Loss of E2F4 activity leads to abnormal development of multiple cellular lineages

We have generated mice deficient in E2F4 activity, the major form of E2F in many cell types. Analysis of newborn pups deficient in E2F4 revealed abnormalities in hematopoietic lineage development as well as defects in the development of the gut epithelium. Specifically, we observed a deficiency of various mature hematopoietic cell types together with an increased number of immature cells in several lineages. This was associated with an increased frequency of apoptotic cells. We also found a substantial reduction in the thickness of the gut epithelium that normally gives rise to crypts as well as a reduction in the density of villi. These observations suggest a critical role for E2F4 activity in controlling the maturation of cells in a number of tissues.

Human leukocyte antigen class I allelic and haplotype loss in squamous cell carcinoma of the head and neck: clinical and immunogenetic consequences

The expression of human leukocyte antigen (HLA) class I molecules on the cell surface is necessary for the presentation of peptide antigens to cytotoxic CD8+ T lymphocytes of the immune system. Down-regulation of HLA class I gene expression has been implicated in tumorigenesis, including squamous cell carcinoma of the head and neck (SCCHN). Loss of MHC class I antigens may be one mechanism by which tumor cells escape immune detection. We performed prospective immunostaining of 26 primary SCCHN tumors and samples of normal mucosa harvested several centimeters away from the primary tumor, using a large panel of antibodies directed against allele-specific as well as monomorphic determinants of HLA class I molecules. Loss of expression of HLA class I proteins in the tumor was found in 50% (13 of 26) of primary tumors and was highly correlated with HLA loss in the corresponding normal mucosa (P < 0.0001). Further analysis demonstrated that the loss of HLA class I expression in the tumor was significantly associated with regional lymph node metastases (nodal stage; P = 0.0388), and that the number of HLA class I alleles lost in the normal mucosa was associated with subsequent development of a new primary aerodigestive tract cancer (P = 0.042). A patient with two metachronous cancers available for analysis had no evidence of HLA loss in the first tumor, demonstrated allelic loss in the second cancer, and subsequently died of disease. These results suggest that the loss of expression of HLA class I alleles may have prognostic implications.

Constitutive activation of Stat3 signaling abrogates apoptosis in squamous cell carcinogenesis in vivo

Field cancerization predisposes the upper aerodigestive tract mucosa to the formation of multiple primary tumors, when exposed to environmental carcinogens. Up-regulation of epidermal growth factor receptor occurs early in squamous cell carcinogenesis and is critical for the loss of growth control in a variety of human cancers, including head and neck squamous cell carcinomas. In these tumor cells in culture, epidermal growth factor receptor stimulation initiates signaling via persistent activation of selective STAT proteins. To determine the timing of Stat3 activation in head and neck carcinogenesis, we studied the expression and constitutive activation of Stat3 in tumors and normal mucosa from patients with head and neck cancer compared with mucosa from controls without cancer. Stat3 was up-regulated and constitutively activated in both primary human head and neck tumors as well as in normal mucosa from these cancer patients compared with control normal mucosa from patients without cancer. In vivo liposome-mediated gene therapy with a Stat3 antisense plasmid efficiently inhibited Stat3 activation, increased tumor cell apoptosis, and decreased Bcl-x(L) expression in a head and neck xenograft model. These findings provide evidence that constitutively activated Stat3 is an early event in head and neck carcinogenesis that contributes to the loss of growth control by an anti-apoptotic mechanism.

Forced expression of the homeobox-containing gene Pem blocks differentiation of embryonic stem cells

Similarities in the differentiation of mouse embryos and ES cell embryoid bodies suggest that aspects of early mammalian embryogenesis can be studied in ES cell embryoid bodies. In an effort to understand the regulation of cellular differentiation during early mouse embryogenesis, we altered the expression of the Pem homeobox-containing gene in ES cells. Pem is normally expressed in the preimplantation embryo and expressed in a lineage-restricted fashion following implantation, suggesting a role for Pem in regulating cellular differentiation in the early embryo. Here, we show that the forced expression of Pem from the mouse Pgk-1 promoter in ES cells blocks the in vitro and in vivo differentiation of the cells. In particular, embryoid bodies produced from these Pgk-Pem ES cells do not differentiate into primitive endoderm or embryonic ectoderm, which are prominent features of early embryoid bodies from normal ES cells. This Pgk-Pem phenotype is also different from the null phenotype, as embryoid bodies derived from ES cells in which endogenous Pem gene expression has been blocked show a pattern of differentiation similar to that of normal ES cells. When the Pgk-Pem ES cells were introduced into subcutaneous sites of nude mice, only undifferentiated EC-like cells were found in the teratomas derived from the injected cells. The Pem-dependent block of ES cell differentiation appears to be cell autonomous; Pgk-Pem ES cells did not differentiate when mixed with normal, differentiating ES cells. A block to ES cell differentiation, resulting from the forced expression of Pem, can also be produced by the forced expression of the nonhomeodomain region of Pem. These studies are consistent with a role for Pem in regulating the transition between undifferentiated and differentiated cells of the early mouse embryo.

