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

TDP43 promotes stemness of breast cancer stem cells through CD44 variant splicing isoforms

Alternative splicing (AS) is a promising clinical target for cancer treatment at the post-transcriptional level. We previously identified a unique AS profile in triple-negative breast cancer (TNBC), which is regulated by the splicing regulator TAR DNA-binding protein-43 (TDP43), thus indicating the crucial role of TDP43 in heterogeneous TNBC. Cluster of differentiation 44 (CD44), a widely recognized marker for breast cancer stem cells (BCSCs), is extensively spliced into CD44 variant AS isoforms (CD44v) during the development of breast cancer. At present, however, the regulatory mechanism of CD44v is not fully understood. In the current study, we found that loss of TDP43 inhibits BCSC stemness by reducing the abundance of CD44v. In addition, serine-arginine-rich splicing factor 3 (SRSF3), another splicing factor and partner of TDP43, acts as an upstream regulator of TDP43 to maintain CD44v isoforms and thereafter BCSC stemness. Mechanistically, SRSF3 stabilizes the mRNA of TDP43 by inhibiting nonsense-mediated decay (NMD). These findings illustrate the important role of complicated regulatory networks formed by splicing factors in TNBC progression, thus providing potential therapeutic targets from an AS perspective.

Potential of Stem Cells and CART as a Potential Polytherapy for Small Cell Lung Cancer

Despite the increasing urgency of the problem of treating small cell lung cancer (SCLC), information on the causes of its development is fragmentary. There is no complete understanding of the features of antitumor immunity and the role of the microenvironment in the development of SCLC resistance. This impedes the development of new methods for the diagnosis and treatment of SCLC. Lung cancer and chronic obstructive pulmonary disease (COPD) have common pathogenetic factors. COPD is a risk factor for lung cancer including SCLC. Therefore, the search for effective approaches to prevention, diagnosis, and treatment of SCLC in patients with COPD is an urgent task. This review provides information on the etiology and pathogenesis of SCLC, analyses the effectiveness of current treatment options, and critically evaluates the potential of chimeric antigen receptor T cells therapy (CART therapy) in SCLC. Moreover, we discuss potential links between lung cancer and COPD and the role of endothelium in the development of COPD. Finally, we propose a new approach for increasing the efficacy of CART therapy in SCLC.

CD44 variant-dependent regulation of redox balance in EGFR mutation-positive non-small cell lung cancer: A target for treatment

OBJECTIVES

The regulation of redox balance in cancer cells is an important factor in tumor development and chemoresistance, with oncogene activation having been shown to induce the generation of reactive oxygen species (ROS). Activating mutations of the epidermal growth factor receptor gene (EGFR) are oncogenic drivers in non-small cell lung cancer (NSCLC), but it has remained unknown whether ligand-independent EGFR signaling conferred by EGFR mutation triggers ROS generation in NSCLC cells.

MATERIALS AND METHODS

HEK293T cells were transfected with an expression vector for mutant EGFR. The expression of CD44 variant (CD44v) isoforms in NSCLC cell lines was evaluated by flow cytometry. Cells were depleted of CD44v by RNA interference and assayed for ROS and glutathione (GSH) levels. The effect of CD44v on cisplatin sensitivity was evaluated in vitro with the MTS assay.

RESULTS

EGFR signaling due to EGFR mutation increased ROS levels in transfected HEK293T cells. The expression of CD44v isoforms was found to be inversely correlated with basal ROS levels in EGFR mutation-positive NSCLC cell lines. Knockdown of CD44v induced depletion of intracellular GSH and increased ROS levels in EGFR-mutated NSCLC cells that express CD44v at a high level (CD44v^high). In addition, depletion of GSH by treatment with buthionine-[S, R]-sulfoximine induced marked accumulation of ROS and enhanced the cytotoxicity of cisplatin in CD44v^highEGFR-mutated NSCLC cells but not in corresponding CD44v^low cells. This enhancement of cisplatin cytotoxicity by GSH depletion was prevented by treatment with the antioxidant N-acetyl-l-cysteine. Knockdown of CD44v also enhanced cisplatin cytotoxicity in CD44v^highEGFR mutation-positive NSCLC cells but not in CD44v^low cells.

CONCLUSION

Our results thus implicate CD44v in redox adaptation and as a potential target for treatment in CD44v^highEGFR-mutated NSCLC cells.

Phase I study of salazosulfapyridine in combination with cisplatin and pemetrexed for advanced non-small-cell lung cancer

Spliced variant isoforms of CD44 (CD44v) are a marker of cancer stem cells in solid tumors. They stabilize the xCT subunit of the transporter system xc(–) and thereby promote synthesis of the antioxidant glutathione. Salazosulfapyridine (SASP) is an inhibitor of xCT and suppresses the proliferation of CD44v‐positive cancer cells. Chemotherapy‐naïve patients with advanced non‐squamous non‐small‐cell lung cancer were enrolled in a dose‐escalation study (standard 3 + 3 design) of SASP in combination with cisplatin and pemetrexed. The primary end‐point was the percentage of patients who experience dose‐limiting toxicity. Fifteen patients were enrolled in the study. Dose‐limiting toxicity was observed in one of six patients at a SASP dose of 1.5 g/day (elevation of aspartate and alanine aminotransferase levels, each of grade 3), two of five patients at 3 g/day (hypotension or pneumonitis, each of grade 3), and two of three patients at 4.5 g/day (anorexia of grade 3). The maximum tolerated dose was thus 3 g/day, and the recommended dose was 1.5 g/day. The overall response rate was 26.7% and median progression‐free survival was 11.7 months, much longer than that for cisplatin–pemetrexed alone in previous studies. Exposure to SASP varied markedly among individuals according to ABCG2 and NAT2 genotypes. The serum concentration of free CD44v protein was increased after the first cycle of treatment, possibly reflecting death of cancer stem cells. Salazosulfapyridine was thus given safely in combination with cisplatin–pemetrexed, with the addition of SASP tending to prolong progression‐free survival. This trial is registered in the UMIN Clinical Trials Registry as UMIN000017854.

