results:

Data obtained from χ² test showed that intron 4 variant in CASR gene was distributed 100% normally in the 224 participants, however, exon 7 variant showed 100% homozygous distribution in the controls; whereas, in CRC patients it was distributed equally into 50% heterozygous and 50% homozygous with no detection for wild type.

Conclusion:

Intron 4 variant (rs3804594) in CASR gene is not correlated to CRC risk. However, more investigations are needed to elucidate the role of CASR gene exon 7 (rs1801725) variant in CRC development as the current results are not definitive.

The Calcium-Sensing Receptor Gene Polymorphism rs1801725 and Calcium-Related Phenotypes in Hemodialysis Patients

BACKGROUND/AIMS

The calcium-sensing receptor gene (CASR) rs1801725 variant is responsible for a non-conservative amino-acid change (A986S) in the calcium-sensing receptor cytoplasmic tail. We hypothesized that rs1801725 polymorphism might be helpful in understanding Ca-related abnormalities in HD patients.

METHODS

In 1215 subjects (245 on cinacalcet), we determined the associations of rs1801725 with secondary hyperparathyroidism (sHPT)-related laboratory parameters, PTH-decreasing effect of cinacalcet hydrochloride, coronary artery disease (CAD), myocardial infarction (MI), nephrolithiasis-related ESRD, and mortality. CASR rs7652589(AT) haplotypes and rs1801725 epistatic interactions with vitamin D signaling pathway genes were examined for associations with selected phenotypes.

RESULTS

The rs1801725 variant allele showed an increasing independent effect on plasma PTH (Pcorrected = 0.009). CASR rs7652589_rs1801725 AT haplotype was associated with 1.7-fold higher frequency of PTH levels over 437 pg/mL than the reference haplotype GG (P = 0.001). CASR rs7652589_rs1801725 AG haplotype was 1.5-fold more frequent in nephrolithiasis-related ESRD than the GG haplotype (P = 0.004). There were no significant associations between rs1801725, CAD, MI, and response to cinacalcet. Variant homozygosity of rs1801725 correlated independently with higher infection-related mortality compared with heterozygosity (HR 7.95, 95%CI 2.15 - 29.37, P = 0.003) and major homozygosity (HR 5.89, 95%CI 1.69 - 20.55, P = 0.040). CASR rs1801725 did not show epistatic interactions with vitamin D signaling pathway genes concerning tested associations.

CONCLUSION

The variant allele of CASR rs1801725 solely and together with the variant allele of rs7652589 increases risk of more advanced sHPT. Homozygosity of the rs1801725 variant allele contributes to infection-related mortality in HD patients.

Review of Polymorphism of the Calcium-Sensing Receptor Gene and Breast Cancer Risk

Polymorphism of the calcium-sensing receptor gene (CaSR or CaR) has been associated with an increased risk for breast cancer. This receptor plays an important role in calcium homeostasis, and has also been detected in several tissues that are unrelated to calcium metabolism, such as the skin, brain, and breast. The calcium-sensing receptor on cellular level, it regulates cell differentiation, proliferation, cell death, and gene expression. In breast cancer cells, CaSR seems to stimulate secretion of the parathyroid hormone-related protein (PTHrP), which stimulates cellular proliferation. Likewise, some studies have supported not only an association between calcium receptor gene polymorphism and breast cancer risk, but also a higher aggressiveness and unfavorable outcomes in breast cancer, which led us to make a survey in Pubmed on the subject in the last 10 years. Thus, in the literature there is a paucity of studies on the subject and the aim of this review was to show the role of calcium-sensing receptor and its association with breast cancer risk.

Genetic polymorphism of calcium-sensing receptor in women with breast cancer

Breast cancer is a disease of unknown etiology, whose major risk factors are genetic alterations. Polymorphism of the calcium-sensing receptor (CaSR) has been a focus of some recent studies, due to a probable association with breast cancer risk and tumor aggressiveness. A relationship between polymorphic rs17251221 variant of the CaSR gene, and allele G (considered a gain-of-function mutation) and breast cancer risk has been stressed, despite the paucity of studies found in the literature. The present study involved 137 women (69 women with breast cancer-case; and 68 controls without breast cancer) who had 3 ml of peripheral blood drawn for DNA study. Genomic DNA was extracted from leukocytes by genotyping technique with real-time polymerase chain reaction. The AG genotype (rs17251221) was present in 13 women (18.84%) from the case group and in 8 (11.76%) women from the control group (p = 0.3434), while the GG genotype (rs17251221) did not occur in any group. In contrast, no statistically significant difference was observed between the AG genotype of variant rs17251221 in premenopausal case and control women (p = 0.71). There was also no statistically significant difference between postmenopausal case and control patients (p = 0.6851). In the current study, CaSR gene polymorphism of SNP variant rs17251221 did not show any statistically significant association with breast cancer, in both premenopausal and postmenopausal women.