Progression in gastric carcinoma relative to the ratio of CD44 epithelial variant transcript to CD44 hematopoietic variant transcript

Sulfasalazine, a therapeutic agent for ulcerative colitis, inhibits the growth of CD44v9(+) cancer stem cells in ulcerative colitis-related cancer

BACKGROUND AND OBJECTIVE

Sulfasalazine reduces the risk of ulcerative colitis (UC)-related cancer through its anti-inflammatory effect and induction of oxidative stress in cancer cells by inhibiting the glutamate-cystine transporter, which is closely associated with the cancer stem cell surface marker CD44v9. This study aimed to quantify the effects of sulfasalazine on CD44v9 expression and pathological factors in colorectal cancers (CRCs) arising from UC.

METHODS

Twenty-six patients with UC-related cancer were classified into groups according to the length of sulfasalazine treatment as follows: (1) long-term (LT) (≥ 5 years) and (2) short-term (ST) (< 5 years). Using immunohistochemistry, we compared CD44v9 and Ki-67 expression and pathological characteristics of each group's tumors. In vitro assay was performed to investigate the effect of sulfasalazine on epithelial differentiation and proliferation of CD44(+) cancer cells.

RESULTS

Immunohistochemical analysis revealed that CD44v9 expression tended to be lower in the LT group (LT:ST=15.4%:46.2%, P=0.20), and Ki-67/CD44v9 double-stained cells were significantly lower in the LT group (LT:ST=0%:6.9%, P=0.01). Pathologically, the frequency of well-differentiated adenocarcinomas was higher in the LT group (LT:ST=84.6%:38.5%, P=0.04). In vitro assay revealed that sulfasalazine promoted the expression of epithelial differentiation markers (E-cadherin and CDX2) and inhibited the proliferation of CD44(+) cancer cells.

CONCLUSIONS

Long-term sulfasalazine administration reduced proliferative CD44v9(+) cells and increased the degree of differentiation of adenocarcinomas. These findings indicate the importance of CD44v9(+) cells in UC-related cancer progression and suggest that sulfasalazine may serve as a novel therapeutic agent that targets CD44v9(+) cells.

Rapid and reliable detection of CD44 variants in gastric carcinoma using a nested reverse transcription-polymerase chain reaction

The present study aimed to establish a rapid and reliable method for detecting the expression of cluster of differentiation 44 variant (CD44v) in gastric carcinoma, and to investigate the significance of CD44v in gastric carcinoma. Using a nested reverse transcription-polymerase chain reaction (RT-PCR) technique, the expression of CD44v and CD44v8-10 was analyzed in gastric cancer tissues (128 cases), precancerous lesions (19 cases of atypical hyperplasia and 6 cases of intestinal metaplasia) and corresponding adjacent non-cancerous tissues (153 cases). The tumor and non-cancerous biopsy samples of 153 patients were analyzed using nested RT-PCR. All the PCR products included bands at 482 bp, demonstrating positive CD44 expression. By contrast, the CD44v band (>600 bp) was observed in 132/153 total tumor samples (86.3%), including 114/128 gastric cancer samples (89.1%), 16/19 atypical hyperplasia samples (84.2%) and 2/6 intestinal metaplasia samples (33.3%). However, 18/153 non-cancerous tissues samples (11.8%) exhibited a CD44v band. Thus, CD44v expression was significantly higher in gastric cancer tissues and precancerous lesions compared with that of adjacent non-cancerous tissues (P<0.05). Furthermore, there was a significant difference in CD44v8-10 expression detected between gastric cancer and adjacent non-cancerous tissue samples (P<0.05). Among the 25 patients with precancerous lesions, 8/19 atypical hyperplasia cases and 1/6 intestinal metaplasia cases were positive for CD44v8-10 expression. The difference in the CD44v8-10 expression rate among the various pathological types of gastric cancer (n=128) cases was not significant (P>0.05). Additionally, immunohistochemical analysis identified CD44v positivity (++) in 59/76 (77.6%) cases of gastric cancer and 5/12 (41.1%) cases of atypical hyperplasia. The CD44v and CD44v8-10 PCR products were confirmed by sequencing analysis. The results of the present study indicated that nested RT-PCR technology may be exploited as a method for gastric carcinoma diagnosis.

