Biomedical subjects

T P Pretlow

Publications and source records attributed to T P Pretlow.

At least 19 recordsLinked to original sources

PubMed2002

Aberrant P-cadherin expression is an early event in hyperplastic and dysplastic transformation in the colon.

BACKGROUND: Colorectal adenomatous and, probably, hyperplastic polyp development requires epithelial remodelling and stratification, with loss of E-cadherin expression implicated in adenoma formation. We have shown that P-cadherin, normally expressed in stratified epithelia and placenta, is aberrantly expressed in disturbed epithelial architecture associated with colitis. AIMS: (i) To investigate the role of P-cadherin in colonic polyp formation. (ii) To ascertain whether expression of P-cadherin is independent of or correlated with expression of its associated proteins--E-cadherin, beta-catenin, and gamma-catenin. (iii) To determine if P-cadherin is functional regarding catenin binding in polyps. METHODS: Expression and localisation of cadherins (E- and P-) and their associated catenins (beta- and gamma-) were determined in aberrant crypt foci (ACF), in polyps with hyperplastic morphology (hyperplastic polyps and serrated adenomas), and in adenomatous polyps by immunohistochemistry, western blotting, and mRNA in situ hybridisation. Assessment of cadherin-catenin binding was evaluated by co-immunoprecipitation. Adenomatous polyposis coli (APC) mutation was assessed in adenomatous polyps. RESULTS: P-cadherin was expressed from ACF through to hyperplastic and adenomatous polyps. Alterations in E-cadherin and catenin expression occurred later, with variant patterns in (i) ACF, (ii) hyperplastic polyps and serrated adenomas, and (iii) adenomatous polyps. P-cadherin present in adenomas was functional with regard to catenin binding, and its expression was independent of APC mutational status. CONCLUSIONS: P-cadherin is aberrantly expressed from the earliest morphologically identifiable stage of colonocyte transformation, prior to changes in E-cadherin, catenin, and APC expression/mutation. P-cadherin expression alone does not predict tissue morphology, and such expression is independent of that of associated cadherins and catenins.

Adenomatous Polyposis Coli↗

PubMed2001

Beta-catenin expression is altered in human colonic aberrant crypt foci.

The aberrant expression of beta-catenin in colon tumors and the discovery of beta-catenin mutations in small adenomas suggest that alterations of beta-catenin are early events in human colorectal carcinogenesis. Here, we describe the expression of beta-catenin in human aberrant crypt foci (ACF), the earliest identified neoplastic lesions in the colon. Paraffin-embedded sections of 94 ACF, 12 adenomas, and 10 carcinomas were evaluated for beta-catenin expression by immunohistochemistry. Normal colonic epithelial cells adjacent to these lesions showed strong membranous expression of beta-catenin and lacked cytoplasmic and nuclear expression. Cytoplasmic expression of beta-catenin was seen in 25 of 46 ACF with dysplasia and in 2 of 48 ACF with atypia. In ACF with dysplasia, reduced membranous expression of beta-catenin was associated with increased nuclear (P = 0.0013) and cytoplasmic (P = 0.0247) expression. The membranous (P = 0.0003) expression of beta-catenin was reduced, and the cytoplasmic (P = 0.0016) and nuclear (P = 0.0266) expressions increased in ACF according to their degree of dysplasia. Likewise, membranous (P = 0.0007) expression of beta-catenin was reduced, and the cytoplasmic (P = 0.0050) and nuclear (P = 0.0001) expressions increased from ACF to adenoma to carcinoma. These data suggest that ACF and their aberrant expression of beta-catenin play a role in colon tumorigenesis.

Adenoma↗

PubMed2001

Correspondence re: Y. Yamada et al., frequent beta-catenin gene mutations and accumulations of the protein in the putative preneoplastic lesions lacking macroscopic aberrant crypt foci appearance, in rat colon carcinogenesis. Cancer Res., 60: 3323-3327, 2000; and sequential analysis of morphological and biological properties of beta-catenin-accumulated crypts, provable premalignant lesions independent of aberrant crypt foci in rat colon carcinogenesis. Cancer Res., 61: 1874-1878, 2001.

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Animals↗

PubMed2001

Inducible nitric oxide synthase (iNOS) is expressed similarly in multiple aberrant crypt foci and colorectal tumors from the same patients.

