Expression of CD44 and variant isoforms in cervical intraepithelial neoplasia

The cell adhesion molecule CD44 and its variant isoforms have been found to be related to invasive and metastatic character of cancer cells. Their expression in gynecologic precancerous lesions has not yet been reported. Mouse monoclonal antibodies directed against a common epitope (CD44s) and exons 4v, 6v, and 9v were used to study the expression of CD44 and variant isoforms by immunohistochemistry in cervical intraepithelial neoplasia (CIN). Twenty tissue samples with normal cervical epithelium and 57 samples with CIN of different histological grades and different HPV status were included in this study. The standard CD44, CD44-4v, CD44-6v, and CD44-9v were expressed in normal cervical epithelium and in precancerous lesions. In distinct contrast to the normal epithelium, however, the standard CD44, CD44-4v, and 6v showed a reduced expression in precancerous lesions, whereas CD44-9v was significantly overexpressed. Expression of CD44 standard and CD44-4v was correlated with the histological grade but not with the HPV status. Compared with mild and moderate dysplasia, severe dysplasia and carcinoma in situ are associated with low expression of CD44s (P = 0.007) and of CD44-4v (P = 0.03). These observations reveal dynamic changes in CD44 expression during neoplastic cell transformation in cervical intraepithelial neoplasia.     

Expression of CD44 variant isoforms in peripheral blood leukocytes in malignant lymphoma and leukemia: inverse correlation between expression and tumor progression

In a variety of human tumors, including high grade Non-Hodgkin's lymphoma (hgNHL), a linkage between expression of CD44 variant isoforms (CD44v) and tumor progression has been described. In search of an easily accessible diagnostic parameter, expression of CD44 standard (CD44s) and CD44 variant isoforms (exons v5, v6, v7 and v10) in peripheral blood lymphocytes (PBLs) of patients with hematological malignancies was evaluated by fluorescence activated cell scanning. The analysis of 30 blood samples of healthy donors and patients with non-malignant diseases and of 183 blood samples of patients with malignant hematological disorders revealed that only in patients with malignant disorders did a measurable proportion of PBLs express CD44 variant isoforms, mostly exons v5, v6, v7 and, less frequently, exon v10. Elevated levels of CD44v expression were noted in PBLs of patients with acute and chronic myeloid leukemia (AML: 16%, CML: 25%), Hodgkin's disease (HD: 17%), multiple myeloma (MM: 22%), polycythemia vera (PV: 33%), acute lymphoid leukemia (ALL: 23%) and, most frequently, in PBLs of patients with non-Hodgkin's lymphoma (NHL:54%). CD44v expression was not restricted to the malignant phenotype, but instead was also noted in T cells, B cells and monocytes, preferentially in a subpopulation of large cells. Furthermore, expression of CD44v in PBLs was not linked to the histological grading or clinical staging. There was, however, an inverse correlation with tumor progression, whereas response to therapy was frequently accompanied by upregulation of CD44v. Thus, expression of CD44v in the PBLs of patients with NHL mainly reflected immune responsiveness. Since NHL manifests itself primarily in lymphoid organs, its progression is difficult to follow. Monitoring of CD44v in PBLs could be used as an additional and convenient parameter for surveying the course of disease.     

