Structure-activity relationship study to improve cytotoxicity and selectivity of lonafarnib against breast cancer...

Area of Science:

• Medicinal Chemistry
• Cancer Biology
• Pharmacology

Background:

• Lonafarnib is a farnesyltransferase (FTase) inhibitor with broad anti-tumor activity.
• Its clinical utility is limited by unselective activity and high cytotoxicity against nonmalignant cells.

Purpose of the Study:

• To structurally modify lonafarnib to enhance selectivity for cancer cells.
• To evaluate the antiproliferative effects of novel lonafarnib derivatives on breast cancer and fibroblast cell lines.

Main Methods:

• Chemical synthesis of lonafarnib derivatives by modifying the terminal 4-methylpiperidine-1-carboxamide residue.
• In vitro antiproliferative assays using MCF-7 breast cancer cells and SV-80 fibroblasts.
• Determination of half-maximal inhibitory concentrations (IC50).
• Molecular modeling studies to investigate potential interactions with FTase.

Main Results:

• Two derivatives, piperidin-4-yl carbamate 15i and S-(piperidin-4-yl) carbamothioate 15j, exhibited high cytotoxicity against both cell lines (IC50 ≈ 2 µM).
• The 1-cyclohexyl-1-methylurea derivative 15b demonstrated selectivity, inhibiting MCF-7 cells (IC50 = 11.4 µM) with minimal effect on SV-80 cells (IC50 > 50 µM).
• Molecular modeling did not fully explain the observed biological activity, showing comparable binding of active and inactive compounds.

Conclusions:

• Structural modification of lonafarnib can lead to derivatives with improved selectivity for cancer cells.
• Derivative 15b represents a promising candidate for targeted breast cancer therapy.
• Further studies are needed to elucidate the precise mechanisms underlying the observed selectivity and activity.