The impact of EpCAM expression on response to chemotherapy and clinical outcomes in patients with epithelial ovarian cancer.

Epithelial ovarian cancer is a highly lethal malignancy; moreover, overcoming chemoresistance is the major challenging in treating ovarian cancer patients. The cancer stem cell (CSC) hypothesis considers CSCs to be the main culprits in driving tumor initiation, metastasis, and resistance to conventional therapy. Although growing evidence suggest that CSCs are responsible for chemoresistance, the contribution of CSC marker EpCAM to resistance to chemotherapy remains unresolved.Here we have demonstrated that ovarian cancers containing high levels of EpCAM have a significantly much lower probability of achieving overall responsive rates after first-line chemotherapy. In addition, multivariate analysis revealed that EpCAM expression is an independent risk factor for chemoresistance, indicating that EpCAM expression is a predictive biomarker of chemotherapeutic response. Consistent with these clinical observations, in vitro assays, we found that the subpopulation of EpCAM-positive ovarian cancer cells shows a significantly higher viability compared with EpCAM-negative cells in response to cisplatin treatment by preventing chemotherapy-induced apoptosis, which is regulated by EpCAM-Bcl-2 axis. Furthermore, in an in vivo mouse model, platinum agents preferentially eliminated EpCAM-negative cells in comparison with EpCAM-positive cells, suggesting that the remaining subpopulation of EpCAM-positive cells contributes to tumor recurrence after chemotherapy. Finally, we also found that an increased expression of EpCAM is associated with poor prognosis in ovarian cancer patients.Our findings highlight the clinical significance of EpCAM in the resistance to chemotherapy and provide a rationale for EpCAM-targeted therapy to improve chemoresistance. Targeting EpCAM should be a promising approach to effectively extirpate the CSCs as the putative root of ovarian cancer.

CD44 Variant 6 as a Predictive Biomarker for Distant Metastasis in Patients With Epithelial Ovarian Cancer.

OBJECTIVE: To investigate the role of cancer stem cell marker CD44 variant 6 in the development of distant metastasis in patients with epithelial ovarian cancer. METHODS: A retrospective cohort study was performed in 186 patients who underwent surgery for ovarian cancer from 2005 to 2013 at the Kumamoto University Hospital. The association between the expression of CD44 variant 6 and distant metastasis was evaluated based on a large-scale immunohistochemical analysis. Primary ovarian tumors that contained at least 10% CD44 variant 6-positive cancer cells were categorized as CD44v6-high (n=53), and the tumors that contained less than 10% CD44 variant 6-positive cells were categorized as CD44v6-low (n=133). Distant metastasis-free survival was compared between the CD44v6-high and -low groups. Multivariate analysis was performed to estimate the influence of various clinicopathologic factors on the development of distant metastasis. RESULTS: At the time of ovarian cancer diagnosis, distant metastasis occurred in 13 of 53 patients (24.5%) in the CD44v6-high group and 17 of 133 patients (12.8%) in the CD44v6-low group (P=.049). The median metastasis-free survival after stage I-III ovarian cancer diagnosis was 19.5 months (range 11-55 months) in the CD44v6-high group (n=40) and 39.5 months (range 22-57 months) in the CD44v6-low group (n=116) (P=.071). Multivariate analysis demonstrated that CD44 variant 6 expression was an independent risk factor for distant metastatic recurrence (hazard ratio 4.09, 95% confidence interval 1.29-12.98; P=.017). CONCLUSION: CD44 variant 6 represents an important predictor of distant metastasis and CD44 variant 6-positive ovarian cancer cells play a crucial role in the formation of distant metastases in patients with ovarian cancer.

CD44 variant 6 is correlated with peritoneal dissemination and poor prognosis in patients with advanced epithelial ovarian cancer.

Cancer stem cells (CSCs) drive tumor initiation and metastasis in several types of human cancer. However, the contribution of ovarian CSCs to peritoneal metastasis remains unresolved. The cell adhesion molecule CD44 has been identified as a major marker for CSCs in solid tumors, including epithelial ovarian cancer. CD44 exists as a standard form (CD44s) and also as numerous variant isoforms (CD44v) generated by alternative mRNA splicing. Here we show that disseminated ovarian tumors in the pelvic peritoneum contain highly enriched CD44v6-positive cancer cells, which drive tumor metastasis and are responsible for tumor resistance to chemotherapy. Clinically, an increased number of CD44v6-positive cancer cells in primary tumors was associated with a shortened overall survival in stage III-IV ovarian cancer patients. Furthermore, a subpopulation of CD44v6-positive cancer cells manifested the ability to initiate tumor metastasis in the pelvic peritoneum in an in vivo mouse model, suggesting that CD44v6-positive cells show the potential to serve as metastasis-initiating cells. Thus, the peritoneal disseminated metastasis of epithelial ovarian cancer is initiated by the CD44v6-positive subpopulation, and CD44v6 expression is a biomarker for the clinical outcome of advanced ovarian cancer patients. Given that a distinct subpopulation of CD44v6-positive cancer cells plays a critical role in peritoneal metastasis, definitive treatment should target this subpopulation of CD44v6-positive cells in epithelial ovarian cancer.

Mesenchymal stem cell transplantation modulates neuroinflammation in focal cerebral ischemia: contribution of fractalkine and IL-5.

