CD44 splice variants as prognostic markers in colorectal cancer

Targeting Hyaluronic Acid and Peritoneal Dissemination in Colorectal Cancer

Peritoneal metastasis (PM) from colorectal cancer (CRC) carries a significant mortality rate for patients and treatment is challenging. The development of PM is a multistep process involving detachment, adhesion, invasion and colonization of the peritoneal cavity. Cytoreductive surgery and HIPEC (hyperthermic intraperitoneal chemotherapy) for PM from CRC has some benefit but overall survival is poor and recurrence rates are high. Treatments to prevent the development of peritoneal metastasis could have the potential to improve CRC survival and disease-free outcomes. The ability of cancer cells to invade the peritoneum and become established as metastatic tumors is influenced by a multifactorial process. Hyaluronic acid (HA) has been shown to coat the mesothelial cells of the peritoneum and has been demonstrated to be utilized in various malignancies as part of the metastatic process in peritoneal dissemination. CD44, RHAMM (CD168) and ICAM-1 have all been shown to be binding partners for HA. Targeting HA-mediated binding may prevent adhesion to distant sites within the peritoneum through suppression of interaction of these molecules. Here we review the current literature and discuss key molecules involved with PM dissemination, with the potential to target these mechanisms in the delivery of future treatments.

Targeting stemness of cancer stem cells to fight colorectal cancers

Cancer initiating/ stem cells (CSCs) undergo self-renewal and differentiation that contributes to tumor initiation, recurrence and metastasis in colorectal cancer (CRC). Targeting of colorectal cancer stem cells (CCSCs) holds significant promise in eradicating cancer cells and ultimately curing patients with cancer. In this review, we will introduce the current progress of CCSC studies, including the specific surface markers of CCSCs, the intrinsic signaling pathways that regulate the stemness and differentiation characteristics of CCSCs, and the tumor organoid model for CCSC research. We will focus on how these studies will lead to the progress in targeting specific surface markers or signaling pathways on CCSCs by monoclonal antibodies, or by natural or synthetic compounds, or by immunotherapy. As CSCs are highly heterogeneous and plastic, we suggest that combinatory approaches that target the stemness network may represent an important strategy for eradicating cancers.

Colorectal tumor 3Din vitromodels: advantages of biofabrication for the recapitulation of early stages of tumour development

The majority of cancer-relatedin vitrostudies are conducted on cell monolayers or spheroids. Although this approach has led to key discoveries, it still has a poor outcome in recapitulating the different stages of tumor development. The advent of novel three-dimensional (3D) systems and technological methods for their fabrication is set to improve the field, offering a more physiologically relevant and high throughputin vitrosystem for the study of tumor development and treatment. Here we describe the fabrication of alginate-based 3D models that recapitulate the early stages of colorectal cancer, tracking two of the main biomarkers for tumor development: CD44 and HIF-1α. We optimized the fabrication process to obtain alginate micro-beads with controlled size and stiffness, mimicking the early stages of colorectal cancer. Human colorectal HCT-116 cancer cells were encapsulated with controlled initial number, and cell viability and protein expression of said 3Din vitromodels was compared to that of current gold standards (cell monolayers and spheroids). Our results evidenced that encapsulated HCT-116 demonstrated a high viability, increase in stem-like cell populations (increased expression of CD44) and reduced hypoxic regions (lower HIF-1a expression) compared to spheroid cultures. In conclusion we show that our biofabricated system is a highly reproducible and easily accessible alternative to study cell behavior, allowing to better mimic the early stages of colorectal cancer in comparison to otherin vitromodels. The use of biofabricatedin vitromodels will improve the translatability of results, in particular when testing strategies for therapeutic intervention.

CD44v6 overexpression related to metastasis and poor prognosis of colorectal cancer: A meta-analysis

CD44v6 has recently been reported as a biomarker for colorectal cancer. However, the clinical and prognostic significance of CD44v6 in colorectal cancer remains controversial. Therefore, we performed a meta-analysis to clarify this issue. A comprehensive literature search was performed using Medline, Embase and Web of Science, and the statistical analysis was conducted using Stata software. A total of twenty-one studies including 3918 colorectal cancer cases were included. The pooled analysis showed that CD44v6 overexpression in colorectal cancer was an independent prognostic marker correlating with lower 5-year overall survival rate (OR=0.78, 95%CI =0.67-0.91, p=0.001). CD44v6 overexpression was also associated with more lymph node invasion (OR=1.48, 95%CI= 1.02-2.15, p=0.04), and advanced Dukes stage (OR=2.47, 95%CI= 1.29-4.73, p=0.01). In addition, while excluding Zolbec's study, CD44v6 overexpression was associated with distance metastasis (OR=1.65, 95%CI =1.13-2.40, p=0.01). Taken together, this meta-analysis suggested that CD44v6 is an efficient prognostic factor in colorectal cancer.

MET Signaling Mediates Intestinal Crypt-Villus Development, Regeneration, and Adenoma Formation and Is Promoted by Stem Cell CD44 Isoforms

BACKGROUND & AIMS

Resistance of metastatic human colorectal cancer cells to drugs that block epidermal growth factor (EGF) receptor signaling could be caused by aberrant activity of other receptor tyrosine kinases, activating overlapping signaling pathways. One of these receptor tyrosine kinases could be MET, the receptor for hepatocyte growth factor (HGF). We investigated how MET signaling, and its interaction with CD44 (a putative MET coreceptor regulated by Wnt signaling and highly expressed by intestinal stem cells [ISCs] and adenomas) affects intestinal homeostasis, regeneration, and adenoma formation in mini-gut organoids and mice.

