Increased ENT2 expression and its association with altered purine metabolism in cell lines derived from different stages of colorectal cancer

Abstract

Colorectal cancer (CRC) is one of the most prevalent malignant cancer types worldwide. Although the purine metabolism pathway is vital for cancer cell survival, little is known about the role of equilibrative nucleoside transporter 2 (ENT2) in CRC development and its association with purine metabolites. The aim of the present study was to evaluate the levels of hypoxanthine phosphoribosyl transferase (HPRT), hypoxanthine and uric acid (UA), as well as xanthine oxidase (XO) activity, and investigate their association with ENT2 expression levels in a normal human colon cell line and CRC cell lines derived from different stages of CRC. These analyses were performed using the normal colon CCD-841CoN cell line and a panel of human CRC cell lines comprising SW480, HCT15 and HCT116, which represent Dukes' B, C and D stages, respectively. Reverse transcription-quantitative PCR was performed to determine the level of ENT2 mRNA expression. In cells of all CRC stages, the levels of HPRT and hypoxanthine were significantly higher (P<0.05), while XO activity and UA levels were significantly decreased (P<0.05), compared with those in the CCD-841CoN cell line. ENT2 expression was found to be elevated in cells derived from all stages of CRC. The Dukes' D stage cell line had higher levels of HPRT and hypoxanthine, although its ENT2 level was not significantly lower than that of the Dukes' B and C stage cell lines. Increased levels of HPRT and hypoxanthine in various stages of CRC may indicate an increase in the activity of the salvage pathway. The increased expression of ENT2 implies the importance of the ENT2 protein in facilitating hypoxanthine transport, which is required for enhanced DNA synthesis via hypoxanthine recycling. In conclusion, ENT2 may have potential as a target in the development of CRC therapeutics.

1H-NMR metabolomics analysis identifies hypoxanthine as a novel metastasis-associated metabolite in breast cancer

“…Consistent with these data, high levels of hypoxanthine were recently identified as biomarker in human melanoma metastasis 31 , lung squamous cell carcinoma metastasis 32 and prostate cancer aggressiveness 33 . Similarly, the highest level of hypoxanthine was reported in stage IV compared to stage II and III, indicating its role in colorectal cancer progression 34 . These reports may further support the role of hypoxanthine in cancer metastasis.…”

“…During the purine catabolism pathway, hypoxanthine is converted to xanthine, which is then converted to uric acid by xanthine oxidase (XOR). This is associated with the production of ROS as by-product 34 . It has been demonstrated that the loss of XOR expression is associated with aggressiveness in breast cancer 39 .…”

A decision support system to recommend appropriate therapy protocol for AML patients

“…The high expression of SLC29A2 , also known as ENT2 , suggests its importance in facilitating hypoxanthine transport, which is necessary for enhanced DNA synthesis through hypoxanthine recycling. In conclusion, ENT2 shows potential as a target for developing therapeutics (Naes et al, 2023 ). Elevated levels of ENT2 in the blasts at the time of diagnosis of AML were associated with a lower response to induction therapy (Rodríguez-Macías et al, 2023 ).…”

UHPLC-HRMS-based Multiomics to Explore the Potential Mechanisms and Biomarkers for Colorectal Cancer

“…As tissue biopsy is invasive and relatively difficult, we chose human CRC cell lines as the subject of our study. CRC cell lines were classified based on Dukes’ classification criteria by ATCC and previous studies [ 15 , 23 ]. The Dukes’ staging system classifies CRC into four groups known as Dukes’ A, B, C, and D groups, which represent stages I, II, III, and IV of CRC.…”