Computer-aided lead optimization derives a unique, orally bioavailable inhibitor of the signal transducer and activator of transcription (Stat)3 Src homology 2 domain. BP-1-102 binds Stat3 with an affinity ( K D ) of 504 nM, blocks Stat3–phospho-tyrosine (pTyr) peptide interactions and Stat3 activation at 4–6.8 μM, and selectively inhibits growth, survival, migration, and invasion of Stat3-dependent tumor cells. BP-1-102–mediated inhibition of aberrantly active Stat3 in tumor cells suppresses the expression of c-Myc, Cyclin D1, Bcl-xL, Survivin, VEGF, and Krüppel-like factor 8, which is identified as a Stat3 target gene that promotes Stat3-mediated breast tumor cell migration and invasion. Treatment of breast cancer cells with BP-1-102 further blocks Stat3–NF-κB cross-talk, the release of granulocyte colony-stimulating factor, soluble intercellular adhesion molecule 1, macrophage migration-inhibitory factor/glycosylation-inhibiting factor, interleukin 1 receptor antagonist, and serine protease inhibitor protein 1, and the phosphorylation of focal adhesion kinase and paxillin, while enhancing E-cadherin expression. Intravenous or oral gavage delivery of BP-1-102 furnishes micromolar or microgram levels in tumor tissues and inhibits growth of human breast and lung tumor xenografts.

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 (KD) of 2.74 nM, and disrupts the binding of Stat3 to the cognate pTyr-peptide, GpYLPQTV-NH2, with an IC50 of 23 μM. 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 Erk1/2MAPK 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.

Expression of the long noncoding RNA (lncRNA) SPRY4-IT1 is low in normal human melanocytes but high in melanoma cells. siRNA knockdown of SPRY4-IT1 blocks melanoma cell invasion and proliferation, and increases apoptosis. To investigate its function further, we affinity purified SPRY4-IT1 from melanoma cells and used mass spectrometry to identify the protein lipin 2, an enzyme that converts phosphatidate to diacylglycerol (DAG), as a major binding partner. SPRY4-IT1 knockdown increases the accumulation of lipin2 protein and upregulate the expression of diacylglycerol O-acyltransferase 2 (DGAT2) an enzyme involved in the conversion of DAG to triacylglycerol (TAG). When SPRY4-IT1 knockdown and control melanoma cells were subjected to shotgun lipidomics, an MS-based assay that permits the quantification of changes in the cellular lipid profile, we found that SPRY4-IT1 knockdown induced significant changes in a number of lipid species, including increased acyl carnitine, fatty acyl chains, and triacylglycerol (TAG). Together, these results suggest the possibility that SPRY4-IT1 knockdown may induce apoptosis via lipin 2-mediated alterations in lipid metabolism leading to cellular lipotoxicity.

Dysregulation of the epidermal growth factor receptor (EGFR) promotes cancer cell growth, invasion and metastasis. However, its relevant downstream effectors are still limited. Here, we show that EGFR promotes breast tumor growth and metastasis by downregulating the tumor suppressor micoRNA-338-3p (miR-338-3p) and activating the EYA2 (EYA transcriptional coactivator and phosphatase 2) oncoprotein. EGFR represses miR-338-3p expression largely through HIF1α transcription factor. miR-338-3p inhibits EYA2 expression by binding to the 3′-untranslated region of EYA2. EGFR increases EYA2 expression via HIF1α repression of miR-338-3p. Through the miR-338-3p/EYA2 pathway, EGFR increases breast cancer cell growth, epithelial-to-mesenchymal transition, migration, invasion and lung metastasis in vitro and in a allograft tumor mouse model in vivo. In breast cancer patients, miR-338-3p expression negatively correlates with the expression of EGFR and EYA2, EGFR status positively associates with EYA2 expression, and miR-338-3p and EYA2 predict breast cancer lung metastasis when expressed in primary breast cancers. These data suggest that the miR-338-3p/ EYA2 axis contributes to EGFR-mediated tumor growth and lung metastasis and that miR-338-3p activation or EYA2 inhibition or combination therapy targeting EGFR/miR-338-3p/EYA2 axis may be a promising way to treat patients with metastatic cancer. Cell Death and Disease (2017) 8, e2928; doi:10.1038/cddis.2017.325; published online 13 July 2017The epidermal growth factor receptor (EGFR) is a member of the ErbB (avian erythroblastosis oncogene B) family of receptors and activates multiple signaling pathways, including mitogen-activated protein kinase (MAPK)/extracellular signalregulated kinases (ERK) and phosphoinositide-3-kinase (PI3K)/V-AKT murine thymoma viral oncogene homolog (AKT) pathways. 1-3 EGFR activation regulates many biological processes, such as cell proliferation, invasion, metastasis and apoptosis. [4][5][6] EGFR is overexpressed in various human cancers, including lung cancer, breast cancer, colon cancer and glioblastoma, and is associated with tumor malignancy and poor prognosis. 7-10 Thus, EGFR and its downstream signaling effectors have become targets for cancer therapy. 11 Approximately 90% of deaths associated with cancer are due to distant metastases. 12 Many cancers can metastasize anywhere in body but primarily metastasizes to some organs or tissues. For instance, lungs and bones are frequent sites of breast cancer metastasis. Although EGFR dysregulation enhances cancer metastasis, the relevant downstream effectors are largely unknown.MicroRNAs (miRNAs) are small noncoding RNA molecules (about 22 nucleotides in length), which function in RNA silencing and post-transcriptional regulation of gene expression. miRNAs participate in many biological processes, such as cell proliferation, invasion, metastasis, and apoptosis. 13 Recently, EGFR has been shown to promote prostate cancer bone metastasis by decreasing the expression of miR-1, a tumor suppressor, and inc...

