Epithelial Differentiation Markers Research Articles

Perlecan-Deficient Mutation Impairs Corneal Epithelial Structure

To elucidate the role of perlecan (Hspg2), a large multidomain heparan sulfate proteoglycan expressed in the basement membrane, in the structure of the corneal epithelium. A previously developed perlecan-deficient (Hspg2⁻/⁻-Tg) mouse model was used. Histologic analysis of their corneas was performed by light and transmission electron microscopy. The localization of perlecan in the corneas of wild-type (WT) mice and Hspg2⁻/⁻-Tg mice was examined by immunohistochemistry. The effects of perlecan deficiency on corneal epithelial structure was analyzed with respect to the expression of corneal epithelial proliferation and differentiation markers, such as Ki67, cytokeratin12 (K12), connexin43 (Cx43), Notch1, and Pax6 by immunohistochemistry and real-time polymerase chain reaction (PCR). The Hspg2⁻/⁻-Tg mice had microphthalmos and a thinner corneal epithelium compared with that of the WT mice. Perlecan was localized in the corneal epithelial basement membrane in the WT mice, but not in the Hspg2⁻/⁻-Tg mice. The Hspg2⁻/⁻-Tg corneal epithelium exhibited thinner wing cell layers and a decreased number of Ki67-positive cells, but no dead cells, compared with the WT corneal epithelium. Immunohistochemistry and real-time PCR analysis revealed a significantly decreased expression of corneal epithelial differentiation markers such as K12, Cx43, Notch1, and Pax6 in Hspg2⁻/⁻-Tg mice, compared with those of the WT mice. The findings of this study highlight a strong correlation between the presence of perlecan in the basement membrane and the structure of corneal epithelium and that the perlecan-deficient mutation impairs corneal epithelial structure.

Expression of Pluripotency and Multipotency Factors in Human Ocular Surface Tissues

Aim: Mechanisms that control ocular surface stem cells (SCs) are unclear. Recent studies have shown that several adult SCs express pluripotency markers. Our objective was to analyze the expression of key molecules of pluripotency in human ocular surface tissues as well as in cultivated limbal epithelium.Methods: Four samples of human corneal, limbal and on amniotic membrane cultivated limbal epithelium (HLEC-AM), as well as bulbar and fornical conjunctiva were analyzed. Human embryonic stem (ES) cells and human umbilical vein endothelial cells served as controls. Expression of corneal epithelial differentiation markers (K3, K12, Cx43), putative limbal SC markers (ABCG2, p63, K15), and molecules associated with pluripotency/multipotency (NANOG, OCT4, SOX2, KLF4, KIT, NESTIN, PAX6, NOTCH1) was examined using real-time polymerase chain reaction (PCR) and immunohistochemical staining.Results: Limbal epithelium showed a significantly (p < 0.05) higher expression of K15, ABCG2, OCT4, SOX2, NESTIN and NOTCH1, but a lower expression of K3 than corneal epithelium. Besides a higher expression of ABCG2 in fornix, the expression of pluripotency markers was similar in both conjunctival regions, although lower than in limbal epithelium. Expression of pluripotency factors in ES cells was significantly higher than in ocular surface SCs, whereas the expression in limbal epithelium was the closest to ES cells. HLEC-AM in comparison to limbal epithelium showed a lower expression of differentiation markers, a similar expression of ABCG2 but a significantly lower expression of pluripotency factors.Conclusion: Human ocular surface epithelial cells and especially limbal epithelial cell express genes are important for pluripotency and may have preserved some common mechanisms with pluripotent SCs.