Regulation of CD44E by DARPP-32-dependent activation of SRp20 splicing factor in gastric tumorigenesis

Objective

CD44E is a frequently overexpressed variant of CD44 in gastric cancer. Mechanisms that regulate CD44 splicing and expression in gastric cancer remain unknown. Herein, we investigated the role of DARPP-32 (dopamine and cAMP-regulated phosphoprotein, Mr 32000) in promoting tumor growth through regulation of CD44 splicing.

Design

Quantitative luciferase reporter, quantitative real-time RT-PCR (qRT-PCR), Western blot, co-immunoprecipitation, ubiquitination, and tumor xenograft experiments were performed.

Results

Western blot and qRT-PCR results indicated that knockdown of endogenous DARPP-32 markedly reduces expression of CD44 V8-V10 (CD44E). Using a quantitative splicing luciferase reporter system, we detected a significant increase in the reporter activity following DARPP-32 overexpression (p < 0.001). Conversely, knocking down endogenous DARPP-32 significantly attenuated the splicing activity (p < 0.001). Further experiments showed that DARPP-32 regulates the expression of SRp20 splicing factor and co-exists with it in the same protein complex. Inhibition of alternative splicing with digitoxin followed by immunoprecipitation and immunoblotting indicated that DARPP-32 plays an important role in regulating SRp20 protein stability. The knockdown of endogenous DARPP-32 confirmed that DARPP-32 regulates the SRp20-dependent CD44E splicing. Using tumor xenograft mouse model, knocking down endogenous DARPP-32 markedly reduced SRp20 and CD44E protein levels with a decreased tumor growth. The reconstitution of SRp20 expression in these cells rescued tumor growth. In addition, we also demonstrated frequent co-overexpression and positive correlation of DARPP-32, SRp20 and CD44E expression levels in human gastric primary tumors.

Conclusion

Our novel findings establish for the first time the role of DARPP-32 in regulating splicing factors in gastric cancer cells. The DARPP-32–SRp20 axis plays a key role in regulating the CD44E splice variant that promotes gastric tumorigenesis.

Functional role of CD44v-xCT system in the development of spasmolytic polypeptide-expressing metaplasia

Cancer development is often preceded by the appearance of preneoplastic lesions. In gastric carcinogenesis, chronic inflammation and histopathologic progression of the stomach epithelium lead to the development of metaplasia and eventually adenocarcinoma. The cell surface protein CD44, especially its variant isoforms (CD44v), has been implicated in metaplasia-carcinoma sequence progression in the stomach. We recently found that CD44v interacts with and stabilizes xCT, a subunit of the cystine transporter system xc(-), in cancer cells and thereby increases cystine uptake and confers resistance to various types of cellular stress in vivo. The functional relevance of CD44v and xCT in the development of preneoplastic lesions, however, has remained unknown. We have now examined the role of the CD44v-xCT system in the development of spasmolytic polypeptide-expressing metaplasia (SPEM) in mouse models of gastric carcinogenesis. CD44v was found to be expressed de novo in SPEM, and CD44v(+) metaplastic cells manifested upregulation of xCT expression compared with CD44v(-) cells. Genetic ablation of CD44 or treatment with sulfasalazine, an inhibitor of xCT-dependent cystine transport, suppressed the development of SPEM and subsequent gastric tumor growth. Therapy targeted to CD44v-xCT could thus prove effective for prevention or attenuation of the CD44v-dependent development of preneoplastic lesions and cancer.

Significance of site-specific prognosis of cancer stem cell marker CD44 in head and neck squamous-cell carcinoma

