GNAQ and GNA11 somatic mutations in uveal melanoma in Japanese patients and their relationship with cell type or proliferation activity

Abstract

Purpose : To examine whether GNAQ and GNA11 somatic mutations are associated with uveal melanoma in Japanese patients and to evaluate their relationship with cell types or Ki67 labeling index.

Methods : This study is single-institution study and includes 19 cases of uveal melanoma. All 19 eyeballs were enucleated and diagnosed with uveal melanoma using histopathological examination. DNA template was extracted from formalin-fixed paraffin-embedded specimens. We amplified DNA area of GNAQ and GNA11 using PCR method, and analyzed mutation by direct sequencing. Cell types were classified into three groups: spindle, epithelioid and mixed types. Ki67 labeling index was evaluated by immunofluorescence staining.

Results : The frequency of GNAQ and GNA11 somatic mutations in Japanese uveal melanoma was 26.3% (5/19) and 31.6% (6/19), respectively. The mutation occurred exclusively in those areas. The frequency of GNA11 mutation was significantly high in epithelioid type (p=0.04). There was no statistical significant association between GNAQ mutation and cell type (p=0.78). In addition, there was no significant difference in Ki67 labeling index between the mutation-positive and mutation-negative eyeballs (p=0.62).

Conclusions : The mutation of GNAQ and GNA11 that can be found in Japanese patients with uveal melanoma is similar to the one in Caucasian patients. According to previous reports concerning Caucasian patients, there was no relationship between mutation and cell type, so there is a vivid difference between Japanese and Caucasian patients in this regard.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.