Expression Of Various Isoforms Research Articles

Role of protein kinase Cdelta in endothelin-induced type I collagen expression in cardiac myofibroblasts isolated from the site of myocardial infarction.

The role of endothelin-1 (ET) in tissue remodeling/fibrogenesis has been demonstrated in various in vitro and in vivo models. Our previous studies have revealed ET-induced expression of type I collagen in cardiac myofibroblasts (myoFb). Here we report that protein kinase Cdelta (PKCdelta) and mitogen-activated protein kinase/extracellular signal-regulated kinase-1/2 (MAPK/ERK1/2) play a role in ET-induced type I collagen expression using specific pharmacological inhibitors. The present study also reveals the expression of various isoforms of PKC including PKCalpha, PKCbetaI, PKCbetaII, PKCgamma, PKCdelta, PKCepsilon, PKCeta, and PKCzeta in cardiac myoFb. Our results from mRNA and protein studies demonstrate that calphostin-C, a PKC inhibitor, decreased the ET-induced type I collagen expression suggesting a role for the PKC pathway. Further treatment with rottlerin, a PKCdelta isoform-specific inhibitor, demonstrated attenuation of 80 to 90% of type I collagen expression induced by ET. However, Go6976 [12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo[2,3-a]pyrrolo [3,4-c]carbazole]], an inhibitor of Ca(2+)-dependent PKC isoforms (PKCalpha and PKCbetaI), showed little to no effect on ET-stimulated type I collagen expression. Furthermore, the MAPK inhibitor PD98059 (2'-amino-3'-methoxyflavone) attenuated ET-dependent activation of p44/42 MAPK (pERK1/2) and also down-regulated type I collagen expression. Similarly, rottlerin inhibited the activation of p44/42 MAPK (pERK) implicating the involvement of PKC and MAPK/ERK1/2 in ET-induced type I collagen expression. Our protein/DNA array and reverse transcription-polymerase chain reaction results from ET-treated samples showed a significant increase in Sp1 expression. PD98059 and rottlerin decreased ET-induced Sp1 expression, suggesting a possible interaction of Sp1 with PKCdelta and MAPK in ET-induced type I collagen expression in cardiac myoFb.

CD44 promotes resistance to apoptosis in human colon cancer cells

Overexpression of CD44, especially its variant isoforms, occurs consistently in colon cancer, as compared to autologous normal colon, and this change occurs also in most other types of cancer. One of the basic features of malignant transf ormation is the acquisition of resistance to apoptosis. In this study, we asked whether the expression of CD44 and some of its variant isoforms commonly found in colon cancer participate in resistance to apoptosis and what are the mechanisms involved. A human colon cancer cell line, SW620, which does not express CD44 was stably transfected with standard, v3-10, and v8-10 containing isoforms of CD44. Mock-transfected and CD44-transfected cells were exposed to etoposide to induce apoptosis. Apoptotic and concomitant changes relevant to the mechanisms of apoptosis were monitored by flow cytometry, DNA fragmentation, and immunoblot analyses. It was observed that resistance to apoptosis induced by etoposide is promoted by CD44 expression in SW620, and this resistance is better sustained by the full variant isoform, v3-10. Concomitant alterations in caspase 9, caspase 3, Bcl-xl, and Bak indicated that the resistance to apoptosis in this model involved the mitochondrial pathway. The differential response of CD44 transfectants was associated with a downregulation of pRb and phosphorylated AKT. The results of this study are consistent with the conclusion that expression of variant CD44 isoforms which is characteristic of colon cancer, and most other types of cancer, confers a selective advantage to resist apoptosis, thereby promoting cell transformation into a malignant phenotype, in conjunction with other anti-apoptotic factors.