In several recent studies, CD44 expression has been associated with aggressive behavior in cancers of different types. CD44 expression is also linked to cancer stem cells, which have been shown to play a significant role in tumor progression and poor prognosis in head and neck squamous cell carcinoma (HNSCC), as well as in other cancers. Although CD44 is a potential prognostic marker, it has not been adopted to wider clinical use as a part of treatment planning in HNSCC patients. The aim of this research was to study whether CD44 overexpression is associated with 5year overall survival in HNSCC. We also studied site-specific associations between increased CD44 expression and 5year overall survival. Associations between relative tumor CD44 expressions and smoking, heavy alcohol consumption, histological grade of cancer, TNM staging and HNSCC staging were also studied. In total, 135 paraffin-embedded blocks from HNSCC patients were stained immunohistochemically with a CD44 antibody and were classified by the anatomic location of the tumor. CD44 overexpression had statistically significant association with decreased 5year survival rates when all HNSCC samples were studied (p<0.001). Significant association between intense CD44 expression and poor 5year survival rates was found in the patients with SCC of the oro- and hypopharynx (p<0.001) and the larynx (p=0.042). In patients suffering from HNSCC in the oral cavity, CD44 overexpression did not have a significant effect on overall 5year survival rates. Heavy smoking of over 10 pack years had a significant association with tumor CD44 overexpression (p=0.009). Only pharyngeal (p=0.046) and laryngeal (p=0.047) SCC, but not oral-cavity SCC, had statistically significant associations between heavy smoking and CD44 overexpression when HNSCC was studied in regional groups. Alcohol consumption and tumor grade did not have a significant association with the tumor's CD44 expression. Our results suggest that CD44 overexpression could be used as a sign of aggressiveness, in addition to the HNSCC staging, as a prognostic factor in pharyngeal and laryngeal HNSCC and to assist in treatment selection.

Paxillin predicts survival and relapse in non-small cell lung cancer by microRNA-218 targeting

Paxillin (PXN) gene mutations are associated with lung adenocarcinoma progression and PXN is known to be a target gene of microRNA-218 (miR-218). On this basis, we hypothesized that PXN overexpression via miR-218 suppression may promote tumor progression and metastasis and that PXN may predict survival and relapse in non-small cell lung cancer (NSCLC). Expression of miR-218 and PXN in 124 surgically resected lung tumors were evaluated by real-time PCR and immunohistochemical analysis. The prognostic value of miR-218 and PXN expression on overall survival (OS) and relapse-free survival (RFS) was analyzed by the Kaplan-Meier test and Cox regression analysis. miR-218 expression in lung tumors was negatively associated with PXN expression. Multivariate analyses showed that PXN and miR-218 might independently predict OS and RFS, respectively, in NSCLC. Moreover, patients with low miR-218 combined with PXN-positive had the worst OS and RFS among the 4 combinations. In a cell model, PXN was negatively regulated by miR-218 and cell proliferation, invasion, and soft agar colony formation were enhanced by PXN overexpression induced by miR-218 suppression. Taken together, our findings suggest that PXN overexpression induced by miR-218 suppression is an independent predictor of survival and relapse in NSCLC, highlighting PXN as a potential therapeutic target to improve clinical outcomes in this disease.

CD44+ slow-cycling tumor cell expansion is triggered by cooperative actions of Wnt and prostaglandin E2 in gastric tumorigenesis

Similar to normal tissue stem cells, cancer stem cells (CSCs) are thought to be quiescent or slow-cycling and, thereby, insensitive to chemo- and radiotherapies. CD44, a cell surface component that interacts with the extracellular matrix, has been found to be highly expressed in CSCs of several solid tumors. However, the relevancy between CD44(+) cells and slow-cycling cells and the underlying mechanisms for the emergence of CD44(+) CSCs during tumorigenesis have not been elucidated. Here we show that a gastric gland residing at the squamo-columnar junction (SCJ) in normal mouse stomach contains CD44(+) stem cell-like slow-cycling cells and that this characteristic CD44(+) gland was expanded by prostaglandin E2 (PGE(2)) and Wnt signaling in K19-Wnt1/C2mE mouse, a genetic mouse model for gastric tumorigenesis. The analysis of three transgenic mouse lines, K19-Wnt1, K19-C2mE and K19-Wnt1/C2mE, revealed that the expansion of CD44(+) SCJ cells is triggered by PGE(2)-mediated signaling and is prominently enhanced by the addition of Wnt activation. Furthermore, each expanded CD44(+) gland in gastric tumor of K19-Wnt1/C2mE mouse contains a few BrdU label-retaining quiescent or slow-cycling cells, suggesting that the CD44(+) SCJ cells in normal mouse are candidates for the cell-of-origin of gastric CSCs. These observations suggest that PGE(2)-mediated inflammatory signaling and Wnt signaling cooperatively trigger the expansion of CD44(+) slow-cycling stem-like cells in SCJ, leading to development of lethal gastric tumors in mice.