Protective Effects of Prepubertal Genistein Exposure on Mammary Tumorigenesis Are Dependent on BRCA1 Expression

This study investigated whether prepubertal dietary exposure to genistein reduces mammary tumorigenesis by upregulating Brca1 expression in mice. Heterozygous Brca1(+/-) mice and their wild-type (WT) littermates were fed control AIN93G diet or 500 ppm genistein-supplemented AIN93G diet from postnatal day (PND) 15 to PND30 and then switched to AIN93G diet. Prepubertal dietary exposure to genistein reduced 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary incidence (P = 0.029) and aggressiveness of the tumors (P < 0.001) in the WT mice and upregulated the expression of Brca1 in their mammary glands (P = 0.04). In contrast, prepubertal genistein diet neither significantly reduced mammary tumorigenesis or tumor aggressivity nor increased Brca1 mRNA expression in the Brca1(+/-) mice. These results may be related to the opposing effects of prepubertal genistein diet on the expression of Rankl and CK5/CK18 ratio (marker of luminal epithelial cell differentiation) in the mammary gland and estrogen receptor (ER-α) and progesterone receptor (PgR) protein levels in the mammary tumor: these all were reduced in the WT mice or increased in Brca1(+/-) mice. Both the WT and Brca1(+/-) mice exhibited reduced levels of amphiregulin, CK5, and CK18, delayed ductal elongation and a reduction in terminal end bud number in the normal mammary gland, and reduced HER-2 protein levels in the mammary tumors; however, these effects were not sufficient to significantly reduce mammary tumorigenesis in Brca1(+/-) mice. Our results show that upregulation of Brca1 may be required for prepubertal dietary genistein exposure to reduce later mammary tumorigenesis, perhaps because in the absence of this upregulation, mice do not exhibit genistein-induced downregulation of ER-α, PgR, and Rankl.

Overexpression of 14-3-3σ counteracts tumorigenicity by positively regulating p73 in vivo

14-3-3σ, one of the 14-3-3 family members, was initially identified as a human mammary epithelium-specific marker 1. The expression of 14-3-3σ is directly regulated by p53. It has been demonstrated that 14-3-3σ stabilizes p53 and enhances its transcriptional activity through the interaction with p53, suggesting that 14-3-3σ has a positive feedback effect on p53. Our previous study showed that 14-3-3σ is a direct transcriptional target of p73 and enhances the p73-mediated transcriptional as well as pro-apoptotic activity in vitro. In the present study, we explored the tumor-suppressive effect of 14-3-3σ by establishing a breast cancer xenograft nude mouse model with an inducible expression of 14-3-3σ or with an inducible expression of p53/p73 plus 14-3-3σ with ADR treatment. Tumor formation was then assayed. Moreover, 66 primary breast cancer specimens and paired tumor-free breast specimens obtained from the female patients were examined. Results showed that the expression of p73 and 14-3-3σ in breast cancer specimens was significantly lower than the tumor-free breast specimens and that 14-3-3σ expression was positively correlated with the expression of p73. Furthermore, overexpression of 14-3-3σ counteracts tumorigenicity by positively regulating p73 in p53-mutated or -deficient cancers in vivo. Therefore, our results may lead to the use of 14-3-3σ in the therapeutic application for the p53-mutated and p73-expressed breast cancer patients.

Dickkopf-3 maintains the PANC-1 human pancreatic tumor cells in a dedifferentiated state

