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Background/Aim: Long noncoding RNA TARID (lncRNA TARID) can activate the tumor suppressor TCF21 in tumorigenesis by inducing promoter demethylation. However, the impact on lncRNA TARID and its variants of coronary artery disease (CAD) are poorly understood. Methods We performed a case-control study enrolling 949 case patients and 892 controls to assess genotype. Five variants were genotyped by TaqMan assay. 20 case patients and 20 controls were used to evaluate the expression of lncRNA TARID. The qRT-PCR and cell cycle analysis were applied to examined cell proliferation and cell distribution. Results This study indicated that rs2327433 GG genotype was associated with CAD risk adjusting for traditional risk factors (OR=2.74, 95%CI: 1.10-6.83, P=0.03). Our results analyses revealed that the genotype of rs2327433 was related to the proportion of CAD patients with left anterior descending artery disease and left circumflex artery disease (P=0.025 and P=0.025, respectively). The results showed that the minor allele frequency of rs2327433 was significantly correlated with the severity of the disease (P=0.029). The eQTL analysis showed that rs2327433 may affect the transcription factors TCF21 regulated by lncRNA TARID. We found that TARID silencing regulated the cell proliferation and altered cell cycle progression by induced upregulation of CDK1 and PCNA. Conclusions SNP rs2327433 in lncRNA TARID was associated with CAD risk and the severity of CAD in Chinese Han population. Furthermore, SNP rs2327433 may affect the expression of atherosclerosis-related transcription factor TCF21 regulated by lncRNA TARID. Finally, our study provided a new lncRNA-dictated regulatory mechanism participating in cell proliferation.

Genetic alterations in the cell cycle pathway are common in head and neck squamous cell carcinoma (HNSCC). We identified four novel HNSCC susceptibility loci (CDKN1C rs452338, CDK4 rs2072052, E2F2 rs3820028 and E2F2 rs2075993) through a two-stage matched case–control study. There was a combined effect among the four single nucleotide polymorphisms (SNPs), as the number of risk genotypes increased, the risk of HNSCC displayed an increasing trend (Ptrend < 0.001). And there were multiplicative interactions between rs452338 and rs2072052, rs2072052 and rs3820028, rs2072052 and rs2075993. Functional bioinformatics analysis and dual-luciferase reporter assay revealed that E2F2 rs2075993 T>C reduced the stability of E2F2 3’-UTR secondary structure and affected the binding of E2F2 to miR-940, which was up-regulated in HNSCC tumor tissues (P = 2.9e−8) and was correlated with poor overall survival of HNSCC (HR = 1.39, 95% CI = 1.02–1.90). In vitro assays, we discovered that the expression of miR-940 was regulated by METTL3, and miR-940 promoted the proliferation, migration and invasion, and inhibited the senescence and autophagy of tumor cells. In terms of mechanism, compared with rs2075993 allele T, we found that the protective variant rs2075993 allele C interfered with the translational inhibition of E2F2 by miR-940, resulting in increased expression of E2F2 protein, which further reduced the proliferation, migration, invasion, and increased the senescence of tumor cells.

Key points In rats RNA-Seq analysis showed sexual dimorphism in gene expression across the life-course between 110 and 650 days of life. Fourteen times more liver transcriptome and six times more pathway changes were observed in males compared with females. We observed significant changes in several signaling pathways during ageing. In this study, we focussed our bioinformatic analysis to changes in genes and protein product related to cell cycle and cellular senescence pathways. Males showed decreased protein product and expression of the key genes CDK2, CDK4 responsible for cell cycle progression while females increased protein product and expression of p21 and p15 key genes responsible for cell cycle arrest. We conclude that normative rat hepatic ageing involves changes in cellular pathways that control the cell cycle arrest but through changes in different genes in males and females. These findings identify mechanisms that underlie the well-established sexual dimorphism in ageing. Abstract At the molecular level, cellular ageing involves changes in multiple gene pathways. Cellular senescence is both an important initiator and a consequence of natural ageing. Senescence results in changes in multiple cellular mechanisms that result in a natural decrease in cell cycle activity. Liver senescence changes impair hepatic function. Given the well-established sexual dimorphism in ageing, we hypothesized that the natural hepatic ageing process is driven by sex-dependent gene mechanisms. We studied our well-characterized normal, chow-fed rat ageing model, lifespan ∼850 days, in which we have reported ageing of metabolism, reproduction and endocrine function. We performed liver RNA-seq on males and females at 110 and 650 days (d) to determine changes in the cell cycle and cellular senescence signaling pathways. We found that natural liver ageing shows sexual dimorphism in these pathways. RNA-seq revealed more male (3967) than female (283) differentially expressed genes (DEG) between 110d and 650d. Cell cycle pathway signaling changes in males showed decreased protein and expression of key genes (CDK2, CDK4, Cycd and PCNA) and increased p57 at 650d vs. 110d. In females, protein and gene expression of cell growth regulators, e.g. p15 and p21, that inhibit cell cycle G1 progression were increased. The cell senescence pathway also showed sexual dimorphism. Igfbp3, mTOR and p62 gene and protein decreased in males while Tgfb3 increased in females. Understanding the involvement of cell cycling and cellular senescence pathways in natural ageing will advance evaluation of mechanisms associated with altered ageing and frailty trajectories. This article is protected by copyright. All rights reserved.

Cell cycle progression is a critical component of cell proliferation, and continuous proliferation is one of the hallmarks of cancer. Components regulating the E2F pathway have been identified in nearly every human malignancy and many of them including E2F transcription factors themselves play major roles in cancer progression, metastasis and treatment response of breasts cancer. Their activity therefore is expected to reflect tumor aggressiveness and responsiveness to therapy. We scored 3,905 tumors of nine breast cancer cohorts for this activity based on their 200 gene expression for the Hallmark E2F targets gene set. As expected, tumors with a high score had increased expression of cell proliferation-related genes, including G2M checkpoint, MYC targets v1 and v2, MITOTIC spindle, MTORC1 signaling, UNFOLDED protein response, and DNA repair in both the TCGA and METABRIC cohorts (false discovery rate < 0.001 in both cohorts). A high score was significantly associated with greater MKI67 expression (p < 0.001 in both cohorts), histological grade (p < 0.001 in both cohorts), and AJCC pathological stage (p < 0.001 in both cohorts). And Indel and single nucleotide variation neoantigen loads were associated with a high E2F pathway score (p = 0.006 and 0.047 respectively). Furthermore, the E2F pathway score correlated positively with copy number alteration (Spearman r = 0.55, p < 0.001). Intra-tumoral genome heterogeneity and proliferation score were significantly associated with the E2F pathway score as well (p < 0.001). The high E2F pathway score group demonstrated significantly higher fractions of not only pro-cancerous regulatory T cells, helper T cell (Th2), but also anti-cancerous CD4 memory T cell, helper T cell (Th1), and M1 macrophage as well as B cells compared to the low score group in the TCGA cohort (p < 0.001). Similar trends were observed in the METABRIC cohort. Furthermore, metastatic tumors had higher E2F scores than the primary tumors from which they arose especially luminal and normal subtype (p = 0.006 and p < 0.001). Interestingly, metastases with a high E2F score were associated with significantly worse PFS in the whole cohort, as well as patient sub-groups with local recurrence and with liver metastasis (p = 0.018, p = 0.025 and p = 0.027). Additionally, the E2F pathway score was significantly decreased with good response to chemotherapy (p < 0.001) and demonstrated higher pCR rate after neoadjuvant therapies in the high E2F pathway score group of estrogen receptor (ER)-positive/HER2-negative cancer (p < 0.001). The E2F score was significantly associated with expression of cyclin-dependent kinase (CDK)-related genes, including CCNE1, CDKN2A, CDKN2D, CDK2, CDK4 and CDK6 (all p < 0.001), and immune checkpoint molecule-related genes including PD-L1/2, CTLA4, IDO1, LAG3 and TIGIT (p = 0.013, 0.014, < 0.001, < 0.001, < 0.001 and 0.002, respectively). These results were validated by other cohort. Finally, the E2F score was strongly correlated with sensitivity to CDK inhibition in ER+/HER2- breast cancer cell-lines (Spearman r = 0.90, p = 0.04). In conclusion, the E2F score is a marker of breast cancer aggressiveness and predicts responsiveness of ER+/HER2- patients to neoadjuvant chemotherapy and possibly to CDK and immune checkpoint inhibitors. Citation Format: Masanori Oshi, Hideo Takahashi, Yoshihisa Tokumaru, Ryusei Matsuyama, Itaru Endo, Kazuaki Takabe. The E2F cell cycle pathway score to predict treatment response among patients with breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-35.

Vitamin C has re-emerged as a promising anticancer agent. This study attempts to analyze the differential gene expression of profiles GSE11919 to look for some clues, and the most significant cell cycle pathway caused by vitamin C was identified by integrated bioinformatics analysis. Inspired by this, we investigated the effect of vitamin C treatment on gastric carcinoma cells by detection of cell cycle, apoptosis, and autophagy. Vitamin C significantly elevated the percentage of cells at G0/G1 phase, whereas the percentage of S phase cells was decreased. Meanwhile, vitamin C treatment resulted in downregulation of cell cycle-related protein Cyclin D1. We deduced that the downregulation of Cyclin D1 by vitamin C accompanied by significantly increased 5′AMP-activated protein kinase and induced autophagy in MKN45 cells. These results suggest that vitamin C has the antiproliferation effect on gastric carcinoma cells via the regulation of cell cycle and autophagy by Cyclin D1.

DNA damage results in mutations and plays critical roles in cancer development, progression, and treatment. Targeting DNA damage response in cancers by inhibiting poly-(ADP-ribose) polymerases (PARPs) offers an important therapeutic strategy. However, the failure of PARP inhibitors to markedly benefit patients suggests the necessity for developing new strategies to improve their efficacy. Here, we show that the expression of cyclin-dependent kinase 4/6 (CDK4/6) complex members significantly correlates with mutations (as proxies of DNA damages), and that the combination of CDK4/6 and PARP inhibitors shows synergy in both RB-proficient and RB-deficient breast cancer cells. As PARPs constitute sensors of DNA damage and are broadly involved in multiple DNA repair pathways, we hypothesized that the combined inhibition of PARPs and DNA repair (or repair-related) pathways critical for cancer (DRPCC) should show synergy. To identify druggable candidate DRPCC(s), we analyzed the correlation between the genome-wide expression of individual genes and the mutations for 27 different cancer types, assessing 7146 exomes and over 1,500,000 somatic mutations. Pathway enrichment analyses of the top-ranked genes correlated with mutations indicated “cell cycle pathway” as the top candidate DRPCC. Additionally, among functional cell-cycle complexes, the CDK4/6 complex showed the most significant negative correlation with mutations, also suggesting that combined CDK4/6 and PARP inhibition might exhibit synergy. Furthermore, combination treatment showed synergy in not only RB-proficient but also RB-deficient breast cancer cells in a reactive oxygen species-dependent manner. These findings suggest a potential therapeutic strategy to improve the efficacy of PARP and CDK4/6 inhibitors in cancer treatment.

Objective: Bladder cancer ranks 10th among the most common cancers worldwide, effecting mostly man than women. The aim of this study is to perform a detailed gene expression analysis of bladder urothelial carcinoma to reveal altered molecular mechanisms and to find potential biomarkers for this cancer. Materials and Methods: Bladder urothelial carcinoma RNA-seq data from TCGA and normal bladder samples from GTEx were analyzed by using GEPIA. Differentially expressed genes were annotated to GO-BP and KEGG pathway terms with DAVID and PPI networks were constructed by STRING. The association of upregulated cell cycle pathway proteins and patient survival was further investigated. Results: Upregulated genes mainly annotated to cell cycle, p53 signaling and oocyte meiosis and maturation pathways and cell cycle related GO-BP terms. Downregulated genes mostly annotated to adhesion, ECM-receptor interaction, vascular smooth muscle contraction and cardiomyopathy related KEGG pathways and muscle related GO-BP terms. The protein products of six cell cycle genes, which were upregulated in bladder urothelial carcinoma, showed significant association with patient survival. Conclusion: The results of this study showed altered molecular mechanisms and increased our understanding in bladder urothelial carcinoma, proposed potential prognostic biomarkers.

The tumor microenvironment (TME) is comprised of tumor cells, infiltrating immune cells, and stroma. Multiple reports suggest that the immune cell infiltration (ICI) in TME is strongly associated with responsiveness to immunotherapy and prognosis of certain cancers. Thus far, the ICI profile of pancreatic carcinoma (PC) remains unclear. Here, we employed two algorithms to characterize the ICI profile of PC patients. Based on our results, we identified 2 ICI patterns and calculated the ICI score by using principal component analysis. Furthermore, we revealed that patients with low ICI scores had a better prognosis, compared to high ICI scores. Moreover, we discovered that a low tumor mutation burden (TMB) offered better overall survival (OS), relative to high TMB. In this study, a high ICI score referred to elevated PD-L1/TGF-β levels, increased activation of cell cycle pathway and DNA repair pathway, as well as reduced expression of immune-activation-related genes. We also demonstrated that three metabolic pathways were suppressed in the low ICI score group. These data may explain why a high ICI score equates to a poor prognosis. Based on our analysis, the ICI score can be used as an effective predictor of PC prognosis. Hence, establishing an ICI profile, based on a large patient population, will not only enhance our knowledge of TME but also aid in the development of immunotherapies specific to PC.

Background Recent evidences indicated that shear stress is critical in orchestrating gene expression in cardiovascular disease. It is necessary to identify the mechanism of shear stress influencing gene expression in physiology and pathophysiology conditions. This paper aimed to identify candidate hub genes and its transcription factors with bioinformatics. Methods We analyzed microarray expression profile of GSE16706 to identify differentially expressed genes (DEGs) in low shear stress (1 dyne/cm2) treated human umbilical vein endothelial cells (HUVECs) compared with static condition for 24 h. Results 652 DEGs, including 333 up-regulated and 319 down-regulated DEGs, were screen out. Functional enrichment analysis indicated enrichment items mainly included cytokine-cytokine receptor interaction and cell cycle. Five hub genes (CDC20, CCNA2, KIF11, KIF2C and PLK1) and one significant module (score = 17.39) were identified through protein–protein interaction (PPI) analysis. Key transcriptional factor FOXC1 displayed close interaction with all the hub genes via gene-transcriptional factor network. Single-gene GSEA analysis indicated that CDC20 was linked to the G2M_CHECKPOINT pathway and cell cycle pathway. Conclusions By using integrated bioinformatic analysis, a new transcriptional factor and hub-genes network related to HUVECs treated with low shear stress were identified. The new regulation mechanism we discovered may be a promising potential therapeutic target for cardiovascular disease.

Molecular chaperones play important roles in regulating various cellular processes and malignant transformation. Expression of some subunits of molecular chaperone CCT/TRiC complex have been reported to be correlated with cancer development and patient survival. However, little is known about the expression and prognostic significance of Chaperonin Containing TCP1 Subunit 2 (CCT2). CCT2 is a gene encoding a molecular chaperone that is a member of the chaperonin containing TCP1 complex (CCT), also known as the TCP1 ring complex (TRiC). Through the Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) databases, we systematically reviewed a total of 2,994 cases with transcriptome data and analyzed the functional annotation of CCT2 by Gene ontology and KEGG analysis. Univariate and multivariate survival analysis were performed to investigate the prognostic value of CCT2 in breast cancer. We found CCT2 was significantly upregulated in various tumors. In breast cancer, CCT2 expression was significantly upregulated in HER2-positive (HER2+) group, and more malignant group. In addition, we investigated correlations between CCT2 and other CCT members. Interestingly, almost all CCTs expression were positively correlated with each other, but not CCT6B. Survival analysis suggested that CCT2 overexpression was independently associated with worse prognosis of patients with breast cancer, especially in luminal A subtype. In summary, our results revealed that CCT2 might be involved in regulating cell cycle pathway, and independently predicted worse prognosis in breast cancer patients. These findings may expand understanding of potential anti-CCT2 treatments. To our knowledge, this is the largest and most comprehensive study characterizing the expression pattern of CCT2 together with its prognostic values in breast cancer.

BACKGROUND: The D-type cyclin and cyclin dependent kinase 4/6 (CDK) complex phosphorylates retinoblastoma protein, thereby driving cell cycle progression. This process is blocked by inhibitors of CDK4/6. As part of the Molecular Screening and Therapeutics program, this phase IIa trial tested the clinical activity of CDK4/6 inhibitor monotherapy in tumors with cell cycle pathway alterations.PATIENTS AND METHODS: Eligible patients ≥ 18 years old, with advanced or metastatic solid cancers, along with amplification of CDK4/6, CCND1/2/3, or loss of function alterations in CDKN2A were recruited. The primary objective of this signal-seeking trial was to evaluate the clinical activity of palbociclib – a composite of objective responses and the ratio of time to progression (TTP) on palbociclib, to TTP on treatment preceding trial entry.RESULTS: Ten patients had CDK4/CDK6 or Cyclin D1 amplifications, six patients had CDKN2A deletions. After a median follow-up of 35 months, there were no objective responses. Seven patients had stable disease and one had non-complete response/non-progressive disease (non-CR/non-PD) based on evaluation of a non-target lesion. Two of these seven patients maintained stable disease for at least 6 months, as did the patient with non-CR/non-PD. Median PFS and OS were 3.5 and 11.0 months respectively. No unexpected toxicities were observed. Translational correlates yielded strategies for targeting cell cycle interactions with other molecular pathways and the immune system.CONCLUSION: Palbociclib monotherapy was not associated with any objective responses, but stable disease lasting at least 6 months was observed in 19% of patients. There was no clear relationship with alteration type or histotype. The signals of immune activation provide insights into the design of future trials, with a combination approach adding checkpoint blockade to CDK4/6 inhibition.

BackgroundLethal genes have not been systematically analyzed in breast cancer which may have significant prognostic value. The current study aims to investigate vital genes related to cell viability by analyzing the CRISPR-cas9 screening data, which may provide novel therapeutic target for patients.MethodsGenes differentially expressed between tumor and normal tissue from the Cancer Genome Atlas (TCGA) and genes related to cell viability by CRISPR-cas9 screening from Depmap (Cancer Dependency Map) were overlapped. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis was conducted to identify which pathways of overlapped genes were enriched. GSE21653 set was randomized into training and internal validation dataset at a ratio of 3:1, and external validation was performed in GSE20685 set. The least absolute shrinkage and selection operator (LASSO) regression was used to construct a signature to predict recurrence-free survival (RFS) of breast cancer patients. Univariate and multivariate Cox regression were used to evaluate the prognostic value of this signature. Differentially expressed genes (DEGs) between high-risk and low-risk patients were then analyzed to identify the main pathways regulated by this signature. Weighted correlation network analysis (WGCNA) was conducted to recognize modules correlated with high risk. Enrichment analysis was then used to identify pathways regulated by genes shared in the overlapped genes, DEGs, and WGCNA.ResultsA total of 86 oncogenes were upregulated in TCGA database and overlapped with lethal genes in Depmap database, which were enriched in cell cycle pathway. A total of 51 genes were included in the gene signature based on LASSO regression, and the median risk score of 2.36 was used as cut-off to separate low-risk patients from high-risk patients. High-risk patients showed worse RFS compared with low-risk patients in internal training, internal validation, and external validation dataset. Time-dependent receiver operating characteristic curves of 3 and 5 years indicated that risk score was superior to tumor stage, age, and PAM50 in both entire and external validation datasets. Cell cycle was the main different pathway between the high-risk and low-risk groups. Meanwhile, cell cycle was also the main pathway enriched in the 25 genes which were shared among 86 genes, DEGs, and WGCNA.ConclusionCell cycle pathway, identified by CRISPR-cas9 screening, was a key pathway regulating cell viability, which has significant prognostic values and can serve as a new target for breast cancer patient treatment.

BackgroundMolecular characteristics are essential for the classification and grading of gliomas. However, diagnostic classification of midline glioma is still debatable and substantial molecular and clinical heterogeneity within each subgroup suggested that they should be further stratified. Here, we studied the mutation landscape of Chinese midline glioma patients in hope to provide new insights for glioma prognosis and treatment.MethodsTissue samples from 112 midline glioma patients underwent next-generation sequencing targeting 425 cancer-relevant genes. Gene mutations and copy number variations were investigated for their somatic interactions and prognostic effect using overall survival data. Pathway-based survival analysis was performed for ten canonical oncogenic pathways.ResultsWe identified several currently established diagnostic and prognostic biomarkers of glioma, including TP53 (33%), EGFR (26%), TERT (24%), PTEN (21%), PIK3CA (14%), ATRX (14%), BRAF (13%), and IDH1/2 (6%). Among all genetic aberrations with more than 5% occurrence rate, six mutations and three copy number gains were greatly associated with poor overall survival (univariate, P < 0.1). Of these, TERT mutations (hazard ratio [HR], 3.00; 95% confidence interval [CI], 1.37–6.61; P = 0.01) and PIK3CA mutations (HR, 2.04; 95% CI, 1.08–3.84; P = 0.02) remained significant in multivariate analyses. Additionally, we have also identified a novel MCL1 amplification (found in 31% patients) as a potential independent biomarker for glioma (multivariate HR, 2.78; 95% CI, 1.53–5.08; P < 0.001), which was seldom reported in public databases. Pathway analyses revealed significantly worse prognosis with abnormal PI3K (HR, 1.81; 95% CI, 1.12–2.95; P = 0.01) and cell cycle pathways (HR, 1.97; 95% CI, 1.15–3.37; P = 0.01), both of which stayed meaningful after multivariate adjustment.ConclusionsIn this study, we discovered shorter survival in midline glioma patients with PIK3CA and TERT mutations and with abnormal PI3K and cell cycle pathways. We also revealed a novel prognostic marker, MCL1 amplification that collectively provided new insights and opportunities in understanding and treating midline gliomas.

Background Cell division cycle-associated 7 (CDCA7), as a member of the cell division cycle associated family, was reported to be aberrantly expressed in both solid tumors and hematological tumors, suggesting its essential role in promoting tumorigenesis. Hence, we aimed to explore its comprehensive roles of overall survival (OS) in clear cell renal cell carcinoma (ccRCC) and emphasize its associations with immunity. Methods The RNA sequencing data and corresponding clinical information were downloaded from The Cancer Genome Atlas (TCGA) database. Gene set enrichment analysis (GSEA) was adopted to explore CDCA7 associated signaling pathways. Univariate and multivariate Cox regression analyses were carried out to assess independent prognostic factors. Furthermore, roles of CDCA7 in human immunity were also investigated. Results Our results suggested that CDCA7 was overexpressed in ccRCC and its elevated expression was related to shorter OS (P Conclusions CDCA7 could serve as an independent prognostic factor for ccRCC and it was closely related to MSI, TMB, and immunity.

Ovarian cancer (OV) is one of the most common female malignancies with high morbidity and mortality, but its mechanism is not fully understood. The circadian clock is involved in the regulation of the immune system and the tumor microenvironment, regulating biological processes and behaviors in multiple ways. Circadian rhythm disorders are considered a risk factor for tumorigenesis. Multi-omics analysis was performed to comprehensively illustrate the roles of circadian clock genes in OV, we found that most of circadian clock genes undergo epigenetic alterations in OV and are strongly correlated with overall and progression-free patient survival. These clock genes are mainly involved in the inhibition of Apoptosis pathway, Cell Cycle pathway and DNA Damage Response pathway, as well as the activation of RAS/MAPK pathway and RTK pathway. Drug sensitivity model indicate that the expression of core clock genes may associate with drug resistance. Further, immune infiltrates analysis shows that different mutant forms of core genes can not only suppress immune infiltration, but also affect clinical outcome of ovarian cancer patients. Overall, our results may provide novel insights for the potential selection of immunotherapeutic targets.

In this study, we investigate how drugs systemically affect genes via pathways by integrating information from interactions between chemical compounds and molecular expression datasets, and from pathway information such as gene sets using mathematical models. First, we adopt drug-induced gene expression datasets, then, employ gene set enrichment analysis tools for selecting candidate enrichment pathways, and lastly, implement the inverse algorithm package for identifying gene&ndash, gene regulatory networks in a pathway. We tested LY294002-induced datasets of the MCF7 breast cancer cell lines, and found a CELL CYCLE pathway with 101 genes, ERBB signaling pathway consisting of 82 genes, and MTOR pathway consisting of 45 genes. We consider two interactions: quantity strength depending on number of interactions, and quality strength depending on weight of interaction as positive (+) and negative (&minus, ) interactions. Our methods revealed ANAPC1-CDK6 (&minus, 0.412) and ORC2L- CHEK1(0.951) for the CELL CYCLE pathway, INS-RPS6 (&minus, 3.125) and PRKAA2-PRKAA2 (+1.319) for the MTOR pathway, and CBLB-RPS6KB1 (&minus, 0.141), RPS6KB1-CBLC (+0.238) for the ERBB signaling pathway to be top quality interactions. Top quantity interactions discovered include 12, the CDC (&minus, +) gene family for the CELL CYCLE pathway, 20, PIK3 (&minus, ), 23, PIK3CG (+) for the MTOR pathway, 11, PAK (&minus, ), 10, PIK3 (+) for the ERBB signaling pathway.

Background Skin cutaneous melanoma (SKCM) is one of the most aggressive malignancies with high invasiveness. Chromobox (CBX) family are involved in the regulation of the tumorigenesis, progression, invasion, and apoptosis of many malignancies. Methods The clinical significance and prognostic value of CBX family in SKCM were analyzed via a series of databases, including ONCOMINE, GEPIA, UALCAN, TIMER, GSCALite, DAVID 6.8, GeneMANIA, and LinkedOmics. Results We found that the level of CBX2, CBX3, CBX5, and CBX6 was upregulated while the level of CBX7 and CBX8 was downregulated in tumor tissues in SKCM. Moreover, the mRNA expression of CBX1 and CBX2 was significantly associated with the pathological stage in SKCM. Prognosis analysis revealed that SKCM patients with high CBX5 level and low CBX7 level had a poor prognosis. Immune infiltrations analysis revealed that the expression of CBX family was associated with the abundance of certain immune cells in SKCM. We also found that CBX family were associated with the activation of cell cycle pathway and DNA damage response, and the inhibition of apoptosis pathway. Moreover, enrichment analysis revealed that CBX family and correlated genes were enriched in chromatin modification, PcG protein complex, transcription coactivator activity, protein binding, and RNA splicing. Several Kinase targets (ATM, CDK1, and PLK1) and miRNA targets (MIR‐331, MIR‐296, and MIR‐496) of CBX family were also identified. Conclusion Our study may uncover CBX family–associated molecular mechanisms involved in the tumorigenesis and progression of SKCM and provide additional choice for the prognosis and therapy biomarker for SKCM., Background: Skin cutaneous melanoma (SKCM) is one of the most aggressive malignancies with high invasiveness. Chromobox (CBX) family are involved in the regulation of the tumorigenesis, progression, invasion, and apoptosis of many malignancies. Methods: The clinical significance and prognostic value of CBX family in SKCM were analyzed via a series of databases, including ONCOMINE, GEPIA, UALCAN, TIMER, GSCALite, DAVID 6.8, GeneMANIA, and LinkedOmics. Results: We found that the level of CBX2, CBX3, CBX5, and CBX6 was upregulated while the level of CBX7 and CBX8 was downregulated in tumor tissues in SKCM. Moreover, the mRNA expression of CBX1 and CBX2 was significantly associated with the pathological stage in SKCM. Prognosis analysis revealed that SKCM patients with high CBX5 level and low CBX7 level had a poor prognosis. Immune infiltrations analysis revealed that the expression of CBX family was associated with the abundance of certain immune cells in SKCM. We also found that CBX family were associated with the activation of cell cycle pathway and DNA damage response, and the inhibition of apoptosis pathway. Moreover, enrichment analysis revealed that CBX family and correlated genes were enriched in chromatin modification, PcG protein complex, transcription coactivator activity, protein binding, and RNA splicing. Several Kinase targets (ATM, CDK1, and PLK1) and miRNA targets (MIR‐331, MIR‐296, and MIR‐496) of CBX family were also identified. Conclusion: Our study may uncover CBX family–associated molecular mechanisms involved in the tumorigenesis and progression of SKCM and provide additional choice for the prognosis and therapy biomarker for SKCM.

PurposeCyclin dependent kinase 4/6 inhibitors (CDK4/6i) lead to cell-cycle arrest but also demonstrate antineoplastic activity through triggering T cell-mediated immunity. One of the potential mechanisms responsible for this immunological effect might be qualitative and quantitative changes in human leukocyte antigen (HLA) ligands on the cell surface after treatment with CDK4/6i. These changes may increase the immunogenicity of breast cancer cells offering potential synergies for combinations with cancer immunotherapies.Experimental DesignWe investigated the ability of two CDK4/6 inhibitors (CDK4/6i), Abemaciclib and Palbociclib, to alter the immunopeptidome at subclinical, non-toxic, levels in different breast cancer cell lines. Biochemical isolation of HLA ligands, identification by mass spectrometry and subsequent network analysis after drug treatment were used to characterize the changes in the immunopeptidome. The mechanisms for altered CDK4/6 presentation were explored.ResultsLow-dose treatment with 100nM of Abemaciclib and Palbociclib led to upregulation of cell surface HLA levels and induced hundreds of HLA ligands in breast cancer cell lines. These new ligands were significantly and most strongly enriched for peptides derived from proteins involved in the “G1/S phase transition of cell cycle” pathway and included among others, HLA ligands from CDK4, CDK6, Cyclin D1 and Cyclin E1. An increase in transcript, protein, and subsequent ubiquitination for Cyclin D1, which could lead to enhanced degradation of the target protein, was identified as a potential mechanism for the altered presentation of peptides.ConclusionsCDK4/6i treatment gave rise to drug-induced antigens through cell cycle disruption and increased antigen presentation. Interestingly, these induced HLA ligands are often sourced from the proteins of the CDK4/CDK6/CCND1 complex or more downstream interaction partners, providing evidence that inhibition of a distinct cellular pathway leads to increased presentation of the proteins involved. These findings suggested CDK4/6i provided a tool for highly selective induction of HLA ligands that may be targeted by T cell-based immunotherapeutics.Translational RelevanceThese data demonstrated that low-dose treatment of breast cancer cells with CDK4/6 inhibitors, Abemaciclib and Palbociclib, induced marked changes in presentation of HLA ligands, especially from proteins involved in the G1/S phase transition, the phase in which these drugs arrest the cells. Enhanced ubiquitination and degradation was identified as a mechanism for the altered presentation for one of the relevant proteins. The induced HLA ligands may provide ideal specific targets for combination immunotherapies. The data show for the first time that selective inhibition of a distinct pathway can lead to specific presentation of HLA ligands in breast cancer cells. This work supports the rationale for testing the combination of low-dose CDK4/6i with immunotherapeutic agents, such as immune checkpoint blockade antibodies or T-cell-based approaches specifically directed against one of the induced HLA ligands.

Emerging evidence has indicated that dysregulation of miR-362-3p is involved in the initiation and progression of several types of human cancers. However, the molecular mechanism of miR-362-3p in renal cell carcinoma (RCC) is still not completely clear. In this study, we found that miR-362-3p was frequently down-regulated in human RCC tissues. Overexpression of miR-362-3p in RCC cells significantly suppressed the proliferation, cell cycle and motility in vitro and in vivo via regulating AKT/FOXO3 signaling. We further confirmed that SP1 was a direct target of miR-362-3p. Knockdown of SP1 expression by a small interfering RNA (siRNA) phenocopied the effect of miR-362-3p overexpression in RCC cells. In conclusion, the current results provide evidence for the role of miR-362-3p in the pathogenesis of RCC and thus miR-362-3p may serve as an attractive candidate for RCC therapy.

Leiomyosarcoma (LMS) is characterized by high genomic complexity, and to date, no specific targeted therapy is available. In a genome-wide approach, we profiled genomic aberrations in a small cohort of eight primary tumours, two relapses, and eight metastases across nine different patients. We identified CDK4 amplification as a recurrent alteration in 5 out of 18 samples (27.8%). It has been previously shown that the LMS cell line SK-LMS-1 has a defect in the p16 pathway and that this cell line can be inhibited by the CDK4 and CDK6 inhibitor palbociclib. For SK-LMS-1 we confirm and for SK-UT-1 we show that both LMS cell lines express CDK4 and that, in addition, strong CDK6 expression is seen in SK-LMS-1, whereas Rb was expressed in SK-LMS-1 but not in SK-UT-1. We confirm that inhibition of SK-LMS-1 with palbociclib led to a strong decrease in protein levels of Phospho-Rb (Ser780), a decreased cell proliferation, and G0/G1-phase arrest with decreased S/G2fractions. SK-UT-1 did not respond to palbociclib inhibition. To compare thesein vitrofindings with patient tissue samples, a p16, CDK4, CDK6, and p-Rb immunohistochemical staining assay of a large LMS cohort (n=99patients with 159 samples) was performed assigning a potential responder phenotype to each patient, which we identified in 29 out of 99 (29.3%) patients. Taken together, these data show that CDK4/6 inhibitors may offer a new option for targeted therapy in a subset of LMS patients.

Summary: We systematically investigated the landscape of tumor-suppressor gene (TSG) inactivation events in 33 cancer types by quantitatively measuring their global and local genomic features and their transcriptional and signaling footprints. Using The Cancer Genome Atlas data, we identified with high confidence 337 TSG × cancer events in 30 cancer types, of which 277 were unique events. The majority (91.0%) of these events had a significant downstream impact measured by reduced expression of the TSG itself (cis-effect), disturbance of the transcriptome (trans-effect), or combinatorial effects. Importantly, the transcriptomic changes associated with TSG inactivation events were stronger than the cancer lineage difference, and the same TSGs inactivated in different cancer types tended to cluster together. Several TSGs (e.g., RB1, TP53, and CDKN2A) involved in the regulation of the cell-cycle-formed clusters. Finally, we constructed subnetworks of the TSG × cancer inactivation events, including the local genes frequently disturbed upon the inactivation events. : Jia and Zhao present a pan-cancer analysis of tumor-suppressor gene (TSG) inactivation events. They examine the genetic mutations that lead to TSG inactivation and the functional impact of TSG inactivation events. The results suggest that TSG × cancer inactivation events tend to cluster by TSG function, rather than by cancer lineage. Keywords: tumor suppressor gene, two-hit model, The Cancer Genome Atlas, transcriptome impact, cell cycle pathway, RB1, CDKN2A

S-Adenosylmethionine (SAMe) is a kind of common liver-protection medicine. Recent studies have shown that SAMe has the inhibitory effects on hepatocellular carcinoma (HCC). But the specific mechanism has not been elucidated. Here, we examine the effects and relevant mechanisms of SAMe on human hepatocellular carcinoma cell HepG2 and mouse hepatocyte AML12. We applied the technique of RNA sequencing (RNA-Seq) to identify the differentially expressed genes between HepG2 cells which were treated with SAMe or not. And western blot and Quantitative RT-PCR was used to confirm some of these genes. To investigate the response to SAMe treatment, cell proliferation assay (MTS) and flow cytometry-based assays were carried out. A total of 472 SAMe-related genes were identified by RNA-Seq. We found that differentially expressed genes were enriched in cell cycle related signaling pathway significantly by the KEGG and GO Pathway enrichment analysis. Through the construction of protein-protein interaction network, we observed the module associated with cell cycle is in the core of the whole network. All these results implied that cell cycle pathway may be very important in the regulation of SAMe effected on HepG2 cells. Then the RNA-Seq-characterized genes involved in cell cycle (MCM3, MCM4, and E2F1) were confirmed by Western blot and Quantitative RT-PCR in HepG2 and AML12 cells. MTS analysis showed that SAMe could diminish cell proliferation. And flow cytometry-based assays indicated that treatment with SAMe altered cell cycle kinetic S phase cell cycle arrest. Altogether, our data uncovered the evidence of the antiproliferative action of SAMe in liver cells, and SAMe could lead to cell cycle inhibition by up-regulating MCM3, MCM4 and E2F1 expression. It provided an important theoretical basis for the clinical chemoprevention and treatment in HCC of SAMe.

The vast majority of breast cancer death is a result of metastasis. Thus, accurate identification of patients who are likely to have metastasis is expected to improve survival. The G2M checkpoint plays a critical role in cell cycle. We hypothesized that breast cancer tumors with high activity of G2M pathway genes are more aggressive and likely to metastasize. To test this, we used the single-sample gene set variation analysis method to calculate the score for the Hallmark G2M checkpoint pathway using gene expression data of a total of 4626 samples from 12 human breast cancer cohorts. As expected, a high G2M pathway score correlated with enriched tumor expression of other cell proliferation-related gene sets. The score was significantly associated with clinical aggressive features of tumors and patient survival in estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Interestingly, a high G2M score of metastasis tumors was also significantly associated with worse survival. In primary as well as metastasis tumors with high scores, the infiltration of both pro- and anti-cancerous immune cells increased. Tumor G2M score was also associated with treatment response to systemic chemotherapy in ER-positive/HER2-negative cancer, and was predictive of response to cyclin-dependent kinase inhibition therapy.

Lung squamous cell carcinoma (LUSC) is one of the leading causes of tumor-driven deaths in the world. To date, studies on the tumor heterogeneity of LUSC at genomic level have only revealed limited therapeutic benefits. Therefore, system-wide research of LUSC at proteomic level may further improve precision medicine strategies on individual demands. To this end, we performed proteomic and phosphoproteomic study for LUSC samples of 25 Chinese patients. From our results, two subgroups (Cluster I and II) based on proteomic data were identified, which were associated with distinct molecular characteristics and clinicopathologic features. Combined with phosphoproteomic data, our result showed that spliceosome pathway was enriched in Cluster I, while focal adhesion pathway, immune-related pathways and Ras signaling pathway were enriched in Cluster II. In addition, we found that lymph node metastasis (LNM) was associated with our proteomic subgroups and cell cycle pathway was enriched in patients with LNM. Further analysis showed that MCM2, a DNA replication licensing factor involved in cell cycle pathway, was highly expressed in patients with poor prognosis, which was further proved by immunohistochemistry (IHC) analysis. In summary, our study provided a resource of the proteomic and phosphoproteomic features of LUSC in Chinese patients.

Background Pathway analysis is one of the later stage data analysis steps essential in interpreting high-throughput gene expression data. We propose a set of algorithms which given gene expression data can recognize which portion of sub-pathways are actively utilized in the biological system being studied. The degree of activation is measured by conditional probability of the input expression data based on the Bayesian Network model constructed from the topological pathway. Results We demonstrate the effectiveness of our pathway analysis method by conducting two case studies. The first one applies our method to a well-studied temporal microarray data set for the cell cycle using the KEGG Cell Cycle pathway. Our method closely reproduces the biological claims associated with the data sets, but unlike the original work ours can produce how pathway routes interact with each other above and beyond merely identifying which pathway routes are involved in the process. The second study applies the method to the p53 mutation microarray data to perform a comparative study. Conclusions We show that our method achieves comparable performance against all other pathway analysis systems included in this study in identifying p53 altered pathways. Our method could pave a new way of carrying out next generation pathway analysis.

Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant disease and has the worst prognosis and survival rate. TUBA1C is a microtubule component implicated in multiple cancers, however, the clinical significance and biological functions of TUBA1C in the progression of PDAC remain unexplored. Methods: The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis (GEPIA) data were employed to detect the TUBA1C mRNA expression and the relation between TUBA1C expression and overall survival (OS) in PDAC. Then, bioinformatic analysis was employed to determine the potential pathway and genes related to TUBA1C. Human pancreatic cancer tissue and adjacent non-tumor tissues samples were detected by immunochemistry (IHC) staining, and the correlation between TUBA1C expression and the clinicopathological features were investigated. Meanwhile, TUBA1C expression in PDAC cell lines was evaluated by western blotting. Furthermore, functional assays including cell viability, apoptosis, cell cycle, transwell assay, wound healing assay, and a xenograft tumor model were performed to determine the oncogenic role of TUBA1C in PDAC, respectively. Results: TUBA1C was overexpressed in the PDAC tissues and cells. IHC analysis showed that the TUBA1C overexpression was associated with short OS. Bioinformatic analysis indicated that TUBA1C overexpression was mainly associated with cell cycle regulation. The downregulation of TUBA1C significantly suppressed cell proliferation, induced cell apoptosis and cycle arrest, and inhibited invasion and migration in PDAC cells. Furthermore, TUBA1C downregulation also inhibited tumor growth in vivo. Conclusion: These findings suggested that TUBA1C downregulation suppressed PDAC aggressiveness via cell cycle pathway and that TUBA1C may serve as a potential prognostic marker for PDAC therapy.

Yan Jiao,1 Zhuo Fu,2 Yanqing Li,3 Lingyu Meng,1 Yahui Liu1 1Department of Hepatobiliary and Pancreatic Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, People’s Republic of China; 2Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, People’s Republic of China; 3Department of Pathophysiology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin 130021, People’s Republic of China Purpose: Liver cancer is a high mortality disease with no curable treatments. Posttranscriptional modifications play essential roles in the occurrence and the progression of liver cancer. EIF2B5 is a subunit of EIF2B that regulates the initiation and the rate of translation and participates in several diseases including tumors. This study aims to elucidate the prognostic significance of EIF2B5 in liver cancer. Materials and methods: We used The Cancer Genome Atlas database to analyze the expression of EIF2B5 in liver cancer. Then we used chi-squared and Fisher exact tests to test the correlation between clinical characteristics and EIF2B5 expression. Finally, we assessed the role of EIF2B5 in prognosis by Kaplan–Meier curves and Cox analysis. Gene set enrichment analysis was performed by using The Cancer Genome Atlas data set. Results: The results showed that EIF2B5 was upregulated in liver cancer, and the expressionwas related to histologic grade, clinical stage, and vital status. Moreover, Kaplan–Meier curves and Cox analysis implicated that highly expressed EIF2B5 correlated with poor prognosis, and EIF2B5 was an independent risk factor for liver cancer. Gene set enrichment analysis showed that ATR and BRCA pathway, cell cycle pathway, DNA repair, myc signaling pathway, and E2F targets are differentially enriched in EIF2B5 high-expression phenotype. Conclusion: Our results suggest that EIF2B5 participated in cancer progression and could become a biomarker for the prognosis of patients with liver cancer. Keywords: liver cancer, EIF2B5, prognosis, diagnosis

MicroRNAs (miRNAs), a group of small noncoding RNAs, are widely involved in the regulation of gene expression via binding to complementary sequences at 3'-untranslated regions (3'-UTRs) of target messenger RNAs. Recently, downregulation of miR-133b has been detected in various human malignancies. Here, the potential biological role of miR-133b in bladder cancer (BC) was investigated. In this study, we found the expression of miR-133b was markedly downregulated in BC tissues and cell lines (5637 and T24), and was correlated with poor overall survival. Notably, transgelin 2 (TAGLN2) was found to be widely upregulated in BC, and overexpression of TAGLN2 also significantly increased risks of advanced TMN stage. We further identified that upregulation of miR-133b inhibited glucose uptake, invasion, angiogenesis, colony formation and enhances gemcitabine chemosensitivity in BC cell lines by targeting TAGLN2. Additionally, we showed that miR-133b promoted the proliferation of BC cells, at least partially through a TAGLN2-mediated cell cycle pathway. Our results suggest a novel miR-133b/TAGLN2/cell cycle pathway axis controlling BC progression; a molecular mechanism which may offer a potential therapeutic target.

Background: Human paired box 2 (PAX2) plays a key role in cell fate, early patterning and organogenesis. Methods: We investigated the function of PAX2 on the biological behavior of endometrial cancer in vitro and in vivo and to explore the regulation mechanism, stable knocking-down and over-expression PAX2 endometrial cancer cell lines were established. CCK-8 and transwell assays were applied to determine proliferation, invasion and migration ability. Cell cycle distribution was analyzed by flow cytometry. Affymetrix GeneChip® human Exon 1.0 ST arrays was used to screen the downstream target genes of PAX2. Results: PAX2 significantly enhanced proliferation and invasiveness. In addition, PAX2 influenced the expression of cyclin-dependent kinase 1(CDK1), which play pivotal roles in cell cycle pathway. When CDK1 was knocked down, and the cell proliferation promotion role of PAX2 was attenuated dramatically to a level comparable with the control groups. Conclusions: PAX2, though influencing the expression of CDK1, promotes the proliferation, enhances the mobility of endometrial cancer cells, thus exerts an important role in the carcinogenesis of endometrial cancer. PAX2 may be a potential therapeutic target for endometrial cancer.