WISP genes are members of the connective tissue growth factor family that are up-regulated in wnt-1-transformed cells and aberrantly expressed in human colon tumors

Wnt family members are critical to many developmental processes, and components of the Wnt signaling pathway have been linked to tumorigenesis in familial and sporadic colon carcinomas. Here we report the identification of two genes, WISP-1 and WISP-2, that are up-regulated in the mouse mammary epithelial cell line C57MG transformed by Wnt-1, but not by Wnt-4. Together with a third related gene, WISP-3, these proteins define a subfamily of the connective tissue growth factor family. Two distinct systems demonstrated WISP induction to be associated with the expression of Wnt-1. These included (i) C57MG cells infected with a Wnt-1 retroviral vector or expressing Wnt-1 under the control of a tetracyline repressible promoter, and (ii) Wnt-1 transgenic mice. The WISP-1 gene was localized to human chromosome 8q24.1-8q24.3. WISP-1 genomic DNA was amplified in colon cancer cell lines and in human colon tumors and its RNA overexpressed (2- to >30-fold) in 84% of the tumors examined compared with patient-matched normal mucosa. WISP-3 mapped to chromosome 6q22-6q23 and also was overexpressed (4- to >40-fold) in 63% of the colon tumors analyzed. In contrast, WISP-2 mapped to human chromosome 20q12-20q13 and its DNA was amplified, but RNA expression was reduced (2- to >30-fold) in 79% of the tumors. These results suggest that the WISP genes may be downstream of Wnt-1 signaling and that aberrant levels of WISP expression in colon cancer may play a role in colon tumorigenesis.

Bcl-2 but not Bax expression is associated with apoptosis in normal and transformed squamous epithelium

Aberrant regulation of apoptosis may contribute to tumorigenesis. Relative levels of apoptosis regulatory proteins, such as Bcl-2 and Bax as well as interactions of these proteins with other gene products, may contribute to the rate of apoptosis in neoplasia. We examined Bcl-2 expression in 104 squamous cell carcinomas of the head and neck, as well as histologically normal mucosa several centimeters away from the tumor, and in control normal mucosa from patients without cancer. Immunohistochemistry and immunoblotting demonstrated Bcl-2 expression in 30% (31 of 104) of squamous cell carcinoma, with an increase in Bcl-2 protein levels compared with control normal mucosa from noncancer patients. Bcl-2-positive tumors demonstrated a 5-fold decrease in the number of apoptotic cells compared with Bcl-2-negative tumors. Bcl-2 protein expression was associated with poorly differentiated tumor grade but was not correlated with Bax expression or patient survival. These findings demonstrate that Bcl-2 contributes to apoptosis in normal and transformed squamous epithelium.

Inhibition of human squamous cell carcinoma growth in vivo by epidermal growth factor receptor antisense RNA transcribed from the U6 promoter

BACKGROUND

Squamous cell carcinomas of the head and neck (SCCHN), unlike normal mucosal squamous epithelial cells, overexpress epidermal growth factor receptor (EGFR) messenger RNA and protein. EGFR protein is required to sustain the proliferation of SCCHN cells in vitro. To determine whether EGFR expression contributes to tumor growth, we investigated the effect of suppressing EGFR expression in tumor xenografts through in situ expression of antisense oligonucleotides.

METHODS

Intratumoral cationic liposome-mediated gene transfer was used to deliver plasmids capable of expressing sense or antisense EGFR sequences into human head and neck tumors, which were grown as subcutaneous xenografts in nude mice. The oligonucleotides were expressed under the control of the U6 RNA promoter.

RESULTS

Direct inoculation of the EGFR antisense (but not the corresponding sense) plasmid construct into established SCCHN xenografts resulted in inhibition of tumor growth, suppression of EGFR protein expression, and an increased rate of apoptosis (programmed cell death). Sustained antitumor effects were observed for up to 2 weeks after the treatments were discontinued.

CONCLUSION

These results suggest that interference with EGFR expression, using an antisense-based gene therapy approach, may be an effective means of treating EGFR-overexpressing tumors, including SCCHN.

