Are Changes in MicroRNAs Expression A Relevant Biomarker for Urinary Bladder Cancer Prognosis?

Constantinescu. Are Changes in MicroRNAs Expression A Relevant Biomarker for Urinary Bladder Cancer Prognosis?. Abstract Background: Bladder cancer is one of the dominating causes of death worldwide. The identification of microRNA functions in carcinogenesis has given a new direction for the development of novel biomarkers. Aims: We have investigated seven microRNAs (miR-124, miR-126, miR-139, miR-145-3p, miR-145-5p, miR-152, miR-182) in order to define their clinical relevance in diagnosis and prognosis of bladder cancer patients. We have analyzed expression levels of these microRNAs in tumor samples versus normal tissues, as well as correlation between their expression levels and staging and lymph node metastasis. Methods: Expression levels of selected microRNAs were assessed by TaqMan RT-PCR assay. The data obtained were revealed using GraphPad Prism 6.01 software which enabled the statistical analysis of the correlation between the miRNA expressions and tumor stage. Results: We have found a consistent epigenetic signature in tumor samples including significant downregulation of miR-126, miR-139, miR-145-5p, miR-145-3p, miR-152, as well as upregulation of miR-182 compared to normal tissues. The expressions of miR126, miR-139 and miR-152 were significantly downregulated in patients with T3N0 stages compared to patients with T3N positive stages. Our preliminary data show that selected miRNAs are clinically relevant for monitoring the urinary bladder cancer patients.

This process is in accordance with tumor development [7]. Particular epigenetic regulation of mRNAs corresponding to TSG or OG may characterize differently miRNAs as tumorigenic (having OG role), or tumor suppressive (having TSG role). Post transcriptional epigenetic control of OG or TSG mRNA translation may be positive in the context of miRNA under-expression and negative in the context of miRNA overexpression. Therefore, a miRNA species that negatively regulate an OG mRNA became a TS-miRNA with tumor suppressive role. By contrast, its under-expression is able to positively regulate an OG mRNA translation defining its OG or tumorigenic role. In the same way the overexpression of miRNA species that negatively regulating a TSG mRNA has tumorigenic or OG role, while its under-expression towards the same TSG mRNA may turn in to opposite tumor suppressive or TSG role.7 In some cases, the same microRNA may have dual activities acting either as an OG or TSG in a tissue-specific manner, in different stages of the tumor progression [8]. Previously, we have reported our results regarding the expression profile of certain microRNAs (miR-145-3p, miR-145-5p, miR-152 and miR-182) in Romanian patients with urinary bladder cancer [9].
This work uses these preliminary results and investigates the clinical relevance of additional miRNAs species (miR-124, miR-126 and miR-139) in our patients. The present approach aims to figure the possibility of defining an epigenetic molecular diagnosis algorithm. Moreover, the new results establish the tumorigenic role (as tumor suppressor gene or oncogene) for each microRNA.
Detailed discussions of these aspects compared with statistical analysis values are reported as the final criteria for selection of relevant microRNAs. The extended microRNAs expression markers could provide more relevant information. We are interested to seek for the relevance of the selected miRNAs in delimitating the stages during bladder cancer progression related to TNM (Tumor, Node,

Metastasis) classification. Modulation of microRNA expression
is increasingly considered to be an important mechanism by which tumor suppressor proteins and oncoproteins exert some of their effects with important results regarding the stages of the carcinogenesis. This work considered such concepts by a particular statistical tool that enabled a comparison between the expressions of miRNA species during the various carcinogenesis stages.

Patients
In this study we have included ninety patients with urinary Also, all samples were processed for pathological examination by standard diagnostic procedure, according to TNM classification.
Informed written consent was obtained from all patients, and the research protocol was approved by the Fundeni Clinical Institute Ethical Committee.  c)

MicroRNA Expressions Profile Between Tumor Samples and Normal Tissue Samples
The expression levels of miR-145-3p, miR-145-5p and miR-152 remained significantly under-expressed (P<0.001 in tumor bladder tissues compared to normal bladder tissues [9] d) miR-182 was significantly upregulated in bladder cancer tissues versus normal tissues [9].

MicroRNA Expression Analysis According to Cancer Stage
The patients were divided by their cancer stage as follows: I, II,    (Figure 3).    level expression due to miR-126 under-expression is involved in increasing invasive potential of bladder cancer cells [27].

MicroRNA Expression Analysis According to Lymph Node Metastases
miR-126 has important regulatory function in PI3K/Akt pathway transduction, which is thought to play a major role in bladder carcinogenesis [28]. Inhibition of PIK3R2 expression and the PI3K /Akt signaling pathway by miR126 suggests that it can negatively regulate targeted gene and inhibit the signaling pathway PIK3R2/PI3K/Akt [29]. miR-139 is located on chromosome 11q13.4 and has anti-oncogenic and anti-metastatic activity. Deregulation    prediction. Also, they may be efficiently used for the innovative molecular treatment of tumor tissues by injecting precise synthetic oligonucleotides able to modify the in vivo miRNA expression that could have a particular tumorigenic activity.

Declaration of Conflicting Interests
The authors declare that there are no conflicts of interest.