Autophagy Regulated by Gain of Function Mutant p53 Enhances Proteasomal Inhibitor-Mediated Cell Death through Induction of ROS and ERK in Lung Cancer Cells

Abstract

Mutations in p53, especially gain of function (GOF) mutations, are highly frequent in lung cancers and are known to facilitate tumor aggressiveness. Yet, the links between mutant GOF-p53 and lung cancers are not well established. In the present study, we set to examine how we can better sensitize resistant GOF-p53 lung cancer cells through modulation of cellular protein degradation machineries, proteasome and autophagy. H1299 p53 null lung cancer cells were stably transfected with R273H mutant GOF-p53 or wild-type (wt) p53 or empty vectors. The presence of R273H-P53 conferred the cancer cells with drug resistance not only against the widely used chemotherapeutic agents like cisplatin (CDDP) or 5-flurouracil (5-FU) but also against potent alternative modes of therapy like proteasomal inhibition. Therefore, there is an urgent need for new strategies that can overcome GOF-p53 induced drug resistance and prolong patient survival following failure of standard therapies. We observed that the proteasomal inhibitor, peptide aldehyde N-acetyl-leu-leu-norleucinal (commonly termed as ALLN), caused an activation of cellular homeostatic machinery, autophagy in R273H-P53 cells. Interestingly, inhibition of autophagy by chloroquine (CQ) alone or in combination with ALLN failed to induce enhanced cell death in the R273H-P53 cells; however, in contrast, an activation of autophagy by serum starvation or rapamycin increased sensitivity of cells to ALLN-induced cytotoxicity. An activated autophagy was associated with increased ROS and ERK signaling and an inhibition of either ROS or ERK signaling resulted in reduced cytotoxicity. Furthermore, inhibition of GOF-p53 was found to enhance autophagy resulting in increased cell death. Our findings provide novel insights pertaining to mechanisms by which a GOF-p53 harboring lung cancer cell is better sensitized, which can lead to the development of advanced therapy against resistant lung cancer cells.

Chiaurinib Selectively Inhibits Colorectal Cancer with KRAS Wild-Type by Modulation of ROS through Activating the p53 Signaling Pathway

“…Previous studies have proven that activation of the p53 signaling pathway led to imbalance of oxidative phosphorylation, thus inducing ROS production 20 Supplementary Fig. 3).…”

p53 siRNA promotes autophagy of U2OS cells through its target gene Rap2B

“…Our previous study has elucidated that the mTOR-independent pathway regulated autophagy in which the direct activation of EPAC/Rap2B by cAMP activates PLCε to upregulate the levels of IP3 and induce the release of Ca 2+ from the endoplasmic reticulum (Di et al, 2017). In recent, the roles of p53 in the regulation of autophagy have been reported (Sui et al, 2011;Saini et al, 2019). Rap2B is the target gene of p53, and Rap2B can activate PLCε and promote the release of downstream IP3 and Ca 2+ .…”

<p>Functional Autophagic Flux Regulates AgNP Uptake And The Internalized Nanoparticles Determine Tumor Cell Fate By Temporally Regulating Flux</p>

“…Immunoblotting was performed following methods described previously 15. The blots were probed with specific primary antibodies (dilution 1:1000).…”