molecular-profiling-invasive-tumor-microenvironment-3-dimensional

Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and <em>Ex vivo</em> Fibroblasts

Invading colorectal cancer (CRC) cells have acquired the capacity to break free from their sister cells, infiltrate the stroma, and remodel the ...

University of Southampton School of Medicine

MicroRNAs (miRNAs) are a class of small highly conserved RNAs that provide widespread expressional control through the translational repression of mRNA. MiRNAs have fundamental roles in the regulation of intracellular processes, and their importance during malignant transformation and metastasis is becoming increasingly well recognized. An important event in the metastatic cascade is epithelial to mesenchymal transition (EMT), a reversible phenotypic switch over, which endows malignant epithelial cells with the capacity to break free from one another and invade the surrounding stroma. Our understanding of EMT has been significantly improved by the characterization of miRNAs that influence the signalling pathways and downstream events that define EMT on a molecular level. Here, we detail the role of miRNAs in EMT, and in doing so demonstrate their importance in the early stages of the metastatic cascade; we discuss a significant body of data that suggest new opportunities for drug development, and we highlight critical knowledge gaps that remain to be addressed.

MicroRNAs: critical regulators of epithelial to mesenchymal (EMT) and mesenchymal to epithelial transition (MET) in cancer progression.

Although microRNAs (miRNA) have been broadly studied in cancer, comparatively less is understood about their role in progression. Here we report that miR-153 has a dual role during progression of colorectal cancer by enhancing cellular invasiveness and platinum-based chemotherapy resistance. miRNA profiling revealed that miR-153 was highly expressed in a cellular model of advanced stage colorectal cancer. Its upregulation was also noted in primary human colorectal cancer compared with normal colonic epithelium and in more advanced colorectal cancer stages compared with early stage disease. In colorectal cancer patients followed for 50 months, 21 of 30 patients with high levels of miR-153 had disease progression compared with others in this group with low levels of miR-153. Functional studies revealed that miR-153 upregulation increased colorectal cancer invasiveness and resistance to oxaliplatin and cisplatin both in vitro and in vivo. Mechanistic investigations indicated that miR-153 promoted invasiveness indirectly by inducing matrix metalloprotease enzyme 9 production, whereas drug resistance was mediated directly by inhibiting the Forkhead transcription factor Forkhead box O3a (FOXO3a). In support of the latter finding, we found that levels of miR-153 and FOXO3a were inversely correlated in matched human colorectal cancer specimens. Our findings establish key roles for miR-153 overexpression in colorectal cancer progression, rationalizing therapeutic strategies to target expression of this miRNA for colorectal cancer treatment.

Article	Year
MicroRNAs: critical regulators of epithelial to mesenchymal (EMT) and mesenchymal to epithelial transition (MET) in cancer progression. Biology of the cell / under the auspices of the European Cell Biology Organization\| PubMed ID: 22188537	2012
miR-153 supports colorectal cancer progression via pleiotropic effects that enhance invasion and chemotherapeutic resistance. Cancer research\| PubMed ID: 23950211	2013

Marc D. Bullock

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