Cisplatin-induced disruption of mitochondrial divisome leads to enhanced cisplatin resistance in cholangiocarcinoma

Abstract

Background & aims: Cisplatin (CDDP)-based chemotherapy is the primary treatment for advanced cholangiocarcinoma (CCA), but its clinical efficacy is limited. The mitochondrial divisome (MD) is crucial for regulating mitochondrial division, but its roles in CDDP resistance remain unclear.

Methods: Alternations of mitochondrial morphology, expression levels and localization of MD components in CCA under CDDP treatment were evaluated using fluorescence labeling and mitochondrial isolation at cellular and organoid levels. Gene editing and other strategies demonstrated the link between mitochondrial hyperfusion and CDDP resistance. RNA sequencing revealed altered molecular landscapes in CCA cells following CDDP exposure. Mass spectrometry and immunoprecipitation were mainly adopted to explore the mechanisms of degradation of the actin-binding protein INF2 (inverted formin-2). Endoplasmic reticulum (ER)-phagy was characterized using stable transfection of ssRFP-GFP-KDEL. The clinical significance of INF2 was assessed by analyzing tumor samples of 438 patients with CCA using tissue microarray. Combination therapy efficacy was validated in cell line- and patient-derived xenograft mouse models.

Results: CDDP dramatically damaged various MD components, leading to increased F-actin peripheral polymerization, decreased ER colocalization with mitochondria, and INF2 degradation. These events promoted adaptive mitochondrial hyperfusion, contributing to CDDP resistance in CCA. INF2 plays a pivotal role in MD-associated CDDP resistance, with its degradation primarily occurring through the proteasome pathway and SEC62-mediated ER-phagy. Inhibiting these pathways increased CDDP sensitivity in CCA, whereas targeting other MD components failed to confer such an effect.

Conclusions: We propose a novel feasible treatment strategy to reverse CDDP resistance in CCA by targeting mitochondrial morphology. Our study highlights the importance of monitoring dynamic changes at the protein and organelle levels during anticancer treatment, providing robust evidence for functional precision oncology.

Impact and implications: This study identifies that high INF2 expression at baseline is associated with poor prognosis in patients with cholangiocarcinoma. Moreover, cisplatin-induced INF2 degradation via proteasomal and SEC62-mediated ER-phagy is identified as a key driver of mitochondrial hyperfusion and chemoresistance in cholangiocarcinoma. These data establish mitochondrial morphology as a novel therapeutic target to overcome chemotherapy resistance. Furthermore, this study emphasizes the need to focus on dynamic changes in tumor proteins or organelle functions during treatment (functional precise oncology), rather than limiting analysis to static tumor states. Given that inhibition of oncogenes may lead to potential resistance mechanisms, comprehensive preclinical evaluations are essential before clinical application.

Keywords: Cisplatin resistance; ER-phagy; INF2; SEC62; cholangiocarcinoma; mitochondrial divisome.