CD44 Transcripts Research Articles

Annexin A2 regulates Mycoplasma bovis adhesion and invasion to embryo bovine lung cells affecting molecular expression essential to inflammatory response.

Mycoplasma bovis (M. bovis) is an important pathogen of the bovine respiratory disease complex, invading lower respiratory tracts and causing severe pneumonia. However, its molecular mechanism largely remains unknown. Host annexin A2 (ANXA2) is a calcium-dependent phospholipid-binding protein. The current study sought to determine whether ANXA2 could mediate M. bovis adhesion and invasion thereby affecting its induction of inflammatory response. ANXA2 expression was upregulated in M. bovis-infected bovine lung epithelial cells (EBL), and blocking ANXA2 with an anti-ANXA2 antibody reduced M. bovis adhesion to EBL. Compared with uninfected cells, more ANXA2 was translocated from the cytoplasm to the cell surface after M. bovis infection. Furthermore, RNA interference knockdown of ANXA2 expression in EBL cells resulted in a significant decrease in M. bovis invasion and F-actin polymerization. Next, the transcriptomic study of M. bovis-infected EBL cells with and without ANXA2 knockdown were performed. The data exhibited that ANXA2 knockdown EBL cells had 2487 differentially expressed genes (DEGs), with 1175 upregulated and 1312 downregulated compared to control. According to GO and KEGG analyses, 50 genes potentially linked to inflammatory responses, 23 involved in extracellular matrix (ECM) receptor interaction, and 48 associated with PI3K-AKT signal pathways were upregulated, while 38 mRNA binding genes, 16 mRNA 3′-UTR binding genes, and 34 RNA transport genes were downregulated. Furthermore, 19 genes with various change-folds were selected for qPCR verification, and the results agreed with the RNA-seq findings. Above all, the transcription of two chemokines (IL-8 and CXCL5) and a key bovine β-defensin TAP in IL-17 signaling pathway were significantly increased in ANXA2 knockdown cells. Moreover, ANXA2 knockdown or knockout could increase NF-κB and MAPK phosphorylation activity in response to M. bovis infection. Additionally, ANXA2 knockdown also significantly decreased the CD44 transcripts via exon V3 and V7 skipping after M. bovis infection. We concluded that M. bovis borrowed host ANXA2 to mediate its adhesion and invasion thereby negatively regulating molecular expression essential to IL-17 signal pathway. Furthermore, CD44 V3 and V7 isoforms might contribute to this ANXA2 meditated processes in M. bovis infected EBL cells. These findings revealed a new understanding of pathogenesis for M. bovis infection.

Hyaluronated and PEGylated Liposomes as a Potential Drug-Delivery Strategy to Specifically Target Liver Cancer and Inflammatory Cells.

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and is characterized by poor clinical outcomes, with the majority of patients not being eligible for curative therapy and treatments only being applicable for early-stage tumors. CD44 is a receptor for hyaluronic acid (HA) and is involved in HCC progression. The aim of this work is to propose HA- and PEGylated-liposomes as promising approaches for the treatment of HCC. It has been found, in this work, that CD44 transcripts are up-regulated in HCC patients, as well as in a murine model of NAFLD/NASH-related hepatocarcinogenesis. Cell culture experiments indicate that HA-liposomes are more rapidly and significantly internalized by Huh7 cells that over-express CD44, compared with HepG2 cells that express low levels of the receptor, in which the uptake seems due to endocytic events. By contrast, human and murine macrophage cell lines (THP-1, RAW264.7) show improved and rapid uptake of PEG-modified liposomes without the involvement of the CD44. Moreover, the internalization of PEG-modified liposomes seems to induce polarization of THP1 towards the M1 phenotype. In conclusion, data reported in this study indicate that this strategy can be proposed as an alternative for drug delivery and one that dually and specifically targets liver cancer cells and infiltrating tumor macrophages in order to counteract two crucial aspect of HCC progression.