Pancreatic cancer (PaCa) is the fourth leading cause of cancer deaths in Western societies, with pancreatic ductal adenocarcinomas (PDACs) accounting for >90% of such cases. PDAC is a heterogeneous disease that includes a subset showing overexpression of the secreted glycoprotein Dickkopf-related protein 3 (Dkk-3), a protein shown to be downregulated in various cancers of different tissues. The biological function of Dkk-3 in this subset was studied using the Dkk-3 expressing PANC-1 cell line as a model for PDACs. The influence of Dkk-3 overexpression and knockdown on cellular differentiation and proliferation of PANC-1 was investigated. Confocal microscopy showed that Dkk-3 was expressed in a fraction of PANC-1 cells. While lentiviral-mediated overexpression of DKK3 did not alter cellular proliferation, knockdown of DKK3 resulted in significant reduction of cellular proliferation and concomitant induction of cell cycle inhibitors CDKN2B (p15INK4b), CDKN1A (p21CIP1) and CDKN1B (p27KIP1). In parallel, pancreatic epithelial cell differentiation markers AMY2A, CELA1, CTRB1, GCG, GLB1 and INS were significantly upregulated. PANC-1 cells differentiated using exendin-4 showed analogous induction of cell cycle inhibitors and differentiation markers. Thus, we conclude that Dkk-3 is required to maintain a highly dedifferentiated and consequently proliferative state in PANC-1, indicating a similar function in the Dkk-3 overexpressing subset of PDACs. Therefore, Dkk-3 represents a potential target for the treatment of Dkk-3-positive subtypes of PaCa to drive cells into cell cycle arrest and differentiation.

Morphological evaluation of tongue mucosa in burning mouth syndrome

ObjectiveThe aim of the present study was to perform a morphological evaluation by immunofluorescence of biomarkers of keratinocyte intercellular adhesion, and of differentiation in the tongue mucosa of burning mouth syndrome patients (BMS), compared with a control group. DesignA prospective blinded evaluation of tongue mucosal specimens processed for light microscopy was performed. Intercellular adhesion was evaluated by investigating the expression of desmoglein 1, desmoglein 3, and of occludin. Keratin 10 and keratin 14 (markers of epithelial differentiation) were also evaluated, as keratin 16 (marker for activated keratinocytes after epithelial injury). Apoptotic cascade was investigated by p53 and activated caspase-3 expression. The basal membrane integrity was analysed through laminin immunoreactivity. ResultsIn both groups, a preserved three-dimensional architecture of the tongue was observed. Desmoglein 1 and desmoglein 3 epithelial distributions were similar in the desmosomes of patients and control subjects. Again, keratin 10 immunoreactivity and distribution pattern of keratin 14 in the epithelial compartment was similar in both groups. In control samples, keratin 16 immunoreactivity was scant throughout the epithelium with a punctuate and scattered cytoplasmic labelling. In contrast, in all BMS patients keratinocyte cytoplasm was homogeneously labelled for keratin 16, with a more intense staining than controls. Furthermore, keratin 16 staining progressively decreased proceeding towards the most superficial epithelial layers. ConclusionsThe results of this study are consistent with and support the clinically normal features of oral mucosa in BMS, and suggest that keratin 16 may be involved in the cell mechanisms underlying the syndrome occurrence.

Low doses ionizing radiation enhances the invasiveness of breast cancer cells by inducing epithelial–mesenchymal transition

Epithelial–mesenchymal transition (EMT) is a process cellular morphologic and molecular alterations facilitate cell invasion. We hypothesized that low dose ionizing irradiation (LDIR) enhances the invasiveness of breast cancer cells by inducing EMT. The effects of LDIR on cellular morphology and the EMT markers of MCF-7 breast cancer cells were analyzed by western blot/RT-PCR and migration/invasion was examined using the transwell assay. We found that LDIR led to the phenotypic changes of EMT in MCF-7 cells and down-regulation of epithelial differentiation markers and transcriptional induction of mesenchymal markers. Furthermore, the radiated cells demonstrated enhanced migration/invasion MCF-7 cells compared with non-radiated cells. In summary, LDIR promotes the invasiveness of breast cancer cells through epithelial to mesenchymal transition. These findings may ultimately provide a new targeted approach for improving the therapeutic effectiveness of radiation in breast cancer.

Estrogen receptor silencing induces epithelial to mesenchymal transition in human breast cancer cells.