Interaction of apoptosis signal-regulating kinase 1 with isoforms of 14-3-3 proteins

Apoptosis signal-regulating kinase 1 (ASK1) is a critical mediator of apoptotic signaling pathways initiated by a variety of death stimuli. Its activity is tightly controlled by various mechanisms such as covalent modification and protein–protein interaction. One of the proteins that control ASK1 function is 14-3-3ζ, a member of the 14-3-3 protein family. Here, we report that ASK1 is capable of binding to other isoforms of 14-3-3, suggesting that binding ASK1 is a general property of the 14-3-3 family. In support of this notion, mutational analysis revealed that the ASK1/14-3-3 interaction was mediated by the conserved amphipathic groove of 14-3-3 with some residue selectivity. Functionally, expression of various isoforms of 14-3-3 suppressed ASK1-induced apoptosis. To understand how 14-3-3 controls the ASK1 activity, we examined intracellular localization of ASK1 upon 14-3-3 co-expression. We found that 14-3-3 co-expression is correlated with the translocation of ASK1 from the cytoplasm to a perinuclear localization, likely the ER compartment. Consistent with this notion, ASK1 S967A, a 14-3-3 binding defective mutant of ASK, showed no change in intracellular distribution upon 14-3-3 co-expression. These data support a model that 14-3-3 proteins regulate the proapoptotic function of ASK1 in part by controlling its subcellular distribution.

Targeted Deletion of CD44v7 Exon Leads to Decreased Endothelial Cell Injury but Not Tumor Cell Killing Mediated by Interleukin-2-activated Cytolytic Lymphocytes

In the current study, we investigated the nature and role of CD44 variant isoforms involved in endothelial cell (EC) injury and tumor cell cytotoxicity mediated by IL-2-activated killer (LAK) cells. Treatment of CD44 wild-type lymphocytes with IL-2 led to increased gene expression of CD44 v6 and v7 variant isoforms and to significant induction of vascular leak syndrome (VLS). CD44v6-v7 knockout (KO) and CD44v7 KO mice showed markedly reduced levels of IL-2-induced VLS. The decreased VLS in CD44v6-v7 KO and CD44v7 KO mice did not result from differential activation and expansion of CD8+ T cells, NK, and NK-T cells or from altered degree of perivascular lymphocytic infiltration in the lungs. LAK cells from CD44v7 KO mice showed a significant decrease in their ability to adhere to and mediate lysis of EC but not lysis of P815 tumor cells in vitro. CD44v7-mediated lysis of EC by LAK cells was dependent on the activity of phosphatidylinositol 3-kinase and tyrosine kinases. Interestingly, IL-2-activated LAK cells expressing CD44hi but not CD44lo were responsible for EC lysis. Furthermore, lysis of EC targets could be blocked by addition of soluble or enzymatic cleavage of CD44v6-v7-binding glycosaminoglycans. Finally, anti-CD44v7 mAbs caused a significant reduction in the adherence to and killing of EC and led to suppression of IL-2-induced VLS. Together, this study suggests that the expression of CD44v7 on LAK cells plays a specific role in EC injury and that it may be possible to reduce EC injury but not tumor cell killing by specifically targeting CD44v7.

Motility of colon cancer cells: modulation by CD44 isoform expression

The invasion of cancer cells at primary tumor sites and their migration during metastatic spread require the expression of cell adhesion and motility proteins. Whether accelerated cell motility is necessary in these two processes is not universally accepted. In this study we took advantage that CD44, a cell adhesion protein, has different metastatic potentials depending on its splicing isoforms to examine how they affect cell motility. We established stable transfectants of standard and variant isoforms of CD44 in SW620 cells, a human colon carcinoma cell line that does not express CD44. The morphology of the cells varied according to the CD44 isoform expressed, but actin filament distribution remained unchanged. Using the wound assay in a two-dimensional in vitro cell motility system, we found that the expression of standard CD44 increases cell motility, whereas CD44 isoforms containing an exon sequence associated with metastatic dissemination has a slowing effect. Cell proliferation was also decreased by the expression of variant CD44 isoforms. Overall, colon cancer cells expressing variant CD44 isoforms had slower cell motility, possibly due to alterations in their cell adhesion properties. In conclusion, this study suggests that, contrary to common models, the metastatic phenotype is associated with a slow rate of cell migration when tested in vitro.

