Prognostic value of OCT4A and SPP1C transcript variant co-expression in early-stage lung adenocarcinoma.

BACKGROUND: Octamer-binding transcription factor 4A (OCT4A) is essential for cell pluripotency and reprogramming both in humans and mice. To date, however, the function of human OCT4 in somatic and/or tumour tissues is largely unknown. METHODS: RT-PCR was used to identify full-length splice forms of OCT4 transcripts in normal and cancer cells. A FLAG-tagged OCT4 genomic transgene was used to identify OCT4-positive cancer cells. A potential role for OCT4 in somatic cancer cells was examined by cell ablation of OCT4-positive cells using promoter-driven diphtheria toxin A. OCT4 and secreted phosphoprotein 1 (SPP1) transcripts in early-stage lung adenocarcinoma tumours were analysed and compared with pathohistological features. RESULTS: The results show that, unlike in murine cells, OCT4A and OCT4B variants are transcribed in both human cancer cells and in adult tissues such as lung, kidney, uterus, breast, and eye. We found that OCT4A and SPP1C are co-expressed in highly aggressive human breast, endometrial, and lung adenocarcinoma cell lines, but not in mesothelial tumour cell lines. Ablation of OCT4-positive cells in lung adenocarcinoma cells significantly decreased cell migration and SPP1C mRNA levels. The OCT4A/SPP1C axis was found in primary, early-stage, lung adenocarcinoma tumours. CONCLUSIONS: Co-expression of OCT4 and SPP1 may correlate with cancer aggressiveness, and the OCT4A/SPP1C axis may help identify early-stage high-risk patients with lung adenocarcinoma. Contrary to the case in mice, our data strongly suggest a critical role for OCT4A and SPP1C in the development and progression of human epithelial cancers.

Conclusive Evidence for OCT4 Transcription in Human Cancer Cell Lines: Possible Role of a Small OCT4-Positive Cancer Cell Population.

The role of octamer-binding transcription factor 4 (OCT4) in human cancer is still debated. Although many studies have been published on human OCT4, determining which of the findings are accurate or which are false-positives is currently challenging. We thus developed the most reliable method to date for highly specific and comprehensive detection of genuine OCT4-transcript variants without false-positive results. Our results provided clear evidence that the transcripts of OCT4A, OCT4B, OCT4B1, and other novel splicing variants are indeed present in many cancer cell lines, but are rarely detected in normal tissue-derived differentiated cells. Using the tagged genomic transgene, we then verified endogenous OCT4A translation in cancer cell subpopulations. Moreover, analysis of possible other protein isoforms by enforced expression of OCT4B variants showed that the B164 isoform, designated human OCT4C, is preferentially produced in a cap-dependent manner. We confirmed that the OCT4C isoform, similar to OCT4A, can transform non-tumorigenic fibroblasts in vitro. Finally, ablation of OCT4-positive cells using promoter-driven diphtheria toxin A in high malignant cancer cells caused a significant decrease in migration and Matrigel invasion. These findings strongly suggest a significant contribution of OCT4 to the phenotype of human cancer cells. Stem Cells 2018.

Immediate differentiation of neuronal cells from stem/progenitor-like cells in the avian iris tissues.

A simple culture method that was recently developed in our laboratory was applied to the chick iris tissues to characterize neural stem/progenitor-like cells. Iris tissue is a non-neuronal tissue and does not contain any neuronal cells. In the present study we isolated iris tissues from chick embryos just prior to hatching. The isolated iris pigmented epithelium (IPE) or the stroma was embedded in Matrigel and cultured in Dulbecco's MEM supplemented with either fetal bovine serum or the synthetic serum replacement solution B27. Within 24 h of culture, elongated cells with long processes extended out from the explants of both tissues and were positively stained for various neuronal markers such as transitin, Tuj-1 and acetylated tubulin. After a longer culture period, cells positive for photoreceptor markers like rhodopsin, iodopsin and visinin were found, suggesting that the iris tissues contain retinal stem/progenitor-like cells. Several growth factors were examined to determine their effects on neuronal differentiation. EGF was shown to dramatically enhance neuronal cell differentiation, particularly the elongation of neuronal fibers. The addition of exogenous FGF2, however, did not show any positive effects on neuronal differentiation, although FGF signaling inhibitor, SU5402, suppressed neuronal differentiation. The results show that neuronal stem/progenitor-like cells can differentiate into neuronal cells immediately after they are transferred into an appropriate environment. This process did not require any exogenous factors, suggesting that neural stem/progenitor-like cells are simply suppressed from neuronal differentiation within the tissue, and isolation from the tissue releases the cells from the suppression mechanism.

