Approximately one-half of advanced (unresectable or metastatic) melanomas harbor a mutation in the BRAF gene, with V600E being the most common mutation.,Targeted therapy with BRAF and MEK inhibitors is associated with significant long-term treatment benefit in patients with BRAF V600-mutated melanoma.,Therefore, molecular testing for BRAF mutations is a priority in determining the course of therapy.,A literature search was performed using MEDLINE/PubMed and scientific congress databases using the terms ‘BRAF,’ ‘mutation,’ and ‘cancer/tumor.’,These results were filtered to include manuscripts that focused on diagnostic tests for determining BRAF mutation status.,Numerous BRAF testing methods were identified, including DNA-based companion diagnostic tests and DNA- and protein-based laboratory-developed tests.,Herein we review the characteristics of each method and highlight the strengths and weaknesses that should be considered before use and when interpreting results for each patient.,Molecular profiling has shown that mutation load increases with melanoma tumor progression and that unique patterns of genetic changes and evolutionary trajectories for different melanoma subtypes can occur.,Discordance in the BRAF mutational status between primary and metastatic lesions, as well as intratumoral heterogeneity, is known to occur.,Additionally, the development of acquired resistance to combination BRAF and MEK inhibitor therapy is still a formidable obstacle.,Therefore, tumor heterogeneity and the development of acquired resistance have important implications for molecular testing and ultimately the treatment of patients with advanced-stage melanoma.,Overall, this information may help community oncologists more accurately and effectively interpret results of diagnostic tests within the context of recent data characterizing melanoma tumor progression.
The immediate molecular mechanisms behind invasive melanoma are poorly understood.,Recent studies implicate microRNAs (miRNAs) as important agents in melanoma and other cancers.,To investigate the role of miRNAs in melanoma, we subjected human melanoma cell lines to miRNA expression profiling, and report a range of variations in several miRNAs.,Specifically, compared with expression levels in melanocytes, levels of miR-211 were consistently reduced in all eight non-pigmented melanoma cell lines we examined; they were also reduced in 21 out of 30 distinct melanoma samples from patients, classified as primary in situ, regional metastatic, distant metastatic, and nodal metastatic.,The levels of several predicted target mRNAs of miR-211 were reduced in melanoma cell lines that ectopically expressed miR-211.,In vivo target cleavage assays confirmed one such target mRNA encoded by KCNMA1.,Mutating the miR-211 binding site seed sequences at the KCNMA1 3′-UTR abolished target cleavage.,KCNMA1 mRNA and protein expression levels varied inversely with miR-211 levels.,Two different melanoma cell lines ectopically expressing miR-211 exhibited significant growth inhibition and reduced invasiveness compared with the respective parental melanoma cell lines.,An shRNA against KCNMA1 mRNA also demonstrated similar effects on melanoma cells. miR-211 is encoded within the sixth intron of TRPM1, a candidate suppressor of melanoma metastasis.,The transcription factor MITF, important for melanocyte development and function, is needed for high TRPM1 expression.,MITF is also needed for miR-211 expression, suggesting that the tumor-suppressor activities of MITF and/or TRPM1 may at least partially be due to miR-211's negative post transcriptional effects on the KCNMA1 transcript.,Given previous reports of high KCNMA1 levels in metastasizing melanoma, prostate cancer and glioma, our findings that miR-211 is a direct posttranscriptional regulator of KCNMA1 expression as well as the dependence of this miRNA's expression on MITF activity, establishes miR-211 as an important regulatory agent in human melanoma.