MRNA expression analysis confirms CD44 splicing impairment in systemic lupus erythematosus patients.

Systemic Lupus Erythematosus (SLE) is a complex chronic autoimmune disease characterized by several immunological alterations. T cells have a peculiar role in SLE pathogenesis, moving from the bloodstream to the peripheral tissues, causing organ damage. This process is possible for their increased adherence and migration capacity mediated by adhesion molecules, such as CD44. Ten different variant isoforms of this molecule have been described, and two of them, CD44v3 and CD44v6 have been found to be increased on SLE T cells compared to healthy controls, being proposed as biomarkers of disease and disease activity. The process of alternative splicing of CD44 transcripts is not fully understood. We investigated the mRNA expression of CD44v3 and CD44v6 and also analyzed possible CD44 splicing regulators (ESRP1 molecule and rs9666607 CD44 polymorphism) in a cohort of SLE patients compared to healthy controls. This study involved 18 SLE patients and 18 healthy controls. Total RNA and DNA were extracted by peripheral blood mononuclear cells. The expression study was conducted by quantitative RT-polymerase chain reaction, using SYBR Green protocol. Genotyping of rs9666607 SNP was performed by direct sequencing. CD44v6 mRNA expression was higher in SLE patients compared to healthy controls (p = 0.028). CD44v3/v6 mRNA ratio in healthy controls was strongly unbalanced towards isoform v3 compared to SLE patients (p = 0.002) and decreased progressively from healthy controls to the SLE patients in remission and those with active disease (p = 0.015). The expression levels of CD44v3 and CD44v6 mRNA correlated with the disease duration (p = 0.038, Pearson r = 0.493 and p = 0.038, Pearson r = 0.495, respectively). Splicing regulator ESRP1 expression positively correlated with CD44v6 expression in healthy controls (p = 0.02, Pearson r = 0.532) but not in SLE patients. The variant A allele of rs9666607 of CD44 was associated with higher level of global CD44 mRNA (p = 0.04) but not with the variant isoforms. In SLE patients, the increase in CD44v6 protein correlates with a higher transcript level of this isoform, confirming an impairment of CD44 splicing in the disease, whose regulatory mechanisms require further investigation.

Expression analysis of CD24 and CD44 transcripts in Iranian breast cancer patients.

The importance of cancer stem cells (CSCs) in initiation and progression of breast cancer has been well established. This population of cells is characterized by high expression of CD44 and low expression of CD24. However, the relative abundance of CD24 and CD44 transcripts in breast cancer tissues and adjacent non-cancerous tissues (ANCTs) has not been quantified yet. In the present investigation, we assessed expression of CD24 and CD44 at transcript level in breast cancer tissues and ANCTs in association with clinical determinants of patients' outcome and parameters that predict response to therapeutic options. There was no significant difference in expression of CD24 and CD44 in breast cancer tissues compared with ANCTs (Expression ratios: 1.03 and 0.84, P values: 0.92 and 0.61, respectively). However, CD44 expression was associated with tumor size in a way this gene was up-regulated in all of small sized (≤2cm) tumors compared with the corresponding ANCTs (P value = 0.04). Besides, CD44 expression was significantly higher in tumors with extracapsular nodal extension compared with those without extension (P =0.04). Expression of CD24 was higher in grade3 tumors compared with grade 2 tumors (P =0.04). Expression levels of CD24 and CD44 were correlated with each other in ANCTs but not in tumoral tissues. The current study shows another aspect of CSC markers in the development of breast cancer.

Prognostic Significance of TWIST1, CD24, CD44, and ALDH1 Transcript Quantification in EpCAM-Positive Circulating Tumor Cells from Early Stage Breast Cancer Patients.