We propose the hypothesis that loss of estrogen receptor function which leads to endocrine resistance in breast cancer, also results in trans-differentiation from an epithelial to a mesenchymal phenotype that is responsible for increased aggressiveness and metastatic propensity. siRNA mediated silencing of the estrogen receptor in MCF7 breast cancer cells resulted in estrogen/tamoxifen resistant cells (pII) with altered morphology, increased motility with rearrangement and switch from a keratin/actin to a vimentin based cytoskeleton, and ability to invade simulated components of the extracellular matrix. Phenotypic profiling using an Affymetrix Human Genome U133 plus 2.0 GeneChip indicated geometric fold changes ≥3 in approximately 2500 identifiable unique sequences, with about 1270 of these being up-regulated in pII cells. Changes were associated with genes whose products are involved in cell motility, loss of cellular adhesion and interaction with the extracellular matrix. Selective analysis of the data also showed a shift from luminal to basal cell markers and increased expression of a wide spectrum of genes normally associated with mesenchymal characteristics, with consequent loss of epithelial specific markers. Over-expression of several peptide growth factors and their receptors are indicative of an increased contribution to the higher proliferative rates of pII cells as well as aiding their potential for metastatic activity. Signalling molecules that have been identified as key transcriptional drivers of epithelial to mesenchymal transition were also found to be elevated in pII cells. These data support our hypothesis that induced loss of estrogen receptor in previously estrogen/antiestrogen sensitive cells is a trigger for the concomitant loss of endocrine dependence and onset of a series of possibly parallel events that changes the cell from an epithelial to a mesenchymal type. Inhibition of this transition through targeting of specific mediators may offer a useful supplementary strategy to circumvent the effects of loss of endocrine sensitivity.

Occasional Staining for p63 in Malignant Vascular Tumors: A Potential Diagnostic Pitfall

Expression of p63, a putative marker for epithelial or myoepithelial differentiation, has been used to distinguish spindle cell carcinoma from sarcoma. The specificity of p63 for epithelial differentiation has not been thoroughly evaluated however, since p63 expression has been explored in only a handful of mesenchymal tumors. After observing unexpected immunohistochemical staining for p63 in an angiosarcoma of the breast, we evaluated a series of benign and malignant vascular tumors to determine the frequency of such a finding. Nuclear immunoreactivity to p63 was detected, at least focally, in 24% of malignant vascular tumors other than Kaposi sarcoma, which was uniformly negative. Benign vascular tumors were also negative for p63. Although p63 expression in tumors of vascular differentiation is unusual, it may be seen occasionally in some malignant vascular tumors. Thus, p63 is not entirely specific for epithelial differentiation. Since soft tissue angiosarcomas and hemangioendotheliomas sometimes express cytokeratins, the finding of nuclear p63 represents another potential pitfall in the differential diagnosis between poorly-differentiated carcinomas and vascular neoplasms.

Nucleostemin affects the proliferation but not differentiation of oral squamous cell carcinoma cells

Nucleostemin (NS) has been reported as essential for stem and cancer cell proliferation. To investigate the significance of NS in oral squamous cell carcinomas (OSCCs), we examined NS expression in neoplastic tissue of the tongue and in OSCC cell lines. Nucleostemin expression in the histological samples showed positive correlation with Ki-67 expression. Furthermore, NS expression was associated with cellular proliferation in OSCC cell lines using siRNA, which upregulated p27, a cyclin-dependent kinase inhibitor. Regarding OSCC differentiation, NS expression did not influence cornification or oral epithelial differentiation markers such as involucrin and cytokeratin19. Thus, NS is widely expressed in normal and neoplastic oral epithelial tissues, and is likely a marker of proliferation.

