CDK12 Promotes Breast Cancer Progression and Maintains Stemness by Activating c-myc/β -catenin Signaling

2020 ◽  
Vol 20 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Fang Peng ◽  
Chuansheng Yang ◽  
Yanan Kong ◽  
Xiaojia Huang ◽  
Yanyu Chen ◽  
...  

Background: CDK12 is a promising therapeutic target in breast cancer with an effective ability of maintaining cancer cell stemness. Objective: We aim to investigate the mechanism of CDK12 in maintaining breast cancer stemness. Methods: CDK12 expression level was accessed by using RT-qPCR and IHC. CDK12-altered breast cancer cell lines MDA-MB-231-shCDK12 and SkBr-3-CDK12 were then established. CCK8, colony formation assays, and xenograft model were used to value the effect of CDK12 on tumorigenicity. Transwell assay, mammosphere formation, FACS, and lung metastasis model in vivo were determined. Western blot further characterized the mechanism of CDK12 in breast cancer stemness through the c-myc/β-catenin pathway. Results: Our results showed a higher level of CDK12 exhibited in breast cancer samples. Tumor formation, cancer cell mobility, spheroid forming, and the epithelial-mesenchymal transition will be enhanced in the CDK12high group. In addition, CDK12 was associated with lung metastasis and maintained breast cancer cell stemness. CDK12high cancer cells presented higher tumorigenicity and a population of CD44+ subset compared with CDK12low cells. Our study demonstrated c-myc positively expressed with CDK12. The c-myc/β-catenin signaling was activated by CDK12, which is a potential mechanism to initiate breast cancer stem cell renewal and may serve as a potential biomarker of breast cancer prognosis. Conclusion: CDK12 overexpression promotes breast cancer tumorigenesis and maintains the stemness of breast cancer by activating c-myc/β-catenin signaling. Inhibiting CDK12 expression may become a potential therapy for breast cancer.

2021 ◽  
Author(s):  
Samyuktha Suresh ◽  
Solène Huard ◽  
Amélie Brisson ◽  
Fariba Némati ◽  
Coralie Poulard ◽  
...  

Identifying new therapeutic strategies for triple-negative breast cancer (TNBC) patients is a priority as these patients are highly prone to relapse after chemotherapy. Here, we found that protein arginine methyltransferase 1 (PRMT1) is highly expressed in all breast cancer subtypes. Its depletion decreases cell survival by inducing DNA damage and apoptosis in various breast cancer cell lines. Transcriptomic analysis and chromatin immunoprecipitation revealed that PRMT1 regulates the epidermal growth factor receptor (EGFR) and the Wnt signaling pathways, reported to be activated in TNBC. The enzymatic activity of PRMT1 is also required to stimulate the canonical Wnt pathway. Recently developed type I PRMT inhibitors decrease breast cancer cell proliferation and show anti-tumor activity in a TNBC xenograft model. These inhibitors display synergistic interactions with some chemotherapies used to treat TNBC patients, as well as the EGFR inhibitor, erlotinib. Therefore, targeting PRMT1 in combination with drugs used in the clinic may improve current treatments for TNBC patients.


Author(s):  
Yukun Wang ◽  
Xiang Yuan ◽  
Jing Li ◽  
Zhiwei Liu ◽  
Xinyang Li ◽  
...  

HER2+/HR+ breast cancer is a special molecular type of breast cancer. Existing treatment methods are prone to resistance; “precision treatment” is necessary. Pyrotinib is a pan-her kinase inhibitor that can be used in HER2-positive tumors, while SHR6390 is a CDK4/6 inhibitor that can inhibit ER+ breast cancer cell cycle progression and cancer cell proliferation. In cancer cells, HER2 and CDK4/6 signaling pathways could be nonredundant; co-inhibition of both pathways by combination of SHR6390 and pyrotinib may have synergistic anticancer activity on HER2+/HR+ breast cancer. In this study, we determined the synergy of the two-drug combination and underlying molecular mechanisms. We showed that the combination of SHR6390 and pyrotinib synergistically inhibited the proliferation, migration, and invasion of HER2+/HR+ breast cancer cells in vitro. The combination of two drugs induced G1/S phase arrest and apoptosis in HER2+/HR+ breast cancer cell lines. The combination of two drugs prolonged the time to tumor recurrence in the xenograft model system. By second-generation RNA sequencing technology and enrichment analysis of the pyrotinib-resistant cell line, we found that FOXM1 was associated with induced resistance to HER2-targeted therapy. In HER2+/HR+ breast cancer cell lines, the combination of the two drugs could further reduce FOXM1 phosphorylation, thereby enhancing the antitumor effect to a certain extent. These findings suggest that SHR6390 combination with pyrotinib suppresses the proliferation, migration, and invasion of HER2+/HR+ breast cancers through regulation of FOXM1.


