CD44: target for antiangiogenesis therapy

Androgen Receptor Regulates CD44 Expression in Bladder Cancer

The androgen receptor (AR) is important in the development of both experimental and human bladder cancer. However, the role of AR in bladder cancer growth and progression is less clear, with literature indicating that more advanced stage and grade disease are associated with reduced AR expression. To determine the mechanisms underlying these relationships, we profiled AR-expressing human bladder cancer cells by AR chromatin immunoprecipitation sequencing and complementary transcriptomic approaches in response to in vitro stimulation by the synthetic androgen R1881. In vivo functional genomics consisting of pooled shRNA or pooled open reading frame libraries was employed to evaluate 97 genes that recapitulate the direction of expression associated with androgen stimulation. Interestingly, we identified CD44, the receptor for hyaluronic acid, a potent biomarker and driver of progressive disease in multiple tumor types, as significantly associated with androgen stimulation. CRISPR-based mutagenesis of androgen response elements associated with CD44 identified a novel silencer element leading to the direct transcriptional repression of CD44 expression. In human patients with bladder cancer, tumor AR and CD44 mRNA and protein expression were inversely correlated, suggesting a clinically relevant AR-CD44 axis. Collectively, our work describes a novel mechanism partly explaining the inverse relationship between AR and bladder cancer tumor progression and suggests that AR and CD44 expression may be useful for prognostication and therapeutic selection in primary bladder cancer. SIGNIFICANCE: This study describes novel AREs that suppress CD44 and an expected inverse correlation of AR-CD44 expression observed in human bladder tumors.

PROGNOSTIC ROLE OF CD44 EXPRESSION AND NEOVASCULARIZATION DETERMINED BY ENDOGLIN (CD105) IN GLIOBLASTOMA PATIENTS

Glioblastoma multiforme (GBM) is the most common and most aggressive malignant primary brain tumor in humans. Clinically useful molecular markers that help predict response to therapy and prognosis are still rare. The research was conducted in 55 patients with GBM, 26 (47.3%) women and 29 (52.7%) men, mean age 62.58 years. On immunohistochemical analysis, primary antibody to CD44 (dilution 1:50) and primary antibody to endoglin (CD105) (dilution 1:250) were used to evaluate neovascularization. Statistical analysis showed negative correlation between CD44 and survival (p=0.023) (higher expression of CD44 was correlated with shorter survival), but there was no correlation between neovascularization determined by CD105 in GBM and patient survival. Thus, significant individual predictors of longer survival were lower expression of CD44 (p=0.004), higher Karnofsky score (p=0.045), and female gender (p=0.017). The results obtained suggested the possible role of CD44 in the progression and tumor neovascularization of GBM.

CD44 in canine leukemia: analysis of mRNA and protein expression in peripheral blood

Hyaluronan receptor CD44 mediates interaction between cells and extracellular matrix. The expression of standard form and its variants is dysregulated in human leukemias and is associated with metastasis and prognosis. The aim of this work is the evaluation of CD44 mRNA and protein expression in canine leukemia. Peripheral blood from 20 acute leukemias (AL) (10 acute lymphoblastic, 6 acute myeloid and 4 acute undifferentiated leukemias), 21 chronic lymphocytic leukemias (CLL) and thirteen healthy dogs were collected. The mRNA expression of all CD44 variants presenting exons 1-5 and/or 16-20 (CD44_ex1-5 and CD44_ex16-20) and CD44 protein were determined by real-time RT-PCR and flow cytometry, using the mean fluorescent index (MFI), respectively. CD44 MFI was significantly higher in leukemic samples compared to controls and a higher expression was found in AL in respect with CLL. No significant differences were found when considering different phenotypic subtypes of AL and CLL. CD44_ex1-5 mRNA expression was significantly higher in AL compared to controls, whereas there was no difference in CLL compared to controls and AL. CD44_es16-20 showed the same trend, but without differences among groups. The high CD44 expression found in canine leukemias could be considered a step toward the definition of their molecular features.

Prognostic value of serum CD44, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 levels in patients with indolent non-Hodgkin lymphomas

Elevated serum CD44, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been linked to poor prognosis in aggressive lymphomas, but their utility in low grade lymphomas remains undefined. We evaluated serum CD44, VCAM-1 and ICAM-1 levels in 100 patients with newly diagnosed indolent NHL. The median pre-treatment values of the markers were as follows: CD44 540 ng/mL (range 156-1201), ICAM-1 311 ng/mL (range 102-1222) and VCAM-1 1165 ng/mL (range 248-4779). On univariate analysis, elevated sCD44, sICAM-1 and sVCAM-1 were significantly associated with worse overall (OS) and progression-free survival (PFS). In a subset analysis of patients with stage IV disease, the effects of sCD44 and sICAM-1 on OS persisted (p<0.05), as did the effect of sCD44 on PFS (p<0.01). In a multivariate analysis that included conventional prognostic factors and the Follicular Lymphoma International Prognostic Index (FLIPI) model, sICAM-1 demonstrated prognostic value for OS and PFS. We conclude that serum CD44, ICAM-1 and VCAM-1 can potentially be prognostic in patients with indolent NHL. Though the FLIPI model remains the gold standard for prognosis, these quantitative serologic markers may be useful as adjunct tools in assessing disease risk.

An easy method to detect the kinetics of CD44 antibody and its receptors on B16 cells using atomic force microscopy

CD44 is the principle cell surface receptor for the extracellular matrix. The altered expression or dysfunction of CD44 proteins contributes to numerous pathological processes. Therefore, it is very necessary to detect the distribution and density of CD44 proteins on cell surface. In this paper, the unbinding force between the tip of an atomic force microscope modified with anti-human CD44 antibody (a kind of CD44 pathway ligation proteins, currently used to induce the apoptosis of some types of tumors) and B16 (human melanoma cell line) cells was measured. The results indicated that the distribution of CD44 was nonuniform and represented clusters on B16 cell surface. And, the data of kinetics of CD44 antibody-antigen binding experiments indicated that the CD44 signal pathway in B16 cells could be blocked by anti-CD44 monoclonal antibody. This methodology can be extended to the evaluation and screening of molecular targeted drugs for pharmacological use.