Protein kinase C b1(PKCb1) inhibits the malignant phenotype of the human pancreatic tumor-derived cell line PANC1

STÉFANO M. CIRIGLIANO; LAURA V. MAURO; VALERIA C. GROSSONI; ELISA D. BAL DE KIER JOFFÉ; LUCAS L. COLOMBO; LYDIA I. PURICELLI; ALEJANDRO J. URTREGER

Chicago

Congreso; 103rd Annual Meeting of the American Associaton for Cancer Research; 2012

American Associaton for Cancer Research (AACR)

Pancreatic cancer is a deadly disease with a 5% overall survival after five years. Different members of the PKC family have been described as modulators of pancreatic cancer progression but, till nowadays, the relevance of each PKC isoform in this process is unclear. The aim of the present work was to study the effect of PKCb1 overexpression, on several critical determinants of tumor progression using the human pancreatic tumor-derived cell line PANC1. Cells were stably transfected with an expression vector containing the full-length PKCb1 gene (PKCb1-PANC1) or with the empty vector, as control (pMTH-PANC1). While no morphologic alterations could be detected in vitro, PKCb1 overexpression induced a significant reduction in the proliferative capacity of PANC1 cells. The reduction in this capacity could be associated with a decrease in Cyclin D1, Cyclin E and phosphorylated ERK1/2 levels, and an increase in p21 expression levels, as measured by Western blot. In addition PKCb1-PANC1 cells showed an increased resistance to cell death induced by serum starvation (% viability: 58.54±4.1 vs 39.29±4.2 in pMTH-PANC1). Using flow cytometry we could determine that serum deprivation promoted PKCb1-PANC1 arrest in the G1 phase of the cell cycle (cells in G0/G1: 86.7±1.0% vs 45.5±0.8% in pMTH-PANC1). Moreover, the overexpression of PKCb1 reduced the in vitro invasive capacity using Matrigel coated transwells (cells x 10 microscopic x400 fields: 2.22±0.9 vs 10.10±2.6 in pMTH-PANC1, p 0.05). This behavior could be associated with a significant inhibition of secreted proteases activity (uPA: 4.11±0.8 vs 12.32±4.1 IU/mg/24h in pMTH-PANC1, and MMP-9: 15.24±0.03 vs 24.89±2.6 AU/mg in pMTH-PANC1). When control and PANC1-PKCb1 cells were s.c. inoculated into nude mice it was observed that PKCb1 cells were almost unable to grow and form tumors while vector-transfected cells retained this ability. In sum, our results suggest that PKCb1 overexpression in human pancreatic tumor cells PANC1 induced a less malignant phenotype both in vivo and in vitro.