METHODS

We established organoid cultures from ISCs stimulated with HGF or EGF and assessed intestinal differentiation by immunohistochemistry. Mice with total epithelial disruption of MET (Ah^Cre/Met^fl/fl/LacZ) or ISC-specific disruption of MET (Lgr5^Creert2/Met^fl/fl/LacZ) and control mice (Ah^Cre/Met^+/+/LacZ, Lgr5^Creert2/Met^+/+/LacZ) were exposed to 10 Gy total body irradiation; intestinal tissues were collected, and homeostasis and regeneration were assessed by immunohistochemistry. We investigated adenoma organoid expansion stimulated by HGF or EGF using adenomas derived from Lgr5^Creert2/Met^fl/fl/Apc^fl/fl and Lgr5^Creert2/Met^+/+/Apc^fl/fl mice. The same mice were evaluated for adenoma prevalence and size. We also quantified adenomas in Ah^Cre/Met^fl/fl/Apc^fl/+ mice compared with Ah^Cre/Met^+/+/Apc^fl/+ control mice. We studied expansion of organoids generated from crypts and adenomas, stimulated by HGF or EGF, that were derived from mice expressing different CD44 splice variants (Cd44^+/+, Cd44^-/-, Cd44^s/s, or Cd44^v4-10/v4-10 mice).

RESULTS

Crypts incubated with EGF or HGF expanded into self-organizing mini-guts with similar levels of efficacy and contained all differentiated cell lineages. MET-deficient mice did not have defects in intestinal homeostasis. Total body irradiation reduced numbers of proliferating crypts in Ah^Cre/Met^fl/fl/LacZ mice. Lgr5^Creert2/Met^fl/fl/LacZ mice had impaired regeneration of MET-deficient ISCs. Adenoma organoids stimulated with EGF or HGF expanded to almost twice the size of nonstimulated organoids. MET-deficient adenoma organoids did not respond to HGF stimulation, but did respond to EGF. ISC-specific disruption of Met (Lgr5^Creert2/Met^fl/fl/Apc^fl/fl mice) caused a twofold increase in apoptosis in microadenomas, resulting in an approximately 50% reduction of microadenoma numbers and significantly reduced average adenoma size. Total epithelial disruption of Met (Ah^Cre/Met^fl/fl/Apc^fl/+ mice) resulted in an approximate 50% reduction in (micro)adenoma numbers. Intestinal crypts from Cd44^-/- mice did not expand to the same extent as crypts from Cd44^+/+ mice on stimulation with HGF, but had the same response to EGF. The negative effect on HGF-mediated growth was overcome by expression of CD44v4-10, but not by CD44s. Similarly, HGF-mediated expansion of adenoma organoids required CD44v4-10.

CONCLUSIONS

In studies of intestinal organoid cultures and mice with inducible deletion of MET, we found HGF receptor signaling to regulate intestinal homeostasis and regeneration, as well as adenoma formation. These activities of MET are promoted by the stem cell CD44 isoform CD44v4-10. Our findings provide rationale for targeting signaling via MET and CD44 during anti-EGF receptor therapy of patients with colorectal cancer or in patients resistant to EGF receptor inhibitors.

Identification of High-Risk Aberrant Crypt Foci and Mucin-Depleted Foci in the Human Colon With Study of Colon Cancer Stem Cell Markers

BACKGROUND

During colonoscopic screening, only macroscopic lesions will be identified, and these are usually the result of multiple genetic abnormalities. Magnification endoscopic detection of aberrant crypt foci (ACF), long before they acquire complex genetic abnormalities, is promising. However, the features of high-risk ACF-like lesions need to be identified.

MATERIALS AND METHODS

In the present cross-sectional study, grossly visible normal mucosal flaps were shaved from 152 colectomies, including 96 colorectal cancer (CRC) cases and 56 controls (22 control specimens with disease with malignant potential and 34 without malignant potential). Methylene and Alcian blue stains were performed directly on the unfixed mucosal flaps to identify ACF and mucin-depleted foci (MDF). Detailed topographic analyses, with immunohistochemical staining for β-catenin and cancer stem cell (CSC) markers (CD44, CD24, and CD166) were performed.

RESULTS

ACF, MDF, and β-catenin-accumulated crypts were detected more in specimens with adjacent CRC. The left colon had ACF with a larger diameter and greater crypt multiplicity, density, and gyriform pit pattern and were considered the high-risk ACF group. MDF, more commonly associated with dysplasia, is also a marker of possible carcinogenesis. The CD44 CSC marker was significantly upregulated in ACF specimens compared with normal controls. Our 3-tier ACF-only pit pattern classification system showed better linearity with mucosal dysplasia than did the 6-tier Kudo classification.

CONCLUSION

High-risk ACF, when detected during chromoendoscopic screening, should be followed up. CSCs might play an important role in pathogenesis. Larger studies and genotypic risk stratification for definite identification of high-risk ACF are needed.

Prognostic Significance of CD44v6, CD133, CD166, and ALDH1 Expression in Small Intestinal Adenocarcinoma

BACKGROUND

Small intestinal adenocarcinoma (SIAC) is a rare human malignant tumor. According to the cancer stem cell (CSC) hypothesis, only a small subpopulation of tumor cells has the ability to initiate and increase tumor growth. CD44v6, CD133, CD166, and ALDH1 have been proposed to be putative CSC markers in gastrointestinal malignancies. However, their implications in SIAC still remain unclear. We aimed to investigate the expressions of CD44v6, CD133, CD166, and ALDH1 and evaluate their relationships with clinicopathologic parameters including the survival data in SIACs.

MATERIALS AND METHODS

Immunohistochemical analysis for CD44, CD133, CD166, and ALDH1 was performed using tissue microarrays for 191 surgically resected SIACs.

RESULTS

CD44v6, CD133, CD166, and ALDH1 expression was found in 25 (13.5%), 58 (30.7%), 82 (44.1%), and 63 (33.3%) cases, respectively. CD44v6(+) was correlated with vascular tumor invasion (P=0.023). CD133(+) was marginally correlated with the histologic subtype of the tumors (P=0.085). Combined CD44v6(+)/CD133(+) was observed in 11 (5.9%) and was associated with a significantly worse survival rate by univariate (P=0.016) and multivariate (P=0.048; Cox hazard ratio, 2.403) analyses. .

CONCLUSIONS

Evaluation of the combined CD133 and CD44v6 expression could be a useful tool for predicting a poor outcome in patients with SIAC.

