Mutational landscape of oral mucosal melanoma based on comprehensive cancer genomic profiling tests in a Japanese cohort.

OBJECTIVES: Oral mucosal melanoma (OMM) is a rare but aggressive melanoma subtype. Due to its rarity, the genomic landscape of OMM remains unknown despite a relatively thorough understanding of the genetic profile of cutaneous melanoma (CM). In this study, we analyzed the genomic mutational profiles of Japanese patients with OMM and compared them with those of patients with nose/sinuses mucosal melanoma (NMM) and CM to identify potential therapeutic targets. MATERIALS AND METHODS: We extracted clinical and genomic information of patients with OMM (n = 15), NMM (n = 63), and CM (n = 413) who underwent comprehensive genomic profiling tests under the National Health Insurance between June 2019 and November 2023 from the Center for Cancer Genomics and Therapeutics database. RESULTS: The most frequent genomic alteration identified in OMM was RICTOR (40%) followed by CDK4 (33.3%), MDM2 (33.3%), KDR (30%), KIT (26.7%), and NF1 (26.7%). CDK4 and MDM2 were co-amplified. Gene alterations in MYC and NRAS were the highest in patients with NMM, followed by those with CM, and no MYC alteration was observed in patients with OMM. BRAF V600 mutation, which is frequently observed in patients with CM (23.2%) were only present in 1.6% of patients with NMM and none in patients with OMM. CONCLUSION: This study clarified the genetic differences between OMM and NMM, and the first to report the frequent occurrence of RICTOR amplification in OMM. This analysis offers insights into the development of personalized therapeutics for OMM.

Transcriptomic profiling of single circulating tumor cells provides insight into human metastatic gastric cancer.

Transcriptome analysis of circulating tumor cells (CTCs), which migrate into blood vessels from primary tumor tissues, at the single-cell level offers critical insights into the biology of metastasis and contributes to drug discovery. However, transcriptome analysis of single CTCs has only been reported for a limited number of cancer types, such as multiple myeloma, breast, hepatocellular, and prostate cancer. Herein, we report the transcriptome analysis of gastric cancer single-CTCs. We utilized an antigen-independent strategy for CTC isolation from metastatic gastric cancer patients involving a size-dependent recovery of CTCs and a single cell isolation technique. The transcriptomic profile of single-CTCs revealed that a majority of gastric CTCs had undergone epithelial-mesenchymal transition (EMT), and indicated the contribution of platelet adhesion toward EMT progression and acquisition of chemoresistance. Taken together, this study serves to employ CTC characterization to elucidate the mechanisms of chemoresistance and metastasis in gastric cancer.