Expression Of CD44 Variants Research Articles

Isolation and characterization of a hyaluronidase from the venom of Chinese red scorpion Buthus martensi

A hyaluronidase, named BmHYA1, was purified from the venom of Chinese red scorpion ( Buthus martensi), using successive chromatography. The homogeneity of BmHYA1 was confirmed by SDS-PAGE and MALDI-TOF mass spectrometry. The molecular mass of BmHYA1 was 48,696 Da determined by MALDI-TOF MS. The optimal temperature and pH of BmHYA1 were 50 °C and pH 4.5, respectively. It could be inhibited by DTT, Cu 2+, Fe 3+ or heparin, but not Mg 2+, Ca 2+, reduced glutathione, l-cysteine or EDTA. The sequence of thirty N-terminal amino acids of BmHYA1 was obtained by Edman degradation, as TSADF KVVWE VPSIM CSKKF KICVT DLLTS; but no similarity was found to other venom hyaluronidases. Further, BmHYA1 can hydrolyze hyaluronan into relatively smaller oligosaccharides and modulate the expression of CD44 variant in the breast cancer cell line MDA-MB-231.

In Vivo Evidence for the Role of CD44s in Promoting Breast Cancer Metastasis to the Liver

The hyaluronan receptor CD44 plays an important role in facilitating invasion and metastasis of a variety of tumors, including breast carcinomas. CD44 functions as a bioactive signaling transmitter. Although a number of studies have implicated CD44 in breast tumor invasion, the evidence is still circumstantial. We have developed a tetracycline-regulated CD44s (standard form) system in the weakly metastatic breast cancer cell MCF7, which exhibits low endogenous expression of CD44 and generated a new cell line, MCF7F-B5. Induction of CD44s alone affected the growth characteristics of MCF7F-B5 cells by increasing their abilities to proliferate, migrate, and invade in vitro. In addition, we have identified and validated cortactin as a novel transcriptional target of hyaluronan/CD44s signaling in underpinning breast tumor invasion. To test these observations in vivo, we developed a doxycycline (DOX)-regulated CD44s breast cancer xenograft model. Induction of CD44s did not affect the growth rate or local invasion of the primary tumor. However, although no mice from the +DOX group developed metastasis, 8 of 11 mice from the -DOX group developed secondary tumors to the liver only. Interestingly, metastatic breast tumors expressed high levels of CD44. This study provides in vivo evidence for the role of the standard form of CD44 in promoting breast tumor invasion and metastasis to the liver.

Expression of the Cell Adhesion Molecule CD44 in Human Lung Tumors and Cell Lines.

Background: The purpose of this study was to examine the expression of the cell adhesion molecule CD44 in normal lung, primary and metastatic lung tumors, and cell lines derived from primary lung carcinomas. Methods and Results: A total of 68 lung specimens including normal tissue and primary and metastatic tumors, as well as 28 cell lines cultured from primary lung tumors with high recurrence, were examined for CD44 expression by semiquantitative reverse transcription polymerase chain reaction. Variant exon expression was confirmed by Southern blotting and hybridization of particular samples. In tumor tissues, loss of CD44 variant expression correlated with increasing tumor stage; a smaller percentage of more aggressive and poorly differentiated tumors expressed CD44v. Tumors metastatic to the lung were negative for CD44 variant expression. In primary lung cell lines, as in tumor tissue, tumors of higher histologic grade were characterized by loss of CD44 variant expression. Conclusion: CD44 isoform expression in normal lung and tumor tissues and cell lines revealed an overall decrease in CD44 alternative splicing in lung neoplasms of increased malignancy.

