Disruption of HSPA8-GEMIN5 interaction suppresses colorectal cancer by impaired splicing-translation coupling-mediated proteostasis imbalance.

BACKGROUND

Colorectal cancer (CRC) is one of the most prevalent malignant tumors globally, and there is an urgent need for effective treatment strategies. The natural compound Deoxyshikonin (DSHK) has shown promising anti-tumor potential. However, the anti-CRC effects of DSHK and its molecular target remain unclear.

METHODS

The anti-CRC efficacy of DSHK was evaluated using human CRC cell lines, patient-derived organoids (PDOs), cell line-derived xenograft (CDX), and patient-derived organoid xenograft (PDOX) models. Target identification involved chemical proteomics, CETSA, SPR, and molecular dynamics simulations. Protein interactions were probed using SPIDER proximity labeling, Co-IP, GST pull-down, and confocal microscopy. The spatial distribution of interacting proteins was examined through high-density tissue microarrays, and functional pathways were explored via whole-transcriptome sequencing, rMATS, and ultrastructural imaging.

RESULTS

DSHK demonstrated potent antitumor efficacy in preclinical models of CRC. HSPA8 was identified as the direct molecular target of DSHK. Moreover, the anti-CRC effect of DSHK depended on HSPA8. Additionally, GEMIN5 was identified as a novel functional interactor of HSPA8 in CRC pathogenesis. The expression levels and co-localization intensity of HSPA8 and GEMIN5 were significantly higher in CRC tissues compared to adjacent normal tissues. Moreover, DSHK destabilized the oncogenic HSPA8-GEMIN5 complex, thereby triggering aberrant splicing of ribosomal protein-coding genes mediated by GEMIN5, thereby impeding functional ribosome biogenesis. Concomitantly, DSHK impaired HSPA8-mediated initiation factors interaction and destabilized the eIF4F complex, resulting in dysfunctional translation initiation.

CONCLUSIONS

DSHK targeted the HSPA8-GEMIN5 interaction interface to impair ribosome biogenesis and dysregulating translation initiation to suppress protein synthesis. This study established the newly identified HSPA8-GEMIN5 complex as a molecular hub mediating “splicing-translation coupling” in CRC and provided a novel “dual-pathway intervention targeting splicing and translation” strategy inducing proteostasis imbalance for CRC therapy.