Expression of apoptosis-regulating miRNAs and target mRNAs in oral squamous cell carcinoma

Aberrations in the apoptotic mechanisms that cause excessive or deficient programmed cell death have been linked to a wide array of pathological conditions. In this study, using real-time reverse transcriptase–PCR, we analyzed the expression of apoptosis-regulating miRNAs (miR-15a, miR-16, miR-17-5p, miR-20a, miR-21, miR-29a, and miR-34a) in 20 oral squamous cell carcinoma and 5 normal oral mucosa tissue samples. Bioinformatic algorithms were used to identify the target genes of these miRNAs (BCL2, CASP2, CASP7, CASP8, DIABLO). The expression transcript levels of the target genes were measured in 50 oral squamous cell carcinoma and 10 normal oral mucosa tissue samples. We observed downregulation of miR-15a, miR-29a, and miR-34a in 50, 75, and 70% of samples, respectively. miR-16, miR-17-5p, miR-20a, and miR-21 expression was normal in 80, 75, 90, and 60% of samples, respectively. BCL2 transcripts were downregulated in 60% of samples, and normal-like expression was observed for CASP2, CASP7, CASP8, and DIABLO transcripts in 66, 82, 68, and 60% of samples, respectively. BCL2 expression was negative to weak, and that of proteins CASP2, CASP7, CASP8, and DIABLO was moderate to strong. Our study provides evidence of alterations in the expression of apoptosis-regulating miRNAs and genes in the apoptotic pathway, demonstrating that regulation of apoptosis is a hallmark of oral squamous cell carcinoma pathogenesis.