Acute high-dose irradiation of human primary ovarian cells reveals a shift in transcriptomics profile and impairment in cell-cell adhesion

Abstract

STUDY QUESTIONHow do human cortical (cPOCs) and medullary (mPOCs) primary ovarian cells respond to acute X-ray exposure? SUMMARY ANSWERAcute high-dose X-ray exposure causes a shift in cPOCs and mPOCs transcriptomic profiles and impairs significantly their cell-cell adhesion ability. WHAT IS KNOWN ALREADYRadiotherapy is a leading cancer treatment, due to its effectiveness in targeting malignant cells. However, it can also affect healthy cells, potentially causing organ dysfunction, among which ovaries. When targeted radiotherapy is not feasible, fertility preservation is recommended to avoid premature ovarian insufficiency. In addition, the effects of irradiation on ovarian somatic cells remain poorly understood. STUDY DESIGN, SIZE, DURATIONOvarian tissue was obtained from patients undergoing gender-affirming surgery at Karolinska University Hospital Huddinge, Sweden. The ovarian tissue was separated into cortex and medulla, then individually dissociated into single-cell suspensions using mechanical and enzymatic methods. Monolayer cultures from cPOCs and mPOCs were exposed to a single dose of 10 Gy X-ray irradiation or left unexposed as paired controls. Following irradiation, the cells were cultured at various time-points for further molecular and morphological evaluation. PARTICIPANTS/MATERIALS, SETTING, METHODSOvarian tissue from 8 patients (age 23-36 years) was used. Dissociated cPOCs and mPOCs were cultured to 80% confluence and irradiated with 10 Gy (1.33 Gy/min), with non-irradiated controls. Cellular ATP and mitochondrial activity were assessed, followed by immunofluorescence staining for canonical irradiation-induced effects in cells: DNA damage, apoptosis and cell cycle progression. Bulk RNA-sequencing was performed on controls and irradiated samples. Libraries were prepared using the Illumina Stranded mRNA Prep Ligation protocol and sequenced on Illumina NovaSeq6000 platform. Genes were considered to be differentially expressed under the cut-off of false discovery rate (FDR) < 0.05. Subsequently, affected biological pathway was predicted using all expressed genes ranked by log2 fold change again hallmark gene sets. To further investigate the potential upstream regulators, transcription factor enrichment analysis were performed based on DEGs. To assess changes at protein level, we mapped the proteomic profile using liquid chromatography-tandem mass spectrometry. Peptides were considered to be differentially expressed (DEPs) under the cut-off of p-value < 0.01. Finally, we measured the ability of cPOCs and mPOCs to form 3D aggregates after seeding irradiated and non-irradiated cells on Biosilk scaffolds. MAIN RESULTS AND THE ROLE OF CHANCEFollowing irradiation, ATP levels and mitochondrial activity in cPOCs and mPOCs were comparable to controls, indicating minimal irradiation impact on cell viability and proliferation. Immunofluorescence analysis confirmed the modulation of canonical pathways, such as DNA damage, apoptosis and cell cycle in both cPOCs and mPOCs. Transcriptomic analysis showed that cPOCs and mPOCs at 1 h post-irradiation clustered together with the related 1 h control. However, a shift in transcriptomic profile was observed after 4 h and even more after 24 h post-irradiation in both cPOCs and mPOCs. Gene set enrichment analysis (GSEA) indicated upregulation of the p53 pathway at 4 h and 24 h post-irradiation, alongside downregulation of MYC targets, E2F targets, the G2/M checkpoint and mTORC1 pathway. Gene pattern analysis showed irradiation-dependent trends related to extracellular matrix (ECM) organisation, p53-mediated apoptotic mechanisms and chromosome segregation during the 24 h period following irradiation. Additionally, transcription factor enrichment analysis based on DEGs suggested p53 and MYC as potential upstream regulators. On a proteomic level, DEPs associated with ECM organisation and cytoskeleton formation were detected at 4 and 24 h post-irradiation. Finally, X-ray exposure hindered the cell-cell adhesion ability of both cPOCs and mPOCs, leading to impaired formation of Silk-Ovarioids. LARGE SCALE DATAThe RNA sequencing count matrix is deposited in Gene Expression Omnibus (GEO) with accession number GSE291604. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD061796. The code used for the analysis can be found at https://github.com/tialiv/X-Ovary. LIMITATIONS, REASONS FOR CAUTIONThe ovarian tissue was obtained from gender-affirming surgery patients who received androgen treatment before removal. Even though unlikely, this hormonal treatment might influence ovarian environment and alter cellular response to irradiation. Additionally, in this study the impact of X-ray exposure was assessed on a monolayer cell model, thus limiting the extrapolation power of our results to ovary in vivo. Lastly, the impact of irradiation was focused on the somatic cell populations that are essential for ovarian function. Further studies are needed to investigate the effects of X-ray exposure on ovarian follicles and their function. WIDER IMPLICATIONS OF THE FINDINGSUnderstanding the roles of MYC, p53 and cell adhesion factors in response to irradiation could guide the development of future ovarian protective strategies. These findings lay the foundation for further studies on ovarian tissue protection and fertility preservation in cancer patients. STUDY FUNDING/COMPETING INTEREST(S)This work was funded by the European Unions HORIZON 2020 research and innovation programme (MATER) under the Marie Skodowska-Curie Actions (grant agreement No: 813707), the Estonian Research Council (grants PRG1076 and PSG608), the Orion Research Foundation sr personal grant, the Research grant from the Center for Innovative Medicine (CIMED) and the Karolinska Institutet Consolidator Grant.