Growth-Inhibitory Effects of the Rare Sugar D-allose in Renal Cell Carcinoma In Vitro and In Vivo

Background/Aim: Rare sugars are naturally occurring monosaccharides present only in trace amounts. This study investigated their potential to inhibit the growth of renal cell carcinoma (RCC), a malignancy that remains challenging to treat despite advances in targeted therapies and immunotherapies. Materials and Methods: Human RCC cell lines, including Caki-1, Caki-2, and ACHN, were exposed to eight rare sugars representing key intermediates of the Izumoring biosynthetic pathway, along with four common sugars as controls. Cell viability was assessed using the MTT assay. To further characterize D-allose, intracellular uptake of D-allose was analyzed by high-performance liquid chromatography (HPLC), and its antitumor efficacy was assessed in a xenograft mouse model. Results: Among the sugars tested, D-allose reduced RCC cell viability across the tested concentrations. HPLC analysis detected intracellular D-allose in the examined RCC cells, supporting its intracellular availability under the experimental conditions. In vivo, D-allose significantly suppressed tumor growth in RCC xenograft-bearing mice without inducing apparent histological abnormalities in the liver or kidneys. Histopathological evaluation showed tumor necrosis as a qualitative observation in D-allose-treated tumors. Conclusion: These findings indicate that D-allose was detectable intracellularly in the examined RCC cells and inhibited RCC cell viability in vitro and tumor growth in vivo. Collectively, the results suggest that D-allose may represent a potential low-toxicity candidate for RCC therapy. Further studies are required to elucidate its molecular mechanisms, optimize dosing strategies, and evaluate its potential for clinical translation.