Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Biochemistry

Breast cancer is one of the most common cancers in women worldwide. Over 1.5 million women (25% of all women with cancer) are diagnosed with breast cancer every year throughout the world. Purpose & Methodology Quantitative assessment of plasma miRNA-34a & miRNA-125b expression was performed by qRT-PCR to predict outcome from neoadjuvant chemotherapy. Thirty nine newly diagnosed locally advanced breast cancer female patients with 10 age and sex matched healthy volunteers were included in the study. Results We performed ROC curve analysis to evaluate the diagnostic value for the miRNA-34a with AUCs = 0.995, cutoff point of 2.57 sensitivity 97.4%, specificity 100%, PPV 100%, NPV 83.3% and accuracy 97.7%.miRNA-125b had AUC = 0.68 and a cutoff point of 8.69 with sensitivity 66.7%, specificity 70.0%, PPV 90.6%, NPV 41.2% and accuracy 73.5%. miRNA-34a expression were significantly higher in breast cancer patients compared to controls with p value <0.001*. Also, miRNA-34a expression level was significantly higher in patients with progressive disease with P value =0.03*. However, miRNA-125b expression levels were insignificantly higher in responsive patients with p value = 0.2. Conclusion miRNAs are crucial candidates for novel molecular targeted therapies due to their capability to regulate numerous genes in molecular pathways. miRNA-34a can predict chemotherapeutic resistance associated with higher expression levels in non-responsive patients

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