Investigation of the role of asprosin and downstream glycolytic molecules in ovarian cancer

Abstract

Ovarian Cancer (OvCa) affects over 313,000 women globally, and is consistently defined as the most lethal form of gynaecological malignancy. Despite improvements to cancer biology and therapeutics, the arsenal to tackle OvCa has limitations, and there is still scope for better understanding of the disease. Augmented glycolysis and conversion of glucose to lactate within the tumour microenvironment (TME) is a process required for cell proliferation and long-term maintenance. Through investigation of the novel glucogenic hormone asprosin, this work presents evidence of a possible regulator of glycolysis within the TME and assesses the biomarker potential of glycolytic molecules in OvCa detection and the monitoring of progression. Asprosin is expressed in OvCa of varying stage and subtype, with high expression of predicted receptors OR4M1 and TLR4 also evident. OR4M1 shows promise as a biomarker of early stage OvCa with significant decline seen in later stages (p < 0.04). Similarly, both receptors were detected in cancer-associated circulating cells with a decline recorded for OR4M1 as treatment progressed (p < 0.0069). In addition, olfactory receptors were seen to co-localise in cancer with cell entry mediators for SARS-CoV-2 and their distraction might be implicated in the anosmia seen in many COVID-19 patients. Transcriptomic analyses revealed that asprosin can potentially influence integral cancer progressing pathways such as TGF-β, ROS and angiogenesis, plus the phosphorylation of the signalling molecule ERK 1/2 (p < 0.01). Additional work, highlights the biomarker potential of lactate; a signalling molecule and product of glycolysis in OvCa. Significantly elevated levels of lactate at rest were recorded, above the normal range of 0.2–2 mmol/L, in OvCa patients compared with controls (p<0.0001); with an area under curve (AUC) of 0.96. High lactate is seen regardless of treatment, age or BRCA status in OvCa patients. Moreover, RNA expression of the lactate receptor hydroxycarboxylic acid receptor 1 (HCAR1) is significantly upregulated in OvCa compared to controls (p < 0.001). HCAR1 showed widespread protein expression in OvCa patients including clear cell carcinoma (CCC), high grade serous carcinoma (HGSOC), low grade serous carcinoma (LGSOC), endometrioid adenocarcinoma (EAC), mucinous adenocarcinoma (MAC), lymph node metastasis (MET), and normal adjacent tissue (NAT). Concluding investigations sought the current landscape of OvCa models in the literature. Focusing on 3D culture it was found that OvCa cells grown in this manner were more representative of in vivo systems compared with conventional monolayer cultures. In addition, 3D OvCa culture showed an enhanced ability to mimic complex processes such as angiogenesis, drug resistance and cell signalling. This study provides novel evidence for the expression of an intact asprosin signalling pathway in OvCa both at tissue and liquid biopsy level. Additional evidence of the clinical utility of resting lactate levels for OvCa patients is also presented. Future studies should concentrate on the understanding of asprosin-receptor-mediated mechanisms, its role in metabolic changes and the potential biomarker utility of asprosin-related genes as well as lactate.