Expression of CD44 standard and CD44 variant 6 in human lung cancer

We immunohistochemically examined the expression of CD44 standard (CD44 st) and CD44 variant 6 (CD44 v6) in 112 cases of primary lung cancer, and their relationship to the clinical milieu, including the clinical stage. In 46 cases of squamous cell carcinoma, expression of CD44 st was observed in 45.7% of the cases, and expression of CD44 v6 was observed in 60.9%. In 43 cases of adenocarcinoma, positive staining of CD44 st and CD44 v6 was seen in 2.3% and 4.7% of the cases, respectively. None of 21 small cell carcinomas was positive for CD44 st or CD44 v6. In squamous cell carcinomas, the expression of CD44 st and CD44 v6 was observed at a rate significantly higher than in other histologic type. Most specimens positive for CD44 st stained positively for CD44 v6. Therefore, it seems likely that the CD44 expression observed in squamous cell carcinoma of the lung was a variant CD44 containing the domain encoded by variant exon 6. The expression of CD44 v6 was not related to the clinical stage. Significant association between CD44 v6 and differentiation of squamous cell carcinoma was seen; 2/7 (28.6%) for poorly differentiated, 19/31 (61.3%) for moderately differentiated, and 7/8 (87.5%) for well differentiated squamous cell carcinomas (p = 0.02 by trend test). It was previously reported that CD44 st and CD44 v6 were expressed in both normal bronchial epithelium and squamous cell metaplasia. These results suggest that the expression of CD44 v6 in squamous cell carcinoma of the lung may reflect the immunohistochemical characteristics of the tissue from which such carcinoma emerge.     

Structural variability of CD44v molecules and reliability of immunodetection of CD44 isoforms using mAbs specific for CD44 variant exon products

CD44 can be considered structurally and functionally one of the most variable surface molecules. Alternative splicing of variant exons as well as posttranslational modifications of the molecule (differences in glycosylation) generate a rich repertoire of CD44 isoforms (CD44v), some of which seem to play a key role in tumor growth and progression. Immunodetection of CD44 isoforms in vivo, using mAbs specific for CD44 variant exon products, is largely used to identify those CD44 molecules involved in tumor growth and progression and to interfere with CD44-mediated processes. In the present work we demonstrate that the immunoreactivity of some mAbs directed to CD44 exon-specific epitopes can be impaired by the structural variability of the molecule. Our findings demonstrate that (1) specific exon assortment and/or posttranslational modifications of CD44v molecules can mask CD44 exon-specific epitopes; (2) glycosaminoglycan side chains, carried by some CD44v isoforms of high molecular weight, may play a critical role in determining the exact conformation of the molecule, which is necessary for the detection of CD44 variant epitopes by specific mAbs; and (3) in a panel of stable transfectants expressing CD44 N-glycosylation site-specific mutants, generated in the constant region of CD44 extracellular domain, asparagine-isoleucine substitution is sufficient per se to impair the immunoreactivity of several mAbs to pan-CD44. Thus, conformational changes due to the alternative splicing of CD44 variant exons and/or posttranslational modifications of the molecule (different degree of glycosylation), which are cell type-specific, are likely to generate CD44 variants that elude immunodetection. These findings strongly suggest that immunohistochemical analysis of CD44 expression in vitro and in vivo, using mAbs specific for CD44 variant exon epitopes, can potentially be impaired by a large number of false negative results.     

Expression of CD44 variant exons by primary and metastatic oral squamous carcinomas

Abnormal CD44 expression in many neoplasms correlates with behaviour, but reports on its role in oral squamous carcinoma are contradictory. CD44 expression was characterised in a closely matched series of oral carcinomas with and without metastases in both frozen and formalin-fixed tissue and correlated with behaviour and histological grading parameters. Eleven primary oral squamous carcinomas without metastases and nine primary carcinomas with 19 matched metastases were stained immunocytochemically for CD44H and products of variant exons v3, v4/5, v6 and v9. Patterns of staining in frozen and formalin-fixed tissue were correlated with invasive front grading and behaviour using exact inferential statistics. Most primary carcinomas stained for all exons tested but some showed loss of expression of v4/5. Loss of expression was more marked in metastases, but there was no correlation between expression and behaviour or grade. Stromal surfaces of epithelial cells often expressed variant exon products reflecting loss of polarity. This, together with selective loss of v4 and v5 in primary carcinomas and their more frequent loss in metastases, suggests that CD44 may play a role in metastasis of some oral squamous carcinomas.     

