Hyperplastic Proliferation Research Articles

Mucinous hidradenoma: a report of three cases

Mucinous cutaneous adnexal tumors are an uncommon occurrence. We describe three cases of mucinous hidradenoma characterized by diffuse and prominent mucinous cell proliferation and discuss the relevant literature. The patients (two men and one woman) ranged in age from 32 to 72 years. The lesions were completely excised, and all patients were alive without evidence of disease (follow-up interval 3-4 years). Case 1 presented as a 1.3-cm eyelid nodule and histology showed a mucinous apocrine hidradenoma with a proliferation of mucinous cells and apocrine glands. Case 2, from the shoulder of a 40-year-old man, was a 2.5-cm well-circumscribed nodule composed of hyperplastic villoglandular proliferation of mucinous cells with focal squamous whorls and focal columnar glandular cells showing decapitation secretion. The tumor was also interpretated as a mucinous hidradenoma, most likely of follicular-apocrine origin. Case 3 was a 3.0-cm scalp nodule. The histology showed a mucinous clear-cell hidradenoma composed of numerous mucinous glands amidst small squamous cells with clear cytoplasm and a hyalinized fibrovascular stroma.

Western array analysis of cell cycle protein changes during the hyperplastic to hypertrophic transition in heart development

Cardiac myocytes proliferate most rapidly during the hyperplastic phase of heart development; however, the level of cell cycle activity is drastically down regulated after birth. Further growth of the heart is achieved by hypertrophic growth of cardiac myocytes. The mechanism that controls the switch from hyperplastic proliferation to hypertrophic growth in cardiac myocytes is unknown. Understanding this fundamental mechanism of cardiac myocyte biology would be most beneficial for studies directed towards myocardial regeneration. In this study, we identified changes in the expression of proteins involved in cell cycle regulation during the hyperplastic to hypertrophic transition of cardiac myocytes. Using a high-throughput immunoblotting technique, we examined 200+ proteins in primary cultures of cardiac myocytes at different developmental time points to determine the important regulators of this transition. In addition, we also analyzed samples from an immortalized cardiac myocyte cell line to compare expression levels of cell cycle regulatory proteins to our primary cultures. Our findings by this uncovered proteomic screen identified several potential key regulatory proteins and provide insight into the important components of cardiac myocyte cell cycle regulation.

Loss of the retinoblastoma tumor suppressor: differential action on transcriptional programs related to cell cycle control and immune function.

Functional inactivation of the retinoblastoma tumor suppressor gene product (RB) is a common event in human cancers. Classically, RB functions to constrain cellular proliferation, and loss of RB is proposed to facilitate the hyperplastic proliferation associated with tumorigenesis. To understand the repertoire of regulatory processes governed by RB, two models of RB loss were utilized to perform microarray analysis. In murine embryonic fibroblasts harboring germline loss of RB, there was a striking deregulation of gene expression, wherein distinct biological pathways were altered. Specifically, genes involved in cell cycle control and classically associated with E2F-dependent gene regulation were upregulated via RB loss. In contrast, a program of gene expression associated with immune function and response to pathogens was significantly downregulated with the loss of RB. To determine the specific influence of RB loss during a defined period and without the possibility of developmental compensation as occurs in embryonic fibroblasts, a second system was employed wherein Rb was acutely knocked out in adult fibroblasts. This model confirmed the distinct regulation of cell cycle and immune modulatory genes through RB loss. Analyses of cis-elements supported the hypothesis that the majority of those genes upregulated with RB loss are regulated via the E2F family of transcription factors. In contrast, those genes whose expression was reduced with the loss of RB harbored different promoter elements. Consistent with these analyses, we found that disruption of E2F-binding function of RB was associated with the upregulation of gene expression. In contrast, cells harboring an RB mutant protein (RB-750F) that retains E2F-binding activity, but is specifically deficient in the association with LXCXE-containing proteins, failed to upregulate these same target genes. However, downregulation of genes involved in immune function was readily observed with disruption of the LXCXE-binding function of RB. Thus, these studies demonstrate that RB plays a significant role in both the positive and negative regulations of transcriptional programs and indicate that loss of RB has distinct biological effects related to both cell cycle control and immune function.

