A study of molecular signals deregulating mismatch repair genes in prostate cancer compared to benign prostatic hyperplasia.
Prostate cancer is one of the leading causes of mortality among aging males. There is an unmet requirement of clinically useful biomarkers for early detection of prostate cancer to reduce the liabilities of overtreatment and accompanying morbidity. The present population-based study investigates the factors disrupting expression of multiple functionally related genes of DNA mismatch repair pathway in prostate cancer patients to identify molecular attributes distinguishing adenocarcinoma from benign hyperplasia of prostate. Gene expression was compared between tissue samples from prostate cancer and benign prostatic hyperplasia using real-time-PCR, western blot and immunohistochemistry. Assessment of genotypes of seven single-nucleotide-polymorphisms of three MMR genes was conducted using PCR-coupled RFLP and sequencing. Promoter methylation was interrogated by methylation-specific-PCR and bisulfite-sequencing. Interaction between microRNAs and MMR genes was verified by 3'UTR-based dual luciferase assays. Concurrent reduction of three MMR genes namely hMLH1, hMSH6 and hMSH2 (34-85%, P<0.05) was observed in prostate cancer tissues. hMSH6 polymorphism rs1800932(Pro92Pro) conferred a borderline protection in cancer patients (OR = 0.33, 95% CI = 0.15-0.75). Relative transcript level of hMLH1 was inversely related (r = -0.59, P<0.05) with methylation quotient of its promoter which showed a significantly higher methylation density (P = 0.008, Z = -2.649) in cancer patients. hsa-miR-155, hsa-miR-141 and hsa-miR-21 gene expressions were significantly elevated (66-85%, P<0.05) in tumor specimens and negatively correlated (r = -0.602 to -0.527, P<0.05) with that of MMR genes. hsa-miR-155 & hsa-miR-141 and hsa-miR-155 & hsa-miR-21 were demonstrated to bind to their putative seed sequences in hMLH1 and hMSH6 3'UTRs respectively. Relatively higher expression of DNA methyl-transferases (DNMT1 and DNMT3b) and HIF-1α genes (34-50%, P<0.05) were also detected in tumor tissues. This study provides statistical evidence that MMR deficiency is correlated with hypermethylation of hMLH1 promoter and upregulation of hsa-miR-155, hsa-miR-141 and hsa-miR-21 in prostate cancer. This comparative study reflects that microRNA expression level, particularly hsa-miR-155, exhibits predictive signature of prostate adenocarcinoma.
Department of Biochemistry, University of Calcutta, Kolkata, West Bengal, India.
Sanmitra
S
Basu
Department of Biochemistry, University of Calcutta, Kolkata, West Bengal, India.
Subhadipa
S
Majumder
Department of Biochemistry, University of Calcutta, Kolkata, West Bengal, India.
Ankur
A
Bhowal
Centre for Liver Research, Institute of Post-Graduate Medical Education & Research, Kolkata, West Bengal, India.
Alip
A
Ghosh
Department of Pathology, Calcutta National Medical College & Hospital, Kolkata, West Bengal, India.
Sukla
S
Naskar
Department of Pathology, Calcutta National Medical College & Hospital, Kolkata, West Bengal, India.
Sumit
S
Nandy
Department of Urology, Calcutta National Medical College & Hospital, Kolkata, West Bengal, India.
Subhabrata
S
Mukherjee
Department of Urology, Calcutta National Medical College & Hospital, Kolkata, West Bengal, India.
Rajan Kumar
RK
Sinha
Department of Pathology, Calcutta National Medical College & Hospital, Kolkata, West Bengal, India.
Keya
K
Basu
Department of Urology, Calcutta National Medical College & Hospital, Kolkata, West Bengal, India.
Dilip
D
Karmakar
Centre for Liver Research, Institute of Post-Graduate Medical Education & Research, Kolkata, West Bengal, India.
Soma
S
Banerjee
Department of Biochemistry, University of Calcutta, Kolkata, West Bengal, India.
Sanghamitra
S
Sengupta
D020413:3' Untranslated Regions; D000368:Aged; D000483:Alleles; D001483:Base Sequence; D001665:Binding Sites; D014408:Biomarkers, Tumor; D018899:CpG Islands; D019175:DNA Methylation; D053843:DNA Mismatch Repair / Q000235:genetics*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D008297:Male; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics; D008875:Middle Aged; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011470:Prostatic Hyperplasia / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism*; D034622:RNA Interference; D017422:Sequence Analysis, DNA; D015398:Signal Transduction
D020413:3' Untranslated Regions; D014408:Biomarkers, Tumor; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D035683:MicroRNAs