ESE-1 Knockdown Attenuates Growth in Trastuzumab-resistant HER2+ Breast Cancer Cells

E74-like factor 3 suppresses microRNA-485-5p transcription to trigger growth and metastasis of ovarian cancer cells with the involvement of CLDN4/Wnt/β-catenin axis

Ovarian cancer (OC) is one of the most prevailing gynecological malignancies with high mortality rate, while E74 like ETS transcription factor 3 (ELF3) is reported to be associated with tumorigenesis. This work aims to analyze the role of ELF3 on the suppression of miR-485-5p transcription in OC. Expression of ELF3 in OC and its correlation with overall survival were predicted on a bioinformation system GEPIA. Then, the level of ELF3 in OC tissues and cells and in normal ones was evaluated. Binding relationships between ELF3 and microRNA (miR)-485-5p, and between miR-485-5p and claudin-4 (CLND4) were predicted through Bioinformatics tools. Altered expression of ELF3, miR-485-5p and CLND4 was introduced alone or jointly to probe their influences on OC cell growth. ELF3 was suggested to be highly expressed in OC, which was linked to poor prognosis in patients. Abundant expression of ELF3 was identified in OC tissues and cell lines as relative to the normal ones. ELF3 inhibition suppressed growth and metastasis of OC cells. ELF3 transcriptionally suppressed miR-485-5p expression to further enhance CLDN4 expression. Overexpression of miR-485-5p led to similar trends as ELF3 inhibition did. Importantly, upregulation of CLDN4 was found to block the roles of ELF3 inhibition in OC cells. In addition, the Wnt/signaling pathway suppressed by miR-485-5p mimic was reactivated following CLDN4 overexpression. This study evidenced that ELF3 suppresses miR-485-5p transcription to enhance CLDN4 expression, leading to Wnt/β-catenin activation and promoting OC cell growth and metastasis. This work may provide new ideas for gene-based therapies for OC.

Evaluation of the Insulin-like Growth Factor Receptor Pathway in Patients with Advanced Breast Cancer Treated with Trastuzumab

BACKGROUND

Trastuzumab is a monoclonal antibody against HER2-positive breast cancer. Despite improving the natural history of the disease, there is a number of patients who are resistant to it, whereas all patients will eventually develop resistance and disease will progress. Inconsistent preclinical data show that the IGF-R pathway may contribute to either de novo or acquired resistance to trastuzumab.

MATERIALS AND METHODS

In total, 227 trastuzumab-treated metastatic breast cancer patients were evaluated for IGF-1, IGF-1R, GLP-1R, Akt1, Akt2 Akt3 mRNA expression, and IGF-1Rα, IGF-1Rβ, IGF-2R protein expression.

RESULTS

Only 139 patients were truly HER2-positive by central assessment. Among HER2-positive patients, high Akt2 and GLP-1R mRNA expression showed a trend towards higher and lower risk of progression, respectively (HR=1.83, 95%CI=0.90-3.72, p=0.094 and HR=0.62, 95%CI=0.36-1.06, p=0.079), while high Akt1 and GLP-1R mRNA expression presented a trend towards unfavorable survival (HR=1.67, 95%CI=0.93-2.99, p=0.086 and HR=1.67, 95%CI=0.94-2.96, p=0.080). Among HER2-negative patients, high GLP-1R mRNA expression and negative stromal IGF-1Rβ protein expression showed a trend towards worse survival (HR=2.31, 95%CI=0.87-6.13, p=0.094 and HR=2.03, 95%CI=0.94-4.35, p=0.071, respectively). In the multivariate analyses, HER2-positive patients with high Akt1 and GLP-1R mRNA expression had a worse survival (HR=1.86, 95%CI=1.01-3.43, p=0.045 and HR=1.83, 95%CI=0.99-3.41, p=0.055, respectively).

CONCLUSION

This study revealed a crosstalk between the IGF-R pathway and HER2. There was evidence that high Akt1 and GLP-1R mRNA expression might affect survival among HER2-positive metastatic breast cancer patients treated with trastuzumab.

ELF3, ELF5, EHF and SPDEF Transcription Factors in Tissue Homeostasis and Cancer

The epithelium-specific ETS (ESE) transcription factors (ELF3, ELF5, EHF and SPDEF) are defined by their highly conserved ETS DNA binding domain and predominant epithelial-specific expression profile. ESE transcription factors maintain normal cell homeostasis and differentiation of a number of epithelial tissues, and their genetic alteration and deregulated expression has been linked to the progression of several epithelial cancers. Herein we review the normal function of the ESE transcription factors, the mechanisms by which they are dysregulated in cancers, and the current evidence for their role in cancer progression. Finally, we discuss potential therapeutic strategies for targeting or reactivating these factors as a novel means of cancer treatment.

LMO4 mediates trastuzumab resistance in HER2 positive breast cancer cells

Breast cancer is the leading cause of cancer-related mortality in women worldwide. Trastuzumab (Herceptin) is an effective antibody drug for HER2 positive breast cancer; de novo or acquired trastuzumab resistance retarded the use of trastuzumab for at least 70% of HER2 positive breast cancers. In this study, we reported LMO4 (a member of LIM-only proteins) promoted trastuzumab resistance in human breast cancer cells. Over-expression of LMO4 was observed in acquired trastuzumab resistance breast cancer cells SKBR3 HR and BT474 HR. Depletion of LMO4 partly abolished the trastuzumab resistance of SKBR3 HR and BT474 HR cells. Forced expression of LMO4 significantly increased trastuzumab resistance of HER2 positive breast cancer cells both in vitro and in vivo. BCL-2 was regulated by LMO4 and mediated the promoting role of LMO4 in trastuzumab resistance of HER2 positive breast cancer cells. High level of LMO4 was associated with worse clinicopathological parameters (including tumor size and histological grade) and lower survival rate in HER2 positive breast cancer patients. LMO4 therefore could be used as a target to develop diagnostic and therapeutic methods for human HER2 positive breast cancer.