Aberrant crypt foci (ACF) are the earliest identified neoplastic lesions in the colon. Aberrant expression of inducible nitric oxide synthase (iNOS or NOS2) has been documented in colorectal tumors, but expression of iNOS has not been reported in human ACF or multiple neoplastic lesions from the same patient. Immunohistochemical expression of iNOS was evaluated in 42 ACF, 14 adenomas, and 25 carcinomas and their adjacent normal mucosa. iNOS was strongly expressed in the normal colonic epithelial cells of all patients; it was markedly reduced in 21 of 42 (50%) ACF and in 14 of 25 (56%) carcinomas. The expression of iNOS was remarkably similar in multiple lesions from the same patient (P < 0.0001). These results suggest that the reduced expression of iNOS is a very early event in the development of some human colorectal tumors, and that host factors control the expression of iNOS similarly in premalignant and malignant colonic epithelial cells.

Aged↗

PubMed2000

Prostate cancer and other xenografts from cells in peripheral blood of patients.

Good models for the investigation of human prostate cancer are few. Cells from approximately 9.2-21 ml of peripheral blood from patients with metastatic prostate cancer or metastatic colon cancer were injected s.c. into nude mice. Prostate cancer from 2 of 11 patients and colon cancer from 1 of 3 patients were found to be growing as metastases in the lungs of the nude mice. To our knowledge, this is the first report of the formation of xenografts from carcinoma cells taken directly from the peripheral blood of patients. Expanding circulating cancer cells with this approach may have important translational applications including: (a) development of models of human cancers; and (b) sampling of cancers from specific patients for novel molecular and therapeutic approaches.

Animals↗

PubMed2000

Loss of fragile histidine triad expression in colorectal carcinomas and premalignant lesions.

Abnormal expression of the fragile histidine triad (FHIT) candidate tumor suppressor gene has been observed in a variety of human tumors, but little is known about its expression during colorectal tumorigenesis. Sections of 70 aberrant crypt foci (ACF), 55 adenomas, 84 primary colorectal carcinomas, and 13 metastatic lesions were evaluated immunohistochemically for Fhit expression. All normal colonic epithelium showed a strong expression of Fhit; 44% of carcinomas showed a marked loss or absence of Fhit expression. The proportion of carcinomas with reduced expression showed an increasing trend (a) with decreasing differentiation and (b) in tumors with metastases (62%) compared with tumors without metastases (38%). The proportion of metastatic lesions (12 of 13) with reduced expression of Fhit was even greater. Although only a small proportion of ACF and adenomas showed a reduction of Fhit expression, the reduced expression of Fhit was strongly associated with the degree of dysplasia in both ACF (P = 0.0002) and adenomas (P = 0.0085). The findings of reduced expression of Fhit in a small proportion of colonic precancerous lesions and in increased proportions of primary and metastatic colorectal cancers suggest that Fhit plays a role in the development and progression of some colon carcinomas.

Acid Anhydride Hydrolases↗

PubMed1999

Molecular cytogenetic studies of a serially transplanted primary prostatic carcinoma xenograft (CWR22) and four relapsed tumors.

BACKGROUND: Established cell lines or xenografts from prostatic carcinoma have been infrequently studied cytogenetically. CWR22 and CWR22-R are xenografts that are unique in offering one strongly androgen-dependent and several relapsed strains of a human prostate cancer that can be investigated in the laboratory. We report on the cytogenetic characterization of the hormone-dependent CWR22, and the relapsed CWR22-R serially transplanted xenografts, in our laboratory. METHODS: We utilized a suspension harvest of the xenograft tissue to optimize our yield for metaphase chromosome studies and analyzed the hormone-dependent CWR22 and four relapsed CWR22-R xenografts. These studies were accomplished using standard G-banded analysis and fluorescence in situ hybridization (FISH). A variety of DNA probes including alpha-satellite DNA probes, and chromosomal libraries, were utilized for the FISH analysis. RESULTS: Utilizing both standard cytogenetic analysis and FISH studies we have more precisely defined the CWR22 xenograft: 49,XY,+i(1)(q10),-2, der(4)t(2;4)(p21;q33), +7,+8,+12[7]/50,XY,idem, +der(2)t(2;4)(p21;q33)del(2)(q13q33)[13]. Four relapsed xenografts, CWR22R-2152, CWR22R-2524, CWR22R-2274, and CWR22R-2272 were also studied. Each of these lines demonstrated a different karyotype. CONCLUSIONS: The CWR22 karyotype offers the simplest reported karyotype for a prostate cancer tissue culture cell line or xenograft; this makes CWR22 an attractive candidate for studies of genetic changes associated with the relapse of prostate cancer treated with androgen withdrawal. Four separate, serially transplanted, relapsed CWR22-R xenografts were detected, each with a separate karyotype.