Transient CD44 Variant Isoform Expression and Reduction in CD4+/CD25+ Regulatory T Cells in C3H/HeJ Mice with Alopecia Areata

Alopecia areata, an autoimmune disease affecting anagen stage hair follicles, can be induced by grafting spontaneous alopecia areata affected skin to normal-haired C3H/HeJ mice. As the onset of alopecia areata can be significantly retarded by anti-CD44 variant isoform 10 treatment, it was interesting to explore the underlying disease mechanism. Two weeks after transplanting alopecia areata affected skin, expression of CD44 variant isoforms 3, 6, 7, and 10 was strikingly upregulated as compared with sham-grafted mice. By 6 wk after grafting, CD44 variant isoform levels had returned to normal, whereas in draining lymph nodes, CD44 variant isoform expression was slightly decreased. Leukocytes in the skin of mice with chronic alopecia areata expressed a hematopoietic isoform of CD44 and CD44 variant isoform 6 at an elevated level, but CD44 variant isoform 3 expression was reduced. Cytokine expression in leukocytes of chronic alopecia areata affected skin was higher than in normal-haired controls. Cytokine expression also increased postsurgery in sham and alopecia areata grafted mice, but remained elevated only in mice receiving alopecia areata affected skin. Finally, from the skin of mice with chronic alopecia areata and of mice transplanted with alopecia areata affected skin, an increased number of CD4(+) and CD8(+) cells, but a strongly decreased number of CD4(+)/CD25(+) regulatory T cells was recovered. Thus, expression of CD44 variant isoforms is important for the migration of leukocytes during the initial period of alopecia areata. CD44, however, is apparently not involved in the maintenance of the disease state, which is characterized by high cytokine expression levels, an increased number of CD4(+) and CD8+ cells, but a low level of CD4(+)/CD25(+) suppressor cells.

Proteolytic Cleavage of the CD44 Adhesion Molecule in Multiple Human Tumors

Cell surface adhesion molecules are crucial for the development and/or pathogenesis of various diseases including cancer. CD44 has received much interest as a major adhesion molecule that is involved in tumor progression. We have previously demonstrated that the ectodomain of CD44 undergoes proteolytic cleavage by membrane-associated metalloproteases in various tumor cell lines. The remaining membrane-bound CD44 cleavage product can be detected using antibodies against the cytoplasmic domain of CD44 (anti-CD44cyto antibody). However, the cleavage of CD44 in primary human tumors has not been investigated. Using Western blots with anti-CD44cyto antibody to assay human tumor tissues, we show that the CD44 cleavage product can be detected in 58% (42 of 72) of gliomas but not in normal brain. Enhanced CD44 cleavage was also found in 67% (28 of 42) of breast carcinomas, 45% (5 of 11) of non-small cell lung carcinomas, 90% (9 of 10) of colon carcinomas, and 25% (3 of 12) of ovarian carcinomas. Tumors expressing a CD44 splice variant showed a significantly higher incidence of enhanced CD44 cleavage. The wide prevalence of CD44 cleavage suggests that it plays an important role in the pathogenesis of human tumors.

Lysine hydroxylation and crosslinking of collagen.

Collagens represent a large family of structurally related extracellular matrix proteins containing unique triple helical structure. One of the characteristics of this structural protein is its extensive post-translational modifications that have major effects on molecular assembly, stability, and metabolism. Hydroxylation of specific lysine residues is one of such unique modifications found in collagen, and the pattern/extent of this modification influences fibrillogenesis, cross-linking, and matrix mineralization. The formation of covalent intermolecular cross-linking is the final modification in collagen biosynthesis and is critical for the stability of collagen. The process of cross-linking is dynamic and the pathways vary depending on the tissues and tissue's physiological state. This tissue specificity of cross-linking pattern may in part be the results of differential expression of various isoforms of lysyl hydroxylases and lysyl oxidases that have been recently identified and partially characterized. This chapter concentrates on recent research progress on these two modifications and the methods for analysis we have developed.