2020 ◽  
pp. jbc.RA120.016345
Author(s):  
Qiong Wu ◽  
Cheng Zhang ◽  
Keren Zhang ◽  
Qiushi Chen ◽  
Sijin Wu ◽  
...  

GalNAc-type O-glycosylation, initially catalyzed by polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts), is one of the most abundant and complex post-translational modifications of proteins. Emerging evidence has proven that aberrant ppGalNAc-Ts are involved in malignant tumor transformation. However, the exact molecular functions of ppGalNAc-Ts are still unclear. Here, the role of one isoform, ppGalNAc-T4, in breast cancer cell lines was investigated. The expression of ppGalNAc-T4 was found to be negatively associated with migration of breast cancer cells. Loss-of function studies revealed that ppGalNAc-T4 attenuated the migration and invasion of breast cancer cells by inhibiting the epithelial-mesenchymal transition (EMT) process. Correspondingly, transforming growth factor beta (TGF-β) signaling, which is the upstream pathway of EMT, was impaired by ppGalNAc-T4 expression. ppGalNAc-T4 knock-out decreased O-GalNAc modification of TGF-β type Ⅰ and Ⅱ receptor (TβR Ⅰ and Ⅱ) and led to the elevation of TGF-β receptor dimerization and activity. Importantly, a peptide from TβR Ⅱ was first identified as the naked peptide substrate of ppGalNAc-T4 with a higher affinity than ppGalNAc-T2. Further, Ser31, corresponding to the extracellular domain of TβR Ⅱ, was identified as the O-GalNAcylation site upon in vitro glycosylation by ppGalNAc-T4. The O-GalNAc-deficient S31A mutation enhanced TGF-β signaling activity and EMT in breast cancer cells. Together, these results identified a novel mechanism of ppGalNAc-T4-catalyzed TGF-β receptors O-GalNAcylation that suppresses breast cancer cell migration and invasion via the EMT process. Targeting ppGalNAc-T4 may be a potential therapeutic strategy for breast cancer treatment.


2021 ◽  
Author(s):  
Tao Xueqin ◽  
Mei Jinhong ◽  
Huang Yuping

Abstract Background: Emerging evidences have demonstrated that Ubiquitin-conjugating enzyme E2T (UBE2T) is dysregulated and play critical roles in various cancers. With the development of sequencing technology, studies have discovered that UBE2T is overexpressed in breast cancer tissues. However, the biological roles of UBE2T in breast cancer are still far to clear. In the present study, Methods: We analyzed the UBE2T expression in the Cancer Genome Atlas (TCGA) database. Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to assess the expression of UBE2T in breast cancer cell lines. Cell proliferation, invasion and epithelial-mesenchymal transition (EMT) were determined by using CCK-8, EdU, Transwell and western blot assays.Results: UBE2T was highly expressed in breast cancer cell lines. Functional analysis revealed that silence or elevation of UBE2T inhibited or promoted the proliferation, migration, invasion and EMT and Wnt/β-catenin signaling pathway related markers of MCF-7 cells. Mechanically, blocking of Wnt/β-catenin pathway by XAV939 reversed the promotion effect of UBE2T overexpression on breast cancer cells’ proliferation, migration and invasion.Conclusion: Our findings emphasized that UBE2T may act as an oncogene via activating the Wnt/β-catenin pathway, which may provide a potential therapeutic target for the treatment of breast cancer.


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