SUPT5H Post-Transcriptional Silencing Modulates PIN1 Expression, Inhibits Tumorigenicity, and Induces Apoptosis of Human Breast Cancer Cells.

BACKGROUND/AIMS: Breast cancer (BrCa) is one of the most common cancers and a highly heterogenous disease, both at the pathological and molecular levels. A common element for the progression of cancer is the presence of aberrant transcription. Targeting the misregulation of transcription may serve as a tool for cancer therapeutics. SUPT5H (Suppressor of Ty 5 homolog) is a highly conserved RNA polymerase II-associated transcription elongation and processivity factor. However, few studies have examined the relationship between SUPT5H and cancer. METHODS: Yeast two-hybrid and colocalization by immunofluorescence were performed to investigate protein-protein interaction. Colony formation assay, CTG assay, and crystal violet assays were performed for cell viability, clonogenicity, and cell proliferation study. Data mining was performed for expression analysis of SUPT5H in breast cancers. Flow cytometry was performed for the assessment of cell cycle and apoptosis. The Transwell chambers were employed for the migration and invasion assays. Quantitative real-time polymerase chain reaction (qRT PCR) and Western blotting were performed to measure the mRNA and protein levels of SUPT5H and other markers related to viability, migration, cell cycle, and apoptosis. Silent mutations were generated for rescue experiments. The biological function of SUPT5H was investigated through siRNA depletion of SUPT5H mRNA in vitro. RESULTS: We showed that SUPT5H is upregulated in breast cancer tissue as compared with the adjacent normal tissue in breast cancer patients. In human breast cancer cells, the levels of SUPT5H and PIN1 are positively correlated with each other. Our biochemical analysis showed that PIN1 interacts with SUPT5H through WW domain, that was required to promote SUPT5H protein stability. Depletion of SUPT5H by siRNA technology reduced the tumorigenic and metastatic properties, promoted s-phase cell cycle arrest and apoptosis of MDA-MB-231 cells. Moreover, depletion of SUPT5H abrogated MAPK molecules thereby regulates the oncogenic behavior of breast cancer cells. CONCLUSION: Our findings demonstrated an essential role of SUPT5H in BrCa tumorigenicity by regulating the expression levels of genes that control proliferation, migration, cell cycle, and apoptosis of breast cancer MDA-MB-231 cells.

The Potential Roles of Tendon Stem/Progenitor Cells in Tendon Aging.

Aging is a key dangerous factor for the occurrence and severity of tendon injury, but the exact cognition of the relationship is elusive at present. More previous studies suggest age-related changes occur at tendon mechanical properties, structure and composition, but the pathological alternations may be overlooked, which might be a cause for the structure and function variations, and even speed up the progress of age-related disorders. Recently, the presence of tendon stem/progenitor cells (TSPCs) would provide new insights for the pathogenesis of tendon aging. In this review, the tendon mechanical properties, structure and composition are presented in brief, then, the pathological changes of the aging tendon are described firstly, and the latest researches on alterations of TSPCs in the pathogenesis of tendon aging have also been analyzed. At a cellular level, the hypothetical model of altered TSPCs fate for tendon aging is also proposed. Moreover, the regulation of TSPCs as a potential way of the therapies for age-related tendon diseases is discussed. Therefore, reversing the impaired function of TSPCs and promoting the tenogenic differentiation of TSPCs could become hot spots for further study and give the opportunity to establish new treatment strategies for age-related tendon injuries.

Cytoplasmic Pin1 expression is correlated with poor prognosis in colorectal cancer.

OBJECTIVE: The aim of this study was to determine the clinicopathological significance and prognostic role of Pin1 expression and subcellular localization in colorectal cancer (CRC). METHODS: The Pin1 expression, as well as cytoplasmic and nuclear localization, was investigated using immunohistochemistry in 265 human CRC tissues. The impact of subcellular localization of Pin1 on clinicopathological significance and prognosis in CRC was evaluated. RESULTS: Pin1 was expressed in 164 of 265 CRCs (61.9%). Pin1 expression was not significantly correlated with any clinicopathological parameters. However, Pin1 expression was significantly correlated with worse overall and recurrence-free survivals (P = 0.002 and P = 0.001, respectively). CRCs with only nuclear Pin1 expression showed no difference in survival compared to CRCs with no Pin1 expression. Over half (51.7%, 137/265) of the CRCs had any cytoplasmic Pin1 expression, and 26.8% (71/265) had both cytoplasmic and nuclear expression. Cytoplasmic Pin1 expression was more frequent than only nuclear or no Pin1 expression in cases with vascular invasion and distant metastasis. Cytoplasmic Pin1 expression was significantly correlated with worse overall and recurrence-free survivals (P < 0.001 and P < 0.001, respectively). CONCLUSION: Taken together, our results indicated different prognostic roles of subcellular Pin1expression in CRC. Cytoplasmic expression of Pin1, with or without nuclear expression, is an important factor in predicting aggressive tumor behavior and worse prognosis.

SUV39H1/DNMT3A-dependent methylation of the RB1 promoter stimulates PIN1 expression and melanoma development.

Melanoma is among the most aggressive and treatment-resistant human cancers. Aberrant histone H3 methylation at Lys 9 (H3K9) correlates with carcinogenic gene silencing, but the significance of suppressor of variegation 3-9 homolog 1 (SUV39H1), an H3K9-specific methyltransferase, in melanoma initiation and progression remains unclear. Here, we show that SUV39H1-mediated H3K9 trimethylation facilitates retinoblastoma ( RB) 1 promoter CpG island methylation by interacting with DNA methyltransferase 3A and decreasing RB mRNA and protein in melanoma cells. Reduced RB abundance, in turn, impairs E2F1 transcriptional inhibition, leading to increased peptidyl-prolyl cis-trans isomerase never-in-mitosis A (NIMA)-interacting 1 (PIN1) levels, human keratinocyte neoplastic cell transformation, and melanoma tumorigenesis via enhanced rapidly accelerated fibrosarcoma 1(RAF1)-MEK-ERK signaling pathway activation. In a synergistic model with B16-F1 murine melanoma cells, SUV39H1 and PIN1 overexpression increased melanoma growth, which was abrogated by their inhibition in SUV39H1-overexpressing B16-F1 mice. SUV39H1 also positively correlated with PIN1 expression in human melanoma. Our studies establish SUV39H1 as an oncogene in melanoma and underscore the role of chromatin factors in regulating tumorigenesis.-Kim, G., Kim, J.-Y., Lim, S.-C., Lee, K. Y., Kim, O., Choi, H. S. SUV39H1/DNMT3A-dependent methylation of the RB1 promoter stimulates PIN1 expression and melanoma development.

miR-874-3p is down-regulated in hepatocellular carcinoma and negatively regulates PIN1 expression.

PIN1 is a peptidyl-prolyl cis/trans isomerase (PPIase) that regulates multiple signaling pathways to control cell fate and is found to be over-expressed in cancers, including hepatocellular carcinoma (HCC). However, the regulation of PIN1 in HCC remains poorly defined. Micro-RNAs (miRNAs) have been reported to play a pivotal role in oncogenesis by targeting the 3'-untranslated region (UTR) of mRNAs encoded by oncogenes and tumour suppressor genes, thereby suppressing the levels of both oncoproteins and tumour suppressors. In this report, we aimed to identify miRNAs that suppress PIN1 expression and to determine their role in HCC. By searching the TargetScan database, miR-874-3p was identified as a potential negative regulator of PIN1. miR-874-3p was demonstrated to bind the 3'UTR of PIN1 mRNA directly to suppress expression of PIN1. Functionally, over-expression of miR-874-3p in HCC cell line PLC/PRF/5 inhibited cell growth and colony formation in-vitro, and promoted cellular apoptosis. Furthermore, these tumour suppressive functions conferred by miR-874-3p were abrogated by over-expression of PIN1. Similarly, expression of miR-874-3p in PLC/PRF/5 with PIN1 knocked-down did not further suppress cellular proliferation, suggesting that PIN1 was a major target of miR-874-3p. More importantly, miR-874-3p was found to be down-regulated in HCC tissues and its expression was negatively correlated with that of PIN1. Down-regulation of miR-874-3p was also associated with poorly differentiated tumour cells, more advanced staging, and inferior patient outcomes. In addition, over-expression of miR-874-3p suppressed tumour growth in vivo. Taken together, our data suggested that miR-874-3p plays a tumour suppressive role in HCC through down-regulation of PIN1.