Role of Transforming Growth Factor-β1 and its Latent Form Binding Protein in Pseudoexfoliation Syndrome

Pseudoexfoliation (PEX) syndrome is a common and clinically important systemic condition characterized by the pathologic production and accumulation of an abnormal fibrillar extracellular material in many intra- and extraocular tissues. Recent evidence suggests that it is a type of elastosis associated with the excess synthesis of elastic microfibrillar components such as fibrillin-1. Since transforming growth factor (TGF)-β is a major modulator of extracellular matrix formation, the potential involvement of TGF-β and its latent form binding protein (LTBP) in this aberrant matrix process was investigated.The expression of various isoforms of TGF-β and LTBP was investigated in the anterior segment tissues of PEX and control eyes on the protein and mRNA level by light and electron microscopic immunohistochemistry, in situ hybridization, and semiquantitative RT-PCR. TGF-β1 and TGF-β2 levels were measured in aqueous humor and serum of PEX and control patients by ELISA. Cultures of Tenon's capsule fibroblasts were established to study the effect of TGF-β1 on fibrillin-1 mRNA expression by Northern blot analysis.Significantly increased concentrations of both total and active TGF-β1 were measured in the aqueous humor of PEX eyes without and with glaucoma as compared to control eyes, whereas levels of TGF-β2 were not significantly different. The expression of TGF-β1, LTBP-1, and LTBP-2, but not TGF-β2, was markedly increased in anterior segment tissues of PEX eyes, particularly in the non-pigmented epithelium of the ciliary body, on both the mRNA and the protein level. Latent TGF-β1 staining was consistently associated with PEX material deposits and could be released by proteolytic processing. Double immunolabeling revealed clear co-localization of LTBP-1 and -2 with latent TGF-β1 and with fibrillin-1 on PEX fibrils. The expression of mRNA coding for fibrillin-1 was up-regulated in vitro by TGF-β1.This study provides evidence for a significant role of TGF-β1 and the LTBPs 1 and 2 in PEX syndrome. The results suggest that increased levels of latent and active TGF-β1 in the aqueous humor of PEX patients, derived from enhanced local synthesis and activation, promote the buildup of the abnormal extracellular elastic material characteristic of PEX syndrome. They further support a dual role for LTBPs, both as integral structural components of PEX fibers and as a means of matrix anchorage of latent TGF-β1, representing one possible mechanism for the regulation of TGF-β1 activity in PEX eyes. Future therapeutic strategies might focus on TGF-β1 antagonistic approaches.

The influence of hormones on CD44 expression in endometrial and breast carcinomas

The expression of distinct variant isoforms of the cell surface glycoprotein CD44 (CD44v) has been found to be associated with metastatic potential of rodent adenocarcinoma cells and with an altered prognosis in several types of human cancer. In hormone-dependent gynecological cancers, different CD44v expression patterns have been observed. The influence of ovarian steroid hormones and their antagonists on CD44v expression is still unclear, since there are only retrospective correlation studies so far. Therefore, we examined the CD44 mRNA expression in a standardized stimulation experiment in a number of breast and endometrial carcinoma cell lines varying in estrogen receptor (ER) status. Higher CD44 overall expression was observed in ER positive endometrial and breast carcinoma cell lines when compared to corresponding ER negative cell lines. The number and composition of alternatively spliced isoforms showed no clear correlation to the ER expression status. Three CD44v isoforms were detected in all cell lines expressing CD44v, two of which have not been reported previously in normal endometrial cells. These isoforms may have specific functions in this type of carcinoma. In the second part of the study, the influence of (anti-) hormones on CD44 expression in endometrial carcinoma cell lines was examined. CD44 overall expression showed an increase when the cells were grown in medium containing fetal calf serum (FCS) as compared to cells maintained in medium-free of FCS. CD44 expression was transiently increased by estradiol (1 h). The CD44 splice pattern of endometrial cancer cell lines RL95-2 and Hec-1-A, after treatment with (anti-) hormones showed constant and high expression rates for distinct CD44v-isoforms such as CD44E (CD44v8-v10). Only certain weakly expressed isoforms changed their expression level during the experimental period, but no direct correlation to hormone treatment was observed. In conclusion, estradiol or FCS increase CD44 overall expression, but there seems to be no direct influence of ovarian steroid hormones on the CD44v splice machinery in endometrial carcinoma cell lines.

