Extracellular Vesicle Transmission of Chemoresistance to Ovarian Cancer Cells Is Associated with Hypoxia-Induced Expression of Glycolytic Pathway Proteins, and Prediction of Epithelial Ovarian Cancer Disease Recurrence

Abstract

Hypoxia is a key regulator of cancer progression and chemoresistance. Ambiguity remains about how cancer cells adapt to hypoxic microenvironments and transfer oncogenic factors to surrounding cells. In this study, we determined the effects of hypoxia on the bioactivity of sEVs in a panel of ovarian cancer (OvCar) cell lines. The data obtained demonstrate a varying degree of platinum resistance induced in OvCar cells when exposed to low oxygen tension (1% oxygen). Using quantitative mass spectrometry (Sequential Window Acquisition of All Theoretical Fragment Ion Mass Spectra, SWATH) and targeted multiple reaction monitoring (MRM), we identified a suite of proteins associated with glycolysis that change under hypoxic conditions in cells and sEVs. Interestingly, we identified a differential response to hypoxia in the OvCar cell lines and their secreted sEVs, highlighting the cells’ heterogeneity. Proteins are involved in metabolic reprogramming such as glycolysis, including putative hexokinase (HK), UDP-glucuronosyltransferase 1–6 (UD16), and 6-phosphogluconolactonase (6 PGL), and their presence correlates with the induction of platinum resistance. Furthermore, when normoxic cells were exposed to sEVs from hypoxic cells, platinum-resistance increased significantly (p < 0.05). Altered chemoresistance was associated with changes in glycolysis and fatty acid synthesis. Finally, sEVs isolated from a clinical cohort (n = 31) were also found to be enriched in glycolysis-pathway proteins, especially in patients with recurrent disease. These data support the hypothesis that hypoxia induces changes in sEVs composition and bioactivity that confers carboplatin resistance on target cells. Furthermore, we propose that the expression of sEV-associated glycolysis-pathway proteins is predictive of ovarian cancer recurrence and is of clinical utility in disease management.

Malignant Ascites in Ovarian Cancer: Cellular, Acellular, and Biophysical Determinants of Molecular Characteristics and Therapy Response

“…Authors also reported that platinum-resistance significantly increased in normoxic cells when exposed to EVs secreted by hypoxic cells [246]. When tumor-derived EVs were isolated from patients with ovarian cancer, Alharbi et al found similar results in that they contained glycolytic pathway-related proteins and were most enriched in patients with recurrent disease [246]. These findings suggest that EVs containing glycolytic pathway-related proteins can transmit chemoresistance to other tumor cells, facilitating the progression of disease [246].…”

“…Hypoxia-related proteins that were examined were mainly involved in metabolic reprogramming, specifically relating to the glycolytic pathway. Authors also reported that platinum-resistance significantly increased in normoxic cells when exposed to EVs secreted by hypoxic cells [246]. When tumor-derived EVs were isolated from patients with ovarian cancer, Alharbi et al found similar results in that they contained glycolytic pathway-related proteins and were most enriched in patients with recurrent disease [246].…”

“…The role of tumor-derived extracellular vesicle (EV) secretion in ovarian cancer progression and response to therapy, was examined by Alharbi et al [246]. It was observed that low oxygen tension led to an increase in the expression of hypoxia-related proteins and induced EV release.…”

Ovarian-Cancer-Associated Extracellular Vesicles: Microenvironmental Regulation and Potential Clinical Applications

“…Tumor growth and survival depends upon microenvironmental conditions that promote metabolic reprogramming, angiogenesis and cellular invasion [ 33 , 34 ]. The extracellular matrix (ECM) and stromal cell types participate in the development of an appropriate microenvironmental niche.…”

Characterizing Endocrine Status, Tumor Hypoxia and Immunogenicity for Therapy Success in Epithelial Ovarian Cancer

“…One of the mechanisms by which hypoxia induces chemoresistance is through alteration of cancer cell metabolism. In response to hypoxia, ovarian cancer cells undergo a metabolic switch, with changes in the glycolytic pathway that promotes resistance to carboplatin (142)(143)(144). As ovarian tumors become hypoxic, there is an upregulation of glycolytic enzymes to metabolize glucose, resulting in the formation of lactate (145).…”