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.