The influence of CD44v3-v10 on adhesion, invasion and MMP-14 expression in prostate cancer cells

The expression of certain CD44 variants has been linked with metastasis and tumour progression. In particular, high molecular weight forms of CD44 show restricted expression in tumours and may correlate with tumour development and metastasis. In this study, we examined the expression of CD44 variants in prostate cancer cell lines: the invasive PC-3 and DU-145, low invasive LNCaP, and two non-invasive prostate epithelial cell lines. PC-3 prostate cancer cells were transfected with a high molecular weight CD44 variant isoform, CD44v3-v10, isolated from non-invasive prostate epithelial cell lines. These transfected cells (PC-NIVO) were assessed using in vitro invasion, tumour-endothelial, growth, and migration assays. The expression of MMP-14 was examined using SDS-PAGE and Western blot analysis. Transfected PC-3 cells (PC-NIVO) were found to be less adherent to endothelial cells and had significantly reduced invasiveness compared to wild-type PC-3 or control cells. In addition, tumour cell adhesion to endothelial cells and invasiveness was increased after exposure to HGF/SF, and can be blocked by the presence of anti-CD44 antibodies. Further investigation revealed a reduction in the expression of MMP-14 in PC-NIVO cells, but not in PC-3 or control cells. In conclusion, non-invasive prostate epithelial cells express a high molecular weight CD44 isoform, CD44v3-v10, which may counteract the standard isoform function of CD44 by reducing adhesion and invasion of endothelium by prostate tumour cells through negation of the MMP-14 function.

Enhanced cell surface CD44 variant (v6, v9) expression by osteopontin in breast cancer epithelial cells facilitates tumor cell migration: Novel post-transcriptional, post-translational regulation

Osteopontin (OPN) is a glycosylated, secreted phosphoprotein that functions both as a cell attachment and chemotactic factor. Elevated expression of OPN confers enhanced metastatic ability on transformed cells, suggesting that OPN may contribute to the malignant progression of tumors. Migration of mammary carcinoma cells is stimulated by OPN via interactions with integrins and CD44 cell surface receptors. We hypothesized that OPN modulates specific CD44 isoform expression to facilitate breast cancer cell migration. The 21NT tumorigenic human breast cancer cell line was examined for regulation of CD44 expression at both the mRNA and protein levels in response to an engineered increase in OPN expression under CMV promoter control. Significant up-regulation of CD44s isoform mRNA expression was observed, but no change in CD44v6, v8, v9 or v10 mRNA levels. While there were elevated levels of CD44s, v6 and v9 protein at the cell surface, at the level of total cellular protein only CD44s and v6 were markedly increased. This suggests that OPN can regulate CD44 expression at both transcriptional and post-transcriptional (both amount and localization of protein) levels. To validate the functional consequence of OPN regulation of CD44 expression, we demonstrate that OPN-mediated cell migration was reduced by exposure to a anti-pan CD44 antibody, and to anti-CD44v6 and anti-CD44v9 function-blocking antibodies. Our data provide evidence that in 21NT cells OPN enhances CD44s mRNA expression, increases cell surface expression of CD44 variant forms without a change in mRNA levels, and stimulates cell migration.

Endothelial adhesion of synchronized gastric tumor cells changes during cell cycle transit and correlates with the expression level of CD44 splice variants

To study adhesion capacity and CD44 expression of human gastric adenocarcinoma MKN45 cells at different stages of a first cell cycle. MKN45 cells were synchronized by aphidicolin and assayed for adhesion to an endothelial cell (HUVEC) monolayer. Surface expression of CD44 and CD44 splice variants on MKN45 cells was evaluated by flow cytometry. Functional relevance of CD44 adhesion receptors was investigated by blocking studies using anti CD44 monoclonal antibodies or by hyaluronan digestion. Adhesion of MKN45 to HUVEC was increased during G2/M transit, after which adhesion returned to baseline levels with cell cycle completion. In parallel, CD44 splice variants CD44v4, CD44v5, and CD44v7 were all up-regulated on MKN45 during cell cycle progression with a maximum effect in G2/M. The function of CD44 surface receptors was assessed with specific receptor blocking monoclonal antibodies or removal of hyaluronan by digestion with hyaluronidase. Both strategies inhibited tumor cell adhesion to HUVEC by nearly 50%, which indicates that MKN45-HUVEC-interaction is CD44 dependent. CD44 expression level is linked to the cell cycle in gastrointestinal tumor cells, which in turn leads to cell cycle dependent alterations of their adhesion behaviour to endothelium.