(1) Background: The aim of the study was to evaluate the prognostic significance of EMT-associated (TWIST1) and stem-cell (SC) transcript (CD24, CD44, ALDH1) quantification in EpCAM+ circulating tumor cells (CTCs) of early breast cancer patients. (2) Methods: 100 early stage breast cancer patients and 19 healthy donors were enrolled in the study. CD24, CD44, and ALDH1 transcripts of EpCAM+ cells were quantified using a novel highly sensitive and specific quadraplex RT-qPCR, while TWIST1 transcripts were quantified by single RT-qPCR. All patients were followed up for more than 5 years. (3) Results: A significant positive correlation between overexpression of TWIST1 and CD24−/low/CD44high profile was found. Kaplan–Meier analysis revealed that the ER/PR-negative (HR-) patients and those patients with more than 3 positive lymph nodes that overexpressed TWIST1 in EpCAM+ cells had a significant lower DFI (log rank test; p < 0.001, p < 0.001) and OS (log rank test; p = 0.006, p < 0.001). Univariate and multivariate analysis also revealed the prognostic value of TWIST1 overexpression and CD24−/low/CD44high and CD24−/low/ALDH1high profile for both DFI and OS. (4) Conclusions: Detection of TWIST1 overexpression and stem-cell (CD24, CD44, ALDH1) transcripts in EpCAM+ CTCs provides prognostic information in early stage breast cancer patients.

Isolation of all CD44 transcripts in human epidermis and regulation of their expression by various agents

Isolation of all CD44 transcripts in human epidermis and regulation of their expression by various agents

Identification of CD44 transcripts that segregate with proliferation, redox and differentiation activities in human epidermal keratinocytes

Identification of CD44 transcripts that segregate with proliferation, redox and differentiation activities in human epidermal keratinocytes

Isolation of All CD44 Transcripts in Human Epidermis and Regulation of Their Expression by Various Agents.

CD44, a cell surface proteoglycan, is involved in many biological events. CD44 transcripts undergo complex alternative splicing, resulting in many functionally distinct isoforms. To date, however, the nature of these isoforms in human epidermis has not been adequately determined. In this study, we isolated all CD44 transcripts from normal human epidermis, and studied how their expressions are regulated. By RT-PCR, we found that a number of different CD44 transcripts were expressed in human epidermis, and we obtained all these transcripts from DNA bands in agarose and acrylamide gels by cloning. Detailed sequence analysis revealed 18 CD44 transcripts, 3 of which were novel. Next, we examined effects of 10 different agents on the expression of CD44 transcripts in cultured human keratinocytes, and found that several agents, particularly epidermal growth factor, hydrogen peroxide, phorbol 12-myristate 13-acetate, retinoic acid, calcium and fetal calf serum differently regulated their expressions in various patterns. Furthermore, normal and malignant keratinocytes were found to produce different CD44 transcripts upon serum stimulation and subsequent starvation, suggesting that specific CD44 isoforms are involved in tumorigenesis via different CD44-mediated biological pathways.

Immunophenotype and gene expression profiles of cell surface markers of mesenchymal stem cells derived from equine bone marrow and adipose tissue

Bone marrow and adipose tissue are the two main sources of mesenchymal stem cell (MSC). The aim of this work was to analyse the immunophenotype of 7 surface markers and the expression of a panel of 13 genes coding for cell surface markers in equine bone marrow and adipose tissue-derived MSCs obtained from 9 horses at third passage. The tri-lineage differentiation was confirmed by specific staining. Equine MSCs from both sources were positive for the MSC markers CD29 and CD90, while were negative for CD44, CD73, CD105, CD45 and CD34. The gene expression of these molecules was also evaluated by reverse transcriptase real-time quantitative PCR along with the expression of 5 other MSC markers. Both populations of cells expressed CD13, CD29, CD44, CD49d, CD73, CD90, CD105, CD106, CD146 and CD166 transcripts. Significant differences in gene expression levels between BM- and AT-MSCs were observed for CD44, CD90, CD29 and CD34. Both cell types were negative for CD45 and CD31. The surface antigens tested revealed a similar phenotypic profile between horse and human MSCs, although specific differences in some surface antigens were noticed.

