cell-population-analyses-during-skin-carcinogenesis

Cell Population Analyses During Skin Carcinogenesis

Cancer development is  a multiple-step process involving many cell types including cancer precursor  cells, immune cells, fibroblasts and endothelial ...

Indiana University

The genotypes and protein polymorphisms of milk epithelial mucin (MUC1) were analyzed by touch-down PCR and SDS-PAGE respectively using blood samples and milk collected from 50 lactating yaks. A total of seven alleles were revealed, namely A, B, C, D, E, F, and G, and the corresponding number of repetitive units of variable number tandem repeat (VNTR) in MUC1 gene were 21, 20, 19, 18, 17, 16, and 15, respectively. Fifteen genotypes of MUC1 were observed in yaks. The genotypes of MUC1 gene matched completely to the phenotypes of milk MUC1 in each individual. This study demonstrated that the yak MUC1 exhibits abundant polymorphisms in both its gene and protein, and the polymorphisms are due to the expression of VNTR in MUC1 gene. The possible cluster of the VNTR was also discussed in different ruminants.

Analysis of Yak MUC1 Protein Polymorphisms and the Corresponding VNTR Structure.

The establishment of agricultural economies based upon domestic animals began independently in many parts of the world and led to both increases in human population size and the migration of people carrying domestic plants and animals. The precise circumstances of the earliest phases of these events remain mysterious given their antiquity and the fact that subsequent waves of migrants have often replaced the first. Through the use of more than 1,500 modern (including 151 previously uncharacterized specimens) and 18 ancient (representing six East Asian archeological sites) pig (Sus scrofa) DNA sequences sampled across East Asia, we provide evidence for the long-term genetic continuity between modern and ancient Chinese domestic pigs. Although the Chinese case for independent pig domestication is supported by both genetic and archaeological evidence, we discuss five additional (and possibly) independent domestications of indigenous wild boar populations: one in India, three in peninsular Southeast Asia, and one off the coast of Taiwan. Collectively, we refer to these instances as "cryptic domestication," given the current lack of corroborating archaeological evidence. In addition, we demonstrate the existence of numerous populations of genetically distinct and widespread wild boar populations that have not contributed maternal genetic material to modern domestic stocks. The overall findings provide the most complete picture yet of pig evolution and domestication in East Asia, and generate testable hypotheses regarding the development and spread of early farmers in the Far East.

Patterns of East Asian pig domestication, migration, and turnover revealed by modern and ancient DNA.

Hedgehog (Hh) signaling, via the key signal transducer Smoothened (SMO) and Gli transcription factors, is essential for embryonic development and carcinogenesis. At present, the molecular mechanism of Hh signaling-mediated carcinogenesis is not completely understood. Using a mouse model (K14cre/R26SmoM2) of SMO-mediated basal cell carcinoma development, we identified TGFÎ²2 as a major Hh-regulated gene. TGFÎ²2 expression was high in the keratinocytes, with activated TGFÎ² signaling (indicated by elevated expression of phosphorylated SMAD2/3) detected in both tumor and stroma. The significance of TGFÎ² signaling for SMO function was demonstrated in two assays. Down-regulation of TGFÎ²2 expression prevented Hh signaling-dependent osteoblast differentiation and motor neuron differentiation. Furthermore, inhibition of TGFÎ² signaling by TGFÎ² receptor I inhibitor SD208 significantly reduced tumor area in K14cre/R26SmoM2 mice. Tumor shrinkage in mice was associated with an increased number of lymphocytes, suggesting an immune suppression role of TGFÎ² signaling. The relevance of our results to human cancer is reflected by the fact that human basal cell carcinomas, which almost always harbor activated Hh signaling, have activated TGFÎ² signaling, as indicated by high levels of phosphorylated SMAD2 and SMAD3 in tumor and stroma. Together, our data indicate that TGFÎ² signaling is critical for Hh signaling-mediated carcinogenesis.

Requirement of TGFbeta signaling for SMO-mediated carcinogenesis.

Human fatty acid synthase (FASN) is a homo-dimeric protein with multi-enzymatic activity responsible for the synthesis of palmitate. FASN expression has been found to be up-regulated in multiple types of human cancers and its expression correlates with poor prognosis possibly by causing treatment resistance. In this study, we tested if FASN expression is up-regulated in human pancreatic cancers and if its higher expression level in pancreatic cancers causes intrinsic resistance to gemcitabine and radiation. We found that FASN expression is significantly up-regulated in human pancreatic cancer tissues without any correlation to age, sex, race, and tumor stage. Knocking down or over-expressing FASN significantly down- or up-regulate resistance of pancreatic cancer cell lines to both gemcitabine and radiation treatments. These findings imply that the elevated FASN expression in pancreatic cancers may contribute to unsuccessful treatments of pancreatic cancers by causing intrinsic resistance to both chemotherapy and radiation therapy.

