Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR) is a method of choice for quantifying micro RNAs (miRNAs). Typically, RT-qPCR data are normalized to reference genes. While miRNAs are used for diagnosing and subtyping breast cancer, various studies show their deregulation in this condition, thus, undermining miRNAs' utility as a reference. This review examines the expression pattern of miR-16 and suggests normalization approaches for breast cancer. We analyzed the data from selected peer-reviewed studies to calculate the standardized mean difference (SMD) with subsequent Chi-square testing and identified the difference in miR-16 expression between breast cancer patients and healthy controls. With a negative SMD value of-0.56 and Chi-square of 62.62 (p-value = 0.05), the deregulation of miR-16 in breast cancer was confirmed. High variance in the stability value (SV) of miR-16 expression levels confirmed its inappropriateness as a control gene in breast cancer. The combination of miR-16 and miR-425 was confirmed as an accurate endogenous control.
Keywords: breast cancer; combined control genes; internal control; miR-16.