Effect of transforming RNA on the synthesis of a protein with a secretory signal sequence in vitro

Down-regulation of small nuclear RNA (snRNA) RNU5E-1 in hepatocellular carcinoma presents with vital clinical significance

Background

For lack of accurate diagnosis and ideal prognosis assessment, hepatocellular carcinoma (HCC) has become the fourth cancers-related death malignant diseases. Small nuclear RNAs (snRNAs) have been investigated as a new class of regulators associated with pathogenesis and clinical evaluation of tumors such as HCC. As for RNU5E-1, one newly identified snRNA, may have similar functions. However, the relationship between RNU5E-1 expression and HCC tumorigenesis remains unclear.

Methods

The relative RNU5E-1 expression was measured in several HCC cell lines and HCC tissues of 100 patients using quantitative real-time PCR. All patients were grouped according to individual RNU5E-1 expression. Then, the potential association between RNU5E-1 expression in HCC clinical characteristics and prognostic information of patients was evaluated.

Results

Compared to human normal hepatocyte cell line QSG-7701, the RNU5E-1 expression in HCC cell lines (fold change: SK-HEP-1, 0.417; Hep 3B, 0.313; Huh-7, 0.189) were significantly down-regulated (P<0.05). Similarly, its expression levels were remarkably lower in HCC tissue than that in corresponding adjacent liver tissues (average fold change: 0.322, P=0.002). Besides, the expression level of RNU5E-1 was remarkably related to tumor size, vessel carcinoma embolus, differentiation level, TNM stages and tumor recurrence rate as well as long-term survival in HCC patients (P<0.05). Moreover, in Kaplan-Meier and Cox regression analysis, RNU5E-1 expression was remarkably correlated to postoperative tumor-free as well as long-term survival in HCC patients as independent factors (P<0.05).

Conclusions

The research revealed that RNU5E-1 was down-regulated in HCC and it could be one of indicators for diagnosis and prognostic prediction of HCC patients.

Inhibition of gap junctional intercellular communication in rat liver epithelial cells with transforming RNA

Previous studies indicated that transforming RNA, derived from the 3' half of the U5 small nuclear RNA first stem structure, suppressed the secretory protein translation in vitro. Gap junctions facilitate homeostatic control of cell growth and differentiation and their dysfunction has been correlated with carcinogenesis. Here, we reported that transforming RNA directly suppressed the gap junction protein, connexin 43, translation and thereby inhibited functional gap junction function in rat epithelial cells. Together with previous data, this implies that altered expression of transforming RNA itself is a potential mechanism in inhibiting gap junction function during carcinogenesis.