Inflammatory mediator ultra-low-molecular-weight hyaluronan triggers necrosis of B-precursor leukemia cells with high surface CD44 expression

Acute lymphoblastic leukemia (ALL) with mixed lineage leukemia (MLL) gene rearrangements (MLL+ALL) has a dismal prognosis and is characterized by high surface CD44 expression. Known that CD44 has the specific binding sites for a natural ligand hyaluronan (HA), we investigated biological effects of HA with different molecular sizes on MLL+ALL cell lines, and found that the addition of ultra-low-molecular-weight (ULMW)-HA strongly suppressed their thymidine uptakes. The MLL+ALL cell line lacking surface CD44 expression established by genome editing showed no suppression of thymidine uptake. Surface CD44-high B-precursor ALL cell lines other than MLL+, but not T-ALL cell lines, were also suppressed in their thymidine uptakes. The inhibition of thymidine uptakes was because of induction of cell death, but dead cells lacked features of apoptosis on cytospin smears and flow cytometric analysis. The cell death was neither blocked by pan-caspase inhibitor nor autophagy inhibitor, but was completely blocked by necrosis inhibitor necrostatin-1. Necrotic cell death was further supported by a marked release of a high-mobility protein group B1 and morphological changes on transmission electron microscopy. Elevation of intracellular reactive oxygen species production suggested a role for inducing this necrotic cell death. ULMW-HA-triggered cell death was similarly demonstrated in surface CD44-high primary B-precursor leukemia cells. Assuming that ULMW-HA is abundantly secreted at the site of infection and inflammation, this study sheds light on understanding the mechanism of a transient inflammation-associated remission of leukemia. Further, the CD44-targeting may become an effective approach in future for the treatment of refractory B-precursor ALL by its capability of predominantly eradicating CD44-high leukemia-initiating cells.

Comparable roles of CD44v8-10 and CD44s in the development of bone metastases in a mouse model

Cluster of differentiation (CD)44 has been implicated in cancer metastasis to bone. Clinical and experimental studies have suggested that the standard isoform of CD44 (CD44s) and the variant isoform of CD44 (CD44v) enhance metastasis. The present study examined the differential roles of CD44s and CD44v, particularly CD44v8-10, in the development of bone metastases. For this purpose, MDA-MB-231 human breast cancer cells and A549 human lung cancer cells were stably transduced with epithelial splicing regulatory protein 1 (ESRP1), which regulates the alternative splicing of several genes, including CD44. The introduction of ESRP1 induced a splicing switch from CD44s to CD44v, particularly to CD44v8-10, while the total amount of CD44 was rarely affected. However, ESRP1 did not significantly affect cell proliferation, migration, invasion or tumor sphere formation in vitro. Furthermore, ESRP1 did not cause significant differences in the development of bone metastases in a mouse model. As an alternative approach, cancer cells transduced with the CD44v8-10 gene were also established. The overexpression of CD44v8-10 in MCF-7 human breast cancer cells, which rarely express any isoform of CD44, promoted cell migration and sphere formation, whereas the overexpression of CD44v8-10 in MDA-MB-231 cells, which endogenously express high levels of CD44s, did not exert these effects. The results of the present study collectively suggest that the ability of CD44v8-10 to promote tumor aggressiveness and bone metastases is similar to that of CD44s. CD44v8-10 and CD44s may represent potential therapeutic targets for the treatment of bone metastases.

CD82 suppresses CD44 alternative splicing-dependent melanoma metastasis by mediating U2AF2 ubiquitination and degradation

Melanoma is one of the most lethal forms of skin cancer because of its early metastatic spread. The variant form of CD44 (CD44v), a cell surface glycoprotein, is highly expressed on metastatic melanoma. The mechanisms of regulation of CD44 alternative splicing in melanoma and its pathogenic contributions are so far poorly understood. Here, we investigated the expression level of CD44 in a large set of melanocytic lesions at different stages. We found that the expression of CD44v8-10 and a splicing factor, U2AF2, is significantly increased during melanoma progression, whereas CD82/KAI1, a tetraspanin family of tumor suppressor, is reduced in metastatic melanoma. CD44v8-10 and U2AF2 expression levels, which are negatively correlated with CD82 levels, are markedly elevated in primary melanoma compared with dysplastic nevi and further increased in metastatic melanoma. We also showed that patients with higher CD44v8-10 and U2AF2 expression levels tended to have shorter survival. By using both in vivo and in vitro assays, we demonstrated that CD82 inhibits the production of CD44v8-10 on melanoma. Mechanistically, U2AF2 is a downstream target of CD82 and in malignant melanoma facilitates CD44v8-10 alternative splicing. U2AF2-mediated CD44 isoform switch is required for melanoma migration in vitro and lung and liver metastasis in vivo. Notably, overexpression of CD82 suppresses U2AF2 activity by inducing U2AF2 ubiquitination. In addition, our data suggested that enhancement of melanoma migration by U2AF2-dependent CD44v8-10 splicing is mediated by Src/focal adhesion kinase/RhoA activation and formation of stress fibers, as well as CD44-E-selectin binding reinforcement. These findings uncovered a hitherto unappreciated function of CD82 in severing the linkage between U2AF2-mediated CD44 alternative splicing and cancer aggressiveness, with potential prognostic and therapeutic implications in melanoma.

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.

Analysis of multiple markers for cancer stem-like cells in human thyroid carcinoma cell lines

Cancer stem-like cells (CSCs) play important roles in cancer initiation and progression. CSCs have been isolated using several markers, but those for thyroid CSCs remain to be confirmed. We therefore conducted a comprehensive search for thyroid CSC markers. Expression of nine cell surface markers (CD13, CD15, CD24, CD44, CD90, CD117, CD133, CD166, and CD326) and aldehyde dehydrogenase (ALDH) activity, which are CSC markers in various solid cancers, and the ability to form spheres in vitro and tumors in vivo were investigated using eight thyroid cancer cell lines (FRO, KTC1/2/3, TPC1, WRO, ACT1, and 8505C). Among these, four cell lines (FRO, KTC3, ACT1, and 8505C) possessed the both abilities; however, common markers indicative of CSCs were not observed. The pattern of ability to form spheres was completely matched to that of tumor formation, suggesting that our sphere assay is valuable for assessment of tumor-forming ability. Next, the cells were sorted using these markers and subjected to the sphere assay. In three cell lines (FRO, KTC3, and ACT1), ALDH(pos) cells showed higher sphere forming ability than ALDH(neg) cells but not in other cells. CD326(hi) also appeared to be a candidate marker only in FRO cells. However, these subpopulations did not follow a classical hierarchical model because ALDH(neg) and CD326(low) fractions also generated ALDH(pos) and CD326(hi) cells, respectively. These data suggest that ALDH activity is probably a major candidate marker to enrich thyroid CSCs but not universal; other markers such as CD326 that regulate different CSC properties may exist.

