Prognostic value of CD44v9 expression in human cancers: A systematic review and meta-analysis

BACKGROUND

The prognostic significance of CD44 variant-9 (CD44v9) expression in human cancers has been investigated in several studies, however, definite conclusion has not be reached. The aim of this systematic review and meta-analysis was to evaluate the prognostic significance of CD44v9 expression in various cancers.

METHODS

Three common databases were searched and retrieved studies were assessed using the inclusion and exclusion criteria. The further analyses for overall survival (OS), recurrence-free survival (RFS), and clinicopathological parameters were performed.

RESULTS

Fifteen studies containing 1633 cancer patients were included into this research. Patients with positive CD44v9 expression tended to have shorter OS (hazard ratio [HR] = 1.93, 95% confidence interval [CI] = 1.48-2.52, P < .01) and RFS (HR = 3.60, 95% CI = 1.52-8.53, P < .01) when compared with patients with negative CD44v9 expression. Positive CD44v9 expression was associated with larger tumor size (P = .04), deeper tumor invasion (P < .01), earlier lymph node metastasis (P < .01), and more advanced clinical stage (P < .01) when compared with negative CD44v9 expression.

CONCLUSION

Positive CD44v9 expression predicted worse prognosis in human cancers compared with negative CD44v9 expression. CD44v9 expression could serve as a prognostic factor of human cancers.

Concise Review: Emerging Role of CD44 in Cancer Stem Cells: A Promising Biomarker and Therapeutic Target

The reception and integration of the plethora of signals a cell receives from its microenvironment determines the cell's fate. CD44 functions as a receptor for hyaluronan and many other extracellular matrix components, as well as a cofactor for growth factors and cytokines, and thus, CD44 is a signaling platform that integrates cellular microenvironmental cues with growth factor and cytokine signals and transduces signals to membrane-associated cytoskeletal proteins or to the nucleus to regulate a variety of gene expression levels related to cell-matrix adhesion, cell migration, proliferation, differentiation, and survival. Accumulating evidence indicates that CD44, especially CD44v isoforms, are cancer stem cell (CSC) markers and critical players in regulating the properties of CSCs, including self-renewal, tumor initiation, metastasis, and chemoradioresistance. Furthermore, there is ample evidence that CD44, especially CD44v isoforms, are valuable prognostic markers in various types of tumors. Therefore, therapies that target CD44 may destroy the CSC population, and this holds great promise for the cure of life-threatening cancers. However, many challenges remain to determining how best to use CD44 as a biomarker and therapeutic target. Here we summarize the current findings concerning the critical role of CD44/CD44v in the regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer. We also discuss the current challenges and future directions that may lead to the best use of CD44/CD44v for clinical applications.

SIGNIFICANCE

Mounting evidence indicates that cancer stem cells (CSCs) are mainly responsible for cancer aggressiveness, drug resistance, and tumor relapse. CD44, especially CD44v isoforms, have been identified as CSC surface markers for isolating and enriching CSCs in different types of cancers. The current findings concerning the critical role of CD44/CD44v in regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer are summarized. The current challenges and future directions that may lead to best use of CD44/CD44v for clinical applications are also discussed.

A survey of immunohistochemical biomarkers for basal-like breast cancer against a gene expression profile gold standard

Gene expression profiling of breast cancer delineates a particularly aggressive subtype referred to as 'basal-like', which comprises ∼15% of all breast cancers, afflicts younger women and is refractory to endocrine and anti-HER2 therapies. Immunohistochemical surrogate definitions for basal-like breast cancer, such as the clinical ER/PR/HER2 triple-negative phenotype and models incorporating positive expression for CK5 (CK5/6) and/or EGFR are heavily cited. However, many additional biomarkers for basal-like breast cancer have been described in the literature. A parallel comparison of 46 proposed immunohistochemical biomarkers of basal-like breast cancer was performed against a gene expression profile gold standard on a tissue microarray containing 42 basal-like and 80 non-basal-like breast cancer cases. Ki67 and PPH3 were the most sensitive biomarkers (both 92%) positively expressed in the basal-like subtype, whereas CK14, IMP3 and NGFR were the most specific (100%). Among biomarkers surveyed, loss of INPP4B (a negative regulator of phosphatidylinositol signaling) was 61% sensitive and 99% specific with the highest odds ratio (OR) at 108, indicating the strongest association with basal-like breast cancer. Expression of nestin, a common marker of neural progenitor cells that is also associated with the triple-negative/basal-like phenotype and poor breast cancer prognosis, possessed the second highest OR at 29 among the 46 biomarkers surveyed, as well as 54% sensitivity and 96% specificity. As a positively expressed biomarker, nestin possesses technical advantages over INPP4B that make it a more ideal biomarker for identification of basal-like breast cancer. The comprehensive immunohistochemical biomarker survey presented in this study is a necessary step for determining an optimized surrogate immunopanel that best defines basal-like breast cancer in a practical and clinically accessible way.

Serum CD44 levels and overall survival in patients with HER2-positive breast cancer

CD44 is an adhesion molecule involved in tumor cell invasion and metastasis. The function of CD44 in breast cancer is not understood completely, or is its role as a predictive or prognostic factor. In this study, we tested for the hypothesis that the concentration of soluble CD44 (sCD44) in serum is correlated with clinicopathological factors, especially HER2, and survival in patients with breast cancer. We retrospectively identified 110 patients with breast cancer who had been treated at The University of Texas MD Anderson Cancer Center (MDACC) from September 2001 to May 2004. Sera were collected before definitive surgery in patients with stage I or II breast cancer, before initiation of neoadjuvant chemotherapy (if indicated) for patients with stage I-III breast cancer, and before initiation of systemic therapy in patients with stage IV breast cancer. sCD44 levels were determined using an enzyme-linked immunosorbent assay. The median age at diagnosis was 51 years (range, 28.6-87.1 years). sCD44 concentration was correlated with tumor stage (P = 0.0308). sCD44 serum concentration did not predict pathological response in patients treated with neoadjuvant chemotherapy. Among patients with distant metastases, sCD44 levels were significantly higher in patients with liver involvement than in patients with metastases at other sites. The overall survival rate did not differ between patients with high sCD44 concentration and patients with low sCD44 concentration. However, sCD44 concentration was a significant predictor of overall survival for patients with HER2-positive breast cancer, while no difference in overall survival rates was observed in patients with HER2-negative breast cancer. To the best of our knowledge, this is the first study to show an association between circulating sCD44 levels and survival in HER2-positive breast cancer patients. Our results suggest a role for sCD44 as a prognostic marker. Furthermore, sCD44 level may offer a new clinical therapeutic target in HER2-positive breast cancer.