Let-7d and miR-185 Impede Epithelial-Mesenchymal Transition by Downregulating Rab25 in Breast Cancer

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• MicroRNA (miRNA) expression is frequently deregulated in various cancers, including breast cancer (BC).
• Specific miRNAs, such as let-7d and miR-185, have been implicated in cancer development, but their precise roles and mechanisms in BC require further elucidation.
• The protein Rab25 and its association with cancer progression, particularly epithelial-mesenchymal transition (EMT), are of significant interest.

Purpose of the Study:

• To investigate the expression patterns and functional roles of let-7d and miR-185 in breast cancer.
• To explore the potential correlation between let-7d, miR-185, and Rab25 in BC.
• To elucidate the underlying molecular mechanisms, including the involvement of the EMT pathway.

Main Methods:

• Quantitative real-time PCR (qRT-PCR) was employed to assess the expression levels of let-7d, miR-185, Rab25, and snail in tumor tissues and adjacent normal tissues from 110 BC patients.
• Immunohistochemistry (IHC) and western blot analyses were performed to evaluate Rab25 and Snail protein expression in BC samples.
• Bioinformatics database analyses were utilized to predict potential miRNA-target interactions.

Main Results:

• let-7d and miR-185 expression levels were significantly downregulated in breast cancer tissues compared to adjacent normal tissues (P < 0.05).
• Downregulation of let-7d and miR-185 was correlated with tumor size, stage, and lymph node metastasis.
• Rab25 was identified as a direct target of both miR-185 and let-7d, with its expression inversely correlated to these miRNAs. Upregulation of Rab25 was found to enhance Snail expression, a key mediator of EMT.

Conclusions:

• let-7d and miR-185 function as tumor suppressors in breast cancer by inhibiting EMT through the targeting of Rab25.
• The let-7d/miR-185/Rab25 axis represents a novel regulatory pathway in BC progression.
• Targeting the let-7d and miR-185/Rab25 interaction holds promise as a potential therapeutic strategy for breast cancer treatment.