Expression and prognostic relevance of CD44v6 in stage I non-small cell lung carcinoma

PURPOSE

Expression of CD44 and its variants has been shown to be relevant to tumor progression in various human malignancies. We evaluated the expression of CD44v6 in the primary lesions of stage I non-small cell lung cancer (NSCLC) and correlated the expression level to its prognosis.

METHODS

The expression of CD44v6, measured by immunohistochemistry, was assessed in the tumor specimens from 190 patients with stage I NSCLC. Each slide was assigned a score: the average of the score of tumor cells staining multiplied by the score of staining intensity. And depending on the cut-off score based on receiver operating characteristic (ROC) curve analysis, the CD44v6 expression was categorized into high- and low-level groups, which were then correlated directly with the clinical outcomes.

RESULTS

The high expression of CD44v6 was detected more frequently in the squamous cell carcinoma (38 of 71 patients, 53.5%) than in the other types of carcinoma (p < 0.05). The Kaplan-Meier survival curves showed that high level expression of CD44v6 indicated a better post-operative survival (p = 0.006), especially for stage IB disease (p = 0.049) and squamous cell carcinoma (p = 0.029). The multivariate analysis also confirmed that the expression of CD44v6 was an independent prognostic indicator (p = 0.011).

CONCLUSIONS

CD44v6 might be correlated with histogenesis of NSCLC, and its decreased expression may be an adverse prognostic indicator for the patients with stage I NSCLC, especially for those with stage IB diseases. Patients of this subgroup might need adjuvant therapy additionally.

The prognostic value of adhesion molecule CD44v6 in women with primary breast carcinoma: a clinicopathologic study

AIMS

CD44 functions as an adhesion molecule. Within the family of CD44 isoforms, the spliced variant 6 has been causally associated with the development of metastases and poor prognosis in animal models and several human cancers. The aim of this study was to investigate the prognostic value of CD44v6 in women with primary breast carcinoma.

MATERIALS AND METHODS

The women with primary breast carcinoma in this study were followed up clinically for a period of 5 years. Clinicopathologic features, including tumour size, axillary nodal status, histological grade and pTNM stage, were determined for a cohort of 78 women presenting with primary breast carcinoma. Standard immunohistochemistry was used to explore CD44v6 expression. The data obtained were analysed by univariate and multivariate analyses.

RESULTS

Forty-three out of 78 (55%) women with breast carcinoma were CD44v6-positive (i.e. over 5% of tumour cells exhibited positive staining). Significant sequential increase of CD44v6 expression was observed in women with metastases of axillary nodes, tumour size more than 2 cm, advanced pTNM stage and survival period less than 5 years. Univariate analysis showed that axillary nodal status, primary tumour size, histological grade, and pTNM stage were associated with 5-year survival, and CD44v6 expression was associated with primary tumour size, axillary nodal status, pTNM stage and 5-year survival. In multivariate analysis, using the Cox-regression model, CD44v6 expression was not an independent prognostic factor.

CONCLUSIONS

CD44v6 expression was correlated with tumour size, metastases of axillary nodes, pTNM stage, and 5-year survival; however, multivariate analysis revealed that CD44v6 expression failed to be an independent predictor of patient prognosis.

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

AIMS

The purpose of this study was to examine the occurrence of CD44 isoforms in breast carcinomas and their role in predicting clinical outcome.

METHODS AND RESULTS

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.

CONCLUSIONS

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.

Reduced expression of CD44 v3 and v6 is related to invasion in lung adenocarcinoma