Roles of Proteoglycans and Glycosaminoglycans in Wound Healing and Fibrosis

A wound is a type of injury that damages living tissues. In this review, we will be referring mainly to healing responses in the organs including skin and the lungs. Fibrosis is a process of dysregulated extracellular matrix (ECM) production that leads to a dense and functionally abnormal connective tissue compartment (dermis). In tissues such as the skin, the repair of the dermis after wounding requires not only the fibroblasts that produce the ECM molecules, but also the overlying epithelial layer (keratinocytes), the endothelial cells, and smooth muscle cells of the blood vessel and white blood cells such as neutrophils and macrophages, which together orchestrate the cytokine-mediated signaling and paracrine interactions that are required to regulate the proper extent and timing of the repair process. This review will focus on the importance of extracellular molecules in the microenvironment, primarily the proteoglycans and glycosaminoglycan hyaluronan, and their roles in wound healing. First, we will briefly summarize the physiological, cellular, and biochemical elements of wound healing, including the importance of cytokine cross-talk between cell types. Second, we will discuss the role of proteoglycans and hyaluronan in regulating these processes. Finally, approaches that utilize these concepts as potential therapies for fibrosis are discussed.

Overexpression of c-Met and CD44v6 receptors contributes to autocrine TGF-β1 signaling in interstitial lung disease

The hepatocyte growth factor (HGF) and the HGF receptor Met pathway are important in the pathogenesis of interstitial lung disease (ILD). Alternatively spliced isoforms of CD44 containing variable exon 6 (CD44v6) and its ligand hyaluronan (HA) alter cellular function in response to interaction between CD44v6 and HGF. TGF-β1 is the crucial cytokine that induces fibrotic action in ILD fibroblasts (ILDFbs). We have identified an autocrine TGF-β1 signaling that up-regulates both Met and CD44v6 mRNA and protein expression. Western blot analysis, flow cytometry, and immunostaining revealed that CD44v6 and Met colocalize in fibroblasts and in tissue sections from ILD patients and in lungs of bleomycin-treated mice. Interestingly, cell proliferation induced by TGF-β1 is mediated through Met and CD44v6. Further, cell proliferation mediated by TGF-β1/CD44v6 is ERK-dependent. In contrast, action of Met on ILDFb proliferation does not require ERK but does require p38(MAPK). ILDFbs were sorted into CD44v6(+)/Met(+) and CD44v6(-)/Met(+) subpopulations. HGF inhibited TGF-β1-stimulated collagen-1 and α-smooth muscle cell actin expression in both of these subpopulations by interfering with TGF-β1 signaling. HGF alone markedly stimulated CD44v6 expression, which in turn regulated collagen-1 synthesis. Our data with primary lung fibroblast cultures with respect to collagen-1, CD44v6, and Met expressions were supported by immunostaining of lung sections from bleomycin-treated mice and from ILD patients. These results define the relationships between CD44v6, Met, and autocrine TGF-β1 signaling and the potential modulating influence of HGF on TGF-β1-induced CD44v6-dependent fibroblast function in ILD fibrosis.

Colorectal cancer biomarkers and the potential role of cancer stem cells

Over 50% of patients with colorectal cancer (CRC) will progress and/or develop metastases. Biomarkers capable of predicting progression, risk stratification and therapeutic benefit are needed. Cancer stem cells are thought to be responsible for tumor initiation, dissemination and treatment failure. Therefore, we hypothesized that CRC stem cell markers (CRCSC) can identify a group of patients whom are at increased risk for recurrence or progression of disease. If proven correct, these CRCSC biomarkers may herald a paradigm shift in the treatment of this deadly disease. This manuscript reviews current CRC evidence based screening modalities, patient stratification, and summarizes the current state of biomarkers and discusses the novel concept of putative CRCSC's as prognostic biomarkers.

Novel dual cyclooxygenase and lipoxygenase inhibitors targeting hyaluronan-CD44v6 pathway and inducing cytotoxicity in colon cancer cells

Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) enzyme have been found to play a role in promoting growth in colon cancer cell lines. The di-tert-butyl phenol class of compounds has been found to inhibit both COX-2 and 5-LOX enzymes with proven effectiveness in arresting tumor growth. In the present study, the structural analogs of 2,6 di-tert-butyl-p-benzoquinone (BQ) appended with hydrazide side chain were found to inhibit COX-2 and 5-LOX enzymes at micromolar concentrations. Molecular docking of the compounds into COX-2 and 5-LOX protein cavities indicated strong binding interactions supporting the observed cytototoxicities. The signaling interaction between endogenous hyaluronan and CD44 has been shown to regulate COX-2 activities through ErbB2 receptor tyrosine kinase (RTK) activation. In the present studies it has been observed for the first time, that three of our COX/5-LOX dual inhibitors inhibit proliferation upon hydrazide substitution and prevent the activity of pro-angiogenic factors in HCA-7, HT-29, Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressed in colon cancer cells, through inhibition of the hyaluronan/CD44v6 cell survival pathway. Since there is a substantial enhancement in the antiproliferative activities of these compounds upon hydrazide substitution, the present work opens up new opportunities for evolving novel active compounds of BQ series for inhibiting colon cancer.

Promising noninvasive cellular phenotype in prostate cancer cells knockdown of matrix metalloproteinase 9

Cell surface interaction of CD44 and MMP9 increases migration and invasion of PC3 cells. We show here that stable knockdown of MMP9 in PC3 cells switches CD44 isoform expression from CD44s to CD44v6 which is more glycosylated. These cells showed highly adhesive morphology with extensive cell spreading which is due to the formation of focal adhesions and well organized actin-stress fibers. MMP9 knockdown blocks invadopodia formation and matrix degradation activity as well. However, CD44 knockdown PC3 cells failed to develop focal adhesions and stress fibers; hence these cells make unstable adhesions. A part of the reason for these changes could be caused by silencing of CD44v6 as well. Immunostaining of prostate tissue microarray sections illustrated significantly lower levels of CD44v6 in adenocarcinoma than normal tissue. Our results suggest that interaction between CD44 and MMP9 is a potential mechanism of invadopodia formation. CD44v6 expression may be essential for the protection of non-invasive cellular phenotype. CD44v6 decrease may be a potential marker for prognosis and therapeutics.

