Developmental Regulation and Induction of Cytochrome P450 2W1, an Enzyme Expressed in Colon Tumors

Abstract

Cytochrome P450 2W1 (CYP2W1) is expressed predominantly in colorectal and also in hepatic tumors, whereas the levels are insignificant in the corresponding normal human adult tissues. CYP2W1 has been proposed as an attractive target for colorectal cancer (CRC) therapy by exploiting its ability to activate duocarmycin prodrugs to cytotoxic metabolites. However, its endogenous function, regulation and developmental pattern of expression remain unexplored. Here we report the CYP2W1 developmental expression in the murine and human gastrointestinal tissues. The gene expression in the colon and small intestine commence at early stages of embryonic life and is completely silenced shortly after the birth. Immunohistochemical analysis of human fetal colon revealed that CYP2W1 expression is restricted to the crypt cells. The silencing of CYP2W1 after birth correlates with the increased methylation of CpG-rich regions in both murine and human CYP2W1 genes. Analysis of CYP2W1 expression in the colon adenocarcinoma cell line HCC2998 revealed that the gene expression can be induced by e.g. the antitumor agent imatinib, linoleic acid and its derivatives. The imatinib mediated induction of CYP2W1 suggests an adjuvant therapy to treatment with duocarmycins that thus would involve induction of tumor CYP2W1 levels followed by the CYP2W1 activated duocarmycin prodrugs. Taken together these data strongly support further exploration of CYP2W1 as a specific drug target in CRC.

The CYP2W1 enzyme: regulation, properties and activation of prodrugs

“…The extent of methylation here was found to inversely correlate with the expression levels of CYP2W1 in the tumors and cell lines. A similar regulatory mechanism was also found during the development in mouse and human colon and intestine (Choong et al, 2015). Thus, a developmental shift from hypomethylation to hypermethylation in the exon 1/intron 1 CpG island of human CYP2W1 correlated with the silencing of the gene in adult age, consistent with a similar hypermethylated state of the CYP2W1 gene in the normal colon versus hypomethylation in the colon tumor tissues.…”

“…Similar fetal expression of CYP2W1 was seen in human fetuses 18 and 19 weeks of gestation with no expression in adult colon or SI (Choong et al, 2015) (Figure 1). Using our in-house polyclonal antibodies (852 Ab), we could also detect similar CYP2W1 expression in the human embryonic intestine and colon on the protein level (Choong et al, 2015). Similar pattern of protein expression was seen in the mouse embryonic GI tissues.…”

“…Thus, a developmental shift from hypomethylation to hypermethylation in the exon 1/intron 1 CpG island of human CYP2W1 correlated with the silencing of the gene in adult age, consistent with a similar hypermethylated state of the CYP2W1 gene in the normal colon versus hypomethylation in the colon tumor tissues. The epigenetic regulation in the murine Cyp2w1 gene is apparently more complex as correlation between the expression and methylation was found only in four out of six scanned CpG sites outside the canonical CpG islands (Choong et al, 2015).…”

“…A diverse set of biologically active compounds, such as 5-Aza-2 0 -deoxycytidine (AzaC), the tyrosine kinase inhibitor imatinib, linoleic acid and its two conjugates significantly increased the CYP2W1 mRNA levels in the HCC2998 human colon cancer cells constitutively expressing CYP2W1 (Choong et al, 2015). However, ligands of PPARc, CAR PXR or AhR that efficiently regulate many CYPs did not induce CYP2W1.…”

Human Cytochrome P450 2W1 Is Not Expressed in Adrenal Cortex and Is Only Rarely Expressed in Adrenocortical Carcinomas

“…In contrast, specific expression of CYP2W1 in the small intestine and colon is seen in fetal mice and in human fetuses (Choong et al 2015 [3]). Expression begins at an early stage in the embryo and is silenced shortly after birth by increased methylation of CpG-rich regions in the murine and human CYP2W1 genes [3].…”