Caco-2 Colorectal Cancer Cells Research Articles

Gene expression profiles of ABC transporters and cytochrome P450 3A in Caco-2 and human colorectal cancer cell lines.

The mRNA levels of MDR1 (P-glycoprotein), multidrug resistance-associated proteins (MRP1, MRP2), cytochrome P450 3A (CYP3A) and villin in human colorectal cell lines (HCT-15, LoVo DLD-1, HCT-116 and SW620) were quantitatively compared with those in Caco-2 cells. The mRNA levels were determined by real time quantitative polymerase chain reaction and expressed as the relative concen trations of MDR1 mRNA to glyceraldehyde-3-phosphate dehydro genase (GAPDH) mRNA. RESULTSl MDR1 mRNA was expressed in HCT-15 LoVo and DLD-1 cells at similar or lower level to Caco-2. The expression of MRP mRNA in the cell lines tested was comparable with Caco-2. MRP. mRNA was detected only in HCT-116 and SW620 at significantly lower level than Caco-2. CYP3A mRNA was detected in HCT-15 LoVo, DLD-1 and SW620 at similar level to Caco-2. HCT-15 LoVo and DLD-1 cells express proteins important for regulating the intestinal absorption of drugs, i.e., MDR1 MRP1 and CYP3A, whereas HCT-116 and SW620 cells were not acceptable for evaluation of absorption properties of drug candidates

Tumor suppressor and anti-inflammatory actions of PPARgamma agonists are mediated via upregulation of PTEN.

The PTEN tumor suppressor gene modulates several cellular functions, including cell migration, survival, and proliferation [1] by antagonizing phosphatidylinositol 3-kinase (PI 3-kinase)-mediated signaling cascades. Mechanisms by which the expression of PTEN is regulated are, however, unclear. The ligand-activated nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) [2] has been shown to regulate differentiation and/or cell growth in a number of cell types [3, 4, 5], which has led to the suggestion that PPARgamma, like PTEN [1, 6], could act as a tumor suppressor. PPARgamma has also been implicated in anti-inflammatory responses [7, 8], although downstream mediators of these effects are not well defined. Here, we show that the activation of PPARgamma by its selective ligand, rosiglitazone, upregulates PTEN expression in human macrophages, Caco2 colorectal cancer cells, and MCF7 breast cancer cells. This upregulation correlated with decreased PI 3-kinase activity as measured by reduced phosphorylation of protein kinase B. One consequence of this was that rosiglitazone treatment reduced the proliferation rate of Caco2 and MCF7 cells. Antisense-mediated disruption of PPARgamma expression prevented the upregulation of PTEN that normally accompanies monocyte differentiation and reduced the proportion of macrophages undergoing apoptosis, while electrophoretic mobility shift assays showed that PPARgamma is able to bind two response elements in the genomic sequence upstream of PTEN. Our results demonstrate a role for PPARgamma in regulating PI 3-kinase signaling by modulating PTEN expression in inflammatory and tumor-derived cells.