Stress-response protein RBM3 attenuates the stem-like properties of prostate cancer cells by interfering with CD44 variant splicing

Stress-response pathways play an important role in cancer. The cold-inducible RNA-binding protein RBM3 is upregulated in several types of cancer, including prostate cancer, but its pathogenic contributions are undetermined. RBM3 is expressed at low basal levels in human fetal prostate or in CD133(+) prostate epithelial cells (PrEC), compared with the adult prostate or CD133-PrEC, and RBM3 is downregulated in cells cultured in soft agar or exposed to stress. Notably, RBM3 overexpression in prostate cancer cells attenuated their stem cell-like properties in vitro as well as their tumorigenic potential in vivo. Interestingly, either overexpressing RBM3 or culturing cells at 32°C suppressed RNA splicing of the CD44 variant v8-v10 and increased expression of the standard CD44 (CD44s) isoform. Conversely, silencing RBM3 or culturing cells in soft agar (under conditions that enrich for stem cell-like cells) increased the ratio of CD44v8-v10 to CD44s mRNA. Mechanistic investigations showed that elevating CD44v8-v10 interfered with MMP9-mediated cleavage of CD44s and suppressed expression of cyclin D1, whereas siRNA-mediated silencing of CD44v8-v10 impaired the ability of prostate cancer cells to form colonies in soft agar. Together, these findings suggested that RBM3 contributed to stem cell-like character in prostate cancer by inhibiting CD44v8-v10 splicing. Our work uncovers a hitherto unappreciated role of RBM3 in linking stress-regulated RNA splicing to tumorigenesis, with potential prognostic and therapeutic implications in prostate cancer.

Cancer stem-like cell marker CD44 promotes bone metastases by enhancing tumorigenicity, cell motility, and hyaluronan production

CD44, an adhesion molecule that binds to the extracellular matrix, primarily to hyaluronan (HA), has been implicated in cancer cell migration, invasion, and metastasis. CD44 has also recently been recognized as a marker for stem cells of several types of cancer. However, the roles of CD44 in the development of bone metastasis are unclear. Here, we addressed this issue by using bone metastatic cancer cell lines, in which CD44 was stably knocked down. Tumor sphere formation and cell migration and invasion were significantly inhibited by CD44 knockdown. Furthermore, the downregulation of CD44 markedly suppressed tumorigenicity and bone metastases in nude mice. Of note, the number of osteoclasts decreased in the bone metastases. Microarray analysis revealed that the expression of HA synthase 2 was downregulated in CD44-knockdown cells. The localization of HA in the bone metastatic tumors was also markedly reduced. We then examined the roles of CD44-HA interaction in bone metastasis using 4-methylumbelliferone (4-MU), an inhibitor of HA synthesis. 4-MU decreased tumor sphere and osteoclast-like cell formation in vitro. Moreover, 4-MU inhibited bone metastases in vivo with reduced number of osteoclasts. These results collectively suggest that CD44 expression in cancer cells promotes bone metastases by enhancing tumorigenicity, cell migration and invasion, and HA production. Our results also suggest the possible involvement of CD44-expressing cancer stem cells in the development of bone metastases through interaction with HA. CD44-HA interaction could be a potential target for therapeutic intervention for bone metastases.

Anti-tumor effect against human cancer xenografts by a fully human monoclonal antibody to a variant 8-epitope of CD44R1 expressed on cancer stem cells

Background

CD44 is a major cellular receptor for hyaluronic acids. The stem structure of CD44 encoded by ten normal exons can be enlarged by ten variant exons (v1-v10) by alternative splicing. We have succeeded in preparing MV5 fully human IgM and its class-switched GV5 IgG monoclonal antibody (mAb) recognizing the extracellular domain of a CD44R1 isoform that contains the inserted region coded by variant (v8, v9 and v10) exons and is expressed on the surface of various human epithelial cancer cells.

Methods and Principal Findings

We demonstrated the growth inhibition of human cancer xenografts by a GV5 IgG mAb reshaped from an MV5 IgM. The epitope recognized by MV5 and GV5 was identified to a v8-coding region by the analysis of mAb binding to various recombinant CD44 proteins by enzyme-linked immunosorbent assay. GV5 showed preferential reactivity against various malignant human cells versus normal human cells assessed by flow cytometry and immunohistological analysis. When ME180 human uterine cervix carcinoma cells were subcutaneously inoculated to athymic mice with GV5, significant inhibition of tumor formation was observed. Furthermore, intraperitoneal injections of GV5markedly inhibited the growth of visible established tumors from HSC-3 human larynx carcinoma cells that had been subcutaneously transplanted one week before the first treatment with GV5. From in vitro experiments, antibody-dependent cellular cytotoxicity and internalization of CD44R1 seemed to be possible mechanisms for in vivo anti-tumor activity by GV5.

Conclusions

CD44R1 is an excellent molecular target for mAb therapy of cancer, possibly superior to molecules targeted by existing therapeutic mAb, such as Trastuzumab and Cetuximab recognizing human epidermal growth factor receptor family.

CD44 expression in oro-pharyngeal carcinoma tissues and cell lines

Expression of CD44, a transmembrane hyaluronan-binding glycoprotein, is variably considered to have prognostic significance for different cancers, including oral squamous cell carcinoma. Although unclear at present, tissue-specific expression of particular isoforms of CD44 might underlie the different outcomes in currently available studies. We mined public transcriptomics databases for gene expression data on CD44, and analyzed normal, immortalized and tumour-derived human cell lines for splice variants of CD44 at both the transcript and protein levels. Bioinformatics readouts, from a total of more than 15,000 analyses, implied an increased CD44 expression in head and neck cancer, including increased expression levels relative to many normal and tumor tissue types. Also, meta-analysis of over 260 cell lines and over 4,000 tissue specimens of diverse origins indicated lower CD44 expression levels in cell lines compared to tissue. With minor exceptions, reverse transcribed polymerase chain reaction identified expression of the four main isoforms of CD44 in normal oral keratinocytes, transformed lines termed DT and HaCaT, and a series of paired primary and metastasis-derived cell lines from oral or pharyngeal carcinomas termed HN4/HN12, HN22/HN8 and HN30/HN31. Immunocytochemistry, Western blotting and flow cytometric assessments all confirmed the isoform expression pattern at the protein level. Overall, bioinformatic processing of large numbers of global gene expression analyses demonstrated elevated CD44 expression in head and neck cancer relative to other cancer types, and that the application of standard cell culture protocols might decrease CD44 expression. Additionally, the results show that the many variant CD44 exons are not fundamentally deregulated in a diverse range of cultured normal and transformed keratinocyte lines.

