RAS-Targeted Drug Discovery: From Challenge to Opportunity

cancer cell, ras-targeted drug discovery

In 1963, Jennifer Harvey was studying Moloney murine leukemia virus (MMLV) at the cancer research department of the London Hospital Research Laboratories. After routine transfers of plasma from MMLV-infected rats to mice, she made an unusual discovery. In addition to the expected leukemia, the mice that received the plasma developed solid tumors (soft-tissue sarcomas), primarily in the spleen (1). A few years later, Werner Kirsten at the University of Chicago observed similar results working with mouse erythroblastosis virus (MEV) (2).

Subsequent research, with the advent of genome sequencing, showed that a cellular rat gene had been incorporated into the viral genome in both cases (3). These genomic sequences contained a mutation later shown to be responsible for the development of sarcomas, and the word “oncogene” became a common part of the vocabulary in cancer publications during the early 1980s (4). Harvey’s discovery led to the naming of the corresponding rat sarcoma oncogene as HRAS, while Kirsten’s related oncogene was named KRAS. Several laboratories, working independently, cloned the human homolog of the viral HRAS gene in 1982 (3). The human KRAS gene was cloned shortly thereafter, as well as a third RAS gene, named NRAS (3). Additional studies showed that a single point mutation in each of these genes led to oncogenic activation, and they have been popular targets for anticancer drug discovery efforts ever since.

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Paving New Ways for Drug Discovery & Development: Targeted Protein Degradation

The Dana-Farber Targeted Protein Degradation Webinar Series discusses new discoveries and modalities in protein degradation.

In this webinar, Senior Research Scientist, Dr. Danette Daniels, focuses primarily on proteolysis-targeting chimeras, or PROTACs. A variety of topics are covered including the design, potency, and efficacy of PROTACs in targeted protein degradation. Watch the video below to learn more about how PROTACs are shifting perspectives through fascinating research and discoveries in targeted protein degradation.

Learn more about targeted protein degradation and PROTACS here.

Designing BET(ter) Inhibitors to Guide Therapy for Cancer and Inflammatory Diseases

bet proteins brd nanoluc

Transcriptional activation of genes within the nucleus of eukaryotic cells occurs by a variety of mechanisms. Typically, these mechanisms rely on the interaction of regulatory proteins (transcriptional activators or repressors) with specific DNA sequences that control gene expression. Upon DNA binding, regulatory proteins also interact with other proteins that are part of the RNA polymerase II transcriptional complex.

One type of transcriptional activation relies on inducing a conformational change in chromatin, the DNA-protein complex that makes up each chromosome within a cell. In a broad sense, “extended” or loosely wound chromatin is more accessible to transcription factors and can signify an actively transcribed gene. In contrast, “condensed” chromatin hinders access to transcription factors and is characteristic of a transcriptionally inactive state. Acetylation of lysine residues in histones—the primary constituents of the chromatin backbone—results in opening up the chromatin and consequent gene activation. Disruption of histone acetylation pathways is implicated in many types of cancer (1).

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PROTACs, PHOTACs and LYTACs: How to Target a Protein for Degradation

PROTACs for Targeted Protein Degradation
An illustration of PROTAC structure and the proteins it binds.

Targeting a single protein and making it disappear from the cell is quite the magic trick, and there are various molecular tools available for this task. You can use RNA interference, which prevents a protein from being made, inhibitors that bind the protein, rendering it unavailable for use or even gene editing tools like CRISPR that can remove it from the genome. But did you know that you can target an existing protein for destruction, using the cell’s own garbage disposal system to degrade the protein? All you need is a molecule that can connect your protein to one with a role in cellular protein degradation and your protein can be destroyed.

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