There was an error published in Development 133, 4269-4279.The Acknowledgements should have read 'Sponsored by grants CA42715, CA93840 and P20RR017695'. The authors apologise to readers for this mistake.

No abstract

Carcinoembryonic antigen (CEA)-related cell adhesion molecule 1 (CEACAM1) is a member of the CEA family of immunoglobulin-like adhesion molecules with two major splice variants, CEACAM1 a -4L and CEACAM1 b -4S, differing in the length of their COOH-terminal cytoplasmic tail. Both forms are down-regulated in prostate and liver carcinomas relative to normal tissues. We have previously shown in a nude mouse xenograft model that restoration of CEACAM1 a -4L expression in human prostate carcinoma cells (PC-3) suppresses tumorigenicity, an effect observed with carcinomas from several other tissues but never established for hepatocellular carcinomas. In this report, we have examined the effect of CEACAM1 a -4L on tumorigenicity of 1682A, a rat hepatocellular carcinoma that grows on the omentum when injected into the peritoneal cavity. Results show that restoration of CEACAM1 a -4L expression at levels 13-and 0.45-fold compared with negative controls or normal hepatocytes, respectively, completely suppressed the formation of 1682A tumor nodules on the omentum at 3 weeks after injection. In contrast, 1682A cells infected with CEACAM1 b -4S or an empty retroviral vector formed multiple clusters of tumor nodules. Although tumor nodules of 1682A cells positive and negative for CEACAM1 a -4L did not display significant differences in histologic organization, aggregates formed in vitro by 1682A-L were smaller in size and displayed enlarged intercellular spaces relative to their 1682A-V counterparts. Restoration of CEACAM1 a -4L expression did not elevate levels of apoptosis but seemed to cause an increase in the length of G 1 . This is the first demonstration of CEACAM1 a -4L-induced tumor suppression in liver carcinomas using a quantifiable i.p. syngeneic transplantation model.

Recently published protocols using Reverse Transcriptase Polymerase Chain reaction (RT‐PCR) for prostate specific antigen (PSA) provide a sensitive means for detecting circulating prostate cancer cells. Attempts to use these assays for staging of prostate cancer have produced conflicting results. As a first step towards rectifying these discrepancies, a modified immunobead‐RT‐PCR assay capable of detecting as few as 10 prostate cancer cells in 8cc of blood was developed. This 10 fold increase in sensitivity was achieved in part by introducing two target cell enrichment steps. As a model system to assess sensitivity of the modified assay, template RNA was extracted from PSA positive human carcinoma cells suspended in human blood and isolated with immunomagnetic beads following incubation with an epithelium specific antibody. After 45 cycles of PCR, product from as few as 10 target cells could be readily detected when displayed on a 2% agarose gel stained with SYBR Green fluorescent dye. The identity of amplified DNA fragments was confirmed by Southern blot hybridization. When applied to blood samples from patients with proven metastatic disease, the immuno‐bead RT‐PCR assay was successful in detecting circulating PSA positive epithelial cells, suggesting this assay may be useful for assessment of disease progression or recurrence. J. Clin. Lab. Anal. 11:346–350, 1997. © 1997 Wiley‐Liss, Inc.

S U M M A R YIn the present report, we have compared the phenotype and growth of small hepatocyte progenitors (SHPs) induced by retrorsine/partial hepatectomy (R/PH) and small hepatocytes (SHs) isolated from normal adult liver. SHs were isolated by a combination of differential centrifugation and Percoll isodensity fractionation from a liver cell suspension prepared by collagenase perfusion of a dipeptidyl peptidase IV (DPPIV)-positive Fischer F344 rat liver. Following further purification by flow cytometry, the SH-R3 fraction was transplanted via the portal vein into R/PH-treated, DPPIV-negative Fischer F344 rats. Frozen sections from tissue harvested at 5, 7, and 21 days after transplantation were analyzed by indirect immunofluorescence to compare the phenotypic characteristics of colonies formed by exogenous SH-R3s and endogenous SHPs. Colonies of transplanted SHs and endogenous SHPs displayed similar histologies and phenotypes but were distinguished from surrounding hepatocytes by their elevated expression of transferrin receptor. SH-R3 colonies were frequently located within clusters of g-glutamyl transpeptidase-positive host hepatocytes. Although significantly smaller at 5 and 7 days after PH, by day 21, SH-R3 colonies were similar in size to those formed by SHPs. The present results suggest that endogenous SHPs are derived, at least in part, from SHPs. (J Histochem Cytochem 58:61-72, 2010)

This novel model represents a simple and robust system of xenogeneic hepatocyte transplantation that could be applied to studies of liver biology, regeneration and hepatocyte transplantation.