Down-regulated Expression of the S100 Gene Family Members in OSCCs

Objectives: To examine the expression profile of 16 members (S100A1, A2, A3, A4, A6, A7, A8, A9, A10, A11, A12, A13, A14, B, P and Z) of the S100 gene family at the mRNA level by semiquantitative reverse transcription-polymerase chain reaction (sRT-PCR) in 27 cases of oral squamous cell carcinomas (OSCCs)/their pair-wised normal controls obtained from Sudanese patients, and to confirm the sRT-PCR results by performing quantitative real time-polymerase chain reaction (qRT-PCR) for 6 of the 16 genes examined.

Methods: Total RNA was extracted, quantified and quality assured from all the OSCCs/normal controls, followed by cDNA synthesis and RT-PCR. Gel electrophoretic images of the sRT-PCR were captured with Gel Doc XR (Bio-Rad) and the intensities of the bands were analyzed with Quantity one software (Bio-Rad). For the 6 genes examined by qRT-PCR (ABI Prism Sequence Detector 7900 HT, Applied Biosystems) relative standard curve method was used to quantify the mRNA level. GAPDH was used as an endogenous control for both sRT-PCR and qRT-PCR. Wilcoxon matched-pair signed rank test was thereafter used for the statistical analysis. P< 0.05 was considered as statistical significant.

Results: With sRT-PCR, 4 (25%; S100A4, S100A6, S100A8, S100A14) out of the 16 S100 gene members examined were found to be significantly down-regulated (P< 0.05) in the tumors compared to the controls. None of the S100 gene members examined were found to be significantly up-regulated in the tumors. qRT-PCR results confirmed the significant down-regulation of the S100A4, S100A6 and S100A14 in the tumors examined.

Conclusions: S100 gene family members might play an important role in the pathogenesis of the OSCCs examined. Findings of the present work warrant in-depth studies of the S100 gene family members, in particular, the S100A4, S100A6, S100A8 and S100A14 to further understand their possible role(s) in OSCC carcinogenesis.