Fig. 2.
TYRP1 expression is unaltered at the mRNA level and remains undetectable at the protein level during development of resistance to vemurafenib (PLX) and trametinib (TRA) in BRAFV600E melanoma cells regardless of changes in the MITF-M level. a Representative Western blot images showing comparison of TYRP1 and MITF-M protein levels in drug-naïve (–) vs. vemurafenib-resistant (PLXR) cell lines. The levels of TYRP1 and MITF-M in vemurafenib-resistant melanoma cells subjected to drug discontinuation (‘drug holiday’; PLXR DH) are included. GAPDH was used as a loading control. DMBC17 cell lysate was used in parallel as a positive control for TYRP1 and MITF-M staining. b Comparison of expression of TYRP1, SLC45A2, BIRC7 and BCL2A1 in vemurafenib-resistant BRAFV600E melanoma cell lines either exposed to drug or after drug discontinuation (‘drug holiday’), relative to expression in their drug-naïve counterparts. Bars represent mean values ± SD, n = 3, *p ≤ 0.05. c Expression of TYRP1 at the mRNA level in drug-naïve melanoma cells exposed to vemurafenib for 22 h, relative to its expression in untreated cells. Bars represent mean values ± SD, n = 3. d Expression of TYRP1 at the mRNA level in drug-naïve melanoma cells exposed to trametinib for 22 h, relative to its expression in control cells. Bars represent mean values ± SD, n = 3. e Representative Western blot images showing comparison of TYRP1 and MITF-M protein levels in drug-naïve (–) vs. trametinib-resistant (TRAR) cell lines, also subjected to drug discontinuation (‘drug holiday’; TRAR DH) are included. GAPDH was used as a loading control. f Comparison of expression of TYRP1, SLC45A2, BIRC7 and BCL2A1 in TRAR cell lines either exposed to drug or after drug discontinuation (TRAR DH), relative to expression in their drug-naïve counterparts. Bars represent mean values ± SD, n = 3. Expression of indicated genes in b–d and f was assessed by qRT-PCR and normalized to the expression of a reference gene RPS17