The PI3K AKT pathway, the PLC? 1 pathway and also the MAPK cascades are downstream targets of the CaSR. In our study, calcium therapy resulted in a clearly enhanced activity of AKT PKB and PLC? 1 in bone metastasizing cells but not in non metastasizing cells. Moreover, in bone me tastasizing cells, calcium had an activating effect around the MAP kinases p38 and JNK. The focal adhesion adapter protein paxillin at the same time as c Jun, each downstream targets of JNK, showed comparable activity patterns. Inhi biting CaSR with NPS 2143 these enhancements were pre vented along with the phosphorylation on the signal mediator using the highest calcium sensitivity, AKT, was decreased. The added reduction of AKT activity right after inhibition of CaSR indicates a basement activity of CaSR even without having adding calcium.
The culture medium contains a low level of calcium not specified by the corporation. Presumably this low calcium concentration results in a slightly activation of CaSR and consequently also of AKT phosphorylation. This effect appears to be inhibited selleck chemical by NPS 2143. The decreased AKT activity induced by NPS 2143 treatment confirms the responsibility of CaSR for the calcium dependent effects. In contrast, calcium had no activating impact on ERK. This suggests AKT, PLC? 1, p38 and JNK paxillin signaling path techniques, which are described as downstream targets of CaSR, being the critical pathways within the CaSR signaling in RCC cells promoting bone distinct metastasis. Having said that, ERK as a downstream target of CaSR is discussed controversially and some research hypothesize the ERK pathway being in volved in extracellular calcium induced cell migration, once more confirming a cell sort precise function of CaSR as currently described.
The main regulator on the AKT pathway will be the tumor selleck chemicals suppressor PTEN. As an antagonist with the PI3Kinase, PTEN inhibits the activa tion of AKT and thereby down regulates cell prolifera tion and migration. In addition, in our former investigations we established a correlation amongst low PTEN expression in specimens of RCC sufferers and poor prognosis caused by metastasis. In bone me tastasizing RCC cells, PTEN expression was approxi mately 50% reduce than in non metastasizing cells. The expression of PTEN correlated inversely with the activ ity of AKT. Moreover, the expression of PTEN was very calcium sensitive. Calcium remedy resulted in an just about comprehensive decline within the expression of PTEN. This implicates that the per se low PTEN expression in bone metastasizing RCC cells is further decreased by the bone microenvironment, consequently activating the AKT signaling pathway and promoting bone metastasis. Our study indicates that bone metastasis of RCC is promoted by an enhanced expression of CaSR.