Abstract 4176: The biology of circulating nucleic acid in non-small cell lung cancer and prognostic implication

Abstract Background: Increased amount of circulating nucleic acid in plasma or serum (CNAPS) of cancer patient had been confirmed in many studies. The source of CNAPS was still enigmatic however the correlation with prognostic outcome was confirmed in various types of cancer. These might be the effect of tumor-derived CNAPS, correlated with tumor burden; however the interaction of cancer and immune cell was not negligent. Material and Method: Fifty-eight plasma of advanced non-small cell lung cancer (NSCLC) and 52 sex/age match healthy volunteer were studied. Total amount of CNAPS was measured. We further explored substantial biology proportion of CNAPS according to cell source by using epithelial-specific marker, methylated SHP-1 promoter 2 (mSHP1P2), and hematopoietic-specific marker, unmethylated SHP-1 promoter 2 (uSHP1P2). Clinicopathological parameters were included with these markers evaluation. Result: Significantly increased amount of CNAPS in plasma of NSCLC compared with healthy volunteer. Median levels were 7.6 ngml-1 (range 1.3-49.8) and 4.6 ngml-1 (range 0.03-26.9) respectively (p = 0.002). The mSHP1P2 represented the increasing amount of tumor-derived CNAPS in NSCLC (p &amp;lt; 0.001). Contrast to uSHP1P2 which was the predominant portion of CNAPS in healthy volunteer. The mSHP1P2 level was correlated with prognostic strategy in NSCLC. Moreover proportion of uSHP1P2 level was also increased among NSCLC and it was related with survival outcome. Comparison CNAPS, mSHP1P2 and uSHP1P2 with baseline demographic parameters by multivariate analysis, total amount of CNAPS was the only independent parameter for prognostic assessment. The level of &amp;gt; 4.5 ngml-1 indicated shorter median PFS (2.6 months) and OS (4.7 months) while the level of &amp;lt; 4.5 ngml-1 indicated longer median PFS (5.6 months) and OS (&amp;gt;15 months) (p &amp;lt; 0.001). Conclusion: Total amount of CNAPS in NSCLC was the valuable prognostic implication confirmed by our study, the impact of both tumor and immune cell-derived portion. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4176. doi:10.1158/1538-7445.AM2011-4176

Thirdhand smoke: a new dimension to the effects of cigarette smoke on the developing lung

The underlying mechanisms and effector molecules involved in mediating in utero smoke exposure-induced effects on the developing lung are only beginning to be understood. However, the effects of a newly discovered category of smoke, i.e., thirdhand smoke (THS), on the developing lung are completely unknown. We hypothesized that, in addition to nicotine, other components of THS would also affect lung development adversely. Fetal rat lung explants were exposed to nicotine, 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA), or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the two main tobacco-specific N-nitrosamine constituents of THS, for 24 h. We then determined key markers for alveolar paracrine signaling [epithelial differentiation markers surfactant phospholipid and protein synthesis; mesenchymal differentiation markers peroxisome proliferator-activated receptor γ (PPAR-γ), fibronectin and calponin], the BCL-2-to-Bax ratio (BCL-2/Bax), a marker of apoptosis and the involvement of nicotinic acetylcholine receptors (nAChR)-α3 and -α7 in mediating NNA's and NNK's effects on the developing lung. Similar to the effects of nicotine, exposure of the developing lung to either NNK or NNA resulted in disrupted homeostatic signaling, indicated by the downregulation of PPAR-γ, upregulation of fibronectin and calponin protein levels, decreased BCL-2/Bax, and the accompanying compensatory stimulation of surfactant phospholipid and protein synthesis. Furthermore, nAChR-α3 and -α7 had differential complex roles in mediating these effects. NNK and NNA exposure resulted in breakdown of alveolar epithelial-mesenchymal cross-talk, reflecting lipofibroblast-to-myofibroblast transdifferentiation, suggesting THS constituents as possible novel contributors to in utero smoke exposure-induced pulmonary damage. These data are particularly relevant for designing specific therapeutic strategies, and for formulating public health policies to minimize THS exposure.

