Triple-negative breast cancer (TNBC) cells overexpress the epidermal growth factor receptor (EGFR). Nuclear EGFR (nEGFR) drives resistance to anti-EGFR therapy and is correlated with poor survival in breast cancer. Inhibition of EGFR nuclear translocation may be a reasonable approach for the treatment of TNBC. The anti-malarial drugs chloroquine and primaquine have been shown to promote an anticancer effect. The aim of the present study was to investigate the effect and mechanism of chloroquine- and primaquine-induced apoptosis of breast cancer cells. We showed that primaquine, a malaria drug, inhibits the growth, migration, and colony formation of breast cancer cells in vitro, and inhibits tumor growth in vivo. Primaquine induces damage to early endosomes and inhibits the nuclear translocation of EGFR. Primaquine inhibits the interaction of Stat3 and nEGFR and reduces the transcript and protein levels of c-Myc. Moreover, primaquine and chloroquine induce the apoptosis of breast cancer cells through c-Myc/Bcl-2 downregulation, induce early endosome damage and reduce nEGFR levels, and induce apoptosis in breast cancer through nEGFR/Stat3-dependent c-Myc downregulation. Our study of primaquine and chloroquine provides a rationale for targeting EGFR signaling components in the treatment of breast cancer.

Triple-negative breast cancer (TNBC) is highly aggressive and lacks targeted therapies. This study investigated the anti-cancer mechanisms of sinapaldehyde (SNAH). The biological effects of SNAH were evaluated in vitro using MDA-MB-231 TNBC cells. Cellular responses, including autophagy, mitochondrial function, apoptosis, cell-cycle progression, migration, and colony formation were investigated. In silico studies explored associated regulatory networks and binding targets. Sinapaldehyde (SNAH) treatment was associated with mitochondrial dysfunction, characterized by alterations in mitochondrial structural and functional markers, increased reactive oxygen species(ROS) production, and loss of mitochondrial membrane potential. SNAH treatment also altered the expression of PINK1 and Parkin and modulated autophagy-associated markers, including LC3B, p62, LAMP1, Beclin-1, and ATG proteins. Time-dependent changes in autophagy- and apoptosis-associated markers were accompanied by increased Annexin V-positive cells and activation of cleaved caspase-9 and caspase-3. SNAH also altered FTH1 and NCOA4 expression, suggesting modulation of ferritinophagy-associated processes, and inhibited migration and colony formation while inducing G2/M cell-cycle arrest. In silico analyses identified potential breast cancer-related molecular targets and signaling pathways associated with SNAH. SNAH induces mitochondrial dysfunction and is associated with alterations in autophagy/mitophagy-associated signaling and activation of apoptosis in MDA-MB-231 TNBC cells. These findings provide insight into the cellular responses to SNAH treatment, while further functional studies are required to establish changes in mitophagic and ferritinophagic flux and the causal relationship between autophagy and apoptosis.

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.