Therefore, the inhibition of MEK1/2 with specific MEK inhibitors may result in blocking MAPK signaling from multiple upstream oncogenes. selleck Trichostatin A Preclinical studies suggest that some NRAS mutant cutaneous melanomas may also exhibit sensitivity to RAF or MEK inhibition, whereas KRAS mutations have conferred only marginal sensitivity. Gene expression profiling studies mapping the gene signatures downstream of a constitutively activated MAPK pathway suggested that cutaneous melanoma cell lines with NRAS mutations are less dependent in signaling through this pathway compared to BRAFV600E mutant cu taneous melanoma cell lines, explaining in part the differential sensitivity of NRAS and BRAF mutant cells to MEK inhibitors.

BRAF and NRAS mutations are absent in melanomas arising in the uveal layer of the eye, but mutually exclusive somatic mutations in the heterotrimeric G protein alpha subunit, GNAQ, or in GNA11, are present in the great majority of uveal melanomas. Inhibitors,Modulators,Libraries It had long been noted that uveal melanomas have constitutive MAPK signaling, and it is now understood that it is because of the presence of GNAQ or GNA11 mutations. These muta tions occur in codons 183 or 209 in the Ras like domain and result in constitutive Inhibitors,Modulators,Libraries activation, turning the GNA pro teins into dominant acting oncogenes signaling through the MAPK pathway. GNAQ knockdown, as well as treatment with the U0126 MEK inhibitor, resulted in inhib ition of MAPK signaling and loss of viability. Therefore, MEK inhibition may be a way to treat metastatic melanoma of uveal origin, a disease that has been highly refractory to most therapies tested to date.

TAK733 represents a novel and distinct inhibitor of MEK that is capable of Inhibitors,Modulators,Libraries allosteric inhibition of the RAF substrates MEK 1 and MEK 2. This compound has been characterized extensively and shown to possess desirable drug like attributes. In the current studies we have analyzed the sensitivity and resistance of human Inhibitors,Modulators,Libraries cutaneous and uveal melanoma cell lines to this novel MEK inhibitor, with analysis of the oncogenic driver mutations and downstream signaling alterations and functional effects. Results Sensitivity of cutaneous and uveal melanoma cell lines to TAK733 Cutaneous and uveal melanoma cell lines were cultured in vitro in the presence of increasing concentrations of TAK 733 for 72 hours to determine the half maximal inhibitory concentration in cell proliferation assays.

Cell lines with an IC50 less than 10 nM were considered sensitive, and cell lines with IC50 less than 1 nM were considered highly sensitive. Among 12 BRAFV600E mutated cutaneous cell lines tested, seven were Inhibitors,Modulators,Libraries Calcitriol clinical highly sensitive to TAK 733 with IC50s less than 1 nM. Five BRAFV600E mutant cutaneous cell lines had an IC50 higher than 100 nM and were considered highly resistant to this agent.