Enhanced Expression of CD44 Variants in Human Atheroma and Abdominal Aortic Aneurysm: Possible Role for a Feedback Loop in Endothelial Cells

CD44, a polymorphic hyaluronate receptor, may participate in chronic inflammation. We hypothesized that CD44 variants contribute to the development of arterial diseases. CD44 levels vary in normal and diseased arterial tissues in the following order: unaffected arteries < fibrous plaques < or = abdominal aortic aneurysm < atheromatous plaques; and correlate with macrophage content. Furthermore, plaque microvessels express CD44, and anti-CD44v3 or anti-CD44v6 treatment reduces endothelial cell proliferation but not apoptosis in vitro, suggesting functionality of these receptors. Endothelial cells express CD44H and CD44v6 after exposure to interleukin-1beta and tumor necrosis factor-alpha. Macrophages, a major source of abundant CD44 in vitro, express not only CD44H but also variants CD44v4/5, CD44v6, and CD44v7/8, isoforms distinctively regulated by proinflammatory cytokines. Several proinflammatory cytokines induce shedding of CD44 from the surface of macrophages and endothelial cells. Soluble CD44 stimulates the expression and release of interleukin-1beta from endothelial cells, suggesting a positive feedback loop of this cytokine. By demonstrating augmented expression of CD44 and variants within human atheroma and in abdominal aortic aneurysm as well as the vascular cell release of sCD44, a process regulated by proinflammatory cytokines, this study provides new insights on the functions of CD44 in arterial diseases.

Induction of CD44 and MMP expression by hyaluronidase treatment of articular chondrocytes.

In this study, the effects of fragmentation of the glycosoaminoglycans of the cell-associated matrix by hyaluronidase (HAase) on the expression of CD44 receptor and matrix metalloproteinase (MMP) mRNAs in cultured articular chondrocytes were examined. Chondrocytes, isolated from rabbit and bovine articular cartilage, were treated with bovine testicular HAase (0-200 units/ml) in the presence or absence of an antibody for CD44. The mRNA levels of CD44, CD44 variant (CD44v), MMPs (MMP-1, -3 and -9), and tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) were determined by RT-PCR. The treatment of cultured chondrocytes with HAase resulted in the production of low molecular weight fragments of hyaluronan (HA). The expression of CD44, CD44v and MMP (MMP-1, -3 and -9) mRNAs, but not TIMP-1 or TIMP-2 mRNA, was up-regulated in the cultures treated with HAase, whereas this expression was not affected by treatment with purified HA of 1.0 x 10(5) Da. Furthermore, the induction of CD44 and MMPs on treatment with HAase was suppressed by an anti-CD44 antibody. The results suggest that the fragmentation of HA may lead to cartilage destruction in terms of the enhanced expression of MMPs as well as the upregulation of CD44.

舌へん平上皮癌におけるＣＤ４４変異型の発現―免疫組織化学およびｉｎ ｓｉｔｕ ｈｙｂｒｉｄｉｚａｔｉｏｎによる検討―

CD44分子は選択的スプライシング機構により, 標準型CD44 (CD44 standard form, CD44s) と変異型CD44 (CD44 variant form, CD44v) を発現し, 癌転移との関連が報告されている。本研究の目的は, 舌癌におけるCD44sとCD44vの発現と頸部リンパ節転移との関連性を明らかにすることである。舌癌34症例の生検材料のホルマリン固定パラフィン包埋組織標本を用いてCD44s, CD44v4, CD44v5, CD44v6, CD44v7-8, CD44v9に対する抗体による免疫組織学的染色を行い, 陽性細胞の百分率によりCD44sとCD44vの発現の状態を評価した。34症例におけるCD44s, CD44v4, CD44v5, CD44v6, CD44v7-8, CD44v9の平均発現率はそれぞれ64.7%, 52.9%, 88.2%, 64.7%, 70.6%, 52.9%であった。頸部リンパ節転移陽性症例では非転移症例に比べてCD44v6, CD44v7-8の発現が有意に低下していた (P<0.05) 。また, ISHを用いてCD44v6 mRNAの発現について検討を行った。その結果, CD44v6 mRNAのシグナルは腫瘍細胞の核内および細胞質に顆粒状に認められ, 特に癌胞巣辺縁部の腫瘍細胞に多く発現していた。頸部リンパ節転移陽性症例では, CD44v6mRNAのシグナル発現が有意に低かった。 (P<0.05) 。変異型CD44の中で, v6, v7-8の検索は, 癌細胞の浸潤能, 転移能を予測するための重要な情報となり得ると考えられた。

