The PI3K AKT pathway, the PLC? 1 pathway as well as the MAPK cascades are downstream targets of the CaSR. In our study, calcium treatment 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 impact around the MAP kinases p38 and JNK. The focal adhesion adapter protein paxillin too as c Jun, each downstream targets of JNK, showed comparable activity patterns. Inhi biting CaSR with NPS 2143 these enhancements have been pre vented and the phosphorylation with the signal mediator with all the highest calcium sensitivity, AKT, was decreased. The further reduction of AKT activity just after inhibition of CaSR indicates a basement activity of CaSR even without adding calcium.
The culture medium consists of a low amount of calcium not specified by the business. Presumably this low calcium concentration results in a slightly activation of CaSR and consequently also of AKT phosphorylation. This effect appears to become inhibited you can look here by NPS 2143. The lowered AKT activity induced by NPS 2143 therapy confirms the duty 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 strategies, which are described as downstream targets of CaSR, getting the crucial pathways in the CaSR signaling in RCC cells promoting bone certain metastasis. On the other hand, ERK as a downstream target of CaSR is discussed controversially and a few studies hypothesize the ERK pathway being in volved in extracellular calcium induced cell migration, once more confirming a cell form certain function of CaSR as already described.
The primary regulator of your AKT pathway is the tumor selleck suppressor PTEN. As an antagonist in the PI3Kinase, PTEN inhibits the activa tion of AKT and thereby down regulates cell prolifera tion and migration. Moreover, in our former investigations we established a correlation among low PTEN expression in specimens of RCC patients and poor prognosis triggered by metastasis. In bone me tastasizing RCC cells, PTEN expression was approxi mately 50% decrease than in non metastasizing cells. The expression of PTEN correlated inversely together with the activ ity of AKT. In addition, the expression of PTEN was very calcium sensitive. Calcium therapy resulted in an just about total decline inside the expression of PTEN. This implicates that the per se low PTEN expression in bone metastasizing RCC cells is additional lowered by the bone microenvironment, consequently activating the AKT signaling pathway and advertising bone metastasis. Our study indicates that bone metastasis of RCC is promoted by an enhanced expression of CaSR.