Levels of TGF-alpha and EGFR protein in head and neck squamous cell carcinoma and patient survival

BACKGROUND

The most accurate predictor of disease recurrence in patients treated for head and neck squamous cell carcinoma is, at present, the extent of regional lymph node metastasis. Since elevated levels of epidermal growth factor receptor (EGFR) and of its ligand, transforming growth factor-alpha (TGF-alpha), have been detected in primary tumors of patients with head and neck squamous cell carcinoma, we determined whether tumor levels of these proteins were of prognostic importance.

METHODS

Monoclonal antibodies specific for EGFR and TGF-alpha were used for immunohistochemical detection of each protein in tissue sections of primary tumors from 91 patients who were treated by surgical resection. Levels of immunoreactive EGFR and TGF-alpha were quantified by use of a computerized image analysis system and were normalized to appropriate standards. The logrank test and proportional hazards regression analysis were used to calculate the probability that EGFR and TGF-alpha levels were associated with disease-free survival (i.e., no recurrence of cancer) and cause-specific survival (i.e., patients do not die of their disease). All P values were two-sided.

RESULTS

When tumor levels of EGFR or TGF-alpha were analyzed as continuous variables, disease-free survival and cause-specific survival were reduced among patients with higher levels of EGFR (both P = .0001) or TGF-alpha (both P = .0001). In a multivariate analysis, tumor site, tumor level of EGFR, and tumor level of TGF-alpha were statistically significant predictors of disease-free survival; in a similar analysis, regional lymph node stage and tumor levels of EGFR and of TGF-alpha were significant predictors of cause-specific survival.

CONCLUSION

Quantitation of EGFR and TGF-alpha protein levels in primary head and neck squamous cell carcinomas may be useful in identifying subgroups of patients at high risk of tumor recurrence and in guiding therapy.

Downmodulation of TGF-alpha protein expression with antisense oligonucleotides inhibits proliferation of head and neck squamous carcinoma but not normal mucosal epithelial cells

Interruption of an autocrine growth pathway involving TGF-alpha and EGFR may inhibit tumor growth and improve survival in head and neck cancer patients. We previously demonstrated that biopsy specimens and established cell lines from patients with squamous cell carcinoma of the head and neck (SCCHN) overexpress TGF-alpha and its receptor, epidermal growth factor receptor (EGFR) at both the mRNA and protein levels. Protein localization studies showed that TGF-alpha and EGFR are produced by the same epithelial cells in tissues from head and neck cancer patients further supporting a role for this ligand-receptor pair in an autocrine growth pathway. To confirm that TGF-alpha contributes to autocrine growth, we examined the effect of down regulation of TGF-alpha protein on SCCHN cell proliferation. Treatment of 6 SCCHN cell lines with antisense oligodeoxynucleotides targeting the translation start site of human TGF-alpha mRNA decreased TGF-alpha protein production by up to 93% and reduced cell proliferation by a mean of 76.2% compared to a 9.7% reduction with sense oligonucleotide (range P = 0.036-0.0001). TGF-alpha antisense oligonucleotide exposure also decreased TGF-alpha protein levels in normal oropharyngeal mucosal epithelial cells, however their growth rate was not affected. These findings indicate that TGF-alpha is participating in an autocrine signaling pathway in transformed, but not in normal mucosal epithelial cells, that promotes proliferation.

Asynchronous modulation of transforming growth factor alpha and epidermal growth factor receptor protein expression in progression of premalignant lesions to head and neck squamous cell carcinoma

The development of head and neck squamous cell carcinoma occurs as a result of the accumulation of genotypic and phenotypic alterations in the upper aerodigestive tract mucosa. Up-regulation of epidermal growth factor receptor (EGFR) and its ligand, transforming growth factor alpha (TGF-alpha), have been identified previously as early events in head and neck carcinogenesis. To determine the timing of increased TGF-alpha and EGFR protein expression in the development of head and neck cancer, we examined progressive mucosal dysplasias from three distinct and complimentary patient groups: (a) samples from patients with lesions demonstrating different degrees of dysplasia (n = 22) compared with mucosa samples from gender and age-matched controls (n = 8); (b) patients with lesions demonstrating different degrees of dysplasia at a single time point (n = 3); and (c) patients who progressed over several years to invasive cancer at the site of dysplasia (n = 7). Immunohistochemical analysis with monoclonal antibodies specific for TGF-alpha and EGFR were used to detect protein expression in all specimens. Protein levels were further quantitated using a computerized image analysis system. In all three groups, we found that TGF-alpha protein levels were elevated in mild dysplasia compared with control normal mucosa and were not further modulated with increasing degrees of dysplasia. In contrast, EGFR levels were relatively low in mild dysplasia and increased with higher degrees of dysplasia. These findings indicate that up-regulation of TGF-alpha and EGFR are distinct events both chronologically and, possibly, mechanistically in the pathogenesis of head and neck squamous cell carcinoma.