A Pilot Study Assessing the Potential Role of non-CD133 Colorectal Cancer Stem Cells as Biomarkers

Introduction: Over 50% of patients with colorectal cancer (CRC) will progress and/or develop metastases. Biomarkers capable of predicting progression, risk stratification and therapeutic benefit are needed. Cancer stem cells are thought to be responsible for tumor initiation, dissemination and treatment failure. Therefore, we hypothesized that CRC cancer stem cell markers (CRCSC) will identify a group of patients at high risk for progression.

Methods: Paraffin-embedded tissue cores of normal (n=8), and histopathologically well-defined primary (n= 30) and metastatic (n=10) CRC were arrayed in duplicate on tissue microarrays (TMAs). Expression profiles of non-CD133 CRCSC (CD29, CD44, ALDH1A1, ALDH1B1, EpCam, and CD166) were detected by immunohistochemistry and the association with clinicopathological data and patient outcomes was determined using standard statistical methodology. An independent pathologist, blinded to the clinical data scored the samples. Scoring included percent positive cells (0 to 4, 0 = <10%, 1 = 10 - 24%, 2 = 25 - 49%, 3 = 50 - 74%, 4 = 75 - 100%), and the intensity of positively stained cells (0 to 4; 0 = no staining, 1 = diminutive intensity, 2 = low intensity, 3 = intermediate intensity, 4 = high intensity). The pathologic score represents the sum of these two values, reported in this paper as a combined IHC staining score (CSS).

Results: Of 30 patients 7 were AJCC stage IIA, 10 stage IIIB, 7 stage IIIC and 6 stage IV. Median follow-up was 113 months. DFI was 17 months. Median overall survival (OS) was not reached. Stage-specific OS was: II - not reached; III - not reached; IV - 11 months. In a univariate analysis, poor OS was associated with loss of CD29 expression; median OS, 32 months vs. not reached for CSS 3-7 vs. >7.5, respectively; p=0.052 comparing entire curves, after adjustment. In a Cox model analysis, loss of CD29 exhibited a trend toward association with survival (p=0.098) after adjusting for the effect of stage (p=0.0076). Greater expression of ALDH1A1 was associated with increasing stage (p=0.042 over stages 2, 3b, 3c, and 4) while loss of CD29 expression exhibited a trend toward being associated with stages 3 and 4 (p=0.08). Compared to normal colon tissue, primary tumors were associated with increased expression of ALDH1B1 (p=0.008). ALD1H1B1 expression level differed according to whether the tumor was moderately or poorly differentiated, well differentiated, or mucinous; the highest expression levels were associated with moderately or poorly differentiated tumors (p=0.011). Lymph node metastases were associated with a trend toward decreased expression of EpCAM (p = 0.06) when comparing 0 vs. 1 vs. 2+ positive lymph nodes, as was CD29 (p = 0.08) when comparing 0 vs. any positive lymph nodes. Compared to normal colon tissue metastatic colon cancers from different patients were associated with increased ALDH1B1 expression (p=0.001) whereas CD29 expression was higher in normal colonic tissue (p=0.014).

Conclusion: CD29 may be associated with survival as well as clinical stage and number of lymph nodes. ALDH1B1 expression was associated with differentiation as well as type of tissue evaluated. ALDH1A1 was associated with clinical stage, and decreased EpCAM expression was found in patients with advanced lymph node stage. CRCSCs may be useful biomarkers to risk stratify, and estimate outcomes in CRC. Larger prospective studies are required to validate the current findings.

Regulation of CD44 expression by tumor necrosis factor-α and its potential role in breast cancer cell migration

CD44 molecule plays critical role in distant malignant metastasis. It is expressed in standard form (CD44s) or variant form (CD44v). Tumor necrosis factor-α (TNF-α) is highly expressed in the cancer microenvironment. TNF-α was reported to modulate CD44 expression in several kinds of cancer. However, little is known about pathological role of TNF-α in breast cancer (BC) cells. In the current investigation, we investigated the effect of TNF-α on BC cells (MCF-7 and MDA-MB-231) viability, CD44 expression, and in vitro migration. We found that TNF-α down-regulated CD44s expression, up-regulated CD44v3 and CD44v6 expression through JNK pathway in MCF-7 cells. In MDA-MB-231 cells, TNF-α up-regulated CD44s, CD44v3 and CD44v6 expression via p38 pathway. These data indicate important role of CD44 molecule in BC pathology.

Enhanced mammary progesterone receptor-A isoform activity in the promotion of mammary tumor progression by dietary soy in rats

Dietary contribution to breast cancer risk, recurrence, and progression remains incompletely understood. Increased consumption of soy and soy isoflavones is associated with reduced mammary cancer susceptibility in women and in rodent models of carcinogenesis. In rats treated with N-methyl-N-nitrosourea, dietary intake of soy protein isolate (SPI) reduced mammary tumor occurrence but increased incidence of more invasive tumors in tumored rats, relative to the control diet casein. Here we evaluated whether mammary tumor progression in tumor-bearing rats lifetime exposed to SPI is associated with deregulated progesterone receptor (PR) isoform expression. In histologically normal mammary glands of rats with invasive ductal carcinoma lesions, PR-A protein levels were higher for SPI- than casein-fed rats, whereas PR-B was undetectable for both groups. Increased mammary PR-A expression was associated with higher transforming growth factor-beta1, stanniocalcin-1, and CD44 transcript levels; lower E-cadherin and estrogen receptor-alpha expression; and reduced apoptotic status in ductal epithelium. Serum progesterone (ng/ml) (CAS: 25.94 +/- 3.81; SPI: 13.19 +/- 2.32) and estradiol (pg/ml) (CAS: 27.9 +/- 4.49; SPI: 68.48 +/- 23.87) levels differed with diet. However, sera from rats of both diet groups displayed comparable mammosphere-forming efficiency in human MCF-7 cells. Thus, soy-rich diets may influence the development of more aggressive tumors by enhancing PR-A-dependent signaling in premalignant breast tissues.

Prognostic impact of the expression of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and ALDH1 in colorectal cancer

Background:

The aim of this study was to elucidate the prognostic impact of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and aldehyde dehydrogenase-1 (ALDH1) in colorectal cancer.

