Neuroblastoma rat-sarcoma viral oncogene homolog (NRAS) isoforms are expressed in melanoma tumor tissues, which have been described in Caucasian melanoma. However, the status and the clinical significance of NRAS isoforms in the Asian population have not been investigated on a large scale. We examined the expression levels of NRAS isoforms of 140 melanoma samples using quantitative real-time PCR. Furthermore, the relationship of mRNA expression of NRAS isoforms to clinicopathological characteristics and survival of patients was analyzed. Statistical analysis showed that NRAS isoform 2 expression was correlated with melanoma subtypes (P=0.007), and NRAS isoform 4 expression was correlated with tumor thickness (P=0.031) and clinical stage (P=0.006). The median overall survival for patients with high expression of NRAS isoform 3 was significantly shorter than that for patients with low expression of NRAS isoform 3 (P=0.007). In addition, high expression of NRAS isoform 5 was associated with a worse prognosis (P=0.049 and 0.002 for overall survival and disease-free survival, respectively). Multivariate Cox regression analysis showed that high expression levels of NRAS isoform 3 and isoform 5 were independent poor prognostic factors for patients. Our results indicated that the mRNA expressions of NRAS isoform 3 and isoform 5 may be novel indicators of the prognosis of Chinese melanoma patients.
aDepartment of Oncology, Henan Provincial People’s Hospital, Zhengzhou
bKey Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Beijing, China
*Junya Yan and Longwen Xu contributed equally to the writing of this article.
Correspondence to Yan Kong, PhD, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, No. 52 Fucheng Road, Haidian District, Beijing 100142, China Tel: +86 108 819 6707; fax: +86 108 819 6317; e-mail: firstname.lastname@example.org
Received August 9, 2018
Accepted October 31, 2018