The O-acetyl (or
acetate) derivative of the Aspidosperma
alkaloid Jerantinine A (JAa) elicits anti-
tumor activity against
cancer cell lines including mammary
carcinoma cell lines irrespective of receptor status (0.14 < GI50 < 0.38 μM), targeting microtubule dynamics. By exploiting
breast cancer cells' upregulated
transferrin receptor 1 (TfR1) expression and
apoferritin (AFt) recognition, we sought to develop an AFt JAa-delivery vehicle to enhance
tumor-targeting and reduce systemic toxicity. Optimizing pH-mediated reassembly, ∼120 JAa molecules were entrapped within AFt. Western blot and flow cytometry demonstrate TfR1 expression in
cancer cells. Enhanced internalization of 5-carboxyfluorescein-conjugated human AFt in SKBR3 and MDA-MB-231
cancer cells is observed compared to MRC5 fibroblasts. Accordingly, AFt-JAa delivers significantly greater intracellular JAa levels to SKBR3 and MDA-MB-231 cells than naked JAa (0.2 μM) treatment alone. Compared to naked JAa (0.2 μM), AFt-JAa achieves enhanced growth inhibition (2.5-14-fold; <0.02 μM < GI50 < 0.15 μM) in
breast cancer cells; AFt-JAa treatment results in significantly reduced clonal survival, more profound cell cycle perturbation including G2/M arrest, greater reduction in cell numbers, and increased apoptosis compared to the naked agent (p < 0.01). Decreased PLK1 and Mcl-1 expression, together with the appearance of cleaved
poly (ADP-ribose)-polymerase, corroborate the augmented potency of AFt-JAa. Hence, we demonstrate that AFt represents a biocompatible vehicle for targeted delivery of JAa, offering potential to minimize toxicity and enhance JAa activity in TfR1-expressing
tumors.