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R Albrechtsen

Publications and source records attributed to R Albrechtsen.

At least 37 records · Page 2Linked to original sources
PubMed1995

Mouse tetranectin: cDNA sequence, tissue-specific expression, and chromosomal mapping.

Tetranectin is a plasminogen-binding tetrameric protein originally isolated from plasma. Expression of tetranectin appears ubiquitous, although particularly high expression is noted in the stroma of malignant tumors and during mineralization. To dissect the molecular basis of tetranectin gene regulation, mouse tetranectin cDNA was cloned from a 16-day-old mouse embryo library. Sequence analysis revealed a 992-bp cDNA with an open reading frame of 606 bp, which is identical in length to the human tetranectin cDNA. The deduced amino acid sequence showed high homology to the human cDNA with 76% identity and 87% similarity at the amino acid level. Sequence comparisons between mouse and human tetranectin and some C-type lectins confirmed a complete conservation in the position of six cysteines as well as numerous other amino acid residues, indicating an essential structure for potential function(s) of tetranectin. The sequence analysis revealed a difference in both sequence and size of the noncoding regions between mouse and human cDNAs. Northern analysis of the various tissues from mouse, rat, and cow showed the major transcript(s) to be approximately 1 kb, which is similar in size to that observed in human. Although additional minor bands of 1.5 and 3.3 kb were found in Northern blots, RT-PCR (reverse transcription polymerase chain reaction) analysis failed to provide evidence that these minor bands are products of the tetranectin gene. Finally, the genetic map location for this gene, Tna, was determined to be on distal mouse Chromosome (Chr) 9 by analysis of two sets of multilocus crosses.

Amino Acid Sequence↗
PubMed1995

Laminin beta 2 chain and adhalin deficiency in the skeletal muscle of Walker-Warburg syndrome (cerebro-ocular dysplasia-muscular dystrophy).

Muscular dystrophy may be caused by disturbances in a number of muscle proteins that appear to be part of a chain of interacting molecules that includes cytoskeletal, cell membrane, and basement membrane components. We found that the skeletal muscle cells in two cases of Walker-Warburg syndrome were severely deficient in the laminin beta 2 chain and in adhalin. The findings indicate that these two proteins are key molecules in the interactive protein complex conferring muscle stability and cell survival.

Abnormalities, Multiple↗
PubMed1994

Human beta 2 chain of laminin (formerly S chain): cDNA cloning, chromosomal localization, and expression in carcinomas.

Overlapping cDNA clones that encode the full-length human laminin beta 2 chain, formerly called the S chain, were isolated. The cDNA of 5680 nt contains a 5391-nt open reading frame encoding 1797 amino acids. At the amino terminus is a 32-amino-acid signal peptide that is followed by the mature beta 2 chain polypeptide of 1765 amino acids with a calculated molecular mass of 192,389 Da. The human beta 2 chain is predicted to have all of the seven structural domains typical of the beta chains of laminin, including the short cysteine-rich alpha region. The amino acid sequence of human beta 2 chain showed 86.1% sequence identity to the rat beta 2 chain, 50.0% to the human beta 1 chain, and 36.3% to the human beta 3 chain. The greatest sequence identity was in domains VI, V, and III. The sequence of a 24-amino-acid peptide fragment isolated from the beta 2 chain of laminin purified from human amniotic basement membrane matched the sequence predicted from the cDNA, confirming that the cDNA encodes human beta 2 laminin. The cDNA was used to assign the gene (LAMB2) to human chromosome 3p21 by in situ hybridization. It is not linked to genes for human laminin chains alpha 1, beta 1, and gamma 1 or other known laminin genes. Immunostaining showed that the beta 2 chain is localized to the smooth muscle basement membranes of the arteries, while the homologous beta 1 chain is confined to the subendothelial basement membranes. The beta 2 chain was found in the basement membranes of ovarian carcinomas but not colon carcinomas. These results indicate that the expression of the beta 2 chain gene is tightly regulated in normal human tissues and in disease.

Amino Acid Sequence↗
PubMed1994

A potential role for tetranectin in mineralization during osteogenesis.