Expression of p53, PCNA, and C-erbB-2 in Barrett's metaplasia and adenocarcinoma

We sought to determine if an immunohistochemical panel of p53, PCNA, and c-erbB-2 was a useful biomarker of transformation in Barrett's metaplasia. P53, PCNA, and c-erbB-2 immunohistochemistry was performed on resected Barrett's specimens selected to show discrete grades of dysplasia and then on prospectively obtained biopsies. In resection specimens, p53 was positive in 36% with no dysplasia, in 30% with low-grade dysplasia, in 85% with high-grade dysplasia, and in 90% of adenocarcinomas. While an evaluation of proliferation throughout the specimen did not differ between groups, surface proliferation was significantly higher in high-grade dysplasia than in low-grade or no dysplasia. All high-grade dysplasia specimens were positive for at least one marker, compared to 44% with no or low-grade dysplasia. C-erbB-2 was only seen in 31% with high-grade dysplasia and in 10% of adenocarcinomas. Prospectively, the panel had a sensitivity of 100%, a specificity of 81% and an overall accuracy of 83% in identifying patients who developed high-grade dysplasia or cancer. Thus, overexpression of p53 occurs early in the malignant transformation of Barrett's and increases with histologic progression, and proliferation at the surface of Barrett's epithelium increases with progressive grades of dysplasia. An immunohistochemical panel of p53 and PCNA is a useful biomarker for Barrett's metaplasia.

Inhibition of epidermal growth factor receptor gene expression and function decreases proliferation of head and neck squamous carcinoma but not normal mucosal epithelial cells

Previous reports have shown that fresh tissues and cell lines from patients with squamous cell carcinoma of the head and neck (SCCHN) overexpress transforming growth factor alpha (TGF-alpha) and its receptor, the epidermal growth factor receptor (EGFR) at both the mRNA and protein levels. Protein localization studies confirm that TGF-alpha and EGFR are produced by the same epithelial cells in tissues from head and neck cancer patients further supporting an autocrine growth pathway. Using three strategies, we examined the hypothesis that downmodulation of EGFR would reduce the proliferation of SCCHN cells. We targeted EGFR mRNA using antisense oligonucleotides and the mature EGFR protein at two sites, the ligand-binding domain and the kinase domain, and determined the effects of this targeting on SCCHN proliferation. Treatment of several SCCHN cell lines with a pair of antisense oligodeoxynucleotides directed against the translation start site and first intron-exon splice junction of the human EGFR gene resulted in decreased EGFR protein production and inhibited growth by 86% compared to a 13% reduction in cells treated with sense oligonucleotides (P=0.03). Growth inhibition was specific for carcinoma cells since the same EGFR antisense oligonucleotides had no effect on the proliferation of normal mucosa cells harvested from non-cancer patients. Two monoclonal antibodies which block ligand binding to EGFR (MAbs 425 and 528) inhibited the growth of several SCCHN cell lines by up to 97% which suggests that EGFR is participating in an autocrine pathway in SCCHN that is, at least in part, external. An EGFR-specific tyrosine kinase inhibitor (PD 153035) was found to inhibit EGFR phosphorylation in SCCHN cell lines and to reduce growth by 68% although it had no effect on the growth rate of normal mucosal epithelial cells. These experiments indicate that EGFR gene expression and function is critical for SCCHN cell growth but not for growth of normal mucosa cells and therefore may serve as a tumor-specific target for preventive and therapeutic strategies in head and neck cancer.

Tissue expression of neu differentiation factor/heregulin and its receptor complex in prostate cancer and its biologic effects on prostate cancer cells in vitro

BACKGROUND

Prostate cancer is the most common cancer in American men and the second leading cause of cancer death. All clinical observations correlate poorly differentiated high-grade prostate cancer with disease-specific mortality. The HER2 cell membrane tyrosine kinase, a member of the epidermal growth factor receptor family that is the transcription product of the erbB2neu oncogene, and HER3, a receptor protein of the same family, are overexpressed in prostate cancer and prostatic intraepithelial neoplasia. The ligand for these receptors and another related family member, HER4, has recently been identified by independent investigator groups and called neu differentiation factor (NDF) or heregulin. In vitro treatment of HER2- and HER3- or HER2- and HER4-expressing breast cancer cells stimulates tyrosine phosphorylation of HER2 and produces changes in the rate of proliferation, degree of cellular differentiation, and synthesis of physiologic secretion products. There are no published reports on the expression of NDF and HER4 in prostate cancer or the in vitro effects of NDF in prostate cancer cells.

