Potent-by-design : amino acids mimicking porous nanotherapeutics with intrinsic anticancer targeting properties

Abstract

Exogenous sources of amino acids are essential nutrients to fuel cancer growth. Here, the increased demand for amino acid displayed by cancer cells is unconventionally exploited as a design principle to replete cancer cells with apoptosis inducing nanoscopic porous amino acid mimics (Nano-PAAM). A small library consisting of nine essential amino acids nanoconjugates (30 nm) are synthesized, and the in vitro anticancer activity is evaluated. Among the Nano-PAAMs, l-phenylalanine functionalized Nano-PAAM (Nano-pPAAM) has emerged as a novel nanotherapeutics with excellent intrinsic anticancer and cancer-selective properties. The therapeutic efficacy of Nano-pPAAM against a panel of human breast, gastric, and skin cancer cells could be ascribed to the specific targeting of the overexpressed human large neutral amino acid transporter SLC7A5 (LAT-1) in cancer cells, and its intracellular reactive oxygen species (ROS) inducing properties of the nanoporous core. At the mechanistic level, it is revealed that Nano-pPAAM could activate both the extrinsic and intrinsic apoptosis pathways to exert a potent "double-whammy" anticancer effect. The potential clinical utility of Nano-pPAAM is further investigated using an MDA-MB-231 xenograft in NOD scid gamma mice, where an overall suppression of tumor growth by 60% is achieved without the aid of any drugs or application of external stimuli.