PTPN12 Affects Nasopharyngeal Carcinoma Cell Proliferation and Migration Through Regulating EGFR.

OBJECTIVE: Nasopharyngeal carcinoma (NPC) shows the leading morbidity in otorhinolaryngological malignant tumor. It is a common malignancy in China with obvious reginal distribution. NPC is a polygenic disease that is affected by numerous factors. Protein tyrosine phosphatase nonreceptor type 12 (PTPN12) regulates multiple tumor proliferation and development, including breast cancer and colon cancer. However, the role of PTPN12 in NPC occurrence and development has not been elucidated. PATIENTS AND METHODS: NPC cell line CNE2 was cultured in vitro and divided into three groups, including control, empty plasmid, and PTPN12 groups. PTPN12 mRNA and protein expressions were tested by real-time polymerase chain reaction and Western blot. CNE2 cell proliferation was detected by MTT assay. Cell migration was determined by wound healing assay. Cell apoptosis was evaluated by caspase 3 activity detection. Epidermal growth factor receptor (EGFR) expression was assessed by Western blot. RESULTS: PTPN12 plasmid transfection increased PTPN12 mRNA and protein expressions, suppressed cell proliferation and migration, reduced EGFR level, and enhanced caspase 3 activity compared with control and empty plasmid groups (p < 0.05). CONCLUSIONS: PTPN12 regulates NPC proliferation and migration through negative regulating EGFR. It could be treated as a molecular target for NPC diagnosis and prognosis analysis.

ACTH Modulates PTP-PEST Activity and Promotes Its Interaction With Paxillin.

Adrenocorticotropic hormone (ACTH) treatment has been proven to promote paxillin dephosphorylation and increase soluble protein tyrosine phosphatase (PTP) activity in rat adrenal zona fasciculata (ZF). Also, in-gel PTP assays have shown the activation of a 115-kDa PTP (PTP115) by ACTH. In this context, the current work presents evidence that PTP115 is PTP-PEST, a PTP that recognizes paxillin as substrate. PTP115 was partially purified from rat adrenal ZF and PTP-PEST was detected through Western blot in bioactive samples taken in each purification step. Immunohistochemical and RT-PCR studies revealed PTP-PEST expression in rat ZF and Y1 adrenocortical cells. Moreover, a PTP-PEST siRNA decreased the expression of this phosphatase. PKA phosphorylation of purified PTP115 isolated from non-ACTH-treated rats increased KM and VM . Finally, in-gel PTP assays of immunoprecipitated paxillin from control and ACTH-treated rats suggested a hormone-mediated increase in paxillin-PTP115 interaction, while PTP-PEST and paxillin co-localize in Y1 cells. Taken together, these data demonstrate PTP-PEST expression in adrenal ZF and its regulation by ACTH/PKA and also suggest an ACTH-induced PTP-PEST-paxillin interaction. J. Cell. Biochem. 117: 2170-2181, 2016. © 2016 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc.

Transcriptome analysis of phycocyanin inhibitory effects on SKOV-3 cell proliferation.

Phycocyanin (PC) from Spirulina platensis has inhibitory effects on tumor cell growth. In this research, the transcriptome study was designed to investigate the underlying molecular mechanisms of PC inhibition on human ovarian cancer cell SKOV-3 proliferation. The PC IC50 was 216.6µM and 163.8µM for 24h and 48h exposure, respectively, as determined by CCK-8 assay. The morphological changes of SKOV-3 cells after PC exposure were recorded using HE staining. Cells arrested in G2/M stages as determined by flow cytometry. The transcriptome analysis showed that 2031 genes (with > three-fold differences) were differentially expressed between the untreated and the PC-treated cells, including 1065 up-regulated and 966 down-regulated genes. Gene ontology and KEGG pathway analysis identified 18 classical pathways that were remarkably enriched, such as neurotrophin signaling pathway, VEGF signaling pathway and P53 signaling pathway. qPCR results further showed that PTPN12, S100A2, RPL26, and LAMA3 increased while HNRNPA1P10 decreased in PC-treated cells. Molecules and genes in those pathways may be potential targets to develop treatments for ovarian cancer.

The prognostic significance of tyrosine-protein phosphatase nonreceptor type 12 expression in nasopharyngeal carcinoma.

Tyrosine-protein phosphatase nonreceptor type 12 (PTPN12) has been proposed to predict prognosis of various human cancers. However, the clinicopathologic and prognostic significance of PTPN12 expression in NPC has not yet been elucidated. The objective of this study was to investigate the clinicopathological and prognostic implication of PTPN12 in nasopharyngeal carcinoma (NPC) patients. Protein expression levels of PTPN12 were explored by semiquantitative immunohistochemical staining on archival formalin-fixed, paraffin-embedded pathological specimens consisting of 203 NPCs, and 40 normal nasopharyngeal mucosa tissues. Receiver operating characteristic (ROC) curve analysis was employed to determine the cutoff score of PTPN12 expression in NPCs. The PTPN12 immunohistochemical staining results were then correlated with various clinicopathological features and patients' prognosis using various statistical models. Our results showed that decreased expression of PTPN12 was more frequently observed in NPC tissues compared with the normal nasopharyngeal mucosa. Further correlation analyses indicated that the decreased expression of PTPN12 was significantly associated with tumor T classification, N classification, distant metastasis, and clinical stage in NPCs (P < 0.05). Univariate analysis showed a significant association between the decreased expression of PTPN12 and adverse overall survival and disease-free survival (P < 0.05). More importantly, multivariate analysis identified the PTPN12 expression in NPC as an independent prognostic factor. The decrease expression of PTPN12 might be important in conferring a more aggressive behavior in NPC. Thus, PTPN12 expression may be used as a novel independent prognostic biomarker for patients with NPC.

Protein tyrosine phosphatase-PEST (PTP-PEST) regulates mast cell-activating signals in PTP activity-dependent and -independent manners.

Aggregation of the high-affinity IgE receptor (FcεRI) in mast cells leads to degranulation and production of numerous cytokines and lipid mediators that promote allergic inflammation. Tyrosine phosphorylation of proteins in response to FcεRI aggregation has been implicated in mast cell activation. Here, we determined the role of PTP-PEST (encoded by PTPN12) in the regulation of mast cell activation using the RBL-2H3 rat basophilic leukemia cell line as a model. PTP-PEST expression was significantly induced upon FcεRI-crosslinking, and aggregation of FcεRI induced the phosphorylation of PTP-PEST at Ser39, thus resulting in the suppression of PTP activity. By overexpressing a phosphatase-dead mutant (PTP-PEST CS) and a constitutively active mutant (PTP-PEST SA) in RBL-2H3 cells, we showed that PTP-PEST decreased degranulation and enhanced IL-4 and IL-13 transcription in FcεRI-crosslinked RBL-2H3 cells, but PTP activity of PTP-PEST was not necessary for this regulation. However, FcεRI-induced TNF-α transcription was increased by the overexpression of PTP-PEST SA and suppressed by the overexpression of PTP-PEST CS. Taken together, these results suggest that PTP-PEST is involved in the regulation of FcεRI-mediated mast cell activation through at least two different processes represented by PTP activity-dependent and -independent pathways.

Protein tyrosine phosphatase with proline-glutamine-serine-threonine-rich motifs negatively regulates TLR-triggered innate responses by selectively inhibiting IκB kinase ß/NF-κB activation.

TLRs are essential for sensing the invading pathogens and initiating protective immune responses. However, aberrant activation of TLR-triggered inflammatory innate responses leads to the inflammatory disorders and autoimmune diseases. The molecular mechanisms that fine-tune TLR responses remain to be fully elucidated. Protein tyrosine phosphatase with proline-glutamine-serine-threonine-rich motifs (PTP-PEST) has been shown to be important in cell adhesion, migration, and also T cell and B cell activation. However, the roles of PTP-PEST in TLR-triggered immune response remain unclear. In this study, we report that PTP-PEST expression was upregulated in macrophages by TLR ligands. PTP-PEST inhibited TNF-α, IL-6, and IFN-ß production in macrophages triggered by TLR3, TLR4, and TLR9. Overexpression of catalytically inactive mutants of PTP-PEST abolished the inhibitory effects, indicating that PTP-PEST inhibits TLR response in a phosphatase-dependent manner. Accordingly, PTP-PEST knockdown increased TLR3, -4, and -9-triggered proinflammatory cytokine and type I IFN production. PTP-PEST selectively inhibited TLR-induced NF-κB activation, whereas it had no substantial effect on MAPK and IFN regulatory factor 3 activation. Moreover, PTP-PEST directly interacted with IκB kinase ß (IKKß) then inhibited IKKß phosphorylation at Ser(177/181) and Tyr(188/199), and subsequently suppressed IKKß activation and kinase activity as well as downstream NF-κB activation, resulting in suppression of the TLR-triggered innate immune response. Thus, PTP-PEST functions as a feedback-negative regulator of TLR-triggered innate immune responses by selectively impairing IKKß/NF-κB activation.