Mutant p53 blocks SESN1/AMPK/PGC-1α/UCP2 axis increasing mitochondrial O2ˉ· production in cancer cells

Abstract

Background The TP53 tumor suppressor gene is the most frequently altered gene in tumors and mutant p53 gain-of-function isoforms actively promote cancer malignancy. Methods A panel of wild-type and mutant p53 cancer cell lines of different tissues, including pancreas, breast, skin, and lung were used, as well as chronic lymphocytic leukemia (CLL) patients with different TP53 gene status. The effects of mutant p53 were evaluated by confocal microscopy, reactive oxygen species production assay, immunoblotting, and quantitative reverse transcription polymerase chain reaction after cellular transfection. Results We demonstrate that oncogenic mutant p53 isoforms are able to inhibit SESN1 expression and consequently the amount of SESN1/AMPK complex, resulting in the downregulation of the AMPK/PGC-1α/UCP2 axis and mitochondrial O 2 ˉ· production. We also show a correlation between the decrease of reduced thiols with a poorer clinical outcome of CLL patients bearing mutant TP53 gene. The restoration of the mitochondrial uncoupling protein 2 (UCP2) expression, as well as the addition of the radical scavenger N -acetyl- l -cysteine, reversed the oncogenic effects of mutant p53 as cellular hyper-proliferation, antiapoptotic effect, and resistance to drugs. Conclusions The inhibition of the SESN1/AMPK/PGC-1α/UCP2 axis contributes to the pro-oxidant and oncogenic effects of mutant p53, suggesting pro-oxidant drugs as a therapeutic approach for cancer patients bearing mutant TP53 gene.

Mutant p53-Associated Molecular Mechanisms of ROS Regulation in Cancer Cells

“…In this regard, it has been demonstrated that mutant forms of p53 can inhibit PGC-1α function [137]. Furthermore, we showed that the inhibition of PGC-1α by mutant p53 is linked to the downregulation of mitochondrial UCP2 expression, favoring a determining ROS increase [8].…”

“…Many years of research unveiled that GOF p53 mutations support tumor progression by regulating a complex overview of diversified pathways associated with: adaptive metabolic switch in responses to cancer-related stressing conditions; reduced response to chemotherapy; promotion of migration, invasion, and metastasis [6,7]. Cancer cells expressing mutant p53 show high levels of ROS compared with wild type p53 cells and we and others discovered that GOF mutant p53 isoforms, among the other abilities, contribute to enhance ROS levels in cancer cells through a coordinated regulation of several redox-related enzymes and signaling pathways, thus favoring cancer cell growth [8].…”

“…However, the precise molecular mechanisms involved in this abnormal regulation of ROS by mutant p53 isoforms were still incomplete. In our previous studies, we reported that mutant p53 proteins (p53-R175H, p53-R248H, and p53-R273H) were able to repress the transcription of SESN1 and SESN2, and consequently the amount of the SESN/AMPK complex, resulting in the inhibition of AMPK signaling in pancreatic and breast cancer cells [8,89]. Notably, SESN/AMPK blockage has been shown functionally involved in the pro-oxidant role of mutant p53 in cancer cells through stimulation of mitochondrial O 2 − • production without damaging mitochondrial DNA (mtDNA) [8].…”

“…In our previous studies, we reported that mutant p53 proteins (p53-R175H, p53-R248H, and p53-R273H) were able to repress the transcription of SESN1 and SESN2, and consequently the amount of the SESN/AMPK complex, resulting in the inhibition of AMPK signaling in pancreatic and breast cancer cells [8,89]. Notably, SESN/AMPK blockage has been shown functionally involved in the pro-oxidant role of mutant p53 in cancer cells through stimulation of mitochondrial O 2 − • production without damaging mitochondrial DNA (mtDNA) [8]. Moreover, through dysregulation of SESN/AMPK, axis mutant p53 proteins have been shown to promote autophagy defects in cancer cells [89], which may lead in turn to accumulation of abnormal mitochondria and consequently ROS induction, genomic instability, and cancer initiation and progression [2].…”

“…These studies support the existence of different mechanisms induced by mutant p53 proteins to modulate the expression of secreted inflammatory cytokines in order to sustain an inflammatory tumor microenvironment, thus potentially contributing to promote oxidative stress and increased cancer aggressiveness. [110,117,118,120,121] R175H, R248W, R273H NF-kB Lung, pancreatic, breast and colon cancer [158][159][160][161][162] R175H, R281G, R273H Cytokines Lung, breast, pancreatic and colon cancer [157,164,165] R175H, R273H PGC1-α Lung, colon and pancreatic cancer [8,137] R175H, R280K, R273H NRF2 Colon carcinoma, oesophageal adenocarcinoma, lung and breast cancer [133][134][135] R175H, R273H AMPK Pancreatic and breast cancer [8,89,110] R175H, R248H, R273H SESNs Breast and pancreatic cancer [8,89] R175H, R273H UCP2 Lung, pancreatic and breast cancer [8] R175H, R273H GSH Oesophageal adenocarcinoma, pancreatic and breast cancer [128,135] R175H, R273H Autophagy Lung carcinoma, pancreatic and breast cancer [89]…”