Significance of survivin and Bcl-2 homologous antagonist/killer mRNA in detection of bone metastasis in patients with breast cancer

The aim of this study was to assess the diagnostic value of survivin and Bcl-2 homologous antagonist/killer (Bak) mRNA in the detection of patients with bone metastatic breast cancer. This study included 92 patients with breast carcinoma (54 non-metastatic and 38 bone metastatic) and 31 patients with benign breast lesions. Survivin in cell lysates was measured by ELISA while tissue Bak mRNA was detected by RT-PCR. Survivin was significantly increased in bone metastatic breast cancer patients compared to non-metastatic cases or benign ones. Bak mRNA was markedly decreased in bone metastatic patients compared to non-metastatic ones, while significant expression of Bak mRNA was observed in bone metastatic cases compared to benign patients. High survivin level was associated with high grade, late stages and lymph node involvement, whereas low Bak mRNA was associated with late stages. Our data indicate that survivin and Bak mRNA were considerable markers for the identification of breast cancer patients with bone metastasis.

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.

Tumor necrosis factor-alpha regulates transforming growth factor-beta-dependent epithelial-mesenchymal transition by promoting hyaluronan-CD44-moesin interaction

Aberrant epithelial-mesenchymal transition (EMT) is involved in development of fibrotic disorders and cancer invasion. Alterations of cell-extracellular matrix interaction also contribute to those pathological conditions. However, the functional interplay between EMT and cell-extracellular matrix interactions remains poorly understood. We now show that the inflammatory mediator tumor necrosis factor-alpha (TNF-alpha) induces the formation of fibrotic foci by cultured retinal pigment epithelial cells through activation of transforming growth factor-beta (TGF-beta) signaling in a manner dependent on hyaluronan-CD44-moesin interaction. TNF-alpha promoted CD44 expression and moesin phosphorylation by protein kinase C, leading to the pericellular interaction of hyaluronan and CD44. Formation of the hyaluronan-CD44-moesin complex resulted in both cell-cell dissociation and increased cellular motility through actin remodeling. Furthermore, this complex was found to be associated with TGF-beta receptor II and clathrin at actin microdomains, leading to activation of TGF-beta signaling. We established an in vivo model of TNF-alpha-induced fibrosis in the mouse eye, and such ocular fibrosis was attenuated in CD44-null mice. The production of hyaluronan and its interaction with CD44, thus, play an essential role in TNF-alpha-induced EMT and are potential therapeutic targets in fibrotic disorders.

CCK(2) receptor splice variant with intron 4 retention in human gastrointestinal and lung tumours

The wild-type cholecystokinin type 2 (CCK₂) receptor is expressed in many gastrointestinal and lung tumours. A splice variant of the CCK₂ receptor with retention of intron 4 (CCK₂Ri4sv) showing constitutive activity associated with increased tumour growth was described in few colorectal, pancreatic and gastric cancers. Given the potential functional and clinical importance of this spliceoform, its occurrence was quantitatively characterized in a broad collection of 81 gastrointestinal and lung tumours, including insulinomas, ileal carcinoids, gastrointestinal stromal tumours (GIST), gastric, colorectal and pancreatic ductal adenocarcinomas, cholangiocellular and hepatocellular carcinomas, small cell lung cancers (SCLC), non-SCLC (nSCLC) and bronchopulmonary carcinoids, as well as 21 samples of corresponding normal tissues. These samples were assessed for transcript expression of total CCK₂ receptor, wild-type CCK₂ receptor and CCK₂Ri4sv with end-point and real-time RT-PCR, and for total CCK₂ receptor protein expression on the basis of receptor binding with in vitro receptor autoradiography. Wild-type CCK₂ receptor transcripts were found in the vast majority of tumours and normal tissues. CCK₂Ri4sv mRNA expression was present predominantly in insulinomas (incidence 100%), GIST (100%) and SCLC (67%), but rarely in pancreatic, colorectal and gastric carcinomas and nSCLC. It was not found in wild-type CCK₂ receptor negative tumours or any normal tissues tested. CCK₂Ri4sv transcript levels in individual tumours were low, ranging from 0.02% to 0.14% of total CCK₂ receptor transcripts. In conclusion, the CCK₂Ri4sv is a marker of specific gastrointestinal and lung tumours. With its high selectivity for and high incidence in SCLC and GIST, it may represent an attractive clinical target.

Alternative splicing of pre-mRNA in cancer: focus on G protein-coupled peptide hormone receptors

Through alternative splicing, multiple different transcripts can be generated from a single gene. Alternative splicing represents an important molecular mechanism of gene regulation in physiological processes such as developmental programming as well as in disease. In cancer, splicing is significantly altered. Tumors express a different collection of alternative spliceoforms than normal tissues. Many tumor-associated splice variants arise from genes with an established role in carcinogenesis or tumor progression, and their functions can be oncogenic. This raises the possibility that products of alternative splicing play a pathogenic role in cancer. Moreover, cancer-associated spliceoforms represent potential diagnostic biomarkers and therapeutic targets. G protein-coupled peptide hormone receptors provide a good illustration of alternative splicing in cancer. The wild-type forms of these receptors have long been known to be expressed in cancer and to modulate tumor cell functions. They are also recognized as attractive clinical targets. Recently, splice variants of these receptors have been increasingly identified in various types of cancer. In particular, alternative cholecystokinin type 2, secretin, and growth hormone-releasing hormone receptor spliceoforms are expressed in tumors. Peptide hormone receptor splice variants can fundamentally differ from their wild-type receptor counterparts in pharmacological and functional characteristics, in their distribution in normal and malignant tissues, and in their potential use for clinical applications.

Detection of circulating tumor cells in bladder cancer patients

The methods employed for the detection of circulating bladder cancer cells (CBCs) and their use as a molecular staging tool in clinical settings are thoroughly reviewed. CBC isolation and enrichment methods are discussed according to their advantages and pitfalls along with the clinical data of PCR-based techniques used for CBC detection. In addition, we review the specificity of molecular markers that have been proposed so far for CBC identification, and we comment on the controversial clinical data, proposing laboratory approaches which may improve the clinical significance of CBC detection in bladder cancer.

