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MITF (microphthalmia-associated transcription factor) is a
lineage-defining transcription factor that regulates melanocyte development,
melanogenesis, pigmentation, differentiation, survival and metabolism. In
melanoma, MITF can function as a lineage-survival oncogene: increased or
amplified MITF supports expression of genes required for proliferation,
melanocytic identity and tumour-cell survival. However, MITF activity is highly
context-dependent. Relatively high MITF can promote differentiation and
proliferation, whereas low MITF states are often associated with dedifferentiation,
invasion, therapy resistance and a more stem-like phenotype. Thus, melanoma cells
can switch between MITF-high proliferative states and MITF-low invasive states.
The cancer-associated direction should therefore be considered
context-dependent rather than universally up or down. MITF
is separate from downstream melanogenesis targets such as TYR,
TYRP1, DCT and melanin production.
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