TAp73 Modifies Metabolism and Positively Regulates Growth of Cancer Stem–Like Cells in a Redox-Sensitive Manner

Abstract

Purpose: Stem-like cancer cells, with characteristic selfrenewal abilities, remain highly refractory to various clinical interventions. As such, stemness-inhibiting entities, such as tumor suppressor p53, are therapeutically pursued for their anticancer activities. Interestingly, similar implications for tumor suppressor TAp73 in regulating stemness features within stem-like cancer cells remain unknown.Experimental Design: This study utilizes various in vitro molecular biology techniques, including immunoblotting, qRT-PCR, and mass spectrometry-based proteomics, and metabolomics approaches to study the role of TAp73 in human and murine embryonal carcinoma stem-like cells (ECSLC) as well as human breast cancer stem-like cells (BCSLC). These findings were confirmed using patient-derived brain tumor-initiating cells (BTIC) and in vivo xenograft models.Results: TAp73 inhibition decreases the expression of stem cell transcription factors Oct4, Nanog, and Sox-2, as well as tumorsphere formation capacity in ECSLCs. In vivo, TAp73deficient ECSLCs and BCSLCs demonstrate decreased tumorigenic potential when xenografted in mice. Mechanistically, TAp73 modifies the proline regulatory axis through regulation of enzymes GLS, OAT, and PYCR1 involved in the interconversion of proline-glutamine-ornithine. Further, TAp73 deficiency exacerbates glutamine dependency, enhances accumulation of reactive oxygen species through reduced superoxide dismutase 1 (SOD1) expression, and promotes differentiation by arresting cell cycle and elevating autophagy. Most importantly, the knockdown of TAp73 in CD133 HI BTICs, separated from three different glioblastoma patients, strongly decreases the expression of prosurvival factors Sox-2, BMI-1, and SOD1, and profoundly decreases their self-renewal capacity as evidenced through their reduced tumorsphere formation ability.Conclusions: Collectively, we reveal a clinically relevant aspect of cancer cell growth and stemness regulation through TAp73-mediated redox-sensitive metabolic reprogramming.

The lysosomal TRPML1 channel regulates triple negative breast cancer development by promoting mTORC1 and purinergic signaling pathways

“…To assess whether ML1 regulates TNBC growth in vivo [1,3,52–54], we performed an orthotopic xenograft model of breast cancer cells in SCID/NOD mice [55–57]. MDA-MB-231 cells (2 × 10 6 ) expressing ML1 shRNA1 or control shRNA were subcutaneously injected into the mammary fat pads (fat pad number 4) of 8-week-old NOD/SCID mice (51–53).…”

Endothelin-1 as a Mediator of Heme Oxygenase-1-Induced Stemness in Colorectal Cancer: Influence of p53

“…We used the CRC cell lines HCT-116, HCT-116 p53 null, and HT-29 to conduct our in vitro model. These cells have the ability to form tumorospheres within 3-5 days after being seeded in appropriate plates and medium [45][46][47], which allowed us to carry out our study even though the transformation of the parental cells was performed by transient transfection [48,49].…”

Neural Networks Recapitulation by Cancer Cells Promotes Disease Progression: A Novel Role of p73 Isoforms in Cancer-Neuronal Crosstalk

“…The fact that the TAp73α isoform, which is traditionally considered an apoptotic isoform, has a strong effect in co-elevation of stemness and neurotrophic factors might imply a switch of its antioncogenic duties in late tumor stages, in accordance with p73∆Ex2/3 with which it is co-expressed. It would be of great interest to unveil both the underlying mechanism and the contribution of individual p73 isoforms in this process, including certain TAp73 isoforms with persistent overexpression in aggressive stages, for which recent evidence implies a Janus behavior in the context of metastasis-supporting processes [44,45]. An appealing question that warrants further investigation, in view of the complexity of p73 expression patterns in invasive stages, is whether the neurogenic phenotypes of cancer cells reflect a sophisticated combination of the specialized neuronal tasks of each p73 isoform rather than a simplistic dominance of the traditionally oncogenic DNs over the apoptotic TAs.…”