Cholangiocarcinoma cells are susceptible to the modulation of cell growth by endogenous opioid peptides but respond with increased proliferation

Cholangiocarcinoma is the malignancy arising from cholangiocytes. If and how hyperplastic and malignant cholangiocyte proliferation differ in terms of response to endogenous factors that modulate cell growth is still obscure. Cholangiocytes express both delta (DOR) and mu (MOR) opioid receptors. Endogenous opioid peptides markedly inhibit hyperplastic cholangiocyte proliferation in an autocrine/paracrine fashion, by DOR activation. In contrast, hyperplastic cholangiocytes are minimally sensitive to the pro-proliferative activation of MOR.

CGH of microdissected Kaposi's sarcoma lesions reveals recurrent loss of chromosome Y in early and additional chromosomal changes in late tumour stages

It is still unclear if Kaposi's sarcoma (KS) is a monoclonal cell proliferation or a polyclonal, hyperplastic, reactive process. Reports on KS cytogenetics are few and restricted to late stage disease and cell lines. We analysed 27 KS, early and late, AIDS related (AKS) and endemic (EKS) by laser microdissection, global DNA amplification and comparative genomic hybridization (CGH). Loss of Y chromosome was detected in 20/23 male KS, which was the only recurrent chromosomal aberration in all nine male early (patch) KS. Only one patch EKS showed in addition to the Y loss a loss of Xq. Late (nodular) AKS and EKS showed recurrent copy number changes in chromosomes 16, 17, 21, X and Y, as well as other random changes. The loss of chromosome 16, 17 and Y was confirmed by interphase fluorescence in situ hybridization (FISH) on paraffin sections. EKS showed a higher number of chromosomal abnormalities than AKS, indicating that rapid growth of AKS is less dependent on genetic changes than is EKS, possibly because of the immunosuppressed host environment in AKS. Clonal loss of chromosome Y was detected in all early male KS, while additional chromosomal aberrations appeared during development to late KS. This increase in chromosomal abnormalities during tumour growth indicates genetic instability and the selection of survival cell clones establishing late, aggressive sarcoma growth. Our data support the view that KS (in males) develops into a clonal tumour yet initially is a hyperplastic reactive cell proliferation.

Assessment of toxicity and clastogenicity of sterigmatocystin in Egyptian Nile tilapia

The increasing presence of genotoxic pollutants in the aquatic environment has led to the development of quick monitoring methods. Sterigmatocystin (Stg) is closely related to mycotoxins and has the carcinogenic potency in the experimental animal models. The exposure to genotoxic agents will give rise to alterations of DNA structure that can lead to abnormal changes of DNA fingerprints. Therefore, we have applied the random amplified polymorphism DNA (RAPD) method to evaluate the genotoxic effects of Stg and to determine if the Egyptian montmorillonite (EM) has a protective effect against Stg. The experiment was conducted in vivo to evaluate the ability of EM at a level 0.5 mg/kg body weight (bw) to prevent the toxicity and genotoxicity induced by Stg in the Nile tilapia fish. Fishes were orally administrated with EM in corn oil with or without Stg (1.6 ig/kg bw) twice a week for 4 weeks. Blood and tissue samples were collected at the end of the treatment. The results revealed that Stg had genotoxic and toxicopathological effects in Oreochromis niloticus fish. The genotoxic effects were indicated by appearance of some changes in polymorphism band patterns including lost of stable bands or occurrence of new bands. There also exists a distinct distance between the band patterns of exposed fish and protected or control fish samples. The effects on the tissues were manifested by different histopathological lesions in different organs including hyperplastic proliferation of branchial epithelium, necrobiotic changes in hepatic tissue and destruction of components of the spleen. These responses were virtually abolished or markedly decreased when fishes were exposed to EM combined with Stg. It could be conclude that addition of EM resulted in the inhibition of the toxicity and clastogenicity of Stg