The epithelial splicing factors ESRP1 and ESRP2 positively and negatively regulate diverse types of alternative splicing events

Cell-type and tissue-specific alternative splicing events are regulated by combinatorial control involving both abundant RNA binding proteins as well as those with more discrete expression and specialized functions. Epithelial Splicing Regulatory Proteins 1 and 2 (ESRP1 and ESRP2) are recently discovered epithelial-specific RNA binding proteins that promote splicing of the epithelial variant of the FGFR2, ENAH, CD44, and CTNND1 transcripts. To cataloge a larger set of splicing events under the regulation of the ESRPs we profiled splicing changes induced by RNA interference-mediated knockdown of ESRP1 and ESRP2 expression in a human epithelial cell line using the splicing sensitive Affymetrix Exon ST1.0 Arrays. Analysis of the microarray data resulted in the identification of over a hundred candidate ESRP regulated splicing events. We were able to independently validate 37 of these targets by RT-PCR. The ESRP regulated events encompass all known types of alternative splicing events, most prominent being alternative cassette exons and splicing events leading to alternative 3’ terminal exons. Importantly, a number of these regulated splicing events occur in gene transcripts that encode proteins with well-described roles in the regulation of actin cytoskeleton organization, cell-cell adhesion, cell polarity, and cell migration. In sum, this work reveals a novel list of transcripts differentially spliced in epithelial and mesenchymal cells, implying that coordinated alternative splicing plays a critical role in determination of cell type identity. These results further establish ESRP1 and ESRP2 as global regulators of an epithelial splicing regulatory network.

Neuronal expression of Cd36, Cd44, and Cd83 antigen transcripts maps to distinct and specific murine brain circuits

Cells recruited by the innate immune response rely on surface-expressed molecules in order to receive signals from the local environment and to perform phagocytosis, cell adhesion, and others processes linked to host defense. Hundreds of surface antigens designated through a cluster of differentiation (CD) number have been used to identify particular populations of leukocytes. Surprisingly, we verified that the genes that encode Cd36 and Cd83 are constitutively expressed in specific neuronal cells. For instance, Cd36 mRNA is expressed in some regions related to circuitry involved in pheromone responses and reproductive behavior. Cd44 expression, reanalyzed and detailed here, is associated with the laminar formation and midline thalamic nuclei in addition to striatum, extended amygdala, and a few hypothalamic, cortical, and hippocampal regions. A systemic immune challenge was able to increase Cd44 expression quickly in the area postrema and motor nucleus of the vagus but not in regions presenting expressive constitutive expression. In contrast to Cd36 and Cd44, Cd83 message was widely distributed from the olfactory bulb to the brain stem reticular formation, sparing the striatopallidum, olivary region, and cerebellum. Its pattern of expression nevertheless remained strongly associated with hypothalamic, thalamic, and hindbrain nuclei. Unlike the other transcripts, Cd83 mRNA was rapidly modulated by restraint stress. Our results indicate that these molecules might play a role in specific neural circuits and present functions other than those attributed to leukocyte biology. The data also suggest that these surface proteins, or their associated mRNA, could be used to label neurons in specific circuits/regions.

Frequent expression of the high molecular, 673-bp CD44v3,v8-10 variant in colorectal adenomas and carcinomas