Architecture of the subendothelial elastic fibers of small blood vessels and variations in vascular type and size.

Most blood vessels contain elastin that provides the vessels with the resilience and flexibility necessary to control hemodynamics. Pathophysiological hemodynamic changes affect the remodeling of elastic components, but little is known about their structural properties. The present study was designed to elucidate, in detail, the three-dimensional (3D) architecture of delicate elastic fibers in small vessels, and to reveal their architectural pattern in a rat model. The fine vascular elastic components were observed by a newly developed scanning electron microscopy technique using a formic acid digestion with vascular casts. This method successfully visualized the 3D architecture of elastic fibers in small blood vessels, even arterioles and venules. The subendothelial elastic fibers in such small vessels assemble into a sheet of meshwork running longitudinally, while larger vessels have a higher density of mesh and thicker mesh fibers. The quantitative analysis revealed that arterioles had a wider range of mesh density than venules; the ratio of density to vessel size was higher than that in venules. The new method was useful for evaluating the subendothelial elastic fibers of small vessels and for demonstrating differences in the architecture of different types of vessels.

Tsukushi functions as a Wnt signaling inhibitor by competing with Wnt2b for binding to transmembrane protein Frizzled4.

The Wnt signaling pathway is essential for the development of diverse tissues during embryogenesis. Signal transduction is activated by the binding of Wnt proteins to the type I receptor low-density lipoprotein receptor-related protein 5/6 and the seven-pass transmembrane protein Frizzled (Fzd), which contains a Wnt-binding site in the form of a cysteine-rich domain. Known extracellular antagonists of the Wnt signaling pathway can be subdivided into two broad classes depending on whether they bind primarily to Wnt or to low-density lipoprotein receptor-related protein 5/6. We show that the secreted protein Tsukushi (TSK) functions as a Wnt signaling inhibitor by binding directly to the cysteine-rich domain of Fzd4 with an affinity of 2.3 × 10(-10) M and competing with Wnt2b. In the developing chick eye, TSK is expressed in the ciliary/iris epithelium, whereas Wnt2b is expressed in the adjacent anterior rim of the optic vesicle, where it controls the differentiation of peripheral eye structures, such as the ciliary body and iris. TSK overexpression effectively antagonizes Wnt2b signaling in chicken embryonic retinal cells both in vivo and in vitro and represses Wnt-dependent specification of peripheral eye fates. Conversely, targeted inactivation of the TSK gene in mice causes expansion of the ciliary body and up-regulation of Wnt2b and Fzd4 expression in the developing peripheral eye. Thus, we uncover a crucial role for TSK as a Wnt signaling inhibitor that regulates peripheral eye formation.

Novel variants of Oct-3/4 gene expressed in mouse somatic cells.

It has been suggested that Oct-3/4 may regulate self-renewal in somatic stem cells, as it does in embryonic stem cells. However, recent reports raise the possibility that detection of human Oct-3/4 expression by RT-PCR is prone to artifacts generated by pseudogene transcripts and argue against a role for Oct-3/4 in somatic cells. In this study, we clarified Oct-3/4 expression in mouse somatic tissues using designed PCR primers, which can exclude amplification of its pseudogenes. We found that novel alternative transcripts are indeed expressed in somatic tissues, rather than the normal length transcripts in germline and ES cells. The alternative transcripts indicate the expression of two kinds of truncated proteins. Furthermore, we determined novel promoter regions that are sufficient for the expression of Oct-3/4 transcript variants in somatic cells. These findings provide new insights into the postnatal role of Oct-3/4 in somatic tissues.

Multipotent cells from mammalian iris pigment epithelium.

The regeneration of lens tissue from the iris of newts has become a classical model of developmental plasticity, although little is known about the corresponding plasticity of the mammalian iris. We here demonstrate and characterize multipotent cells within the iris pigment epithelium (IPE) of postnatal and adult rodents. Acutely-isolated IPE cells were morphologically homogeneous and highly pigmented, but some produced neurospheres which expressed markers characteristic of neural stem/progenitor cells. Stem/progenitor cell markers were also expressed in the IPE in vivo both neonatally and into adulthood. Inner and outer IPE layers differentially expressed Nestin (Nes) in a manner suggesting that they respectively shared origins with neural retina (NR) and pigmented epithelial (RPE) layers. Transgenic marking enabled the enrichment of Nes-expressing IPE cells ex vivo, revealing a pronounced capacity to form neurospheres and differentiate into photoreceptor cells. IPE cells that did not express Nes were less able to form neurospheres, but a subset initiated the expression of pan-neural markers in primary adherent culture. These data collectively suggest that discrete populations of highly-pigmented cells with heterogeneous developmental potencies exist postnatally within the IPE, and that some of them are able to differentiate into multiple neuronal cell types.