The prognostic significance of CD44s and CD44v6 expression in stage two breast carcinoma: an immunohistochemical study

Aims: Expression of the v6 variant isoform of CD44 has been causally associated with the development of metastases. This study, using immunohistochemical techniques, examined the prognostic significance of CD44s and CD44v6 expression. Methods: A cohort of 109 women presenting with stage 2 breast cancer, with a minimum follow-up of 5 years, were assessed. Results: Eighty percent of patients demonstrated CD44v6 expression on immunohistochemical studies. CD44v6 expression in tissue sections was found to be independent of age, tumour size, grade, and lymph-node status. No significant association was demonstrated between CD44v6 expression and either disease-free or overall survival. Similar findings were observed for CD44s. Conclusions: CD44s and CD44v6 do not appear to be useful as prognostic indicators in early breast cancer. The increased expression of variant CD44 isoforms seen in breast neoplasia may merely be a marker for loss of control of alternative splicing within tumour tissue.

Specific Splice Signals

STKE The generation of different proteins from a single gene by alternative splicing is regulated in a time-and tissue-specific manner. Although initiated by extracellular signals, transmission of such information from the cell surface to nuclear splicing machinery is not fully understood. Now Weg-Remers et al. have made some progress by looking at the expression of variant isoforms of CD44 on the surface of T cells. Activation of primary T cells initiated the ERK, JNK, and p38 MAP kinase signaling cascades. However, only activation of the Ras-ERK pathway was needed to generate a mature form of CD44 that included a particular exon. Mutation of the splice-responsive elements within this exon reduced expression of the CD44 isoform in response to ERK activation. Splicing did not depend on protein synthesis, suggesting that posttranslational modification of regulatory splice factors, possibly by phosphorylation, may regulate splicing. The specificity of exon selection could thus be determined in part by the activation of distinct signaling pathways. — LC EMBO J. 20 , 4194 (2001).

Specific Splice Signals

The generation of different proteins from a single gene by alternative splicing of pre-mRNA is a process that is regulated in a time- and tissue-specific manner. Although initiated by extracellular signals, transmission of such information from the cell surface to nuclear splicing machinery is not fully understood. Weg-Remers et al. have made some progress with respect to the expression of variant isoforms of CD44 on the surface of T cells. Activation of primary T cells initiated the ERK, JNK, and p38 MAP kinase signaling cascades. Yet, activation of only the Ras-ERK pathway was needed to generate a mature form of CD44 that included a particular exon. Mutation of the splice-responsive elements within this exon reduced expression of the CD44 isoform in response to ERK activation. Splicing did not depend on protein synthesis and the authors propose that posttranslational modification of regulatory splice factors, possibly by phosphorylation, regulates pre-mRNA splicing. The specificity of exon selection could thus be determined in part by the activation of distinct signaling pathways. S. Weg-Remers, H. Pona, P. Herrlich, H. Konig, Regulation of alternative pre-mRNA splicing by the ERK MAP-kinase pathway. EMBO J. 20 , 4194-4203 (2001). [Abstract] [Full Text]

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

CD44 isoform expression in synovial sarcoma correlates with epitheliogenesis but not prognosis.

We immunohistochemically determined the expression of CD44 standard and splice variant isoforms in a series of synovial sarcomas and sought correlations with histological subtype and clinical parameters including outcome. From 39 patients, a total of 56 formalin-fixed and paraffin-embedded tumour samples (including initial, recurrent and metastatic tumours) were used to immunohistochemically evaluate the expression of epitopes encoded by CD44s and the CD44 splice variants CD44v3-v10. Significance of proposed prognostic indicators was evaluated in relation to the survival, time to local recurrence and time to metastases using log-rank analysis. Sixty-four percent of synovial sarcomas expressed CD44s and 46% expressed CD44v3-v10 (var). Synovial sarcomas with epithelial or epithelioid areas preferentially expressed CD44s in these areas when compared with the spindle cell element. There were no correlations with clinical parameters or outcome. The expression of CD44 was not found to correlate with survival, local recurrence or metastatic ability. In synovial sarcoma, CD44 and variant isoform expression appears to be associated with the degree of epithelial differentiation. CD44 expression in synovial sarcoma shows interesting similarities to CD44 expression in embryological epitheliogenesis.