PIN1 in hepatocellular carcinoma is associated with TP53 gene status.

Phosphorylation of proteins on serine/threonine residues that precede proline (pSer/Thr-Pro) is specifically catalyzed by the peptidyl-prolyl cis-trans isomerase PIN1. PIN1-mediated prolyl-isomerization induces cell cycle arrest and growth inhibition through the regulation of target proteins, including TP53. We examined whether PIN1 acts in a different manner according to TP53 gene status in hepatocellular carcinoma (HCC). We investigated the expression of PIN1 and TP53 proteins in 119 HCC tissue samples. We also analyzed PIN1 expression in combination with TP53 gene mutation and its correlation with the clinical outcome. In addition, we used synthetic small interfering RNA to silence PIN1 gene expression in TP53 wild-type and TP53 mutant HCC cell lines, and then evaluated cell proliferation, migration and invasion. Expression of PIN1 was strongly associated with expression of TP53 protein or TP53 mutation of HCC samples. PIN1 and TP53 expression in TP53 mutant HCC cell lines was higher than that in TP53 wild-type HCC cell lines. Silencing of PIN1 in HLE cells containing mutant TP53 significantly decreased cell proliferation, migration and invasion. In contrast to PIN1 silencing in HLE cells, PIN1 silencing in HepG2 cells containing functional wild-type TP53 resulted in enhanced tumor cell proliferation. HCC patients bearing PIN1 expression with wild-type TP53 were predicted to demonstrate favorable relapse-free survival. Our results suggest that PIN1 plays a role in cancer cell proliferation, migration and invasion in a different manner according to the TP53 gene mutation status in HCC. In particular, interaction of PIN1 with mutant TP53 can act as a tumor promoter and increase its oncogenic activities in HCC.

Cellular peptidyl-prolyl cis/trans isomerase Pin1 facilitates replication of feline coronavirus.

Although feline coronavirus (FCoV) causes feline infectious peritonitis (FIP), which is a fatal infectious disease, there are no effective therapeutic medicines or vaccines. Previously, in vitro studies have shown that cyclosporin (CsA) and FK506 inhibit virus replication in diverse coronaviruses. CsA and FK506 are targets of clinically relevant immunosuppressive drugs and bind to cellular cyclophilins (Cyps) or FK506 binding proteins (FKBPs), respectively. Both Cyp and FKBP have peptidyl-prolyl cis-trans isomerase (PPIase) activity. However, protein interacting with NIMA (Pin1), a member of the parvulin subfamily of PPIases that differs from Cyps and FKBPs, is essential for various signaling pathways. Here we demonstrated that genetic silencing or knockout of Pin1 resulted in decreased FCoV replication in vitro. Dipentamethylene thiuram monosulfide, a specific inhibitor of Pin1, inhibited FCoV replication. These data indicate that Pin1 modulates FCoV propagation.

p53 negatively regulates Pin1 expression under ER stress.

Accumulating evidence suggests that endoplasmic reticulum (ER) stress plays a major role in the development of many diseases. A previous study indicated that the apoptotic regulator p53 is significantly increased in response to ER stress and participates in ER stress-induced apoptosis. However, the regulators of p53 expression during ER stress are still not fully understood. Here, we investigated whether p53 contributes to the impairment of Pin1 signaling under ER stress. We found that treatment with thapsigargin, a stimulator of p53 expression and an inducer of ER stress, decreased Pin1 expression in HCT116 cells. Also, we identified functional p53 response elements (p53REs) in the Pin1 promoter. Overexpression of p53 significantly decreased Pin1 expression in HCT116 cells while abolition of p53 gene expression induced Pin1 expression. Pin1 expression was significantly increased by treatment with the p53 inhibitor pifithrin-α or down-regulation of p53 expression. Taken together, ER stress decreased Pin1 expression through p53 activation, and this mechanism may be associated with ER stress-induced cell death. These data reported here support the importance of Pin1 as a potential target molecule mediating tumor development.