Phosphoinositide specific phospholipase C?1 inhibition-driven autophagy caused cell death in human lung adenocarcinoma A549 cells in vivo and in vitro.

ABSTRACT: Our previous studies indicated that phosphoinositide specific phospholipase C?1 (PLC?1) was involved in autophagy induction in colon and hepatic carcinoma cells. However, whether and how PLC?1 regulation in human lung adenocarcinoma is linked to autophagy remains unclear. Here, we assessed the protein expression of PLC?1 in human lung adenocarcinoma tissue using immunohistochemistry assay and the relationship between PLCG1 and autophagy in The Cancer Genome Atlas Network (TCGA) using Spearman correlation analysis and GSEA software. Furthermore, the interaction between PLC?1 and autophagy-related signal molecules was investigated in human lung adenocarcinoma A549 cells treated with different inhibitors or transduction with lentivirus-mediated PLC?1 gene short-hairpin RNA (shRNA) vectors using MTT, clonogenicity, Transwell migration, RT-PCR, Caspase-3, mitochondrial transmembrane potential, and western blotting assays, as well as transmission electron microscope technique. Additionally, the effect of shRNA/PLC?1 alone or combined with autophagic activator Lithium Chloride (LiCl) on tumor growth and metastasis was measured using immunohistochemistry and assays in A549 xenograft nude mouse model. The results showed that increased PLC?1 expression occurred frequently in human lung adenocarcinoma tissue with higher grades of T in TNM staging classification. PLC?1 significantly enriched in autophagic process and regulation, which negatively regulating autophagy was enriched in higher expression of PLC?1. PLC?1 inhibition partially reduced cell proliferation and migration of A549 cells, with an increased autophagic flux involving alterations of AMPK?, mTOR, and ERK levels. However, PLC?1 inhibition-driven autophagy led to cell death without depending on Caspase-3 and RIP1. Additionally, the abrogation of PLC?1 signaling by shRNA and combination with autophagic activator LiCl could efficaciously suppress tumor growth and metastasis in A549 xenograft nude mice, in combination with a decrease in P62 level. These findings collectively suggest that reduction of cell proliferation and migration by PLC?1 inhibition could be partially attributed to PLC?1 inhibition-driven autophagic cell death (ACD). It highlights the potential role of a combination between targeting PLC?1 and autophagy pathway in anti-tumor therapy, which may be an efficacious new strategy to overcome the autophagy addition of tumor and acquired resistance to current therapy.

SUBMITTER: Lu X 

PROVIDER: S-EPMC7085223 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature