nsc-74859 and Pancreatic-Neoplasms

Pancreatic stellate cells (PSCs) play a pivotal role in pancreatic fibrosis, a characteristic feature of pancreatic cancer. Although it is still controversial, previous studies have suggested that PSCs promote the progression of pancreatic cancer by regulating the cell functions of cancer cells. PSCs produce large amounts of IL-6, which promotes the accumulation of myeloid-derived suppressor cells via a signal transducers and activator of transcription 3 (STAT3)-dependent mechanism. But the role of IL-6/STAT3 pathway in the interaction between PSCs and pancreatic cancer cells remains largely unknown.. To clarify the role of IL-6/STAT3 in the interaction between PSCs and cancer cells.. Human pancreatic cancer cells (Panc-1 and SUIT-2 cells) were treated with conditioned medium of immortalized human PSCs (PSC-CM). The effects of PSC-CM and IL-6 neutralization on the mRNA expression profiles were examined using Agilent's microarray. Activation of STAT3 was assessed by Western blotting using an anti-phospho-specific antibody. Cellular migration was examined by a two-chamber assay. The expression of markers related to epithelial-mesenchymal transition (EMT) was assessed by real-time reverse transcription PCR.. PSC-CM induced the activation of STAT3 in pancreatic cancer cells. Neutralization of IL-6 suppressed the PSC-CM-induced upregulation of genes including complement factor B, lipocalin, and chemokine (C-C motif) ligand 20. Inhibition of IL-6/STAT3 pathway by anti-IL-6 antibody or a STAT3 inhibitor (NSC74859) inhibited the PSC-CM-induced migration and the expression of EMT-related markers (Snail and cadherin-2) in pancreatic cancer cells.. IL-6/STAT3 pathway regulates the PSC-induced EMT and alterations in gene expression in pancreatic cancer cells.

Topics: Aminosalicylic Acids; Antibodies, Neutralizing; Benzenesulfonates; Cell Line, Tumor; Epithelial-Mesenchymal Transition; Fibroblasts; Gene Expression Regulation; Humans; Interleukin-6; Pancreatic Neoplasms; Pancreatic Stellate Cells; Signal Transduction; STAT3 Transcription Factor

Pancreatic cancer is a largely incurable disease, and increasing evidence supports strategies targeting multiple molecular mediators of critical functions of pancreatic ductal adenocarcinoma cells. Intracellular redox state modulates the activity of various signal transduction pathways and biological processes, including cell survival, drug resistance and responsiveness to microenvironmental factors. Recently, it has been shown that the transcription factor STAT3 is under redox control, but the mechanisms involved in its regulation are unknown. Here, we demonstrate for the first time that STAT3 DNA binding and transcriptional activity is directly regulated by the redox function of the APE1/Ref-1 endonuclease, using overexpression and redox-specific mutational strategies, and gene knockdown. Also, pharmacological blockade of APE1/Ref-1 by the redox-selective inhibitor E3330 abrogates STAT3 DNA binding. Since APE1/Ref-1 also exerts redox control on other cancer-associated transcription factors, we assessed the impact of dual-targeting of STAT3 signaling and APE1/Ref-1 redox on pancreatic cancer cell functions. We observed that disruption of APE1/Ref-1 redox activity synergizes with STAT3 blockade to potently inhibit the proliferation and viability of human PDAC cells. Mechanistically, we show that STAT3-APE1/Ref-1 dual targeting promotes marked tumor cell apoptosis, with engagement of caspase-3 signaling, which are significantly increased in comparison to the effects triggered by single target blockade. Also, we show that STAT3-APE1/Ref-1 dual blockade results in significant inhibition of tumor cell migration. Overall, this work demonstrates that the transcriptional activity of STAT3 is directly regulated by the redox function of APE1/Ref-1, and that concurrent blockade of STAT3 and APE1/Ref-1 redox synergize effectively inhibit critical PDAC cell functions.

Topics: Adenocarcinoma; Aminosalicylic Acids; Apoptosis; Benzenesulfonates; Benzoquinones; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cyclic S-Oxides; DNA-(Apurinic or Apyrimidinic Site) Lyase; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Molecular Targeted Therapy; Oxidation-Reduction; Pancreatic Neoplasms; Propionates; RNA, Small Interfering; Signal Transduction; STAT3 Transcription Factor; Transcription, Genetic

The molecular modeling of the phosphotyrosine (pTyr)-SH2 domain interaction in the Stat3:Stat3 dimerization, combined with in silico structural analysis of the Stat3 dimerization disruptor, S3I-201, has furnished a diverse set of analogs. We present evidence from in vitro biochemical and biophysical studies that the structural analog, S3I-201.1066 directly interacts with Stat3 or the SH2 domain, with an affinity (K(D)) of 2.74microM, and disrupts the binding of Stat3 to the cognate pTyr-peptide, GpYLPQTV-NH(2), with an IC(50) of 23microM. Moreover, S3I-201.1066 selectively blocks the association of Stat3 with the epidermal growth factor receptor (EGFR), and inhibits Stat3 tyrosine phosphorylation and nuclear translocation in EGF-stimulated mouse fibroblasts. In cancer cells that harbor aberrant Stat3 activity, S3I-201.1066 inhibits constitutive Stat3 DNA-binding and transcriptional activities. By contrast, S3I-201.1066 has no effect on Src activation or the EGFR-mediated activation of the Erk1/2(MAPK) pathway. S3I-201.1066 selectively suppresses the viability, survival, and malignant transformation of the human breast and pancreatic cancer lines and the v-Src-transformed mouse fibroblasts harboring persistently active Stat3. Treatment with S3I-201.1066 of malignant cells harboring aberrantly active Stat3 down-regulated the expression of c-Myc, Bcl-xL, Survivin, the matrix metalloproteinase 9, and VEGF. The in vivo administration of S3I-201.1066-induced significant antitumor response in mouse models of human breast cancer, which correlates with the inhibition of constitutively active Stat3 and the suppression of known Stat3-regulated genes. Our studies identify a novel small-molecule that binds with a high affinity to Stat3, blocks Stat3 activation and function, and thereby induces antitumor response in human breast tumor xenografts harboring persistently active Stat3.

Topics: Aminosalicylic Acids; Animals; Benzenesulfonates; Breast Neoplasms; Cell Line; Cell Line, Tumor; Cell Transformation, Neoplastic; DNA, Neoplasm; ErbB Receptors; Female; Fluorescence Polarization Immunoassay; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Nude; Pancreatic Neoplasms; src Homology Domains; STAT3 Transcription Factor; Surface Plasmon Resonance; Transcriptional Activation