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TrkA Interacts with and Phosphorylates STAT3 to Enhance Gene Transcription and Promote Breast Cancer Stem Cells in Triple-Negative and HER2-Enriched Breast Cancers.

ABSTRACT: JAK2-STAT3 and TrkA signaling pathways have been separately implicated in aggressive breast cancers; however, whether they are co-activated or undergo functional interaction has not been thoroughly investigated. Herein we report, for the first time that STAT3 and TrkA are significantly co-overexpressed and co-activated in triple-negative breast cancer (TNBC) and HER2-enriched breast cancer, as shown by immunohistochemical staining and data mining. Through immunofluorescence staining-confocal microscopy and immunoprecipitation-Western blotting, we found that TrkA and STAT3 co-localize and physically interact in the cytoplasm, and the interaction is dependent on STAT3-Y705 phosphorylation. TrkA-STAT3 interaction leads to STAT3 phosphorylation at Y705 by TrkA in breast cancer cells and cell-free kinase assays, indicating that STAT3 is a novel substrate of TrkA. β-NGF-mediated TrkA activation induces TrkA-STAT3 interaction, STAT3 nuclear transport and transcriptional activity, and the expression of STAT3 target genes, SOX2 and MYC. The co-activation of both pathways promotes breast cancer stem cells. Finally, we found that TNBC and HER2-enriched breast cancer with JAK2-STAT3 and TrkA co-activation are positively associated with poor overall metastasis-free and organ-specific metastasis-free survival. Collectively, our study uncovered that TrkA is a novel activating kinase of STAT3, and their co-activation enhances gene transcription and promotes breast cancer stem cells in TNBC and HER2-enriched breast cancer.

SUBMITTER: Regua AT

PROVIDER: S-EPMC8150921 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Signal transducer and activator of transcription 3 (STAT3), glioma oncogene homolog 1 (GLI1), and truncated GLI1 (tGLI1) are oncogenic transcription factors playing important roles in breast cancer. tGLI1 is a gain-of-function GLI1 isoform. Whether STAT3 physically and/or functionally interacts with GLI1/tGLI1 has not been explored. To address this knowledge gap, we analyzed 47 node-positive breast cancer specimens using immunohistochemical staining and found that phosphorylated-STAT3 (Y705), GLI1, and tGLI1 are co-overexpressed in the majority of triple-negative breast carcinomas (64%) and HER2-enriched (68%) breast carcinomas, and in lymph node metastases (65%). Using gene set enrichment analysis, we analyzed 710 breast tumors and found that STAT3 activation and GLI1/tGLI1 activation signatures are co-enriched in triple-negative subtypes of breast cancers and HER2-enriched subtypes of breast cancers, but not in luminal subtypes of breast cancers. Patients with high levels of STAT3 and GLI1/tGLI1 co-activation in their breast tumors had worse metastasis-free survival compared to those with low levels. Since these proteins co-overexpress in breast tumors, we examined whether they form complexes and observed that STAT3 interacted with both GLI1 and tGLI1. We further found that the STAT3-GLI1 and STAT3-tGLI1 complexes bind to both consensus GLI1-binding and STAT3-binding sites using chromatin immunoprecipitation (ChIP) assay, and that the co-overexpression markedly activated a promoter controlled by GLI1-binding sites. To identify genes that can be directly co-activated by STAT3 and GLI1/tGLI1, we analyzed three ChIP-seq datasets and identified 34 potential target genes. Following validations using reverse transcription polymerase chain reaction and survival analysis, we identified three genes as novel transcriptional targets of STAT3 and GLI1/tGLI1, R-Ras2, Cep70, and UPF3A. Finally, we observed that co-overexpression of STAT3 with GLI1/tGLI1 promoted the ability of breast cancer cells to form mammospheres and that STAT3 only cooperates with tGLI1 in immortalized mammary epithelial cells. In summary, our study identified novel physical and functional cooperation between two families of oncogenic transcription factors, and the interaction contributes to aggressiveness of breast cancer cells and poor prognosis of triple-negative breast cancers and HER2-enriched breast cancers.

Project description:INTRODUCTION: In general, genomic signatures of breast cancer subtypes have little or no overlap owing to the heterogeneous genetic backgrounds of study samples. Thus, obtaining a reliable signature in the context of isogenic nature of the cells has been challenging and the precise contribution of isogenic triple negative breast cancer (TNBC) versus non-TNBC remains poorly defined. METHODS: We established isogenic stable cell lines representing TNBC and Human Epidermal Growth Factor Receptor 2 positive (HER2+) breast cancers by introducing HER2 in TNBC cell lines MDA-MB-231 and MDA-MB-468. We examined protein level expression and functionality of the transfected receptor by treatment with an antagonist of HER2. Using microarray profiling, we obtained a comprehensive gene list of differentially expressed between TNBC and HER2+ clones. We identified and validated underlying isogenic components using qPCR and also compared results with expression data from patients with similar breast cancer subtypes. RESULTS: We identified 544 and 1087 statistically significant differentially expressed genes between isogenic TNBC and HER2+ samples in MDA-MB-231 and MDA-MB-468 backgrounds respectively and a shared signature of 49 genes. By comparing results from MDA-MB-231 and MDA-MB-468 backgrounds with two patient microarray datasets, we identified 17 and 22 common genes with same expression trend respectively. Additionally, we identified 56 and 78 genes from MDA-MB-231 and MDA-MB-468 comparisons respectively present in our published RNA-seq data. CONCLUSIONS: Using our unique model system, we have identified an isogenic gene expression signature between TNBC and HER2+ breast cancer. A portion of our results was also verified in patient data samples, indicating an existence of isogenic element associated with HER2 status between genetically heterogeneous breast cancer samples. These findings may potentially contribute to the development of molecular platform that would be valuable for diagnostic and therapeutic decision for TNBC and in distinguishing it from HER2+ subtype.

Project description:BackgroundIdentification of HER2-positive breast cancers with high anti-HER2 sensitivity could help de-escalate chemotherapy. Here, we tested a clinically applicable RNA-based assay that combines ERBB2 and the HER2-enriched (HER2-E) intrinsic subtype in HER2-positive disease treated with dual HER2-blockade without chemotherapy.MethodsA research-based PAM50 assay was applied in 422 HER2-positive tumors from five II-III clinical trials (SOLTI-PAMELA, TBCRC023, TBCRC006, PER-ELISA, EGF104090). In SOLTI-PAMELA, TBCRC023, TBCRC006, and PER-ELISA, all patients had early disease and were treated with neoadjuvant lapatinib or pertuzumab plus trastuzumab for 12-24 weeks. Primary outcome was pathological complete response (pCR). In EGF104900, 296 women with advanced disease were randomized to receive either lapatinib alone or lapatinib plus trastuzumab. Progression-free survival (PFS), overall response rate (ORR), and overall survival (OS) were evaluated.ResultsA total of 305 patients with early and 117 patients with advanced HER2-positive disease were analyzed. In early disease, HER2-E represented 83.8% and 44.7% of ERBB2-high and ERBB2-low tumors, respectively. Following lapatinib and trastuzumab, the HER2-E and ERBB2 (HER2-E/ERBB2)-high group showed a higher pCR rate compared to the rest (44.5%, 95% confidence interval [CI] = 35.4% to 53.9% vs 11.6%, 95% CI = 6.9% to 18.0%; adjusted odds ratio [OR] = 6.05, 95% CI = 3.10 to 11.80, P < .001). Similar findings were observed with neoadjuvant trastuzumab and pertuzumab (pCR rate of 66.7% in HER2-E/ERBB2-high, 95% CI = 22.3% to 95.7% vs 14.7% in others, 95% CI = 4.9% to 31.1%; adjusted OR = 11.60, 95% CI = 1.66 to 81.10, P = .01). In the advanced setting, the HER2-E/ERBB2-high group was independently associated with longer PFS (hazard ratio [HR] = 0.52, 95% CI = 0.35 to 0.79, P < .001); higher ORR (16.3%, 95% CI = 8.9% to 26.2% vs 3.7%, 95% CI = 0.8% to 10.3%, P = .02); and longer OS (HR = 0.66, 95% CI = 0.44 to 0.97, P = .01).ConclusionsCombining HER2-E subtype and ERBB2 mRNA into a single assay identifies tumors with high responsiveness to HER2-targeted therapy. This biomarker could help de-escalate chemotherapy in approximately 40% of patients with HER2-positive breast cancer.

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TrkA Interacts with and Phosphorylates STAT3 to Enhance Gene Transcription and Promote Breast Cancer Stem Cells in Triple-Negative and HER2-Enriched Breast Cancers.

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