Aiphanol, a multi-targeting stilbenolignan, potently suppresses mouse lymphangiogenesis and lymphatic metastasis.

The high incidence of lymphatic metastasis is closely related to poor prognosis and mortality in cancers. Potent inhibitors to prevent pathological lymphangiogenesis and lymphatic spread are urgently needed. The VEGF-C-VEGFR3 pathway plays a vital role in driving lymphangiogenesis and lymph node metastasis. In addition, COX2 in tumor cells and tumor-associated macrophages (TAMs) facilitates lymphangiogenesis. We recently reported that aiphanol, a natural stilbenolignan, attenuates tumor angiogenesis by repressing VEGFR2 and COX2. In this study, we evaluated the antilymphangiogenic and antimetastatic potency of aiphanol using in vitro, ex vivo and in vivo systems. We first demonstrated that aiphanol directly bound to VEGFR3 and blocked its kinase activity with an half-maximal inhibitory concentration (IC50) value of 0.29 µM in an in vitro ADP-GloTM kinase assay. Furthermore, we showed that aiphanol (7.5-30 µM) dose-dependently counteracted VEGF-C-induced proliferation, migration and tubular formation of lymphatic endothelial cells (LECs), which was further verified in vivo. VEGFR3 knockdown markedly mitigated the inhibitory potency of aiphanol on lymphangiogenesis. In 4T1-luc breast tumor-bearing mice, oral administration of aiphanol (5 and 30 mg· kg-1 ·d-1) dose-dependently decreased lymphatic metastasis and prolonged survival time, which was associated with impaired lymphangiogenesis, angiogenesis and, interestingly, macrophage infiltration. In addition, we found that aiphanol decreased the COX2-dependent secretion of PGE2 and VEGF-C from tumor cells and macrophages. These results demonstrate that aiphanol is an appealing agent for preventing lymphangiogenesis and lymphatic dissemination by synergistically targeting VEGFR3 and inhibiting the COX2-PGE2-VEGF-C signaling axis.

PRL-3 promotes telomere deprotection and chromosomal instability.

Phosphatase of regenerating liver (PRL-3) promotes cell invasiveness, but its role in genomic integrity remains unknown. We report here that shelterin component RAP1 mediates association between PRL-3 and TRF2. In addition, TRF2 and RAP1 assist recruitment of PRL-3 to telomeric DNA. Silencing of PRL-3 in colon cancer cells does not affect telomere integrity or chromosomal stability, but induces reactive oxygen species-dependent DNA damage response and senescence. However, overexpression of PRL-3 in colon cancer cells and primary fibroblasts promotes structural abnormalities of telomeres, telomere deprotection, DNA damage response, chromosomal instability and senescence. Furthermore, PRL-3 dissociates RAP1 and TRF2 from telomeric DNA in vitro and in cells. PRL-3-promoted telomere deprotection, DNA damage response and senescence are counteracted by disruption of PRL-3-RAP1 complex or expression of ectopic TRF2. Examination of clinical samples showed that PRL-3 status positively correlates with telomere deprotection and senescence. PRL-3 transgenic mice exhibit hallmarks of telomere deprotection and senescence and are susceptible to dextran sodium sulfate-induced colon malignancy. Our results uncover a novel role of PRL-3 in tumor development through its adverse impact on telomere homeostasis.

Repressor activator protein 1-promoted colorectal cell migration is associated with the regulation of Vimentin.

Repressor activator protein 1 plays important roles in telomere protection, while repressor activator protein 1 binds to extra-telomeric DNA and exerts the function as a transcriptional regulator. Previous study showed that repressor activator protein 1 regulates the transcriptional activity of nuclear factor-κB, and it was highly expressed in breast cancer tissues; however, the clinical significance of repressor activator protein 1 expression in cancer remains to be elucidated. In this study, we discovered that repressor activator protein 1 was highly expressed in colorectal cancer tissues. High expression of repressor activator protein 1 was significantly correlated with poor prognosis and distant metastasis. Knockdown of repressor activator protein 1 in colorectal cancer cells did not affect cell proliferation or colony formation, but dramatically decreased cell migration and F-actin-enriched membrane protrusions. Microarray screening revealed that Vimentin was downregulated after repressor activator protein 1 knockdown, which was validated by analysis of a colorectal cancer dataset. Furthermore, knockdown of Vimentin attenuated repressor activator protein 1-enhanced cell migration. Thus, our study suggests that repressor activator protein 1 is a prognostic marker and a potential target for colorectal cancer therapy.

Sarsaparilla (Smilax Glabra Rhizome) Extract Activates Redox-Dependent ATM/ATR Pathway to Inhibit Cancer Cell Growth by S Phase Arrest, Apoptosis, and Autophagy.

Sarsaparilla (Smilax Glabra Rhizome) exerts growth inhibitory effect on multiple cancer cells in vitro and in vivo, and redox-dependent persistent activation of ERK1/2 has been reported to underlie this effect. Here, we report an activation of ATM/ATR-dependent signaling pathway also as a mechanism for the cancer cell growth inhibition induced by the supernatant fraction of the water-soluble extract from sarsaparilla (SW). SW treatment (3.5 µg/µL) promoted the phosphorylations of ATM, ATR, and CHK1 in AGS and HT-29 cells. The ATM kinase inhibitor, KU55933, could reverse SW-induced ERK phosphorylation but not the reduced glutathione/oxidized glutathione (GSH/GSSG) imbalance in AGS cells. However, both the redox inhibitor glutathione (GSH) and ERK inhibitor U0126 antagonized SW-induced phosphorylations of ATM, ATR, and CHK1 in AGS cells. We further found KU55933 significantly antagonized SW-induced S phase arrest, apoptosis, autophagy and the resultant cell growth inhibition. Our results provide another molecular basis for the anticancer action of sarsaparilla.

Integrated analysis identified an intestinal-like and a diffuse-like gene sets that predict gastric cancer outcome.

The two major histological types of gastric cancer, intestinal and diffuse subtypes, have distinct epidemiological and pathophysiological features and were also suggested to be of diverse clinical outcomes. Although the gene expression spectrum of gastric cancer subtypes has been reported by previous studies, its linkage with gastric cancer clinical features and outcomes remains elusive. We investigated large-sample online gastric cancer datasets for seeking genes correlated with the clinical diversities between gastric cancer intestinal and diffuse subtypes. Genes differently expressed between the two subtypes were assessed by multiple statistical analysis and were testified on cellular level by quantitative RT-PCR. Related genes were combined to generate a risk signature, and their mutual linkages were also explored. Among genes overexpressed in intestinal subtype, ATPIF1, PRDX2, PRKAR2A, and SMC1A were correlated with positive prognosis. Among genes overexpressed in diffuse subtype, DTNA, GPR161, IDS, RHOQ, and TSHZ2 were correlated with negative prognosis. These nine genes were all novel independent prognostic factors. When used in combination as signatures, these two gene sets displayed strong efficacy for prediction of the prognosis and clinical variables in gastric and colorectal cancer. Hence, these two genes sets were respectively defined as the favorable intestinal-like and adverse diffuse-like gene sets. We identified nine novel genes correlated with the clinical diversity between the intestinal and diffuse subtypes of gastric cancer. The malignant changes from the intestinal to diffuse subtype might be due to the reduction of the four intestinal-like genes, as well as the elevation of the five diffuse-like genes.

HNRNPC as a candidate biomarker for chemoresistance in gastric cancer.

Chemoresistance is a major cause of treatment failure and high mortality in advanced gastric cancer (AGC). Currently, the mechanism of chemoresistance remains unclear, and there is no biomarker to accurately predict the efficacy of chemotherapy. In the present study, we established human gastric cancer (GC) cell lines resistant to 5-fluorouracil (5FU), paclitaxel (TA), or cisplatin (DDP) by gradient drug treatment and generated a novel monoclonal antibody 5B2 targeting heterogeneous nuclear ribonucleoproteins C1/C2 (HNRNPC) overexpressed in chemoresistant GC cells. Overexpressing HNRNPC in GC cells promoted chemoresistance, and knockdown of HNRNPC by small interfering RNA (siRNA) reversed chemoresistance. By utilizing available datasets, we demonstrated that high level of HNRNPC transcript indicated poor overall survival (OS) and free of progression (FP). HNRNPC expression was negatively correlated with OS of GC patients treated with 5FU-based drugs and with time to progression (TTP) of GC patients treated with CF regimen. These data suggest the potential usefulness of HNRNPC as a prognostic and therapeutic marker of GC.

Overexpression of synuclein-γ predicts lack of benefit from radiotherapy for breast cancer patients.

BACKGROUND: Although radiotherapy following mastectomy was demonstrated to reduce the recurring risk and improve the prognosis of patients with breast cancer, it is also notorious for comprehensive side effects, hence only a selected group of patients can benefit. Therefore, the screening of molecular markers capable of predicting the efficacy of radiotherapy is essential. METHODS: We have established a cohort of 454 breast cancer cases and selected 238 patients with indications for postoperative radiotherapy. Synuclein-γ (SNCG) protein levels were assessed by immunohistochemistry, and SNCG status was retrospectively correlated with clinical features and survival in patients treated or not treated with radiotherapy. Gene Set Enrichment Analysis (GSEA) and survival analysis for online datasets were also performed for further validation. RESULTS: Among patients that received radiotherapy (82/238), those demonstrating positive SNCG expression had a 55.0 month shorter median overall survival (OS) in comparison to those demonstrating negative SNCG expression (78.4 vs. 133.4 months, log rank χ (2) = 16.13; p < 0.001). Among the patients that received no radiotherapy (156/238), SNCG status was not correlated with OS (log rank χ (2) = 2.40; p = 0.121). A COX proportional hazard analysis confirmed SNCG as an independent predictor of OS, only for patients who have received radiotherapy. Similar results were also obtained for distant metastasis-free survival (DMFS). A GSEA analysis indicated that SNCG was strongly associated with genes related to a radiation stress response. A survival analysis was performed with online databases consisting of breast cancer, lung cancer, and glioblastoma and further confirmed SNCG's significance in predicting the survival of patients that have received radiotherapy. CONCLUSION: A positive SNCG may serve as a potential marker to identify breast cancer patients who are less likely to benefit from radiotherapy and may also be extended to other types of cancer. However, the role of SNCG in radiotherapy response still needs to be further validated in randomized controlled trials prior to being exploited in clinical practice.

Fibrinogen-derived fibrinostatin inhibits tumor growth through anti-angiogenesis.

Angiogenesis is a prerequisite of tumor growth and metastasis and, thus, anti-angiogenesis treatment has become an important part of cancer therapy. A 15-amino acid peptide of the fibrinogen α chain, fibrinostatin, was previously found in serum samples of gastric cancer patients. Herein we demonstrated that fibrinostatin has anti-angiogenesis activity in several angiogenesis models and it reduces tumor growth in mouse xenografts and allografts. Increased tumor necrosis and reduced microvessel density in tumors were observed in mouse xenograft models. Fibrinostatin inhibited proliferation and induced apoptosis in HUVEC, but not in cancer cells. In addition, fibrinostatin specifically entered HUVEC. Fibrinostatin also prevented migration, adhesion and tubule formation of HUVEC in vitro. A single-dose acute toxicity testing and a repeated-dose chronic toxicity study in the mouse, rat and monkey indicated that fibrinostatin had a wide margin of safety. Taken together, fibrinostatin shows promise as a potential anti-angiogenesis therapeutic agent.

Inhibition of STAT5a by Naa10p contributes to decreased breast cancer metastasis.

N-α-Acetyltransferase 10 protein (Naa10p, also called arrest-defective 1), the catalytic subunit of N-acetyltransferase A, is a critical regulator of cell death and proliferation. Naa10p is also shown to regulate cancer metastasis by inhibiting cell motility; however, its role in cancer metastasis is not fully understood. In this study, we found that high expression of Naa10p is positively correlated with the survival of patients with breast cancer, whereas negatively correlated with lymph node metastasis. Naa10p inhibits breast cancer cell migration and invasion in vitro and decreases the xenograft growth and metastasis in nude mice. Microarray screening revealed that Naa10p downregulates inhibitors of differentiation 1 (ID1) expression. Naa10p binds to signal transducer and activator of transcription 5a (STAT5a) and decreases STAT5a-stimulated ID1 expression in an acetyltransferase-independent manner. Moreover, Naa10p antagonizes Janus kinase 2-STAT5a signaling by lowering p65-activated interleukin-1ß expression. Our results demonstrate a novel mechanism through which Naa10p inhibits the metastasis of breast cancer cells by targeting STAT5a.

High NR2F2 transcript level is associated with increased survival and its expression inhibits TGF-ß-dependent epithelial-mesenchymal transition in breast cancer.

NR2F2, a member of nuclear receptor subfamily 2, was shown to be associated with cancer, but its role in breast malignancy remains unclear. In this study, we aimed to explore the function of NR2F2 in breast cancer. We browsed GEO and TCGA databases and used Kaplan-Meier survival analysis to explore the association between NR2F2 transcript level and patient survival in breast cancer. NR2F2 expression in breast cancer tissues was evaluated by immunohistochemistry staining. NR2F2-related functions and its role in Epithelial-Mesenchymal Transition (EMT) were predicted by Gene Set Enrichment Analysis (GSEA) and validated by in vitro assays with NR2F2 knockdown MDA-MB231 and MCF7 cells. We found high NR2F2 transcript level was correlated with favorable overall survival and distant metastasis-free survival. Positive rate of NR2F2 protein tended to be decreased with the progression of malignancy. Results of in vitro migration and invasion assays suggested NR2F2's potential in inhibiting invasiveness. NR2F2 was predicted to be negatively linked with EMT and TGF-ß-pathway related genes, which was supported by observation of EMT-like morphology and changes in EMT-markers E-cadherin and Slug. Additionally, we found TGF-ß inhibited the expression of NR2F2. GSEA also predicted that NR2F2 could be inversely associated with chemoresistance, which was verified by results of in vitro growth inhibition assays using chemotherapeutic agents. Our results demonstrated high NR2F2 transcript level was associated with favorable clinical outcome, which might be due to NR2F2's inhibitory effect on TGF-ß-dependent EMT and its role in inhibiting chemoresistance.

Activation of EGFR-PI3K-AKT signaling is required for Mycoplasma hyorhinis-promoted gastric cancer cell migration.

Persistent infection of Mycoplasma hyorhinis (M. hyorhinis) was associated with gastric cancer cell migration and invasion, but the mechanisms were not well understood. Herein, we found that M. hyorhinis activated phosphoinositide 3-kinase (PI3K)-AKT signaling axis in gastric cancer cell lines. Epidermal growth factor receptor (EGFR) was upstream of PI3K-AKT signaling in the context of M. hyorhinis infection, because phosphorylation of AKT Serine 473 was almost completely attenuated by the EGFR inhibitor AG1478 or by EGFR knockdown. Phosphorylation of AKT S473 induced by M. hyorhinis infection was also abolished by PI3K inhibitor wortmannin. Furthermore, we found that p37, a membrane protein of M. hyorhinis, could also promote M. hyorhinis-induced PI3K-AKT signaling activation and cell migration. In addition, pre-treatment with AG1478 or wortmannin significantly inhibited cell migration induced by M. hyorhinis infection or p37 treatment. In conclusion, EGFR-PI3K-AKT signaling plays an important role in M. hyorhinis-promoted cell migration in gastric cancer cells, thus providing a clue to the pathogenesis of M. hyorhinis in gastric cancer.

[Establishment of drug resistant cell line of MGC-803 and analysis of differential secretome].

