Low Magnetic Field Exposure Alters Prostate Cancer Cell Properties

Abstract

Prostate cancer is the second most common neoplasia and fifth-leading cause of cancer death in men worldwide. Electromagnetic and magnetic fields have been classified as possible human carcinogens, but current understanding of molecular and cellular pathways involved is very limited. Effects due to extremely low magnetic/hypomagnetic fields (LMF) are furthermore poorly understood. Extracellular vesicles (EVs) are crucial mediators of cellular communication with multifaceted roles in cancer progression, including via transport and uptake of various protein and microRNA (miRNA) EV-cargoes. miRNAs regulate gene expression and are implicated in cancer-related processes such as proliferation, metastasis, and chemoresistance. This study investigated the effects of LMF exposure (20 nT) by magnetic shielding on the prostate cancer cell line PC3 compared to the prostate epithelial cell line PNT2 under short-term (4 h) conditions. We examined EV profiles following a 4 h LMF exposure alongside associated functional enrichment KEGG and GO pathways for the EV proteomes. The 4 h LMF exposure significantly reduced cellular EV release and modified PC3 EV cargoes to a more inflammatory and metastatic profile, with 16 Disease Pathways and 95 Human Phenotypes associated specifically with the LMF-treated PC3 EV proteomes. These included cancerous, metabolic, blood, skin, cardiac and skeletal Disease Pathways, as well as pain and developmental disorders. In the normal PNT2 cells, less EV protein cargo was observed following LMF exposure compared with cells not exposed to LMF, and fewer associated functional enrichment pathways were identified. This pointed to some differences in various cellular functions, ageing, defence responses, oxidative stress, and disease phenotypes, including respiratory, digestive, immune, and developmental pathways. Furthermore, we analysed alterations in matrix metalloproteinases (MMPs) and miRNAs linked to metastasis, as this is crucial in cancer aggressiveness. The 4 h LMF exposure caused a significant increase in MMP2 and MMP9, as well as in onco-miRs miR-155, miR-210, miR-21, but a significant reduction in tumour-suppressor miRs (miR-200c and miR-126) in the metastatic PC3 cells, compared with normal PNT2 cells. In addition, 4 h LMF exposure significantly induced cellular invasion of PC3 cells. Overall, our findings suggest that changes in magnetic field exposures modulate EV-mediated and miR-regulatory processes in PCa metastasis, providing a basis for exploring novel therapeutic strategies.