Although hypoxia has been shown to reprogram cancer cells toward glycolytic shift, the identity of extrinsic stimuli that induce metabolic reprogramming independent of hypoxia, especially in ovarian cancer, is largely unknown. In this study, we use patient-derived ovarian cancer cells and high-grade serous ovarian cancer cell lines to demonstrate that lysophosphatidic acid (LPA), a lipid growth factor and GPCR ligand whose levels are substantially increased in ovarian cancer patients, triggers glycolytic shift in ovarian cancer cells. Inhibition of the G protein α-subunit Gαi2 disrupted LPA-stimulated aerobic glycolysis. LPA stimulated a pseudohypoxic response via Rac-mediated activation of NADPH oxidase and generation of reactive oxygen species, resulting in activation of HIF1α. HIF1α in turn induced expression of glucose transporter-1 and the glycolytic enzyme hexokinase-2 (HKII). Treatment of mice bearing ovarian cancer xenografts with an HKII inhibitor, 3-bromopyruvate, attenuated tumor growth and conferred a concomitant survival advantage. These studies reveal a critical role for LPA in metabolic reprogramming of ovarian cancer cells and identify this node as a promising therapeutic target in ovarian cancer. These findings establish LPA as a potential therapeutic target in ovarian cancer, revealing its role in the activation of HIF1α-mediated metabolic reprogramming in this disease. .

Background: SARS-CoV-2 is a novel positive-sense single stranded RNA virus that has caused a recent pandemic. Most patients have a mild disease course, while approximately 20 percent have moderate-to-severe disease, often requiring hospitalization and, in some cases, care in the intensive care unit. Results: By investigating a perceived increased rate of indeterminate QuantiFERON®-TB Gold Plus results in hospitalized COVID patients, we demonstrate that severely ill COVID-19 patients have at least a 6-fold reduction of interferon-gamma (IFN-γ) levels compared to control patients. What is more, over sixty percent of these severely ill COVID-19 patients’ peripheral T-cells were found to be unable to produce measurable IFN-γ when stimulated with phytohemagglutinin (PHA), a potent IFN-γ mitogen, reflected by an indeterminate QuantiFERON®-TB Gold Plus. This defect of IFN-γ production was independent of absolute lymphocyte counts and immunosuppressive therapy. It was associated with increased levels of IL-6, which was a predictor of patient outcomes for our cohort when measured early in the course of disease. Finally, in a subset of COVID-19 patients, we found elevated IL-10 levels, in addition to IL-6 elevation. Conclusions: In addition to finding a significant limitation of IGRA testing severely ill COVID-19 patients, these data provide evidence that many of these patients demonstrate a focused Th2 immune response with inhibition of IFN-γ signaling and, in many cases, significant elevations of IL-6.

Recent studies have identified a critical role for lysophosphatidic acid (LPA) in the progression of ovarian cancer. Using a transcription factor activation reporter array, which analyzes 45 distinct transcription factors, it has been observed that LPA observed robustly activates the transcription factor hypoxia-induced factor-1α (HIF1α) in SKOV3.ip ovarian cancer cells. HIF1α showed 150-fold increase in its activation profile compared to the untreated control. Validation of the array analysis indicated that LPA stimulates a rapid increase in the levels of HIF1α in ovarian cancer cells, with an observed maximum level of HIF1α-induction by 4 hours. Our report demonstrates that LPA stimulates the increase in HIF1α levels via Gαi2. Consistent with the role of HIF1α in epithelial to mesenchymal transition (EMT) of cancer cells, LPA stimulates EMT and associated invasive cell migration along with an increase in the expression levels N-cadherin and Slug/Snail2. Using the expression of Slug/Snail2 as a marker for EMT, we demonstrate that the inhibition of Gαi2, HIF1α or Src attenuates this response. In line with the established role of EMT in promoting invasive cell migration, our data demonstrates that the inhibition of HIF1α with the clinically used HIF1α inhibitor, PX-478, drastically attenuates LPA-stimulates invasive migration of SKOV3.ip cells. Thus, our present study demonstrates that LPA utilizes a Gαi2-mediated signaling pathway via Src kinase to stimulate an increase in HIF1α levels and downstream EMT-specific factors such as Slug, leading to invasive migration of ovarian cancer cells.

Ovarian cancer is the most deadly gynecological cancer, with previous studies implicating lysophosphatidic acid (LPA) in the progression of approximately 90% of all ovarian cancers. LPA potently stimulates the tyrosine phosphorylation of p130Cas, a scaffolding protein, which, upon phosphorylation, recruits an array of signaling molecules to promote tumor cell migration. Our work presented here identifies Gα i2 as the major G protein involved in tyrosine phosphorylation of p130Cas in a panel of ovarian cancer cells consisting of HeyA8, SKOV3, and OVCA429. Our results also indicate that the G12 family of G proteins that are also involved in LPA-mediated migration inhibits tyrosine phosphorylation of p130Cas. Using p130Cas siRNA, we demonstrate that p130Cas is a necessary downstream component of LPA Gα i2 -induced migration and collagen-1 invasion of ovarian cancer cells. Considering the fact that LPA stimulates invasive migration through the coordination of multiple downstream signaling pathways, our current study identifies a separate unique signaling node involving p130Cas and Gα i2 in mediating LPA-mediated invasive migration of ovarian cancer cells.

Lysophosphatidic acid (LPA) plays a critical role in the migration and invasion of ovarian cancer cells. However, the downstream spatiotemporal signaling events involving specific G protein(s) underlying this process are largely unknown. In this report, we demonstrate that LPA signaling causes the translocation of Gαi2 into the invadopodia leading to its interaction with the tyrosine kinase Src and the Rac/CDC42-specific guanine nucleotide exchange factor, β-pix. Our results establish that Gαi2 activates Rac1 through a p130Cas-dependent pathway in ovarian cancer cells. Moreover, our report reveals that knockdown of Gαi2 leads to loss of β-pix and active-Rac association in the invadopodia. We also show that knockdown of Gαi2 leads to the complete loss of translocation to p130Cas to focal adhesions. Finally, when Gαi2 is knocked down, this led to the total distribution of Src being shifted primarily from invadopodia and the leading edge of the cells to the perinuclear region, suggesting that Src is inactive in the absence of Gαi2. Overall, our report provides tantalizing evidence that Gαi2 is a critical signaling component of a large signaling complex in the invadopodia that if disrupted could serve as an excellent target for therapy in ovarian and potentially other cancers.