Implication of STAT3 Signaling in Human Colonic Cancer Cells during Intestinal Trefoil Factor 3 (TFF3) – and Vascular Endothelial Growth Factor–Mediated Cellular Invasion and Tumor Growth

Abstract

Signal transducer and activator of transcription (STAT) 3 is overexpressed or activated in most types of human tumors and has been classified as an oncogene. In the present study, we investigated the contribution of the STAT3s to the proinvasive activity of trefoil factors (TFF) and vascular endothelial growth factor (VEGF) in human colorectal cancer cells HCT8/S11 expressing VEGF receptors. Both intestinal trefoil peptide (TFF3) and VEGF, but not pS2 (TFF1), activate STAT3 signaling through Tyr705 phosphorylation of both STAT3α and STAT3β isoforms. Blockade of STAT3 signaling by STAT3β, depletion of the STAT3α/β isoforms by RNA interference, and pharmacologic inhibition of STAT3α/β phosphorylation by cucurbitacin or STAT3 inhibitory peptide abrogates TFF- and VEGF-induced cellular invasion and reduces the growth of HCT8/S11 tumor xenografts in athymic mice. Differential gene expression analysis using DNA microarrays revealed that overexpression of STAT3β down-regulates the VEGF receptors Flt-1, neuropilins 1 and 2, and the inhibitor of DNA binding/differentiation (Id-2) gene product involved in the neoplastic transformation. Taken together, our data suggest that TFF3 and the essential tumor angiogenesis regulator VEGF165 exert potent proinvasive activity through STAT3 signaling in human colorectal cancer cells. We also validate new therapeutic strategies targeting STAT3 signaling by pharmacologic inhibitors and RNA interference for the treatment of colorectal cancer patients.

Monomerization of Homodimeric Trefoil Factor 3 (TFF3) by an Aminonitrile Compound Inhibits TFF3-Dependent Cancer Cell Survival

“…It is demonstrated herein that monomeric TFF3 reduces cell viability and the generation of monomeric TFF3 by AMPC also antagonized the homodimeric TFF3 stimulation of cell survival (Figure ). The antagonistic effect of TFF3 monomers has also been reported previously in various models ,,,, and is consistent with dimeric or dimerizing ligand interactions responsible for receptor activation and downstream signaling events. ,− One advantage of this approach of using a small molecule to generate a biologic antagonist (monomeric TFF3) is that AMPC would only generate TFF3 monomers at sites of TFF3 expression, such as occurs in various carcinomas. − This effect would presumably generate high concentrations of the monomer within the tumor mass, thereby improving targeting specificity. Furthermore, generation of TFF3 monomer within the cancer would inhibit both autocrine effects of TFF3 and paracrine interactions with the tumor microenvironment.…”

“…As an example, TFF3 binding to LINGO2 prevents LINGO2 repression of EGFR (HER1) signaling . In addition, TFF3 has also been reported to enhance the activation of multiple other receptor and cytoplasmic kinase pathways including HER2–4, MET, IGF-1R, and SRC and hence promotes the downstream activity of p44/42 MAPK, NF-κB, PI3K-AKT, and STAT3. ,− Consequently, TFF3 potently promotes cancer cell survival, − anchorage independent growth, migration, invasion, cancer stem cell-like behavior ,, and tumor angiogenesis, growth, and metastasis in vivo . ,,, Furthermore, TFF3 decreases the sensitivity of various carcinomas to ionizing radiation and chemo- and targeted-therapeutics ,,,, and mediates acquired resistance to the same. Hence, TFF3 constitutes a validated target in oncology and is a potent driver of oncogenic progression.…”

Prognostic Value of Trefoil Factor 3 Expression in Patients with Gastric Cancer

“…A few previous studies have indicated that TFF3 is associated with oncogenic potential, including roles in cell proliferation, apoptosis, motility, invasion [24], response to chemotherapy [25], and angiogenesis [6, 26]. STAT3 is usually overexpressed in various types of human malignancies, and its signaling to exert the invasive ability may be activated by TFF3 [27]. Our study results also supported that TFF3 might be associated with activation of STAT3 in gastric cancer cells.…”

Pathological and therapeutic roles of bioactive peptide trefoil factor 3 in diverse diseases: recent progress and perspective

“…Furthermore, the promoter region of TFF3 contains binding sites for STAT3, which enables self-induction of TFF3 [85]. STAT3 inhibition has been consistently shown to hinder the proliferation, invasion, and survival of TFF3-induced cancer cells [66,[86][87][88][89].…”