Developmental ability of cloned embryos from neural stem cells.

The success rate is generally higher when cloning mice from embryonic stem (ES) cell nuclei than from somatic cell nuclei, suggesting that the embryonic nature or the undifferentiated state of the donor cell increases cloning efficiency. We assessed the developmental ability of cloned embryos derived from cultured neural stem cell (NSC) nuclei and compared the success rate with that of embryos cloned from other donor cells such as differentiated NSCs, cumulus cells, Sertoli cells and ES cells in the mouse. The transfer of two-cell cloned embryos derived from cultured NSC nuclei into surrogate mothers produced five live cloned mice. However, the success rate (0.5%) was higher in embryos cloned from cultured NSC nuclei than from differentiated NSCs (0%), but lower than that obtained by cloning mice from other cell nuclei (2.2-3.5%). Although the in vitro developmental potential to the two-cell stage of the cloned embryos derived from NSC nuclei (73%) was similar to that of the cloned embryos derived from other somatic cell nuclei (e.g., 85% in Sertoli cells and 75% in cumulus cells), the developmental rate to the morula-blastocyst stage was only 7%. This rate is remarkably lower than that produced from other somatic cells (e.g., 50% in Sertoli cells and 54% in cumulus cells). These results indicate that the undifferentiated state of neural cells does not enhance the cloning efficiency in mice and that the arrest point for in vitro development of cloned embryos depends on the donor cell type.

Retinal stem/progenitor properties of iris pigment epithelial cells.

Neural stem cells/progenitors that give rise to neurons and glia have been identified in different regions of the brain, including the embryonic retina and ciliary epithelium of the adult eye. Here, we first demonstrate the characterization of neural stem/progenitors in postnatal iris pigment epithelial (IPE) cells. Pure isolated IPE cells could form spheres that contained cells expressing retinal progenitor markers in non-adherent culture. The spheres grew by cell proliferation, as indicated by bromodeoxyuridine incorporation. When attached to laminin, the spheres forming IPE derived cells were able to exhibit neural phenotypes, including retinal-specific neurons. When co-cultured with embryonic retinal cells, or grafted into embryonic retina in vivo, the IPE cells could also display the phenotypes of photoreceptor neurons and Muller glia. Our results suggest that the IPE derived cells have retinal stem/progenitor properties and neurogenic potential without gene transfer, thereby providing a novel potential source for both basic stem cell biology and therapeutic applications for retinal diseases.

Adult human retinal pigment epithelial cells capable of differentiating into neurons.

We investigated the ability of adult human RPE cells to differentiate into neurons. Two cell lines were evaluated. The cells were cultured in medium with 8% serum, transferred to a neural stem cell maintenance culture, and induced to differentiate with retinoic acid. The cells were immunocytochemically examined at each step. The cells showed epithelial-like morphology with 8% serum and all were immunoreactive for beta-III tubulin. After transfer to the stem cell maintenance culture, they changed morphologically and became immunoreactive for MAP5 and neurofilament200 after inducement with retinoic acid. The ratio of MAP5 positive cells was higher in the young adult RPE cell line. No GFAP or rod-opsin immunoreactive cells were observed. Adult human RPE cells even from old person are capable of differentiating into neurons, although the ratio of mature neurons was greater in the young than in the old cell line in this condition.

F9 Cells Can be Differentiated toward Two Distinct, Mutually Exclusive Pathways by Retinoic Acid and Sodium Butyrate: (teratocarcinoma/differentiation/retinoic acid/sodium butyrate).

Both retinoic acid (RA) and sodium butyrate (NaB) induce differentiation in embryonal carcinoma F9 cells. Phenotypic changes caused by RA are irreversible, whereas those of NaB are rapid and reversible. In this study, we investigated the effects of combinations of these two agents on F9 cell differentiation and showed that RA had no effect on the cells induced to differentiate with NaB and vice versa. Thus, F9 cells are induced to differentiate along two distinct pathways which are mutually exclusive.