OBJECTIVE: To identify chemoresistance-associated secretory proteins by proteomic approaches, and to provide the basis for selecting suitable chemotherapy in gastric cancer treatment. METHODS: Drug resistant cell lines were established by gradient drug treatment with MGC-803 gastric cancer cells. The secreted proteins of MGC-803 parental and resistant cells were collected from the conditional medium without serum and separated by two-dimensional gel electrophoresis (2-DE).The proteins were analyzed by PD Quest 7.1.0 software and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Real-time RT-PCR was performed to confirm the difference of expression on the mRNA level. RESULTS: The 5-fluorouracil (5FU), paclitaxel (TA) and cisplatin (DDP)-resistant gastric cancer cell lines with the resistance indexes of 110.6, 70.0 and 13.3 respectively, were established successfully. DDP-resistant cells had strong cross-resistance to 5FU and TA, and the resistance indexes were 23.5 and 114.0. 5FU-resistant cells also had strong cross-resistance to TA with the resistance index 70.0. The 2-DE patterns of protein component spectra from the conditional medium were obtained with 18 proteins whose abundances were increased in all chemoresistance cells for more than 2-fold, 13 of which were identified by mass spectrometry, including protease and proteins involved in signal transduction. Compared with the parental cell MGC-803, SLMAP, TOP3A, DYNC1H1, RHPN1, PUF60 and SIAH1 were significantly up-regulated in three drug resistant cells, IFT172 and FILIP were up-regulated in 5FU-resistant and TA-resistant cells, PLVAP and LMNA were up-regulated in TA- and DDP-resistant cells. Further validation revealed that SIAH1 protein was enriched in cell lysates and the conditional medium from all the drug resistant cells. CONCLUSION: By establishing the 5FU-,TA- and DDP-resistant gastric cancer cell lines and assisted by 2-DE and mass spectrometry, we demonstrated the different secretory protein profiling and found that SIAH1 had significantly increased in both cell lysates and the conditional medium of the drug-resistant cells, which are potential candidates for developing chemoresistance markers in sera from gastric cancer patients.

PES1 regulates sensitivity of colorectal cancer cells to anticancer drugs.

PES1 (also known as Pescadillo), a nucleolar protein, was involved in biogenesis of ribosomal RNA. Up-regulation of PES1 has been documented in some human cancers, indicating that PES1 may play some crucial roles in tumorigenesis. In our previous study, it was found that silencing of PES1 resulted in decreased proliferation of colorectal cancer cells. We also noticed that depletion of PES1 altered expression profiles of diverse genes. In the present study, we validated the expression changes of a subset of genotoxic stress-related genes in PES1-silenced HCT116 cells by quantitative RT-PCR. The steady and etoposide-induced phosphorylated H2AX (γ-H2AX) were higher in PES1-silenced cells than in control cells. Besides, etoposide-induced γ-H2AX persisted longer in PES1-silenced cells after removing the etoposide. Next, results of comet assay revealed decreased DNA repair after PES1-ablation. PES1-ablated cells were more sensitive to chemotherapeutic agents, which could be reversed by reconstitution with exogenous PES1. Furthermore, deletion of PES1 diminished steady and DNA damage-induced levels of nuclear RAD51. Our results uncover a potential role of PES1 in chemoresistance by regulating DNA damage response in colorectal cancer cells.

PRL-3 activates NF-κB signaling pathway by interacting with RAP1.

Phosphatase of regenerating liver (PRL-3) promotes cancer metastasis through enhanced cell motility and invasiveness, however its role in tumorigenesis remains unclear. Herein, we reported that PRL-3 interacts with telomere-related protein RAP1. PRL-3 promotes the cytosolic localization of RAP1, which is counteracted by silencing of PRL-3. Immunohistochemical staining of colon cancer tissue array (n=170) revealed that high level of PRL-3 associates with cytosolic localization of RAP1 (p=0.01). Microarray analysis showed that PRL-3 regulates expression of diverse genes and enhances phosphorylation of p65 subunit of NF-κB in a RAP1-dependent manner. Furthermore, PRL-3 transcriptionally activates RAP1 expression, which is counteracted by ablating p65. Therefore, our results demonstrate PRL-3 as a novel regulator of NF-κB signaling pathway through RAP1.

Critical role for Daxx in regulating Mdm2.