METHODS

Expression of NDF, HER2, HER3, and HER4 was studied in 24 frozen prostatectomy specimens by immunohistochemistry. The biologic effect of human recombinant NDF was studied in vitro, using the LNCaP, PC3, and DU145 human prostate cancer cell lines. HER and NDF protein expression was studied by immunohistochemistry. NDF mRNA was analyzed using reverse transcriptase polymerase chain reaction from whole RNA. The biologic effects of NDF on prostate cancer cells in vitro included cell proliferation, thymidine synthesis, induction of prostate-specific antigen mRNA, anchorage-dependent and anchorage-independent cell growth, and ploidy analysis. Data analysis was performed using Student's t test.

RESULTS

Observations in clinical prostatectomy specimens: Immunohistochemistry studies in clinical prostatectomy specimens demonstrate absence of significant NDF expression in prostate cancer, whereas it is expressed in 100% of the stroma, 100% of basal epithelial cells, and 58% of luminal cells in normal and benign hyperplastic prostatic tissue. The HER4 receptor protein is strongly expressed by normal prostate luminal cells, but not prostate cancer. Benign prostate tissue exhibits strong expression of HER2, HER3, and HER4 by basal cells, but only luminal cells significantly express HER4. Only 23% of prostate cancer specimens express HER4, while 95% express HER3 and 82% HER2. Prostatic intraepithelial neoplasia stained similarly to cancer for all proteins studied. Observations in prostate cancer cell lines: In vitro treatment with NDF significantly reduces aneuploidy and proliferation and growth of androgen-sensitive prostate cancer cells. Incubation with NDF also induces prostate-specific antigen mRNA in prostate cancer cells. In spite of displaying NDF mRNA, prostate cancer cells do not produce detectable NDF protein, but express HER2 and HER3 proteins.

DISCUSSION

These data suggest that NDF may be a paracrine differentiation factor involved in normal adult prostate physiology and that functional loss of the NDF/HER ligand/ receptor loop may be an early event associated with prostate tumorigenesis.

Quantitative immunohistochemical analysis of transforming growth factor-alpha and epidermal growth factor receptor in patients with squamous cell carcinoma of the head and neck

BACKGROUND

Transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) mRNA are up-regulated in squamous cell carcinoma of the head and neck (SCCHN) tissues.

METHODS

Immunohistochemical staining with monoclonal antibodies to TGF-alpha and EGFR was undertaken to identify the cellular origin in tissue obtained from cancer patients and controls and to determine the correlation between mRNA expression levels and two methods of immunohistochemical evaluation.

RESULTS

TGF-alpha protein staining occurred in the suprabasal layers and spared the basal layer of normal controls. Conversely, in histologically normal mucosa from SCCHN patients, TGF-alpha was present throughout the epithelium, including the basal layer. EGFR staining was negligible in normal mucosa from control patients without cancer and relatively increased in SCCHN tissues. Increasing staining intensity was correlated with worsening dysplasia and closer proximity to the tumor. Using computerized image analysis to quantify the intensity of immunostaining, the mean optical density (MOD) of TGF-alpha staining in histologically normal mucosa (P = 0.049) and tumors (P = 0.005) from SCCHN patients was significantly higher than in control normal mucosa from noncancer patients (1.9- and 1.7-fold, respectively). EGFR MOD was also greater in the histologically normal mucosa (P = 0.009) and tumors (P = 0.006) from SCCHN patients than in control normal mucosa (1.8- and 1.9-fold, respectively). For both TGF-alpha (P = 0.668) and EGFR (P = 0.116), the MOD was similar for both tumor and histologically normal mucosa from SCCHN patients.

CONCLUSIONS

TGF-alpha and EGFR protein expression is increased early in head and neck squamous cell carcinogenesis and can be quantitated by computerized image analysis of immunohistochemical staining. Altered distribution of TGF-alpha protein in histologically normal mucosa from SCCHN patients compared with control mucosa from patients without cancer suggests a switch from a paracrine to an autocrine pathway.

Ovarian teratomas associated with the insertion of an imprinted transgene

Ovarian teratomas are tumors that arise from female germ cells and are often a mixture of immature embryonal carcinoma cells and mature embryonic cells. Tissues derived from all three primary embryonic lineages (ectoderm, mesoderm, and endoderm) are typically found in the mature elements of a teratoma. In the case of the transgenic mouse line TG.KD, created with an imprinted transgene construct, malignant ovarian teratomas of a mixed germ cell tumor morphology occur in 15-20% of hemizygous female carriers of the transgene. The tumors frequently metastasize and can result in death of the mouse. Genetic analysis indicates that the tumors are associated with the transgenes integration site. Inbred FVB/N and female mice of other transgenic lines, also created in the inbred FVB/N strain with the same DNA construct as TG.KD, do not develop teratomas. In addition to teratomas, the integration of the transgene on Chromosome (Chr) 8 is associated with a perinatal lethality in homozygous transgenic carriers. The hemizygous genotypes of the teratomas suggest that they arise from early germ cells, prior to the completion of meiosis I.

