Association of genetic variants in JAK/STAT signaling pathway with cutaneous melanoma susceptibility

Janus kinase signal transducer and activator of transcription (JAK/STAT) signaling pathway is involved in cell proliferation, angiogenesis, apoptosis inhibition, metastasis, and immune suppression. Due to these multiple functions, this pathway regulates cutaneous melanoma (CM) development and progression. The JAK1, JAK2 and STAT3 proteins are encoded by polymorphic genes. This study aimed to verify whether single-nucleotide variants (SNVs) in JAK1 (c.1648+1272G>A, c.991-27C>T), JAK2 (c.-1132G>T, c.-139G>A) and STAT3 (c.*1671T>C, c.-1937C>G) altered risk, clinicopathological aspects, survival of CM patients, as well as protein activity. CM patients (N = 248) and controls (N = 274) were included in this study. Genotyping was performed by real-time polymerase chain reaction (PCR) and JAK1, JAK2 and STAT3 expression was assessed by quantitative PCR (qPCR). STAT3 c.-1937C>G SNV was investigated by luciferase, qPCR, western blot, apoptosis, and cell cycle assays in SKMEL-28 cells with CC or GG genotype. In addition, fourteen melanoma cell lines with different genotypes were used to analyze STAT3 expression with non-intervention. Individuals with STAT3 c.*1671TT and c.-1937CC genotypes, and TC haplotype of both SNVs were under 2.0-fold increased risk of CM. Specific JAK1, JAK2 and STAT3 combined genotypes were associated with up to 4.0-fold increased risk of CM. Higher luciferase activity (4,013.34 vs. 2,463.32 arbitrary unit (AU); p = 0.009), STAT3 expression by qPCR (649.20 vs. 0.04 AU; p = 0.003) and western blot (1.69 vs. 1.16 AU; p = 0.01), and percentage of cells in S phase of cell cycle (57.54 vs. 30.73 %; p = 0.04) were more frequent in SKMEL-28 with STAT3 c.-1937CC than with GG genotype. CM cell lines with CC genotype presented higher STAT3 protein levels than those with GG genotype (1.93 versus 1.27 AU, p = 0.0027). Our data present for the first-time preliminary evidence that JAK1, JAK2 and STAT3 SNVs alter risk and clinical aspects of CM patients. If validated in a further epidemiological study, our data can be used to select individuals at high-risk of CM, who should receive special attention in tumor prevention and early detection.