Defective N-glycosylation of IL6 induces metastasis and tyrosine kinase inhibitor resistance in lung cancer.

The IL6-GP130-STAT3 pathway facilitates lung cancer progression and resistance to tyrosine kinase inhibitors. Although glycosylation alters the stability of GP130, its effect on the ligand IL6 remains unclear. We herein find that N-glycosylated IL6, especially at Asn73, primarily stimulates JAK-STAT3 signaling and prolongs STAT3 phosphorylation, whereas N-glycosylation-defective IL6 (deNG-IL6) induces shortened STAT3 activation and alters the downstream signaling preference for the SRC-YAP-SOX2 axis.

Upregulation of tissue factor by activated Stat3 contributes to malignant pleural effusion generation via enhancing tumor metastasis and vascular permeability in lung adenocarcinoma.

Malignant pleural effusion (MPE) is a poor prognostic sign for patients with lung cancer. Tissue factor (TF) is a coagulation factor that participates in angiogenesis and vascular permeability and is abundant in MPE. We previously demonstrated that autocrine IL-6-activated Stat3 contributes to tumor metastasis and upregulation of VEGF, resulting in the generation of MPE in lung adenocarcinoma.

Metformin enhances cisplatin cytotoxicity by suppressing signal transducer and activator of transcription-3 activity independently of the liver kinase B1-AMP-activated protein kinase pathway.

Metformin has been used as first-line treatment in patients with type 2 diabetes, and is reported to reduce cancer risk and progression by activating the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Cisplatin remains the main drug for treating advanced non-small-cell lung cancer. However, drug resistance often develops through several mechanisms during the treatment course, including one mechanism mediated by the activation of the IL-6/signal transducer and activator of transcription (STAT)-3 pathway, related to the generation of reactive oxygen species (ROS).

Mitochondrial uncoupling protein 2 regulates the effects of paclitaxel on Stat3 activation and cellular survival in lung cancer cells.

Growing evidence suggests that Stat3 contributes to chemoresistance. However, the impact of chemotherapy on Stat3 activity is unclear. We found that paclitaxel activated Stat3 in the human lung cancer cell lines PC14PE6AS2 (AS2) and H157, whereas it reduced Stat3 activation in A549 and H460 cells.

Activation of the signal transducer and activator of transcription 3 pathway up-regulates estrogen receptor-beta expression in lung adenocarcinoma cells.

Estrogens contribute to the pathogenesis of female lung cancer and function mainly through estrogen receptor-β (ERβ). However, the way in which ERβ expression is regulated in lung cancer cells remains to be explored. We have found that signal transducer and activator of transcription 3 (Stat3) activation up-regulates ERβ expression in PC14PE6/AS2 lung cancer cells in a preliminary Affymetrix oligonucleotide array study, and we sought to confirm the findings.

Transcriptional activation of the Axl and PDGFR-α by c-Met through a ras- and Src-independent mechanism in human bladder cancer.

Background: A cross-talk between different receptor tyrosine kinases (RTKs) plays an important role in the pathogenesis of human cancers.

Methods: Both NIH-Met5 and T24-Met3 cell lines harboring an inducible human c-Met gene were established. C-Met-related RTKs were screened by RTK microarray analysis.

Signal transducer and activator of transcription 3 activation up-regulates interleukin-6 autocrine production: a biochemical and genetic study of established cancer cell lines and clinical isolated human cancer cells.

Background: Spontaneous interleukin-6 (IL-6) production has been observed in various tumors and implicated in the pathogenesis, progression and drug resistance in cancer. However, the regulation of IL-6 autocrine production in cancer cells is not fully understood. IL-6 is auto-regulated in many types of cell.

SUMO-1 overexpression increases RbAp46 protein stability and suppresses cell growth.

The retinoblastoma suppressor (Rb)-associated protein 46 (RbAp46) is a nuclear protein of 46 kDa and contains four repeats that end with Trp-Asp (WD) residues. In this study, we reveal that the RbAp46 protein level upon SUMO-1 expression was increased. The increasing level of RbAp46 protein by SUMO-1 was not regulated at the transcriptional level.

Ha-ras oncogene-induced Stat3 phosphorylation enhances oncogenicity of the cell.

The ras oncogene needs a second factor to induce transformation and tumorigenicity of the cell. In this study, we show that mouse fibroblast 7-4-Stat3C cells overexpressing both Ha-ras(val12) oncogene and active-form Stat3 (Stat3C) showed higher colony formation in soft agar and xenograft tumor growth in BALB/c mice. Further studies show that both serine-727 and tyrosine-705 of Stat3 were phosphorylated while Ha-ras was overexpressed.

HER-2/neu raises SHP-2, stops IFN-gamma anti-proliferation in bladder cancer.

Gene amplification or HER-2/neu protein overexpression signals a poor outcome for bladder cancer patients. We investigated the anti-proliferative effect of IFN-gamma in HER-2/neu-transfected human bladder cancer cells (TCC-N5 and TCC-N10). The cells continued growing after IFN-gamma stimulation but did not activate the Janus kinase (Jak)/Stat pathway.

Cell confluence-induced activation of signal transducer and activator of transcription-3 (Stat3) triggers epithelial dome formation via augmentation of sodium hydrogen exchanger-3 (NHE3) expression.

Cell confluence induces the activation of signal transducer and activator of transcription-3 (Stat3) in various cancer and epithelial cells, yet the biological implications and the associated regulatory mechanisms remain unclear. Because confluent polarized epithelia demonstrate dome formation and sodium influx that mimic the onset of differentiation, we sought to elucidate the role of Stat3 in association with the regulation of selective epithelial transporters in this biological phenomenon. This study established the correlation between Stat3 activation and cell confluence-induced dome formation in Madin-Darby canine kidney cells (MDCK) by following Stat3 activation events in dome-forming cells.