An image-based method for identification of new inhibitors of Signal Transducer Activator of Transcription 1

Background: Chemotherapy and radiation resistance are major causes of failure in cancer treatment. The response to treatment in cancer cells depends on several mechanisms and pathways such as Janus kinases-signal transducers and activators of transcription JAK/STAT pathway. STAT1 was the first described transcription factor in the STAT family. STAT1 is activated by stimulation of signaling proteins such as type II interferon (IFN- γ) and the activated STAT1 translocates from cytoplasm to nucleus. The translocation of STAT1 would result in transcription and changes in the cell activity in terms of apoptosis, proliferation and angiogenesis. Overexpression of STAT1 is suggested to be involved in the development of resistance to chemotherapy and radiation. In this study, we were interested in finding an inhibitor of the STAT1 translocation. Material and methods: The cervix carcinoma cell line, HeLa, was exposed to test compounds for 2h and were then stimulated with IFN-γ to induce the translocation of STAT1. To detect STAT1-protein and the nucleus, the cells were stained with fluorescent antibodies and Hoescht 33324, respectively, using a STAT1 activator assay. The difference in fluorescence intensity between cytoplasm and nucleus was measured using a high-content microscope, ArrayScan®. Results: β-lapachone and CRA-1 were found to be inhibitors of STAT1 translocation