Tetranectin is a protein shared by the blood and the extracellular matrix. Tetranectin is composed of four identical, noncovalently bound polypeptides each with a molecular mass of approximately 21 kD. There is some evidence that tetranectin may be involved in fibrinolysis and proteolysis during tissue remodeling, but its precise biological function is not known. Tetranectin is enriched in the cartilage of the shark, but the gene expression pattern in the mammalian skeletal system has not been determined. In the present study we have examined the expression pattern and putative function of tetranectin during osteogenesis. In the newborn mouse, strong tetranectin immunoreactivity was found in the newly formed woven bone around the cartilage anlage in the future bone marrow and along the periosteum forming the cortex. No tetranectin immunoreactivity was found in the proliferating and hypertrophic cartilage or in the surrounding skeletal muscle. Using an in vitro mineralizing system, we examined osteoblastic cells at different times during their growth and differentiation. Tetranectin mRNA appeared in the cultured osteoblastic cells in parallel with mineralization, in a pattern similar to that of bone sialoprotein, which is regarded as one of the late bone differentiation markers. To explore the putative biological role of tetranectin in osteogenesis we established stably transfected cell lines (PC12-tet) overexpressing recombinant tetranectin as evidenced by Northern and Western blot analysis and immunoprecipitation. Both control PC12 cells and PC12-tet cells injected into nude mice produced tumors containing bone material, as evidenced by von Kossa staining for calcium and immunostaining with bone sialoprotein and alkaline phosphatase antiserum. Nude mice tumors established from PC12-tet cells contained approximately fivefold more bone material than those produced by the untransfected PC12 cell line or by the PC12 cells transfected with the expression vector with no insert (Mann Whitney rank sum test, p < 0.01), supporting the notion that tetranectin may play an important direct and/or indirect role during osteogenesis. In conclusion, we have established a potential role for tetranectin as a bone matrix protein expressed in time and space coincident with mineralization in vivo and in vitro.

Animals↗
PubMed1994

Selective assembly of laminin variants by human carcinoma cells.

BACKGROUND: The laminins are heterotrimeric basement membrane glycoproteins. Eight subunits that can be assembled into laminins have been characterized and are known as: A, B1, B2, S, M, K, B2t, B1k laminin chains. Although many neoplastic cells secrete laminins and some of them even assemble basement membranes, the pattern of production of various laminin subunits remains to be explored. EXPERIMENTAL DESIGN: The expression of laminin was examined in several human carcinoma cells using a panel of specific cDNA probes as well as polyclonal and chain specific monoclonal antibodies. For this purpose a human laminin S chain 2 kb cDNA was isolated and characterized and used together with existing probes for laminin chains. RESULTS: All carcinoma cell lines had a high level of expression of three light chains (B1, S and B2) mRNA. In contrast, the heavy chains of laminin, A and M, were expressed in negligible amounts as detected by Northern blotting and PCR. The only exception was the HU-1 lung adenocarcinoma cell line which expressed significant quantities of laminin M chain mRNA and lower levels of laminin A chain mRNA. The presence in the HU-1 cells of translated polypeptides was demonstrated by immunofluorescence staining. The cells contained both B1 and S chain laminin in the cell layer, but preferentially secreted the B1 chain into the culture supernatant as shown by Western blotting. The 300 to 400 kDa M chain immunoreactive band was found in laminin secreted into the culture medium of HU-1 cells. Immunoprecipitation of biosynthetically labeled proteins showed that the M chain was synthesized as a complex with B chains. Little or no A chain laminin was detected in the culture medium supernatant. HU-1 cells also synthesized the newly described laminin variant, epiligrin which was secreted into the medium. Thus, the HU-1 cells secreted two laminin variants: M-B1-B12 laminin and epiligrin into the culture medium. Immunostaining of HU-1 nude mice tumors showed that tumor basement membranes contained M, B1, and B2 laminin and epiligrin immunoreactivity but apparently no S chain. CONCLUSIONS: All human carcinoma cell lines produced laminin chains B1, B2 and S, but no or little A or M. The only exception was the lung carcinoma cell line HU-1. Human HU-1 carcinoma cells in culture synthesize several homologous laminin chains and regulate the process of assembly, secretion and deposition of laminin variants into tumor basement membranes. These data indicate that the tumor cells vary among themselves with regards to laminin production and that some of them, like HU-1 may produce essentially all laminin chains simultaneously.

Amino Acid Sequence↗
PubMed1992

Carcinoma-associated perisinusoidal laminin may signal tumour cell metastasis to the liver.