Evidence of a polyclonal nature of myositis ossificans

Myositis ossificans is a localized, self-limiting, reparative lesion that is composed of reactive hypercellular fibrous tissue and bone. Although it is clearly a benign lesion, its clinical, radiological, and histological appearance may sometimes mimic a malignant tumor. Whether myositis ossificans represents a monoclonal or polyclonal hyperplastic proliferation is not yet known. To address this question, we therefore extracted DNA from the respective paraffin-embedded tumor tissues of nine women with a median age of 50 years at diagnosis (range: 20-84 years) and studied the X inactivation pattern by means of methylation-sensitive polymerase chain reaction and primers that target the polymorphic CGG trinucleotide repeat of the FMR1 gene. The fact that we did not detect any skewing of the X inactivation pattern in the five successfully analyzed cases corroborates the notion that myositis ossificans results from a polyclonal proliferation and confirms that it is a reactive, reparative process. Analysis of the X inactivation pattern may, thus, supplement the differential diagnostic work-up of cases with an uncertain histology, at least in the informative proportion of female patients.

ENDOSCOPIC TREATMENT FOR THE BENIGN BILIARY STRICTURE IN THE PATIENT WITH CHRONIC PANCREATITIS

ABSTRACTIn some patients with chronic pancreatitis (CP), strictures are observed in the intrapancreatic bile ducts due to fibrosis and inflammation in the pancreas. Normally, even when biliary strictures exist, obstructive jaundice is rarely observed. It seemed that obstructive jaundice was brought about by temporary pancreatitis due to immoderate alcohol ingestion, followed by the aggravation of the intrapancreatic biliary stricture. When immoderate alcohol ingestion is incriminated for the pancreatic disorder, the patient should be strictly instructed to abstain from alcohol, but failure to observe this instruction seems to render endoscopic biliary stenting ineffective. When CP is complicated with pancreatolithiasis, stone fragmentation using extracorporeal shock wave lithotripsy (ESWL) is effective, and combination with endoscopic lithotomy makes it possible to remove pancreatic stones in the main pancreatic duct (MPD). To treat the beside dilating stricture of the MPD, balloon dilation and pancreatic duct stenting are performed. We obtained good results with 10 Fr pancreatic duct stents, but biliary strictures are better treated with a combination of these methods. When 10 Fr or larger straight biliary stents are used, they may be dislodged or stray if the bile duct is sharply curved. To prevent this accident we have used 10 Fr double layer stents and obtained good results. In patients with benign biliary strictures, stents are temporarily placed and should be removable. Some cases have been reported where Wallstent gave good results in a short period, but the stents were occluded due to hyperplastic proliferation of the biliary epithelium. Metal stents are not considered desirable for benign biliary strictures. Our results seem to support the assumption that benign biliary strictures are improved with 10 Fr or larger biliary stents while exercizing care to keep the patient abstinent from alcohol and performing ESWL and endoscopic treatment for CP.

Multiple endocrine neoplasia (MEN)-associated tumours

The pathological changes of tumours associated with the two main MEN syndromes, types 1 and 2, and their relation with the genetic defects responsible for the individual syndromes are reviewed. MEN 1-associated tumours, affecting mainly the pituitary, the parathyroids and the pancreas, are due to inactivation of the MEN 1 oncosuppressor gene located in 11q13. Although at least one peculiar phenotype of MEN 1 syndrome is known, no genotype–phenotype relation has been disclosed. MEN 2-associated tumours, affecting mainly the thyroid C cells, the parathyroids and the adrenal medulla, are due to oncogenic point mutations of the RET proto-oncogene located in 10q11.2. The two main phenotypes of the MEN 2 syndrome, known as MEN 2A and MEN 2B, are associated with different mutations of the RET oncogene, mostly located on exons 10 or 11 in MEN 2A and in codon 918 of exon 16 in MEN 2B. Independent of the type of MEN disease, the development of tumours follows a substantially similar pattern in all MEN target organs. The initial lesion is a diffuse hyperplastic proliferation of the affected endocrine tissue with bilateral involvement of pair organs, followed by development of multiple micro- and, eventually, macronodular lesions. Such association of endocrine hyperplastic changes and tumours is suggestive of a MEN condition in patients with apparently sporadic tumours. LOH investigations in MEN 1 cases indicate that each multiple tumour is the result of an independent genetic event.