In this study, we aimed to investigate the effects of lncRNA CASC11 on gastric cancer (GC) cell progression through regulating miR-340-5p and cell cycle pathway. Expressions of lncRNA CASC11 in gastric cancer tissues and cell lines were determined by qRT-PCR. Differentially expressed lncRNAs, mRNAs and miRNAs were screened through microarray analysis. The relationship among CASC11, CDK1 and miR-340-5p was predicted by TargetScan and validated through dual luciferase reporter assay. Western blot assay examined the protein level of CDK1 and several cell cycle regulatory proteins. GO functional analysis and KEGG pathway analysis were used to predict the association between functions and related pathways. Cell proliferation was determined by CCK-8 assays. Cell apoptosis and cell cycle were detected by flow cytometry assay. CASC11 was highly expressed in GC tissues and cell lines. Knockdown of CASC11 inhibited GC cell proliferation, promoted cell apoptosis and blocked cell cycle. KEGG further indicated an enriched cell cycle pathway involving CDK1. QRT-PCR showed that miR-340-5p was down-regulated in GC cells tissues, while CDK1 was up-regulated. Furthermore, CASC11 acted as a sponge of miR-340-5p which directly targeted CDK1. Meanwhile, miR-340-5p overexpression promoted GC cell apoptosis and induced cell cycle arrest, while CDK1 overexpression inhibited cell apoptosis and accelerated cell cycle. Our study revealed the mechanism of CASC11/miR-340-5p/CDK1 network in GC cell line, and suggested that CASC11 was a novel facilitator that exerted a biological effect by activating the cell cycle signaling pathway. This finding provides a potential therapeutic target for GC.

Avian leukosis virus subgroup J (ALV-J), a highly oncogenic retrovirus, causes leukemia-like proliferative diseases in chickens. microRNAs post-transcriptionally suppress targets and are involved in the development of various tumors. We previously showed that miR-221 is upregulated in ALV-J-induced tumors. In this study, we analyzed the possible function of miR-221 in ALV-J tumorigenesis. The target validation system showed that CDKN1B is a target of miR-221 and is downregulated in ALV-J infection. As CDKN1B arrests the cell cycle and regulates its progression, we analyzed the proliferation of ALV-J-infected DF-1 cells. ALV-J-infection-induced DF1 cell derepression of G1/S transition and overproliferation required high miR-221 expression followed by CDKN1B downregulation. Cell cycle pathway analysis showed that ALV-J infection induced DF-1 cell overproliferation via the CDKN1B-CDK2/CDK6 pathway. Thus, miR-221 may play an important role in ALV-J-induced aggressive growth of DF-1 cells; these findings have expanded our insights into the mechanism underlying ALV-J infection and tumorigenesis.

Zearalenone (ZEA) was a mycotoxin biosynthesized by a variety of Fusarium fungi via a polypeptide pathway. ZEA has significant toxic reaction on immune cells. Thymic epithelial cells (TECs) as a crucial constituent of thymic stroma can provide unique microenvironment for thymocyte maturation, but the mechanism of ZEA affecting the TECs is poorly understood. The basic data about gene expression differences for the ZEA on thymic epithelial cell line 1 (MTEC1) will help us to elucidate this mechanism. Here, cell viability and proliferation assay and transcriptome sequencing on MTEC1 treated with ZEA were performed. 4188 differentially expressed genes (DEGs) between ZEA treated and control groups were identified, confirmed and analyzed. Our results showed that 10-50μg/ml ZEA significantly inhibited MTEC1 proliferation and arrested cell cycle at G2/M phase. Gene ontology and KEGG pathway analysis revealed that Chemokine, JAK-STAT and Toll-like receptor signaling pathway, were involved in the cell cycle pathway. 16 key genes involved in the cell cycle processes were validated and the results suggested that Mitotic catastrophe (MC) may take part in ZEA inhibition of METC1 cell proliferation. These data highlighted the importance of cell cycle pathway in MTEC1 treated with ZEA, and will contribute to get the molecular mechanisms of ZEA inhibition of MTEC1 cell proliferation.

Background/Aims: Liver cancer has the second highest cancer-related death rate globally and has relatively few targeted therapeutics. Polo-like kinase 1 (PLK1) is a fascinating trigger of the cell cycle; however, the still-rudimentary understanding of PLK1 at present is a significant barrier to its clinical applications. Here, we comprehensively clarified the clinicopathological value and potential functions of PLK1 in hepatocellular carcinoma (HCC). Methods: HCC-related microarrays, RNA-sequencing datasets and published studies were deeply mined and integrated from The Cancer Genome Atlas, Gene Expression Omnibus, ArrayExpress, Oncomine, literature databases, and immunohistochemistry experiments. Meanwhile, the associations between PLK1 expression and its clinicopathological implications and prognostic value in HCC patients were assessed. The standardized mean difference, summary receiver operating characteristic curve and the corresponding area under the curve, hazard ratios, odds ratios (ORs), and their 95% confidence intervals (CIs) were examined by STATA 12.0. Additionally, several bioinformatics methods were used to identify the potential function of PLK1 in HCC. Results: Comprehensive analyses revealed that PLK1 was significantly increased in HCC (standardized mean difference = 1.34, 95% CI: 1.03–1.65, P < 0.001). The results of diagnostic tests specified that in the summary receiver operating characteristic curve, the area under the curve was 0.88 (95% CI: 0.85–0.90). Furthermore, an elevated PLK1 level significantly predicted unfavorable overall survival (hazard ratio = 1.78, 95% CI: 1.10–2.88, P = 0.019) and was correlated with female gender (OR = 0.73, 95% CI: 0.56–0.95, P = 0.017), tumor thrombus (OR = 3.97, 95% CI: 1.46–10.78, P < 0.001), metastasis (OR = 3.46, 95% CI: 1.33–9.01, P = 0.011), pathologic stage (OR = 1.56, 95% CI: 1.17–2.07, P = 0.002), Barcelona Clinic Liver Cancer stage (OR = 5.76, 95% CI: 2.17–15.28, P < 0.001) and histologic grade (OR = 2.33, 95% CI: 1.12–487, P = 0.024). Through bioinformatics methods, we determined that enhancing the proliferative effect of PLK1 in HCC was associated with a series of hub genes and the activation of the cell cycle pathway. Conclusions: These findings substantiated that PLK1 may be an independent prognostic biomarker in HCC and may facilitate the development of targeted precision oncology.