LAT is also es sential for amino acid transport in the proximal tubules of the

Pretreatment with GM6001 did not affect the effect of neurotensin on ERK, but markedly reduced neurotensin induced phosphorylation of Akt. These results support INNO-406 887650-05-7 a role of release of EGFR ligand in neurotensin stimulated phosphorylation of EGFR and Akt. However, since neither cetuximab nor GM6001 completely abolished the effect of NT on Akt phosphorylation, it seems likely that additional mechan isms are operating. As expected, the effect of exogenous EGF was insensitive to GM6001. Role of Ca2 in activation of PI3K Akt The results above suggest that neurotensin stimulated phosphorylation of Akt in HCT116 cells is mediated, at pathway to neurotensin. Further experiments showed that the effects of neurotensin and thapsigargin on Akt phosphorylation were sensitive to chelating Ca2 inhibi tors.<br><br> However, we have so far not been able to show that this effect is selective, as EGF stimulated Akt phosphorylation was also attenuated by Ca2 inhibitors. In contrast to the findings in HCT116 cells, thapsigargin did not stimulate phosphorylation of Akt in Panc 1 cells. However, in these cells neurotensin stimulated Akt phosphorylation was abolished by pretreating the cells Lapatinib HER2 阻害剤 with TGX 221, an inhibitor of PI3Kb. This indicates that PI3Kb is involved in neurotensin induced activation of Akt in Panc 1 cells. Signalling pathways involved in neurotensin induced DNA synthesis in HCT116 cells The above results suggest a role for the PLC PKC path way in the DNA synthesis induced by neurotensin in HCT116 cells.<br><br> Furthermore, consistent with a role of ERK in the mitogenic response, pretreatment of the cells with the MEK inhibitor PD98059 strongly reduced both basal and neurotensin induced Lonafarnib 臨床試験 DNA synthesis. Although stimulation with EGF only slightly affected DNA synthesis in the cells, we examined the possibility that activation of the least in part, through transactivation of the EGFR. In search for mechanisms that mediate the release of EGFR ligands in HCT116 cells, we next examined the role of intracellular Ca2. Thapsigargin, which increases the intracellular Ca2 level by inhibiting the SERCA pump, induced phosphorylation of Shc, ERK and Akt. Furthermore, like the effect of neurotensin, the effect of thapsigargin on Shc phosphorylation was abol ished by pretreatment with cetuximab, while the effect on Akt phosphorylation was attenuated, which suggests the involvement of Ca2 in the response of the PI3K EGFR pathway might play a role in neurotensin induced mitogenic stimulation.<br><br> We found that inhibition of the EGFR tyrosine kinase activity by gefitinib or AG1478 resulted in a reduction of both basal and neurotensin induced DNA synthesis. Furthermore, a role for the PI3K pathway in the neurotensin induced mito genesis was likely since the DNA synthesis was reduced by the PI3K inhibitor wortmannin. Discussion In the present study, we have found that neurotensin induced signalling in colon carcinoma cells involves both EGFR dependent and independent pathways. In HCT116 cells, stimulation by neurotensin of ERK phos phorylation and DNA synthesis is mediated by PKC, whereas Akt phosphorylation induced by neurotensin is dependent on EGFR mediated signalling.