Elevated expression patterns of P-element Induced Wimpy Testis (PIWI) transcripts are potential candidate markers for Hepatocellular Carcinoma.

BACKGROUND: P-Element-induced wimpy testis (PIWI) proteins, when in combination with PIWI-interacting RNA (piRNA), are engaged in the epigenetic regulation of gene expression in germline cells. Different types of tumour cells have been found to exhibit abnormal expression of piRNA, PIWIL-mRNAs, and proteins. We aimed to determine the mRNA expression profiles of PIWIL1, PIWIL2, PIWIL3, & PIWIL4, in hepatocellular carcinoma patients, and to associate their expression patterns with clinicopathological features. METHODS: The expression patterns of PIWIL1, PIWIL2, PIWIL3, PIWIL4 mRNA, was assessed via real-time quantitative polymerase chain reaction (RT-QPCR), on tissue and serum samples from HCC patients, their impact for diagnosis was evaluated by ROC curves, prognostic utility was determined, and In Silico analysis was conducted for predicted variant detection, association with HCC microRNAs and Network Analysis. RESULTS: Expression levels were significantly higher in both HCC tissue and serum samples than in their respective controls (p< 0.001). Additionally, the diagnostic performance was assessed, Risk determination was found to be statistically significant. CONCLUSION: PIWIL mRNAs are overexpressed in HCC tissue and serum samples, the expression patterns could be valuable molecular markers for HCC, due to their association with age, tumour grade and pattern. To the best of our knowledge, our study is the first to report the expression levels of all PIWIL mRNA and to suggest their remarkable values as diagnostic and prognostic biomarkers, in addition to their correlation to HCC development. Additionally, a therapeutic opportunity might be also suggested through in silico miRNA prediction for HCC and PIWIL genes through DDX4 and miR-124-3p.

Isolation and Processing of Bovine Oocytes for Small RNA Sequencing.

In modern biomedical research, mice have been the mammalian model system of choice to investigate molecular pathways for potential future medical applications. Over the last years, it has become clear that female mice employ an exceptional piRNA pathway-independent mechanism to neutralize transposon activity in the ovary. In other model organisms studied to date, the piRNA pathway is indispensable for efficient targeting of transposable elements and fertility in both males and females. Moreover, recent studies have demonstrated that in other mammals, including humans, the piRNA pathway is highly active in the female germline as well, indicating that the situation in the mouse female germline is anomalous. For this reason, novel models to study piRNA pathways in female mammalian germlines are currently emerging, including Bos taurus. Here we describe a protocol for isolation and downstream processing of female bovine tissues in order to perform downstream applications including piRNA sequencing.

A Novel PiRNA Enhances CA19-9 Sensitivity for Pancreatic Cancer Identification by Liquid Biopsy.

Pancreatic cancer is one of the deadliest tumours worldwide, and its poor prognosis is due to an inability to detect the disease at the early stages, thereby creating an urgent need to develop non-invasive biomarkers. P-element-induced wimpy testis (PIWI) proteins work together with piwi-interacting RNAs (piRNAs) to perform epigenetic regulation and as such hold great potential as biomarkers for pancreatic cancer. PIWIL2 and PIWIL4 are associated with better prognosis, while PIWIL1 and PIWIL3 involvement appears to be associated with carcinogenesis. We aimed to discover PIWIL3- and PIWIL4-modulated piRNAs and determine their potential mechanisms in pancreatic cancer and the clinical implications. PIWIL3 or PIWIL4 was downregulated in pancreatic cancer-derived cell lines or in a non-tumour cell line. Differentially expressed piRNAs were analysed by next generation sequencing of small RNA. Nine fresh-frozen samples from solid human pancreases (three healthy pancreases, three intraductal papillary mucinous neoplasms, and three early-stage pancreatic cancers) were included in the sequencing analysis. Two piRNAs associated with PIWIL3 (piR-168112 and piR-162725) were identified in the neoplastic cells; in untransformed samples, we identified one piRNA associated with PIWIL4 (pir-366845). After validation in pancreatic cancer-derived cell lines and one untransformed pancreatic cell line, these piRNAs were evaluated in plasma samples from healthy donors (n = 27) or patients with pancreatic cancer (n = 45). Interestingly, piR-162725 expression identified pancreatic cancer patients versus healthy donors in liquid biopsies. Moreover, the potential of the serum carbohydrate antigen 19-9 (CA19-9) biomarker to identify pancreatic cancer patients was greatly enhanced when combined with piR-162725 detection. The enhanced diagnostic potential for the early detection of pancreatic cancer in liquid biopsies of these new small non-coding RNAs will likely improve the prognosis and management of this deadly cancer.

The expression and the role of PIWI like RNA-mediated gene silencing 3 (PIWIL3) in lung cell line.