Role of fatty acid synthase in gemcitabine and radiation resistance of pancreatic cancers.

The link of hedgehog (Hh) signaling activation to human cancer and synthesis of a variety of Hh signaling inhibitors raise great expectation that inhibiting Hh signaling may be effective in human cancer treatment. Cyclopamine (Cyc), an alkaloid from the Veratrum plant, is a specific natural product inhibitor of the Hh pathway that acts by targeting smoothened (SMO) protein. However, its poor solubility, acid sensitivity, and weak potency relative to other Hh antagonists prevent the clinical development of Cyc as a therapeutic agent. Here, we report properties of cyclopamine tartrate salt (CycT) and its activities in Hh signaling-mediated cancer in vitro and in vivo. Unlike Cyc, CycT is water soluble (5-10 mg/mL). The median lethal dose (LD50) of CycT was 62.5 mg/kg body weight compared to 43.5 mg/kg for Cyc, and the plasma half-life (T1/2) of CycT was not significantly different from that of Cyc. We showed that CycT had a higher inhibitory activity for Hh signaling-dependent motor neuron differentiation than did Cyc (IC50 = 50 nmol/L for CycT vs. 300 nmol/L for Cyc). We also tested the antitumor effectiveness of these Hh inhibitors using two mouse models of basal cell carcinomas (K14cre:Ptch1(neo/neo) and K14cre:SmoM2(YFP)). After topical application of CycT or Cyc daily for 21 days, we found that all CycT-treated mice had tumor shrinkage and decreased expression of Hh target genes. Taken together, we found that CycT is an effective inhibitor of Hh signaling-mediated carcinogenesis.

Tumor shrinkage by cyclopamine tartrate through inhibiting hedgehog signaling.

Activation of the Hedgehog (Hh) pathway is known to drive development of basal cell carcinoma and medulloblastomas and to associate with many other types of cancer, but the exact molecular mechanisms underlying the carcinogenesis process remain elusive. We discovered that skin tumors derived from epidermal expression of oncogenic Smo, SmoM2, have elevated levels of IL-11, IL-11RÎ±, and STAT3 phosphorylation at Tyr(705). The relevance of our data to human conditions was reflected by the fact that all human basal cell carcinomas examined have detectable STAT3 phosphorylation, mostly in keratinocytes. The functional relevance of STAT3 in Smo-mediated carcinogenesis was revealed by epidermal specific knockout of STAT3. We showed that removal of STAT3 from mouse epidermis dramatically reduced SmoM2-mediated cell proliferation, leading to a significant decrease in epidermal thickness and tumor development. We also observed a significant reduction of epidermal stem/progenitor cell population and cyclin D1 expression in mice with epidermis-specific knockout of STAT3. Our evidence indicates that STAT3 signaling activation may be mediated by the IL-11/IL-11RÎ± signaling axis. We showed that tumor development was reduced after induced expression of SmoM2 in IL-11RÎ± null mice. Similarly, neutralizing antibodies for IL-11 reduced the tumor size. In two Hh-responsive cell lines, ES14 and C3H10T1/2, we found that addition of Smo agonist purmorphamine is sufficient to induce STAT3 phosphorylation at Tyr(705), but this effect was abolished after IL-11RÎ± down-regulation by shRNAs. Taken together, our results support an important role of the IL-11RÎ±/STAT3 signaling axis for Hh signaling-mediated signaling and carcinogenesis.

Article	Year
Analysis of Yak MUC1 Protein Polymorphisms and the Corresponding VNTR Structure. Animal biotechnology\| PubMed ID: 19937497	2009
Patterns of East Asian pig domestication, migration, and turnover revealed by modern and ancient DNA. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 20404179	2010
Requirement of TGFbeta signaling for SMO-mediated carcinogenesis. The Journal of biological chemistry\| PubMed ID: 20858897	2010
Role of fatty acid synthase in gemcitabine and radiation resistance of pancreatic cancers. International journal of biochemistry and molecular biology\| PubMed ID: 21331354	2011
Tumor shrinkage by cyclopamine tartrate through inhibiting hedgehog signaling. Chinese journal of cancer\| PubMed ID: 21718593	2011
A role for transcription factor STAT3 signaling in oncogene smoothened-driven carcinogenesis. The Journal of biological chemistry\| PubMed ID: 22992748	2012

Qipeng Fan

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