Investigating The Microrna-Mediated Target Regulations Associated with Metastasis of Cancer:Special Focus on Soft Tissue Sarcoma and Breast Carcinoma

Abstract

Cancer metastasis, a hallmark of the multifaceted disease is of extreme clinical relevance as it is responsible for death in 90% of individuals suffering from it. Despite the advancement in understanding the metastatic processes, the molecular mechanism and critical regulators involved in this complex multi-stage process still remains elusive. MicroRNAs (miRNA), which are crucial regulators in a wide array of biological processes, are also implicated in cancer metastasis. In this study, we deciphered the miRNA mediated regulations of cancer metastasis in two different cancer types, soft tissue sarcoma (STS) and breast carcinoma. Metastasis in STS is poorly understood compared to cancers of epithelial tissue origin, carcinomas. We harnessed the potential of expression profiles of genes and miRNAs of different high-grade STS in identifying the crucial regulators of metastasis. We amalgamated gene and miRNA expression profiles with curated data on various regulatory interactions to predict transcription factor (TF)-miRNA-target gene regulatory networks and paths in STS metastasis. It unveiled some novel TFs, miRNAs, and their targets, which are conjectured to play a critical role in metastasis of STS. Our Notch signaling sub-network analysis uncovered
miR-21 and miR-34a as novel regulators of Notch signaling in STS metastasis which also regulated other hub TFs in the networks. Further, acyclic path analysis from STS metastasis specific sub-network deploying the tool ‘RiNAcyc’ developed by us identified a 15 node active path. This potential path highlights the crucial role of MYC-mediated miRNA regulation which was further verified by co-expression analysis in sarcoma. The path also revealed the importance of miR-215 targeting TYMS, a potential chemotherapeutic target in different cancers, which is usually upregulated. The co-expression analysis corroborated with qRT-PCR expression analysis tempted us to conjecture that miR-215 and TYMS could be potential candidate for prognostic indicator of chemotherapeutic benefits in STS metastasis. We also identified anti-metastatic miR-429 targeting pro-metastatic KIAA01010 gene to play a role in STS metastasis. We observed miR-429 to inhibit proliferation, migration, and anchorage independent growth via targeting KIAA0101 in metastatic fibrosarcoma cell line. KIAA0101 overexpression was also seen to be associated with lower survival among sarcoma patients. Further, taking advantage of experimental models, we studied metastasis in 4T1 mouse model of breast cancer metastasis and found miR-31 to have a pro-metastatic role in breast cancer. Additionally, we performed Ago2-IP for in-vitro target identification in parallel
with polysome profiling to understand how miR-31 mediated its target gene regulation during breast cancer metastasis. We evaluated levels of mRNA and translation profiles of selected miR-31 targets that have a role in metastasis. We found Myh9 to be regulated both at transcriptional level and translational level, and Acsl4 only at translational level in metastasis of breast cancer. The present study catapulted the understanding of miRNA mediated target regulations in cancer metastasis in STS and breast cancer, which might aid in identifying potential miRNAs for targeted therapies in metastasis.