PDE5 inhibitors enhance the lethality of pemetrexed through inhibition of multiple chaperone proteins and via the actions of cyclic GMP and nitric oxide.

ABSTRACT: Phosphodiesterase 5 (PDE5) inhibitors prevent the breakdown of cGMP that results in prolonged protein kinase G activation and the generation of nitric oxide. PDE5 inhibitors enhanced the anti-NSCLC cell effects of the NSCLC therapeutic pemetrexed. [Pemetrexed + sildenafil] activated an eIF2α - ATF4 - CHOP - Beclin1 pathway causing formation of toxic autophagosomes; activated a protective IRE1 - XBP-1 - chaperone induction pathway; and activated a toxic eIF2α - CHOP - DR4 / DR5 / CD95 induction pathway. [Pemetrexed + sildenafil] reduced the expression of c-FLIP-s, MCL-1 and BCL-XL that was blocked in a cell-type -dependent fashion by either over-expression of HSP90 / GRP78 / HSP70 / HSP27 or by blockade of eIF2α-CHOP signaling. Knock down of PKGI/II abolished the ability of sildenafil to en

SUBMITTER: Booth L 

PROVIDER: S-EPMC5352068 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature