Traditionally, by means of measuring the assay of PSA protein in the blood, folk with high risks in PCa screen for that illness. However, in the United States, the US Preventive Services Task Force (USPSTF) reviewed the evidence on the benefits and harms of PSA-based screening for PCa and subsequent treatment of screen-detected PCa [25]. For men aged 55 to 69 years, the decision to undergo periodic PSA-based screening for PCa should be various from person to person and should take the balance of the possible benefits and troubles of screening PSA with their clinician [26]. Through screening PSA, for some men, it just gives the patients a limited potential profit of the reductions in risk of dying of PCa and metastatic disease in the end stage [27]. Many men will suffer potential harms of screening, including false-positive results that entail extra testing and even, invasive prostate biopsy, to separate them from the real patients; overdiagnosis and overtreatment; and it may arouse a lot of treatment complications, such as incontinence and erectile dysfunction, which wastes unnecessary time, influence the normal life and lowers the quality of life [28–30]. Clinicians should not screen men who do not express a preference for screening (C recommendation) [31–33]. The USPSTF recommends against PSA-based screening for PCa in men 70 years and older (D recommendation) [25, 34, 35]. As there is progressively amounts of argument and distrust about the specificity and sensitivity of PSA, it is essential to develop more dependable biomarkers for early screening of PCa. Recent developments in the detection of lncRNAs have acknowledged lineage- and cancer-specific biomarkers that may be applicable in the clinical utilization of PCa. Herein, we will combine our analysis of RNA-seq datasets, from 5 patient samples, including PCa and adjacent benign prostate tissue with the other investigation to exploit and corroborate differentially expressed lncRNA connected with PCa. After we concluded the lncRNA candidates, which had characteristics of the most significant changes, we proved the consistency of RNA-seq results and qRT-PCR outcomes by extending the clinical samples that consisted of another 5 tumor specimens and 7 para-cancerous/benign contrasts through prostate biopsy. The top each twenty up-regulated and down-regulated lncRNAs was listed in Table 4.
We noticed that NR_125857, related to the gene EVADR, ranked the first line of upregulation in our database. EVADR is the written abbreviation of Endogenous retroViral-associated ADenocarcinoma RNA (EVADR), by analyzing RNA-seq data derived from colorectal tumors and matched normal control tissues [36]. This lncRNA demonstrated nominal to low expression in normal tissue, but is significantly upregulated in cancer, particularly in colon, rectal, lung, stomach and pancreas adenocarcinomas. It was reported the EVADR lncRNA determined the promoter activity of the MER48 long terminal repeat (LTR) in vitro, mapped the genome-wide MER48 LTR expression [36, 37]. Regardless of a biological function, the specificity of EVADR activation in adenocarcinomas coupled with the poorer survival probability that tracks with elevated EVADR expression suggested that further characterization of EVADR as a candidate adenocarcinoma biomarker is warranted [36].Nevertheless, the original article did not mention any details about the EVADR in PCa. In our study, it was totally clear that the expression of NR_125857 is up-regulated in PCa by RNA-seq and qPCR. Since it was described as the highest upregulated lncRNA in our research, it seemed to be promising in the PCa research, for, without any doubt, PCa is also a kind of adenocarcinoma. The mechanism mediated by the high expression of NR_125857 in PCa requires further cavernous research and investigation.
In the top five of the upregulation in lncRNA, NR_015342 and ENST00000412654 are associated with the PCa3, accounting for a large proportion. PCa3 was located on chromosome 9q21-22 [38]. PCa3, as one of the oldest identified lncRNAs, is an accepted diagnostic urinary biomarker for PCa [39]. Because PCa3 is over-expressed in 95% of PCa, with up to 100-fold up-regulation compared to adjacent non-neoplastic cells [40, 41]. Highly overexpression of PCa3 in PCa tissue was found to be a potential non-invasively prediction of prostate biopsy which might be a promising biomarker in clinical diagnosis [42]. However, PCa3 assays also have limited utility in detecting men with higher grade diseases due to low PCa3 levels [43]. For instance, a patient was observed to be negative for PCa as assessed by urinary PCa3, but was later diagnosed to have very high-grade disease (Gleason Score 9) and high Decipher metastasis risk [44]. Thus, it warns us that single usage of PCa3 as a stand-alone marker for PCa may deliver false negative outcomes for patients with higher grade tumor.
Ranking at the third up-regulation of genes, NR_109832 suggests the gene PCAT14 also play an important role in PCa tumorigenesis. PCAT-14 is commonly up-regulated in primary tumors. PCAT14 is an AR-regulated transcript while PCAT14 is highly expressed in low grade disease and loss of PCAT14 predicts for disease aggressiveness and recurrence, and its overexpression suppresses invasion of PCa cells [45]. PCAT14 lower expression is significantly prognostic for multiple clinical endpoints supporting its significance for predicting metastatic disease that could be used to improve patient management [46].
The sixth up-regulated gene symbol is related with AP001610.9, and ENST00000415820 may links to LOC111099027, LOC105372809, TMPRSS2 and MX1. TMPRSS2, also named as PP9284 or PRSS10, is transmembrane serine protease 2, which is a member of the membrane-anchored serine proteases family [47]. It has been figured out that TMPRSS2 mediates a proteolytic cascade regulated by androgen signaling, which promotes the progression, invasion, and metastasis of PCa cells by activating the matriptase and disordering the extracellular matrix [48–50]. TMPRSS2 mainly affects degradation of extracellular matrix nidogen-1 and laminin β1 [48]. Therefore, it indicates an innovative approach for targeting these two proteases in treatment development, and the intimate connection between tumor cells and extracellular matrix in the PCa. Moreover, MX1 has many aliases, such as IFI-78K, IFI78, MX, MxA and lncMX1-215. It belongs to the class of dynamin-like large guanosine triphosphatases (GTPases) acknowledged to be involved in intracellular vesicle trafficking and organelle homeostasis, which chiefly participates in the cellular antiviral response against a wide range of RNA viruses, including influenza viruses and members of the bunyavirus family [51]. It is an interferon stimulated antiviral protein that is required for a complete antiviral response [52]. Preceding study found that down-regulation of MxA in LNCaP cells by dihydrotestosterone suggests that MxA appears to be meaningfully associated with cell cycle and further cancer development while the loss of MxA expression leads to increased metastasis and decreased sensitivity to Docetaxel, which shows that MxA expression could regulate the outcome of chemotherapy [53, 54].
Although the ENST00000365110 ranked the eighth contender, its interrelated gene SNORA62 has the full name as small nucleolar RNA, H/ACA box 62. snoRNAs are one of the most ancient and numerous families of non-protein-coding RNAs. Eukaryotic snoRNAs are conserved from archaeal sRNAs in both function and structure [55]. Therefore, the main function of snoRNAs - to guide site-specific rRNA modification - is the same in archaea and all eukaryotic lineages [56]. Owing to the presence of a conserved H box (5′-ANANNA-3′) and an ACA sequence, H/ACA box snoRNAs form a double hairpin structure [55]. The box H/ACA snoRNAs direct the site-specific pseudouridylation of pre-rRNAs [57].Recent findings have proven that deregulation of the pseudouridinylation process is connected with the progression of PCa [58]. Another research demonstrates SNORA62 are encoded from the host gene RPSA or Laminin receptor (LAMR) while it is observed that the mutations in the LAMR/RPSA gene may be related to congenital asplenia, the inborn absence of spleen [59, 60].
The lowest down-regulation lncRNA is the anonymous lnc-MYL2-4:1. In our study, it suggests this lncRNA is interrelated to myosins, which are a large and diverse family of molecular motors important for cell migration and motility [61]. In PCa, Myo1b, Myo6, Myo9b, Myo10, and Myo18a were expressed at higher levels in high metastatic potential cells, and especially Myo1b and Myo10 were expressed at higher levels in metastatic tumors [62–64]. Changes in expression of several myosin isoforms may contribute to metastasis in PCa [62]. Though the outcome of qPCR in this study was no significant different in PCa tissues and normal tissues, the exact interaction between our candidate lncRNA and myosin is still needed to research.
