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Increased microRNA in breast cancer cells linked to trastuzumab resistance
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In patients with breast cancer, increased expression of the microRNA miR-21 and reduced PTEN expression were associated with more resistance to trastuzumab than control cells, according to findings from a study.
In another study conducted by researchers from The University of Texas M.D. Anderson Cancer Center, published findings showed that PTEN loss was linked to trastuzumab (Herceptin, Genentech) resistance. Researchers from the same group conducted the current study to determine the relationship between miR-21/PTEN expression and trastuzumab resistance.
“This study potentiates the use of miR-21 and PTEN expression as biomarkers to determine patients who may or may not respond to trastuzumab treatment; it could help spare those patients the unnecessary treatment and the toxicity that comes with it,” Sumaiyah K. Rehman, third-year graduate student in the lab of Dihua Yu, MD, PhD, said during a press conference.
Yu is Hubert L. and Olive Stringer distinguished chair in basic science; professor and deputy chair of the department of molecular and cellular oncology; and director of the cancer biology program at M.D. Anderson Cancer Center.
When examining breast cancer cell lines, the researchers found that cells with increased miR-21 also had reduced PTEN expression and were more resistant to trastuzumab than control cells. When miR-21 was knocked down, cells increased PTEN expression and became more sensitive to the drug.
Next, they examined miR-21 expression in patients with breast cancer with ErbB2 expression. In these patients treated with trastuzumab, they confirmed that miR-21 levels were associated with patient response to the drug.
The findings of this study highlighted one mechanism by which miR-21 could affect trastuzumab resistance and exemplified that tumors can develop resistance, according to Rehman.
“MiRNAs have been reported to control up to 35% of our genome, so there are many discoveries remaining,” Rehman said in a press release. “This is one drop of information in the bucket of knowledge that is hardly full in what we can learn.”
For more information:
- Rehman SK. #4033. Presented at: AACR 101st Annual Meeting; April 17-21; Washington, D.C.