Characterization of the DiFi Rectal carcinoma cell line derived from a familial adenomatous polyposis patient

Abstract

The DiFi human colorectal cancer cell line was recently established from a familial adenomatous polyposis patient with extracolonic features characteristic of the Gardner syndrome. These cells have now been propagated for 150 passages in standard culture media and vessels without feeder layers or collagen coatings. They retain features of colonic epithelial cells such as surface microvilli, secretory vesicles, and desmosomes. Cytosol of DiFi cells contains a high level (502 U/mg protein) of the mucin CA 19-9. In addition, DiFi cells produce carcinoembryonic antigen, and induce tumors in athymic mice. Cytoskeleton analysis of DiFi cells by fluorescence microscopy showed a pronounced disorganization of actin cable structure. The isozyme genetic signature of DiFi cells is unique (0.01 probability of finding the same genetic signature in a different cell line), differs from that of HeLa cells, and has expressional features seen in other colorectal cell lines. The DiFi cell karyotype is tetraploid, contains many marker chromosomes, and shows numerous episomal particles. Two copies of chromosome 18 were absent, and only a single normal chromosome 17 was found. This parallels detection of allelic losses from DiFi cell DNA at loci on chromosomes 17p and 18 using molecular (cDNA) probes. DiFi cells clearly express transcripts for the c-myc proto-oncogene, the c-myb proto-oncogene, and the p53 tumor suppressor gene. Transforming growth factor beta inhibits DiFi cell growth in soft agar and suppresses c-myc expression in these cells. The value of this cell line in the study of genetic alterations in colorectal cancer is discussed.

Digital karyotyping

“…These observations were consistent with CGH analyses (see below) and the previously reported karyotype of DiFi cells (20).…”

“…Analysis of the DiFi data revealed a much wider variation in tag density, ranging from 0.089 to 0.27 for autosomal chromosomes. In agreement with the origin of these tumor cells from a female patient (20), the tag density of the Y chromosome was 0.00. Estimates of chromosome number *Copy number alteration refers to the gain or loss of chromosomal regions in the context of the normal diploid genome, where the normal copy number is 2.…”

Induction of cyclo-oxygenase-2 mRNA by prostaglandin E2 in human prostatic carcinoma cells

“…However, as in PC-3 cells, exogenous dmPGE2 also increased the COX-2 mRNA levels time-dependently, with the highest accumulation seen 2 h after dmPGE2 addition. We also examined the COX-2 expression in human colonic carcinoma cells [derived from a familial adenomatous polyposis (Gardner's syndrome) patient], DiFi cells (Olive et al, 1993) and human breast carcinoma (MDA-MB-134) cells (Cailleau et al, 1974). As shown in Figure SB, up-regulation COX-2 mRN accumulation in response to dmPGE2 administration was also observed in these two cell lines.…”

TGFα and Amphiregulin Paracrine Network Promotes Resistance to EGFR Blockade in Colorectal Cancer Cells

“…The cell line-specific responsiveness to EGFR ligands is intriguing and may reflect differences in EGFR signaling dependency. For example, DiFi are extremely sensitive to cetuximab-mediated EGFR blockade likely due to EGFR gene amplification that results in protein overexpression (17)(18)(19).…”