Effect of soluble Carcinoembryonic antigen on myogenic and enterocytic differentiation

Carcinoembryonic antigen (CEA), a glycophosphatidyl inositol (GPI) anchored glycoprotein, is over-expressed in various cancers, including colorectal carcinomas. Inhibition of cell differentiation can cause cancer. Previous studies show transfection and over-expression of CEA gene in myoblasts or colonocytes leads to inhibition of cell differentiation. We investigated whether soluble CEA has a role in inhibition of cell differentiation.

Monolayer cultures of L6, C2C12, Caco-2 and CHO cell lines were grown in dulbecco's modification of eagle's medium (DMEM) containing 10% fetal bovine serum (FBS). For differentiation induction C2C12 and L6 cell lines media, was changed to DMEM containing 2% horse serum. CEA concentration was measured in harvested media by ELISA assay. H&E staining, CK assay and RT-PCR for myogenin gene were used for C2C12 differentiation experiments.

The results showed although commercial pure CEA and LS-180 conditioned media (contain high level of CEA) have inhibitory effects on Caco-2 differentiation, but it can also inhibit differentiation of control groups. We observed the effect of high concentration of CEA (5μg/ml) on L6 differentiation is identical with the effect of BSA as control. C2C12 differentiation was inhibited in response to LS-180 conditioned media at morphological level and myogenin expression. CK activity was significantly lower in LS-180 conditioned media (P= 0.0012) and CHO (P= 0.0002) conditioned media groups in comparison to control group.

Our finding shows soluble CEA antigen did not have a significant effect on cell differentiation.