Increase in the number of integrinβ1-immunoreactive monocyte-lineage cells in experimentally-induced adenomyosis in mice

Uterine adenomyosis is a disease in which hyperplastic endometrial stroma and glands invade the myometrium. We have previously demonstrated that hyperprolactinemia leads to the development of adenomyosis in mice. In the present study, a subtracted cDNA library was made by suppression subtractive hybridization to find specific genes that are abundantly expressed in the adenomyotic but not normal tissue in mice. A cDNA fragment of integrinβ1 (iβ1) was found in the library, and the expression of the gene product was increased in the adenomyotic uteri at mRNA and protein levels. Intense iβ1-immunoreactivity was localized on a group of cells dispersing throughout the endometrial stroma. The number of iβ1-immunoreactive (iβ1-ir) cells was significantly greater in the uteri of mice with adenomyosis than normal mice. The majority of the iβ1-ir cells expressed CD14-ir signal, a marker for monocyte-lineage cells, whereas an increase in the number of CD14-ir cells was also evident in the adenomyotic uteri, especially in the ectopic endometrial tissue. Thus, the adenomyotic stromal tissue contained numerous monocyte-lineage cells with higher expression levels of iβ1, one of their products. The relationship between the increased number of monocyte-lineage cells and the hyperplastic proliferation of endometrial tissues was discussed with a view to understanding the progressive mechanism of adenomyosis.

The Phenotype of Hurthle and Warthin-like Papillary Thyroid Carcinomas Is Distinct From Classic Papillary Carcinoma as to the Expression of Retinoblastoma Protein and E2F-1 Transcription Factor

Retinoblastoma protein plays an important role in controlling cell cycle progression. The active form of retinoblastoma protein binds to E2F-1 and inhibits transcription of S phase genes. Overexpression of E2F-1 has been suggested as an important factor in carcinogenesis. The Hurthle cell (HPCA) and Warthin-like (WLPCA) variants of papillary carcinoma are two closely related entities that arise in association with Hashimoto's thyroiditis and share the presence of oxyphilic changes in the lining of epithelial cells and the presence of papillary nuclear features. The current study included formalin-fixed, paraffin-embedded tissues from 58 cases of thyroid papillary carcinoma: 20 HPCA, 6 WLPCA, 22 conventional papillary carcinomas (PCA), and 10 follicular variants of papillary carcinoma (FVPCA). The immunohistochemical studies were performed for retinoblastoma (Rb-1) and E2F-1, (KH95) after heat-induced epitope retrieval. None of the PCA or FVPCA cases were in the positive range for Rb-1. All cases of HPCA and WLPCA of the thyroid showed reactivity in 50% or more of the nuclei in the neoplastic cell population. As for E2F-1, all cases of HPCA and WLPCA showed positive reactivity, whereas none of the PCA or FVPCA cases were in the positive range. In conclusion, HPCA and WLPCA are Rb-positive and E2F-1-positive; PCA and FVPCA are Rb-negative and E2F1-negative. Hurthle metaplastic epithelium in Hashimoto's thyroiditis is Rb-positive and E2F-1-negative. This phenotypic difference is also helpful in distinguishing hyperplastic Hurthle cell proliferation in Hashimoto's thyroiditis from HPCA or WLPCA.

Hepatocyte growth factor is elevated in chronic lung injury and inhibits surfactant metabolism.

Adult respiratory distress syndrome may incorporate in its pathogenesis the hyperplastic proliferation of alveolar epithelial type II cells and derangement in synthesis of pulmonary surfactant. Previous studies have demonstrated that hepatocyte growth factor (HGF) in the presence of serum is a potential mitogen for adult type II cells (R. J. Panos, J. S. Rubin, S. A. Aaronson, and R. J. Mason. J. Clin. Invest. 92: 969-977, 1993) and that it is produced by fetal mesenchymal lung cells (J. S. Rubin, A. M.-L. Chan, D. P. Botarro, W. H. Burgess, W. G. Taylor, A. C. Cech, D. W. Hirschfield, J. Wong, T. Miki, P. W. Finch, and S. A. Aaronson. Proc. Natl. Acad. Sci. USA 88: 415-419, 1991). In these studies, we expand on this possible involvement of HGF in chronic lung injury by showing the following. First, normal adult lung fibroblasts transcribe only small amounts of HGF mRNA, but the steady-state levels of this message rise substantially in lung fibroblasts obtained from animals exposed to oxidative stress. Second, inflammatory cytokines produced early in the injury stimulate the transcription of HGF in isolated fibroblasts, providing a plausible mechanism for the increased amounts of HGF seen in vivo. Third, HGF is capable of significantly inhibiting the synthesis and secretion of the phosphatidylcholines of pulmonary surfactant. Fourth, HGF inhibits the rate-limiting enzyme in de novo phosphatidylcholine synthesis, CTP:choline-phosphate cytidylyltransferase (EC 2.7.7.15). Our data indicate that fibroblast-derived HGF could be partially responsible for the changes in surfactant dysfunction seen in adult respiratory distress syndrome, including the decreases seen in surfactant phosphatidylcholines.

