Failure of Efforts to Block miR-17 in Triple-Negative Breast Cancer Explained; Guide & Passenger Strands of miR-17 Both Active in Suppressing Tumor Suppressor Genes PDCD4 and PTEN; New Efforts Will Target miR-17 Without Imitating Passenger Strand

Researchers at Thomas Jefferson University in Philadelphia, Pennsylvania have discovered why conventional efforts to block a tiny strand of ribonucleic acid, called microRNA, in triple-negative breast cancer cells failed. In a study published online today (December 2, 2015) in the open-access journal PLOS ONE, the new insight may enable effective design of RNA blockers against previously intractable microRNAs. The new report is titled “Non-Specific Blocking of Mir-17-5p Guide Strand in Triple Negative Breast Cancer Cells by Amplifying Passenger Strand Activity.” “Triple-negative breast cancer is one of the most aggressive forms of breast cancer, and there's been a lot of excitement in blocking the microRNAs that appear to make this type of cancer grow faster and resist conventional treatment," says senior author Eric Wickstrom, Ph.D., a Professor in the Department of Biochemistry and Molecular Biology at the Sidney Kimmel Medical College (SKMC) at Thomas Jefferson University. "However blocking microRNAs hasn't met with great success and this paper offers one explanation for why that might be the case." "Triple-negative breast cancer strikes younger women, tragically killing them in as little as two years," says first author Yuan-Yuan Jin, a Ph.D. candidate in the SKMC Department of Biochemistry and Molecular Biology. "Only chemotherapy and radiation are approved therapies for triple-negative breast cancer. We want to treat a genetic target that will keep patients alive with a good quality of life." The researchers targeted a microRNA called miR-17 that is known to spur triple-negative breast cancer growth by interfering with genes that would normally signal a diseased or early-cancerous cell to die. Specifically, miR-17 blocks the tumor suppressor genes PDCD4 and PTEN. However, when Ms.
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