Investigating the NRAS 5' UTR as a target for small molecules
Sumirtha Balaratnam1, Zachary R Torrey1, David R Calabrese1
1Chemical Biology Laboratory, National Cancer Institute, Frederick, MD 21702, USA.
Abstract:
Neuroblastoma RAS (NRAS) is an oncogene that is deregulated and highly mutated in cancers including melanomas and acute myeloid leukemias. The 5' untranslated region (UTR) (5' UTR) of the NRAS mRNA contains a G-quadruplex (G4) that regulates translation. Here we report a novel class of small molecule that binds to the G4 structure located in the 5' UTR of the NRAS mRNA. We used a small molecule microarray screen to identify molecules that selectively bind to the NRAS-G4 with submicromolar affinity. One compound inhibits the translation of NRAS in vitro but showed only moderate effects on the NRAS levels in cellulo. Rapid Amplification of cDNA Ends and RT-PCR analysis revealed that the predominant NRAS transcript does not possess the G4 structure. Thus, although NRAS transcripts lack a G4 in many cell lines the concept of targeting folded regions within 5' UTRs to control translation remains a highly attractive strategy.
Insights
Researchers identified small molecules targeting the NRAS oncogene
Area of Science:
- Molecular Biology
- Oncology
- Drug Discovery
Background:
- Neuroblastoma RAS (NRAS) is a key oncogene frequently mutated in cancers like melanoma and acute myeloid leukemia.
- The 5' untranslated region (UTR) of NRAS mRNA contains a G-quadruplex (G4) structure implicated in translational regulation.
Purpose of the Study:
- To discover novel small molecules that selectively bind to the NRAS G4 structure.
- To investigate the potential of targeting the NRAS 5' UTR G4 for cancer therapy.
Main Methods:
- Small molecule microarray screening was employed to identify NRAS-G4 binders.
- In vitro translation assays and cell-based studies were conducted.
- Rapid Amplification of cDNA Ends (RACE) and RT-PCR were used to analyze NRAS transcript variants.
Main Results:
- A novel class of small molecules with submicromolar affinity for the NRAS-G4 was identified.
- One compound demonstrated in vitro inhibition of NRAS translation, but with moderate in vivo effects.
- Analysis revealed that the predominant NRAS transcript lacks the G4 structure in many cell lines.
Conclusions:
- Targeting structured regions within 5' UTRs is a promising strategy for controlling gene translation.
- Despite the absence of the G4 in many NRAS transcripts, the principle of targeting 5' UTRs for translational control remains viable.
- Further research into NRAS transcript variants and alternative regulatory mechanisms is warranted.
