Targeting KRAS Regulation with PolyPurine Reverse Hoogsteen Oligonucleotides

Area of Science:

• Molecular Biology
• Genetics
• Cancer Therapeutics

Background:

• KRAS is a GTPase crucial for growth factor signaling and cell proliferation.
• The KRAS gene contains G-rich regions with potential G-quadruplex (G4) forming sequences.
• Stabilization of the G4_mid structure in the KRAS promoter downregulates transcription; other G4s' roles are unknown.

Purpose of the Study:

• To identify and characterize G4-forming sequences (G4FS) within the KRAS gene.
• To develop and test Polypurine Reverse Hoogsteen hairpins (PPRHs) targeting KRAS G4s.
• To evaluate the therapeutic potential of PPRHs in downregulating KRAS and inhibiting cancer cell proliferation.

Main Methods:

• Identification of three putative G4FS in the KRAS gene.
• Design and synthesis of five PPRHs targeting G4_mid and other G4FS.
• Confirmation of PPRH binding, assessment of KRAS transcription via luciferase assays and qRT-PCR, and evaluation of cytotoxicity in cancer cells.

Main Results:

• PPRHs were confirmed to bind to target G4 sequences.
• PPRHs decreased KRAS promoter activity and selectively suppressed proliferation in KRAS-dependent cancer cells.
• PPRHs showed synergistic effects with a known KRAS G4-stabilizing compound in pancreatic cancer cells.

Conclusions:

• PPRHs selectively stabilize G4 formation within the KRAS mid promoter region.
• PPRHs represent an innovative approach for KRAS modulation.
• Targeting KRAS G4 structures with PPRHs holds potential for novel cancer therapeutics.