75 cm3 plastic flasks

Patient 3 cell line (P-3) and patient 6 cell line (P-6) were derived from surgical resection samples of acral melanoma from two patients (Supplementary Figure S2). Written informed consent was obtained from the patients. Melanoma specific antigens were detected via western blotting for CD31, CD63, CD166 and CD146 confirmed that the cells were melanocytes (Supplementary Figure S3, Supplementary Figure S6). Tumor tissues were mechanically dissociated with a small tissue chopper prior to sequential enzymatic digestion in 2 mg/ml Collagenase (Sigma-Aldrich, Schnelldorf, Germany) and 1 mg/ml Dispase I (Gibco/Invitrogen, Carlsbad, CA) in DMEM for 30 min at 37°C. Cells were filtered (100 μm cell strainer) to obtain a single cell suspension and re-supplemented by phosphate-buffered saline, thereafter centrifuged at 1000 r.p.m. for 5 minutes. Pellet was re-suspended in DMEM with 10% FBS and then cultured in 75 cm³ plastic flasks (Themo Fisher Scientific, China).

Patient 8 cell line (P8) was derived from surgical resection samples of acral MM from a patient. Written informed consent was obtained from the patient. P8 cell line was cultured in DMEM medium (BI, China) supplemented with 10% FBS (Gibco, Life Technologies Australia) at 37°C and 5% CO₂ in tissue culture incubator. MM specific antigens were detected via western blotting for CD31, CD63, CD166 and CD146 confirmed that the cells were melanocytes. Tumor tissues were mechanically dissociated with a small tissue chopper prior to sequential enzymatic digestion in 2 mg/ml Collagenase (Sigma-Aldrich, Schnelldorf, Germany) and 1 mg/ml Dispase I (Gibco/Invitrogen, Carlsbad, CA) in DMEM for 30min at 37°C. Cells were filtered (100 μm cell strainer) to obtain a single cell suspension and re-supplemented by phosphate-buffered saline, thereafter centrifuged at 1000 r.p.m. for 5 minutes. Pellet was re-suspended in DMEM with 10% FBS and then cultured in 75 cm³ plastic flasks (Themo Fisher Scientific, China).