The tumour suppressor p53 induces apoptosis or cell-cycle arrest in response to genotoxic and other stresses. In unstressed cells, the anti-proliferative effects of p53 are restrained by mouse double minute 2 (Mdm2), a ubiquitin ligase (E3) that promotes p53 ubiquitination and degradation. Mdm2 also mediates its own degradation through auto-ubiquitination. It is unclear how the cis- and trans-E3 activities of Mdm2, which have opposing effects on cell fate, are differentially regulated. Here, we show that death domain-associated protein (Daxx) is required for Mdm2 stability. Downregulation of Daxx decreases Mdm2 levels, whereas overexpression of Daxx strongly stabilizes Mdm2. Daxx simultaneously binds to Mdm2 and the deubiquitinase Hausp, and it mediates the stabilizing effect of Hausp on Mdm2. In addition, Daxx enhances the intrinsic E3 activity of Mdm2 towards p53. On DNA damage, Daxx dissociates from Mdm2, which correlates with Mdm2 self-degradation. These findings reveal that Daxx modulates the function of Mdm2 at multiple levels and suggest that the disruption of the Mdm2-Daxx interaction may be important for p53 activation in response to DNA damage.

Anti-PAI-1 Monoclonal Antibody Inhibits the Metastasis and Growth of Esophageal Squamous Cell Carcinoma.

Plasminogen activator inhibitor (PAI-1) is highly expressed in esophageal squamous cell carcinoma (ESCC) and strongly contributes to metastasis, making it a potential target for ESCC therapy. However, the antibodies and inhibitors targeting PAI-1 have not shown good therapeutic effect in the in vivo experiments yet. Here, we generated a panel of novel monoclonal antibodies (mAbs) against PAI-1. Analysis of PAI-1 expression in 90 tissue specimens and 128 serum specimens from ESCC patients with these mAbs confirmed that PAI-1 levels was significantly correlated with metastasis and poor survival. In addition, we found that high PAI-1 expression contributed to the enhanced motility and invasiveness of two ESCC cell lines. Next, mAb-1E2 and mAb-2E3, which have highest affinity with PAI-1, were shown to possess strong inhibitory effects on ESCC migration and invasion. Anti-tumor and anti-metastatic effects of mAb-2E3 were further demonstrated in the experimental animal models. Finally, LRP1 was identified as key factor mediating the pro-invasive function of PAI-1 and the anti-invasive capacity of mAb-2E3 in ESCC cells. The mAb-2E3 markedly decreased STAT1 phosphorylation levels and blocked the binding between PAI-1 and LRP1-ClusterII domain. Collectively, mAb-2E3 developed by our lab may be an effective antibody drug which can be used for anti-metastatic therapy in ESCC.

Anti-PRL-3 Monoclonal Antibody inhibits the Growth and Metastasis of colorectal adenocarcinoma.

Background: Colon cancer is the one of leading causes of cancer-related death. Chemotherapy, radiotherapy and immunotherapy will be the mainstream in inoperable advanced cancer in clinics. Precision treatment is still lack in colon cancer. Materials and Methods: We developed a series of mAbs targeting PRL-3 through different types of immunogens. The binding domains of mAbs were identified through the ELISA and Western blotting experiments. The antitumor activity of mAbs was verified by cell proliferation, migration and invasion experiments. Xenograft subcutaneous and metastatic models and patient derived Xenograft (PDX) model were established. Results: mAb 12G12 targeting 77-120AA exhibited inhibition in migration and invasion experiments. 12G12 inhibited the migration of multiple types of cancer cells, including colon cancer, gastric cancer, esophagus cancer, liver cancer, lung cancer and pancreatic cancer cells. 12G12 decreased the tumor growth and metastasis in Xenograft subcutaneous and metastatic tumor model, respectively. The antitumor activity of mAb 12G12 was also confirmed in PDX model of gastric cancer. PRL-3 interacted with Golgi protein TMED10. Knockdown of TMED10 expression attenuated the cell migration triggered by purified GST-PRL-3 protein. Conclusion: Our results confirmed the antitumor activity of mAb 12G12 in colorectal adenocarcinoma and provided a new potential targeted therapy of colon cancer.

N-α-acetyltransferase 10 protein inhibits apoptosis through RelA/p65-regulated MCL1 expression.