CD44 is a transmembrane glycoprotein involved in the interaction between cells and the extracellular matrix. A large variety of alternatively spliced CD44 variants are expressed by different tumors with possible implication for tumor progression, formation of metastasis and survival. In colon carcinomas, previous reports described higher molecular bands of CD44 transcripts in neoplastic colonic tissue, although a complete analysis of multiple combinations of CD44v transcripts were not performed. We therefore analyzed the pattern of CD44 standard and variant (v2-v10) transcripts in colorectal adenomas and carcinomas by exon-specific RT-PCR amplification and sought CD44v transcripts specific for colonic neoplasias. Our data indicate that CD44 standard transcripts, including the epithelial form (C-v8,v9,v10-C) corresponding to a 720 bp transcript, were detected in 2/38 (5.2%) samples of normal mucosa, 20/20 (100%) adenomas and in 21/33 (63%) colorectal carcinomas. High molecular CD44v3,v8-10 (673 bp) transcripts were found in 2/33 (6%) samples from normal mucosa, 19/20 (95%) from adenomas and in 29/31 from colorectal carcinomas (93%). Similar CD44v3,v8-10 transcripts were detected in five from seven colorectal liver metastases, while normal liver did not contain high molecular CD44v3 variants. The same CD44v3,v8-10 (673 bp) variant was detected in HT-29 human colon carcinoma cells. Direct sequencing of the CD44v3 (673 bp) transcript in samples from colorectal carcinomas and HT-29 cells confirmed the assumed CD44v (-C-v3-v8-v9-v10-C-) cDNA sequence. Analysis of other CD44 variant transcripts (v4-v10) using exon specific primers were less frequently associated with colorectal neoplasias. These data report for the first time frequent expression of neoplasia-associated CD44v3,v8-10 variants in colorectal adenomas and carcinomas supporting the role of increased CD44 variant expression as an early event in colorectal carcinogenesis. The described CD44v3,v8-10 (673 bp) variant might be relevant for diagnosis and treatment of colorectal cancer.

Macrophage Migration Inhibitory Factor Induces B Cell Survival by Activation of a CD74-CD44 Receptor Complex

Macrophage migration inhibitory factor (MIF) is an upstream activator of innate immunity that regulates subsequent adaptive responses. It was previously shown that in macrophages, MIF binds to a complex of CD74 and CD44, resulting in initiation of a signaling pathway. In the current study, we investigated the role of MIF in B cell survival. We show that in B lymphocytes, MIF initiates a signaling cascade that involves Syk and Akt, leading to NF-kappaB activation, proliferation, and survival in a CD74- and CD44-dependent manner. Thus, MIF regulates the adaptive immune response by maintaining the mature B cell population.

SHAP Potentiates the CD44-mediated Leukocyte Adhesion to the Hyaluronan Substratum

CD44-hyaluronan (HA) interaction is involved in diverse physiological and pathological processes. Regulation of interacting avidity is well studied on CD44 but rarely on HA. We discovered a unique covalent modification of HA with a protein, SHAP, that corresponds to the heavy chains of inter-alpha-trypsin inhibitor family molecules circulating in blood. Formation of the SHAP.HA complex is often associated with inflammation, a well known process involving the CD44-HA interaction. We therefore examined the effect of SHAP on the CD44-HA interaction-mediated lymphocyte adhesion. Under both static and flowing conditions, Hut78 cells (CD44-positive) and CD44-transfected Jurkat cells (originally CD44-negative) adhered preferentially to the immobilized SHAP.HA complex than to HA. The enhanced adhesion is exclusively mediated by the CD44-HA interaction, because it was inhibited by HA, but not IalphaI, and was completely abolished by pretreating the cells with anti-CD44 antibodies. SHAP appears to potentiate the interaction by increasing the avidity of HA to CD44 and altering their distribution on cell surfaces. Large amounts of the SHAP.HA complex accumulate in the hyperplastic synovium of rheumatoid arthritis patients. Leukocytes infiltrated to the synovium were strongly positive for HA, SHAP, and CD44 on their surfaces, suggesting a role for the adhesion-enhancing effect of SHAP in pathogenesis.

