Targeting glutamine metabolism combined with a nanoradioenhancer in radioresistant hepatocellular carcinoma

Abstract

Radiotherapy (RT) remains one of the curative modalities for localized hepatocellular carcinoma (HCC), exerting its therapeutic effect primarily through irradiation-induced oxidative stress and DNA damage in tumor cells. However, its efficacy is often constrained by intrinsic tumor resistance mechanisms and radiotoxicity in non-tumorous liver tissue. Metabolic reprogramming is a defining hallmark of tumor progression and therapeutic resistance. Recent advances in nanotechnology have facilitated integrated treatment approaches, particularly those combining RT with metabolic modulation, thereby achieving synergistic outcomes. Herein, we developed a nanoplatform using gold nanodandelions (GNDs@gelatin) as a nanoradioenhancer (NRE), loaded with 6-diazo-5-oxo-L-norleucine (DON), to form matrix metalloproteinase-triggered dual-functional RT/metabolic reprogramming nanoplatform, termed GNDs@gelatin/DON. This platform disrupts cellular redox homeostasis via dual mechanisms: enhancement of reactive oxygen species (ROS) generation and suppression of glutathione (GSH) biosynthesis. Cell proliferation inhibition was assessed using the Cell Counting Kit-8 (CCK-8) assay, while drug-radiation interactions were quantified using the CompuSyn software. In the HepG2/C3a RR cell line, the combination index (CI) of RT/GNDs@gelatin/DON (CI = 0.126) was markedly lower than that of RT/DON (CI = 0.395). A similar trend was observed in Huh7 RR cells (CI = 0.294 vs. CI = 0.462). These findings indicate that RT/GNDs@gelatin/DON achieved strong synergism (CI < 0.3), whereas RT/DON exhibited only moderate synergy (0.3 < CI < 0.7). Mechanistically, this dual-functional strategy not only augmented DNA damage, but also triggered mitochondrial dysfunction, leading to greater inhibition of cell proliferation in radioresistant HCC cells than either treatment alone. Importantly, GNDs@gelatin/DON demonstrated controlled DON release and reduced gastrointestinal (GI) toxicity compared with free DON. Collectively, our physical and biological evidence suggests that the synergistic inhibition of glutamine metabolism and GND-enhanced ROS production, in conjunction with MV photon irradiation, holds promise for improving the therapeutic efficacy of clinical radiotherapy.