Background: Growing evidence has revealed the critical regulatory role for circular RNAs (circRNAs) in cancer. This study aimed to explore the function of circ_0001387 in breast cancer (BC). Methods: Circ_0001387, miR-136-5p, and spindle and kinetochore-associated protein 2 (SKA2) levels were analyzed by quantitative real-time polymerase chain reaction. Clone formation and 5-ethynyl-2 0 -deoxyuridine assays were used to analyze cell proliferation. Cell apoptosis and cell migration and invasion abilities were analyzed using flow cytometry or transwell assay. Mechanism assay was used to confirm the association between miR-136-5p and circ_0001387 or SKA2. The effect of circ_0001387 on tumor growth in vivo was analyzed by the xenograft mice model. Results: Circ_0001387 and SKA2 were expressed at high levels, whereas miR-136-5p was lowly expressed in BC tissues and cells. Meanwhile, the downregulation of circ_0001387 restrained BC cell progression in vitro and in vivo. Circ_0001387 competitively bound to miR-136-5p to regulate BC cell malignant behaviors. SKA2 was targeted by miR-136-5p, and SKA2 reinstated the suppressive effect of miR-136-5p upregulation in BC cells. Conclusion: Our study indicated that circ_0001387 contributed to BC cell progression through miR-136-5p/SKA2 axis.
Background: Postpartum breast cancer (PPBC) as an independent entity different from PABC. PPBC is defined as breast cancer (BC) diagnosed within 5 years after delivery in many relevant literatures and is associated with a poor prognosis and a decrease in overall survival. PPBC patients commonly present with inflammatory breast cancer (IBC) phenotype, multifocal lesions, and lymph node metastasis. Hormone receptor-positive (HR+) PPBC is an under-investigated subtype. In PPBC, the risk of death of HR+ subtype significantly increased two-fold, while that was only modestly increased for triple-negative breast cancer (TNBC) subtype, and was not significant in human epidermal growth factor receptor 2-positive (HER2+) subtype. HR+ PPBC is a subtype associating with enhanced signatures of cell cycle control, T-cell activation and exhaustion, decreased HR signaling, and altered P53 signaling. The recommended treatment for HR+ PPBC patients is still lacking. Cyclin-dependent kinase (CDK) 4/6 inhibitors are used as a novel treatment standard not only in pretreated patients but also in the first-line setting of HR+ metastatic breast cancer (MBC). However, there is no clinical case report on the application and efficacy of CDK4/6 inhibitors in HR+ PPBC patients.Case Description: This article describes the clinical cases of two patients with advanced HR+ PPBC who were rapidly relieved after receiving leuprorelin combined with letrozole combined with dalpiciclib. We reviewed the related literature of PPBC, and found that HR+ PPBC has not been clinically classified as a BC subtype, and only some basic studies suggested that HR+ PPBC may be sensitive to CDK4/6 inhibitors.The purpose of this study is to provide the basis for the related research on the therapeutic effect of CDK4/6 inhibitors in HR+ PPBC through the report of clinical cases.Conclusions: This article reports for the first time the good therapeutic effects of CDK4/6 inhibitors on HR+ PPBC patients. Based on our findings, we suggest that dalpiciclib combined with endocrine therapy can be considered as the first-line treatment for patients with advanced HR+ PPBC. Our case report provides new clinical evidence for the related research on the role of CDK4/6 inhibitors in HR+ PPBC therapy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.