Expression of E-cadherin, alpha-catenin, beta-catenin, and CD44 (standard and variant isoforms) in human cholangiocarcinoma: an immunohistochemical study

Immunolocalization of E-cadherin (E-cad), alpha-catenin, beta-catenin, and CD44 has rarely been investigated in human cholangiocarcinoma (CC). We, therefore, immunohistochemically examined the expression of E-cad, alpha-catenin, beta-catenin, CD44 standard (CD44s), and CD44 variants (CD44v) including CD44v5, CD44v6, CD44v7-8, and CD44v10 in normal adult livers and in 47 cases of CC; and the results were then correlated with tumor grade, vascular invasion, metastasis, p53 expression, proliferative fraction (Ki-67 labeling), and c-erbB2 expression. In normal livers, E-cad, alpha-catenin and beta-catenin, but not CD44s, CD44v5, CD44v6, CD44v7-8, and CD44v10, were expressed at the cell membrane of normal intrahepatic bile ducts. In CC, membranous expression of E-cad, alpha-catenin, and beta-catenin was the same or reduced when compared with non-cancerous bile ducts in the majority of CC. We found that the down-regulation of E-cad, alpha-catenin, and beta-catenin expression significantly correlated with tumor high grade, but not with vascular invasion, metastasis, p53 expression, Ki-67 labeling, or c-erbB2 expression, except for beta-catenin, the down-regulation of which was associated with c-erbB2 down-regulation. CD44s, CD44v5, CD44v6, CD44v7-8 and CD44v10 were frequently expressed at the membrane of CC cells. There were, however, no significant correlations between these aberrant CD44 expression and tumor grade, metastasis, vascular invasion, p53 expression, Ki-67 labeling, or c-erbB2 expression, with a few exceptions of CD44s and CD44v5. We found that CD44s aberrant expression significantly correlated with absence of metastasis and vascular invasion, and that CD44v5 aberrant expression significantly correlated with p53 under-expression. These results suggest that membranous expression of E-cad, alpha-catenin, and beta-catenin is reduced in a majority of CC and this down-regulation correlates with CC high grade, and that beta-catenin down-regulation is associated with c-erbB2 down-regulation. The data also suggested that CD44s, CD44v5, CD44v6, CD44v7-8, and CD44v10 may be neoexpressed during carcinogenesis of CC but this neoexpression does not correlate with tumor progression in CC, with the exception of CD44s and CD44v5.     

Regulation of CD44v6-containing isoforms during proliferation of normal and malignant epithelial cells

CD44 is a family of molecules involved in cell-cell and cell-matrix interactions. Various isoforms of CD44 arise by insertion of one or more of the variant exons into the common backbone shared by all forms of CD44. In this work, we studied the expression of CD44 and exon v6-containing CD44 isoforms (CD44v6) in several nonmalignant and malignant conditions and the possibilities for regulating the expression of CD44v6. In primary squamocellular carcinomas of the head and neck, CD44 and CD44v6 were down-regulated in poorly differentiated tumors, whereas these molecules were uniformly expressed in the normal squamocellular epithelium, in proliferating skin diseases, and in nonmalignant tumors. When CD44v6 expression of original tumors and that of squamocellular carcinoma cell lines derived from them were compared, no CD44v6 up-regulation could be observed on in vitro growing cells. Moreover, several regulators were unable to up-regulate CD44v6 expression on cultured cell lines in vitro. When the same cell lines formed tumors after s.c. injection into severe combined immunodeficient mice, some of them up-regulated their CD44v6 expression. These data suggest that cell lines at certain differentiation stages can be induced to express CD44v6. Our results further indicate that CD44v6 positivity cannot be used as a universal indicator of tumor metastasis. Instead, the down-regulation of CD44v6 in squamocellular tumors is a sign of malignant transformation of the epithelium.     

