DOWN‐REGULATION OF STAT3 BY AZT TREATMENT

Abstract

STAT (Signal Transducer and activators of transcription) is a family that has the ability to be a transcription factor in the nucleolus and a signal transducer in the cytoplasm. This family has unique structural domains where a tyrosine becomes phosphorylated cytosine-stimulated cells, like the Janus kinases. This family regulates numerous genes in different developmental stages of the organism. If STAT members are missing or wrongly expressed, it could cause numerous diseases and syndromes. Is composed of 7 members STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B and STAT6, which mediate the response to cytokines and growth factors. The purpose of our study is to determine in vitro expression pattern for the gene STAT3 using CEMss cells cultures treated with AZT (Azidothymidine) antiviral drug. Initially, we optimized conditions and perform standard curve validation with greater efficiencies to 98% and R2 of 0.946 for S15 housekeeping gene as internal reference and STAT3 gene. The melting curve for relative expression of S15 resulted with a Tm 86.9°C and STAT3 with 79.6°C. Finally, analysis for STAT3 was performed the Relative Quantification and Comparative Ct (ΔΔCt) real-time RT-PCR at the conditions previously optimized. As a result, after treatment with AZT the STAT3 gene remained down-regulated from 1 day (fold change -0.6) to 10 days trial (fold change -1.3). This suggests that down-regulation of STAT3 gene expression by AZT and this gene should be evaluated as a potential biomarker such as it is involved in resistance to anticancer drugs.