The perisinusoidal space of the liver shows extensive modulation of the extracellular matrix in response to various pathological conditions. We studied perisinusoidal laminin expression immunohistochemically using polyclonal and monoclonal antibodies in 110 human liver specimens obtained at autopsy. In normal adult liver the perisinusoidal spaces contained only minimal amounts of immunoreactive laminin. In 86% of patients dying from cancer with liver metastasis, however, a distinct increase in the amount of perisinusoidal laminin could be demonstrated. The perisinusoidal space also contained laminin in cancer patients without liver metastasis. In 3 cases of leukaemia sinusoids were laminin negative. In cirrhosis and chronic passive congestion there was, as expected, laminin immunoreactivity in the perisinusoidal space. The results obtained using polyclonal antibodies against laminin were confirmed using chain-specific monoclonal antibodies against B2 laminin. In an ex vivo assay, viable tumour cells (Panc-1 and clone A) were found to bind with remarkable specificity to frozen sections of liver tissue containing perisinusoidal laminin as opposed to liver tissues without laminin. We suggest that this perisinusoidal laminin may directly on indirectly mediate tumour cell metastasis to the liver.

Carcinoma↗
PubMed1992

Tetranectin, a plasminogen kringle 4-binding protein. Cloning and gene expression pattern in human colon cancer.

BACKGROUND: Tetranectin is a recently discovered protein that binds to kringle 4 region of plasminogen (Clemmensen I, Petersen LC, Kluft C. Eur J Biochem 1986; 156:327. EXPERIMENTAL DESIGN: The mRNA encoding human tetranectin was cloned by using degenerate primers in a reverse transcriptase reaction followed by polymerase chain reaction amplification. The resulting polymerase chain reaction product was examined by DNA sequencing and subsequently used as probe for screening a human placental cDNA library. A full length cDNA clone (TET-1) was isolated, characterized, and used for Northern blot and in situ hybridization. RESULTS: DNA sequencing analysis revealed a 874-base pair cDNA containing an open reading frame of 606 base pairs encoding 202 amino acids. A classical signal peptide was present starting with the initiation methionine. The mature tetranectin chain consisted of 181 amino acids (M(r) = 20,169). The 3' noncoding region contained a single polyadenylation signal and a 26-residue poly A tail. The predicted amino acid sequence of the mature tetranectin chain showed, except for one amino acid, complete identity to that obtained by sequencing of the native protein (Fuhlendorff J, Clemmensen I, Magnusson S, Biochemistry 1987;26:6757). Northern blot of poly A+ revealed a single band of approximately 1 kb. Northern blot analysis of poly A+ isolated from a series of normal human tissues (lung, liver, spleen, kidney, and pancreas) revealed a distinct hybridization band that was especially prominent in the lungs and spleen. No hybridization signal was detected in three carcinoma cell lines examined in parallel. Northern blot analysis of poly A+ RNA isolated from solid tumors revealed a tetranectin specific mRNA band. In situ hybridizations on tissue sections of colon carcinomas and normal colon tissues revealed a strong and distinct hybridization signal of stromal cells in colon carcinomas but not in tumor cells. Only a few stromal cells were labeled in the normal colon. Immunohistochemically, tetranectin was found in a fibrillar-like pattern in the extracellular matrix around the tumor islands and was not detectable in the normal colon stromal tissue. Plasminogen exhibited a similar immunohistochemical staining pattern as tetranectin. CONCLUSIONS: Human tetranectin cDNA comprises 874 base pairs including a 606-base pair open reading frame encoding 202 amino acids including a classical signal peptide. This protein is produced locally by cells of the stromal compartment of tumors and is deposited into the extracellular matrix. Since tetranectin binds to plasminogen we hypothesize that it could function as an anchor and/or reservoir for plasminogen and similar substances that regulate tumor invasion and metastasis as well as tumor angiogenesis.

Amino Acid Sequence↗
PubMed1992

Laminin A, B1, B2, S and M subunits in the postnatal rat liver development and after partial hepatectomy.

