Acceleration of the formation of cultured epithelium using the sonic hedgehog expressing feeder cells

Ar-Turmerone Exerts Anti-proliferative and Anti-inflammatory Activities in HaCaT Keratinocytes by Inactivating Hedgehog Pathway

Psoriasis, a common skin inflammatory disorder, is characterized by the aberrant growth and differentiation of keratinocytes. Ar-Turmerone, a main bioactive ingredient of Curcuma longa, has been found to alleviate skin inflammation in psoriasis-like mice. However, the effects and underlying mechanism of ar-turmerone on keratinocytes remain unknown. The effects of ar-turmerone alone or combined with recombinant human sonic hedgehog (rhShh) on cell proliferation, apoptosis, and inflammatory cytokine secretion were explored by MTT, flow cytometry analysis, and ELISA, respectively. The mRNA and protein levels of Shh, glioblastoma-1 (Gli1), and smoothened (SMO) were determined by RT-qPCR and western blot analysis, respectively. Results disclosed that ar-turmerone dose-dependently suppressed proliferation, facilitated apoptosis, and reduced TNF-α-mediated production of interleukin (IL)-1β, IL-6, and IL-8 in HaCaT cells. Ar-turmerone blocked Hedgehog pathway in HaCaT cells, as evidenced by the reduced expression of Shh, Gli1, and SMO. Moreover, activation of the Hedgehog pathway by rhShh abolished the effects of ar-turmerone on the proliferation, apoptosis, and TNF-α-mediated inflammatory cytokine expression in HaCaT cells. In conclusion, ar-turmerone suppressed cell proliferative ability and attenuated inflammatory cytokine expression by inactivating Hedgehog pathway in HaCaT cells, contributing to better understanding the potential anti-psoriasis effects of ar-turmerone on psoriasis.

Effects of recombinant human parathyroid hormone (1-34)on cell proliferation, chemokine expression and the Hedgehog pathway in keratinocytes

Psoriasis is an autoimmune disease involving the excessive proliferation of keratinocytes mediated by T‑cells. Parathyroid hormone (PTH) has been identified as an essential factor in the treatment of psoriasis. In the present study, the mechanism underlying the effect of recombinant human parathyroid hormone (rhPTH) (1‑34) in keratinocytes was investigated. The effects of rhPTH (1‑34) on cell proliferation, cell cycle, and the secretion and expression of C‑X‑C motif chemokine 11 (CXCL11) and components of the Hedgehog signaling pathway were examined in HaCaT cells by MTT assay, flow cytometric analysis, ELISA and gene chip analysis. The data showed that rhPTH (1‑34) significantly inhibited keratinocyte proliferation at concentrations >8x10‑7 mol/l. rhPTH (1‑34) induced G1 phase arrest of the cell cycle in the keratinocytes. The secretion of CXCL11 in tumor necrosis factor (TNF)‑α‑induced keratinocytes was downregulated by rhPTH (1‑34) in a dose‑dependent manner, compared with that in keratinocytes treated with TNF‑α alone. It was also found that rhPTH (1‑34) inhibited the expression of CXCL11 in the HaCaT cells. rhPTH (1‑34) also affected the Hedgehog signaling pathway specifically by regulating the expression of associated genes. In conclusion, these data suggested that rhPTH (1‑34) inhibited cell proliferation, and the secretion and expression of CXCL11 in HaCaTs. rhPTH (1‑34) also altered the expression of associated genes in the Hedgehog pathway. Therefore, rhPTH (1‑34) can be considered as a novel therapeutic agent for the treatment of psoriasis.

Engineering epithelial-stromal interactions in vitro for toxicology assessment

Crosstalk between epithelial and stromal cells drives the morphogenesis of ectodermal organs during development and promotes normal mature adult epithelial tissue homeostasis. Epithelial-stromal interactions (ESIs) have historically been examined using mammalian models and ex vivo tissue recombination. Although these approaches have elucidated signaling mechanisms underlying embryonic morphogenesis processes and adult mammalian epithelial tissue function, they are limited by the availability of tissue, low throughput, and human developmental or physiological relevance. In this review, we describe how bioengineered ESIs, using either human stem cells or co-cultures of human primary epithelial and stromal cells, have enabled the development of human in vitro epithelial tissue models that recapitulate the architecture, phenotype, and function of adult human epithelial tissues. We discuss how the strategies used to engineer mature epithelial tissue models in vitro could be extrapolated to instruct the design of organotypic culture models that can recapitulate the structure of embryonic ectodermal tissues and enable the in vitro assessment of events critical to organ/tissue morphogenesis. Given the importance of ESIs towards normal epithelial tissue development and function, such models present a unique opportunity for toxicological screening assays to incorporate ESIs to assess the impact of chemicals on mature and developing epidermal tissues.