Evaluation of CD44 variant 6 expression and clinicopathological factors in pulmonary metastases from colon carcinoma

Although relatively little is known about the molecular mechanisms underlying tumor progression, recently CD44 glycoproteins and the c-Met receptor tyrosine kinase have been identified as potentially important components of the metastatic cascade. CD44 is a family of transmembrane receptors generated from a single gene by alternative splicing and differential glycosylation. Important biological processes involving CD44 glycoproteins include cell adhesion, lymphocyte homing, hematopoiesis, tumor progression and metastasis. The precise mechanism via which CD44 promotes tumorigenesis have not yet been elucidated. We evaluated the expression of adhesion molecule CD44 variant 6 in pulmonary metastases from colorectal carcinomas and its correlation with clinicopathological parameters. Twenty patients were randomly selected from the patients who had undergone a resection of pulmonary metastasis from colorectal cancer. Formalin-fixed, paraffin-embedded archival specimens of tumor tissues and adjacent normal mucosa from these patients were the subjects of the present study. Immunoreactivity for CD44 was quantified. Specimens were considered positive if almost 25% of the neoplastic cells were stained. CD44 v6 expression was related to the interval between colon resection and metastases diagnosis, the number of pulmonary metastases, and the survival after lung resection. No statistical correlation was found between CD44 v6 positivity and disease-free interval after colon resection, number of metastases or 2-year survival after lung resection. Probably CD44 v6 is necessary and sufficient to confer metastatic potential to carcinoma cells increasing the migration capacity and participating in invasion via changes in adhesion to the extracellular ligands, but is not necessary to modify the clinical history of the metastases. Therefore the evaluation of CD44 v6 expression in lung metastases does not influence the therapeutic scheme.

Clinicopathological associations of CD44 mRNA and protein expression in primary breast carcinomas.

The purpose of this study was to examine the occurrence of CD44 isoforms in breast carcinomas and their role in predicting clinical outcome. Shock-frozen tumour tissues from 110 patients with breast carcinoma were examined by immunohistochemistry using antibodies directed against CD44s, v5, v6, v7 and v3-10. In addition, 80 of these tumours were available for quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of CD44s and CD44v6. Immunohistochemically, the positive tumours showed cytoplasmic and/or membranous staining with all antibodies. Staining results did not correlate with histological subtype, lymph node status, status of steroid receptors, tumour size or age. Neither was any correlation found for overall and disease-free survival. Quantitative real-time RT-PCR of CD44s and CD44v6, however, revealed that expression of CD44v6 mRNA was significantly associated with lower pathological grade (Pearson chi(2) test P = 0.009; linear-by-linear association P = 0.003). Linear-by-linear association between CD44s mRNA expression and lower pathological grade was also seen (P = 0.02). Survival analysis with the Kaplan-Meier method demonstrated that increased CD44s mRNA expression was significantly associated with both disease-free survival and overall survival (P = 0.0185 and P = 0.0344, respectively). A similar trend for CD44v6 mRNA expression was seen in these cases, but the difference was not significant. Quantitative real-time RT-PCR revealed clinical correlations of CD44s and CD44v6 mRNA expression in breast carcinomas while immunohistochemistry for the protein expression of CD44s and other CD44 variants did not. This contradictory result merits further studies concerning the clinical impact of CD44 molecules in breast carcinomas.

