NR1H4-mediated circRHOBTB3 modulates the proliferation, metastasis, and Warburg effects of cervical cancer through interacting with IGF2BP3

Globally, cervical cancer (CC) ranks as the fourth most common cancer and the most lethal malignancy among females of reproductive age. The incidence of CC is increasing in low-income countries, with unsatisfactory outcomes and long-term survival for CC patients. Circular RNAs (CircRNAs) are promising therapeutics that target multiple cancers. In this study, we investigated the tumorigenic role of circRHOBTB3 in CC, showing that circRHOBTB3 is highly expressed in CC cells and circRHOBTB3 knockdown also repressed CC proliferation, migration, invasion, and the Warburg effects. CircRHOBTB3 interacted with the RNA-binding protein, IGF2BP3, to stabilize its expression in CC cells and is putatively transcriptionally regulated by NR1H4. In conclusion, this novel NR1H4/circRHOBTB3/IGF2BP3 axis may provide new insights into CC pathogenesis.

Coenzyme Q0 defeats NLRP3-mediated inflammation, EMT/metastasis, and Warburg effects by inhibiting HIF-1α expression in human triple-negative breast cancer cells

Coenzyme Q₀ (CoQ₀) is a derivative quinone from Antrodia camphorata (AC) that exerts anticancer activities. This study examined the anticancer attributes of CoQ₀ (0-4 µM) on inhibited anti-EMT/metastasis and NLRP3 inflammasome, and altered Warburg effects via HIF-1α inhibition in triple-negative breast cancer (MDA-MB-231 and 468) cells. MTT assay, cell migration/invasion assays, Western blotting, immunofluorescence, metabolic reprogramming, and LC-ESI-MS were carried out to assess the therapy potential of CoQ₀. CoQ₀ inhibited HIF-1α expression and suppressed the NLRP3 inflammasome and ASC/caspase-1 expression, followed by downregulation of IL-1β and IL-18 expression in MDA-MB-231 and 468 cells. CoQ₀ ameliorated cancer stem-like markers by decreasing CD44 and increasing CD24 expression. Notably, CoQ₀ modulated EMT by upregulating the epithelial marker E-cadherin and downregulating the mesenchymal marker N-cadherin. CoQ₀ inhibited glucose uptake and lactate accumulation. CoQ₀ also inhibited HIF-1α downstream genes involved in glycolysis, such as HK-2, LDH-A, PDK-1, and PKM-2 enzymes. CoQ₀ decreased extracellular acidification rate (ECAR), glycolysis, glycolytic capacity, and glycolytic reserve in MDA-MB-231 and 468 cells under normoxic and hypoxic (CoCl₂) conditions. CoQ₀ inhibited the glycolytic intermediates lactate, FBP, and 2/3-PG, and PEP levels. CoQ₀ increased oxygen consumption rate (OCR), basal respiration, ATP production, maximal respiration, and spare capacity under normoxic and hypoxic (CoCl₂) conditions. CoQ₀ increased TCA cycle metabolites, such as citrate, isocitrate, and succinate. CoQ0 inhibited aerobic glycolysis and enhanced mitochondrial oxidative phosphorylation in TNBC cells. Under hypoxic conditions, CoQ₀ also mitigated HIF-1α, GLUT1, glycolytic-related (HK-2, LDH-A, and PFK-1), and metastasis-related (E-cadherin, N-cadherin, and MMP-9) protein or mRNA expression in MDA-MB-231 and/or 468 cells. Under LPS/ATP stimulation, CoQ₀ inhibited NLRP3 inflammasome/procaspase-1/IL-18 activation and NFκB/iNOS expression. CoQ₀ also hindered LPS/ATP-stimulated tumor migration and downregulated LPS/ATP-stimulated N-cadherin and MMP-2/-9 expression. The present study revealed that suppression of HIF-1α expression caused by CoQ₀ may contribute to inhibition of NLRP3-mediated inflammation, EMT/metastasis, and Warburg effects of triple-negative breast cancers.

NDUFA4L2 promotes trastuzumab resistance in HER2-positive breast cancer

Background:

Trastuzumab (Herceptin) is the key systemic therapy for HER2-positive breast cancer. However, the initial response rate is limited to approximately 50% in patients. Moreover, most patients, especially at an advanced stage, eventually develop acquired resistance. Understanding the mechanisms of trastuzumab resistance is crucial for achieving better treatment outcome in this group of patients.

Methods:

A trastuzumab-resistant (TR) cell line was developed using the BT474 HER2-positive breast cancer cell line. Whole-transcriptome expression array was performed and the TR-related gene NDUFA4L2 was identified by differential expression analysis between BT474 and BT474-TR. Mitochondrial localization of NDUFA4L2 was confirmed by immunofluorescence and western blotting using mitochondrial fractionation. Mitochondrial function and energy metabolism were evaluated using Seahorse, ATP production, and lactate production assays, and cellular reactive oxygen species (ROS) levels were determined using DCFDA. NDUFA4L2 expression in patients was evaluated by immunohistochemistry, and relapse-free survival was analyzed using the Kaplan–Meier method.

Results:

NDUFA4L2 was highly expressed in the TR HER2-positive breast cancer cell line. High expression level of NDUFA4L2 was associated with shorter relapse-free intervals in trastuzumab-treated HER2-positive breast cancer patients. Overexpression of NDUFA4L2 enhanced Warburg effects, enhanced aerobic glycolysis, reduced oxygen consumption, and lowered ROS production. Mechanistically, overexpression of NDUFA4L2 facilitated mitochondrial relocalization of HER2 and suppressed ROS production, thus rendering cancer cells more resistant to trastuzumab treatment.

Conclusions:

We identified NDUFA4L2 as a new biomarker and potential therapeutic target for TR HER2-positive breast cancer.

Casein kinase 2 inhibitor CX-4945 elicits an anti-Warburg effects through the downregulation of TAp73 and inhibits gastric tumorigenesis

Casein kinase 2 (CK2) has become a potential therapeutic target in gastric cancer; however, the underlying mechanism remains incompletely understood. TAp73, a structural homolog of the tumor suppressor p53, acts as a critical regulator of the Warburg effect. Recent study reveals that aberrant CK2 signaling is able to inhibit TAp73 function. Here we determine that TAp73 is overexpressed in AGS-1 but not in SNU-5 gastric cancer cell line as compared with normal gastric cells. In addition, we show that TAp73 expression is required for the maintenance of glucose uptake and lactate release in AGS-1 but not in SNU-5 gastric cancer cells. Importantly, the use of CX-4945, a selective inhibitor of protein kinase CK2, inhibits cell growth and invasion, and promotes cell apoptosis in AGS-1 with decreased TAp73 expression as well as downregulated glucose uptake and lactate release. Although TAp73 knockdown resulted in significant decreases in TAp73 expressions in SNU-5 cell line, no differences in glucose uptake and lactate release were observed between SNU-5 and normal gastric cells. Moreover, TAp73 gene overexpression promotes glucose uptake and lactate release and abolishes the anti-cancer effects of CX-4945 in gastric cancer cell line AGS-1. The impacts of CX-4945 on glycolysis and tumorigenesis were strongly limited in SNU-5 gastric cancer cell line. These findings suggest that CX-4945 elicits an anti-Warburg effects in gastric cancer overexpressing Tap73 and inhibits gastric tumorigenesis.

Targeting Cancer Metabolism - Revisiting the Warburg Effects

After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism.