Reduced expression of PinX1 correlates to progressive features in patients with prostate cancer

PinX1 plays multifaceted roles in human cancers: a review and perspectives

BACKGROUND

Pin2/TRF1 interacting protein X1 (PinX1), a telomerase inhibitor, is located at human chromosome 8p23. This region is important for telomere length maintenance and chromosome stability, both of which are essential for regulating human ageing and associated diseases.

METHODS AND RESULTS

We investigated the research progress of PinX1 in human cancers. In cancers, the expression levels of PinX1 mRNA and protein vary according to cancer cell types, and PinX1 plays a critical role in the regulation of cancer development and progression. Additionally, a review of the literature indicates that PinX1 is involved in mitosis and affects the sensitivity of cancer cells to radiation-induced DNA damage. Therefore, PinX1 has therapeutic potential for cancer, and understanding the function of PinX1 in the regulation of cancers is crucial for improving treatment. In this review, we discuss the expression level of PinX1 in a variety of cancers and how it affects the implicated pathways. Additionally, we outline the function of PinX1 in cancer cells and provide a theoretical basis for PinX1-related cancer therapy.

CONCLUSIONS

PinX1 has promising prospects in future cancer therapeutics. This review may provide theoretical support for researchers in this field.

Different Approaches for the Profiling of Cancer Pathway-Related Genes in Glioblastoma Cells

Deregulation of signalling pathways that regulate cell growth, survival, metabolism, and migration can frequently lead to the progression of cancer. Brain tumours are a large group of malignancies characterised by inter- and intratumoral heterogeneity, with glioblastoma (GBM) being the most aggressive and fatal. The present study aimed to characterise the expression of cancer pathway-related genes (n = 84) in glial tumour cell lines (A172, SW1088, and T98G). The transcriptomic data obtained by the qRT-PCR method were compared to different control groups, and the most appropriate control for subsequent interpretation of the obtained results was chosen. We analysed three widely used control groups (non-glioma cells) in glioblastoma research: Human Dermal Fibroblasts (HDFa), Normal Human Astrocytes (NHA), and commercially available mRNAs extracted from healthy human brain tissues (hRNA). The gene expression profiles of individual glioblastoma cell lines may vary due to the selection of a different control group to correlate with. Moreover, we present the original multicriterial decision making (MCDM) for the possible characterization of gene expression profiles. We observed deregulation of 75 genes out of 78 tested in the A172 cell line, while T98G and SW1088 cells exhibited changes in 72 genes. By comparing the delta cycle threshold value of the tumour groups to the mean value of the three controls, only changes in the expression of 26 genes belonging to the following pathways were identified: angiogenesis FGF2; apoptosis APAF1, CFLAR, XIAP; cellular senescence BM1, ETS2, IGFBP5, IGFBP7, SOD1, TBX2; DNA damage and repair ERCC5, PPP1R15A; epithelial to mesenchymal transition SNAI3, SOX10; hypoxia ADM, ARNT, LDHA; metabolism ATP5A1, COX5A, CPT2, PFKL, UQCRFS1; telomeres and telomerase PINX1, TINF2, TNKS, and TNKS2. We identified a human astrocyte cell line and normal human brain tissue as the appropriate control group for an in vitro model, despite the small sample size. A different method of assessing gene expression levels produced the same disparities, highlighting the need for caution when interpreting the accuracy of tumorigenesis markers.

PINX1 promotes malignant transformation of thyroid cancer through the activation of the AKT/MAPK/β-catenin signaling pathway

Although thyroid cancer is the most prevalent endocrine malignancy, overall patients with thyroid cancer have a good long-term survival. However, a small percentage of patients with progressive thyroid cancer have poor outcomes, and the genetic drivers playing a key role thyroid cancer progression are mostly unknown. Here, we investigated the role of the PINX1 in thyroid cancer progression. Interestingly, PINX1 expression was significantly higher in ATC than in PTC in both patients and cell lines. When PINX1 was knockdown in ATC cells, cell proliferation rates, colony formation capacity, and cell cycle progression were significantly reduced. Furthermore, cell motility and the expression of EMT drivers were reduced by PINX1 downregulation. In contrast, the overexpression of PINX1 in PTC cells significantly increased those phenotypes of tumor progression, which demonstrates that PINX1 could promote tumor proliferation and malignant transformation in both PTC and ATC cells. To further understand whether PINX1 is also involved in the progression of PTC to ATC, we examined PI3K/AKT, MAPK, and β-catenin signaling activation after PINX1 modulation. Decreased PINX1 expression reduced the levels of p-AKT, p-ERK, p-p38, and β-catenin in ATC cells, but the increase of PINX1 expression upregulated the phosphorylation of AKT, ERK, and p38 and the levels of β-catenin in PTC cells. These results were all confirmed in xenograft mouse tumors. Our findings suggest that PINX1 regulates thyroid cancer progression by promoting cell proliferation, EMT, and signaling activation, and support the hypothesis that PINX1 could be a prognostic marker and a therapeutic target of thyroid cancer.

Prognostic value of TERF1 expression in prostate cancer

BACKGROUND

Telomere dysfunction is one of the hallmarks of cancer and is crucial to prostate carcinogenesis. TERF1 is a gene essential to telomere maintenance, and its dysfunction has already been associates with several cancers. TERF1 is a target of miR-155, and this microRNA can inhibit its expression and promotes carcinogenesis in breast cancer. We aim to analyze TERF1, in gene and mRNA level, involvement in prostate cancer progression.

RESULTS

Alterations in TERF1 DNA were evaluated using datasets of primary tumor and castration-resistant tumors (CRPC) deposited in cBioportal. The expression of TERF1 mRNA levels was assessed utilizing TCGA datasets, clinical specimens, and metastatic prostate cancer cell lines (LNCaP, DU145, and PC3). Six percent of localized prostate cancer presents alterations in TERF1 (the majority of that was amplifications). In the CRPC cohort, 26% of samples had TERF1 amplification. Patients with TERF1 alterations had the worst overall survival only on localized cancer cohort (p = 0.0027). In the TCGA cohort, mRNA levels of TERF1 were downregulated in comparison with normal tissue (p = 0.0013) and upregulated in tumors that invade lymph nodes (p = 0.0059). The upregulation of TERF1 is also associated with worst overall survival (p = 0.0028) and disease-free survival (p = 0.0023). There is a positive correlation between TERF1 and androgen receptor expression in cancer tissue (r = 0.53, p < 0.00001) but not on normal tissue (r = - 0.16, p = 0.12). In the clinical specimens, there is no detectable expression of TERF1 and upregulation of miR-155 (p = 0.0348). In cell lines, TERF1 expression was higher in LNCaP and was progressively lower in DU145 and PC3 (p = 0.0327) with no differences in miR-155 expression.

CONCLUSION

Amplification/upregulation of TERF1 was associated with the worst prognostic in localized prostate cancer. Our results corroborate that miR-155 regulates TERF1 expression in prostate cancer. TERF1 has the potential to become a biomarker in prostate cancer.

Oncogenic role of PinX1 in prostate cancer cells through androgen receptor dependent and independent mechanisms

Coregulators play an important role in prostate cancer (PCa), modulating androgen receptor (AR) action and representing a possible cause of androgen deprivation therapy failure. Pin2-interacting protein X1 (PinX1) is a nucleolar protein described as a steroid hormone receptor coregulator in breast cancer cell lines. In this work, we studied the effect of PinX1 on AR action in PCa. Our results demonstrate that PinX1 acts as an AR coactivator, increasing its transcriptional activity and target gene expression, as well as proliferation, migration and colony formation in PCa cell lines. These effects are observed in the presence and absence of AR agonist and antagonists, suggesting a possible androgen independent pathway for PinX1. We present the first oncogenic roles described for PinX1, acting as a coactivator of the AR.

MicroRNA-501-5p Targets PINX1 Gene to Regulate the Proliferation, Migration, and Invasion of Prostatic Carcinoma Cells

The expression of PINX1 is decreased in prostate cancer, and the high level of miRNA-501-5p promotes the proliferation of liver cancer cells. However, there is no relevant research on miRNA-501-5p in prostate cancer. miRNA-501-5p can target the 3’UTR of PINX1 mRNA; however, it is unclear whether they affect the migration, invasion, and proliferation of prostate cancer cells. In this paper, PCR and Western blot were used to detect the expression of miRNA-501-5p and PINX1 in prostate cancer cells PC3, LNCaP, and DU145, and normal prostate epithelial cells RWPE-1. Compared to the normal prostate epithelial cells, miRNA-501-5p expression in prostate cancer cells was increased, and the expression of PINX1 was decreased. The methyl thiazolyl tetrazolium assay was used to detect the migration, proliferation, and invasion of prostate cancer DU145 cells. It was found that suppressing the expression of miRNA-501-5p or overexpressing PINX1 could inhibit the proliferation and other biological behaviors of DU145 cells; at the same time, the level of Cyclin D1, MMP-2, and MMP-14 protein was decreased, and the protein level of P21 was increased. Moreover, inhibition of PINX1 expression could partially reverse miRNA-501-5p’s inhibitory effect on the migration, invasion, and proliferation of prostate cancer cells. Therefore, miRNA-501-5p targeted PINX1 for down-regulation to promote prostate cancer cell migration, invasion, and proliferation.

Insufficient PINX1 expression stimulates telomerase activation by direct inhibition of EBV LMP1-NF-κB axis during nasopharyngeal carcinoma development

OBJECTIVE

Early malignant transformation of nasopharyngeal carcinoma(NPC) is associated with Epstein-Barr virus(EBV) infection and telomerase activation. The EBV latent membrane protein 1(LMP1) regulates expression of various genes by triggering NF-κB signaling pathway. PINX1 is a well-identified tumor suppressor gene by inhibiting telomerase activity and cancer cell growth. However, whether and how EBV inhibit PINX1 expression and activate telomerase in NPC is still incompletely elucidated.

METHODS

Immunohistochemistry, real-time PCR and Western blotting were utilized to explore the expression of PINX1. Chromatin immunoprecipitation(ChIP) and Dual-luciferase reporter assay were used to elucidate the regulatory mechanism between NF-κB and PINX1. TRAP-SYBR Green assay and Southern blotting were utilized to detect telomerase activity and telomere length. CCK8 and EdU tests were conducted to measure proliferation ability.

RESULTS

We demonstrated that PINX1 is down-regulated in NPC for the first time. Mechanistically, we found that LMP1 could inhibit the transcriptional activity of PINX1 by promoting the binding of p65 to three specific sites in PINX1 promoter, significantly, two(-1698/-1689, tgcaatttcc; -206/-197, cgggctttac) of which have not been reported. In addition, we also observed that LMP1 overexpression resulted in increased telomerase activity, prolonged telomere length and enhanced proliferation.

CONCLUSION

We first discovered EBV led to reduced PINX1 expression through LMP1-NF-κB-PINX1 axis, which up-regulated telomerase activity in NPC. And hence, the tumor cells acquired the ability to proliferate more exuberantly. This signaling pathway illustrates the relationship between EBV latent infection and telomerase activation, and further provides new thinking for early diagnosis and treatment in NPC.

Prognostic and Clinicopathological Value of PINX1 in Various Human Tumors: A Meta-Analysis

PINX1 (Pin2/TRF1 interacting protein X1, an intrinsic telomerase inhibitor and putative tumor suppressor gene) may represent a novel prognostic tumor biomarker. However, the results of previous studies are inconsistent and the prognostic value of PINX1 remains controversial. Therefore, we conducted a meta-analysis to determine whether PINX1 expression is associated with overall survival (OS), disease-specific survival (DSS), disease-free survival (DFS), recurrence-free survival (RFS), and clinicopathological characteristics in patients with malignant tumors. A systematic search was performed in the PubMed, Web of Science, and Embase databases in April 2018. Quality assessment was performed according to the modified Newcastle-Ottawa Scale. Pooled odds ratios (ORs) and hazard ratios (HRs) with 95.0% confidence intervals (CIs) were calculated to determine the relationship between PINX1 expression and OS, DSS, DFS/RFS, and clinicopathological characteristics. Due to the heterogeneity across the included studies, subgroup and sensitivity analyses were performed. Fixed-effects models were used when the heterogeneity was not significant and random-effects models were used when the heterogeneity was significant. Fourteen studies of 16 cohorts including 2,624 patients were enrolled. Low PINX1 expression was associated with poor OS (HR: 1.51, 95.0% CI: 1.03-2.20; P = 0.035) and DFS/RFS (HR: 1.78, 95.0% CI: 1.28-2.47; P = 0.001) but not DSS (HR: 0.80, 95.0% CI: 0.38-1.67; P = 0.548). Low PINX1 expression was also associated with lymphatic invasion (OR: 2.23, 95.0% CI: 1.35-3.70; P = 0.002) and advanced tumor-node-metastasis stage (OR: 2.43, 95.0% CI: 1.29-4.57; P = 0.006). No significant associations were observed between low PINX1 expression and sex, depth of invasion, grade of differentiation, and distant metastasis. Low PINX1 expression was associated with poor OS and DFS/RFS and lymphatic invasion and advanced tumor-node-metastasis stage, suggesting that PINX1 expression may be a useful predictor of prognosis in patients with malignant tumors.

The clinical significance of PINX1 expression in papillary thyroid carcinoma

PIN2/TERF1 interacting telomerase inhibitor 1 (PINX1) is a telomerase inhibitor located on human chromosome 8p23 and also acts as a tumor suppressor in several types of cancers, including breast, gastric, ovarian, and bladder cancer. However, the role of PINX1 expression in papillary thyroid carcinoma (PTC) has not been defined. Therefore, we investigated the role of PINX1 expression in PTC by analyzing the correlation between PINX1 expression and various clinicopathological factors. Immunohistochemistry for PINX1 was performed using a tissue microarray of samples taken from the 160 patients with PTC. We also assessed mRNA and protein expression for PINX1 via quantitative real-time polymerase chain reaction and immunohistochemical analysis. Positive staining for PINX1 was found in 16.3% of PTC cases. PINX1 expression was significantly associated with tumor size, lymph node metastasis, telomerase reverse transcriptase, promoter mutation and recurrence. PINX1 mRNA expression was more pronounced in the recurrent group than in the nonrecurrent group. In addition, results of the binary logistic regression model showed that PINX1 protein expression had a significant influence on recurrence. We concluded that PINX1 expression was associated with several clinicopathological factors and had a significant influence on recurrence in patients with PTC. Therefore, PINX1 expression could be a useful prognostic marker in PTC patients.