Expression of the cyclic AMP-dependent transcription factors, CREB, CREM and ATF2, in the human myometrium during pregnancy and labour.

Elevated concentrations of cyclic AMP (cAMP) in the human myometrium may promote uterine quiescence during pregnancy by protein kinase A (PKA)-mediated phosphorylation and subsequent inactivation of myosin light-chain kinase, as well as by the phosphorylation and activation of cAMP-dependent transcription factors. In this context, we show that the altered expression of cAMP response-element binding protein (CREB), cAMP response-element modulator protein (CREM) and activating transcription factor 2 (ATF2) are implicated in the maintenance of myometrial quiescence during fetal maturation and the switch to uterine activation at term. Using electrophoretic mobility shift and super shift assays, as well as immunoblotting of paired myometrial tissue samples from non-pregnant, pregnant non-labouring and spontaneous labouring women, we defined the patterns of expression of various isoforms of these proteins in the human uterus. Here, we report spatio-temporal changes in the expression of a 43 kDa form of CREB, a 28 kDa CREM-like protein, and a novel 28 kDa ATF2-like protein which are differentially expressed, depending on the gestational state of the uterus. Changes in the pattern of expression of these potent transcription factors may have an important role in the control of uterine activity throughout pregnancy.

Upregulation of CD44 expression in the retina during the rds degeneration

In adult mouse retinas the standard form of the cell surface adhesion/receptor molecule CD44 is localized to Müller cell apical microvilli. In the rds (retinal degeneration slow) mouse, however, CD44 immunolabel is increased and distributed throughout the retina by 3 months postnatal. At present, it is unclear if this labeling pattern is due to the increased expression of standard CD44, the expression of variant CD44 isoforms, or an unmasking of CD44 antigenic sites. To further characterize this response, we have studied the expression of CD44 mRNA and protein in rds retinas of different ages. RT-PCR analysis demonstrated one product which represented the message for standard CD44 in adult BALB/c mouse retina and in all ages of rds retinas studied. Upon Southern blotting, this major product was detected along with two minor bands of larger size in all samples. Northern blot analysis demonstrated a major transcript of approximately 4.0 kb and a minor one of 3.0 kb in all BALB/c and rds retinas. By 3 months postnatal in rds retinas, the expression of CD44 message was increased by at least two-fold. Western blot analysis demonstrated the presence of only the standard form of CD44 protein in all BALB/c and rds retinas. An increased amount of this standard CD44 protein was observed in 2, 3, and 6 month rds retinas. Thus, this study demonstrates that the inherited retinal degeneration exhibited by the rds mouse does not cause an altered expression of retinal CD44 isoforms, but does lead to an upregulation in the expression of mRNA and protein for standard CD44.

Altered Expression of CD44 and Variant Isoforms in Human Adenocarcinoma of the Endocervix during Progression