Androgens↗

PubMed1999

The identification of monoclonality in human aberrant crypt foci.

Malignant neoplasms, including colon cancers, are thought to arise from a single initiated progenitor cell. Aberrant crypt foci (ACF) are putative precursors of at least some colon cancers. The pattern of X chromosomal inactivation, which is identified by the differential methylation of a site near a polymorphic CAG repeat in the androgen receptor gene, was used to determine the clonality status of 11 ACF from eight female patients. Ten of 11 ACF were found to be monoclonal aberrations. The eleventh ACF appeared monoclonal, but nonrandom inactivation of the X chromosome was also seen in normal crypts from this patient. These results clearly demonstrate that: (a) a high percentage of ACF lesions are neoplastic rather than hyperplastic; and (b) ACF are the earliest identified neoplastic lesions in the colon.

Chromosome Aberrations↗

PubMed1998

Altered expression of RET proto-oncogene product in prostatic intraepithelial neoplasia and prostate cancer.

BACKGROUND: The RET proto-oncogene encodes a protein that belongs to the tyrosine kinase growth factor receptor family. Germline point mutations in RET are found in individuals with multiple endocrine neoplasia (MEN) syndromes, and gene rearrangements have been reported in papillary thyroid cancers. We recently identified transcripts of the RET proto-oncogene in human prostate cancer xenografts and prostate cancer cell lines by means of reverse transcription-polymerase chain reaction analyses. The purpose of this study was to investigate Ret protein expression in human prostate tissue. METHODS: Ret protein expression was evaluated immunohistochemically in formalin-fixed, paraffin-embedded whole-prostate sections. The prostate specimens were obtained from 30 patients with prostate cancer after radical prostatectomies. Ret protein expression was compared in tumor foci and benign prostatic tissue. Medullary thyroid carcinoma tissue associated with an MEN syndrome and papillary thyroid cancer tissue served as positive controls. RESULTS: Ret appeared to be overexpressed in high-grade (histopathologically advanced) prostatic intraepithelial neoplasia (PIN) and prostate cancer when compared with its expression level in benign prostatic secretory epithelium. In addition, there was an apparent increase in Ret protein expression with decreased cellular differentiation, i.e., increasing Gleason pattern. CONCLUSION: Expression of the RET proto-oncogene in benign prostatic epithelium, high-grade PIN, and histopathologically advanced prostate cancer suggests that RET may play a role in the growth of both benign and neoplastic prostate epithelial cells.

Drosophila Proteins↗

PubMed1998

Putative preneoplastic changes identified by enzyme histochemical and immunohistochemical techniques.

Microscopic evaluation of whole-mount colons stained with methylene blue and/or hexosaminidase has identified putative preneoplastic lesions in the colons of rodents treated with carcinogen and in the grossly normal colons of humans. Enzyme histochemistry with glycol methacrylate sections has permitted the identification of putative premalignant lesions in rodent livers, human and rodent colons, and human prostates. Immunohistochemistry with paraffin-embedded tissues has been used to identify and characterize putative premalignant lesions in human colons and prostates.

Animals↗

PubMed1997

Identification of dysplasia in human colonic aberrant crypt foci.

Aberrant crypt foci (ACF) are grossly invisible putative premalignant lesions in the colon. As dysplasia is considered an important precursor of colon carcinoma, we wanted to determine the presence and severity of dysplasia in human ACF. Fifty ACF from 28 patients were embedded in paraffin, cut serially, and stained with hematoxylin and eosin. Multiple slides from each ACF were evaluated for dysplasia according to a defined set of criteria. Of 50 ACF, 3 (6%) contained focal areas with severe dysplasia, ie, carcinoma in situ, 4 (8%) contained focal areas with moderate dysplasia, and 20 (40%) contained focal areas with mild dysplasia. Twenty-three ACF (46%) contained no detectable dysplasia. In 15 of 27 ACF with dysplasia, less than 50% (eg, 4 of 28, 10 of 54, and 10 of 30 sections) of the sections cut and evaluated from each ACF demonstrated dysplasia. The presence of dysplasia in a large proportion of ACF supports the hypothesis that they may be precarcinomatous.

Adult↗

PubMed1996

CWR22: the first human prostate cancer xenograft with strongly androgen-dependent and relapsed strains both in vivo and in soft agar.

