How many copies of GSTM1 and GSTT1 are associated with head and neck cancer risk?

Abstract

Purpose: GSTM1 and GSTT1 present a polymorphism that can drive complete gene deletions. The current methodology can powerfully determine GSTM1 and GSTT1 copy number variations (CNVs), which may clarify the real contribution of each gene copies to the cellular detoxification process and tumour risk. However, only analysing the presence/absence of these genes yielded controversial results for several disorders, including cancer. Because head and neck cancer (HNC) is becoming a serious global health problem, this study determined the CNVs of GSTM1 and GSTT1 in an HNC case-control population and investigated the possible association between gene copy numbers and tumour risk.

Methods: CNV was evaluated by (Ct) 2^−ΔΔCt qPCR methodology in 619 HNC patients and 448 patients with no tumour diagnosis.

Results: The genes copy number range was 0–3. The CNV of GSTM1 and GSTT1 frequencies were similar between the cases and control. Thus, none copy of GSTM1 and GSTT1 were associated with HNC risk. Notwithstanding, one copy of both genes had higher frequencies among individuals who carried GSTM1 and GSTT1.

Conclusions: One copy number of GSTM1 and GSTT1 presented a higher frequency among carrier genes, but the CNV of GSTM1 and GSTT1 was not associated with HNC risk.

Keywords:

• Copy number variation
• GSTM1
• GSTT1
• head and neck cancer
• cancer susceptibility
• cellular detoxification

Disclosure statement

The authors report no conflicts of interest.

Additional information

Funding

This work was supported by São Paulo Research Foundation under Grant 2014/16092-4 and Fundação de Amparo à Pesquisa do Estado de São Paulo.