The second down-regulation lncRNA lnc-C19orf73-1:1 is related to histidine rich calcium binding protein (HRC). The HRC is a novel regulator of sarcoplasmic reticulum (SR) Ca2+-uptake, storage and release, so the HRC plays a pivotal role in Ca2+-homeostasis.2 Calcium (Ca2+) is an essential intracellular signaling molecule involved in the regulation of cancer progression, including cell proliferation, apoptosis, invasion and migration [65, 66]. It has been proved that HRC promotes growth of hepatocellular carcinoma in vitro and in vivo [67]. Furthermore, HRC also plays a significant role in myocyte differentiation and in anti-apoptotic cardioprotection against ischemia/reperfusion induced cardiac injury [68].
Lnc-MID1-4:1, located on the chromosome X, is associated with Rho GTPase activating protein 6. Rho GTPases have been figured out to be critical signal transducers, which mediate growth factor-induced changes to the actin cytoskeleton and activating the phagocyte NADPH oxidase [69]. As a result, they get involved in abundant cellular processes. For example, cell migration, cell survival, transcriptional regulation and vesicle transferring [70]. The deleted in liver cancer 1 (DLC-1) gene encodes a GTPase activating protein that acts as a negative regulator of the Rho family of small GTPases, and DLC-1 is assumed as a bona fide tumor suppressor gene in different types of human cancer [71]. It hints that the down-regulation of Lnc-MID1-4:1 may influence on the particular cellular functions in PCa.
lnc-PDCD11-5:1 is connected to neutralized E3 ubiquitin protein ligase 1. The E3 ubiquitin ligase NEDD4 negatively regulates HER3/ErbB3 level and signaling [72]. Many preceding studies reveals NEDD4 has been acknowledged to play a critical role in the regulation of a number of membrane receptors, endocytic machinery components and the tumor suppressor PTEN [73]. The loss of PTEN expression was associated with worse survival and shorter time on abiraterone treatment [74]. Ubiquitin Ligases are also involved in the regulation of Wnt, TGF-β, and Notch Signaling Pathways [75].
There is scarcely any information about the rest of up-regulation lncRNAs, such as ENST00000558010, ENST00000365110, NONHSAT072254, NONHSAT072236, lnc-PTEN-11:1, and ENST00000439575. More experiments are needed to prove their impression and function.
In our analysis, there are ten qualified samples, so our study still has boundedness in the number of samples. Yet the feature of our study was that our patients are typical Mongoloid men and our results exhibited very specificity in east Asia area. Moreover, to highlight the coherence of our outcomes and practical issues and value, we further extended the clinical samples for qPCR and drew the survival curves of meaningful genes of lncRNAs after the confirmation of qPCR. The top seven upregulation lncRNAs, like NR_125857, NR_015342, NR_109832, ENST00000412654, lnc-AC110080.1-5:1, ENST00000415820 and ENST00000558010 are promising research candidates for extra investigation. The present study of lncRNAs in PCa tissues is a proof-of-principle that lncRNAs have a possible character in PCa formation and progression. As demonstrated in the tables, there are so many lncRNAs has the relationship with PCa, the information, even, the name of their majority is blank. Lots of verification test are need to be completed. Our current study on the potential link between lncRNAs and PCa presents a novel analysis for further investigations into the biomarker and target genes of such lncRNAs, leading to clinical research for the disease.
The treatment paradigm of PCa has progressed rapidly in the last decade due to wider availability and choice of therapy. Thus, we have the reason to believe in, with the deep investigation, the potential mechanism of lncRNA will be disclosed stepwise, which provides new breakthroughs in the early diagnosis, prognosis, and therapy targets of PCa.