Serum level and tumor tissue expression of Ribonucleotide-diphosphate Reductase subunit M2 B: a potential biomarker for colorectal cancer.

Abstract

This study explored the applicability of serum level and tissue expression of Ribonucleotide-diphosphate Reductase subunit M2 B (RRM2B) as reliable biomarkers for colorectal cancer (CRC) progression and metastasis. The present descriptive-analytic cohort study was conducted on 50 newly diagnosed CRC patients (stage II, III) and 50 healthy individuals. The new cases had not received any therapeutic intervention and underwent surgery immediately after the initial diagnosis. Tumorous tissues and marginal healthy tissues (as control) were excised to determine the mRNA tissue expression of RRM2B by Real-Time PCR. Serum RRM2B protein was measured using an ELISA method once in the control group. In the patients, serum RRM2B protein was evaluated before, 1 and 3 months after surgery. The tumor metastasis node (TMN) classification system and liver metastasis were evaluated in CRC patients. The results showed significantly lower RRM2B serum levels in 1 and 3 months after surgery compared with the pre-surgery condition (P = 0.014, P < 0.001 respectively). The mean RRM2B gene expression was 51% lower in tumor tissue than its adjacent normal tissue (P < 0.001). No significant relationship was found between serum level of RRM2B and tumor staging and metastasis in patients before surgery (P = 0.373, P = 0.189), 1 month after surgery (P = 0.960, P = 0.088), and 3 months after surgery (P = 0.407, P = 0.724). RRM2B expression in tumor tissue is not associated with tumor staging and metastasis (P = 0.254, P = 0.721). These data suggest measuring serum protein level of RRM2B could have a role in CRC progression, although this study should be considered preliminary due to small sample size and short follow-up duration.