Malignant gliomas are lethal cancers that display striking cellular heterogeneity. A highly tumorigenic glioma tumor subpopulation, termed cancer stem cells or tumor-initiating cells, promotes therapeutic resistance and tumor angiogenesis. Therefore, targeting cancer stem cells may improve patient survival. We interrogated the role of a neuronal cell adhesion molecule, L1CAM, in glioma stem cells as L1CAM regulates brain development and is expressed in gliomas. L1CAM + and CD133 + cells cosegregated in gliomas, and levels of L1CAM were higher in CD133 + glioma cells than normal neural progenitors. Targeting L1CAM using lentiviral-mediated short hairpin RNA (shRNA) interference in CD133 + glioma cells potently disrupted neurosphere formation, induced apoptosis, and inhibited growth specifically in glioma stem cells. We identified a novel mechanism for L1CAM regulation of cell survival as L1CAM knockdown decreased expression of the basic helix-loop-helix transcription factor Olig2 and upregulated the p21 WAF1/CIP1 tumor suppressor in CD133 + glioma cells. To determine if targeting L1CAM was sufficient to reduce glioma stem cell tumor growth in vivo, we targeted L1CAM in glioma cells before injection into immunocompromised mice or directly in established tumors. In each glioma xenograft model, shRNA targeting of L1CAM expression in vivo suppressed tumor growth and increased the survival of tumorbearing animals. Together, these data show that L1CAM is required for maintaining the growth and survival of CD133 + glioma cells both in vitro and in vivo, and L1CAM may represent a cancer stem cell-specific therapeutic target for improving the treatment of malignant gliomas and other brain tumors. [Cancer Res 2008;68(15):6043-8]

In ovarian cancer, CD44+/CD117+ stem cells, also known as cancer‐initiating cells (CICs), are highly proliferative, have a low degree of differentiation, and are resistant to chemotherapeutics. Therefore, the CD44+/CD117+ subpopulation is thought to be an important target for novel therapeutic strategies. In this study, we investigated the role of microRNA‐199a (miR‐199a) in ovarian cancer stem cells. Luciferase reporter gene assays confirmed that miR‐199a targets CD44 via an miR‐199a‐binding site in the 3′‐UTR. CD44+/CD117+ ovarian CICs were enriched from human primary ovarian tumor tissues and confirmed by flow cytometric sorting. miR‐199a was cloned and transfected into ovarian CICs. CD44 mRNA and protein expression was significantly decreased in miR‐199a‐transfected ovarian CICs as compared with miR‐199a mutant‐transfected and untransfected cells. Cell cycle analysis, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium bromide proliferation assays, the colony formation assay and the transwell migration assay indicated that miR‐199a significantly affected cell cycle regulation and suppressed the proliferation and invasive capacity of ovarian CICs in vitro. miR‐199a significantly increased the chemosensitivity of ovarian CICs to cisplatin, pacitaxel, and adriamycin, and reduced mRNA expression of the multidrug resistance gene ABCG2 as compared with miR‐199a mutant‐transfected and untransfected cells. The expression of stemness markers was also significantly reduced in miR‐199a‐transfected CICs as compared with miR‐199a mutant‐transfected and untransfected ovarian cells. Furthermore, xenograft experiments confirmed that miR‐199a suppressed the growth of xenograft tumors formed by ovarian CICs in vivo. Thus, expression of endogenous mature miR‐199a may prevent tumorigenesis in human ovarian cancer by regulating expression of its target gene CD44.

Although ginseng and related herbs have a long history of utility for various health benefits, their application in cancer therapy and underlying mechanisms of action are not fully understood. Our recent work has shown that 20(S)-25-methoxyl-dammarane-3β, 12β, 20-triol (25-OCH3-PPD), a newly identified ginsenoside from Panax notoginseng, exerts activities against a variety of cancer cells in vitro and in vivo. This study was designed to investigate its anti-breast cancer activity and the underlying mechanisms of action. We observed that 25-OCH3-PPD decreased the survival of breast cancer cells by induction of apoptosis and G1 phase arrest and inhibited the growth of breast cancer xenografts in vivo. We further demonstrated that, in a dose- and time-dependent manner, 25-OCH3-PPD inhibited MDM2 expression at both transcriptional and post-translational levels in human breast cancer cells with various p53 statuses (wild type and mutant). Moreover, 25-OCH3-PPD inhibited in vitro cell migration, reduced the expression of epithelial-to-mesenchymal transition (EMT) markers, and prevented in vivo metastasis of breast cancer. In summary, 25-OCH3-PPD is a potential therapeutic and anti-metastatic agent for human breast cancer through down-regulating MDM2. Further preclinical and clinical development of this agent is warranted.