Cytosol concentrations of CD44 isoforms in breast cancer tissue

Skeins or skein-like inclusions (SLIs) in motor neurons detected by ubiquitin immunohistochemistry are a characteristic finding of amyotrophic lateral sclerosis (ALS). Here we report ubiquitinated SLIs in the putamen and caudate nucleus from a case of ALS with dementia. A 48-year-old Japanese man developed apathy and amimia. Mental and neurological examinations revealed severe character change, muscle atrophy and fasciculation of the distal upper extremities and the tongue, and an exaggeration of the deep tendon reflex. He subsequently showed dysphagia and dysarthria. He died at the age of 51 years, after a total clinical course of about 2.5 years. By immunohistochemistry, ubiquitin-immunoreactive intraneuronal inclusions were observed in the spinal anterior horn cells, the frontal, temporal and entorhinal cortices, dentate fascia of the hippocampus and the amygdala. In addition, ubiquitinated inclusions were also seen in the putamen and caudate nucleus, which appeared as aggregates of thread-like structures similar to SLIs in the spinal anterior horn neurons. They were not seen on hematoxylin-eosin staining, and they also did not show any argentophilia nor did they react with other antibodies, including antibody against tau protein. To our knowledge, this is the first report of the presence of SLIs in non-motor neurons. Our results thus support the notion that ALS is a multisystem disease, and not simply a disease of the motor neurons.     

Expression of CD44 containing variant exon 9 (CD44v9) in gastric adenomas and adenocarcinomas: relation to the proliferation and progression

The expression of CD44 splice variant containing exon 14 (variant exon 9: CD44v9) was examined immunohistochemically in non-neoplastic mucosa, adenoma and adenocarcinoma of the stomach and analyzed the relation with the expression of Ki-67 antigen and p53 protein. In non-neoplastic gastric mucosa, basolateral membrane of the epithelial cells in the pyloric glands showed the expression of CD44v9. The epithelial cells in the intestinal metaplastic mucosa of the stomach sometimes expressed CD44v9. In the neoplastic lesions, the expression of CD44v9 was detected in 20% (34/170) of the adenomas and 28% (132/478) of the adenocarcinomas, respectively. The incidence of CD44v9 expression did not differ among histological type of gastric carcinoma. Twelve per cent of the adenocarcinomas showed strong expression of CD44v9, whereas non of the adenomas did. The incidence of CD44v9 expression was significantly higher in carcinomas invading into muscularis propria or the cases of stages 3 and 4 in comparison with that in carcinomas limited to submucosa or the stages 1 and 2 cases (p<0.05). The incidence of positive cases was higher in carcinomas with lymph node metastasis than those without metastasis (p<0.05). The expression of CD44v9 was significantly correlated with the expression of Ki-67 (p<0.05). It was also correlated with the expression of p53 protein in the tumor cells (p<0.01). These findings overall suggest that the expression of CD44v9 may be associated with the development as well as progression of the gastric carcinomas.     

Expression of antisense CD44 variant 6 inhibits colorectal tumor metastasis and tumor growth in a wound environment

Up-regulation of CD44 variant isoforms has been linked to the progression of epithelial tumors and the metastatic phenotype. Here we report a functional role for CD44 variant isoforms in colorectal cancer metastasis. An antisense mRNA approach was used to down-regulate CD44 variant isoforms containing CD44 variant 6 (v6) in the metastatic colorectal tumor cell line HT29. Cell lines stably expressing antisense CD44 exon 10 (v6) showed reduced expression of alternatively spliced CD44 variant isoforms but no significant change in expression of CD44 core protein, as judged by immunohistochemical analysis using CD44 domain-specific monoclonal antibodies. Expression of antisense exon 10 (v6) had no effect on HT29 tumor cell proliferation in vitro or the ability of the cells to bind immobilized hyaluronan, but it resulted in a reduced capacity to form liver metastases in nude mice following intrasplenic injection. Metastases were not detected in nude mice inoculated with antisense CD44 exon 10 (v6)-expressing cell lines after 4 months, against a background of a 30% metastasis rate in the control HT29 parental and vector alone transfected lines. Furthermore, whereas 82% of mice intrasplenically injected with control HT29 parental and vector alone cell lines developed tumors in incisional wound sites, none of the mice injected with antisense exon 10 expressing HT29 cells developed similar tumors. This is the first demonstration that antisense RNA can be used to selectively inhibit expression of specific domains of a molecule generated through alternative mRNA splicing while allowing expression of core domains to remain unaffected. Furthermore, these results provide direct evidence for a functional role of CD44 variant isoforms in the metastasis of human colorectal tumor cells and may suggest a critical role for CD44 variants in promoting cell growth specifically in the cytokine/growth factor-enriched environment of a wound site.     