We have previously reported that the histological pattern of invasion is correlated with the prognosis of surgically treated patients of lung adenocarcinoma. On the other hand, several clinicopathologic studies have shown that CD44 variant isoforms are associated with invasion and metastasis in human malignant tumors. The expression of CD44 variant isoforms v3 and v6 was analyzed in 93 Japanese lung adenocarcinoma patients by immunostaining to study the relationship between their expression and the invasion in lung adenocarcinoma. The specimens were histologically categorized into three groups. Both the invasive lesion and the noninvasive lesion were observed in 49 out of 93 cases (group I). Twenty cases were noninvasive carcinoma growing mainly in a lepidic pattern (group II). Twenty-three cases were invasive carcinoma which showed no frankly noninvasive lesion growing in a lepidic pattern (group III). The significant reduced expression of CD44 v3 and v6 was observed in the invasive lesion compared with the noninvasive lesion in adenocarcinoma of group I (P < 0.05). Although reduced expression of CD44 v3 and v6 was observed in the invasive carcinoma of group III compared with the noninvasive carcinoma of group II, it was not significant (P = 0.0693 for v3, P = 0.0827 for v6). The pattern of expression of CD44 v3 was significantly concordant with that of CD44 v6 (P < 0.0001). Our results suggest that reduced expression of CD44 v3 and v6 is associated with the invasion in the lung adenocarcinoma.

CD44 variant exons in leukemia and lymphoma

CD44 is a cell surface glycoprotein expressed on different cell types that functions in lymphocyte activation and homing, extracellular matrix adhesion and cellular migration. CD44 is encoded by a single gene composed of at least 20 exons. The standard CD44 protein (CD44S or CD44H) is the hematopoietic form of CD44 in lymphoid cells. Variant isoforms (designated from v1 to v10) are formed by addition of new exons to the extracellular domain. High levels of CD44v6 expression has been observed in some tumors and are associated with metastatic spread. The aim of the present study was to investigate and evaluate expression of the CD44v6 and v6-containing variants as a possible marker in chronic myeloid leukemia and lymphoma by reverse transcription-polymerase chain reaction. CD44 exon v6 was detected in all patients and all individuals in the control group. CD44v6-v10 mRNA was observed in 25 patients but in none of the subjects in the control group. CD44v6/v9-10, CD44v6-v7, CD44v6/v10 transcripts were detected in 11, 6, and 2 patients, respectively. CD44v6-7/v9-10 transcripts were not observed in either the patients or the healthy individuals. We conclude that CD44v6-v10 expression may be associated with hematologic malignancies.

Expression of CD44 isoforms in infiltrating lobular carcinoma of the breast

Expression of CD44 has been shown to correlate with the progression and prognosis of some malignant tumors. The aim of this study was to evaluate the expression of CD44 isoforms in infiltrating lobular carcinomas and analyse their potential as prognostic indicators. A panel of 39 tumors were examined for their expression of membranous and cytoplasmic CD44s, v3, v5, v6, v7 and v3-10 in the infiltrating cells, by immunohistochemical staining. The protein positive tumors showed membranous and/or cytoplasmic staining with all antibodies used except for CD44v7, which only displayed cytoplasmic staining. Cytoplasmic expression of CD44v3 (P = 0.014) and membranous expression of v6 (P = 0.039) were significantly associated with alveolar, classical/alveolar carcinomas and mucinous/alveolar carcinomas. Furthermore, in alveolar, classical/alveolar and mucinous/alveolar carcinomas, cytoplasmic staining of CD44v5 was correlated with lymph node negative patients (P = 0.048), whereas membranous v5 was correlated with lymph positive patients (P = 0.048). In classical, classical/trabecular and trabecular carcinomas expression of membranous CD44s was significantly correlated with lymph node status (P = 0.042).

Tumor suppressor gene, cell surface adhesion molecule, and multidrug resistance in Müllerian serous carcinomas: clinical divergence without immunophenotypic differences

OBJECTIVES

We hypothesize that differences in the expression of selected tumor suppressor genes, cell surface adhesion molecules, and multidrug resistance glycoproteins could account for some of the reported differences between uterine serous carcinoma (USC) and extrauterine serous carcinomas (ESC), including ovarian and primary peritoneal carcinoma (OSC and PSC, respectively).

METHODS

We studied the expression of the following antigens in 20 USCs, 20 OSCs, and 10 PSCs: p53 and mdm-2 (tumor suppressor genes), CD44 and CD44v6 (cell surface adhesion molecules), and the p-glycoprotein (a multidrug resistance protein recognized by two antibodies, C494 and JSB1). We further studied chemotherapeutic drug resistance by examining reports prepared using the Oncotech Extreme Drug Resistance Assay from 24 of the 50 study patients. Clinical data were obtained from medical record review.