Comparison of CD44 and cytokeratin 20 mRNA in voided urine samples as diagnostic tools for bladder cancer

OBJECTIVES

We evaluated the diagnostic efficacy of urinary CD44 and cytokeratin 20 (CK20) mRNA in comparison with voided urine cytology (VUC) for the detection of bladder cancer.

DESIGN AND METHODS

A total of 136 Egyptian patients provided a single voided urine sample for CD44, CK20 mRNA and VUC before cystoscopy. Of the 136 cases, 111 were histologically diagnosed as bladder cancer whereas the remaining 25 had benign urological disorders. A group of 20 healthy volunteers was also included in this study. Voided urine was centrifuged and the urine sediment was used for cytology, estimation of CD44 by ELISA and RNA extraction. CK20 mRNA was detected by conventional RT-PCR and quantitative real-time RT-PCR.

RESULTS

The best cutoff values for CD44 and relative CK20 mRNA detected by real-time RT-PCR were calculated by receiver operating characteristic curve. The positivity rates and the mean ranks for CD44 and CK20 mRNA showed significant difference among the three investigated groups (p=0.001). Quantitative real-time RT-PCR results were comparable to conventional RT-PCR for the detection of CK20 mRNA. The positivity rate of CD44 was significantly associated with schistosomiasis and urine cytology. The overall sensitivity and specificity were 52.3% and 88.9% for VUC, 63.1% and 88.9% for CD44, and 82.0% and 97.8% for CK20 mRNA. Combined sensitivity of VUC with CD44 and CK20 mRNA together (95.5%) was higher than either the combined sensitivity of VUC with CD44 (78.4%) or with CK20 mRNA (91.0%) or than that of the biomarker alone.

CONCLUSION

Urinary CD44 and CK20 mRNA had higher sensitivities compared to VUC. However, when the diagnostic efficacy was considered, CK20 mRNA by either conventional RT-PCR or real-time RT-PCR had the highest sensitivity and specificity compared to CD44 and VUC.

The evolving role of interventional pulmonary in the interdisciplinary approach to the staging and management of lung cancer. Part III: diagnosis and management of malignant pleural effusions

The diagnosis and management of a malignant pleural effusion can be one of the most vexing problems faced by physicians and their patients. Lung cancer is the most common primary tumor of origin with a prognosis that is limited, but variable and correlated with performance status (PS). Therefore, with a poor PS and known advanced lung cancer, establishing whether or not an effusion is malignant might not be necessary. Conversely, identifiable subsets of patients will have a much better survival, and establishing a definitive diagnosis could be of critical importance. In the great majority of cases, a diagnosis can be determined by serial thoracenteses with or without closed pleural biopsy. However, thoracoscopy is increasingly being utilized and can expedite the workup by obviating the need for repeated thoracenteses and/or closed pleural biopsy, while in the same setting providing definitive palliative treatment. Although studies comparing diagnostic and treatment strategies are limited, we will present the available data with the intention of providing the practicing oncologist with a practical strategy for the diagnosis and management of malignant pleural effusions due to lung cancer. The interventional pulmonologist can play an important role from diagnosis to palliation, greatly facilitating the care of patients with malignant pleural effusions.

Quantification of gene expression in urinary sediment for the study of renal diseases

Urinalysis has been used extensively in clinical practice to aid in the diagnosis of various renal diseases. With the advances in technology of molecular biology, gene expression and proteomic studies are now possible for urinary sediment. In this review article, we focus on the quantification of messenger RNA expression in urinary sediment by reverse-transcription and real-time quantitative polymerase chain reaction. Recently, this technique has been explored for three potential applications: (i) distinguishing the different causes of kidney disease; (ii) assessment of kidney disease activity, progression and response to therapy; and (iii) as a tool to study the pathogenesis. Although the method is simple and non-invasive, it requires further research to define the role in routine clinical practice. At this moment, the technique should only be considered experimental albeit promising.

MN/CA9: a potential gene marker for detection of malignant cells in effusions

Many cancers cause malignant effusions. The presence of malignant cells in effusions has implications in diagnosis, tumour staging and prognosis. The detection of malignant cells currently presents a challenge for cytopathologists. New adjunctive methods are needed. Although the effusions provide excellent materials for molecular assay, the available molecular markers are extremely limited, which hinders its clinical application. MN/CA9 has proved to be a valuable marker in many cancers such as lung, breast, colon, kidney, etc. The present study was to evaluate MN/CA9 as a new molecular marker for the detection of cancer cells in pleural effusions. Seventy-one pleural effusions including 59 malignant effusions from patients with cancer, and 12 patients with benign diseases as a control, were subjected to RT-PCR for detection of MN/CA9 gene expression. MN/CA9 gene expression was detected in 53/59 (89.8%) pleural effusions from cancer patients (15/16 for breast cancers, 10/11 for lung cancers, 4/4 for ovary cancers, 2/3 for colon-rectal cancers, 5/6 for cancers of unknown site, 7/8 for mesothelioma and 10/11 for other cancers). Furthermore, MN/CA9 was positive in 13/18 (72.2%) of cytologically negative effusions of cancer patients. MN/CA9 was detected in only 1/12 (8.3%) effusions from the control patients (p < 0.01). The sensitivity and specificity of MN/CA9 gene expression were, respectively, 89.8% and 91.7%. Our preliminary results suggest that MN/CA9 could be a potential marker for the detection of malignant cells in effusions. A large-scale study is needed to confirm these results.

Evaluation of a panel of molecular markers for the diagnosis of malignant serous effusions

PURPOSE

Our main goal was to evaluate a panel of molecular markers for the detection of cancer cells in serous effusions and to determine their value as an adjunctive reverse transcription-PCR (RT-PCR) test to cytologic examination.

EXPERIMENTAL DESIGN

One hundred fourteen serous effusions from 71 patients with tumors and 43 patients with benign diseases were subjected to RT-PCR for expression of carcinoembryonic antigen (CEA), epithelial cell adhesion molecule (Ep-CAM), E-cadherin, mammaglobin, mucin 1 (MUC1) isoforms MUC1/REP, MUC1/Y, and MUC1/Z, calretinin, and Wilms' tumor 1 susceptibility gene.