Association of CD45dimVLA-4+ cells with the NKT cell lineage and their selective expression of IL-13, IP-15, and CCR3 transcripts

Estrogen (E2) was shown to prevent experimental autoimmune encephalomyelitis (EAE) and to produce a novel population of regulatory CD45(dim)VLA-4(+) cells. Although their appearance was dependent upon an elevated hormonal level, E2 was not required for their production, as they also were induced by immunization with Mycobacterium tuberculosis as a component of complete Freund's adjuvant. Molecular techniques, including ribonuclease protection assays and quantitative RT-PCR, were used to provide further characterization of CD45(dim)VLA-4(+) cells. Moreover, we determined the developmental requirements of the CD45(dim)VLA-4(+) cells using genetically modified mice and extensive flow cytometry analysis. Characterization of CD45(dim)VLA-4(+) mRNA profile revealed highly elevated levels of CD16, CD44, CCR3, IP-15, and IL-13 transcripts compared with their CD45(high)VLA-4(+) counterparts. Furthermore, we found up-regulation of anti-apoptotic bcl-w and bcl-xl genes and transcripts encoding the TCRalpha and CD8alpha homodimer. The production of CD45(dim)VLA-4(+) cells was evident in nude mice and in MHC class II- and beta2-microglobulin, but not in CD1-deficient mice, suggesting a crucial role for CD1 in their induction. These findings suggest that CD45(dim)VLA-4(+) cells might resemble natural killer T cells and imply possible roles for IL-13 and IP-15 in the protective function of CD45(dim)VLA-4(+) cells. A better understanding of how these cells, also occurring naturally during pregnancy, suppress the harmful immune response of EAE may lead to novel therapeutic approaches to combat multiple sclerosis and other autoimmune diseases.

Accumulation of Immature Intron-containing CD44 Gene Transcripts in Breast Cancer Tissues.

Background: Disorderly expression of the CD44 gene is a characteristic feature of many common types of human malignancy. The explanation for the diversity, abundancy, and abnormally large size of the resulting transcripts is under investigation. Methods and Results: This study used reverse transcription-polymerase chain reaction (RT-PCR)/Southern blot hybridization to examine the expression of the CD44 gene in fresh tissue samples from 21 breast cancers and 11 matched non-neoplastic breast tissue specimens from the same patients. Using probes for several exons and for a noncoding region (intron 9) of the gene, it was found that the previously described elevated levels of CD44 transcripts in malignant tumors of this organ include many unusual, alternatively spliced isotypes as well as immature forms that retain this intron and probably several others. All of the exons that were tested were involved in the disorderly overexpression of this gene observed in all of the cancer tissues, and we were able to detect retention of the intron 9 sequence in 14 (67%) of the 21 tumor samples. In contrast, it was possible to detect signals in only 3 (27%) of the 11 samples from nonmalignant breast tissue with this probe, and these were extremely faint. Conclusions: These findings imply that there is a profound disorder in the regulation of production, splicing, and processing of CD44 pre-mRNA in breast cancer tissues comparable to that described in tumors of many other organs. The clinical implication of this information is that analysis of tissue samples containing borderline or suspected premalignant lesions for the presence of these molecular abnormalities, which appear to be characteristic of neoplasia, may in due course help assessment of individual patient prognosis and optimization of treatment.

The role of CD44 in the development and prognosis of head and neck squamous cell carcinomas.

CD44, the product of a single gene, exists as several isoforms generated by alternative exon splicing and posttranslational modifications, and is widely distributed in different cells and tissues including those of squamocellular origin. CD44 is a cell surface glycoprotein involved in many cellular processes acting as a receptor for cell to cell or cell to matrix adhesion, as a signal transmitter and as a growth factor-presenting molecule. Numerous studies based on immunohistochemical analyses of paraffin-embedded or frozen tissue sections using different monoclonal antibodies to CD44 isoforms and molecular biological techniques have provided evidence that in many types of tumours there is overexpression of CD44 isoforms and aberrant processing of immature CD44 transcripts relative to non-neoplastic control tissues, suggesting a role of CD44 in tumour development and progression. In contrast to these malignancies, one or more of the CD44 splice-variant isoforms are down-regulated in squamous cell carcinomas of the head and neck. CD44-deficient mice develop normally without giving rise to spontaneous tumours, but CD44-negative cells appear to be more susceptible to oncogenic transformation. Reduction in the expression of CD44 may confer growth advantage and malignant properties to tumour cells. The clinical significance of CD44 in squamous cell carcinomas of the head and neck as a tumour marker for cancer diagnosis and prognosis is discussed.

