Evaluation of the clinical utility of kallikrein-related peptidase 6 gene (KLK6) downregulation in breast cancer.

Abstract

10606 Background: Breast cancer (BC), the most common malignancy among the female population, remains a crucial public health problem. The identification and exploitation of novel molecular biomarkers can contribute in the multidimensional approach which is required for optimal management of BC patients. The abnormal expression of several KLK members has been documented for breast cancer. Interestingly, many of these genes are found to be potential prognostic markers for this malignancy. KLK6 expression is positively associated with tumor progression in various human malignancies; however in breast cancer, it can restrain tumor progression. We therefore sought to investigate the possible clinical value of KLK6 as a breast cancer biomarker. Methods: Total RNA was isolated from 107 breast tumors and their matched normal compartments. After testing the quality of the extracted RNA, cDNA was prepared by reverse transcription. Quantitative Real-time PCR was performed, for KLK6 mRNA quantification, using the SYBR Green chemistry. Relative quantification analysis was made using the comparative Ct (2-ΔΔCT) method. HPRT1 was used as an endogenous control gene and BT-474 breast cancer cell line served as a calibrator. Results: KLK6 mRNA levels were significantly downregulated in the cancerous breast tissue specimens compared to their normal counterparts (p<0.001). Additionally, a negative association was observed between KLK6 expression status and tumor stage, given the fact that 54.2% of less advanced breast tumors (TNM stage≤ T2a) were KLK6-positive compared to the 34.6% of more advanced-stage tumors (TNM >T2a) (p=0.034). Moreover, a statistically significant negative correlation was documented between KLK6 mRNA levels and estrogen (p<0.001) and progesterone receptor (p=0.003) statuses. Conclusions: The downregulation of KLK6 in cancerous compared to normal sections of breast tissue samples reflects the reported tumor suppressor properties of KLK6 gene in breast malignancies. Furthermore, the negative association of KLK6 mRNA expression with tumor stage, ER and PR statuses reveals the putative role of KLK6 as a promising prognostic breast cancer biomarker.