ERO1α is a novel endogenous marker of hypoxia in human cancer cell lines

Abstract

Background Hypoxia is an important factor that contributes to tumour aggressiveness and correlates with poor prognosis and resistance to conventional therapy. Therefore, identifying hypoxic environments within tumours is extremely useful for understanding cancer biology and developing novel therapeutic strategies. Several studies have suggested that carbonic anhydrase 9 (CA9) is a reliable biomarker of hypoxia and a potential therapeutic target, while pimonidazole has been identified as an exogenous hypoxia marker. However, other studies have suggested that CA9 expression is not directly induced by hypoxia and it is not expressed in all types of tumours. Thus, in this study, we focused on endoplasmic reticulum disulphide oxidase 1α (ERO1α), a protein that localises in the endoplasmic reticulum and is involved in the formation of disulphide bonds in proteins, to determine whether it could serve as a potential tumour-hypoxia biomarker. Methods Using quantitative real-time polymerase chain reaction, we analysed the mRNA expression of ERO1α and CA9 in different normal and cancer cell lines. We also determined the protein expression levels of ERO1α and CA9 in these cell lines by western blotting. We then investigated the hypoxia-inducible ERO1α and CA9 expression and localisation in HCT116 and HeLa cells, which express low (CA9-low) and high (CA9-high) levels of CA9, respectively . A comparative analysis was performed using pimonidazole, an exogenous hypoxic marker, as a positive control. The expression and localisation of ERO1α and CA9 in tumour spheres during hypoxia were analysed by a tumour sphere formation assay. Finally, we used a mouse model to investigate the localisation of ERO1α and CA9 in tumour xenografts using several cell lines. Results We found that ERO1α expression increased under chronic hypoxia. Our results show that ERO1α was hypoxia-induced in all the tested cancer cell lines. Furthermore, in the comparative analysis using CA9 and pimonidazole, ERO1α had a similar localisation to pimonidazole in both CA9-low and CA9-high cell lines. Conclusion ERO1α can serve as a novel endogenous chronic hypoxia marker that is more reliable than CA9 and can be used as a diagnostic biomarker and therapeutic target for cancer. Electronic supplementary material The online version of this article (10.1186/s12885-019-5727-9) contains supplementary material, which is available to authorized users.

Tumor Microenvironment Status Predicts the Efficacy of Postoperative Chemotherapy or Radiochemotherapy in Resected Gastric Cancer

“…Moreover, stage Ib/ II fTME GC showed the highest mean hypoxia score and lowest RCT response score across all the subgroups in the pooled cohort (Figure 4B). We further validated our findings through a novel endogenous hypoxia marker-ERO1A (28) and observed that the TMEscore was positively correlated with the mRNA expression of ERO1A in all the cohorts (Figure 4C). Similar results were found for the mRNA expression of TS (Figure 4C)-the target of FU and an indicator of poor CT outcomespotentially in association with upregulation by hypoxia (21,29).…”

Endoplasmic reticulum oxidoreductase 1 alpha modulates prostate cancer hallmarks

“…Importantly, Ero 1α levels have been found correlated to PD-L1 expression in vitro and in vivo, suggesting Ero 1α as a potential target in cancer immunotherapy (20). Consistently with these evidences, Ero 1α has been found correlated with bad prognosis in different types of cancers, such as breast, pancreatic, cervical and gastric cancers (21)(22)(23)(24).…”

“…In particular, hypoxia is a frequent condition during tumorigenesis and a key feature of the tumor microenvironment (14). Ero 1α has been proposed as a marker of hypoxia in various kinds of cancers as it is induced by low-oxygenic environments via the hypoxiainducible factor 1 (HIF-1) (15). It also controls mRNA levels and folding of vascular endothelial growth factor A (VEGF-A), a molecule essential for neoangiogenesis (16).…”

Perineural Invasion and Postoperative Adjuvant Chemotherapy Efficacy in Patients With Gastric Cancer

“…In order to verify the hypoxia difference between PNI-positive and PNI-negative tumors, we detected the protein expression of ERO1A, a novel endogenous marker of hypoxia in cancer (29), in 49 GC tissues of the AHJU cohort (Figure 5C). The ERO1Apositive rate was significantly lower in PNI-positive tumors than in PNI-negative tumors (p = 0.015; Figure 5D).…”