Identification of circulating miRNAs associated to Kaiso and triple negative breast cancer in mice model

Paula Lucía Farré¹, Guillermo Nicolás Dalton¹, Rocío Belén Duca¹, Cintia Massillo¹, Kevin Gardner², Adriana De Siervi¹

Breast cancer (BCa) is the leading cause of death by cancer in women worldwide. Novel biomarkers for diagnosis and prognosis are necessary to increase patients’ survival. Previous studies showed that Kaiso (ZBTB33) was increased in several cancer tissues, including BCa. This transcription factor regulates different genes/pathways that increase BCa growth and metastasis. Nuclear Kaiso predicted poor survival in women of African heritage who had triple negative BCa (TNBC). Due that Kaiso binds to LC3 it was linked to the secretory autophagy pathway. The aim of this work was to investigate the role of Kaiso on TNBC xenograft secretion of circulating miRNAs outside the tumor. We inoculated NOD scid gamma (NSG) female mice with Kaiso depleted (shKaiso) MDA-MB-231 (TNBC) or control cell lines. After tumor growth, we sacrificed the mice to collect blood and tumor samples. shKaiso inoculated mice showed alteration of the levels of MDA-MB-231-derived circulating miRNAs related to BCa and Kaiso, including miR-125b-5p, -16-5p, -21-5p, 93-5p. We also found that several Kaiso target genes were modulated in BCa xenografts, such as CCND1, FOXA1, DNMT1 and GATA3. Moreover, the autophagy-related proteins LC3A/B showed a significant accumulation in cytoplasmatic sites of shKaiso inoculated mice in primary tumors and metastatic sites. These findings suggest that Kaiso might be involved in cellular secretion of miRNAs, which reinforce the role of Kaiso in autophagy.