Role of RSK in the cell cycle progression and migration of intestinal tumoral cells induced by PTHrP

CALVO N; CARRIERE P; GENTILI C

Mar del Plata

Congreso; LXI Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC).; 2016

Sociedad Argentina de Investigación Clínica (SAIC)

Parathyroid Hormone-related Peptide (PTHrP) is implicated in several human cancers such as colon carcinoma. This disease is a complex multistep process that involving enhanced cell cycle progression and migration. In previous work we obtained evidence that in the human colorectal adenocarcinoma Caco-2 cells, exogenous PTHrP increases the cell cycle progression via Erk1/2, p38 MAPK and PI3K. Recently we observed that the treatment with the peptide also increases cell migration and the phosphorylation of p90 ribosomal S6 kinase (RSK) (which is an enzyme involved in cell motility) via Erk1/2 in these intestinal cells. However if RSK is implicated in the cell cycle progression and cell migration induced by PTHrP of Caco-2 cells is not known. The objective of this study was to further delineate the molecular mechanisms involved in PTHrP-induced response in these cells.To that end, Caco-2 cells were pre-incubated with an inhibitor of RSK, SL0101, and treated with PTHrP followed by wound-healing, transwell or western blot assays. PTHrP effects on cell migration and on the expression of focal adhesion kinase (FAK), a regulator of cell motility, were prevented by RSK inhibition. In addition, the inhibitor also reversed the up-regulation and the down-regulation induced by PTHrP of cyclin D1 (a positive cell cycle regulator) and p15INK4B and p53 (two negative cell cycle regulators), respectively. Finally, performing subcellular fractionation followed by Western blot analysis we found that the peptide induces the nuclear translocation of RSK, where many of its substrates are located. Taken together, these data suggest that RSK modulates the expression of cell cycle regulators and cell migration in Caco-2 cells treated with PTHrP. In conclusion, the results obtained in this work expand our knowledge on signaling pathways that are involved on Caco-2 cells response to PTHrP.