Isovitexin Suppresses Stemness of Lung Cancer Stem-Like Cells through Blockage of MnSOD/CaMKII/AMPK Signaling and Glycolysis Inhibition

Retracted: Isovitexin Suppresses Stemness of Lung Cancer Stem-Like Cells through Blockage of MnSOD/CaMKII/AMPK Signaling and Glycolysis Inhibition

[This retracts the article DOI: 10.1155/2021/9972057.].

NCAPG stimulates lung adenocarcinoma cell stemness through aerobic glycolysis

BACKGROUND

Cancer stem cells are pivotal in cancer progression and therapy, including lung adenocarcinoma (LUAD). High NCAPG level is implicated in malignant tumorigenesis, but investigations on NCAPG and LUAD stem cells are warranted. Hence, projecting the impact of NCAPG on cell stemness and the targeted therapy for LUAD is of the essence.

METHODS

Bioinformatics analyzed NCAPG expression in LUAD tissues. qRT-PCR assayed NCAPG expression in LUAD cells. CCK-8 assessed cell viability and cell sphere-forming assay measured sphere-forming ability. Western blot assessed expression of stem cell-related markers (CD133, CD44, Oct-4) and specific genes (HK2, PKM2, LDHA) related to glycolysis metabolism pathway. Cellular glycolytic capacity was assayed by glycolytic metabolites pyruvic acid, lactate, citrate, and malate assay kits, and extracellular acidification rate and oxygen consumption rate analyzers.

RESULTS

NCAPG was upregulated in LUAD and enriched in the aerobic glycolysis pathway, and its expression was positively correlated with that of glycolytic marker genes. Cell function assays revealed that NCAPG stimulated proliferation, stemness, and glycolytic activity of LUAD cells. Rescue experiments unveiled that 2-DG (glycolysis inhibitor) was able to reverse the stimulative impact of NCAPG overexpression on proliferation, stemness, and glycolytic activity of LUAD cells.

CONCLUSION

NCAPG stimulated LUAD cell stemness through activation of glycolysis pathway. NCAPG may be possible biomarker for diagnosis and target for treatment of LUAD.

Regulation of Metabolic Plasticity in Cancer Stem Cells and Implications in Cancer Therapy

Cancer stem cells (CSCs), a subpopulation of tumor cells with self-renewal capacity, have been associated with tumor initiation, progression, and therapy resistance. While the bulk of tumor cells mainly use glycolysis for energy production, CSCs have gained attention for their ability to switch between glycolysis and oxidative phosphorylation, depending on their energy needs and stimuli from their microenvironment. This metabolic plasticity is mediated by signaling pathways that are also implicated in the regulation of CSC properties, such as the Wnt/β-catenin, Notch, and Hippo networks. Two other stemness-associated processes, autophagy and hypoxia, seem to play a role in the metabolic switching of CSCs as well. Importantly, accumulating evidence has linked the metabolic plasticity of CSCs to their increased resistance to treatment. In this review, we summarize the metabolic signatures of CSCs and the pathways that regulate them; we especially highlight research data that demonstrate the metabolic adaptability of these cells and their role in stemness and therapy resistance. As the development of drug resistance is a major challenge for successful cancer treatment, the potential of specific elimination of CSCs through targeting their metabolism is of great interest and it is particularly examined.

FRI-1 Is an Anti-Cancer Isoquinolinequinone That Inhibits the Mitochondrial Bioenergetics and Blocks Metabolic Shifts by Redox Disruption in Breast Cancer Cells

Since breast cancer (BC) cells are dependent on mitochondrial bioenergetics for promoting proliferation, survival, and metastasis, mitochondria highlight as an important target for anticancer drug discovery. FRI-1, methyl 1, 3-dimethyl-5, 8-dioxo-5, 8-dihydro-4-isoquinolinecarboxylate, was previously described as a selective cytotoxic compound on cancer cell lines, however, details on the mechanism of action remain unknown. In this work, we describe that FRI-1 inhibits mitochondrial bioenergetics, producing apoptosis in MCF7 and MDA-MB-231 BC cell lines. FRI-1 decreases the maximal oxygen consumption rate (OCR), Δψm, NADH, and ATP levels, with a notable increase of mitochondrial reactive oxygen species (ROS) production, promoting AMPK activation with pro-survival effects. Moreover, FRI-1 inhibits the metabolic remodeling to glycolysis induced by oligomycin. In isolated tumoral mitochondria, FRI-1 increases Complex I and III-dependent OCR state 2, and this is sensitive to rotenone and antimycin A inhibitor additions, suggesting a redox cycling event. Remarkably, α-ketoglutarate and lipoic acid supplementation reversed and promoted, respectively, the FRI-1-induced apoptosis, suggesting that mitochondrial redox disruption affects 2-oxoglutarate dehydrogenase (OGDH) activity, and this is involved in their anticancer mechanism. Consistent with this, the combination of FRI-1 and CPI-613, a dual inhibitor of redox-sensible tricarboxylic acid (TCA) cycle enzymes PDH and OGDH, produced extensive BC cell death. Taken together, our results suggest that FRI-1 exhibits anticancer effects through inhibition of mitochondrial bioenergetics by redox disruption in BC cells.