Epithelial ovarian cancer (EOC) is the fifth-leading cause of cancer death among women in the United States, but its pathogenesis is poorly understood 1-3. Some epithelial cancers are known to occur in transitional zones between two types of epithelium, while others have been shown to originate in epithelial tissue stem cells 4-6. The stem cell niche of the ovarian surface epithelium (OSE), which is ruptured and regenerates during ovulation, has not yet been unequivocally defined. Here we identify the hilum region of the mouse ovary, the transitional/junction area between OSE, mesothelium and tubal (oviductal) epithelium as a previously unrecognized stem cell niche of the OSE. We find that cells of the hilum OSE are slowly-cycling and express stem/progenitor cell markers ALDH1, Lgr5, Lef1, CD133, and CK6b. These cells display long-term stem cell properties ex vivo and in vivo, as shown by our serial sphere generation and by long-term lineage tracing assays. Importantly, the hilum cells exhibit increased transformation potential after inactivation of tumour suppressor genes Trp53 and Rb1, whose pathways are frequently altered in the most aggressive and common type of human EOC, high-grade serous adenocarcinoma 7,8. Our study experimentally supports the notion that susceptibility of transitional zones to malignant transformation may be explained by the presence of stem cell niches in those areas. Identification of a stem cell niche for the OSE may have important implications for understanding EOC pathogenesis.

WNT antagonism displays marked synergy with taxane chemotherapy and reverses taxane-induced enrichment of cancer stem cells.

SUMMARY MicroRNAs of miR-34 family have been originally identified as direct transactivation target of p53 and are putative tumor suppressors. Surprisingly, mice lacking all mir-34 genes show no increase in cancer formation by 18 months of age, hence placing in doubt physiological relevance of previous studies. Here we report that mice with prostate epithelium-specific inactivation of mir-34 and p53 show expansion of prostate stem cell compartment, and develop early invasive adenocarcinomas and high-grade prostatic intraepithelial neoplasia, whereas no such lesions are observed after inactivation of mir-34 or p53 genes alone by 15 months of age. Consistently, combined deficiency for p53 and miR-34 leads to acceleration of MET-dependent growth, self-renewal, and motility of prostate stem/progenitor cells. Our study provides direct genetic evidence that mir-34 genes are bona fide tumor suppressors, and identifies p53/miR-34 joint control of MET expression as a key component of prostate stem cell compartment regulation, aberrations of which may lead to cancer.

During carcinoma formation, cancer cells release various cytokines and growth factors into their surroundings and recruit and reprogram many other types of cells in order to establish a tumor microenvironment. Consequently, the tumor tissues almost always contain a large number of endothelial cells, fibroblasts, and infiltrating inflammatory cells that in turn produce a variety of cytokines. The cytokines produced by these cells have been posited as key factors in modulating immune response either against or in favor of tumorigenesis in the microenvironment. The interactions that take place between immune and cancer cells are complex, involving multiple cascades of cytokines, chemokines, and/or growth factors. In this review, we address the essential pro- and anti-tumorigenic roles of cytokines in the tumor microenvironment. As the interaction of cytokines, growth factors, and cancer cells forms a comprehensive network at the tumor site that is then responsible for the overall progression or rejection of the tumor, the current review links the microenvironment-derived cytokines and growth factors to a number of different kinds of human carcinogenesis models. Multifunctional cytokines, extracellular matrix mediators, and regulatory cytokines in the cancer environment are all shown to be key factors in the different cancer immune-editing systems. The characterization of cytokine networks in various types of cancer cells may yield important information for understanding the immune-related mechanisms of cancer development, and this knowledge may have subsequent application in cancer immunotherapy.

Phenylalanine ammonia-lyase is the first enzyme of general phenylpropanoid pathway. A PAL gene, designated as BoPAL1, was cloned from a Bambusa oldhamii cDNA library. The open reading frame of BoPAL1 was 2,139 bp in size and predicted to encode a 712-amino acid polypeptide. BoPAL1 was the first intronless PAL gene found in angiosperm plant. Several putative cis-acting elements such as P box, GT-1motif, and SOLIPs involved in light responsiveness were found in the 5'-flanking sequence of BoPAL1 which was obtained by TAIL-PCR method. Recombinant BoPAL1 protein expressed in Pichia pastoris was active. The optimum temperature and pH for BoPAL1 activity was 50°C and 9.0, respectively. The molecular mass of recombinant BoPAL1 was estimated as 323 kDa using gel filtration chromatography and the molecular mass of full-length BoPAL was about 80 kDa, indicating that BoPAL1 presents as a homotetramer. The Km and kcat values of BoPAL1 for L-Phe were 1.01 mM and 10.11 s(-1), respectively. The recombinant protein had similar biochemical properties with PALs reported in other plants.