Mesenchymal stem cells (MSCs) are reported to possess immunomodulatory properties. Previous reports have demonstrated the beneficial effects of MSC-transplantation in focal cerebral ischemia animal models. In this study, we have investigated the neuroimmunomodulatory functions of human MSCs, transplanted in a rat focal ischemia model of transient middle cerebral artery occlusion (MCAO). Our results revealed that in a human mesenchymal stem cell line, B10 cell transplantation decreased the accumulation of Iba-1(+) microglia and GFAP(+) astrocytes, and inhibited proinflammatory gene expression in the core and ischemic border zone (IBZ). Among the proinflammatory genes iNOS, which was expressed in microglia/macrophage, was persistently inhibited up to 7days after MCAO. In vivo laser capture microdissection and double immunofluorescence staining, and in vitro B10 cell culture experiments showed that, in inflammatory conditions, B10 cells expressed cytokines and growth factors including IL-5, fractalkine, IGF-1, GDNF and VEGF. Fractalkine and IL-5 inhibited cytokine-induced proinflammatory gene expression including iNOS in a human microglia cell line. Thus, our results demonstrate that MSC transplantation suppresses MCAO focal ischemia-induced inflammation, possibly through expression of fractalkine and IL-5.

Human microglia transplanted in rat focal ischemia brain induce neuroprotection and behavioral improvement.

BACKGROUND AND PURPOSE: Microglia are resident immunocompetent and phagocytic cells of central nervous system (CNS), which produce various cytokines and growth factors in response to injury and thereby regulate disease pathology. The purpose of this study is to investigate the effects of microglial transplantation on focal cerebral ischemia model in rat. METHODS: Transient middle cerebral artery occlusion (MCAO) in rats was induced by the intraluminal filament technique. HMO6 cells, human microglial cell line, were transplanted intravenously at 48 hours after MCAO. Functional tests were performed and the infarct volume was measured at 7 and 14 days after MCAO. Migration and cell survival of transplanted microglial cells and host glial reaction in the brain were studied by immunohistochemistry. Gene expression of neurotrophic factors, cytokines and chemokines in transplanted cells and host rat glial cells was determined by laser capture microdissection (LCM) and quantitative real time-PCR. RESULTS: HMO6 human microglial cells transplantation group demonstrated significant functional recovery compared with control group. At 7 and 14 days after MCAO, infarct volume was significantly reduced in the HMO group. In the HMO6 group, number of apoptotic cells was time-dependently reduced in the infarct core and penumbra. In addition, number of host rat microglia/macrophages and reactive astrocytes was significantly decreased at 7 and 14 days after MCAO in the penumbra. Gene expression of various neurotrophic factors (GDNF, BDNF, VEGF and BMP7) and anti-inflammatory cytokines (IL4 and IL5) was up-regulated in transplanted HMO6 cells of brain tissue compared with those in culture. The expression of GDNF and VEGF in astrocytes in penumbra was significantly up-regulated in the HMO6 group. CONCLUSIONS: Our results indicate that transplantation of HMO6 human microglial cells reduces ischemic deficits and apoptotic events in stroke animals. The results were mediated by modulation of gliosis and neuroinflammation, and neuroprotection provided by neurotrophic factors of endogenous and transplanted cells-origin.

Transplantation of human mesenchymal stem cells promotes functional improvement and increased expression of neurotrophic factors in a rat focal cerebral ischemia model.

Previous studies have suggested that intravenous transplantation of mesenchymal stem cells (MSCs) in rat ischemia models reduces ischemia-induced brain damage. Here, we analyzed the expression of neurotrophic factors in transplanted human MSCs and host brain tissue in rat middle cerebral artery occlusion (MCAO) ischemia model. At 1 day after transient MCAO, 3 x 10(6) immortalized human MSC line (B10) cells or PBS was intravenously transplanted. Behavioral tests, infarction volume, and B10 cell migration were investigated at 1, 3, 7, and 14 days after MCAO. The expression of endogenous (rat origin) and exogenous (human origin) neurotrophic factors and cytokines was evaluated by quantitative real-time RT-PCR and Western blot analysis. Compared with PBS controls, rats receiving MSC transplantation showed improved functional recovery and reduced brain infarction volume at 7 and 14 days after MCAO. In MSC-transplanted brain, among many neurotrophic factors, only human insulin-like growth factor 1 (IGF-1) was detected in the core and ischemic border zone at 3 days after MCAO, whereas host cells expressed markedly higher neurotrophic factors (rat origin) than control rats, especially vascular endothelial growth factor (VEGF) at 3 days and epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) at 7 days after MCAO. Intravenously transplanted human MSCs induced functional improvement, reduced infarct volume, and neuroprotection in ischemic rats, possibly by providing IGF-1 and inducing VEGF, EGF, and bFGF neurotrophic factors in host brain.

Microglia transplantation attenuates white matter injury in rat chronic ischemia model via matrix metalloproteinase-2 inhibition.

Chronic cerebral ischemia is thought to induce white matter lesions (WMLs), which contribute to subcortical vascular dementia. Although glial activation and protease upregulation are believed to modify WML pathology, effective therapy remains elusive. Here, we compare the efficacy of microglial cell transplantation and mesenchymal stem cell (MSC) transplantation in protecting against WML development in a chronic cerebral hypoperfusion rat model. A microglial cell line (HMO6), MSC cell line (B10) or vehicle (phosphate-buffered saline; PBS) was intravenously injected, and the appearance and severity of WMLs were evaluated. Transplanted HMO6 and B10 cells migrated to sites of WMLs, including the corpus callosum (CC) and caudoputamen (CP), reduced the severity of WMLs, and inhibited the accumulation and activation of microglia and astrocytes. Transplantation of both cell types reduced the level of matrix metalloproteinase (MMP)-2 mRNA in microglia of the CC. MMP-2 protein level and activity were also both greatly reduced in the same region. Our results indicate that transplantation of either microglial cells or mesenchymal stem cells could inhibit chronic cerebral ischemia-induced WML formation by decreasing MMP-2 expression in microglia and decreasing MMP-2 activity in the CC region.