Increase of ZASC1 gene copy number in recurrent oral carcinoma: ZASC1 and oral cancer recurrence

Backgrounds: The chromosome 3q26 locus is a hotspot region carrying oncogenes that frequently altered in neoplasms. ZASC1 is a zinc finger protein transcription factor localized on 3q26. Our previous study showed the frequent amplification of 3q26, including the ZASC1 gene, in oral squamous cell carcinoma (OSCC). This study investigated the copy number changes of ZASC1 gene from primary to recurrent OSCC and the functions of ZASC1 in OSCC cells. Materials and methods: A total of 27 OSCC patients with primary and recurrent tumors were examined for ZASC1 and TERC copy number changes using Quantitative PCR analysis. Exogenous expression and knockdown of ZASC1 were carried out to specify the oncogenic potential of ZASC1 in OSCC cells. Results: A ZASC1 copy number that has increased from primary to recurrent tumor counterparts in tissue pairs suggested the importance of ZASC1 in tumor progression. The increase of ZASC1 gene copy number in recurrent tumors was associated with the consumption of betel quid in patients. OSCC cells expressing ZASC1-FLAG fusion protein showed increased proliferation. After the knockdown of endogenous ZASC1 expression using small interference RNA, the growth and colony formation of SAS OSCC cells decreased. Conclusions: The findings support the hypothesis that ZASC1 localized on 3q26 contributes to the recurrence of OSCC.