RNA Targeting in Acute Myeloid Leukemia

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Nucleoside analogues are vital anticancer agents.
• Cytarabine (ara-C) has been a primary treatment for acute myeloid leukemia (AML) with DNA as its presumed target since the 1980s.

Purpose of the Study:

• To investigate the biomolecular targets of ara-C in primary white blood cells.
• To evaluate the incorporation of an ara-C mimic (AzC) into cellular components.
• To explore the clinical implications of differential drug incorporation in AML patients.

Main Methods:

• Utilized azide-alkyne
• click
• reactions with an ara-C mimic (AzC).
• Employed fluorescent staining, microscopy, RNaseH digestion, and pull-down-and-release assays.
• Analyzed samples from healthy donors and AML patients (FAB classes M4 and M5).

Main Results:

• Metabolic incorporation of AzC into white blood cells was enhanced by aphidicholine, a DNA polymerase inhibitor.
• AzC was incorporated into RNA fragments bound to DNA in healthy donor PBMCs.
• AML patient samples showed heterogeneity: 27% incorporated AzC into RNA, 55% into DNA.
• Patients incorporating AzC into RNA had a ~3-fold higher overall survival compared to the DNA cohort (p ≤ 0.056).

Conclusions:

• RNA primers of DNA synthesis represent a clinically favorable target for ara-C.
• Differential incorporation of nucleoside drugs into DNA versus RNA may allow for patient stratification into tailored treatment subgroups.
• This research opens new avenues for personalized medicine in AML treatment.