Role of Let-7 Family miRNAs in Migration of Colorectal Cancer HCT 116 and Caco-2 Cells After Stimulation by the Adipokine Vaspin. Time-Lapse Live-Cell Microscopic Observations

Changes of transcript levels are among the first observable cellular responses to internal or external stimuli. Those changes may be caused by the well known phenomena of RNA interference, especially by directly acting, transcript-specific micro RNAs (miRNAs), capable of influencing gene expression by activation or silencing at the level of DNA or mRNA. It may therefore be crucial to estimate the expression levels of both a mRNA and of the miRNAs influencing it. Micro RNA level changes may also be relevant in changes of the influence of signalling pathways on specific genes. One of the greatest threats to developed societies nowadays is obesity, which is connected to various health problems including colon or breast cancer [9, 34]. In many studies a connection between adipose tissue-derived hormonal activation and obesity can be observed. Adipokines are various regulators (growth factors, cytokines) of different signalling pathways, and could play a significant role in stimulation cell proliferation, cell cycle, angiogenesis, and also tumour growth and metastasis [21]. The let-7 miRNA family seems to be a good candidate to study adipose tissue-derived hormonal activation especially cancer migration and metastasis in cancer cells due to its involvement in conservative pathways with various nuclear factors like factor-B, Lin28/Let7 and TNF-alpha [15]. In this paper we have studied the regulatory role of miRNA let-7 in migration of HCT 116 colorectal cancer cells, and additionally in Caco-2 cells after hormonal stimulation with the adipokine vaspin. We found stimulatory effects of vaspin on Caco-2 cells at a dose of 3 ng/ml after 72 h of observations by time lapse live-cell microscopy in Wound Healing assays.