In the large intestine, the multipotent stem cells are located at the base of the crypt and differentiate into three main cell types: enterocytes, goblet cells, and enteroendocrine cells. Goblet cells’ main function is the synthesis and secretion of mucins. Genetic and epigenetic changes that provide survival advantages for stem or progenitor cells resulting in the deregulation of cellular differentiation are major causes of all carcinomas.
Our laboratory has a large collection of colorectal cancer (CRC) cell lines, well characterised in terms of gene expression and mutations. We analysed the presence of goblet cells in CRC cell lines using the genes Mucin 2 (MUC2) and Trefoil factor 3 (TFF3). The genes both at the mRNA level and at the protein level were investigated. The effects of various transcription factors were assessed by knockdown and overexpression techniques.
We found that most of the cell lines are unable to produce goblet cells and that the number of MUC2 and TFF3-positive cells among the goblet cell positive cell lines was quite variable. While in the normal colon, MUC2 and TFF3 are always co-expressed, but that is not always the case in the CRC cell lines. MUC2-negative and TFF3-positive cell lines appear to reflect a novel interesting subset. The investigation of several transcription factors on goblet cell differentiation showed that downregulation of Atonal homologue 1 (ATOH1) had a dramatic effect on goblet cell production, while knocking down of SAM pointed domain ETS transcription factor (SPDEF), Caudal type homeobox 1 (CDX1), and 2 (CDX2) had a modest effect. Individually, none of these factors are sufficient to trigger the goblet cell differentiation.
As a conclusion, the percentage of goblet cells differs substantially between cell lines. Classification of the cell lines reveals an interesting major subset that has TFF3 expression without expressing MUC2. ATOH1, SPDEF, CDX1, and CDX2 had a significant effect on goblet cell differentiation, but on their own, they are not sufficient to induce the goblet cell differentiation. Understanding the mechanisms of goblet cell differentiation is important for advances in the prevention and treatment of CRC.
The authors.
1) Islamic Development Bank; 2) Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences.
All authors have declared no conflicts of interest.