Aberrant expression of Sonic hedgehog signaling in Peutz-Jeghers syndrome

The SHH signaling pathway is critical for gastrointestinal development and organic patterning, and dysregulation of SHH pathway molecules has been detected in multiple gastrointestinal neoplasms. This study investigated the role of the SHH signaling pathway in PJS. Expression of SHH, PTCH, and GLI1 was examined by real-time PCR and immunohistochemistry in 20 normal tissues and 75 colorectal lesions (25 PJPs, 25 adenomas, and 25 adenocarcinomas). Expression of SHH, PTCH, and GLI1 mRNA was higher in PJPs than in normal tissue (P < .05) and gradually increased along the PJP-adenoma-adenocarcinoma sequence (P < .05). Immunostaining indicated that SHH expression was present in 60% of PJPs, 72% of adenomas, and 84% of carcinomas, whereas 68% of PJPs, 72% of adenomas, and 88% of carcinomas exhibited cytoplasmic expression of PTCH. Moreover, high GLI1 expression was detected in 56% of PJPs, 64% of adenomas, and 80% of carcinomas; and high nuclear expression of GLI1 was observed in 8 adenomas with atypia and 15 carcinomas. Increased SHH, PTCH, and GLI1 protein correlated positively with tumor grade (P = .012, P = .003, and P = .007, respectively), tumor depth (P = .024, P = .007, and P = .01), and lymph node metastasis (P = .05, P = .015, and P = .005). This study identified aberrant expression of SHH pathway molecules in PJS, and the findings may supply a novel mechanism for the development of PJ polyps.

Human adipose tissue-derived mesenchymal stem cells as a novel feeder layer for epithelial cells

We examined a novel human feeder cell layer of mesenchymal stem cells harvested from human adipose tissues. Gene expression analyses and colony-forming assay with human primary epithelial cells showed that the adipose tissue-derived mesenchymal stem cells produced various factors to support epithelial stem/progenitor maintenance and cell growth. Using the mesenchymal stem cells as novel feeder layers, transplantable epithelial cell sheets could be effectively generated ex vivo on temperature-responsive cell-culture surfaces.

Role of sonic hedgehog in maintaining a pool of proliferating stem cells in the human fetal epidermis

BACKGROUND

The mammalian epidermis is maintained by the ongoing proliferation of a subpopulation of keratinocytes known as epidermal stem cells. Sonic hedgehog (Shh) can regulate morphogenesis of hair follicles and several types of skin cancer, but the effect of Shh on proliferation of human putative epidermal stem cells (HPESCs) is poorly understood.

METHODS AND RESULTS

We first found that Shh, its receptors Patched1 (Ptc1) as well as Smoothened (Smo) and its downstream transcription factor Gli-1 were expressed in the basal layer of human fetal epidermis and freshly sorted HPESCs. Next, treatment of HPESCs with media conditioned by Shh-N-expressing cells promoted cell proliferation, whereas inhibition of Shh by cyclopamine, a specific inhibitor of Shh signalling, had an opposite effect. Interestingly, the mitogenic effect of epidermal growth factor (EGF) on HPESCs was efficiently abolished by cyclopamine. Finally, bone morphogenetic protein 4 (BMP-4), a potential downstream effector of Shh signalling, increased HPESC proliferation in a concentration-dependent manner.

CONCLUSIONS

Shh is an important regulator of HPESC proliferation in the basal layer of human fetal epidermis and modulates the cell responsiveness to EGF, which will assist to unravel the mechanisms that regulate stem cell proliferation and neoplasia in the human epidermis.

