Cam4 independence mo
Under physiological conditions, intracellular levels of PIP2 and PIP3 phosphoinositols are increased by activation of PIK3 and reduced by the activity of the phosphatase PTEN protein (24).
In this sense, a wider comprehension of the multiple molecular alterations accounting for either response or resistance to treatments with targeted inhibitors may be helpful in assessing, which is the most effective combination of such therapies.
In the present review, we summarize the known molecular mechanisms underlying either intrinsic and acquired drug resistance either alternative roads to melanoma pathogenesis, which may become targets for innovative anticancer approaches.
Melanoma is a heterogeneous disease, with complex pathogenetic mechanisms, as a consequence of specific genetic alterations within several functionally related molecular pathways (1).
In melanocytes, occurrence of BRAF mutations enhances the expression of p16), and subsequent induction of cellular senescence and cell-cycle arrest mechanisms.
This phenomenon appears as a “protective” reaction, in response to an erroneous mitogenic signal (22). Similarly, oncogenic activation of BRAF is able to promote the malignant transformation of melanocytes deficient in p53 (23).
In physiological conditions, the system p16 inhibits protein kinase cyclin-dependent kinase 4 (CDK4)/Cyclin D1 (CCND1), which in turn affects the cell-cycle progression depending on the RB (retinoblastoma susceptibility) protein (12) (Figure 1).