Epithelial cell adhesion molecule (Ep-CAM) modulates cell-cell interactions mediated by classic cadherins.

The contribution of noncadherin-type, Ca2+-independent cell-cell adhesion molecules to the organization of epithelial tissues is, as yet, unclear. A homophilic, epithelial Ca2+-independent adhesion molecule (Ep-CAM) is expressed in most epithelia, benign or malignant proliferative lesions, or during embryogenesis. Here we demonstrate that ectopic Ep-CAM, when expressed in cells interconnected by classic cadherins (E- or N-cadherin), induces segregation of the transfectants from the parental cell type in coaggregation assays and in cultured mixed aggregates, respectively. In the latter assay, Ep-CAM-positive transfectants behave like cells with a decreased strength of cell-cell adhesion as compared to the parental cells. Using transfectants with an inducible Ep-CAM-cDNA construct, we demonstrate that increasing expression of Ep-CAM in cadherin-positive cells leads to the gradual abrogation of adherens junctions. Overexpression of Ep-CAM has no influence on the total amount of cellular cadherin, but affects the interaction of cadherins with the cytoskeleton since a substantial decrease in the detergent-insoluble fraction of cadherin molecules was observed. Similarly, the detergent-insoluble fractions of alpha- and beta-catenins decreased in cells overexpressing Ep-CAM. While the total beta-catenin content remains unchanged, a reduction in total cellular alpha-catenin is observed as Ep-CAM expression increases. As the cadherin-mediated cell-cell adhesions diminish, Ep-CAM-mediated intercellular connections become predominant. An adhesion-defective mutant of Ep-CAM lacking the cytoplasmic domain has no effect on the cadherin-mediated cell-cell adhesions. The ability of Ep-CAM to modulate the cadherin-mediated cell-cell interactions, as demonstrated in the present study, suggests a role for this molecule in development of the proliferative, and probably malignant, phenotype of epithelial cells, since an increase of Ep-CAM expression was observed in vivo in association with hyperplastic and malignant proliferation of epithelial cells.

Monoclonal origin of multicentric Kaposi's sarcoma lesions.

Kaposi's sarcoma has features of both hyperplastic proliferation and neoplastic growth. Multiple lesions, in which spindle cells are prominent, often arise synchronously over widely dispersed areas. We tested the hypothesis that the spindle cells in these multicentric lesions originate from a single clone of precursor cells. To determine whether Kaposi's sarcoma is a monoclonal disorder, we assessed the methylation patterns of the androgen-receptor gene (HUMARA) in multiple lesions from women with the acquired immunodeficiency syndrome. In polyclonal tissues, about half the copies of each HUMARA allele are methylated, whereas in cells derived from a single clone all the copies of only one allele are methylated. To minimize contamination by normal DNA, we used microdissection to isolate areas composed primarily of spindle cells, the putative tumor cells. Eight patients with a total of 32 tumors were studied. Of these tumors, 28 had highly unbalanced methylation patterns (i.e., predominant methylation of one HUMARA allele). In all the tumors that had unbalanced methylation from a given patient, the same allele predominated. These data indicate that Kaposi's sarcoma is a disseminated monoclonal cancer and that the changes that permit the clonal outgrowth of spindle cells occur before the disease spreads.