Endocervical Fibroblastic Malignant Peripheral Nerve Sheath Tumor (Neurofibrosarcoma)

Primary cervical stromal sarcomas are rare neoplasms that have been poorly characterized. We report the clinical, histologic, and immunohistologic features of 3 primary endocervical S100 protein (S100p)-positive and CD34-positive sarcomas, herein designated as fibroblastic malignant peripheral nerve sheath sarcoma (endocervical neurofibrosarcoma), 2 of which occurred in women younger than 35 years of age. All tumors presented as a cervical polyp or mass lesion; 1 extended into the pelvic side wall and vaginal soft tissue. The tumors measured 2.0 to 8.0 cm, and were composed of compact fascicles of spindled cells arranged in herringbone, loose fascicular, or ill-defined storiform patterns. A focal whorled architecture was identified in all 3 tumors, but distinct Antoni A areas and Verocay bodies were absent. Ultrastructural examination in 1 case confirmed the presence of fibrocyte-like differentiation. Strong, diffuse, and in 1 case, patchy S100p expression was seen in all cases; strong and diffuse CD34 expression was also present in all tumors. Adjacent uninvolved endocervical stroma also showed CD34 positivity but expression was much less dramatic than in tumor cells. All other markers of neural, melanocytic, smooth muscle, endometrial stromal, and epithelial differentiation were negative. One of the tumors behaved extremely aggressively with extensive pelvic involvement, resulting in patient death within 16 months of diagnosis; another tumor was associated with pelvic recurrence 13 months after diagnosis; and the third tumor had an indolent course with no evidence of recurrence at 33 months after complete excision and local radiotherapy, although follow-up was limited. Review of large numbers of mesenchymal tumors in the uterus did not show similar tumors. Endocervical neurofibrosarcoma should be distinguished from solitary fibrous tumor, endometrial stromal sarcoma, leiomyosarcoma, melanoma, and other spindle cell neoplasms. The prominent fibroblastic endoneurial-like differentiation seen in this peripheral nerve sheath tumor may be related to the presence of a rich mucosal stromal fibrocyte network in the endocervix.

Expression of keratins in cutaneous epithelial tumors and related disorders - distribution and clinical significance

Keratins are a highly diverse family of cytoskeletal proteins and important markers of epithelial cell differentiation. In this review, applying the new keratin nomenclature recently introduced, we summarize and discuss the distribution and significance of keratin patterns in cutaneous epithelial tumors in relation to the epithelial structures of normal human skin. The available literature data show that the analysis of keratin profiles broadens our understanding of the differentiation, nature and histogenetic origin of the various, highly singular epithelial tumors arising in the skin. Moreover, keratins may aid in histological diagnosis and, in certain instances, may be helpful for the recognition of tumor malignancy and aggressiveness. Furthermore, we briefly address the topic of keratin-related skin disorders.

Identifying Peptide Spectra In Wilms' Tumor That Associate With Adverse Events

Introduction: MALDI-TOF-IMS (matrix assisted laser desorption ionization time of flight imaging mass spectrometry) is a recently validated method for proteomic analysis of formalin-fixed, paraffin-embedded (FFPE) archived tissue specimens. We hypothesized that high-throughput proteomic analysis of Wilms' Tumor (WT) would yield biomarkers predictive of advanced disease stage and disease relapse. Methods: Two tissue microarrays (TMA) were assembled that contain 156 punches from FFPE WT tissue blocks stored in our embryonal tumor tissue repository. Multiple histologically selected tissue punches were taken from each block and included 30 WT, one renal rhabdomyosarcoma, five different gestational age human fetal kidneys, one hepatic, one pulmonary, and one nodal WT metastases. Coordinates of specimens within the TMA were uploaded to an acoustic robotic microspotter for deposition of trypsin and matrix formation. MALDI-TOF-IMS was performed, segregating peptide spectra based on differential mass-to-charge (m/z) ratios. Post-acquisition processing of this information enabled display of these m/z peaks as an ion-density map, where the relative abundance of the selected ion across the tissue is displayed on a color-intensity scale at each coordinate location, or pixel. Peptide spectra were compared across the two TMAs with respect to histology, similarity to expression patterns in fetal kidneys, stage of disease, disease relapse, and vital status. Results: Unique peptide spectral patterns were identified that corresponded with metastasis, treatment effect, and tumor necrosis. For example, increased expression of peptides with m/z of 1515.6, 1790.6, and 2215.5 corresponded with tumor-specific histologic regions of four separate pulmonary metastases in the same patient. In contrast, within these same pulmonary metastases, and in an additional pulmonary metastasis from a different patient, peptides with m/z of 1032.8, 1326.1, and 2190.0 showed decreased expression relative to other samples on the TMA. High peptide expression at m/z of 1529.3 and 1274.8 correlated with tumor necrosis and histologic post-treatment effect. Conclusions: MALDI-TOF-IMS has the ability to reveal unique peptide spectral patterns that associate with adverse events occurring in WT. More samples are necessary to draw such conclusions from the current study. Sequencing of these individual peptides will enable the search for biomarkers of disease that can clarify our understanding of WT pathogenesis, disease relapse, and adverse events. Identifying protein markers of epithelial and stromal differentiation may give insight into tumor differentiation.