RESULTS

CEA, Ep-CAM, E-cadherin, and mammaglobin were specifically expressed in malignant effusions. The sensitivity of RT-PCR in cytologically negative malignant effusions was 63.1% combining CEA and Ep-CAM (with 100% specificity) and reached 78.9% adding MUC1/Y or MUC1/Z (with 93% specificity). In the whole population of effusions, the combination of cytology with RT-PCR of CEA and Ep-CAM yielded a 90.1% sensitivity, a specificity and a positive predictive value of 100%, and a 86% negative predictive value for malignancy. Adding MUC1/Y or MUC1/Z to the panel, the sensitivity was 94.5% with 93% specificity, 95.7% PPV, and 90.9% negative predictive value. Moreover, CEA and mammaglobin were specifically expressed in epithelial malignancies, and mammaglobin was mainly expressed in effusions from breast carcinoma (97.3% of specificity).

CONCLUSIONS

A combination of cytology and RT-PCR analysis of CEA and Ep-CAM significantly improved the detection sensitivity of tumor cells in serous effusions. RT-PCR analysis of CEA, Ep-CAM, and mammaglobin in serous effusions could be a beneficial adjunct to cytology for the diagnosis of malignancy.

Histiocytoid breast carcinoma: Solid variant of invasive lobular carcinoma with decreased expression of both E-cadherin and CD44 epithelial variant

Histiocytoid breast carcinoma (HBC) is a rare type of breast carcinoma with morphologic characteristics resembling those of histiocytes. Described herein are cytological and histological findings in a case of HBC. Fine-needle aspiration cytology revealed numerous loosely cohesive tumor cells with abundant foamy to granular cytoplasm and bland-appearing nuclei. The resected tumor exhibited a solid growth pattern instead of classic invasive lobular patterns observed in most reported cases of HBC. However, distinct intracytoplasmic lumina and Pagetoid extension to ducts suggested that this tumor was a variant of invasive lobular carcinoma. To determine the cause of the loose cellular cohesiveness of this HBC, its expression of the epithelium-related cell adhesion molecules E-cadherin and CD44v8-10 (CD44 epithelial variant) was examined. Immunohistochemically, E-cadherin was not detected, similar to most lobular carcinomas. Furthermore, competitive reverse transcription-polymerase chain reaction (RT-PCR) analyses among alternatively spliced variants of CD44 revealed that the ratio of expression of CD44v8-10 to that of CD44v10 (dominant variant in leukocytes) was lower than that for the reference breast carcinoma samples. It is concluded that the present case of HBC was a solid variant of invasive lobular carcinoma exhibiting foamy to granular cytoplasmic change. Decreased expression of both E-cadherin and CD44 epithelial variant may be responsible for the loose cellular cohesiveness observed in HBC.

Detection of bladder carcinoma by combined testing of urine for hyaluronidase and cytokeratin 20 RNAs

BACKGROUND

A new, sensitive, noninvasive method for the detection of urothelial carcinomas of the urinary bladder would open new possibilities in both the diagnosis and followup of patients.

METHODS

This study included 228 patients diagnosed with bladder carcinoma, 68 patients with benign bladder lesions, and 44 healthy persons served as the control group. All were subjected to: serologic schistosomiasis antibody assay in serum, urine cytology, estimation of urine hyaluronic acid (HA) by enzyme-linked immunosorbent assay, and detection of CK-20 and hyaluronidase (HAase) by reverse transcription polymerase chain reaction (RT-PCR) in urothelial cells from voided urine.

RESULTS

HA mean rank was higher in benign and malignant groups than in the healthy group (P < 0.0001) and was significantly related to tumor grade (P = 0.021). HA best-cutoff, determined using receiver operating characteristic curve to discriminate between malignant and nonmalignant groups, was 58.5 units/mg protein at 85.8% sensitivity and 60.7% specificity. HAase RNA showed superior sensitivity (90.8%) over cytology (68.9%) and CK-20 (78.1%) with specificity of 93.4%, 98.1% and 80.2%, respectively. The sensitivity reached 94.7% at a specificity of 91.5% when combined with CK-20. All 4 of the investigated markers were related to grade at P <0.05. Whereas only HAase and CK-20 were significantly related to stage (P < 0.05). As to schistosomiasis, only HAase RNA positivity was significantly associated (P = 0.038).

CONCLUSIONS

HAase RNA is a promising noninvasive test with high sensitivity and specificity in bladder carcinoma detection.

Aberrant and Alternative Splicing in Cancer

Pre-mRNA splicing is a sophisticated and ubiquitous nuclear process, which is a natural source of cancer-causing errors in gene expression. Intronic splice site mutations of tumor suppressor genes often cause exon-skipping events that truncate proteins just like classical nonsense mutations. Also, many studies over the last 20 years have reported cancer-specific alternative splicing in the absence of genomic mutations. Affected proteins include transcription factors, cell signal transducers, and components of the extracellular matrix. Antibodies against alternatively spliced products on cancer cells are currently in clinical trials, and competitive reverse transcription-PCR across regions of alternative splicing is being used as a simple diagnostic test. As well as being associated with cancer, the nature of the alternative gene products is usually consistent with an active role in cancer; therefore, the alternative splicing process itself is a potential target for gene therapy.

Prostate cancer invasion is influenced more by expression of a CD44 isoform including variant 9 than by Muc18

The standard form of cell adhesion glycoprotein CD44 is a metastasis suppressor in prostate cancer. However, we previously showed by RT-PCR and Western blotting that cancer overexpresses unique CD44 variant v7-v10 isoforms. Muc18 is another cell adhesion marker reportedly overexpressed by prostate cancer. Matched frozen section-confirmed tumor and benign tissues were harvested from 10 prostatectomy specimens and tumor was microdissected from two lymph node metastases. Tissues were homogenized for RNA preparations, and RT-PCR was performed for the CD44v7-v10 sequence. In cultured prostate cancer cells, we caused RNA interference against CD44v9 and/or Muc18. We used PC3M cells and a derivative cell line called G(s)alpha, that constitutively expresses this G-protein and is more invasive. Lipofection was performed for a green fluorescent protein plasmid and for two 22-mer DNA fragments, cloned into a plasmid expression vector to generate hairpin, interfering dsRNA. Assays for invasion into Matrigel, a basement membrane matrix, were performed in 4-5 experiments. RT-PCR demonstrated expression of a 608 bp band representing CD44v7-v10 or a 638 bp band of CD44v6-v10 in prostate cancer tissues and metastases but not benign tissue. Cultured G(s)alpha cells overexpressed CD44v9 by comparison with PC3M cells. At 90 h after 6-hour lipofection, protein silencing was evident by Western blots. Silencing the CD44v9 expression reduced invasiveness into Matrigel to 21.6+/-7.0% in PC3M cells (P<0.001) and 31.2+/-18.3% in G(s)alpha cells (P=0.001), compared to cells exposed to transfection vehicle alone. Silencing Muc18 expression reduced invasiveness to 76.9+/-13.5% of the control value in PC3M cells (P<0.05) and 84.8+/-29.9% in G(s)alpha cells (P=0.18). Prostate cancer invasion is facilitated more by its overexpression of CD44 variant 9 than by Muc18. Its relative overexpression by G(s)alpha cells is a novel finding, suggesting a link between signal transduction and cell adhesion marker expression.

