Discovery, Structure-Activity Relationship and In Vitro Anticancer Activity of Small-Molecule Inhibitors of the...

Area of Science:

• Medicinal Chemistry
• Oncology
• Molecular Biology

Background:

• Chromosomal translocations involving the mixed lineage leukemia (MLL) gene are implicated in 5-10% of acute leukemias.
• Protein-protein interactions (PPI) involving MLL fusion partners (AF9/ENL, AF4) and DOT1L are key therapeutic targets in MLL-rearranged (MLL-r) leukemia.

Purpose of the Study:

• To identify novel inhibitors of PPIs between MLL fusion partners and DOT1L.
• To explore structure-activity relationships (SAR) of benzothiophene derivatives as potential MLL-r leukemia therapeutics.
• To evaluate the efficacy of identified compounds in inhibiting MLL target genes and leukemia cell proliferation.

Main Methods:

• Synthesis and screening of benzothiophene-carboxamide compounds for PPI inhibition.
• Structure-activity relationship (SAR) studies involving 77 benzothiophene, indole, and benzofuran derivatives.
• Assays to measure inhibition of MLL target gene expression (HoxA9, Meis1, Myc) and leukemia cell proliferation.

Main Results:

• Several benzothiophene-carboxamide compounds were identified as novel PPI inhibitors with IC50 values as low as 1.6 μM.
• SAR studies indicated that a 4-piperidin-1-ylphenyl or 4-pyrrolidin-1-ylphenyl substituent is essential for inhibitory activity.
• The most potent inhibitors suppressed MLL target gene expression and selectively inhibited MLL-r and other acute myeloid leukemia cell proliferation with EC50 values as low as 4.7 μM.

Conclusions:

• Benzothiophene-carboxamide derivatives represent a promising class of compounds targeting critical PPIs in MLL-r leukemia.
• These inhibitors serve as valuable chemical probes for studying MLL biology and as pharmacological leads for developing new leukemia therapies.