Background
Space exploration exposes humans to unique environments, causing molecular and cellular changes. Microgravity affects vital biological processes, including cancer development. Examining cancer cells in microgravity can yield insights and improve drug resistance. Studies on thyroid cancer cells have been conducted, but limited gene expression research is available. This study aims to compare gene expression and migration and invasion abilities in thyroid-related cell lines under normal and microgravity conditions.
Method and Materials
We cultured five distinct thyroid cell lines (Nthy-ori 3-1, TPC-1, BAPAP, SNU-790, and SNU-80) under both normal gravity and simulated microgravity conditions using the clinostat equipment. A clinostat is a device which uses rotation to negate the effects of gravitational pull on cell culture. After 5 days of culture, we used cDNA microarrays to assess gene expression in all five cancer cell lines under both gravity conditions. We identified differentially expressed genes (DEGs) by comparing microgravity to normal gravity using Transcriptome Analysis Console version 4.0. To analyze the functional aspects, we conducted KEGG pathway analysis, Gene Ontology enrichment analysis, and Gene Set Enrichment Analysis (GSEA). Additionally, to analyze the effect of microgravity on aggressiveness of cultured cells, we performed Transwell migration and invasion assays for all five cell lines.
Results
Every cell exhibited larger cell morphology, and there were no consistent results in cell counts among different cell types. After 5 days of culture under microgravity, the number of DEGs was 636 for SNU-790, 205 for BCPAP, 54 for TPC-1, 48 for Nthy-ori 3-1, and 29 for SNU-80. Gene ontology enrichment analysis revealed that SNU-790 and TPC-1 cells exhibited enrichment in cellular components related to nucleosomes, while SNU-80, Nthy-ori 3-1, and BCPAP cells showed responses related to the extracellular space. GSEA revealed that gene sets related to pathways in cancer were enriched in a microgravity environment. Furthermore, Transwell migration and invasion assays demonstrated an increase in cell migration and invasion for specific cell lines in microgravity conditions.
Conclusions
This study discovered an upregulation of genes associated with cancer pathways and revealed an augmentation in the migration and invasion capabilities of thyroid cells. Additionally, the research identified differentially expressed genes related to the nucleosome and extracellular matrix under microgravity conditions. These findings contribute to our understanding of the changes in thyroid-related cells exposed to microgravity and may offer insights into the mechanisms of cancer. Furthermore, this research holds significance in acquiring crucial information related to human health in space. Subsequent studies should explore other organs besides the thyroid, and similar investigations should be conducted under actual microgravity conditions.