AN ALTERNATIVE SPLICE VARIANT OF MKP-2 TRANSCRIPT IS EXPRESSED IN A NON-SMALL-CELL LUNG CANCER CELL LINE

SILVANA IRIS NUDLER, MARÍA MERCEDES MORI SEQUEIROS, JUAN MANUEL COHEN SABBAN, CRISTINA PAZ

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Sociedades de Biociencias

AN ALTERNATIVE SPLICE VARIANT OF MKP-2 TRANSCRIPT IS EXPRESSED IN A NON-SMALL-CELL LUNG CANCER CELL LINESilvana Iris Nudler, María Mercedes Mori Sequeiros, Juan Manuel Cohen Sabban, Cristina Paz.INBIOMED (UBA-CONICET).MAP kinases (MAPK) ERKs, JNKs and p38 are activated by dual phosphorylation and regulate several processes such as proliferation, differentiation and apoptosis. Given that MAPK phosphatase (MKP) family members inactivate MAPK, they are potential modulators of MAPK-dependent processes. MKP-2 (or DUSP4) is a nuclear dual activity phosphatase able to dephosphorylate JNK1/2 and ERK1/2 and induced by stress conditions. An alternative splice variant of MKP-2 transcript and protein were found in PC3 prostate and MDA-MB-231 breast cancer cells and human prostate biopsies. This variant, generated by exon skipping and referred to as the S or short variant, displays phosphatase activity but lacks several motives involved in the subcellular localization and regulation. Thus, the L (complete) and S variants could have different biological roles, even though the characterization of the S transcript has not been fully elucidated yet. We analyzed transcript expression in nonsmall-cell lung cancer cell line A549. RT-PCR analysis showed a time-dependent increase in L and S transcripts after cell stimulation with 0.1 μg/mL LPS (bacterial lipopolysaccharides), a stimulus able to induce MKP-2 L. The L transcript rendered a three-fold increase vs. control after 1 h (P<0.01) and reached 8-fold increase after 4 h (P<0.001). LPS also increased mRNA- MKP-2 S levels after 2 h (P<0.05). Our study also showed that the predominant transcript is the L variant. Transcription inhibitor Actinomicyn D and PD98059, which impair ERK activation, both blocked the effect of LPS on L and S transcripts. In sum, we report for the first time the expressionof the alternative splice variant of MKP-2 in the A549 cell line. As S isoform lacks important sites involved in its regulation, such as a nuclear localization sequence, a different L/S ratio could differentially modulate MAPK-dependent events. Also, we show that L and S transcripts are induced by LPS at transcriptional level by anERK-dependent mechanism.Keywords: DUSP4; MKP-2; splice variant; lung cancer cell line.