Synchronous detection of miRNAs, their targets and downstream proteins in transferred FFPE sections: applications in clinical and basic research.

After discovering new miRNAs, it is often difficult to determine their targets and effects on downstream protein expression. In situ hybridization (ISH) and immunohistochemistry (IHC) are two commonly used methods for clinical diagnosis and basic research. We used an optimized technique that simultaneously detects miRNAs, their binding targets and corresponding proteins on transferred serial formalin fixed paraffin embedded (FFPE) sections from patients. Combined with bioinformatics, this method was used to validate the reciprocal expression of specific miRNAs and targets that were detected by ISH, as well as the expression of downstream proteins that were detected by IHC. A complete analysis was performed using a limited number of transferred serial FFPE sections that had been stored for 1-4 years at room temperature. Some sections had even been previously stained with H&E. We identified a miRNA that regulates epithelial ovarian cancer, along with its candidate target and related downstream protein. These findings were directly validated using sub-cellular components obtained from the same patient sample. In addition, the expression of Nephrin (a podocyte marker) and Stmn1 (a recently identified marker related to glomerular development) were confirmed in transferred FFPE sections of mouse kidney. This procedure may be adapted for clinical diagnosis and basic research, providing a qualitative and efficient method to dissect the detailed spatial expression patterns of miRNA pathways in FFPE tissue, especially in cases where only a small biopsy sample can be obtained.

[Effect of cardiotrophin-1 on cardiac transcription factor GATA4 expression in rat cardiomyocytes].

OBJECTIVE: To investigate the effect of cardiotrophin-1 (CT-1) on the GATA4 expression and related signaling pathways (JAK-STAT3, ERK1/2 and PI3-K) in rat cardiomyocytes. METHODS: Using semi-quantitative RT-PCR and EMSA, we measured the dose and time dependent effects of CT-1 on GATA4 mRNA and binding activity in cultured rat cardiomyocytes. Parthenolide (a STAT inhibitor), U-0126 (an ERK inhibitor) and LY-294002 (a PI3-K inhibitor) alone or in combination were added to the culture medium to assess the role of above signaling pathways in CT-1 mediated effects. RESULTS: GATA4 mRNA expression significantly increased at 3 h post 0.1 nmol/L CT-1 exposure, peaked at 6 h and remained high till 24 h post exposure. The GATA4 binding activity began to increase at 10 min and peaked at 60 min and returned to baseline level 180 min. Six hours post CT-1 (0.01 nmol/L, 0.1 nmol/L, 1 nmol/L) exposure, the GATA4 mRNA expression increased in a dose-dependent manner. The GATA4 binding activity peaked with 0.1 nmol/L CT-1 and higher dose did not further increase the binding activity. U-0126 increased the GATA4 mRNA expression and enhanced the GATA4 binding activity and these effects could be partially attenuated with addition of Parthenolide. Parthenolide also prevented the increase of GATA4 mRNA and binding activity induced by CT-1. LY-294002 had no effects GATA4 mRNA and binding activity. CONCLUSION: CT-1 increases the GATA4 mRNA expression and binding activity in rat cardiomyocytes via STAT3/ERK1/2 pathways and these effects are independent of PI3-K pathway.