Expression of Membrane Type 1-Matrix Metalloproteinase and CD44 Variant 6 in Superficial Esophageal Squamous Cell Carcinoma

Expression of Membrane Type 1-Matrix Metalloproteinase and CD44 Variant 6 in Superficial Esophageal Squamous Cell Carcinoma

Distribution and expression of CD44 isoforms and Ezrin during prostate cancer-endothelium interaction

CD44 is a multifunctional cell surface adhesion molecule that has been implicated in tumour cell invasion and metastasis. Many cancer cell types as well as their metastases express high levels of CD44. Furthermore, the expression of certain CD44 variants has been linked with metastasis and tumour progression. It is known that ezrin, a member of the ERM family of proteins, can bind to CD44 and thus raises the possibility that it is involved in cell migration and metastasis. Therefore we examined the expression and distribution of CD44, its co-localisation and translocation with ezrin in prostate cancer cell lines as they interact with endothelial cells. Experimental results indicate prostate cancer cells express multiple CD44 isoforms that co-localise with ezrin in DU-145 and PC-3 prostate cancer cells. Treatment with hepatocyte growth factor (HGF/SF) resulted in up-regulation of CD44 and its co-translocation with ezrin during tumour-endothelial cell interactions. In addition, tumour cell adhesion to endothelial cells and their invasiveness was increased after exposure to HGF/SF, and can be blocked by the presence of anti-CD44 antibodies. It is concluded that CD44 and ezrin interact in endothelial cells and that they co-localise in the areas of tumour-endothelial contact. The CD44/ezrin complex plays a pivotal role in the capture and invasion of endothelial cells by prostate cancer cells.

Hyaluronidase reduces human breast cancer xenografts in SCID mice.

A hyaluronan-rich environment often correlate with tumor progression. and may be one mechanism for the invasive behavior of malignancies. Eradication of hyaluronan by hyaluronidase administration could reduce tumor aggressiveness and would provide, therefore, a new anti-cancer strategy. Hyaluronan interaction with its CD44 receptor and the resulting signal transduction events may be among the mechanisms for hyaluronan-associated cancer progression. We have shown previously that hyaluronidase treatment of breast cancer cells in vitro not only eradicates hyaluronan but also modifies expression of CD44 variant exons of tumor cells. We now determine if such effects occur in vivo and if it is accompanied by tumor regression. SCID mice bearing xenografts of human breast carcinomas were given intravenous hyaluronidase. Tumor volumes decreased 50% in 4 days. Tumor sections showed decreased hyaluronan. Intensity of staining for CD44s was not affected, whereas staining for specific CD44 variant exon isoforms was greatly reduced in residual tumors. Necrosis was not evident. Hyaluronidase, used previously as an adjunct in cancer treatment, presumably to enhance penetration of chemotherapeutic drugs, may itself have intrinsic anti-cancer activity. Removing peritumor hyaluronan appears to cause an irreversible change in tumor metabolism. Continuous hyaluronan binding to CD44 variant exon isoforms may also be required to stabilize inherently unstable isoforms that participate perhaps in tumor progression. Further investigation is required to confirm a cause and effect relationship between loss of hyaluronan, changes in CD44 variant exon expression and tumor reduction. If confirmed, hyaluronidase may provide a new class of anti-cancer therapeutics and one without toxic side effects.

Expression of CD44 variants in colorectal carcinoma quantified by real-time reverse transcriptasepolymerase chain reaction

CD44 is a family of transmembrane glycoproteins that has been linked to carcinogenesis and metastasis. It serves as a major receptor for hyaluronate. The v3 isoform binds to growth factors through heparan sulfate side chains and targets these factors to their high-affinity signal transducing receptors. The purpose of this study was to analyze the expression of CD44 v3 and v4 in human colorectal carcinoma with real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Our results show that 19 of 56 cases (33.9%) showed a greater than 2-fold increase in CD44 v3 expression in tumors as compared with matched normal mucosa, while 15 of 44 cases (34.1%) showed a greater than 2-fold increase in CD44 v4 expression. There was a marked variation in fold-differences of CD44 gene expression between tumor and normal samples (T/N ratios) among the tumors. This prompted us to correlate the T/N ratios of the tumors with clinicopathologic characteristics. Interestingly, overexpression of CD44 v3 mRNA was associated with the presence of vascular invasion (P <.05). Similarly, overexpression of CD44 v4 was significantly correlated to increased depth of invasion (P <.05). Results from the present study suggest that overexpression of CD44 v3 and v4 mRNA levels may be useful clinical markers for colorectal carcinoma invasiveness. (J Lab Clin Med 2002;139:59-65)

Significant correlations of E-cadherin, catenin, and CD44 variant form expression with carcinoma cell differentiation and prognosis of extrahepatic bile duct carcinomas.