RESULTS

USC, OSC, and PSC patients were similar with respect to mean age at diagnosis, mean gravidity, mean parity, personal history of breast cancer, percentage treated with chemotherapy, and survival at 3 and 5 years postdiagnosis. Significant clinical differences included a high prevalence of nulliparity in OSC (P = 0.05), a low prevalence of Caucasian race in USC (P = 0.008), a paucity of stage I patients in OSC and PSC (P = 0.03), a high prevalence of familial breast cancer in OSC (P = 0.06), and superior 2-year survival in OSC (P = 0.02). Seventy-five percent of USCs, 52% of OSCs, and 60% of PSCs expressed p53. Five percent of USCs, 19% of OSCs, and 0% of PSCs expressed mdm-2. Forty percent of USCs, 33% of OSCs, and 10% of PSCs expressed CD44. None of the USCs, OSCs, or PSCs expressed CD44v6. Sixty-one percent of USCs and OSCs and 82% of PSCs expressed C494 while 17% of USCs, 19% of OSCs, and 20% of PSCs expressed JSB1. None of these apparent differences was statistically significant. USC, OSC, and PSCs patients did not demonstrate significant differences with respect to extreme drug resistance. However, the following trends were noted (P = 0.06): more prevalent low drug resistance for cyclophosphamide in OSC compared with USC and more prevalent extreme drug resistance for etoposide in OSC compared with USC.

CONCLUSIONS

Therefore, despite significant clincial differences, the USCs and ESCs in our series do not differ significantly with respect to the expression of the tumor suppressor genes, cell surface adhesion molecules, and drug resistance proteins studied. It is premature, however, to recommend that USCs and ESCs should be treated identically.

CD44s expression in human colon carcinomas influences growth of liver metastases

CD44 is a family of cell-surface adhesion molecules which exist in several isoforms arising from mRNA alternative. Malignant transformation of colonic mucosa is associated with alterations in CD44 expression, which result in up-regulation of high-molecular-weight CD44 isoforms and down-regulation of CD44s. We have demonstrated that stable transfection of CD44s into colon-carcinoma cell lines reduces their tumorigenicity. To understand the influence of CD44s expression on the metastatic potential of human colon carcinomas, we measured the ability of several different CD44s-transfected colon carcinomas to establish experimental liver metastases following splenic inoculation in mice. We observed that introduction of CD44s into 2 different human colon carcinoma cell lines, HT29 and KM12C6, resulted in reduced growth of liver metastases by as much as 75%. To explore the relationship between hyaluronate adhesion and metastasis, we transfected HT29 cells with cDNA encoding a mutant CD44s that does not bind to hyaluronate. HT29 transfectants expressing this mutant CD44s demonstrate an 84% reduction in growth of liver metastases, despite minimal binding to hyaluronate by the mutant CD44s. In concert, these results indicate that CD44s down-regulation, which occurs with malignant transformation of colonic mucosa, is associated with enhanced growth of experimental liver metastases. Consequently, the functional consequences of CD44s down-regulation in colon carcinomas may be just as significant as the consequences of up-regulation of other CD44 isoforms.

Expression of CD44 adhesion molecules in nonpapillary renal cell carcinoma and normal kidneys

OBJECTIVES

To analyze the relationship between the alterations in the expression of the CD44 gene in nonpapillary renal cell carcinoma (RCC) and several clinicopathologic factors.

METHODS

The expression of the CD44 gene in 10 human RCC cell lines, 60 nonpapillary RCC tumor samples, and 15 normal kidney samples was investigated by reverse-transcription polymerase chain reaction (RT-PCR) using a set of primers capable of amplifying all CD44 variant isoforms. The results were analyzed with respect to several clinicopathologic factors.

RESULTS

Nine of the 10 human RCC cell lines predominantly expressed the standard CD44 isoform (CD44s); CD44v10 was the major isoform in the 10th RCC cell line. The 15 normal kidney samples revealed the identical CD44 gene expression pattern; that is, CD44s, CD44v8-10, and CD44v10 were detectable in normal kidneys, and among them, CD44s was expressed most dominantly. In the 60 nonpapillary RCC samples, CD44s, CD44v8-10, and CD44v10 were the major isoforms in 46 (77%), 11 (18%), and 3 (5%) cases, respectively. Furthermore, the incidence of the predominant expression of CD44v8-10 in high-stage RCC was significantly higher than that in low-stage RCC. CD44s was more frequently expressed as a major isoform in clear cell RCC than in other histologic types of RCC.