Assessment of sensitivity and specificity of immunohistochemical staining of p53 in lung and head and neck cancers

Thirty-two primary carcinomas of the lung and 17 carcinomas of the head and neck (HN) were systematically analyzed for p53 mutations in the highly conserved regions of the gene (exons 5-8). Frozen sections of the same tumors were stained immunohistochemically to assess the sensitivity and specificity of p53 expression as determined by the presence or absence of the protein. On the basis of histology, the lung tumors studied were divided into adenocarcinomas (AC; n = 15), squamous-cell carcinomas (SCC; n = 12), and large-cell carcinomas (LCC; n = 5). All the HN cancers were SCC. Mutations in the p53 gene were detected by direct sequencing of amplified polymerase chain reaction products in six AC of the lungs (40%), three SCC of the lungs (25%), and one LCC (20%), with an overall mutation frequency of 31%. Nine AC (60%) of the lungs, five SCC (42%), and four LCC (80%) were p53-positive by immunohistochemistry. Among HN cancers, p53 mutations were detected in seven tumors (41%). Nine HN tumors (53%) were positive for p53. Negative staining, despite the presence of p53 mutations, was confined to nonsense mutations with truncated p53 and to single-base mutations not causing any change in the amino acid. Although immunohistochemical staining for mutated p53 is sensitive and simple to perform as a screening method, it is not as specific for evaluation of p53 mutations in lung and HN cancers.

Elevated c-yes tyrosine kinase activity in premalignant lesions of the colon

BACKGROUND/AIMS

The cellular oncogene c-yes and its viral homologue v-yes (the transforming gene of Yamaguchi 73 and Esh avian sarcoma viruses) encode 62-kilodalton, cytoplasmic, membrane-associated, protein-tyrosine kinases. For the related Src kinase, a close correlation exists between elevated kinase activity and cell transformation. Previously, we observed elevated Yes activity in many human colon carcinomas. Colonic neoplasia provides an opportunity to study tumor progression because most carcinomas arise from adenomas, which in turn arise from normal epithelia. The malignant potential of adenomas varies with size, histology, and degree of dysplasia. Large adenomas (> or = 2 cm) with villous architecture and severe dysplasia are most likely to develop carcinoma.

METHODS

To determine whether Yes is activated in premalignant lesions of the colon, we measured its in vitro protein-tyrosine kinase activity in 21 colonic adenomas from 17 patients.

RESULTS

Activity of Yes in adenomas at greatest risk for cancer was significantly greater (12- or 14-fold as measured by enolase or autophosphorylation, respectively) than activity in adjacent normal mucosa. Moreover, villous structure, large size (> or = 2 cm), or severe dysplasia correlated with elevated Yes activity.

CONCLUSIONS

The activity of Yes is elevated in adenomas that are at greatest risk for developing cancer.

Cytokines in inflammatory malignant fibrous histiocytoma presenting with leukemoid reaction

Inflammatory malignant fibrous histiocytomas (IMFH) are rare tumors and are frequently associated with leukocytosis. In rare cases, leukemoid reactions were attributed to tumor production of unidentified hematopoietic factors. In this study, we used immunohistochemical techniques to show cytokine immunoreactivity in the malignant cells of two cases of IMFH presenting with leukemoid reactions and compared them with two malignant fibrous histocytomas, noninflammatory type. All four tumors stained positively for stem cell factor (SCF), granulocyte colony-stimulating factor (G-CSF), interleukin-2 (IL-2), IL-4, IL-5, interferon-alpha (IFN-alpha), and insulin-like growth factor-I. Other cytokines detected only in the two IMFH included IL-6, IL-7, IL-8, IFN-gamma, and keratinocyte growth factor. Granulocyte-macrophage-CSF, IL-3, and transforming growth factor-beta staining was present in one of the two IMFH tumors and was not present in the noninflammatory tumors. The immunohistochemical staining was localized to the malignant cells, suggesting deregulated cytokine expression consistent with their monocytic/histocytic origin. Expression of certain cytokines in the IMFH may account for the local inflammatory infiltrate, tumor fibrosis, and the aggressive nature of the malignant cells. We also detected elevated serum levels of SCF, G-CSF, IL-6, and tumor necrosis factor in one or both of the IMFH patients. These latter observations may explain the bone marrow hypercellularity and other paraneoplastic symptoms, including fever, malaise, and weight loss, observed in both patients. Different cytokines present in the two IMFH tumors appear to be responsible for the eosinophilic leukemoid reaction observed in one case and for the granulocytic leukemoid reaction observed in the other patient. They may also be responsible for expansion of the tumor-cell population, fibroblast proliferation, and enhanced secretion of extracellular collagen.

