A multidrug-resistant ovarian carcinoma cell line with a malignant suppressed phenotype is a CD44 gene expression defective mutant

Epithelial ovarian cancer stem cells: underlying complexity of a simple paradigm

The lack of significant progress in the treatment of epithelial ovarian cancer (EOC) underscores the need to gain a better understanding of the processes that lead to chemoresistance and recurrence. The cancer stem cell (CSC) hypothesis offers an attractive explanation of how a subpopulation of cells within a patient's tumour might remain refractory to treatment and subsequently form the basis of recurrent chemoresistant disease. This review examines the literature defining somatic stem cells of the ovary and fallopian tube, two tissues that give rise to EOC. In addition, considerable research has been reviewed, that has identified subpopulations of EOC cells, based on marker expression (CD133, CD44, CD117, CD24, epithelial cell adhesion molecule, LY6A, ALDH1 and side population (SP)), which are enriched for tumour initiating cells (TICs). While many studies identified either CD133 or CD44 as markers useful for enriching for TICs, there is little consensus. This suggests that EOC cells may have a phenotypic plasticity that may preclude the identification of universal markers defining a CSC. The assay that forms the basis of quantifying TICs is the xenograft assay. Considerable controversy surrounds the xenograft assay and it is essential that some of the potential limitations be examined in this review. Highlighting such limitations or weaknesses is required to properly evaluate data and broaden our interpretation of potential mechanisms that might be contributing to the pathogenesis of ovarian cancer.

CD44 standard form expression is correlated with high-grade and advanced-stage ovarian carcinoma but not prognosis

Single-chain glycoprotein CD44 is a major cell surface receptor for hyaluronan and mediates epithelial cell adhesion by its involvement in cell-cell and cell-matrix interactions. Recently, CD44 has been identified as a biomarker of cancer stem cells in many malignancies including ovarian carcinoma. However, its clinical significance in human ovarian carcinoma has been controversial until recently. The aim of our current study was to clarify the clinical role of CD44 expression in human ovarian carcinoma. Immunohistochemical staining of 483 primary ovarian carcinoma and 27 paired primary and recurrent ovarian carcinoma samples for CD44 standard form (CD44s) was performed using tissue microarray. The associations between CD44s expression and clinical factors (histologic types, tumor grade, International Federation of Gynecology and Obstetrics stage, and response to chemotherapy), and overall or disease-free survivals were analyzed. We observed CD44s expression in 38% of the ovarian carcinoma samples. Results of the Fisher exact test suggested that CD44s expression was associated with high-grade carcinoma (P = .013), advanced International Federation of Gynecology and Obstetrics stage (III-IV; P < .001), age at diagnosis less than 60 years (P = .011), and transitional cell carcinoma (P = .039). However, CD44s expression was not associated with overall survival (P = .529) or disease-free survival (P = .218) by the log-rank test. Moreover, there was no statistical difference in CD44s expression between the primary and recurrent ovarian carcinomas. Our results showed that CD44s expression is not a prognostic predictor in ovarian cancer.

Expression of p16, nm23-H1, E-cadherin, and CD44 gene products and their significance in nasopharyngeal carcinoma

OBJECTIVE

The present study was aimed to determine whether p16/MTS1, nm23-H1, E-cadherin, and CD44 proteins were expressed in nasopharyngeal carcinoma (NPC) and whether those expressions were pathologically significant in the progress of NPC.

METHOD

We examined non-cancerous nasopharyngeal mucosa (20 cases) and NPC (80 cases) using immunohistochemistry with six different types of monoclonal antibodies against p16, nm23-H1, E-cadherin, CD44H, CD44v3, and CD44v6 proteins.

RESULTS

The results showed that 1) the rates of positive p16 protein expression and of preserved E-cadherin protein expression in NPC were significantly lower than those in non-cancerous tissue (P <.01); 2) no significant difference in the rate of positive expression of nm23-H1, CD44H, CD44v3, and CD44v6 proteins were observed between non-cancerous nasopharyngeal mucosa and NPC; 3) no significant difference in the expression of those proteins were found by respective correlation analyses of sex, stage, and size of primary tumor in NPC; and 4) no significant difference in the rates of positive expression of CD44H, CD44v3, and CD44v6 proteins were observed in NPC between with and without lymph node metastasis, indicating that those gene products did not correlate with lymph node metastasis in NPC. However, there were inverse correlations between the expression of p16, nm23-H1, or E-cadherin protein and lymph node metastasis (P <.05), indicating that the expression of p16, nm23-H1, and E-cadherin gene were related to the carcinogenesis and tumor progression of NPC.

CONCLUSION

Detecting the expressions of those gene products may provide clinically valuable information for therapeutic strategy and for predicting the prognosis of patients with NPC.

CD44: physiological expression of distinct isoforms as evidence for organ-specific metastasis formation

Continuous progress has been achieved during recent decades in the therapy of metastasizing malignancies by improving chemotherapeutic strategies and new approaches in radiation therapy. Genetic manipulation of tumor cells and of the tumor fighting immune system is hoped to add significant contributions to curative interventions in disseminated tumors. That we are still far from eradicating death by malignant growth is due ultimately to our limited understanding of the cascade of events resulting in metastasis formation, which until recently was believed to rely on multiple rounds of mutation and selection processes. This implies an individually specific history of each metastatic tumor, which would rule out uniform diagnostic and therapeutic concepts. When it was noted in a rat tumor model that the transfer of cDNA of a single gene, a CD44 variant isoform (CD44v) covering the exons v4-v7, sufficed to initiate metastasis formation of a locally growing tumor, hope was created that a "metastogene" may have been identified. Although the idea of CD44v expression as a unifying concept for tumor progression was not sustained, the discovery of CD44v-initiated metastatic spread allowed a conceptually new hypothesis on tumor progression as a consequence of the reactivation of genetic programs of ontogeny, stem cell differentiation, and/or lymphocyte activation. Since distinct CD44 isoforms play an important role in these processes, unraveling the functions of this family of molecules can indeed provide a cornerstone in the understanding of tumor progression. This article summarizes briefly the present knowledge on known functions of CD44 isoforms with particular focus on parallels between physiological programs and tumor progression.

CD44 expression in normal and inflamed skin

CD44 is the principal cell surface receptor for hyaluronate. In non-inflamed skin, CD44 expression is limited to the cell membrane of eccrine coil cells. The distribution on these cells is asymmetric, with intense staining on the dermal side and little staining on the luminal side of the coil cell. In skin containing a pathologic process, either inflammatory or neoplastic, CD44 expression can be widespread on the membranes of keratinocytes and on infiltrating lymphocytes in the vicinity of the process. Diverse roles have been proposed for CD44 and largely involve aspects of cellular adhesion in one setting or another. CD44 may identify a more mobile, proliferating keratinocyte that is responding to local injury. In eccrine coil, the stable presence of CD44 on the non-luminal surface of secretory cells indicates an undefined function for CD44 in the generation of eccrine sweat.