Methods:

A tissue microarray of 1420 primary colorectal cancers and 57 normal mucosa samples was immunostained for CD133, CD166, CD44s, EpCAM, and ALDH1 in addition to 101 corresponding whole tissue sections. Invasive potential of three colorectal cancer cell lines was tested.

Results:

Differences between normal tissue and cancer were observed for all markers (P<0.001). Loss of membranous CD166 and CD44s were linked to higher pT (P=0.002, P=0.014), pN (P=0.004, P=0.002), an infiltrating growth pattern (P<0.001, P=0.002), and worse survival (P=0.015, P=0.019) in univariate analysis only. Loss of membranous EpCAM expression was also linked to higher pN (P=0.023) and infiltrating growth pattern (P=0.005). The CD44s, CD166, and EpCAM expression were lost towards the invasive front. The CD44−/CD166− cells from three colorectal cancer cell lines exhibited significantly higher invasive potential in vitro than their positive counterparts.

Conclusions:

Loss, rather than overexpression, of membranous CD44s, CD166, and EpCAM is linked to tumour progression. This supports the notion that the membranous evaluation of these proteins assessed by immunohistochemistry may be representative of their cell adhesion rather than their intra-cellular functions.

Systematic assessment of the prognostic impact of membranous CD44v6 protein expression in colorectal cancer

AIMS

To assess systematically the membranous expression of CD44v6 in colorectal cancer by immunohistochemistry to determine its prognostic impact, the differential expression between primary and metastatic tumours and expression differences between the tumour centre and invasive front.

METHODS AND RESULTS

Immunohistochemistry was performed for CD44v6 on two tissue microarrays. The first included 1279 colorectal tumours with full clinicopathological data. The second consisted of 50 matched primary and metastatic tumours sampled from the tumour centre and the invasive margin. A scoring system was tested by multiple observers. Receiver-operating characteristic curve analysis was used for cut-off point determination. Loss of membranous CD44v6 was associated with pT stage (P = 0.016; sensitivity 85.8%, specificity 20.1%), lymph node metastasis (P = 0.015; sensitivity 52.8%, specificity 55%), an infiltrating tumour margin (P < 0.001; sensitivity 71.4%, specificity 40%) and adverse prognosis (P = 0.011; hazard ratio 0.79, 95% confidence interval 0.7, 0.9), but was not an independent prognostic factor on multivariable analysis. Loss of expression occurred at the invasive front in both primary and metastatic lesions (P < 0.001).

CONCLUSIONS

This study outlines an approach to help standardize the immunohistochemical evaluation of CD44v6 and similar markers in colorectal cancer and highlights a significant role for loss of membranous CD44v6 expression in colorectal cancer progression and prognosis.

Peanut lectin stimulates proliferation of colon cancer cells by interaction with glycosylated CD44v6 isoforms and consequential activation of c-Met and MAPK: functional implications for disease-associated glycosylation changes

Peanut agglutinin lectin (PNA) binds the Thomsen-Friedenreich (TF) oncofetal carbohydrate antigen (galactose beta1-3N-acetylgalactosamine alpha) that shows increased expression in colon cancer, adenomas, and inflammatory bowel disease. PNA is mitogenic, both in vitro and in vivo, for colon epithelial cells. In these cells, PNA binds predominantly to cell-surface TF antigen expressed by high molecular weight isoforms of the transmembrane glycoprotein CD44 that are generated in inflamed and neoplastic colonic epithelia by altered RNA splicing. Our aim was to identify the signaling mechanism underlying the proliferative response to PNA. This was investigated in HT29, T84, and Caco2 colon cancer cells. Parallel lectin and immunoblotting of PNA affinity-purified HT29 cell membrane extracts showed PNA binding to high molecular weight CD44v6 isoforms. Within 5 min, PNA (25 microg/mL) caused a 6-fold increase in phosphorylation of hepatocyte growth factor receptor c-Met, known to co-associate with CD44v6. This was followed by the downstream activation of p44/p42 mitogen-activated protein kinase (MAPK) over 15-20 min. The presence of 100 microg/mL asialofetuin, a TF antigen-expressing glycoprotein, blocked both PNA-induced c-Met and MAPK activation. A similar PNA-induced c-Met and MAPK phosphorylation was also seen in T84 cells that express CD44v6 but not in Caco2 cells that lack CD44v6. PNA-induced cell proliferation was completely blocked by 1 microM PD98059, an inhibitor of MAPK activation (p < 0.0001). The expression of TF antigen by CD44 isoforms in colonic epithelial cells allows lectin-induced mitogenesis that is mediated by phosphorylation of c-Met and MAPK. It provides a mechanism by which dietary, microbial, or endogenous galactose-binding lectins could affect epithelial proliferation in the cancerous and precancerous colon.

Expression of cell adhesion molecule CD44v6 in hepatocellular carcinoma

AIM: To investigate the expression of cell adhesion molecule CD44v6 in hepatocellular carcinoma (HCC) and it's effect on the biological behavior of HCC.

METHODS: The expression of CD44v6 was detected in liver tissue specimens of patients with hepatic cell carcinoma (n = 32), portal hypertension (n = 8)and hepatic trauma (n = 5) by immunohistochemical staining. The level of CD44v6 expression and its relationship with some biological behaviors (capsule invasion, intrahepatic or extrahepatic metastasis and accompanied cirrhosis) and indexes [Edmonson grading and alpha fetoprotein (AFP) level] were analyzed.

RESULTS: CD44v6 expression was found negative or weak positive in some lymphocytes and interstitial cells in trauma and cirrhosis groups, while strong positive CD44v6 expression was observed in 25 cases of HCC group and CD44v6 was mainly located in cell plasma and membrane. The positive rate in HCC group was significantly higher than that in trauma and cirrhosis group (78.2% vs 40.0%, 62.3%; P<0.05). The level of CD44v6 expression in HCC group was significantly higher than that in trauma and cirrhosis group (113.3 13.3 vs 23.6 10.6, 42.4 12.3 positive cells, P<0.05). CD44v6 expression was markedly higher in capsule invasion, Edmonson grading IV, and metastasis group than that in non-capsule invasion, Edmonson grading II-III and non-metastasis group (125.9 14.7 vs 95.2 15.2, P<0.05; 122.5 24.3 vs 99.4 15.3, P<0.05; 165.4 17.5 vs 95.3 12.4, P<0.01). CD44v6 expression was not significantly related to tumor size, AFP level and hepatic cirrhosis (P>0.05).

