Of eight Oct4 pseudogenes, six are Oct4A retro-pseudogenes , . in autochthonous cancers without the complication of factors such as pseudogene expression, alternative splicing and antibody specificity. Both the Oct4 and Nanog knockin tumor-bearing mice expressed GFP in blastocysts and Mouse monoclonal to CD235.TBR2 monoclonal reactes with CD235, Glycophorins A, which is major sialoglycoproteins of the human erythrocyte membrane. Glycophorins A is a transmembrane dimeric complex of 31 kDa with caboxyterminal ends extending into the cytoplasm of red cells. CD235 antigen is expressed on human red blood cells, normoblasts and erythroid precursor cells. It is also found on erythroid leukemias and some megakaryoblastic leukemias. This antobody is useful in studies of human erythroid-lineage cell development testes as expected. However, we could find no evidence for expression of the GFP reporter above background levels in tumors using FACS, qPCR and immunohistochemistry. Furthermore, cultivation of Oct4GFP and NanogGFP MMTV-PyMT tumor cells either adherently or as spheroids had no effect on the expression of the GFP reporter. Together these data suggest that Oct4 and Nanog are not expressed in tumor cells that arise in the autochthonous cancer models studied here. Introduction The idea that cancer is driven by a subpopulation of tumor cells with stem cell properties was proposed around 150 years ago . MI 2 During the last decade, the concept that tumor cells are organized in such a hierarchical MI 2 manner has received increasing attention, and evidence for the existence of cancer stem cells (CSCs) has been garnered for both hematopoietic tumors and a variety of solid tumors, including breast, brain, prostate, colon and lung . By definition, cancer stem cells are a subset of tumor cells that are able to self-renew, give rise to heterogeneous progeny, and initiate the growth of new tumors . Stem cell properties such as indefinite growth, growth under non-adherent conditions, drug resistance and asymmetrical division have been attributed to CSCs . These characteristics suggest that targeting of CSCs should be an effective anti-cancer strategy , . Nevertheless, difficulties in isolating CSCs to study their properties have hampered progress in this area. Current marker-based strategies only enrich for CSC subpopulations . Assays used in vitro to study CSCs do not reliably reflect tumor-initiating properties in vivo . There is also increasing evidence that CSC properties are plastic and can be gained or lost, for example in response to microenvironmental cues . Thus new ways of reliably identifying CSCs to facilitate their isolation and characterisation are required. Similarities between embryogenesis and tumorigenesis have long been recognized , , . Key embryonic pathways that regulate self-renewal and differentiation are frequently deregulated during tumor progression , . Moreover, unlimited MI 2 proliferation capacity and self-renewal are typical embryonic stem (ES) cell properties but are also attributed to tumor cells. In ES cells, self-renewal is maintained by the master regulators of pluripotency Oct4, Nanog and Sox2. Oct4 and Nanog are homeodomain transcription factors that are essential for the maintenance of pluripotency and early embryo development. They are highly expressed in pluripotent ES cells and down-regulated upon differentiation , , . In the adult, Oct4 and Nanog expression is normally restricted to the ovary and testis , . Ectopic expression of Oct4 or Nanog in somatic cells results in dedifferentiation, malignant transformation and causes dysplasia in epithelial tissue, demonstrating the oncogenic potential of pluripotency genes , , , . MI 2 Furthermore, ectopic expression of Oct4 in tumor cells results in dedifferentiation and enhanced CSC-like properties such as sphere formation, drug resistance and increased tumorigenicity , , . Consistently, elevated expression of Oct4 and Nanog has been reported in cancer MI 2 cell lines and/or primary cancers from melanoma , , germ cell tumors , , , ,  and cancers of the breast , , , prostate , lung , colorectum  and endometrium , and correlates with.