Sorafenib, a novel drug for metastatic renal cancer, has broadspectrum activity against multiple tyrosine kinases, including Raf-1, vascular endothelial growth factor receptor and plateletderived growth factor receptor. However, little is known about its effects on the immune system. In this report, we examine the effects of sorafenib on the proliferation and activation of human peripheral blood T cells, as well as its effects on T-cell-mediated immune response in mice. At concentrations similar to those used in patients, sorafenib inhibited the proliferation of primary human T cells in vitro. At more than 10 lM, sorafenib caused an irrecoverable inhibition of proliferation, even after drug withdrawal. In addition, sorafenib induced T-cell apoptosis at concentrations higher than 10 lM. sorafenib also caused G 0 /G 1 phase arrest, inhibition of CD25 and CD69 expression, interleukin-2 production and LCK phosphorylation in the T cells; all of these effects exhibited dose and time dependence. When tested against contact dermatitis in mice, sorafenib significantly reduced the ear swelling induced by picryl chloride. These findings suggest that sorafenib may cause the loss of T-cell immune response by inducing apoptosis and targeting LCK. This could potentially lead to immunosuppression in patients with cancer.

Signal transducer and activator of transcription 3 (Stat3) protein is a cytosolic transcription factor that relays signals from receptors in the plasma membrane directly to the nucleus, and is routinely hyperactivated in many human cancers and diseases. [1] Regarded as an oncogene, Stat3 is well-recognized as a master regulator of cellular events that lead to the cancer phenotype, making this protein viable target for molecular therapeutic design. [2] Stat3 inhibitors have included peptides, [3][4] peptidomimetics, [5][6][7][8][9] small molecules [10][11][12][13][14] and metal complexes.[15] Despite significant advances in Stat3 inhibition, [1] truly potent (in vivo), isoform-selective, small molecule Stat3 agents have not been readily forthcoming; this is likely due in part to the challenge of disrupting protein-protein interactions. [16] The canonical view of Stat3 signaling describes inactive Stat3 monomers located predominantly within the cytoplasm. The Stat3 activation pathway begins with a cytokine or growth factor ligand interaction with the extracellular domain of a transmembrane receptor. Subsequently, receptor-associated tyrosine kinases such as the Janus kinases (Jaks) are induced to phosphorylate tyrosine residues on the specific receptor's cytoplasmic domain. These phosphorylated residues then serve to recruit latent Stat monomers through interaction with their SH2 domains. Tyrosine-kinase-mediated phosphorylation of Tyr705 on Stat3 monomers induces Stat3-receptor dissociation and Stat3-Stat3 homodimerization through reciprocal phosphotyrosine (pTyr)-SH2 domain interactions. The resulting transcriptionally active Stat3 dimers then translocate to the nucleus, where they bind to specific DNAresponse elements in the promoters of target genes and induce antiapoptotic gene expression programs (e.g., Bcl-x L ) and the overexpression of cell cycle regulators (for example, cyclin D 1 ).[17] Current programs of research, including our own, have focused on inhibiting the Correspondence to: Patrick T. Gunning, patrick.gunning@utoronto.ca. NIH Public Access Author ManuscriptChembiochem. Author manuscript; available in PMC 2010 August 10. Figure 1A; IC 50 = 86 μM) through in silico structure-based virtual screening of National Cancer Institute chemical libraries.[12] We sought to optimize lead agent S3I-201 through rational, synthetic modifications with the global objective of obtaining isoform-selective, Stat3 inhibitors displaying potency at low to submicromolar concentrations. S3I-201 is based on a glycolic acid scaffold whose carboxylic acid functionality has been condensed with 4-aminosalicylic acid to furnish the amide bond, and whose hydroxyl has been tosylated ( Figure 1A). The Stat3 SH2 domain is broadly composed of three subpockets, but GOLD [18] docking studies showed that S3I-201 can access only two of these subpockets simultaneously ( Figure 1B), and this identified a potential means of improving inhibitor potency. The salicylic (ortho-hydroxybenzoic) acid component of S3I-201 is a known pTyr ...

Liquid biopsy has provided an efficient way for detection of gene alterations in advanced non‐small‐cell lung cancer (NSCLC). However, the correlation between systematic determination of somatic genomic alterations in liquid biopsy and tumor biopsy still remained unclear, and the concordance rate between cell‐free DNA (cfDNA) and matched tumor tissue DNA needs to be increased. A prospective study was performed to detect differences in genetic profiles of cfDNA in sputum, plasma, urine, and tumor tissue from 50 advanced NSCLC patients in parallel by the same next‐generation sequencing (NGS) platform. Driver genes alterations were identified in cfDNA sample and matched tumor sample, with an overall concordance rate of 86% in plasma cfDNA, 74% in sputum cfDNA, 70% in urine cfDNA, and 90% in cfDNA of combination of plasma, sputum, and urine. And the concordant rate of cfDNA in sputum in patients with smoking history was higher than that in patients without history of smoking (89% vs. 66%, P = 0.033) and equal to that in plasma cfDNA of the smoking patients (89% vs. 89%). In conclusion, sputum cfDNA can be considered as an alternative medium to liquid biopsy, while the complementarity of genomic profiles in cfDNA among plasma, sputum, and urine was beneficial to detect more diver genes alterations and improve the utility of liquid biopsy in advanced NSCLC (Liquid Biopsy for Detection of Driver Mutation in NSCLC; NCT02778854).

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