The expression of laminin subunits (A, B1, B2, S and M) in the perisinusoidal space of the rat liver was studied in early postnatal life, in the adult, and after partial hepatectomy. In the perisinusoidal space of the normal adult rat, laminin was detected with polyclonal antibodies only in small streaks of basement membranes extending from the portobiliary tract and to a lesser degree from the central vein. Occasionally, droplets of laminin immunoreactivity were also found along the intervening portions of the perisinusoidal spaces. All morphologically identifiable basement membranes of the rat liver (biliary ducts and blood vessels) irrespective of the age of animals exhibited B1, B2 and S immunoreactivity. Laminin A was restricted to the larger blood vessels and could not be detected in the biliary ducts. In the adult rat, immunoreactivity for the A-like M subunit was absent except for some negligible immunostaining of the blood vessels. In the neonatal rat strong linear laminin immunoreactivity was present in the perisinusoidal spaces throughout the entire lobule. Structurally, this laminin is not organized into a basement membrane as defined by electron microscopy. The perisinusoidal laminin was reactive with antibodies to B1, B2, S and M but the A subunit was absent. Sequential immunohistochemical studies of progressively older animals revealed that B1, B2, S and M immunoreactivity was weak in the perisinusoidal spaces before birth but during the postnatal life distinct linear immunoreactivities appeared. Most intense immunoreactivity was present at 1 to 2 weeks after birth. The perisinusoidal laminin gradually disappeared in growing animals and by 6 to 8 weeks basically no laminin could be detected in this location. By Northern blot analysis increased levels of B1 and B2 were detected in neonatal rats as compared to adult rats. S-laminin mRNA could readily be demonstrated in neonatal rat livers by Northern blot analysis, whereas A and M could not. Expression of S and M-laminin transcripts were demonstrated by polymerase chain reaction, but we were unable to obtain a laminin A product. After partial hepatectomy a transient laminin immunoreactivity, comparable to that in the neonatal rats, was detected in the perisinusoidal spaces. Laminin was most prominent 3 days after resection and reacted with antibodies to B1, B2, S and M. No A subunit could be detected in this extracellular matrix.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1990

Deoxyribonucleic-binding homeobox proteins are augmented in human cancer.

Homeobox genes encode sequence-specific DNA-binding proteins that are involved in the regulation of gene expression during embryonic development. In this study, we examined the expression of homeobox proteins in human cancer. Antiserum was obtained against a synthetic peptide derived from the highly conserved 60 amino acid homeodomain. This peptide antiserum recognized a protein species of molecular weight 63,000 in immunoblots of nuclear extracts obtained from several tumor cell lines. The predominant molecular weight 63,000 nuclear protein recognized by the peptide antiserum was then isolated and used to elicit a rabbit antiserum. In immunostaining, both antisera reacted with the nuclei of cultured tumor cells. In tissue sections of human carcinoma, nuclear immunoreactivity was observed in the tumor cells in 40 of 42 cases examined. Adjacent normal epithelial tissue obtained from the same patients exhibited little immunoreactivity. Both the peptide antiserum and the polyclonal antiserum against the native protein immunoblotted a molecular weight 63,000 protein in nuclear extracts of tumor tissue, but not significantly in extracts of normal tissue. At the molecular level, the presence of the homeobox transcript in human carcinoma was documented by in situ hybridization and RNase protection mapping. These results demonstrate that human cancer is associated with the expression of homeobox proteins. Such homeobox proteins, as well as other regulatory proteins, could be involved in the initiation or maintenance of the malignant phenotype.

Animals↗
PubMed1988

Heterogeneity of secretory granules of silent pituitary adenomas.

Silent pituitary adenomas were compared with hormonally active tumors taking into account the size, number, and ultrastructural characteristics of secretory granules (SG). The study group (a total of 79 primary pituitary adenomas) comprised 27 silent, 21 growth hormone (GH)-producing-, 16 prolactin (PRL)-producing-, 5 GH-PRL-producing- and 10 adrenocorticotropic hormone (ACTH)-producing adenomas. The SG of silent adenomas were significantly smaller than SG in endocrine active adenomas. All hormonally inactive tumors also contained small (mean, 94 nm) specific cytoplasmic granules, designated "silent adenoma granules" (SIG). The fine structural features of the SIG included: a flocculent, granular material occupying an eccentric position in a larger vesicle limited by a double membrane. In the silent adenomas this particular granule was present in up to 90% of the adenoma cells and constituted approximately 10 to 50% of the granules in each cell. These granules were not seen in hormonally active tumors and considered therefore diagnostic of silent pituitary adenomas.

Adenoma↗
PubMed1988

Osteonectin/SPARC/BM-40 in human decidua and carcinoma, tissues characterized by de novo formation of basement membrane.