From Hair to Cornea: Toward the Therapeutic Use of Hair Follicle-Derived Stem Cells in the Treatment of Limbal Stem Cell Deficiency

Limbal stem cell deficiency (LSCD) leads to severe ocular surface abnormalities that can result in the loss of vision. The most successful therapy currently being used is transplantation of limbal epithelial cell sheets cultivated from a limbal biopsy obtained from the patient's healthy, contralateral eye or cadaveric tissue. In this study, we investigated the therapeutic potential of murine vibrissae hair follicle bulge-derived stem cells (HFSCs) as an autologous stem cell (SC) source for ocular surface reconstruction in patients bilaterally affected by LSCD. This study is an expansion of our previously published work showing transdifferentiation of HFSCs into cells of a corneal epithelial phenotype in an in vitro system. In this study, we used a transgenic mouse model, K12(rtTA/rtTA) /tetO-cre/ROSA(mTmG) , which allows for HFSCs to change color, from red to green, once differentiation to corneal epithelial cells occurs and Krt12, the corneal epithelial-specific differentiation marker, is expressed. HFSCs were isolated from transgenic mice, amplified by clonal expansion on a 3T3 feeder layer, and transplanted on a fibrin carrier to the eye of LSCD wild-type mice (n = 31). The HFSC transplant was able to reconstruct the ocular surface in 80% of the transplanted animals; differentiating into cells with a corneal epithelial phenotype, expressing Krt12, and repopulating the corneal SC pool while suppressing vascularization and conjunctival ingrowth. These data highlight the therapeutic properties of using HFSC to treat LSCD in a mouse model while demonstrating a strong translational potential and points to the niche as a key factor for determining stem cell differentiation.

A role for Notch signaling in corneal wound healing

To identify the role of the Notch signaling pathway in corneal wound healing, rat corneas receiving either epithelial or stromal wounds were placed in organ culture for up to 3 and 14 days, respectively. Localization of Notch receptors--Notch1, Notch2, and their ligands--Delta1, Jagged1 was determined by immunofluorescence. Wounds were treated with a γ-secretase inhibitor to suppress Notch signaling or recombinant Jagged1 to enhance Notch signaling and morphological changes in the epithelium and stroma were recorded. The expressions of markers of cell proliferation (Ki67) and epithelial differentiation (cytokeratin 3) were assessed by immunohistology. Notch1 and Notch2 were localized to suprabasal epithelial cells in normal corneas. During corneal wound healing, both Notch receptors were detected in suprabasal and superficial epithelial layers. Delta1 and Jagged1 were observed throughout all corneal epithelial cell layers and occasional keratocytes of the stroma in normal and wounded corneas. γ-secretase inhibition of Notch resulted in increased epithelial cell layers, with recombinant Jagged1 activation of Notch leading to a reduction in epithelial cell layers during corneal wound healing. Correspondingly, the activation of Notch resulted in a decreased cytokeratin 3 expression in the corneal epithelium, with no effect on cellular expression of Ki67. Notch signaling pathway suppressed corneal epithelial differentiation during corneal wound healing, but had no effect on epithelial cell proliferation.