Systemic Hematologic Effects of PEG-rHuMGDF–Induced Megakaryocyte Hyperplasia in Mice

PEG-rHuMGDF injected daily in normal mice causes a rapid dose-dependent increase in megakaryocytes and platelets. At the same time that platelet numbers are increased, the mean platelet volume (MPV) and platelet distribution width (PDW) can be either decreased, normal, or increased depending on the dose and time after administration. Thus, PEG-rHuMGDF at a low dose causes decreases in MPV and PDW, MGDF at an intermediate dose causes an initial increase followed by a decrease in MPV and PDW, and PEG-rHuMGDF at higher doses causes an increase in MPV and PDW followed by a gradual normalization of these platelet indices. In addition to the expected thrombocytosis after 7 to 10 days of daily injection of high doses of PEG-rHuMGDF, a transient decrease in peripheral red blood cell numbers and hemoglobin is noted accompanied in the bone marrow by megakaryocytic hyperplasia, myeloid hyperplasia, erythroid and lymphoid hypoplasia, and deposition of a fine network of reticulin fibers. Splenomegaly, an increase in splenic megakaryocytes, and extramedullary hematopoiesis accompany the hematologic changes in the peripheral blood and marrow to complete a spectrum of pathologic features similar to those reported in patients with myelofibrosis and megakaryocyte hyperplasia. However, all the PEG-rHuMGDF-initiated hematopathology including the increase in marrow reticulin is completely and rapidly reversible upon the cessation of administration of PEG-rHuMGDF. Thus, transient hyperplastic proliferation of megakaryocytes does not cause irreversible tissue injury. Furthermore, PEG-rHuMGDF completely ameliorates carboplatin-induced thrombocytopenia at a low-dose that does not cause the hematopathology associated with myelofibrosis.

TTF-1 Regulates Lung Epithelial Morphogenesis

TTF-1 is a homeodomain transcriptional factor expressed in thyroid, lung, and parts of the brain.In vitro,TTF-1 can activate the promoter of thyroid- and pulmonary-specific genes. We postulated that TTF-1 not only is essential for the activation of tissue-specific genes, but also may directly participate in epithelial cell morphogenesis. To test this postulate, we used an antisense oligonucleotide inhibitory strategy in anin vitromodel of embryonic mouse lung branching morphogenesis. This strategy suppressedTTF-1translation and inhibited lung branching morphogenesis. The resulting abnormal phenotype was characterized by hyperplastic and unorganized proliferation of epithelial cells in the airways. The mesenchymal compartment of the lung appeared to be unaffected. These results demonstrate, for the first time, that the expression of a homeoprotein transcriptional regulator is necessary for lung epithelial morphogenesis.

Adrenal lesion in multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia (MEN) type 1 is accompanied by adrenal involvement, but characteristics and clinical handling of this lesion have been insufficiently explored. Patients with MEN 1 (n = 43) were monitored (mean, 6.3 years) with annual biochemical and radiologic adrenal evaluation. Adrenal specimens were examined by in situ RNA-RNA hybridization for expression of the MEN1 candidate gene phospholipase C beta 3 (PLC beta 3) and immunostaining for insulin-like growth factor-1 receptor. Altogether 17 patients (40%) displayed adrenal enlargement, which was limited to the adrenal cortex and showed signs of progression, marked atypia, and cancer development in three of them. Only the carcinoma exhibited adrenocortical hormone excess. PLC beta 3 was expressed in the hyperplastic and adenomatous proliferation but not the carcinoma. Pancreatic endocrine tumors with insulin-proinsulin excess were overrepresented in the patients with adrenocortical involvement, but significant insulin-like growth factor-1 receptor immunoreactivity was restricted to the carcinoma. The prevalent adrenocortical lesion associated with MEN 1 requires regular attention because of malignant potential. It was unrelated to loss of constitution heterozygosity for the MEN1 locus (11q13) and PLC beta 3 expression, except for the cortical carcinoma exhibiting allelic losses involving also the Wiedemann-Beckwith gene at 11p15. Mechanisms for mitogenic relationships between the pancreatic and adrenal lesions of MEN 1 demand further clarification.