The identification and cDNA cloning of bone-enriched osteonectin and parietal endoderm-enriched SPARC indicated that these proteins share greater than 90% homology. The present study reports substantial expression of this Mr 43,000 protein in human decidua and carcinoma. Metabolic labeling of human decidua tissue in organ culture demonstrated significant osteonectin biosynthesis. Further, Northern analysis and in situ hybridization showed that the osteonectin mRNA level in human decidua is very high. Immunohistochemically, the large mature decidual cells exhibited faint cytoplasmic immunoreactivity with antibodies to osteonectin and a distinct immunoreactivity of the newly deposited basement membranes encircling these cells. The intermediate-sized decidual cells exhibited a strong cytoplasmic immunostaining with antibodies to osteonectin. The small elongated stromal cells were devoid of osteonectin immunoreactivity. Blood vessels exhibited variable positive immunoreactivity. The osteonectin expression in 38 cases of human carcinomas was examined. In well-differentiated carcinomas osteonectin immunoreactivity was located in the basement membrane area, codistributing with laminin. Cytoplasmic osteonectin immunoreactivity was found in poorly differentiated carcinomas. Stromal cells in the peritumoral tissue and some vessels were immunoreactive. Using in situ hybridization, it appeared that both the tumor cells and the stromal cells contained osteonectin transcripts. In normal steady state human nonosseus tissues investigated, osteonectin was found inconsistently in the basement membranes only, as based on the present immunohistochemical technique. These results suggest that the osteonectin/SPARC gene appears activated in certain human tissues characterized by de novo formation of basement membrane.

Animals↗
PubMed1987

Role of laminin receptor in tumor cell migration.

Polyclonal antisera were made against biochemically purified laminin receptor protein as well as against synthetic peptides deduced from a complementary DNA clone corresponding to the COOH-terminal end of the laminin receptor (U.M. Wewer et al., Proc. Natl. Acad. Sci. USA, 83: 7137-7141, 1986). These antisera were used to study the potential role of laminin receptor in laminin-mediated attachment and haptotactic migration of human A2058 melanoma cells. The anti-laminin receptor antisera reacted with the surface of suspended, nonpermeabilized melanoma and carcinoma cells. The anti-laminin receptor antisera blocked the surface interaction of A2058 cells with endogenous laminin, resulting in the inhibition of laminin-mediated cell attachment. The A2058 melanoma cells migrated toward a gradient of solid phase laminin or fibronectin (haptotaxis). Anti-laminin antiserum abolished haptotaxis on laminin but not on fibronectin. Synthetic peptide GRGDS corresponding to the fibronectin cell-binding domain inhibited haptotaxis on fibronectin but not on laminin. Both types of anti-laminin receptor antisera inhibited haptotaxis on laminin but not on fibronectin. Using immunohistochemistry, invading human carcinoma cells in vivo exhibited a marked cytoplasmic immunoreactivity for the receptor antigen. Together these findings indicate a specific role for the laminin receptor in laminin-mediated migration and that the ligand binding of the laminin receptor is encompassed in the COOH-terminal end of the protein.

Cell Adhesion↗
PubMed1987

Light bodies in human pituitary adenomas.

Light bodies are large cytoplasmic granules originally described in the gonadotrophic cells of the rat pituitary gland. In order to determine whether similar bodies occur in the human anterior pituitary gland, 89 pituitary adenomas and periadenomatous tissue from 20 cases were examined by transmission electron microscopy. Double membrane bound bodies with filamentous internal structure identical to rodent light bodies were identified in 10 hormone-producing adenomas: 5 PRL, 1 PRL-GH, 2 GH, and 2 ACTH-producing tumours. No light bodies were found in the remaining 79 tumours nor in the pituitary cells in periadenomatous tissue from 20 cases. These results show that some human pituitary adenomas may contain light bodies identical to those seen in gonadotrophs of rat pituitary.

Adenoma↗
PubMed1987

Laminin in the anterior pituitary gland of the rat. Laminin in the gonadotrophic cells correlates with their functional state.

The distribution pattern of laminin in the rat anterior pituitary gland under physiological and hormonally altered conditions was studied immunohistochemically. Intense immunoreactivity of the capillaries and of the basement membranes surrounding parenchymal cells was found. Five to 10% of the parenchymal cells of normal adult rat pituitary gland exhibited also intense positive cytoplasmic staining. These were identified as gonadotrophic cells on the basis of their topographic distribution and typical 700-nm light bodies. By immunoelectron microscopy it was shown that the light bodies contain laminin and tubulin. After treatment with estrogen, which is known to suppress the function of the gonadotrophic cells, virtually no cytoplasmic laminin was found. Ultrastructurally, the number of light bodies in the gonadotrophic cells diminished significantly, from approximately 3 to 8 per cell to 0 to 1 per cell in a given section. In contrast, after castration, the number of laminin positive cells increased to a number above that found in the normal adult male rat, and the number of light bodies increased two to four times. Based on these results, it appears that the presence of cytoplasmic laminin and the number of light bodies reflects the hormonal activity of the gonadotrophic cells of the rat pituitary gland.