CONCLUSION: CD44v6 can be one possible indicator to evaluate the malignancy and metastasis of hepatocellular carcinoma. Further study should be performed on the role of CD44v6 in biological behaviors and mechanisms of HCC.

Epithelial hyaluronic acid and CD44v6 are mutually involved in invasion of colorectal adenocarcinomas and linked to patient prognosis

Desmoplastic stroma of colorectal adenocarcinomas contains a variety of extracellular matrix molecules, including hyaluronic acid (HA). Overexpression of the HA receptor CD44 and, in particular, its splicing variant CD44v6 has been described as a prognostic factor for patients with colorectal adenocarcinomas in some studies, but converse reports also exist. Our hypothesis is that these divergent results may be related to the fact that the function of CD44v6 depends on the HA content of cell-surrounding matrix. Therefore, we studied the expression of HA and CD44v6 in tissue samples of 145 patients suffering from colorectal adenocarcinomas using immunohistochemistry. Expression of HA was separately evaluated in tumor epithelium and stroma. We additionally examined the influence of HA on invasion and adhesion of colorectal adenocarcinoma cells in vitro. The results show that epithelial HA expression was not correlated with tumor stage but with lymph-node or distant metastasis. Patients with tumors expressing epithelial HA had a decreased overall survival ( P=0.017) as well as tumors with coexpression of epithelial HA and CD44v6 ( P=0.011). The latter issue remained an independent prognostic factor in multivariate analysis (relative risk 5.06; 95% confidence interval, 1.18-21.57; P=0.028). HA exclusively stimulated in vitro invasion of CD44v6-expressing cells. This stimulation was partly reversed by an anti-CD44v6 antibody. Our findings suggest that the adverse prognostic effect of CD44v6 in colorectal adenocarcinoma might be restricted to those tumors that have pericellular HA.

Expression and clinical significance of CD44V5 and CD44V6 in resectable colorectal cancer

PURPOSE

This study was conducted to evaluate the prognostic significance of CD44v5 and CD44v6 in resectable colorectal cancer.

MATERIALS AND METHODS

Membranous CD44v5 and CD44v6 levels were measured by an immunoenzymatic assay in tumors and surrounding mucosal samples obtained from 105 patients with resectable colorectal carcinomas.

RESULTS

There were no significant differences of CD44v5 levels between tumors [median: 3.2 (range: 0.9-83.5) ng/mg protein) and surrounding mucosal samples (3 (3-146.2) ng/mg protein]. However, tumor samples showed significantly higher CD44v6 levels [19.5 (2.2-562.9) ng/mg protein] than mucosal samples [5 (5-230) ng/mg protein] (P=0.0001). Patients with higher CD44v5 or CD44v6 content in tumor samples had a considerably shorter relapse-free survival (P<0.05, for both). Patients with a higher CD44v6 content also had a shorter relapse-free and overall survival in the multivariate analysis (P<0.05).

CONCLUSION

The results of this study suggest a role of CD44v5 and CD44v6 in colorectal cancer progression. Membranous CD44v levels in primary tumors, measured by immunoenzymatic assay, may contribute to a more precise prognostic estimation in patients with resectable colorectal cancer.

Motility of colon cancer cells: modulation by CD44 isoform expression

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

Downregulation of CD44v6 in colorectal carcinomas is associated with hypermethylation of the CD44 promoter region

Overexpression of the cell adhesion protein CD44v6 has been demonstrated in colorectal cancer and other gastrointestinal tumors. While CD44v6 is upregulated in benign colorectal adenomas and well-differentiated colorectal cancer tissues, downregulation frequently occurs during disease progression. The mechanism of downregulation, however, is unknown. Therefore, we evaluated the methylation status of the CD44 promoter as a mechanism for decreased CD44v6 expression in advanced colorectal carcinomas. We demonstrated by methylation-sensitive restriction enzyme digestion that the CpG islands of the CD44 promoter were methylated in 6/21 (28%) of benign colorectal adenomas. Interestingly, in colorectal carcinomas the frequency of promoter methylation was significantly increased (10/19; 53%) compared to 7/21 (33%) in the corresponding normal mucosa. Methylation seems to be associated with a more advanced cancer stage, but the trend did not reach statistical significance. In colorectal carcinomas with CD44 promoter methylation CD44v6 mRNA was detected by reverse transcription-polymerase chain reaction in 3/10 carcinomas, whereas in tumors without CD44 promoter methylation CD44v6 expression was observed in 8/9 (P <or= 0.05). These results demonstrated that methylation of the 5'CpG island of the CD44 gene is closely associated with decreased expression of CD44v6 in human colorectal carcinomas.

Prediction of distant metastases after curative surgery for rectal cancer

BACKGROUND

This study was performed to define selection criteria for adjuvant therapy in rectal cancer.

MATERIALS AND METHODS

An immunohistochemical analysis using nine monoclonal antibodies against CEA, CD15s, CD44v6, DCC, E-cadherin, EGF-R, NM23, PAI-1, and P53 was performed on paraffin sections of two matched (age, gender, UICC stage [I-III], year of operation [1982-1991]) groups of patients (n = 2 x 64) with rectal carcinoma curatively treated by surgery alone. The two groups differed only with regard to metachronous distant metastatic spread. In order to exclude the influence of surgery, all patients had to meet the selection criterion "free of locoregional disease." Follow-up was prospective (median 80 months). Conventional staining procedures and immunohistochemical evaluation were used. Tumor grading and lymphatic and extramural venous invasion were also investigated. Analysis was performed with Fisher's exact test and Kaplan-Meier estimates of disease-free survival (log rank). The Cox model was used for multivariate analysis.

RESULTS

In univariate analysis only grading (P < 0.001) and extramural venous invasion (P < 0.001) correlated significantly with metachronous metastases. In multivariate analysis, beside grading (P = 0.010) and extramural venous invasion (P = 0.011), CD15s (P = 0.042) was also of significance. All other immunohistochemical markers failed.