Loss of heterozygosity in lobular carcinoma in situ of the breast

Aims-(1) To investigate whether loss of heterozygosity identified at various loci in invasive breast carcinoma or is present in lobular carcinoma in situ (LCIS). (2) To investigate whether LCIS is a monoclonal (neoplastic) or a polyclonal (hyperplastic) proliferation.Methods-Forty three cases of LCIS (30 with associated invasive carcinoma or in situ ductal carcinoma (DCIS) and 13 cases of pure LCIS) were investigated for loss of heterozygosity on chromosomes 16q, 17q, 17p, and 13q using a microdissection technique, polymorphic DNA markers, and the polymerase chain reaction (PCR).Results-Loss of heterozygosity was detected in both subgroups of LCIS at all the loci examined. There was no significant difference in the frequency of the loss between the group associated with invasive carcinoma and the pure LCIS group. The frequency of loss of heterozygosity ranged from 8% on 17p to 50% on 17q.Conclusions-Because of the nature of the technique employed, our findings show that LCIS is a monoclonal (neoplastic) proliferation rather than a hyperplastic proliferation. The incidence of loss of heterozygosity on 17p (D17S796) is lower than we have observed previously in DCIS, suggesting that LCIS and DCIS are different genetically as well as clinically and morphologically. The similar incidence of loss of heterozygosity on 16q and 17q, however, suggests that DCIS and LCIS may share a common pathway of evolution.

Clonal analysis of regenerative nodules in hepatitis C virus-induced liver cirrhosis

Background/Aims: Based on histological criteria, regenerative nodules in cirrhotic liver have been generally considered to result from hyperplastic proliferation of hepatocytes. Whether these nodules are hyperplastic or neoplastic has not been determined definitively. This study examined the issue by clonal analysis of each nodule. Methods: The method for clonal analysis was based on restriction fragment length polymorphism of the X chromosome-linked phosphoglycerokinase gene and on random inactivation of the gene by methylation. Results: Clonality of hepatocellular carcinoma (n = 7) and regenerative nodules (n = 76) induced by hepatitis C virus infection was analyzed. All carcinomas were monoclonal. Clonal analysis of regenerative nodules showed that 43% (33 of 76) were monoclonal in origin. Adjacent monoclonal nodules showed inactivation of the same allele of phosphoglycerokinase gene. Because the gene allele is inactivated at random, it is unlikely that each nodule happens to inactivate the same allele; it is more likely that monoclonal cell expansion is initiated before the nodule is established by septum formation. Conclusions: Monoclonal cell expansion is seen in a considerable number of regenerative nodules in cirrhotic liver. The results indicate that certain genetic changes, which are required for hepatocarcinogenesis, have already occurred in these nodules.

Promoting effects of mancozeb on pancreas of nitrosomethylurea-treated rats.

Rats were treated with a single i.p. injection of the carcinogen nitrosomethylurea (NMU, 50 mg/kg b.w.) at day three of age. The treatment induced hyperplastic and atypical acinar cell proliferation [focal acinar cell hyperplasia (FACH)]. In this investigation, NMU treated rats were fed AIN-76 diet containing mancozeb (MZ; 100 mg/kg diet), a polymeric complex of ethylene bis (dithiocarbamate) manganese with zinc salt, which is an agricultural fungicide. Group one was treated with NMU plus MZ (MZ-NMU), group 2 received NMU alone (NMU), group 3 was fed MZ and saline injected (MZ-SAL) and group 4 was the saline injected control (SAL). Rats were killed at week 24 of age. In MZ-NMU group pancreas there were FACH, dysplastic foci (DYF) and carcinomas in situ (CIS). FACH were larger, coalescent and may show areas of undifferentiated cells (focus within focus). DYF contain proliferative acinar and ductular structures with loss of polarity but no malignant traits. CIS had medullary appearance or consisted of irregularly shaped acini and ducts in stromal framework. Cell had scant cytoplasm and large hyperchromatic, pleomorphic nuclei. DYF and CIS were not seen in MZ group pancreas. The MZ-NMU group had increased mitotic index and greater number of apoptotic cells. There was no pathologic change in MZ-SAL group. Our data indicated that MZ did not cause pancreatic cell proliferation in normal rats whereas it had distinct promoting and progressor effects on NMU initiated pancreatic cells. Thus, a two-stage protocol of pancreatic carcinogenesis was achieved. It is suggested that the NMU protocol may be useful for testing promoter, progressor or inhibitory effect of chemical and physical agents on cell proliferation and transformation of rat pancreas.