Modifications in the ranges of pERK protein have been established by immunocytochemical evaluation in these HCC tumor cells. Sorafenib inhibited ERK phospho rylation in a dose dependent manner among 5 and 20m. However, additional analyses exposed the degree of inhibition in these HCC cell lines was considerably vary ent in line with their basal pERK expression levels. We identified the sorafenib pERK inhibition effect in SMMC 7721 cells, with reduced pERK levels, was drastically weaker than the other 3 HCC cell lines with relatively higher basal pERK levels. Within the contrary, no significant modify in pERK phosphorylation was observed following 5 FU remedy. It truly is doable that the antitumor action of sorafenib could be on account of its skill to inhibit angiogenesis related tyro sine kinases as well as other RAF MEK ERK independent mechanisms.
By way of example, Raf one continues to be proposed to induce the phosphorylation of proteins that manage apop tosis independently of MEK and ERK. Also, the outcomes of clinical trial analyses of sorafenib in renal full article cell carcinoma and melanoma haven’t supplied suffi cient info to conclude that the clinical value is related with inhibition of the RAF MEK ERK signaling pathway. However, good benefits were observed in this research. In cell viability assays, sorafenib inhibited proliferation of all HCC cell lines with various basal pERK levels in a dose dependent method.
Furthermore, the results of sorafenib inhibitor pf562271 have been considerably correlated with basal pERK levels in these HCC cell lines by correlation evaluation among the IC50 values of sorafenib and their pERK density values, indicating that sorafenib sensitivity could have direct links using the activation on the RAF MEK ERK signaling path way and basal pERK levels in HCC tumor cells. To much more directly determine the connection involving pERK expression and sensitivity to sorafenib, we made use of U0126, a selective inhibitor of MEK one two, to inhibit the MEK ERK pathway and lessen basal pERK expression in MHCC97 H cells without the need of influencing cell proliferation. We then assessed cellular responsiveness to sorafenib following pERK down regulation. The observations showed the pre treated cells expressed a lot lower ranges of pERK and became appreciably much less delicate to sorafenib mediated development inhibition.
These observations are flawlessly con sistent with our hypothesis that the RAF MEK ERK signal ing pathway is crucial for sorafenib mediated growth inhibition and that sensitivity to sorafenib is right linked to the activation of this pathway and basal pERK expression. These final results also confirm the findings of Ghassan K Abou Alfas group within a phase II clinical trial on treating state-of-the-art HCC individuals with sorafenib that observed that patients with tumors containing higher levels of pERK had been far more delicate, or responsive, to sorafenib, supporting the notion that pERK may possibly be a valuable biomar ker in treating HCC with sorafenib.