To clarify the relation between alteration of expression of cell adhesion molecules and progression of extrahepatic bile duct carcinomas. 55 cases were immunohistochemically examined for E-cadherin, alpha-catenin, beta-catenin, and CD44, with additional reverse transcription-polymerase chain reaction and Southern blotting hybridization (RT-PCR/SBH) assays. Levels of E-cadherin, alpha-catenin, and beta-catenin proteins were lower in carcinomas than in normal mucosa, while CD44 variants 3 and 6 were upregulated. Well-differentiated carcinoma showed higher expression of E-cadherin and alpha-catenin than moderately to poorly differentiated types. Macroscopically papillary lesions had higher expression of E-cadherin than their nonpapillary counterparts. RT-PCR/SBH for CD44 revealed the CD44 variant form to be more prevalent in carcinoma than in normal mucosa, correlating with the immunohistochemical results, and with more exon variety. The Cox proportional hazards test identified histologic type and E-cadherin expression as prognostic factors. Among the examined molecules, E-cadherin was especially related to papillary mass formation and a good prognosis.

Expression of CD44 splice variants in spontaneous murine tumors.

CD44 is a widely distributed set of cell surface glycoproteins expressed in several types of cells and tissues, implicated in cell-cell and cell-substrate interactions. This molecule plays a major role in cell differentiation, development and activation and has also been described as a potential marker of malignancy and metastasis. In the present study we investigated by RT-PCR followed by exon specific amplification the expression of CD44 splice variants in four different murine tumors as well as in the invaded organs in order to correlate the expression of CD44 variants with potential tumor invasiveness and their implications for growth. Our data showed deregulation in the expression of CD44 isoforms but no discernible correlation in isoform expression pattern. However, in all tumors studied isoforms presented by the primary tumor were detected in the invaded organs before metastasis could be demonstrated by histopathological analysis.

Signal transduction via CD44 regulates CD44 variant isoform and β3 integrin expression and MMP-2 production

Signal transduction via CD44 regulates CD44 variant isoform and β3 integrin expression and MMP-2 production

Reduced expression of CD44 variant 9 is related to lymph node metastasis and poor survival in squamous cell carcinoma of tongue.

Expression of CD44v9 was immunohistochemically studied in 120 biopsy specimens from primary squamous cell carcinoma (SCC) of the tongue and correlated with clinicopathological findings of the SCCs. The tumors were classified into three groups according to immunostaining pattern of CD44v9; 53 cases with distinct positivity in all cancer cells except for those in the central part of nests (Group 1, non-reduced group), 42 cases with reduced expression in peripheral cells of nests (Group 2, reduced group), and 25 cases with complete disappearance of the expression in one or more nests (Group 3, negative group). Nineteen of 25 (76%) tumors in Group 3 and 14 of 42 (33%) in Group 2 exhibited lymph node metastasis, compared with only 8 of 53 (15%) in Group 1. The average survival time in Groups 1, 2 and 3 was 4496+/-204, 3866+/-379 and 2719+/-359 days, respectively and became shorter with the reduction of CD44v9 expression. These results suggest that the down-regulation of CD44v9 in SCC of the tongue may relate to the detachment of tumor cells from primary lesions, establishment of lymph node metastasis and consequently the death of patients.

Expression of CD44 variants in lung cancer and its relationship to hyaluronan binding.

We examined the expression of CD44 variant forms and their binding to hyaluronan (HA) in lung cancer cell lines. There was no relationship between the level of expression of CD44 variants and HA binding in different lung cancer cell lines. The expression of CD44v6 and CD44E in some cell lines was not always associated with HA binding. There was no relationship between the tissue pathological type and CD44 expression or HA binding. Deglycosylation by neuraminidase induced CD44-HA binding in human lung cancer cell lines. Our findings suggest that the HA binding ability of CD44, which is negatively regulated by glycosylation, might be a more important factor in tumorigenesis or metastasis than the expression of CD44 variant forms.