CONCLUSIONS

The histopathological parameters grading and extramural venous invasion appear to be acceptable predictors of metachronous distant spread in curatively resected rectal cancer. In contrast to the immunohistochemical markers, grading seems to better reflect the individual tumor phenotype and its behavior.

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

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

Stage-specific alternative cplicing of CD44 and alpha 6 beta 1 integrin in colorectal tumorigenesis

Recent reports suggest that cancerogenesis induces changes in alternative processing of human genes. However, little is known about the regulation of alternative splicing during malignant transformation. Therefore, we examined changes in alternative splicing of two different adhesion molecules, alpha 6 beta 1 integrin and CD44, in multiple stages of colon tumorigenesis. Using semiquantitative RT-PCR it is shown that the alternatively spliced isoforms of both adhesion molecules, alpha 6A and -B and CD44v6, are significantly upregulated in colorectal adenoma (n = 20) compared to normal colon mucosa (n = 32) (P < 0.01). Although beta1 isoforms were expressed in almost all tissues, there was a significant increase in the intensity of gene expression of beta 1A compared to beta 1B (P <0.05) in adenoma tissue. Interestingly, CD44v6 and alpha 6 variant isoforms were downregulated in carcinoma tissue (n = 28) compared to adenoma. These results establish a link between neoplastic transformation and alternative splicing of cell adhesion molecules. Furthermore, these data suggest that colon epithelial cells carrying splice variants of adhesion molecules might acquire a selective growth advantage during early tumorigenesis.

Reduced CD44 standard expression is associated with tumour recurrence and unfavourable outcome in differentiated thyroid carcinoma

CD44 was detected with an antibody recognizing all forms of CD44 (CD44 standard) and others specific for its v3 and v6 variant isoforms; their prognostic value was evaluated in 213 patients with differentiated thyroid carcinoma (DTC). The staining patterns of CD44 standard (s) and CD44v6 in tumour tissue were quite similar, 176 cases (83%) being highly positive for CD44s and 153 cases (72%) for CD44v6. Only 18 (9%) tumours showed high expression of CD44v3. Papillary carcinomas were significantly more often high expressors of CD44s and CD44v6 than follicular carcinomas (p<0.001 for both). Age older than 60 years, distant metastases, and advanced pTNM stage were related to loss of expression of CD44s (p<0.001, p=0.021, and p=0.003, respectively). Tumour recurrence and cancer-related mortality were related to the reduced level of CD44s (p=0.049 and p=0.042). CD44v3 did not associate with any of the clinicopathological factors. In univariate analysis, CD44s was the only significant prognostic factor for disease-free survival (p=0.0488). In multivariate analysis, CD44s and thyroglobulin level were significant prognostic factors for disease-free survival (p=0.040 and p<0.001, respectively). The reduced level of CD44s in DTC patients seems to be an independent prognostic factor for unfavourable disease outcome.

Expression of c-Met and heparan-sulfate proteoglycan forms of CD44 in colorectal cancer

In colorectal cancer patients, prognosis is not determined by the primary tumor but by the formation of distant metastases. Molecules that have been implicated in the metastatic process are the proto-oncogene product c-Met and CD44 glycoproteins. Recently, we obtained evidence for functional collaboration between these two molecules: CD44 isoforms decorated with heparan sulfate chains (CD44-HS) can bind the c-Met ligand, the growth and motility factor hepatocyte growth factor/scatter factor (HGF/SF). This interaction strongly promotes signaling through the receptor tyrosine kinase c-Met. In the present study, we explored the expression of CD44-HS, c-Met, and HGF/SF in the normal human colon mucosa, and in colorectal adenomas and carcinomas, as well as their interaction in colorectal cancer cell lines. Compared to the normal colon, CD44v3 isoforms, which contain a site for HS attachment, and c-Met, were both overexpressed on the neoplastic epithelium of colorectal adenomas and on most carcinomas. Likewise, HGF/SF was expressed at increased levels in tumor tissue. On all tested colorectal cancer cell lines CD44v3 and c-Met were co-expressed. As was shown by immunoprecipitation and Western blotting, CD44 on these cells lines was decorated with HS. Interaction with HS moieties on colorectal carcinoma (HT29) cells promoted HGF/SF-induced activation of c-Met and of the Ras-MAP kinase pathway. Interestingly, survival analysis showed that CD44-HS expression predicts unfavorable prognosis in patients with invasive colorectal carcinomas. Taken together, our findings indicate that CD44-HS, c-Met, and HGF/SF are simultaneously overexpressed in colorectal cancer and that HS moieties promote c-Met signaling in colon carcinoma cells. These observations suggest that collaboration between CD44-HS and the c-Met signaling pathway may play an important role in colorectal tumorigenesis.

Loss of standard type of CD44 expression in invaded area as a good indicator of lymph-node metastasis in colorectal carcinoma

PURPOSE

Recent advances have made possible the treatment of small invasive colorectal cancer by means of polypectomy or endoscopic mucosal resection. CD44 expression in cancer cells was identified as an indicator of lymph-node metastasis, which could be evaluated in specimens removed by colonoscopy.

METHODS

The correlation between lymph-node metastasis and the expression of standard-type CD44 in cancer cells was examined immunohistologically using the invaded cancer cells of 61 tissue samples of superficially invasive colorectal cancer. We defined the above as invasive cancer restricted within the colorectal wall. Of the 61 samples, 31 had submucosal invasion and 30 had muscular invasion.

RESULTS

Standard-type CD44 expression in the area of invasion in cases with lymph-node metastasis was remarkably down-regulated. In 43 cases with no lymph-node metastasis, 36 (83.7 percent) of patients had CD44 expression in invaded cells, whereas only two of 18 cases (11.1 percent) with lymph-node metastasis had expression of standard-type CD44 in the same area (P < 0.0001). A total of 69.6 percent (16/23) of patients with loss of standard-type CD44 expression in invaded sites were found to have positive metastasis in the lymph nodes. These results suggest that standard-type CD44 in invasive colon cancer cells could suppress metastasis to the regional lymph nodes.