Animals↗
PubMed1986

Intercellular deposits of basement membrane material in active human pituitary adenomas detected by immunostaining for laminin and electron microscopy.

Thirty-eight human pituitary adenomas (24 endocrine active and 14 endocrine inactive tumors) were studied immunohistochemically for the presence of the basement membrane component, laminin, and ultrastructurally for the presence of basement membrane. Immunoreactivity of laminin delineated staining of epithelial and endothelial basement membranes, the reaction product being confined mostly to the perivascular zones. Moreover, a hitherto undescribed presence of intercellular laminin-positive droplets was observed in ten of the active adenomas (nine patients with hyperprolactinemia and/or acromegalia and one patient with Cushing's syndrome). Concurrently, at the ultrastructural level, bunches of basement membrane-like material intermingled between the adenoma cells were demonstrated in seven of these ten active adenomas. Furthermore, secretory granules were entrapped occasionally in this intercellular matrix, indicating a mutual dependence between excessive hormone extrusion and an increase of "misplaced" deposits of basement membrane components, e.g., laminin.

Adenoma↗
PubMed1986

Altered levels of laminin receptor mRNA in various human carcinoma cells that have different abilities to bind laminin.

The human laminin receptor was purified and molecularly cloned to investigate its biosynthetic regulation. Laminin receptor from normal and neoplastic tissue was preparatively affinity purified to homogeneity based on the high affinity of the receptor for laminin. The apparent molecular weight of the receptor from different carcinoma sources and from normal placental tissue is in the range of 68-72 kDa. Isoelectric focusing and two-dimensional gel electrophoresis indicated that the receptor protein consists of one major polypeptide chain with a pI value of 6.4 +/- 0.2. Laminin receptor cDNA clones were isolated after screening a human endothelial lambda gt11 cDNA library with a monoclonal antibody directed against a domain of the laminin receptor involved in ligand binding. Definitive identification of the cDNA clones was based on comparison of cDNA sequence with the amino acid sequence of a cyanogen bromide-generated octapeptide of purified placental laminin receptor. The laminin receptor mRNA is approximately 1700 bases long. The level of laminin receptor mRNA in a variety of human carcinoma-derived cell lines correlated with the number of laminin receptors on the cell surfaces of those cells. This suggests that the amount of laminin receptor mRNA may be a rate-limiting control step in the biosynthesis of the laminin receptor, and hence in the regulation of cellular attachment to basement membranes via laminin.

Amino Acid Sequence↗
PubMed1986

Laminin production by human endometrial stromal cells relates to the cyclic and pathologic state of the endometrium.

The cyclic changes in the presence of the basement membrane glycoprotein laminin in endometrial stromal cells was studied by immunohistochemistry. The interstitial matrix around the stromal cells of the proliferative phase of the normal menstrual cycle was unreactive with antibodies to laminin. However, commencing with the secretory phase, stromal cells accumulated distinct cytoplasmic and pericellular laminin-immunoreactive material. The maximal amount of stromal cell-associated laminin was observed in predecidual cells of the late secretory phase. Thus, laminin immunostaining discriminates stromal cells of the proliferative phase (being "negative") from those in the secretory phase (being "positive"). Sixty-six cases of endometrial hyperplasia and adenocarcinomas were also stained with antibodies to laminin. Sixty-nine percent of biopsies of cystic hyperplasia and 30% of adenomatous hyperplasia contained laminin-positive stromal cells. Ultrastructural examination of stromal cells in cystic hyperplasia revealed the presence of pericellular basement membrane-like material, focally arranged into typical lamina rara and lamina densa. In contrast, stromal cells in the atypical adenomatous hyperplasia and adenocarcinomas did not react with antibody to laminin. The expression of laminin receptor in the stromal cells codistributed with laminin. Basement membranes of the surface epithelium, the glandular epithelium, and the vessels stained strongly with antibodies to laminin. In preneoplastic and neoplastic tissues, laminin immunostaining revealed discontinuous and defective basement membranes. In poorly differentiated carcinomas only sparse amounts of laminin-positive basement membrane were observed; these tumors, in contrast, exhibited cytoplasmic laminin and also significant immunoreaction with antibodies to laminin receptor.

Basement Membrane↗