CONCLUSIONS

The results of this study show that the alternative splicing pattern of CD44 gene in RCC is different in each histologic type of RCC and suggest that CD44v8-10 upregulation in the progression of nonpapillary RCC is important.

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.

Highly specific and sensitive detection of malignancy in urine samples from patients with urothelial cancer by CD44v8-10/CD44v10 competitive RT-PCR

CD44 is a widely expressed cell surface adhesion molecule in which various isoforms arise from alternative RNA splicing mechanism. Overexpression of specific CD44 splice variant, i.e., CD44v8-10, has been found in several human malignancies and is considered to be associated with tumor progression and metastasis. We have demonstrated a novel molecular approach, CD44v8-10/CD44v10 competitive reverse transcription-polymerase chain reaction (CC-RT-PCR) for the detection of cancer cells overexpressing CD44v8-10 by the measurement of the transcriptional level of CD44v8-10 relative to that of CD44v10 (v8-10/v10 ratio). In this study, we initially examined the expression of CD44 splice variants in human urothelial cancers and their adjacent normal urinary tissues by RT-PCR. Any CD44 variant isoforms were barely detectable in normal urinary tissues, whereas CD44v8-10 was predominantly expressed in 23 of the 30 (77%) urothelial cancer specimens. We then applied CC-RT-PCR to spontaneously voided urine samples from patients with 80 urothelial cancer and 50 various benign urologic diseases. The CC-RT-PCR analysis revealed that all of the samples associated with benign diseases presented a predominant expression of the CD44v10 transcript (the v8-10/v10 ratios = 0.00-0.87), whereas 62 of the 80 samples associated with urothelial cancers mostly expressed the CD44v8-10 transcript (the v8-10/v10 ratios > 1.00). In addition, the positivity rate obtained by the CC-RT-PCR analysis was high regardless of the pathological grade of the urothelial cancers, although the sensitivity of the cytological examination declined with decreasing tumor grade. Our findings suggest strongly that CC-RT-PCR is a non-invasive useful tool for the diagnosis of urine samples from patients with urothelial cancer.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Our results suggest that the E/H ratio is a useful indicator of prognosis in gastric and colorectal carcinoma.

Increased expression of CD44v6 mRNA significantly correlates with distant metastasis and poor prognosis in gastric cancer

Expression of CD44 and its variants is associated with clinically aggressive behavior of some human cancers. The present study was undertaken to determine the expression level of these CD44 mRNAs in relation to the clinicopathologic features and prognosis of gastric cancer. Using reverse transcription polymerase chain reaction followed by Southern blotting, we examined the expression of the standard and variant (v6 and v9) forms of CD44 mRNA in 73 cases of gastric cancer. We determined the ratio of mRNA expression in cancer tissue to normal tissue (T/N ratio) and evaluated the correlations of the ratio with clinico-pathologic features, tumor progression and prognosis. The expression level of the standard form of CD44 (CD44s) mRNA correlated with peritoneal dissemination only, and that of CD44v9 mRNA did not significantly correlate with any clinicopathologic factor. The expression level of CD44v6 mRNA was significantly higher in patients with lymph node metastasis and liver metastasis. In 48 curatively resected patients, the expression level of CD44v6 mRNA correlated with the site of recurrence. Furthermore, there was a significant survival advantage in patients with low expression of CD44v6 mRNA compared with those with high expression. The level of CD44v6 mRNA expression may be a potential prognostic indicator and may be useful as a predictor for distant metastasis and recurrence in patients with gastric cancer.