Directing stem cells into the keratinocyte lineage in vitro

A major area of research in regenerative medicine is the potential application of stem cells in skin grafting and tissue engineering. This would require well defined and efficient protocols for directing the commitment and differentiation of stem cells into the keratinocyte lineage, together with their selective purification and proliferation in vitro. The development of such protocols would reduce the likelihood of spontaneous differentiation of stem cells into divergent lineages upon transplantation, as well as reduce the risk of teratoma formation in the case of embryonic stem cells. Additionally, such protocols could provide useful in vitro models for studying skin tissue biology, as well as facilitate the genetic manipulation of stem cells for therapeutic applications. The development of pharmacokinetic and cytotoxicity/genotoxicity screening tests for skin-related biomaterials and drugs could also utilize protocols developed for the commitment and differentiation of stem cells into the keratinocyte lineage. Hence, this review critically examines the various strategies that could be employed to direct the commitment and differentiation of stem cells into the keratinocyte lineage in vitro.

Expression of Sonic hedgehog pathway genes is altered in colonic neoplasia

The Hedgehog (Hh) signalling pathway is crucial for normal development and patterning of numerous human organs including the gut. Hh proteins are also expressed during gastric gland development and gastric epithelial differentiation in adults. Recently, dysregulation of these developmentally important genes has been implicated in cancer, leading to the present study of the expression of Hh signalling proteins in colon cancer. In this study, normal colon and colonic lesions (hyperplastic polyp, adenoma, and colonic adenocarcinoma) were examined by immunohistochemistry using antibodies against Hh signalling molecules: the secreted protein Sonic hedgehog (SHH), its receptor Patched (PTCH), and the PTCH-associated transmembrane protein Smoothened (SMOH). The study shows that Hh signalling pathway members are expressed in normal colonic epithelium. SHH was expressed at the top of the crypts and in a few basally located cells, while PTCH was detected in the neuroendocrine cells and SMOH at the brush border of superficial epithelium. RT-PCR analysis of laser-microdissected crypts from normal human colon confirmed that mRNAs encoding these proteins were expressed in colonic epithelium. Expression of SHH, PTCH, and SMOH was up-regulated in hyperplastic polyps, adenomas, and adenocarcinomas of the colon, and SHH expression correlated with increased expression of the proliferation marker Ki-67 in all lesions examined. To address whether the Hh signalling pathway is functional in the gut, the effect of Shh on epithelial cells in vitro was explored by treating primary murine colonocytes with either Shh peptide or neutralizing anti-Shh antibody. The proportion of cells in the S-phase was assessed by bromodeoxyuridine (BrdU) incorporation. It was found that exogenous Shh promotes cell proliferation in colonocytes, while anti-Shh inhibits proliferation, suggesting that Shh is required during proliferation of epithelial cells in vitro. It is suggested that SHH is required during epithelial proliferation in the colon and that there is a possible role for Hh signalling in epithelial colon tumour progression in vivo.

Functional analysis of novel sonic hedgehog gene mutations identified in basal cell carcinomas from xeroderma pigmentosum patients

Altered sonic hedgehog (SHH) signaling is crucial in the development of basal cell carcinomas (BCC), the most common human cancer. Mutations in SHH signal transducers, PATCHED and SMOOTHENED, have already been identified, but SHH mutations are extremely rare; only 1 was detected in 74 sporadic BCCs. We present data showing unique SHH mutations in BCCs from repair-deficient, skin cancer-prone xeroderma pigmentosum (XP) patients, which are characterized by high levels of UV-specific mutations in key genes involved in skin carcinogenesis, including PATCHED and SMOOTHENED. Thus, 6 UV-specific SHH mutations were detected in 5 of 33 XP BCCs. These missense SHH alterations are not activating mutations for its postulated proto-oncogene function, as the mutant SHH proteins do not show transforming activity and induce differentiation or stimulate proliferation to the same level as the wild-type protein. Structural modeling studies of the 4 proteins altered at the surface residues, G57S, G64K, D147N, and R155C, show that they do not effect the protein conformation. Interestingly, they are all located on one face of the compact SHH protein suggesting that they may have altered affinity for different partners, which may be important in altering other functions. Additional functional analysis of the SHH mutations found in vivo in XP BCCs will help shed light on the role of SHH in skin carcinogenesis. In conclusion, we report for the first time, significant levels of SHH mutations found only in XP BCCs and none in squamous cell carcinomas, indicating their importance in the specific development of BCCs.