Carica papaya L. Hexane Fraction Induces Apoptotic Cell Death in Colorectal Cancer Cells via PI3K/AKT Suppression and Impaired Late-Stage Autophagic Flux

Background/Objectives: Colorectal cancer (CRC) remains a major contributor to cancer-associated deaths globally. Carica papaya L., a tropical fruit species, is reported to contain a wide range of biological properties, along with potential anticancer effects. However, studies evaluating the therapeutic potential and molecular mechanisms of Korean Carica papaya L. cultivars against CRC are limited. Therefore, this study investigated the effect of the hexane fraction of Carica papaya L. on the induction of apoptosis and the underlying mechanisms associated with this effect in human CRC cells. Methods: We performed several in vitro experiments, including cell viability, apoptosis, assessment of autophagic vacuoles, Western blotting, and analysis of autophagic flux. Subsequently, we verified the findings in an animal model of CRC induced by azoxymethane/dextran sulfate sodium. Results: BR 56 Hex F reduced cell viability and induced caspase-7/9-dependent apoptosis accompanied by intracellular and mitochondrial reactive oxygen species elevation. Mechanistically, BR 56 Hex F suppressed phosphatidylinositol 3-kinase (PI3K; p85/p110), p-AKT (Ser473/Thr308), and mammalian target of rapamycin signaling. Although autophagosome formation was initiated, the late-stage autophagic flux was impaired, as evidenced by p62 accumulation, LAMP-1 depletion, and autophagosome accumulation. In vivo, oral administration of BR 56 C. papaya L. extract significantly attenuated azoxymethane/dextran sulfate sodium-induced colon shortening, splenomegaly, histopathological damage, and colonic PI3K and p-AKT expression. Conclusions: BR 56 Hex F inhibited CRC growth by suppressing PI3K/AKT signaling and impairing late-stage autophagic flux, representing a potential natural candidate for CRC treatment.