German Researchers Find Sensitizer for Gemcitabine Using DECIPHER RNAi Libraries

Researchers for the German Cancer Research facility (DKFZ) used Cellecta’s shRNA DECIPHER libraries to spot genes that sensitize pancreatic cells to gemcitabine.

Pancreatic cancer only has a 6% 5-year survival rate. Gemcitabine could be the standard treatment in partnership with surgery to take out cancerous pancreatic tissue from the minority with the cases when the ailment is caught in time. However, the gemcitabine response rate is below 20%, and combinations with targeted drugs are yet to improved this significantly until now.

To deal with this treatment problem, Dr. Michael Boettcher’s group at DKFZ used DECIPHER short-hairpin RNA (shRNA) libraries running loss-of-function genetic screens on pancreatic cancer cells to spot genes that enable cells to resist gemcitabine-induced lethality. They screened cellular structure with both DECIPHER Library Modules 1 and a couple of which target approximately 10,000 human genes in whole. Each lentiviral-based library module consists of 27,500 shRNA expression constructs targeting approximately 5,000 human genes—each gene targeted by 5-6 hairpins.

To run the screens, cells were transduced while using libraries then helped by gemcitabine with the goal to name genes that, when knocked down, made the cell weaker to gemcitabine. Interference using the function of those genes, then, would seem to become synthetically lethal with gemcitabine. Thus, these genes could be good potential targets for the combination treatment while using drug.

Inside the screening, they identified about 70 genes with synthetic lethal effects in conjunction with gemcitabine. Highly represented inside the hits were genes interested in DNA damage response and repair, which was expected since gemcitabine is often a DNA damaging agent. They focused specifically on genes identified within the screen that had been upstream from the checkpoint kinase 1 (CHK1) of the ATR/CHK1 pathway. Specifically, RAD17, HUS1, WEE1, and RFC3 all resulted in within the screen, and but RCF3 were subsequently confirmed with 3 independent shRNA constructs.

All of those other study dedicated to the RAD17 gene. They demonstrated that knocking down this gene increased lethality of gemcitabine by forcing cells with damaged DNA to get in mitosis. The same effect was shown previously for WEE1 by Aarts, et alii., that is also identified from the screen. In point of fact, a potent inhibitor of WEE1 kinase (MK-1775) is scheduled in conjunction with gemcitabine and platinum-based drugs for phase I clinical tests.

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