Objective. Altered expression of the CD44 family of cell adhesion molecules has been associated with tumor progression and metastasis. The aim of this study was to investigate the expression of the gene products of CD44 standard (CD44s) and several alternatively spliced variants (CD44v4, v6, v7, and v9) in adenocarcinoma of the endocervix and to correlate the degree of their expression with disease progression.Methods. Immunohistochemical staining for CD44s and CD44v4, v6, v7, and v9 was performed on formalin-fixed, paraffin-embedded endocervical specimens. Seventeen cases of adenocarcinoma in situ (AIS) and 22 cases of invasive adenocarcinoma of the endocervix were included in this study, and the immunoreactivity was compared with that of normal endocervical epithelium.Results. (1) In the normal endocervical mucosa, immunoreactivity for CD44s and the splice variants was lacking or was confined to only the basal portion of the glandular epithelium along the basement membrane; (2) CD44s was diffusely expressed along the entire cytoplasmic membrane, including the luminal surface of the tumorous glands in 94% of AIS and 95% of invasive adenocarcinomas; (3) a significantly stronger expression of CD44s was observed in invasive adenocarcinomas than in AIS; (4) in contrast to all other splice variants, CD44v9 demonstrated an increased expression in nearly all in situ and invasive lesions compared to the normal tissue; (5) CD44v4 and v6 were expressed only in a small proportion of invasive adenocarcinomas and were near totally absent in the in situ lesions; and (6) CD44 v7 was totally absent in all normal, in situ, and invasive lesions studied.Conclusions. It appears that neoplastic transformation of endocervical epithelium is associated with qualitative and quantitative changes in the expression of CD44 standard molecule and some CD44 splice variants.

Ratio of CD44 epithelial variant to CD44 hematopoietic variant is a useful prognostic indicator in gastric and colorectal carcinoma.

The CD44 is a cell adhesion molecule that is present as numerous isoforms created by mRNA alternative splicing. Expression of variant isoforms of CD44 is associated with tumor growth and metastasis. The aim of this study was to evaluate whether CD44 isoform expression is a prognostic factor in gastric and colorectal cancer. We performed a polymerase chain reaction analysis following reverse transcriptase treatment for CD44 expression in fresh surgical specimens obtained from 25 colon carcinomas and 30 gastric carcinomas and matched adjacent normal mucosa. We determined the epithelial variant/hematopoietic variant (E/H) ratio (the amount of the CD44 epithelial variant transcript relative to the CD44 hematopoietic variant transcript) in cancer tissues and examined it for correlations with clinicopathological parameters and survival rate. The E/H ratio in tumor tissue was significantly higher than that in adjacent non-cancerous mucosa. In gastric and colorectal cancer tissues, there was no significant relationship between E/H ratio and clinicopathological parameters. However, patients who died due to tumor recurrence had a higher E/H ratio than surviving patients with colorectal cancer. In gastric cancer, patients with high E/H tumors had a shorter survival time than those with low E/H tumors. Our results suggest that the E/H ratio is a useful indicator of prognosis in gastric and colorectal carcinoma.

CD44v3 and v6 variant isoform expression correlates with poor prognosis in early-stage vulvar cancer.

Expression of alternatively spliced CD44 isoforms has been reported to correlate with poor prognosis in human squamous cell cancers, i.e. squamous cell cancer of the lung and cervix. The aim of this study was to evaluate whether CD44 isoform expression is a prognostic factor in early-stage squamous cell cancer of the vulva. Seventy cases of squamous cell carcinoma of the vulva International Federation of Gynaecology and Obstetrics (FIGO) stage I were examined immunohistochemically for expression of CD44 isoforms. We used four different variant exon sequence-specific murine monoclonal antibodies to epitopes encoded by exons v3, v5, v6 and v7-8 of human variant CD44. The correlation of CD44 expression with histological grade and disease-free and overall survival was investigated. CD44 isoforms CD44v3, CD44v5, CD44v6 and CD44v7-8 were detected in 28% (20/70), 47% (33/70), 33% (23/70) and 17% (12/70) of the tumour samples respectively. Patients suffering from tumours expressing CD44v6 had a poorer relapse-free (log-rank test, P = 0.02) and overall survival (log-rank test, P = 0.03). Likewise, patients suffering from tumours expressing CD44v3 had a poorer relapse-free (log-rank test, P = 0.04) and overall survival (log-rank test, P = 0.01). Expression of CD44v5 and CD44v7-8 did not compromise the patients' outcome. Histological grade did not correlate with CD44 isoform expression. Immunohistochemically detected expression of CD44 isoforms containing variant exon v6 or v3 is correlated with a poor relapse-free and overall survival in FIGO stage I vulvar cancer patients.