Expression of CD44 variant 6 and lymphatic invasion: importance to lymph node metastasis in gastric cancer

Lymph node metastasis is a critical prognostic factor for gastric cancer. In the present investigation we examined clinicopathologic factors influencing the metastatic processes to the lymph mode and their prognostic importance. A randomly selected group of 98 patients with adenocarcinomas of the stomach who underwent gastrectomy plus systematic lymph node dissection at Osaka Police Hospital from 1991 to 1996 were analyzed. Altogether 37 (38%) cancers were positive for CD44 variant 6 (v6) staining, 31 (32%) were intermediately stained, and 30 (30%) were negative. CD44-v6 expression correlated well with lymph node metastasis. Expression of CD44-v6 and lymphatic invasion were independent risk factors for metastatic lymph nodes. Among the patients with CD44-v6-positive and lymphatic invasion-positive cancers, 88% had lymph node metastasis, whereas only 13% of patients negative for both factors had lymph node metastasis. Although CD44-v6 expression and lymphatic invasion have been reported to be risk factors for recurrence and a poor prognosis, in this investigation these factors were found not to be significant for hematogenous and lymphatic recurrences or overall survival rates. Thus expression of CD44-v6 and lymphatic invasion may regulate lymph node metastases from gastric cancer.     

Expression of fibrogenic cytokines in desmoplastic malignant melanoma

OBJECTIVE: Research has confirmed substantial links between OCD and AN. Not only are there psychopathological similarities between the two syndromes, but a marked neurochemical correspondence. Extensive exercising is a common feature of AN and also has relevance in its links with OCD. There is evidence from the exercise-induced weight-loss syndrome in animals that exercise and caloric restriction, in combination, tend to increase serotonergic activity in a synergistic manner. This syndrome has been proposed as a valid model of OCD as well as for AN. To date, little research has directly tested this theory in the human condition. METHOD: Fifty-three AN patients were categorized as high-level exercisers (N = 22) or moderate/nonexercisers (N = 31) based on the frequency of their physical activity over the year before assessment. RESULTS: Exercisers scored significantly higher on a measure of OC personality characteristics, OC symptomatology, and perfectionism--a personality factor associated with the development of Obsessive-Compulsive Personality Disorder. On the other hand, there were no group differences on other salient eating disorder characteristics such as body esteem, self-esteem, or weight preoccupation. There were also no differences in degree of emaciation as indicated by Body Mass Index. CONCLUSIONS: Findings suggest that among AN patients obsessional personality characteristics are linked to high-level exercising, and that exercising is associated with a greater degree of OC symptomatology. Results are discussed in the context of current theories of AN, OCD, and some biological mechanisms.     

Expression of apoptosis regulators in cutaneous malignant melanoma

Metastatic malignant melanoma (MM) is usually incurable and responds poorly to chemotherapy. Because many cytotoxic drugs cause cell death by inducing apoptosis, an imbalance of apoptosis regulatory proteins may contribute to MM treatment resistance. We have previously shown reduced expression of Bcl-2 protein, a negative regulator of apoptosis, in MM as compared with benign nevi. It is hypothesized that other apoptosis regulators may be involved in survival of MM cells. We examined the expression of Bax, Bcl-2, Bcl-X, and Mcl-1 in human benign nevi, primary MM, and metastatic MM using immunohistochemistry. Results were confirmed with Western blotting. The proapoptotic protein, Bax, was surprisingly overexpressed in all MM samples compared with benign nevi. Interestingly, in most MM samples there was overexpression of Mcl-1 or Bcl-XL, both negative regulators of apoptosis. Increased expression of Mcl-1 and Bcl-XL was first observed in thin primary melanomas, suggesting that up-regulation of these proteins represents a relatively early event associated with malignant transformation in MM. As published previously, the majority of primary and metastatic MM exhibited reduced Bcl-2 levels. We conclude that the apoptosis inhibitors Bcl-XL or Mcl-1, alone or in combination, may circumvent the normal cell death pathway, contributing to the pathogenesis and treatment resistance in metastatic MM.     