N-α-Acetyltransferase 10 protein (Naa10p/ARD1), the catalytic subunit of N-acetyltransferase A, catalyzes both N-α-acetylation and ε-acetylation, as well as autoacetylation. Naa10p is involved in controlling cell proliferation, apoptosis, autophagy and neuronal development. Our group and others had reported prognostic value of Naa10p expression in various types of cancer. Despite the efforts to elucidate the biological function of Naa10p, it remains controversial regarding its roles in tumor development. Herein, we report that depletion of Naa10p inhibited the growth of xenograft tumors in nude mice. Microarray analysis identified MCL1 gene as one of targets downstream of Naa10p. Naa10p positively regulated MCL1 expression, as exogenous Naa10p promoted MCL1 expression, whereas Naa10p silencing decreased MCL1 expression. Ablation of Naa10p sensitized cancer cells to stimuli-induced apoptosis, and the anti-apoptotic function of Naa10p was, at least in part, mediated by MCL1. Mechanistically, we found a physical interaction between Naa10p and RelA/p65. Transcriptional activation of the MCL1 gene required the recruitment of Naa10p-RelA/p65 complex to the p65-binding site of MCL1 promoter region. We also demonstrated a positive correlation between MCL1 and Naa10p messenger RNA levels in both colon cancer and lung cancer tissues. These results indicate that Naa10p inhibits apoptosis through Naa10p-RelA/p65-dependent MCL1 transcriptional activation.

Phosphatase of regenerating liver-3 directly interacts with integrin ß1 and regulates its phosphorylation at tyrosine 783.

BACKGROUND: Phosphatase of regenerating liver-3 (PRL-3 or PTP4A3) has been implicated in controlling cancer cell proliferation, motility, metastasis, and angiogenesis. Deregulated expression of PRL-3 is highly correlated with cancer progression and predicts poor survival. Although PRL-3 was categorized as a tyrosine phosphatase, its cellular substrates remain largely unknown. RESULTS: We demonstrated that PRL-3 interacts with integrin ß1 in cancer cells. Recombinant PRL-3 associates with the intracellular domain of integrin ß1 in vitro. Silencing of integrin α1 enhances PRL-3-integrin ß1 interaction. Furthermore, PRL-3 diminishes tyrosine phosphorylation of integrin ß1 in vitro and in vivo. With site-specific anti-phosphotyrosine antibodies against residues in the intracellular domain of integrin ß1, tyrosine-783, but not tyrosine-795, is shown to be dephosphorylated by PRL-3 in a catalytic activity-dependant manner. Phosphorylation of Y783 is potentiated by ablation of PRL-3 or by treatment with a chemical inhibitor of PRL-3. Conversely, depletion of integrin α1 decreases the phosphorylation of this site. CONCLUSIONS: Our results revealed a direct interaction between PRL-3 and integrin ß1 and characterized Y783 of integrin ß1 as a bona fide substrate of PRL-3, which is negatively regulated by integrin α1.

Elevated serum synuclein-gamma in patients with gastrointestinal and esophageal carcinomas.

BACKGROUND/AIMS: We aimed to evaluate whether elevated serum synuclein-gamma levels were of clinical significance as a serological marker in cancer diagnosis and monitoring. METHODOLOGY: Pre-treatment serum synuclein-gamma levels of patients with gastrointestinal and esophageal squamous cell carcinomas, benign disease and healthy controls were analyzed by a specific sandwich ELISA for synuclein-gamma. RESULTS: Statistically significant differences in serum synuclein-gamma levels between patients with colo rectal cancer, gastric adenocarcinomas, esophageal cancer and healthy individuals were observed (p<0.001). When a cut-off value for synuclein-gamma was determined at ≥4 ng/mL by receiver operating characteristic curves, sensitivity and specificity were 16.4% and 97.7% in colorectal cancer, 23.0% and 99.3% in gastric adenocarcinomas, and 19.5% and 98.7% in esophageal cancer, respectively. Compared with carcinoembryonic antigen and carbohydrate antigen 19-9, synuclein-gamma was more sensitive in early detection of colorectal cancer (17.3% vs. 9.6% and 7.5%), gastric adenocarcinomas (20.6% vs. 0% and 3.2%) and esophageal cancer (22.2% vs. 3.4% and 0%), respectively. A combined analysis of the above markers yielded incremental positive rates compared with anyone alone. CONCLUSIONS: These results indicated that serum synuclein-gamma provided a promising diagnostic biomarker for early detection and was a complementary biomarker of carcinoembryonic antigen and/or CA19-9 in gastrointestinal and esophageal cancer.