Functional characterization of the intronic noncoding RNA mapping to the PPP3CB locus and overexpressed in pancreatic tumor metastasis using apoptosis assays.

Abstract

It is known that ~90% of human genome is transcribed in RNAs with little or no protein-coding capacity. Some noncoding RNAs (ncRNA), such as rRNA, tRNA, have well established roles in cellular metabolism. Several recent works suggest a functional role to these ncRNAs as a modulator of gene expression, so they are unlikely to represent transcriptional "noise". Although there have been advances in ncRNA research, the functions of the majority of these molecules are still unknown. Several ncRNAs have been shown to be differentially expressed in cancer and it is possible that some will have important functional roles in tumor development. Their characterization may bring new insights to the field of cancer research. Pancreatic adenocarcinoma is considered one of the most aggressive cancers with a high mortality rate due to the lack of early diagnosis and limited response to available treatment. Since cancer development and progression are frequently accompanied by complex alteration in gene expression, there is great need to study the molecular mechanisms involved in malignant transformation of pancreatic cancer. An important feature of tumoral metastatic cell is the resistance to apoptosis. Although advances have been obtained in researches related to apoptosis and pancreatic cancer, studies involving regulation of long intronic noncoding RNAs are still inexistent. This work aims to analyze the function of a long ncRNA expressed in a genomic region encompassing an intron of PPP3CB gene and to evaluate the potential role of this noncoding transcript in the apoptosis process using a pancreatic cell lineage as model. This ncRNA was identified by our group as up-regulated in biopsies of metastatic pancreatic cancer compared to primary tumor samples. As metastatic pancreatic tumors present more resistance to apoptosis process, we hipotesized that the expression of the PPP3CB intronic ncRNA could be associated with apoptosis resistance. To test this hypothesis, we will use a pancreatic tumor cell lineage (Mia PaCa - 2) to overexpress the PPP3CB intronic ncRNA or to knock-down the endogenous transcript, to investigate the effects of manipulating the levels of this ncRNA on apoptosis and cell death.