Gene Expression in T Regulatory Cells and the Molecular Pathways Involved in Colorectal Cancer Development.
By : Nor Adzimah Johdi (adzimah@ppukm.ukm.edu.my)
Regulatory T cells (Treg), a subset of CD4+ T cells, play a pivotal role in regulating the immune homeostasis. An increase in Treg numbers was reported in many cancers leading to immune suppression and evasion in cancer patients. However, little is known about the molecular mechanism of their development and the pathways involved in maintaining tolerance and immune homeostasis. In this study, we compared the Treg gene expression profiles and pathways from healthy volunteers (N, n=15), colorectal polyps (P, n=15) and colorectal cancer (CRC, n=15) patients. The Treg was analyzed and sorted via FACS using the CD4+CD25+CD127lowFoxP3+ markers. A fraction from the sorted Treg was used for microarray analysis and another fraction for in vitro expansion and functional assays. Cytokine level from the cultured supernatant were measured using beads array. Our results showed that the Treg number and percentage were increased significantly in ascending manner from normal, polyps to CRC patients. Functional assays showed that the Treg can suppress the autologous PBMC up to 12.4 %. TGF-β and IL-10 were significantly increased in the culture supernatant that was treated with Treg. Thirty-eight genes were differentially expressed in both CRC and P, 22 genes were differentially expressed only in CRC while 31 only in P. Most of these genes were involved in cell cycle, cytokine and chemokines receptors/ligand and T cell pathways. These findings suggest that there are mechanisms that influence the accumulation and retention of Treg at tumour sites and thus their function in suppressing the immune response of T effector cells, hinting the importance of Treg as a target for immunotherapy.
7 days after stimulation (4x)
14 days after stimulation (20X)