CONCLUSION

In cases of invasive colorectal cancer, the loss of standard-type CD44 expression in the invaded area is a sensitive marker for metastasis to the lymph nodes. Further investigation with larger patient groups is required to clarify the reliability of loss of standard-type CD44 expression as an indicator for additional surgery after endoscopic resection of submucosal invasive colorectal carcinoma.

Expression of CD44 variant exons in acute myeloid leukemia is more common and more complex than that observed in normal blood, bone marrow or CD34+ cells

CD44 is an adhesion molecule that is expressed on hematopoietic cells and has been implicated in the interactions between bone marrow stromal layers and hematopoietic progenitors. The expression of variant forms of CD44, particularly forms containing exon v6, have been associated with poor prognosis in a number of hematological malignancies. The expression of CD44 variants on normal bone marrow (BM), peripheral blood (PBMC) and CD34+ hematopoietic progenitors was compared with those expressed on blasts from 30 patients with acute myeloid leukemia (AML). Normal BM, PBMC and CD34+ progenitor cells were negative for all variants tested by flow cytometry. In contrast exon v3 was expressed on 13%, v4 on 67%, v5 on 19%, v6 on 7% and v7 on 65% of AML cases. RT-PCR and Southern blotting revealed the expression of exons v3, v6, v8, v9 and v10 in normal bone marrow and peripheral blood mononuclear cells and the expression of exons v3, v6, v8 and v10 in CD34+ progenitors. A more complex pattern of variant exon expression was observed in leukemic samples in comparison to normal hematopoietic cells. Sixty-two percent of AML cases expressed exon v3 and 70% exon v6. Exons v4 and v5 were not detected while exons v7, v8, v9 and v10 were detected in 21, 83, 71 and 92% of cases, respectively. In summary, our data demonstrate a striking increase in the complexity of CD44 variant expression in cells from patients with AML, along with surface expression of some variant CD44 proteins. Further analysis will be directed at how these alter the interaction of leukemic blasts with the bone marrow microenvironment and their diagnostic, prognostic and therapeutic potential.

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

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

Protein expression of CD44 (standard and variant isoforms) in hepatocellular carcinoma: relationships with tumor grade, clinicopathologic parameters, p53 expression, and patient survival

BACKGROUND/AIMS

Members of the CD44 family are transmembrane glycoproteins which act mainly as receptors for hyaluronan. We have examined the expression of CD44s and several CD44v and the relationship between these and hepatocellular carcinoma (HCC) grade, clinicopathological parameters, p53 expression, and patient survival in HCC.

METHODS

Formalin-fixed, paraffin-embedded tissue sections from 107 surgically resected HCC were examined immunohistochemically using a semi-quantitative scoring system to detect the expression of different forms of CD44.

RESULTS

The number of CD44s-positive cases was 36 (34%), CD44v5 52 (49%), CD44v6 29 (27%), CD44v7-8 41 (38%), and CD44v10 26 (24%). Expression of these molecules correlated with high histological grade, being the highest in poorly-differentiated HCC. High CD44v6 expression significantly correlated with the presence of vascular invasion and p53 overexpression. Kaplan-Meier examination of patient survival revealed that HCC patients with positivity of each of these five molecules had a reduced survival rate, and that HCC patients positive for all the five CD44 molecules had worse survival than HCC patients positive for four or less of these CD44 molecules. In multivariate survival analysis, CD44s positivity was an independent factor. However, positivity for one or more CD44 isoforms was the most useful independent factor for overall survival.

CONCLUSION

These results suggest that up-regulation of CD44 isoforms is associated with poorly-differentiated HCC and shortened survival.

Focal loss of CD44 variant protein expression is related to recurrence in superficial bladder carcinoma

The majority of papillary transitional cell carcinomas of the bladder are localized tumors at initial diagnosis; identification of those developing recurrence and an aggressive behavior is important. CD44 variant proteins have been implicated in tumor progression and metastasis, and a correlation with adverse prognosis has been demonstrated in a variety of human tumors. Here, the usefulness of conventional CD44 protein immunohistochemistry as a prognostic parameter for recurrence of superficial transitional cell carcinomas was assessed in paraffin sections of 241 tumors with long-term follow-up. A highly significant association was found between focal loss of CD44v3 and -v6 immunostaining and short recurrence-free interval in noninvasive (pTa) transitional cell carcinomas (P = 0.005), but not in minimally invasive (pT1) carcinomas (P = 0.78). Our results indicate the value of conventional CD44 immunohistochemistry as an additional tool for identifying patients at high risk for recurrence of pTa transitional cell carcinomas. They also point to biological differences between noninvasive and minimally invasive transitional cell carcinomas of the bladder.

Expression of CD44 in Apc and Tcf mutant mice implies regulation by the WNT pathway

Overexpression of cell surface glycoproteins of the CD44 family is an early event in the colorectal adenoma-carcinoma sequence. This suggests a link with disruption of APC tumor suppressor protein-mediated regulation of beta-catenin/Tcf-4 signaling, which is crucial in initiating tumorigenesis. To explore this hypothesis, we analyzed CD44 expression in the intestinal mucosa of mice and humans with genetic defects in either APC or Tcf-4, leading to constitutive activation or blockade of the beta-catenin/Tcf-4 pathway, respectively. We show that CD44 expression in the non-neoplastic intestinal mucosa of Apc mutant mice is confined to the crypt epithelium but that CD44 is strongly overexpressed in adenomas as well as in invasive carcinomas. This overexpression includes the standard part of the CD44 (CD44s) as well as variant exons (CD44v). Interestingly, deregulated CD44 expression is already present in aberrant crypt foci with dysplasia (ACFs), the earliest detectable lesions of colorectal neoplasia. Like ACFs of Apc-mutant mice, ACFs of familial adenomatous polyposis (FAP) patients also overexpress CD44. In sharp contrast, Tcf-4 mutant mice show a complete absence of CD44 in the epithelium of the small intestine. This loss of CD44 concurs with loss of stem cell characteristics, shared with adenoma cells. Our results indicate that CD44 expression is part of a genetic program controlled by the beta-catenin/Tcf-4 signaling pathway and suggest a role for CD44 in the generation and turnover of epithelial cells.