Most patients' prostate cancers respond to androgen deprivation but relapse after periods of several months to years. Only two prostate cancer xenografts, LNCaP and PC-346, have been reported to be responsive to androgen deprivation and to relapse subsequently. Both of these tumors shrink slightly, if at all, and relapse less than 5 weeks after androgen withdrawal. After androgen withdrawal, the human primary prostate cancer xenograft CWR22 regresses markedly, and prostate-specific antigen (PSA) falls up to 3000-fold in the blood of mice. PSA usually returns to normal. In some animals, the tumor relapses and is then designated CWR22R. In these animals, PSA starts to rise approximately 2-7 months, and tumor begins to grow 3-10 months after castration. Animals with CWR22 need to be euthanized because of large tumors 6-12 weeks after the transplantation of CWR22. Androgen withdrawal prolongs life approximately 3-4-fold.

Agar↗

PubMed1996

Evidence for genomic instability in human colonic aberrant crypt foci.

Aberrant crypt foci (ACF) are morphologically abnormal structures that can be identified in whole amounts of colonic tissue from rodents treated with colon carcinogens and from patients at risk for development of colon tumors. ACF are heterogeneous and exhibit properties, such as altered patterns of cell proliferation, the presence of dysplasia, and mutations in protooncogenes and tumor formation. In this study, we have investigated the presence of genomic instability in DNA isolated from human ACF from patients with colon cancer. Altered allele length detected by electrophoretic separation of PCR amplified oligo A or microsatellite loci was used to identify candidate samples which were then more rigorously investigated by sequence analysis for instability. Of 20 patients examined, two exhibited alterations at two loci, and this instability could be confirmed by sequence analysis. An additional seven of the 20 patients had evidence for instability at a single locus. Quantitative sequence analysis of the DNA from an ACF of one of these seven patients was consistent with alteration of allele length in this patient, but the alteration was not sufficiently different from normal to reach statistical significance. Thus, genomic instability, manifest as altered length of microsatellite and oligo A sequences, in present in some ACF, and therefore can be a very early event in the development of some human colon cancers.

Adult↗

PubMed1996

Acetylator genotype (NAT2)-dependent formation of aberrant crypts in congenic Syrian hamsters administered 3,2'-dimethyl-4-aminobiphenyl.

Some but not all human epidemiological studies suggest a higher incidence of colon cancer in rapid acetylator individuals. Aberrant crypts, the earliest morphologically evident preneoplastic lesions in chemical colon carcinogenesis, were measured in rapid and slow acetylator congenic Syrian hamsters administered 3,2' -dimethyl-4-aminobiphenyl, an aromatic amine colon carcinogen, to investigate the specific role of the acetylator genotype (NAT2) in colon carcinogenesis. Age-matched rapid (Bio. 82.73/H-Patr) and slow (Bio. 82.73/ H-Pat(s) acetylator female Syrian hamsters congenic at the NAT2 locus received a s.c. injection of 3,2' -dimethyl-4-aminobiphenyl (100 mg/kg) at the start of weeks 1 and 2. After 10 and 14 weeks, the hamsters were sacrificed, and each whole cecum, colon, and rectum was stained with 0.2% methylene blue, fixed in 4% paraformaldehyde, and examined under a dissecting microscope for the presence of aberrant crypts. Aberrant crypts were identified in the cecums and colons of both rapid and slow acetylator congenic hamsters treated with 3,2' -dimethyl-4-aminobiphenyl but not in vehicle controls. The size of the aberrant crypt foci was larger in the colon than in the cecum, and the highest frequency of aberrant crypt foci was observed in the cecum. No aberrant crypts were detected in the rectum. The frequency of aberrant crypt foci was significantly higher (2-3-fold) in rapid versus slow acetylator congenic hamsters in both cecum (P = 0.0352) and colon (P = 0.0006). These results support human epidemiological studies that suggest the rapid acetylator genotype is associated with higher risk of colon cancer induced by aromatic amines.

Acetylation↗

PubMed1996

Human aberrant crypt foci with carcinoma in situ from a patient with sporadic colon cancer.

