ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression and alteration (including homozygous deletion and mutation) of MTS1 gene in precancerous lesions and squamous cell carcinomas (SCC) of oral mucosa, and to analyse the function of MTS1 gene alteration in oral mucosal carcinogenesis.</p><p><b>METHODS</b>The expression of p16 protein produced by MTS1 gene was examined with immunohistochemical SP method in 10 normal oral mucosas, 30 precancerous lesions (10 mild, 10 moderate and 10 severe dysplasia respectively) and 45 squamous cell carcinomas (SCCI18, SCCII 19, SCCIII 8). The deletion and mutation of exon1 and exon2 of MTS1 gene were examined with methods of PCR and SSCP in these same samples.</p><p><b>RESULTS</b>All the precancerous lesions had p16 protein expression and no alteration of MTS1 gene. In SCC, the positive rate of p16 protein was 60.0% with 72.2% in SCCI, 57.9% in SCCII, 37.5% in SCC III, and there were no significant difference among the three groups by chi2 test (P>0.05). Gene homozygous deletion of exon1 and/or exon2 was detected in 10 cases, and gene mutation in 4 cases. The whole rate of gene alteration was 31.1% (14/45). The MTS1 gene alteration rate was 27.8% in SCCI, 31.6% in SCCII, 37.5% in SCC III and there was also no significant difference among the three groups by chi2 test (P>0.05). In SCC with local lymph nodes metastasis, MTS1 alteration rate was 57.1%, while in SCC with no lymph nodes metastasis was 8.3%, and there was significant difference by chi2 test (P<0.05).</p><p><b>CONCLUSIONS</b>MTS1 gene alteration is not an early event in the carcinogenesis of oral mucosa and can not be used as a biology mark to examine oral precancerous lesions. MTS1 gene may play a certain role in the progression of oral squamous cell carcinomas.</p>