Melanization as unfavorable factor in amelanotic melanoma cell biology

Abstract

The biology of three amelanotic melanoma cell lines (Ab, B16F10, and A375) of different species origin was analyzed during in vitro induced melanization in these cells. Melanin production was induced by DMEM medium characterized by a high level of L-tyrosine (a basic amino acid for melanogenesis). The biodiversity of amelanotic melanoma cells was confirmed by their different responses to melanogenesis induction; Ab hamster melanomas underwent intensive melanization, mouse B16F10 darkened slightly, while human A375 cells did not show any change in melanin content. Highly melanized Ab cells entered a cell death pathway, while slight melanization did not influence cell biology in a significant way. The rapid and high melanization of Ab cells induced apoptosis documented by phosphatidylserine externalization, caspase activation, and mitochondrial energetic state decrease. Melanoma cell type, culture medium, and time of incubation should be taken into consideration during amelanotic melanoma cell culture in vitro. L-tyrosine, as a concentration-dependent factor presented in the culture media, could stimulate some amelanotic melanoma cell lines (Ab, B16F10) to melanin production. The presence of melanin should be considered in the examination of antimelanoma compounds in vitro, because induction of melanin may interfere or be helpful in the treatment of amelanotic melanoma.

Rab3a regulates melanin exocytosis induced by keratinocyte-conditioned medium

“…Notably, comparing with RPMI, DMEM has 3.5 times more L-tyrosine, which is the initial substrate of the key melanogenic enzyme tyrosinase (Yamaguchi and Hearing, 2010;Taisuke and Hearing, 2011;Hirobe, 2014). This enhanced intracellular melanin levels in melanocytes cultured with DMEM was also reported by others (Skoniecka et al, 2021). Furthermore, we detected a 4-fold increase in melanin exocytosis, when compared with melanocytes cultured with RPMI (Figures 1A and 1B).…”

RAB3A Regulates Melanin Exocytosis and Transfer Induced by Keratinocyte-Conditioned Medium

“…Notably, comparing RPMI and DMEM media composition, DMEM contains 3.5 times more L-tyrosine, which is the initial substrate of the key melanogenic enzyme tyrosinase (Yamaguchi and Hearing, 2010;Taisuke and Hearing, 2011;Hirobe, 2014). These enhanced intracellular melanin levels of melanocytes cultured in DMEM were also reported by others (Skoniecka et al, 2021). Interestingly, when melanocytes are cultured in KCM, the levels of exocytosed melanin are 2.5 times higher (Figures 1a and 1c), whereas the amount of intracellular melanin is 50% lower, when compared to melanocytes cultured in DMEM (Figures 1b and 1d).…”

Low-intensity exercise training improves systolic function of heart during metastatic melanoma-induced cachexia in mice

“…Such variations might result from differences in cell culture conditions, mouse strains, or environmental factors. One difference in our study was the use of RPMI 1640 medium for cell culture rather than DMEM, which resulted in less melanin production by the B16F10 cells [ 36 ]. While melanoma melanin content is known to impact radiotherapy efficacy [ 37 ], whether melanization level affects metastasis propensity requires further investigation.…”