Combination of cytology, fluorescence in situ hybridization for aneuploidy, and reverse-transcriptase polymerase chain reaction for human mammaglobin/mammaglobin B expression improves diagnosis of malignant effusions

PURPOSE

The identification of malignant cells in effusions by conventional cytology is hampered by its limited sensitivity. The aim of this study was to improve tumor cell detection in effusions by molecular approaches.

MATERIALS AND METHODS

A total of 157 effusions from patients with tumors and 72 effusions from patients without a history or evidence of malignancy were included in this study. All effusion specimens were evaluated in parallel by cytology, fluorescence in situ hybridization (FISH) for aneuploidy, and reverse-transcriptase polymerase chain reaction (RT-PCR) for expression of human mammaglobin (hMAM) and mammaglobin B (hMAM-B).

RESULTS

In effusions from patients with tumors, the sensitivities of tumor cell detection by cytology, FISH, and hMAM and hMAM-B detection were 46.2%, 53.3%, 36.4%, and 57.7%, respectively. The corresponding specificities were 94.4%, 97.0%, 87.1%, and 88.6%. Notably, a high percentage of effusions containing malignant cells were in fact transudates, indicating the necessity for molecular diagnostic work-up of transudates collected from patients with tumors. Dependent on the tumor type, the use of appropriate marker combinations improved tumor cell detection in effusions significantly. By combining all four diagnostic tests, a positive test result indicating the presence of malignancy was achieved in 81.1%, with a fairly good specificity of 70.1%.

CONCLUSION

Molecular techniques are definitely useful to detect malignancy in cytologically negative effusions. Tumor cell detection in effusions can be significantly improved by FISH and PCR techniques applying appropriate molecular markers. This finding should help to improve tumor staging, prognostic assessment, and treatment monitoring.

Over expression of CD44V8-10 in human bladder cancer cells decreases their interaction with hyaluronic acid and potentiates their malignant progression

PURPOSE

We evaluated the effects of the over expression of CD44v8-10, one of the high molecular form of CD44, on the malignant potential of UM-UC-3 human bladder cancer cells in vitro and in vivo.

MATERIALS AND METHODS

We introduced CD44v8-10 complementary DNA into UM-UC-3 cells, which do not express detectable level of CD44v8-10 protein, and generated the CD44v8-10 over expressing cell line UM-UC-3/v8-10 and the vector only transfected cell line UM-UC-3/C. The effects of the introduction of CD44v8-10 into UM-UC-3 cells on the ability to bind hyaluronic acid (HA) were analyzed by the cell adhesion assay and the cell migration assay. We then evaluated tumor progression of UM-UC-3 sublines after subcutaneous and orthotopic injection into athymic nude mice.

RESULTS

There were no significant differences in in vitro growth rates. UM-UC-3/v8-10 cells showed significantly decreased binding and migration ability to HA but not to other extracellular matrix proteins. Furthermore, UM-UC-3/v8-10 cells demonstrated significantly increased tumor growth after subcutaneous as well as orthotopic injection into athymic nude mice and enhanced lymph node metastasis after orthotopic injection compared with UM-UC-3/C cells.

CONCLUSIONS

These findings suggest that CD44v8-10 over expression in human bladder cancer cells decreases their interaction with HA and potentiates their malignant progression.

[Polymerase chain reaction in the urinary diagnosis of bladder cancer]

The polymerase chain reaction (PCR) is a highly sensitive and specific method for the detection of genetic material. Over the last few years, this method has been used increasingly for the molecular detection of disease. This report demonstrates the use of PCR in the diagnosis of bladder cancer. The principles of the method are shown by describing the detection of p53, CD44 and telomerase, as well as in microsatellite analysis.

Molecular detection approaches for smoking associated tumors

Smoking is directly responsible for approximately 90% of lung cancers and is also strongly associated with cancers of the head and neck, esophagus and urinary bladder. Our growing understanding of the molecular changes that underlie cancer progression has contributed to the development of novel molecular approaches for the detection of cancer. In this study, we review a number of recent studies that have used molecular techniques to detect neoplastic DNA from lung, head and neck, esophagus and bladder cancer. The majority of these approaches are based on polymerase chain reaction (PCR) based assays. These PCR-based techniques can detect a few clonal cancer cells containing a specific DNA mutation, microsatellite alteration, or CpG island methylation among an excess background of normal cells. The ability to accurately detect a small number of malignant cells in a wide range of clinical specimens including sputum, saliva, bronchoalveolar lavage fluid, urine, serum, plasma, or tissue has significant implications for screening high-risk individuals (such as cigarette smokers) for cancer.

Analysis of homozygous deletion of the p16 gene and correlation with survival in patients with glioblastoma multiforme

OBJECT

One of the most frequent genetic abnormalities found in patients with glioblastoma multiforme (GBM) is homozygous deletion of the p16 tumor suppressor gene. The authors investigated whether this deletion is associated with prognosis in patients with GBM.

METHODS

In 46 adult patients with supratentorial GBM, homozygous deletion of the p16 gene in tumor DNA was examined using the multiplex polymerase chain reaction assay. The deletion was confirmed in 14 (30.4%) of 46 patients, eight (30.8%) of 26 men and six (30.0%) of 20 women. Cox proportional hazard regression analysis, adjusted for age at surgery, the Karnofsky Performance Scale score, extent of resection, and the MIB-1 labeling index. revealed that homozygous deletion of the p16 gene was significantly associated with overall survival and progression-free survival in men, but not in women.

CONCLUSIONS

The results of this study suggest that p16 homozygous deletion is a significant unfavorable prognostic factor in male patients with GBM.

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.

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.