The generation of 3-D tissue models based on hyaluronan hydrogel-coated microcarriers within a rotating wall vessel bioreactor

With the increasing necessity for functional tissue- and organ equivalents in the clinic, the optimization of techniques for the in vitro generation of organotypic structures that closely resemble the native tissue is of paramount importance. The engineering of a variety of highly differentiated tissues has been achieved using the rotating wall vessel (RWV) bioreactor technology, which is an optimized suspension culture allowing cells to grow in three-dimensions (3-D). However, certain cell types require the use of scaffolds, such as collagen-coated microcarrier beads, for optimal growth and differentiation in the RWV. Removal of the 3-D structures from the microcarriers involves enzymatic treatment, which disrupts the delicate 3-D architecture and makes it inapplicable for potential implantation. Therefore, we designed a microcarrier bead coated with a synthetic extracellular matrix (ECM) composed of a disulfide-crosslinked hyaluronan and gelatin hydrogel for 3-D tissue engineering, that allows for enzyme-free cell detachment under mild reductive conditions (i.e. by a thiol-disulfide exchange reaction). The ECM-coated beads (ECB) served as scaffold to culture human intestinal epithelial cells (Int-407) in the RWV, which formed viable multi-layered cell aggregates and expressed epithelial differentiation markers. The cell aggregates remained viable following dissociation from the microcarriers, and could be returned to the RWV bioreactor for further culturing into bead-free tissue assemblies. The developed ECBs thus offer the potential to generate scaffold-free 3-D tissue assemblies, which could further be explored for tissue replacement and remodeling.

Overexpression of YAP1 induces immortalization of normal human keratinocytes by blocking clonal evolution

YAP1 is a transcriptional co-activator able to bind several transcription factors. YAP1 was termed a candidate oncogene after it was shown to be in human chromosome 11q22 amplicon; besides the genomic amplification, several experiments indicated that it has oncogenic function. However, YAP1 was also reported to be a tumor suppressor as its gene locus is deleted in some breast cancers. To clarify the role of this protein in the physiology of rapidly renewal cells, we investigated YAP1 in human keratinocytes. Here, we show that YAP1 overexpression in primary human keratinocytes blocks clonal evolution and induces cell immortalization, but not malignant transformation. YAP1 overexpression led to an increase in cell proliferation, colony forming efficiency and holoclone percentage. Cells escaped from senescence, immortalized but still remained unable to grow in soft agar or express mesenchymal markers, suggesting that YAP1 overexpression is not sufficient to promote a complete epithelial-mesenchymal transition and tumorigenic transformation. Protein analysis showed an increase in epithelial proliferation markers and a decrease in epithelial differentiation markers. The expression of LEKTI, a late differentiation marker, dramatically dropped to undetectable levels. Taken together, these data suggest that YAP1-overexpressing keratinocytes are maintained in the proliferative compartment.

Prognostic Significance of Melanoma Differentiation and Trans-Differentiation

Cutaneous malignant melanomas share a number of molecular attributes such as limitless replicative potential that define capabilities acquired by most malignancies. Accordingly, much effort has been focused on evaluating and validating protein markers related to these capabilities to function as melanoma prognostic markers. However, a few studies have also highlighted the prognostic value of markers that define melanocytic differentiation and the plasticity of melanoma cells to trans-differentiate along several other cellular pathways. Here, we provide a comprehensive review and evaluation of the prognostic significance of melanocyte-lineage markers such as MITF and melanogenic proteins, as well as markers of vascular epithelial and neuronal differentiation.