PRDM1-driven SLC30A9 overexpression contributes to the malignant phenotype of cervical cancer cells via promoting mitochondrial hyperfunction

Abstract

Mitochondrial hyperfunction is important for cervical cancer progression. Solute carrier family 30 member 9 (SLC30A9) is a member of the solute carrier family 30, specifically a zinc transporter that plays a critical role in mitochondrial zinc homeostasis and maintaining mitochondrial function. We investigated the expression, function, and underlying mechanisms of SLC30A9 in the context of cervical cancer. Single-cell RNA sequencing analysis revealed a marked overexpression of SLC30A9 within the malignant epithelial cell population of cervical squamous cell carcinoma. This elevated SLC30A9 expression was further corroborated in clinical specimens from local patients and across various established and primary cervical cancer cells. SLC30A9 shRNA or knockout (via CRISPR/Cas9 method) significantly impeded the viability, proliferation, cell cycle progression and migration, and triggered apoptosis in cervical cancer cells. SLC30A9 depletion disrupted mitochondrial function, inhibiting mitochondrial respiration, mitochondrial membrane potential, mitochondrial complex I activity, and ATP production, also caused mitochondrial Zn ²⁺ accumulation, reactive oxygen species (ROS) production and oxidative injury. Conversely, overexpression of SLC30A9 in cervical cancer cells demonstrated enhanced mitochondrial complex I activity, increased ATP production, and augmented cellular proliferation and migration. Bioinformatic analysis, coupled with functional validation, identified PRDM1 (PR Domain Containing 1) as a key transcription factor regulating SLC30A9 expression. Silencing or knockout of PRDM1 resulted in a significant reduction in SLC30A9 promoter activity, as well as decreased SLC30A9 mRNA and protein levels in primary cervical cancer cells. Chromatin immunoprecipitation (ChIP) assays confirmed increased PRDM1 binding to the SLC30A9 promoter region in cervical cancer tissues. In vivo studies showed that SLC30A9 knockdown led to a remarkable decrease in the growth of xenografts formed by primary cervical cancer cells. These SLC30A9-silenced xenografts exhibited mitochondrial dysfunction, proliferation inhibition and apoptosis induction. These findings collectively suggest that PRDM1-driven SLC30A9 overexpression significantly contributes to the malignant phenotype of cervical cancer, possibly through promoting mitochondrial hyperfunction.