Chemokines and their receptors show a strong relationship with poor clinical outcomes in various cancers. However, their underlying mechanisms remain to be fully elucidated. In our research, we found C-C chemokine receptor 7 (CCR7) and its ligand chemokine ligand 21 (CCL21) were abnormally abundant in oral squamous cell carcinoma (OSCC) tissues, and CCR7 expression was correlated with poor prognosis of OSCC. After exogenous CCL21 stimulation, epithelial-mesenchymal transition (EMT) was promoted in OSCC cells, and cancer stem cell-related markers CD133, CD44, BMI1, ALDH1A1, and OCT4 increased. The migration, invasion, tumorsphere formation, and colony formation abilities of OSCC cells were enhanced, indicating that the stemness of OSCC cells was also improved. The knockdown and overexpression of CCR7 efficiently affected the CCL21-induced EMT and stemness of OSCC cells. When treated with CCL21, the phospho-JAK2 and phospho-STAT3 markedly increased. The inhibitor of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) significantly suppressed CCL21-induced EMT and stemness of OSCC cells. In conclusion, CCL21/CCR7 axis regulated EMT progress and promoted the stemness of OSCC by activating the JAK2/STAT3 signaling pathway. CCL21/CCR7 might be an effective target for OSCC prevention and treatment.

No abstract

MicroRNAs (miRNAs) may function as oncogenes or tumor suppressors. Here, we identified that miR-590-5p was up-regulated in human cervical cancer. Over-expression of miR-590-5p promoted cervical cancer cell growth, cell cycle and invasion via Growth curve, Colony formation, FACS and Transwell assays in HeLa and C33A cell lines. Subsequently, CHL1 was identified as a potential miR-590-5p target by bioinformatics analysis. Moreover, we showed that CHL1 was negatively regulated by miR-590-5p at the posttranscriptional level, via a specific target site within the 3'UTR by luciferase reporter assay. Furthermore, the mRNA and protein levels of CHL1 in cervical cancer cells were downregulated by miR-590-5p. And we identified the cell phenotype altered by miR-590-5p can be rescued by over-expression of CHL1. Therefore, our findings suggest that miR-590-5p acts as an oncogene by targeting the CHL1 gene and promotes cervical cancer proliferation. The findings of this study contribute to current understanding of the functions of miR-590-5p in cervical cancer.

No abstract

Cancer stem cells are enriched in triple-negative breast cancer (TNBC) tumor tissues, which present strong capacities of proliferation and tumorigenicity. The present study detected the distribution of cancer stem cell markers cluster of differentiation (CD)44/CD24 and analyzed the clinical outcomes of different CD44/CD24 phenotypes in patients with TNBC. Multivariate Cox regression analyses were performed with regard to the prognostic value of cancer stem cell markers CD44/CD24, aldehyde dehydrogenase 1 and other baseline clinical characteristics, including tumor size, lymph node involved, adjuvant chemotherapy, Ki-67, breast cancer susceptibility gene 1, cellular tumor antigen p53, vimentin and basal-like status. The multivariate analyses showed that three of these factors, CD44/CD24 phenotype, basal-like status and number of lymph nodes involved, had an impact on overall survival. Furthermore, patients with CD44+/CD24− phenotype, basal-like tumors and ≥4 lymph nodes involved had a significantly worse prognosis. The expression of CD44 and CD24 was detected by double-staining immunohistochemistry, which can locate cancer stem cells individually. Overall, the present results indicated that CD44/CD24 status evaluated by double-staining immunohistochemistry constitutes an independent prognostic factor for TNBC.