Distinct microRNA Expression Profiles in Mouse Renal Cortical Tissue after (177)Lu-octreotate Administration

AIM: The aim of this study was to investigate the variation of the miRNA expression levels in normal renal cortical tissue after (177)Lu-octreotate administration, a radiopharmaceutical used for treatment of neuroendocrine cancers. METHODS: Female BALB/c nude mice were i.v. injected with 1.3, 3.6, 14, 45, or 140 MBq (177)Lu-octreotate, while control animals received saline. The animals were killed at 24 h after injection and total RNA, including miRNA, was extracted from the renal cortical tissue and hybridized to the Mouse miRNA Oligo chip 4plex to identify differentially regulated miRNAs between exposed and control samples. RESULTS: In total, 57 specific miRNAs were differentially regulated in the exposed renal cortical tissues with 1, 29, 21, 27, and 31 miRNAs identified per dose-level (0.13, 0.34, 1.3, 4.3, and 13 Gy, respectively). No miRNAs were commonly regulated at all dose levels. miR-194, miR-107, miR-3090, and miR-3077 were commonly regulated at 0.34, 1.3, 4.3, and 13 Gy. Strong effects on cellular mechanisms ranging from immune response to p53 signaling and cancer-related pathways were observed at the highest absorbed dose. Thirty-nine of the 57 differentially regulated miRNAs identified in the present study have previously been associated with response to ionizing radiation, indicating common radiation responsive pathways. CONCLUSION: In conclusion, the (177)Lu-octreotate associated miRNA signatures were generally dose-specific, thereby illustrating transcriptional regulation of radiation responsive miRNAs. Taken together, these results imply the importance of miRNAs in early immunological responses in the kidneys following (177)Lu-octreotate administration.