Update on the effects of the sodium pump α1 subunit on human glioblastoma: from the laboratory to the clinic

Downregulation of ATP1A1 Expression by Panax notoginseng (Burk.) F.H. Chen Saponins: A Potential Mechanism of Antitumor Effects in HepG2 Cells and In Vivo

The Na⁺/K⁺-ATPase α1 subunit (ATP1A1) is a potential target for hepatic carcinoma (HCC) treatment, which plays a key role in Na⁺/K⁺ exchange, metabolism, signal transduction, etc. In vivo, we found that Panax notoginseng saponins (PNS) could inhibit tumor growth and significantly downregulate the expression and phosphorylation of ATP1A1/AKT/ERK in tumor-bearing mice. Our study aims to explore the potential effects of PNS on the regulation of ATP1A1 and the possible mechanisms of antitumor activity. The effects of PNS on HepG2 cell viability, migration, and apoptosis were examined in vitro. Fluorescence, Western blot, and RT-PCR analyses were used to examine the protein and gene expression. Further analysis was assessed with a Na⁺/K⁺-ATPase inhibitor (digitonin) and sorafenib in vitro. We found that the ATP1A1 expression was markedly higher in HepG2 cells than in L02 cells and PNS exhibited a dose-dependent effect on the expression of ATP1A and the regulation of AKT/ERK signaling pathways. Digitonin did not affect the expression of ATP1A1 but attenuated the effects of PNS on the regulation of ATP1A1/AKT/ERK signaling pathways and enhanced the antitumor effect of PNS by promoting nuclear fragmentation. Taken together, PNS inhibited the proliferation of HepG2 cells via downregulation of ATP1A1 and signal transduction. Our findings will aid a data basis for the clinical use of PNS.

Exploring the Therapeutic Potential of Membrane Transport Proteins: Focus on Cancer and Chemoresistance

Improving the therapeutic efficacy of conventional anticancer drugs represents the best hope for cancer treatment. However, the shortage of druggable targets and the increasing development of anticancer drug resistance remain significant problems. Recently, membrane transport proteins have emerged as novel therapeutic targets for cancer treatment. These proteins are essential for a plethora of cell functions ranging from cell homeostasis to clinical drug toxicity. Furthermore, their association with carcinogenesis and chemoresistance has opened new vistas for pharmacology-based cancer research. This review provides a comprehensive update of our current knowledge on the functional expression profile of membrane transport proteins in cancer and chemoresistant tumours that may form the basis for new cancer treatment strategies.

ATP1A1 Integrates AKT and ERK Signaling via Potential Interaction With Src to Promote Growth and Survival in Glioma Stem Cells

Glioma stem cells (GSCs) have been considered to be responsible for treatment failure due to their self-renewal and limitless proliferative property. Recently, the Na⁺/K⁺-ATPase a1 (ATP1A1) subunit was described as a novel therapeutic target for gliomas. Interestingly, our previous proteomics study revealed that ATP1A1 is remarkably overexpressed in GSCs. In the current study, we investigated the role of ATP1A1 in regulating growth, survival, and tumorigenicity of primary human GSCs and the underlying molecular mechanism. We tested RNA and protein expression of ATP1A1 in glioma tissues and GSCs. In addition, we knocked down ATP1A1 in GSCs and assessed the effects thereof on growth, survival, and apoptosis. The role of ATP1A1 in signaling pathways was investigated in vitro. We found that the ATP1A1 expression level was associated with the grade of glioma. Knockdown of ATP1A1 in GSCs in vitro inhibited cell proliferation and survival, increased apoptosis, and halted cell-cycle progression at the G1 phase. Cell proliferation and survival were resumed upon rescue of ATP1A1 expression in ATP1A1-knockdown GSCs. The ERK1/2 and AKT pathways were inhibited through suppression of Src phosphorylation by ATP1A1 knockdown. Collectively, our findings suggest that ATP1A1 overexpression promotes GSC growth and proliferation by affecting Src phosphorylation to activate the ERK1/2 and AKT signaling pathways.