Cell lines from grc congenic strains of rats having different susceptibilities to chemical carcinogens

The growth and reproduction complex (grc-) strains of rats have a 70-kilobase deletion in the major histocompatibility complex (MHC)-linked grc-G/C region that is associated with embryonic death, developmental defects, and an increased susceptibility to chemical carcinogens. To study further the effects associated with the deletion, fibroblastic cell lines from grc-, grc+, and grc+/- rat embryos were developed: BIL-derived cell lines are congenic for the MHC and grc, whereas R16-derived cell lines are congenic for the grc alone. In early passages, all cell lines expressed the MHC class I antigen RT1.A, had a diploid chromosome number, and did not display anchorage-independent growth or in vivo tumorigenicity. The grc- cells [median population doubling time (PDT), 47 h] grew more slowly than the grc+ (PDT, 30.5 h) and grc+/- (PDT, 33 h) cells. All cells underwent crisis, but the crisis stage began earlier and lasted longer in the grc- cells. The established grc- cell lines (PDT, 32.5 h) grew faster than the grc+ (PDT, 48.5 h) and grc+/- (PDT, 54 h) cell lines. Two of the three BIL-derived grc- lines that survived crisis became anchorage independent in tissue culture and tumorigenic in histocompatible F1 rats (highly malignant fibrosarcomas) at passages 33 and 48, respectively; by contrast, none of the R16-derived grc- cell lines transformed. None of 8 grc+ or 8 grc+/- cell lines that survived crisis displayed anchorage-independent growth or tumorigenicity under the same conditions up to passage 50. All of the established cell lines, including the two tumorigenic ones, expressed MHC class I antigens. Southern and Northern blot analyses of BIL-derived cell lines before and after crisis showed that they all constitutively expressed H-ras and Rb and that no cell line showed rearrangement, amplification, or overexpression of c-myc, H-ras, Rb, and p53 either before or after crisis. These observations indicate that: (a) the homozygous grc- deletion is necessary but not sufficient for in vitro transformation; (b) another genetic factor(s) required for transformation is linked to, or possibly in, the MHC; and (c) passage through crisis, spontaneous transformation, or carcinogen treatment does not alter the cellular expression of MHC class I antigens or of several oncogenes and tumor suppressor genes.

Comparison of three prothrombin time and activated partial thromboplastin time reagent systems on the MLA 700 coagulation analyzer

OBJECTIVE

To determine the difference in prothrombin time (PT) and activated partial thromboplastin time (aPTT) results among three reagent systems using a single analyzer instrument.

DESIGN

Convenience sample of 100 patient specimens tested in duplicate with three reagent systems: Baxter-Dade, Pacific Hemostasis, and Organon Teknika.

SETTING

A tertiary hospital that services other institutions within a three-state area.

PATIENTS

Patients were divided into four groups: (1) normal preoperative patients who received no anticoagulants, (2) patients who received warfarin for at least the week immediately before the study, (3) patients who received heparin on the day of the testing, and (4) patients with severe liver disease accompanied by abnormal liver function tests.

MAIN OUTCOME MEASURE

Coefficients of correlation of Baxter-Dade results versus the other two systems.

RESULTS

PT values were significantly different in normal samples and in warfarin-treated patients. aPTT values were significantly different for normal patients and, for the Organon system only, for heparin-treated patients. When expressed as international normalized ratio (INR) values, taking reagent sensitivity into consideration, the results correlated well. Problems with precipitation when using Organon's system limited its practical utility.

CONCLUSION

Compatibility between a reagent system and analyzer instrument should be verified by the manufacturer of the instrument. Use of the INR format produced more accurate and comparable results, allowing safer and more effective dosage adjustments. Laboratories should convert PT and aPTT results to the INR format routinely.