PinX1: structure, regulation and its functions in cancer

PIN2/TRF1-interacting telomerase inhibitor 1 (PinX1) is a novel cloned gene located at human chromosome 8p23, playing a vital role in maintaining telomeres length and chromosome stability. It has been demonstrated to be involved in tumor genesis and progression in most malignancies. However, some researches showed opposing molecular status of PinX1 gene and its expression patterns in several other types of tumors. The pathogenic mechanism of PinX1 expression in human malignancy is not yet clear. Moreover, emerging evidence suggest that PinX1 (especially its TID domain) might be a potential new target cancer treatment. Therefore, PinX1 may be a new potential diagnostic biomarker and therapeutic target for human cancers, and may play different roles in different human cancers. The functions and the mechanisms of PinX1 in various human cancers remain unclear, suggesting the necessity of further extensive works of its role in tumor genesis and progression.

Identifying the biomarker potential of telomerase activity and shelterin complex molecule, telomeric repeat binding factor 2 (TERF2), in multiple myeloma

Telomere length (TL) is maintained by telomere capping protein complex called shelterin complex. We studied the possible involvement and biomarker potential of shelterin complex molecules in naive multiple myeloma (MM) patients and controls. TL, relative telomerase activity (RTA), real-time PCR and Western blotting were performed in bonemarrow sample of 70 study subjects (patients = 50; controls = 20). Significantly lowered mean TL, increased RTA and higher mRNA expression of shelterin molecules were observed in patients, while PIN2/TERF1 interacting telomerase inhibitor 1 (PINX1) showed lower mRNA expression. Significantly increased protein expression of telomeric repeat binding factor 2 (TERF2), protection of telomeres 1, adrenocortical dysplasia homolog, Tankyrase 1 and telomere reverse transcriptase were observed in MM patients. Significant correlation was observed among genes and of genes with clinical parameters. In conclusion, our findings showed alteration of these molecules at mRNA and protein levels suggested their involvement in disease progression. Optimal sensitivity and specificity of TERF2 and RTA on receiver operating characteristics curve analysis and univariate analysis demonstrated their biomarkers potential in better prediction of disease course.

NF-κB potentiates tumor growth by suppressing a novel target LPTS

Background

Chronic inflammation is causally linked to the carcinogenesis and progression of most solid tumors. LPTS is a well-identified tumor suppressor by inhibiting telomerase activity and cancer cell growth. However, whether and how LPTS is regulated by inflammation signaling is still incompletely elucidated.

Methods

Real-time PCR and western blotting were used to determine the expression of p65 and LPTS. Reporter gene assay, electrophoretic mobility shift assay and chromatin immunoprecipitation were performed to decipher the regulatory mechanism between p65 and LPTS. Cell counting kit-8 assays and xenograt models were used to detect p65-LPTS-regulated cancer cell growth in vitro and in vivo, respectively.

Results

Here we for the first time demonstrated that NF-κB could inhibit LPTS expression in the mRNA and protein levels in multiple cancer cells (e.g. cervical cancer and colon cancer cells). Mechanistically, NF-κB p65 could bind to two consensus response elements locating at −1143/−1136 and −888/−881 in the promoter region of human LPTS gene according to EMSA and ChIP assays. Mutation of those two binding sites rescued p65-suppressed LPTS promoter activity. Functionally, NF-κB regulated LPTS-dependent cell growth of cervical and colon cancers in vitro and in xenograft models. In translation studies, we verified that increased p65 expression was associated with decreased LPTS level in multiple solid cancers.

Conclusions

Taken together, we revealed that NF-κB p65 potentiated tumor growth via suppressing a novel target LPTS. Modulation of NF-κB-LPTS axis represented a potential strategy for treatment of those inflammation-associated malignancies.

PinX1 Is a Potential Prognostic Factor for Non-Small-Cell Lung Cancer and Inhibits Cell Proliferation and Migration

PinX1 has been identified as a suppressor of telomerase enzymatic activity. However, the tumour-suppressive roles of PinX1 in different types of human cancers are unclear. PinX1 expression status and its correlation with clinicopathological features in non-small-cell lung cancer (NSCLC) have not been investigated. Accordingly, in this study, we aimed to evaluate the roles of PinX1 in NSCLC. PinX1 expression status was examined by immunohistochemistry using tissue microarray from a total of 158 patients. Correlations among PinX1 expression, clinicopathological variables, and patient survival were analysed. Furthermore, we overexpressed PinX1 in NSCLC cells and tested telomerase activity using real-time quantitative telomeric repeat amplification protocol (qTRAP) assays. Proliferation and migration of NSCLC cells were examined using the MTS method, wound healing assays, and transwell assays, respectively. Our results showed that negative PinX1 expression was associated with a poor prognosis in NSCLC. Sex, smoking status, lymph gland status, subcarinal lymph node status, pathological stage, and PinX1 expression were related to survival. PinX1 was not an independent prognostic factor in NSCLC. PinX1 overexpression inhibited proliferation and migration in NSCLC cells by suppressing telomerase activity. Our findings suggested that PinX1 could be a potential tumour suppressor in NSCLC and that loss of PinX1 promoted NSCLC progression.

Low expression of PinX1 is associated with malignant behavior in basal-like breast cancer

Human Pinx1 protein, associated with shelterin proteins, is widely revealed as a haploinsufficient tumor suppressor. Growing evidence has manifested the deregulation of PinX1 in distinct cancers. Nonetheless, the loss status of PinX1 and its diagnostic, prognostic and clinicopathological significance in Basal-like breast cancer are still unclear. In the present study, the PinX1 expression levels of breast cancer tissues were investigated by qRT-PCR and immunoblotting assays. Then immunohistochemistry (IHC) was performed to detect PinX1 expression on a tissue microarray. The optimal threshold for PinX1 positivity was determined by receiver operating characteristic (ROC) curve analysis. To clarify the probable role of PinX1 in BLBC, the PinX1 knockout and stably over-expressed MDA-MB-231 cell lines were constructed by the CRISPR-Cas9 system and gene transfection. The association of PinX1 expression with cell proliferation, migration and apoptosis of MDA-MB-231 cells were observed by CCK-8 assay, wound healing assay, Transwell assay, flow cytometric analysis and immunoblotting of the cleaved caspase-3 protein level. Our results showed that both PinX1 mRNA and protein expression were downregulated in breast cancer tissues (P<0.05). In IHC analysis, the optimal cut-off parameter for PinX1 positive expression was 62.5% (the AUC was 0.749, P<0.01). PinX1 positivity was 76.9% (10/14) in luminal subtypes, 50% (5/10) in Her2-enriched breast cancer and 27.3% (9/33) in basal-like subtypes. Besides, in 59 invasive ductal breast carcinomas, PinX1 expression was inversely related to histology grade (P<0.05) while it was positively associated with PR status (P<0.05) and ER status (P<0.05). These results indicated that low expression of PinX1 correlated with aggressive clinicopathological significance of breast cancer, especially in the basal-like subtype. Besides, we identified that overexpression of PinX1 inhibited the proliferation rates and migration ability and increased the apoptosis rates of BLBC. Our findings demonstrated that low expression of PinX1 was associated with malignant behaviors in basal-like subtype of breast cancer. PinX1 is likely a feasible biomarker and molecular target of BLBC.

Hepatitis B virus X protein promotes hepatocellular carcinoma invasion and metastasis via upregulating thioredoxin interacting protein

Hepatitis B virus X protein (HBx), a multifunctional protein encoded by the X gene of the hepatitis B virus (HBV) is involved in the metastasis of HBV-associated hepatocellular carcinoma (HCC) through various pathways, including upregulating intracellular reactive oxygen species (ROS). Thioredoxin interacting protein (TXNIP) is a key mediator of intracellular ROS, but its function in HBx-mediated metastasis of HBV-associated HCC is elusive. In the present study, HBV-associated HCC tissues with or without metastasis and HepG2 cells were used to study the function of TXNIP in HBx-mediated metastasis of HBV-associated HCC. Initially, the expression levels of TXNIP and HBx in HBV-associated HCC tissues were detected by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction. The results revealed that high expression of TXNIP may be an independent risk factor for metastasis of HBV-associated HCC, and the mRNA levels of TXNIP and HBx were positively associated. Secondly, the association between HBx and TXNIP was investigated using a HBx expression stable cell line, in which HBx expression was induced and controlled by doxycycline. The results demonstrated that HBx may upregulate TXNIP expression in HepG2 cells. Thirdly, the effects of TXNIP and HBx on HepG2 cell migration and invasion were studied by scratch and Matrigel invasion assays, respectively. The results demonstrated that TXNIP overexpression enhanced HepG2 cell migration and invasion. In addition, ectopic expression of HBx promoted HepG2 cell migration and invasion, and this effect may be attenuated by knockdown of TXNIP expression, which indicated that TXNIP may be involved in the process. In summary, the present results demonstrated that TXNIP may be involved in HBx-mediated metastasis of HBV-associated HCC.

The depletion of PinX1 involved in the tumorigenesis of non-small cell lung cancer promotes cell proliferation via p15/cyclin D1 pathway

Background

The telomerase/telomere interacting protein PinX1 has been suggested as a tumor suppressor. However, the clinical and biological significance of PinX1 in human non-small cell lung cancer (NSCLC) is unclear.

Methods

PinX1 gene/expression pattern and its association with NSCLC patient survival were analyzed in cBioportal Web resource and two cohorts of NSCLC samples. A series of in vivo and in vitro assays were performed to elucidate the function of PinX1 on NSCLC cells proliferation and underlying mechanisms.

Results

More frequency of gene PinX1 homozygous deletion and heterozygote deficiency was first retrieved from cBioportal Web resource. Low expression of PinX1 correlated with smoking condition, histological type, T stage, N stage, M stage and TNM stage, and was an independent predictor for overall survival in a learning cohort (n = 93) and a validation cohort (n = 51) of NSCLC patients. Furthermore, knockdown of PinX1 dramatically accelerated NSCLC cell proliferation and G1/S transition, whereas ectopic overexpression of PinX1 substantially inhibited cell viability and cell cycle transition in vitro and in vivo. p15/cyclin D1 pathway and BMP5 might contribute to PinX1-associated cell proliferation and cell cycle transition.

Conclusion

The cost-effective expression of PinX1 could constitute a novel molecular predictor/marker for NSCLC management.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0637-4) contains supplementary material, which is available to authorized users.

Enterovirus 71 3C Promotes Apoptosis through Cleavage of PinX1, a Telomere Binding Protein

Enterovirus 71 (EV71) is an emerging pathogen causing hand, foot, and mouth disease (HFMD) and fatal neurological diseases in infants and young children due to their underdeveloped immunocompetence. EV71 infection can induce cellular apoptosis through a variety of pathways, which promotes EV71 release. The viral protease 3C plays an important role in EV71-induced apoptosis. However, the molecular mechanism responsible for 3C-triggered apoptosis remains elusive. Here, we found that EV71 3C directly interacted with PinX1, a telomere binding protein. Furthermore, 3C cleaved PinX1 at the site of Q50-G51 pair through its protease activity. Overexpression of PinX1 reduced the level of EV71-induced apoptosis and EV71 release, whereas depletion of PinX1 by small interfering RNA promoted apoptosis induced by etoposide and increased EV71 release. Taken together, our study uncovered a mechanism that EV71 utilizes to promote host cell apoptosis through cleavage of cellular protein PinX1 by 3C.

IMPORTANCE

EV71 3C plays an important role in processing viral proteins and interacting with host cells. In this study, we showed that 3C promoted apoptosis through cleaving PinX1, a telomere binding protein, and that this cleavage facilitated EV71 release. Our study demonstrated that PinX1 plays an important role in EV71 release and revealed a novel mechanism that EV71 utilizes to induce apoptosis. This finding is important in understanding EV71-host cell interactions and has potential impact on understanding other enterovirus-host cell interactions.

TAGLN2, a novel regulator involved in Hepatitis B virus transcription and replication

Hepatitis B virus (HBV) infection is one of the major health problems in the world. Transgelin-2 (TAGLN2) expression has been revealed to be significantly altered in previous studies concerning HBV-host interaction. The present study investigated TAGLN2 expression patterns in HBV related hepatocellular carcinoma (HCC) tissues and its role in HBV transcription and replication. We collected 59 HBV related HCC tissue samples, their adjacent non-tumoral tissues and 16 normal livers to make the tissue microarray. TAGLN2 protein was detected by immunohistochemistry and the transcriptional levels of TAGLN2, HBc, HBs and HBx were detected by qRT-PCR. Then we investigated the function of TAGLN2 on HBV transcription and replication in vitro by ectopic expressing or knocking down TAGLN2 in HepG2 and HepG2.2.15 cell lines. We further studied the effect of HBx on TAGLN2 expression with a Tet-on HBx expressing cell line. TAGLN2 protein expression was lower in normal livers and HBV-HCC tissues comparing to adjacent non-tumoral tissues. The transcriptional levels of TAGLN2 in HBV-HCC tissues and their adjacent tissues were positively related to that of HBc, HBs and HBx (P < 0.05). Ectopic expression of TAGLN2 in vitro could enhance HBV transcription and replication while suppressing TAGLN2 had the contrary effect. TAGLN2 could be induced by HBx in a dose-dependent manner. Our data demonstrated that TAGLN2 might be an HBx induced positive host factor involved in HBV transcription and replication and HBx related liver fibrosis and tumorigenesis.

PinX1 serves as a potential prognostic indicator for clear cell renal cell carcinoma and inhibits its invasion and metastasis by suppressing MMP-2 via NF-κB-dependent transcription

PIN2/TRF1-interacting telomerase inhibitor 1 (PinX1) is a novel cloned gene which has been identified as a major haploinsufficient tumor suppressor essential for maintaining telomerase activity, the length of telomerase and chromosome stability. This study explored the clinical significance and biological function of PinX1 in human clear cell renal cell carcinoma (ccRCC). The clinical relevance of PinX1 in ccRCC was evaluated using tissue microarray and immunohistochemical staining in two independent human ccRCC cohorts. Our data demonstrated that PinX1 expression was dramatically decreased in ccRCC tissues compared with normal renal tissues and paired adjacent non-tumor tissues. Low PinX1 expression was significantly correlated with depth of invasion, lymph node metastasis and advanced TNM stage in patients, as well as with worse overall and disease-specific survival. Cox regression analysis revealed that PinX1 expression was an independent prognostic factor for ccRCC patients. Moreover, PinX1 inhibited the migration and invasion of ccRCC by suppressing MMP-2 expression and activity via NF-κB-dependent transcription in vitro. In vivo studies confirmed that PinX1 negatively regulated ccRCC metastasis and the expression of MMP-2 and NF-κB-p65. These findings indicate that PinX1 suppresses ccRCC metastasis and may serve as a ccRCC candidate clinical prognostic marker and a potential therapeutic target.

Novel role for PINX1 as a coregulator of nuclear hormone receptors

Estrogen receptor alpha (ERα) has an established role in breast cancer biology. Transcriptional activation by ERα is a multistep process influenced by coactivator and corepressor proteins. This work shows that Pin2 interacting protein 1 (PINX1) interacts with the N-terminal domain of ERα and functions as a corepressor of ERα. Furthermore, it represses both AF-1 and AF-2 transcriptional activities. Chromatin immunoprecipitation assays verified that the interaction between ERα and PINX1 occurs on E2 regulated promoters and enhanced expression of PINX1 deregulates the expression of a number of genes that have a role in cell growth and proliferation in breast cancer. PINX1 overexpression decreases estrogen mediated proliferation of breast cancer cell lines, while its depletion shows the opposite effect. Taken together, these data show a novel molecular mechanism for PINX1 as an attenuator of estrogen receptor activity in breast cancer cell lines, furthering its role as a tumor suppressor gene in breast cancer.

Reduced expression of sushi domain containing 2 is associated with progression of non-small cell lung cancer

Sushi domain containing 2 (SUSD2) has been identified as a gene encoding an 822-amino acid protein, which contains a transmembrane domain and functional domains inherent to adhesion molecules. Previous studies have reported that increased expression of SUSD2 has a critical role in tumorigenesis in human breast cancer. However, to the best of our knowledge, SUSD2 expression status and its correlation with the clinicopathological features of non-small cell lung cancer (NSCLC) have not previously been investigated. In the present study, reverse transcription-quantitative polymerase chain reaction and western blotting were used to evaluate SUSD2 messenger RNA (mRNA) and protein expression in NSCLC and adjacent normal lung tissues. The clinicopathological significance of SUSD2 was investigated by immunohistochemical analysis of an NSCLC tissue microarray. Receiver operating characteristic analysis was used to determine the cut-off score for positive expression of SUSD2. Furthermore, the correlation between SUSD2 expression and the clinicopathological features of NSCLC was analyzed by χ² test. The results revealed that SUSD2 mRNA (P<0.0001) and protein (P<0.0001) expression levels were significantly decreased in NSCLC tissues compared with those of adjacent normal tissues. When the SUSD2 positive expression percentage was determined to be >47.5% (area under ROC curve, 0.799; P<0.000), positive expression of SUSD2 was observed in 100% (32/32) of normal lung tissues and 55% (88/160) of NSCLC tissues by immunohistochemistry (χ²=21.160; P<0.000). Furthermore, it was demonstrated that the reduced SUSD2 protein levels in cancer tissues were positively correlated with poor histological grade (χ²=41.764; P<0.000), advanced clinical stage (χ²=10.790; P=0.013), higher pT (χ²=9.070; P=0.028) and positive regional lymph node metastasis (χ²=15.399; P=0.002). In conclusion, these data suggest that the reduced expression of SUSD2 is associated with the progression of NSCLC and may have a role in the pathogenesis of NSCLC.

Consensus reference gene(s) for gene expression studies in human cancers: end of the tunnel visible?

BACKGROUND

Gene expression studies are increasingly used to provide valuable information on the diagnosis and prognosis of human cancers. Also, for in vitro and in vivo experimental cancer models gene expression studies are widely used. The complex algorithms of differential gene expression analyses require normalization of data against a reference or normalizer gene, or a set of such genes. For this purpose, mostly invariant housekeeping genes are used. Unfortunately, however, there are no consensus (housekeeping) genes that serve as reference or normalizer for different human cancers. In fact, scientists have employed a wide range of reference genes across different types of cancer for normalization of gene expression data. As a consequence, comparisons of these data and/or data harmonizations are difficult to perform and challenging. In addition, an inadequate choice for a reference gene may obscure genuine changes and/or result in erroneous gene expression data comparisons.

METHODS

In our effort to highlight the importance of selecting the most appropriate reference gene(s), we have screened the literature for gene expression studies published since the turn of the century on thirteen of the most prevalent human cancers worldwide.

CONCLUSIONS

Based on the analysis of the data at hand, we firstly recommend that in each study the suitability of candidate reference gene(s) should carefully be evaluated in order to yield reliable differential gene expression data. Secondly, we recommend that a combination of PPIA and either GAPDH, ACTB, HPRT and TBP, or appropriate combinations of two or three of these genes, should be employed in future studies, to ensure that results from different studies on different human cancers can be harmonized. This approach will ultimately increase the depth of our understanding of gene expression signatures across human cancers.

PinX1 is up-regulated and associated with poor patients' survival in gliomas

PinX1, a conserved nuclear protein, could maintain telomere integrity and plays an important role in regulating telomerase activity. It has been reported that the expression of PinX1 is down-regulated in some cancer and associated with cancer prognosis. However, the value of PinX1 in gliomas has not been studied. In this study, two independent retrospective gliomas cohorts with the corresponding gliomas tissue microarrays (TMAs) were established to detect the expression level of PinX1 and the correlation of PinX1 expression with the clinicopathological features and the patients' survival. Compared with non-cancerous brain tissues, PinX1 protein levels were remarkably up-regulated in gliomas (P = 0.001), and further increased from benign gliomas tissues to malignant gliomas tissues (P = 0.090). Moreover, high PinX1 expression was significantly positively associated with gliomas WHO grade in the training set (P = 0.019) and the validation set (P = 0.037). High PinX1 expression significantly correlated with a worse 5-year overall (P = 0.016) and disease-specific survival (P = 0.026). Simultaneously, the multivariate COX regression analysis showed that PinX1 was an independent unfavorable prognostic factor for 5-year overall survival (hazard ratio (HR) = 2.078, P = 0.015) and disease-specific survival (HR = 2.429, P = 0.012) after adjusting with age, sex and WHO grade in gliomas. In conclusion, PinX1 expression may serve as a prognostic and predictive biomarker for gliomas.

PinX1 inhibits the invasion and metastasis of human breast cancer via suppressing NF-κB/MMP-9 signaling pathway

Background

PinX1 (PIN2/TRF1-interacting telomerase inhibitor 1) was suggested to be correlated with tumor progression. This study was designed to evaluate the role of PinX1 in human breast cancer.

Methods

To evaluate the function of PinX1 in breast cancer, we used a tissue microarray (TMA) of 405 human breast cancer patients and immunohistochemistry to analyze the correlation between PinX1 expression and clinicopathologic variables and patient survival. We also detected the abilities of cell migration and invasion in breast cancer by performing cell migration and invasion assay, gelatin zymography and western blot analysis. Lastly, we set up the nude mice model by Tail vein assay to exam the functional role of PinX1 in breast cancer metastasis.

Results

We found that low PinX1 expression was associated with lymph node metastasis (P = 0.002) and histology grade (P = 0.001) in patients, as well as with poorer overall and disease-specific survival (P = 0.010 and P = 0.003, respectively). Moreover, we identified that PinX1 inhibited the migration and invasion of breast cancer by suppressing MMP-9 expression and activity via NF-κB-dependent transcription in vitro. Finally, our mice model confirmed that PinX1 suppressed breast cancer metastasis in vivo.

Conclusions

Our data revealed that low PinX1 expression was an independent negative prognostic factor for breast cancer patients. These findings suggested that PinX1 might be function as a tumor metastasis suppressor in the development and progression of breast cancer by regulating the NF-κB/MMP-9 signaling pathway, and might be a prognostic marker as well as a therapeutic target for breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0332-2) contains supplementary material, which is available to authorized users.

PinX1 inhibits cell proliferation, migration and invasion in glioma cells

PinX1 induces apoptosis and suppresses cell proliferation in some cancer cells, and the expression of PinX1 is frequently decreased in some cancer and negatively associated with metastasis and prognosis. However, the precise roles of PinX1 in gliomas have not been studied. In this study, we found that PinX1 obviously reduced the gliomas cell proliferation through regulating the expressions of cell cycle-relative molecules to arrest cell at G1 phase and down-regulating the expression of component telomerase reverse transcriptase (hTERT in human), which is the hardcore of telomerase. Moreover, PinX1 could suppress the abilities of gliomas cell wound healing, migration and invasion via suppressing MMP-2 expression and increasing TIMP-2 expression. In conclusion, our results suggested that PinX1 may be a potential suppressive gene in the progression of gliomas.