MicroRNA-99a-5p suppresses breast cancer progression and cell-cycle pathway through downregulating CDC25A

Area of Science:

• Molecular Biology
• Oncology
• Biochemistry

Background:

• Breast cancer is a significant global health concern with complex molecular underpinnings.
• Dysregulation of microRNAs (miRNAs) and their target genes plays a critical role in cancer development and progression.
• Understanding the specific roles of miRNAs like miR-99a-5p in breast cancer is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the association between miR-99a-5p and CDC25A in breast cancer.
• To elucidate the regulatory mechanisms of miR-99a-5p on breast cancer progression.
• To evaluate the therapeutic potential of modulating miR-99a-5p in breast cancer.

Main Methods:

• Analysis of gene and miRNA expression using The Cancer Genome Atlas (TCGA) microarray data.
• Quantitative real-time polymerase chain reaction (qRT-PCR) to measure miR-99a-5p and CDC25A levels.
• Western blot analysis for protein expression (CDC25A, ki67, cyclin D1, p21, BAX, BCL-2, BCL-XL, MMP2, MMP9).
• Bioinformatics analysis and dual luciferase assay to confirm the targeting relationship.
• In vitro assays (cell counting kit-8, Transwell, flow cytometry) to assess cell proliferation, invasion, and apoptosis.
• In vivo studies using a nude mouse xenograft model.

Main Results:

• miR-99a-5p was significantly downregulated, while CDC25A was upregulated in breast cancer tissues and cells.
• miR-99a-5p directly targets and suppresses CDC25A expression in breast cancer cells.
• Overexpression of miR-99a-5p inhibited cell proliferation and invasion, and promoted apoptosis.
• miR-99a-5p overexpression repressed CDC25A, ki67, and Cyclin D1, while upregulating p21.
• Downregulation of miR-99a-5p and upregulation of CDC25A activated cell-cycle progression.

Conclusions:

• miR-99a-5p acts as a tumor suppressor in breast cancer by targeting CDC25A.
• Modulating miR-99a-5p expression can inhibit breast cancer cell proliferation, invasion, and affect apoptosis.
• The miR-99a-5p/CDC25A axis is a critical regulator of breast cancer cell-cycle progression and represents a potential therapeutic target.