Splicing choice from ten variant exons establishes CD44 variability

The enormous heterogeneity of the surface protein designated CD44 is in part due to posttranslational modification, and in part due to differential splicing. Alternative splicing occurs within one particular region encoding the extracellular portion of the protein. Comparison of various cDNA clones with different 'inserts' in this variable region with sequences of genomic clones from the mouse has revealed the existence of at least ten exons from which sequences are chosen by alternative splicing. Various combinations of these exons account for the tremendous heterogeneity of CD44 molecules expressed in different tissues, and in progressing tumor cells. The existence of different isoforms of CD44 suggests a broad spectrum of yet unknown physiologic functions.     

Expression of CD44 variant v6 in breast carcinoma and its relationship with other parameters of tumor biology

BACKGROUND: The variant v6 of CD44 has been associated with metastatic behaviour in neoplasms such as lymphoma, colon carcinoma and breast carcinoma. The expression of CD44v6 in breast carcinoma by flow cytometry and its relationship with other tumor markers is studied in this paper. MATERIAL AND METHODS: The expression of CD44v6 was studied in 46 fresh tissue specimens by flow cytometry using a monoclonal antibody which recognizes the variant v6. Ploidy and cell cycle were also studied by flow-cytometry using propidium iodide labelling. p 53, c-erbB-2 and estrogen receptor expression as well as cell proliferation by Ki-67 staining were performed by immunohistochemistry. RESULTS: Nineteen out of 46 tumors were CD44v6 positive, without correlation with other tumor markers. Levels of CD44v6 in 19 positive samples sligtly correlates with S-phase and hystological grade. CONCLUSIONS: In the present study there was not a correlation among the presence of the variant v6 of CD44 on tumor cells from breast carcinoma and the aggressivity of the tumor. The expression of CD44v6 by flow cytometry does not seem to be a good prognostic marker.     

Involvement of CD44 in matrix metalloproteinase-2 regulation in human melanoma cells

CD44 is a family of cell-surface-adhesion proteins that are thought to play an important role in cancer invasion and metastasis. However, the specific mechanisms by which CD44 expression modulates invasion or metastasis are not well understood. In the current study, we have demonstrated that treatment of human melanoma cells with a CD44 MAb, F10-44-2, induces up-regulation of matrix metalloproteinase-2 (MMP-2) protein and mRNA. Moreover, treatment of melanoma cells with MAb F10-44-2 enhances their migration through gelatin-coated membranes and invasion through reconstituted basement membranes. Treatment of melanoma cells with several known CD44 ligands, including hyaluronate, extracellular-matrix proteins, and osteopontin, did not induce MMP-2 production. CD44 binding by F10-44-2 MAb results in induction of MMP-2 expression, which is associated with enhanced cell migration and invasion. These findings have several implications for investigations into tumor metastasis, development, and lymphocyte function.     

Expression and regulation of the porcine CD44 molecule

The expression and regulation of porcine CD44 were studied under various experimental conditions and in the context of lymphocyte differentiational and functional status. The CD44 molecule was subject to antigenic modulation by the anti-CD44 mAbs to different degrees depending on the type of cross-linking reagent and could be induced to shed from the cell surface. The reexpression of CD44 on papain-denuded lymphocytes was heterogeneous, as about half of the cells failed to resynthesize the molecule after prolonged culture, whereas the rest of the cells had a high turnover. Stimulation of lymphocytes by mitogens caused prolonged, dose-dependent elevation of the expression of CD44. Expression of CD44 on lymph node cells was found to be correlated with the expression of CD2 and sIgM. A CD2-CD4-sIgM-CD44-MHC Class IIhiCD45+ cell subset was identified, which was present in small numbers in lymph nodes but was enriched in gut-associated lymphoid tissues. In the thymus, CD44 expression seemed to be correlated with the differentiation status of thymocytes. In general, the expression of CD44 in the lymphoid tissues tested appeared to be related to their level of cell migration capacity.