CD44 variant isoform expression and breast cancer prognosis

We examined the expression of CD44 isoforms in samples of breast cancer tissues from 95 patients by reverse transcription-polymerase chain reaction and immunohistochemistry, and tried to correlate the results with survival period. At the RNA level, expression of exon v2 was observed in 33 (35%) and that of v6 in 69 (73%) of the 95 specimens. Patients with CD44v2 mRNA expression had significantly shorter survival times than those with v2-negative tumors (P = 0.05), but there was only a weak correlation, if any, between v6 mRNA expression and overall survival (P = 0.06). Tumor tissue from 22 (23%) and 72 (76%) patients showed positive immunoreactivity with monoclonal antibody (mAb) M23.6.1. (CD44v2) and mAb 2F10 (CD44v6), respectively. Immunohistochemical evidence of CD44v2 peptide expression correlated with overall survival (P = 0.02), but there was no such association with CD44v6 expression in these tumors (P = 0.67). There were significant correlations between v2 immunoreactivity and higher histological grade and lower levels of estrogen and progesterone receptor. There was no significant correlation between v6 immunoreactivity and such clinicopathological characteristics. Although the expression of v2 was significantly associated with reduced overall survival, it was not an independent prognostic factor because it also correlated with progesterone receptor status. These findings suggest that v2 isoform expression might have more value than v6 expression for clinical use.

Molecular detection of cancer cells by competitive reverse transcription-polymerase chain reaction analysis of specific CD44 variant RNAs

BACKGROUND

CD44 is a cell surface glycoprotein implicated in such diverse biologic processes as lymphocyte activation and homing, extracellular matrix adhesion, and cellular migration. Primary transcripts of the CD44 gene can be alternatively spliced to produce a variety of messenger RNA (mRNA) species. The standard form of CD44 mRNA contains sequences from at least 20 genomic exons; variant mRNAs contain sequences from one or more additional exons (v1-10). Predominant expression of a specific CD44 variant, i.e., CD44v8-10, in several human carcinomas has been described previously. In this study, we developed a novel molecular approach for detecting cancer cells that overexpress CD44v8-10 mRNA.

METHODS

After finding that CD44v8-10 was predominantly expressed in non-small-cell lung and bladder carcinomas and that CD44v10 was predominantly expressed in leukocytes, we developed a competitive reverse transcription-polymerase chain reaction assay (CC-RT-PCR) that allows quantification of the relative expression of these two mRNA species in clinical specimens (i.e., determination of a v8-10/v10 ratio). CC-RT-PCR analysis was applied to pleural effusion specimens from patients with benign or malignant lung diseases as well as to spontaneously voided urine samples from patients with benign or malignant urologic diseases.

RESULTS

Fifty two of 54 samples from patients with benign diseases expressed CD44v10 predominantly (v8-10/v10 ratio < or = 0.65), whereas 46 of 61 samples from patients with malignant diseases expressed CD44v8-10 predominantly (v8-10/v10 ratio > 1.00) (two-sided P < .001). CC-RT-PCR detected predominant expression of CD44v8-10 in cytologically negative samples from 11 patients who were later diagnosed with malignant disease.

CONCLUSIONS

CC-RT-PCR analysis of CD44v8-10 expression could be an important adjunct to cytologic examination in cancer diagnosis, especially in detecting exfoliated cancer cells in pleural effusions and urine.

The standard isoform of CD44 is preferentially expressed in atypical papillomas and carcinomas of the choroid plexus

Isoforms of the CD44 adhesion molecule have been assigned a pivotal role in tumor invasion and metastasis. CD44 splice variants may be selectively expressed in various normal and neoplastic tissues. We investigated immunohistochemically the presence of the standard (H) and two variant (v3, v6) isoforms of the CD44 molecule in a series comprising 13 choroid plexus papillomas (WHO grade I) and 8 carcinomas (WHO grade III). In the papilloma group, 5 tumors showed variable cellular pleomorphism and foci of infiltrative growth, and were tentatively classified as atypical papillomas. Autopsy specimens of normal pediatric and adult choroid plexus were used as control. Western-blot analysis of CD44H was carried out on 4 carcinomas, 1 papilloma and on normal choroid plexus. The proliferation rate was assessed by MIB-1 immunoreactivity. The normal choroid plexuses and 9 papillomas were negative for the standard as well as the variant CD44 molecules investigated. Four atypical papillomas and 5 carcinomas expressed CD44H. CD44v3 and CD44v6 were only detected in one of the atypical papillomas also positive for CD44H. These data indicate that CD44H is preferentially expressed on atypical papillomas and carcinomas and may correlate with the infiltrative growth of these tumors.