Limitations of CD44v6 amplification for the detection of tumour cells in the blood of colorectal cancer patients.

Based on the important role of CD44 splice variants in colorectal cancer progression and metastasis, we evaluated the use of CD44v6 expression to detect and assess the metastatic potential of colorectal tumour cells circulating in peripheral blood. A nested amplification was designed that allowed to detect 10–100 colon cancer cells. This assay was applied to blood samples from healthy donors. Strong signals were detected in all cases, indicating that it cannot be used to detect colorectal carcinoma cells in whole blood. We then included an enrichment step based on the use of an anti-epithelial cells monoclonal antibody (BerEP4) coupled to magnetic beads. The CD44v6 reverse transcription polymerase chain reaction (RT PCR) assay was performed on cDNA synthesized from blood samples treated with these beads. We analysed 18 samples from 12 patients with a gastrointestinal disease, and 36 samples from ten patients with a colorectal cancer. None of the patients used as negative controls were found to contain epithelial cells in their blood as determined by cytokeratin 19 RT-PCR. By contrast, CD44 transcripts containing exon v6 were detected in nine out of the 18 samples tested (50%). For the colorectal cancer patients, six out of the seven samples (85.7%) that were cytokeratin 19-positive were CD44v6-negative, whereas ten samples out of the 29 not containing epithelial cells were CD44v6-positive (34.5%). This is probably due to the persistence of CD8+ leucocytes in the enriched preparations, as determined by PCR analysis of the CD8 α-chain. We conclude that detection of CD44v6 transcripts using a sensitive nested RT-PCR assay has no potential value to detect and characterize colorectal cancer micrometastases from blood, even following an initial enrichment step. © 2000 Cancer Research Campaign

The expression and clinical significance of CD44v in human gastric cancers.

CD44 was originally implicated as a “homing” receptor directing the migration of recirculating lymphocytes[1]. CD44 expression has been confirmed not only in lymphocytes but also in a wide variety of epithelial tissues. It is considered as an important cell adhesion molecule for cell to cell interactions[2]. Molecular cloning and analysis of the genetic structure have revealed that the CD44 gene has at least 19 exons, of which 12 can be alternatively spliced to make up a wide variety of CD44 splice variants which have been found in various types of human malignancies and have been considered as a marker in tumor progression and metastasis[3]. We analysed the expression of aberrant CD44 transcripts with RT-PCR method in gastric carcinomas, and discussed the clinical significance of metastasis-related CD44v gene.

CD44 expression in benign, premalignant, and malignant ovarian neoplasms: relation to tumour development and progression.

To clarify the possible role of CD44 expression in ovarian tumour development and progression, an immunohistochemical investigation was undertaken of a series of 115 carcinomas, 32 tumours with low malignant potential (LMP), and 53 cystadenomas. A combination of the reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot hybridization (SBH) assays was also performed for 17 malignant, four LMP, six cystadenoma, and seven normal ovarian samples. Immunoreactivity scores for CD44s, CD44v3, and CD44v6 were significantly higher in LMP and malignant tumours than in the benign or normal cases, in line with the results of gross mRNA-based assays. Exon-specific RT-PCR/SBH assays revealed that the expression of large CD44 transcripts containing v6 to v8 exons and small isoforms containing v2 and v3 was common among normal and neoplastic tissues, while a simultaneous increase of large isoforms containing v2 to v5 was also revealed in LMP and malignant tumours. In ovarian carcinomas, the scores for CD44s, CD44v3, and CD44v6 were inversely related to the FIGO stage, but there was no association with lymph node status or expression of hormone receptors. Multivariate analysis revealed loss of CD44v3 expression to be an independent factor for poor survival. The findings indicate that CD44 is up-regulated during the development of ovarian carcinomas but is subsequently down-regulated during their progression, resulting in aggressive behaviour and an unfavourable prognosis.