Researchers discover biomarkers that may lead to first blood test to detect renal cell carcinomas

A simple blood test measuring levels of two microRNAs—miR-651 and miR-708—may become a viable and simple screening test for renal cell carcinoma, and these two biomarkers may also be the basis for future new treatments, according to study results presented at the 69^th American Association for Clinical Chemistry (AACC) Annual Scientific Meeting & Clinical Lab Expo.

“The mechanisms involved in renal cell carcinoma development and progression are unclear, and there is no standard serological biomarker to facilitate diagnosis in patients with [this disease],” said Chunni Zhang, PhD, Jinling Hospital, Nanjing, China. “miR-651 and miR-708 may potentially serve as novel biomarkers for renal cell carcinoma and may act as tumor suppressors. Our findings indicate that targeting miR-651 and miR-708 by a genetic approach may provide a novel strategy for the treatment of renal cell carcinoma.”

Patients with renal cell carcinoma can be asymptomatic, and thus are at highest risk for a diagnosis only in a more advanced stage of cancer. After diagnosis, 81% of patients with stage 1 renal cell carcinoma survive for 5 years, but this drops to 53% for those with stage III disease.

Dr. Zhang and fellow researchers sought to assess whether microRNAs were useful in detecting kidney cancer, especially in patients with asymptomatic tumors. In 33 patients with renal cell carcinoma, they measured concentrations of 754 different microRNAs in serum samples.

Levels of eight of these microRNAs were either significantly increased (4) or decreased (4) in kidney cancer patients compared with healthy controls. Of these eight, miR-651 and miR-708 were decreased in kidney cancer patients and had the largest AUCs (0.888 [95% CI 0.833-0.943] and 0.832 [95% CI 0.786-0.878], respectively). Therefore, a test for miR-651 and miR-708 may have a relatively high accuracy in diagnosing renal cell carcinoma.

Using Luciferase reporter assays and Western blotting, Dr. Zhang and colleagues also found that miR-651 and miR-708 may act as tumor suppressors via direct regulation of RAP1B, a Ras-related small GTP-binding oncoprotein implicated in several tumors. Thus, increasing concentrations of these two microRNAs may, potentially, become a new avenue for the development of new treatments for renal cell carcinoma.