Involvement of ER stress and MAPK pathways in the apoptotic effect induced by a triazolyl peptidyl penicillin in murine melanoma cells

PATRICIA G. CORNIER; ERNESTO G. MATA; CARINA M. DELPICCOLO; VIVIANA C. BLANK; YANINA BELLIZZI; DORA B. BOGGIAN; LEONOR P. ROGUIN

Congreso; Reunión anual SAIC SAI SAFIS; 2018

The triazolyl peptidyl penicillins (TAPs) are novel hybrids compounds having in their structure a penicillanic core linked to a peptide portion via a triazole group. In a previous study, we showed that the derivative containing the dipeptide Leu-Phe (TAP7f) behaves as a selective and potent antitumor agent that induces an apoptotic response. In order to further investigate the mechanism of action of this compound, we first examined the possible contribution of the ER stress to the cell death process. The significant increase in the expression levels of the ER chaperones Calnexin, Bip, ATF4 and CHOP (~2 fold) observed after 3-6 h of incubation with TAP7f suggested the activation of an unfolded protein response. We then evaluated the effect of TAP7f on the modulation of signaling pathways involved in cell proliferation. By Western blot analysis, we found a significant increase in the phosphorylation levels of p38MAPK, JNK and AKT after 15-30 min of incubation with 20 µM of TAP7f. We also demonstrated a decrease of ERK 1/2 phosphorylation after 30-45 min. To study the participation of these pathways in the antitumor effect of TAP7f, cell viability was determined after pre-incubating cells with specific pharmacological inhibitors (Inh). Results showed that cell viability increased from 36±3% to 51±4% or 55±7% after pre-treatment with SP600125 (JNK Inh) and SB203580 (p38 Inh), respectively. When cells were pre-incubated with PD98059 (Erk 1/2 Inh) or wortmannin (PI3K Inh), cell proliferation diminished from 36±3% to 21±7% or 9±2%, respectively. Taken together, our results suggested the contribution of ER stress, JNK and p38 MAPK pathways to the apoptotic cell death induced by TAP7f, whereas Erk 1/2 and PI3K cascades would be related to survival responses. The knowledge of the role played by the intracellular signals regulating cell death could certainly contribute to find new intracellular targets for melanoma treatment.