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After decades of efforts, researchers have finally found a way to silence a mutated gene implicated in 30 percent of human cancers.

The KRAS oncogene is implicated in lung, colon, pancreatic and thyroid cancers. It was among the first oncogenes discovered but efforts to target it only yielded limited results. One of the difficulties in targeting it includes the KRAS's proteins structure, which with few pockets, does not allow for easy drug binding.  

"KRAS was one of the first cancer-causing genes ever discovered, and it was the obvious target to go after. People have been trying for decades to hit it, but they haven't had much luck. It has been widely regarded as an undruggable protein, but we show that that's simply not the case," said Chad Pecot, assistant professor of medicine at University of Carolina at Chapel Hill and the study's lead author in a press release.

Pecot and his team of researchers used a specifically sequence type of small interfering RNA also called siRNA, to block KRAS oncogene. The siRNA binds to message RNA or mRNA which carries information for production of proteins. After binding to KRAS mRNA, siRNA direct enzymes to destroy mRNA. Pecot and his team found two siRNA molecules suitable for the job.

In culture studies, they found siRNA bound to KRAS mRNA and resulted in destruction of 90 percent KRAS mRNAS to reduce tumor cell growth. When the team conducted studies in mice with colon cancer models, they found a 63 percent reduction in tumor growth. They also found that siRNAs reduced metastasis of cancer by 80 percent in mice with lung cancer.  

While significant, the use of siRNAs in humans would have to wait until researchers find a way to make them target mutated KRAS, leaving healthy activity intact.

The study has been published in the journal Molecular Cancer Therapeutics.