BACKGROUND: To determine the expression and role of PIWI-like RNA-mediated gene silencing 3 (PIWIL3) in human lung cancer. METHODS: Immunohistochemistry was performed to measure the expression of PIWIL3 in 30 of pairs lung cancer and corresponding paracancer tissues. Quantitative PCR (qPCR) was conducted to analyze the expression of PIWIL3 in four breast cancer cell lines. siRNA was used to silence PIWIL3 in the lung cancer cells (A549). Methylthiazoletetrazolium (MTT) proliferation assay and colony formation assay were conducted to detect the growth of A549 cells. Fluorescence-activated cell sorting (FACS) was performed to measure the apoptosis of A549 cells. Transwell migration assay and wound scratch healing assay were used to analyze the migration and invasion ability of A549 cells. SPSS 20.0 was used to analyze the data. RESULTS: The expression of PIWIL3 protein was higher in tumor tissues than that in paracancer tissues. In addition, PIWIL3 mRNA was highly expressed in all four lung cancer cell lines. Furthermore, RPS15A knockdown significantly suppressed cell proliferation (P<0.01), induced apoptosis (P<0.01) and inhibited metastasis (P<0.01) of A549 cells. CONCLUSIONS: PIWIL3 was highly expressed in lung cancer tissues and could promote the progression of lung cancer.

The Clinical Significance of PIWIL3 and PIWIL4 Expression in Pancreatic Cancer.

P-element-induced wimpy testis (PIWI) proteins have been described in several cancers. PIWIL1 and PIWIL2 have been recently evaluated in pancreatic cancer, and elevated expression of PIWIL2 conferred longer survival to patients. However, PIWIL3's and PIWIL4's role in carcinogenesis is rather controversial, and their clinical implication in pancreatic cancer has not yet been investigated. In the present study, we evaluated PIWIL1, PIWIL2, PIWIL3 and PIWIL4 expression in pancreatic cancer-derived cell lines and in one non-tumor cell line as healthy control. Here, we show a differential expression in tumor and non-tumor cell lines of PIWIL3 and PIWIL4. Subsequently, functional experiments with PIWIL3 and/or PIWIL4 knockdown revealed a decrease in the motility ratio of tumor and non-tumor cell lines through downregulation of mesenchymal factors in pro of epithelial factors. We also observed that PIWIL3 and/or PIWIL4 silencing impaired undifferentiated phenotype and enhanced drug toxicity in both tumor- and non-tumor-derived cell lines. Finally, PIWIL3 and PIWIL4 evaluation in human pancreatic cancer samples showed that patients with low levels of PIWIL4 protein expression presented poor prognosis. Therefore, PIWIL3 and PIWIL4 proteins may play crucial roles to keep pancreatic cell homeostasis not only in tumors but also in healthy tissues.

Expression of PIWIL3 in primary and metastatic melanoma.

PURPOSE: The PIWI-interacting RNA machinery in malignant melanoma (MM) has not been sufficiently studied. We aimed to investigate the PIWIL3 expression profiles in primary melanomas and metastases of MM including a correlation with clinical data. METHODS: We studied 161 primary melanomas, 45 lymph node metastases, and 16 distant metastases of 183 patients with MM. We used immunohistochemistry to assess PIWIL3 protein expression in situ. The relationship between the immunoreactivity of PIWIL3 and clinical data was statistically evaluated. RESULTS: We observed a significantly (P = 0.000059) higher median immunoreactivity score in primary melanomas (4.9; range, 0.1-6), lymph node metastases (5.1; range, 3.3-6), and distant metastases (5.6; range, 4.5-6). PIWIL3 was expressed significantly higher (P = 0.0002) in primary nodular melanomas and acral melanomas (5.2; range, 3.4-6) when compared to other melanoma subtypes (4.7; range, 0.1-6). On univariate analysis, a significant positive correlation was observed between primary melanoma PIWIL3 expression and tumor thickness (r = 0.2; P = 0.014). On univariate and multivariate analysis, PIWIL3 did not prove to be an independent predictor for melanoma relapse or death. CONCLUSIONS: Our data indicate that PIWIL3 protein expression is elevated in more aggressive primary MM and metastatic disease. As also observed in other malignancies, PIWIL3 seems to play a role in MM progression.

Downregulation of Piwil3 suppresses cell proliferation, migration and invasion in gastric cancer.

BACKGROUND: Gastric cancer is one of the most common malignancies worldwide. Recent studies reported that Piwil3 was overexpressed in various cancers, including gastric cancer (GC). This study was intended to investigate its function and mechanism in GC progress. METHODS: Quantitative real time PCR(RT-PCR) and western blotting assays were utilized to measure mRNA and protein expression levels, respectively. SiRNA transfection was performed to suppress the expression of Piwil3. CCK-8 assay, cell invasion and migration assays were used to determine the cell proliferative, cell invasive and migratory ability. RESULTS: The expression of Piwil3 was significantly increased in GC tissues compared with matched normal tissues. The specific siRNA significantly inhibited the protein and mRNA expressions of Piwil3, and effectively inhibited the proliferation and induced G0/G1 phase arrest in GC cells. Downregulation of Piwil3 significantly suppressed the migration and invasion of GC cells. Moreover, the downregulation of Piwil3 also significantly suppressed the tumor volumes in nude mice. Mechanism investigation showed that the downregulation of Piwil3 significantly decreased the mRNA and protein expressions of metastasis-related genes, including RhoC, MTA1, MMP2 and MMP9, and also modulated the phosphorylation levels of JAK2 and STAT3 but not their protein levels. CONCLUSIONS: These findings indicate that overexpression of Piwil3 promotes the proliferation, migration and invasion of GC cells partially through JAK2/STAT3 signal pathway.