Application of mucin quantitative competitive reverse transcription polymerase chain reaction in assisting the diagnosis of malignant pleural effusion

Aberrant expression of mucin genes occurs frequently in advanced cancer. Using quantitative competitive reverse transcriptase/polymerase chain reaction (QC RT-PCR), the expression of three mucin genes--MUC1 (widely expressed in epithelial cells), MUC2 (mainly expressed in intestinal epithelial cells), and MUC5AC (mainly from airway and gastric epithelial cells)--was evaluated in 112 patients with pleural effusions (including 54 cytologically positive malignant pleural effusions, 35 benign exudative pleural fluids, and 23 cytologically negative pleural effusions from cancer patients). The expression ratios of MUC1 and MUC5AC, but not MUC2 gene, were significantly higher in malignant than benign pleural fluids (p < 0.000). The cutoff value, sensitivity, and specificity of MUC1 expression ratio were: 0.126, 64.6%, and 95.7%; and were 0.028, 72.3%, and 95.7%, respectively, for MUC5AC. In combined evaluation with both MUC1 and MUC5AC, the sensitivity was 86.1% and specificity was 91.5%. The positive and negative predictive values were 93.3%, and 82.7%, respectively. We considered mucin QC RT-PCR to be a useful tool in assisting the diagnosis of malignant pleural effusion.

Detection of malignant cells in pleural fluid or ascites by CD44v8-10/CD44v10 competitive RT-PCR

BACKGROUND

CD44 is a cell surface adhesion molecule which has been implicated in various biologic functions as lymphocyte homing and activation, cellular migration and extracellular matrix adhesion. Over-expression of CD44v8-10 has been found in several cancers and is considered to be associated with tumor progression and metastasis. Recently, a novel molecular method, CD44v8-10/CD44v10 competitive reverse transcription-polymerase chain reaction(RT-PCR) has been developed for detecting cancer cells over-expressing CD44v8-10.

METHODS

We analyzed from benign and malignant pleural effusion and ascites by CD44 competitive RT-PCR and compared to the conventional cytology.

RESULTS

The CD44 competitive RT-PCR analysis showed that all the 24 samples associated with benign disease presented a predominant expression of the CD44v10 transcript (v8-10/v10 ratio: 0.126-0.948), whereas 6 of 7 malignant pleural samples associated with cytology positive cancer expressed the CD44v8-10 transcript (v8-10/v10 ratio > 1.00).

CONCLUSION

These results indicate that CD44 competitive RT-PCR assay is a useful and adjunct to cytological examination in cancer diagnosis, especially in detecting exfoliated cancer cells in pleural effusion.

Real-Time Quantification of Human Telomerase Reverse Transcriptase mRNA in Tumors and Healthy Tissues

Background: Expression of the hTERT gene, which codes for the catalytic subunit of telomerase, is associated with malignancy. We recently developed a real-time reverse transcription-PCR assay, based on TaqMan technology, for accurate and reproducible determination of hTERT mRNA expression (Lab Investig 1999;79:911–2). This method may be of interest for molecular tumor diagnostics in tissues and corresponding body fluids, washings, or brushes.

Methods: In this study, we measured hTERT expression in a subset of healthy tissues and tumors to select those tumor types with the best potential for quantification of hTERT in corresponding body fluids. To demonstrate the use of the method in body fluids, we quantified hTERT expression in voided urine of patients with bladder cancer and controls.

Results: Real-time measurement of hTERT expression could discriminate between all healthy and malignant tissue samples from pancreas, lung, esophagus, and bladder, but not for colon tissues. Moreover, in five of nine (55%) urine samples, hTERT could be quantified.

Conclusions: The present study demonstrates that accurate quantitative measurement of hTERT expression has high potential for discrimination between healthy and tumor cells in tissues and urine and supports future measurements in pancreatic fluid, bronchoalveolar lavage fluid, esophageal brushings, and urine or bladder washings.

Prognostic value of the expression of E-cadherin and beta-catenin in bladder cancer

The purpose of this study was to assess the prognostic effect of the expression of E-cadherin, beta-catenin and CD44 adhesion molecules in bladder carcinoma. 22 superficial and 18 invasive bladder tumour samples were studied by immunohistochemistry. The median follow-up was 24 months (range: 1-50 months). Loss of E-cadherin and beta-catenin immunoreactivity was found in 14 (35%) and 17 (43%) tumours, respectively, and was significantly associated with invasiveness, high grade and p53 overexpression. There was no correlation between CD44 variant expression and clinicopathological findings. Loss of E-cadherin expression was an independent predictor of poor survival in a multivariate analysis, when assessed with age, grade, stage and p53 status (hazards ratio adjusted (HRa)=4.45 [95% confidence interval (CI), 1.06-18.63]). This effect was particularly augmented in patients with invasive bladder cancer. When expression of E-cadherin and beta-catenin were evaluated simultaneously, loss of immunoreactivity of both proteins was a strong predictor of poor survival (HRa=13.06 [95% CI, 0.95-178.55]). The same pattern was found when progression-free survival in relation to these variables was assessed. In conclusion, assessment of E-cadherin and beta-catenin immunoreactivity may be a useful prognostic marker in bladder cancer complementary to established prognostic factors.

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.

CD44 cleavage induced by a membrane-associated metalloprotease plays a critical role in tumor cell migration

CD44 is a cell surface receptor for hyaluronate, a component of the extracellular matrix (ECM). Although CD44 has been implicated in tumor invasion and metastasis, the molecular mechanisms remain to be elucidated. Here we find that CD44 expressed in cancer cells is cleaved at the membrane-proximal region of the ectodomain and the membrane-bound cleavage product can be detected using an antibody against the cytoplasmic domain of CD44. Furthermore, we report that CD44 cleavage is mediated by a membrane-associated metalloprotease expressed in cancer cells. A tissue inhibitor of metalloproteases-1 (TIMP-1), as well as metalloprotease inhibitors, inhibit CD44 cleavage in the cell-free assay. Contrary, serine protease inhibitors enhance CD44 cleavage, and the enhancement can be prevented by pretreatment with a metalloprotease inhibitor. Thus, CD44 cleavage is regulated by an intricate balance between some proteases and their inhibitors. Interestingly, treatment with the metalloprotease blocker 1,10-phenanthroline, which strongly prevent the CD44 cleavage, suppressed RERF-LC-OK lung cancer cell migration on a hyaluronate substrate, but not on several other substrates. These results suggest that CD44 cleavage plays a critical role in an efficient cell-detachment from a hyaluronate substrate during the cell migration and consequently promotes CD44-mediated cancer cell migration. Our present data indicate that CD44, not only ECM per se, is one of the targets of pericellular proteolysis involved in tumor invasion and metastasis.