Aberrant crypt foci are putative preneoplastic lesions found in the colons of carcinogen-treated rodents and at an increased frequency in humans at increased risk for colon cancer. There is a strong association between aberrant crypt foci and colon cancer, including many shared phenotypic and genetic alterations. The aim of this study is to present further evidence of a relationship between aberrant crypt foci and colon cancer in humans. Multiple aberrant crypt foci from a single patient were identified in unembedded colonic mucosa. Histological sections of the aberrant crypt foci and adjacent mucosa were evaluated for dysplasia, proliferative activity, and pigment-laden macrophages that were characterized with histochemical techniques. The first patient with sporadic colon cancer identified with aberrant crypt foci with carcinoma in situ is described. It is interesting that this 99-year-old patient had multiple carcinomas in situ, pseudomelanosis coli, and two metachronous colon cancers. These data lend support to the hypothesis that aberrant crypt foci are precursors of some colon cancers.

Aged↗

PubMed1996

Altered expression of CD44 in human prostate cancer during progression.

There is a great need for markers that distinguish slowly progressive from rapidly progressive prostate cancers in paraffin-embedded tissues. CD44, an adhesion molecule that has been useful for the prediction of prognosis in some other cancers, has not been described in prostate cancer. The expression of CD44 was investigated with the monoclonal antibody GKW.A3 in prostate cancer in formalin-fixed, paraffin-embedded tissue sections of (1) whole prostates from 50 patients with 74 prostate cancers; and (2) lymph node metastases from 14 patients. Sixty percent of primary prostate cancers expressed CD44 moderately to strongly. No metastases expressed CD44 moderately to strongly; only 14% of metastases expressed even low levels of immunohistochemically detectable CD44. There is a difference between primary and metastatic prostate cancer (P <.0006) in the expression of CD44 and an inverse correlation (P <.05) between histological differentiation (Gleason grade) and the expression of CD44. The magnitude of the differential expression of CD44 in primary and metastatic prostate cancers suggests it should be investigated as an indicator of prognosis in a large prospective study.

Disease Progression↗

PubMed1996

Expression of E-cadherin in primary and metastatic prostate cancer.

Immunohistochemical studies have suggested that E-cadherin may be a useful prognostic marker in prostate cancer. Previous studies have depended on cryostat sections of tissues selected grossly. Many prostate cancers, even when extensive, are not visible grossly; many others cannot be demarcated sharply grossly. The wide applicability of prognostic markers after total prostatectomy will depend upon methods that can be applied to tissue selected based upon the histopathological examination of the entire prostate. Our purpose was to investigate the possibility that E-cadherin could be demonstrated in paraffin-embedded whole prostates and metastatic prostate cancer. Microwaving in citrate buffer was the best of five methods tested for the demonstration of E-cadherin in paraffin-embedded prostate and was used to investigate 53 primary prostate cancers from 44 patients and lymph node metastases from 14 patients. Metastases of prostate cancer to lymph nodes expressed less (P = 0.008) E-cadherin than primary prostate cancers. The expression of E-cadherin correlated with the histopathological differentiation (Gleason grade) of primary prostate cancers (P = 0.03, Ptrend = 0.003). The use of monoclonal anti-human E-cadherin (HECD-1) with microwaving in citrate buffer followed by immunoperoxidase staining with heavy metal enhancement for the demonstration of E-cadherin in paraffin-embedded tissue will, for the first time, allow the use of archival tissue for prognostic studies of E-cadherin in prostate cancer and other tissue. Our results are consistent with the hypothesis that aggressive prostate cancers exhibit decreased expression of E-cadherin and demonstrate the feasibility of long-term prognostic studies of this molecule in the usually multiple prostate cancers found in whole, formalin-fixed, paraffin-embedded resected prostates.

Antibodies, Monoclonal↗

PubMed1995

Organ culture of benign, aging, and hyperplastic human prostate.

Organ culture of the human prostate began in the 1970s and was modeled after the work of Lasnitzki and her collaborators in the mouse two decades earlier. In organ culture of human prostates, one sees a rapid increase in epithelial cells and decrease in stromal cells during the first 3-5 days of culture. While modulation of many phenotypic properties occurs, these cultures provide a simple and rapid way to achieve large numbers of human prostatic epithelial cells in cultured tissues that are markedly depleted of stromal cells. There is some evidence that organ cultures are maintained in slightly better functional states in the presence of androgens; however, most of this evidence is less than quantitative. Most organ culture of prostates has been accomplished with tissues from unspecified locations within the prostate; interpretation of cultures carried out in this fashion has been less complete than would have been possible if they had been carried out from specific anatomic locations within the prostate. Careful pathological characterization of locations contiguous to the cultured tissue is mandatory if cultures are to be interpreted meaningfully.

Forecasting↗