Edible plant-derived nanovesicles have been explored as effective materials for preventing colorectal cancer (CRC) incidence, dependent on gene status, as a K-Ras-activating mutation via the macropinocytosis pathway. Approximately 70% of CRC harbors the p53 mutation, which is strongly associated with a poor prognosis for CRC. However, it has not been revealed whether p53 inactivation activates the macropinocytosis pathway or not. In this study, we investigated parental cells, wild-type or null for p53 treated with Citrus limon L.-derived nanovesicles, as potential materials for CRC prevention. Using ultracentrifugation, we obtained C. limon L.-derived nanovesicles, the diameters of which were approximately 100 nm, similar to that of the exosomes derived from mammalian cells. C. limon L.-derived nanovesicles showed inhibitory effects on cell growth in not p53-wild, but also in p53-inactivated CRC cells. Furthermore, we revealed that the macropinocytosis pathway is activated by p53 inactivation and C. limon L.-derived nanovesicles were up taken via the macropinocytosis pathway. Notably, although C. limon L.-derived nanovesicles contained citrate, the inhibitory effects of citrate were not dependent on the p53 status. We thus provide a novel mechanism for the growth inhibition of C. limon L.-derived nanovesicles via macropinocytosis and expect to develop a functional food product containing them for preventing p53-inactivation CRC incidence.

Resveratrol has various attractive bioactivities, such as prevention of cancer, neurodegenerative disorders, and obesity-related diseases. Therefore, identifying its direct binding proteins is expected to discover druggable targets. Sirtuin 1 and phosphodiesterases have so far been found as the direct molecular targets of resveratrol. We herein identified 11 novel resveratrol-binding proteins, including the DEAD (Asp-Glu-Ala-Asp) box helicase 5 (DDX5, also known as p68), using resveratrol-immobilized beads. Treatment with resveratrol induced degradation of DDX5 in prostate cancer cells. Depletion of DDX5 caused apoptosis by inhibiting mammalian target of rapamycin complex 1 (mTORC1) signaling. Moreover, knockdown of DDX5 attenuated the inhibitory activities of resveratrol against mTORC1 signaling and cancer cell growth. These data show that resveratrol directly targets DDX5 and induces cancer cell death by inhibiting the mTORC1 pathway.

The X-linked inhibitor of apoptosis (XIAP) confers the resistance of various types of cancer to standard chemotherapeutic agents such as anthracycline and taxane. In breast cancer, XIAP is known to be overexpressed. However, the mechanisms underlying the overexpression of XIAP remain currently unclear. In order to elucidate the mechanisms responsible for the overexpression of the XIAP protein in breast cancer, we attempted to clarify the mechanisms by which the natural compound curcumin downregulates XIAP in breast cancer cells. In that process, we identified the ribosomal protein S3 (RPS3) as a curcumin‑binding protein using curcumin-fixed magnetic FG beads. The knockdown of RPS3 inhibited cell growth and induced apoptosis as well as the downregulation of XIAP in breast cancer cells. Although RPS3 is known to directly bind to and activate the nuclear factor-κB (NF-κB), which induces several anti-apoptotic genes such as XIAP, the knockdown of RPS3 unexpectedly reduced the levels of the XIAP protein, but not the mRNA level of XIAP and the transcription factor NF-κB activity. These results reveal that RPS3 upregulates XIAP independently of the NF-κB pathway in human breast cancer cells.

KRAS mutation is frequently seen in a subtype of ovarian cancer categorized as type 1. The KRAS‐MAPK pathway, which is closely involved in type 1 cancer progression, is under the regulation of receptor tyrosine kinases (RTKs). AXL, one of the RTKs, has been reported to be overexpressed in ovarian cancer and contributes to the poor prognosis. However, there is no useful target‐based agent against such gene profiles. We examined the combined effect of the dual RAF/MEK inhibitor CH5126766 and AXL inhibitor R428 on the growth of ovarian cancer HEY‐T30 and OVCAR‐5 cell lines, both of which bear KRAS mutation and express AXL at a high level, using the WST‐8 assay and the colony formation assay. The synergistic effect of the combination was evaluated by the combination index. The apoptotic cells were analyzed by flow cytometry. The expression of apoptotic proteins and the phosphorylation of MAPK and AKT pathway proteins were investigated by western blotting. We found that CH5126766 and R428 suppressed the phosphorylation of ERK and AKT, respectively, and their combination synergistically inhibited the growth of both cell lines with enhancement of apoptosis accompanied by the Bim upregulation. Combined treatment with CH5126766 and R428 is expected as the novel therapeutic option for KRAS‐mutated ovarian cancer with high expression of AXL.