Expression of the gastrin gene in the normal human colon and colorectal adenocarcinoma

Gastrin, produced in the G-cells of the gastric antrum and regulating acid secretion in the stomach, also acts as a trophic factor in the gastrointestinal tract. Because of its possible role in colon cell proliferation and differentiation, evidence for its presence in normal colorectal mucosa and adenocarcinoma was sought. Utilizing tumors and matched normal mucosa from 26 patients, mature gastrin and progastrin were studied by immunohistochemistry. In normal colonic mucosal crypts, occasional cells stained concordantly for gastrin, progastrin, and chromogranin A, suggesting that they are of neuroendocrine origin. Adenomatous polyps stained neither for gastrin nor chromogranin A. In 22 of 23 adenocarcinomas, more than 50% of tumor cells stained for gastrin and progastrin. The expected gastrin transcript was demonstrable by polymerase chain reaction and RNase protection in tumors and by polymerase chain reaction in normal mucosa. Its identity was confirmed by sequencing the polymerase chain reaction product. A larger transcript containing Intron II was present in both cancers and normal mucosa but was barely discernible in the gastric antrum. Aberrant expression of gastrin may contribute to deregulated proliferation of many colorectal carcinomas.

A major histocompatibility complex-linked locus in the rat critically influences resistance to diethylnitrosamine carcinogenesis

Major histocompatibility complex (MHC)-linked deletions in the rat are associated with defects in growth and development and increased susceptibility to chemical carcinogens. The present study maps a locus critical for determining susceptibility to diethylnitrosamine (DEN) carcinogenesis by using two groups of MHC-recombinant rats congenic for the MHC and its linked region. Resistance to DEN segregates with a locus (rcc+) that maps between RT1.E and ft, and its homozygous loss markedly increases susceptibility to DEN. Non-MHC genes do not significantly influence the susceptibility of these strains to DEN. The existence of the rcc locus adds support to our hypothesis that some genes in the MHC-linked region play a major role in both normal and abnormal growth.

Pathogenesis of pancreatic sepsis

Although pancreatic sepsis is the most common cause of major morbidity and mortality associated with acute pancreatitis, the pathogenesis of such infections is unknown. Since intraperitoneal foci of inflammation are known to promote bacterial translocation, we hypothesized that acute pancreatitis promotes bacterial translocation that leads to infection of the inflamed pancreas and peripancreatic tissues. Non-lethal acute pancreatitis was induced in rats, and the translocation of live bacteria to the pancreas, mesenteric lymph nodes, liver, and spleen was determined. The presence of orally fed fluorescent beads, sensitive inert markers of translocation, was also determined in the pancreas and mesenteric lymph nodes. Live bacteria were recovered from 33% of the pancreata of rats with acute pancreatitis but from none of the control rats. Beads were visualized in 91% of the pancreata of rats with acute pancreatitis but in none of the pancreata from control rats. Beads were not visualized in the mesenteric lymph nodes of rats with acute pancreatitis, suggesting a transperitoneal route of migration. We conclude that acute pancreatitis promotes bacterial translocation leading to transperitoneal infection of the pancreas. These results support the use of selective decontamination of the gut and peritoneal lavage for the prevention of pancreatic infections in acute pancreatitis.

Distribution of cells expressing myc proteins in human colorectal epithelium, polyps, and malignant tumors

The myc gene family encodes nuclear phosphoproteins that are thought to play a role in the control of cellular proliferation and differentiation. We have undertaken an immunohistochemical study assessing the expression of myc gene family proteins in individual cells of normal colonic mucosa, colorectal polyps, and colorectal adenocarcinomas. We screened a panel of mouse monoclonal antibodies that we raised against recombinant human c-myc and N-myc proteins for recognition of myc proteins in paraffin tissue sections. Two of these antibodies, H120C69 and H8C150, were selected for indirect immunoperoxidase staining of tissue sections from 16 normal mucosas, 24 polyps, and 30 adenocarcinomas. In normal colon, about 25% of the cells in the lower one-third of the crypts of Lieberkühn stain for myc-related protein. This distribution resembles that of proliferating cells in the crypt. Benign hyperplastic polyps resemble normal mucosa in their myc staining pattern, with about 25% of the cells positive. In adenomatous polyps, the putative precursors of adenocarcinomas, from 50 to 100% of the cells stain positively for myc protein. In these cases, stained cells extend to the luminal surface, consistent with the previously reported expansion of the proliferation zone in these lesions. All adenocarcinomas examined had increased levels of myc protein relative to normal mucosa. The tumor cells exhibited markedly heterogeneous myc staining patterns, both among different tumors and, in some cases, within a single tumor. Comparison with Ki-67 monoclonal antibody staining indicates that myc protein expression in many tumors is uncoupled from cellular proliferation. Surprisingly, we observed increased numbers of myc-expressing cells and increased levels of myc protein in histologically normal colon directly adjacent to tumor, suggesting that many colorectal carcinomas secrete growth factors that activate gene expression in neighboring normal mucosa.