Aberrant overexpression of an epithelial marker, 14-3-3σ, in a subset of hematological malignancies

<p>Abstract</p> <p>Background</p> <p>14-3-3σ is a p53-mediated cell-cycle inhibitor in epithelial cells. The expression of 14-3-3σ is frequently altered in cancers of epithelial origin associated with altered DNA methylation. Since its involvement in a non-epithelial tumor is unknown, we examined 14-3-3σ expression in patients with haematological malignancies.</p> <p>Methods</p> <p>We analyzed 41 hematopoietic cell lines and 129 patients with a variety of hematological malignancies for 14-3-3σ expression with real-time RT-PCR. We also examined protein levels by Western blot analysis and DNA methylation status of the 14-3-3σ gene by methylation-specific PCR analysis of bisulfite-treated DNA. In addition, mutations of p53 gene were identified by RT-PCR-SSCP analysis and the expression levels of 14-3-3σ were compared with those of other cell-cycle inhibitor genes, CDKN2A and ARF.</p> <p>Results</p> <p>The expression levels of 14-3-3σ mRNA in almost all cell lines were low and comparable to those in normal hematopoietic cells except for 2 B-cell lines. On the contrary, 14-3-3σ mRNA was aberrantly overexpressed frequently in mature lymphoid malignancies (30 of 93, 32.3%) and rarely in acute leukemia (3 of 35, 8.6%). 14-3-3σ protein was readily detectable and roughly reflected the mRNA level. In contrast to epithelial tumors, methylation status of the 14-3-3σ gene was not associated with expression in hematological malignancies. Mutations of p53 were identified in 12 patients and associated with lower expression of 14-3-3σ. The expression levels of 14-3-3σ, CDKN2A and ARF were not correlated with but rather reciprocal to one another, suggesting that simultaneous overexpression of any two of them is incompatible with tumor growth.</p> <p>Conclusion</p> <p>14-3-3σ, an epithelial cell marker, was overexpressed significantly in a subset of mature lymphoid malignancies. This is the first report of aberrant 14-3-3σ expression in non-epithelial tumors <it>in vivo</it>. Since the significance of 14-3-3σ overexpression is unknown even in epithelial tumors such as pancreatic cancers, further analysis of regulation and function of the 14-3-3σ gene in non-epithelial as well as epithelial tumors is warranted.</p

Frequent downregulation of 14-3-3 σ protein and hypermethylation of 14-3-3 σ gene in salivary gland adenoid cystic carcinoma

14-3-3 σ, a target gene of the p53 tumour suppressor protein, has been shown to regulate the cell cycle at the G2/M checkpoint. Recent studies have demonstrated that 14-3-3 σ is downregulated by hypermethylation of the CpG island in several types of cancer. In this study, we investigated the expression and methylation status of 14-3-3 σ in human salivary gland adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). Immunohistochemical analysis revealed that the positive expression rate of 14-3-3 σ in ACC (one out of 14) was markedly lower than that in MEC (ten out of 10). Since most of the ACCs carried the wild-type p53 protein, downregulation of 14-3-3 σ in ACC may not be due to the dysfunction of p53 pathway. Microdissection–methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 σ gene was observed in ACC when compared to that in MEC. In cultured-ACC cells, we confirmed the downregulation of 14-3-3 σ via hemimethylation of the gene by sequencing analysis after sodium bisulphite treatment. Furthermore, re-expression of 14-3-3 σ in the ACC cells was induced by the treatment with DNA demethylating agent, 5-aza-2′-deoxycytidine. Irradiation apparently induced the enhanced expression of 14-3-3 σ and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 σ nor G2/M arrest was induced by irradiation. These results suggest that downregulation of 14-3-3 σ might play critical roles in the neoplastic development and radiosensitivity of ACC

A new class of glycomimetic drugs to prevent free fatty acid-induced endothelial dysfunction

Background: Carbohydrates play a major role in cell signaling in many biological processes. We have developed a set of glycomimetic drugs that mimic the structure of carbohydrates and represent a novel source of therapeutics for endothelial dysfunction, a key initiating factor in cardiovascular complications. Purpose: Our objective was to determine the protective effects of small molecule glycomimetics against free fatty acid­induced endothelial dysfunction, focusing on nitric oxide (NO) and oxidative stress pathways. Methods: Four glycomimetics were synthesized by the stepwise transformation of 2,5­dihydroxybenzoic acid to a range of 2,5­substituted benzoic acid derivatives, incorporating the key sulfate groups to mimic the interactions of heparan sulfate. Endothelial function was assessed using acetylcholine­induced, endotheliumdependent relaxation in mouse thoracic aortic rings using wire myography. Human umbilical vein endothelial cell (HUVEC) behavior was evaluated in the presence or absence of the free fatty acid, palmitate, with or without glycomimetics (1µM). DAF­2 and H2DCF­DA assays were used to determine nitric oxide (NO) and reactive oxygen species (ROS) production, respectively. Lipid peroxidation colorimetric and antioxidant enzyme activity assays were also carried out. RT­PCR and western blotting were utilized to measure Akt, eNOS, Nrf­2, NQO­1 and HO­1 expression. Results: Ex vivo endothelium­dependent relaxation was significantly improved by the glycomimetics under palmitate­induced oxidative stress. In vitro studies showed that the glycomimetics protected HUVECs against the palmitate­induced oxidative stress and enhanced NO production. We demonstrate that the protective effects of pre­incubation with glycomimetics occurred via upregulation of Akt/eNOS signaling, activation of the Nrf2/ARE pathway, and suppression of ROS­induced lipid peroxidation. Conclusion: We have developed a novel set of small molecule glycomimetics that protect against free fatty acidinduced endothelial dysfunction and thus, represent a new category of therapeutic drugs to target endothelial damage, the first line of defense against cardiovascular disease

The Secretome of Aged Fibroblasts Promotes EMT-Like Phenotype in Primary Keratinocytes from Elderly Donors through BDNF-TrkB Axis

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Role of Nicotinamide in Genomic Stability and Skin Cancer Chemoprevention

Nicotinamide (NAM) is an amide form of vitamin B3 and the precursor of nicotinamide adenine dinucleotide (NAD+), an essential co-enzyme of redox reactions for adenosine triphosphate (ATP) production and for other metabolic processes. As NAD+ status is critical in maintaining cellular energy, vitamin B3 deficiency mainly affects tissues that need high cellular energy causing pellagra and skin sun sensitivity. In animal models, NAD+ deficiency leads to UV sensitivity of the skin, impairs DNA damage response, and increases genomic instability and cancer incidence. Furthermore, NAD+ depletion is associated with human skin aging and cancer. NAM prevents the UV-induced ATP depletion boosting cellular energy and enhances DNA repair activity in vitro and in vivo. Moreover, NAM reduces skin cancer incidence and prevents the immune-suppressive effects of UV in mice. Thus, NAM is involved in the maintenance of genomic stability and may have beneficial effects against skin aging changes and tumor development. Clinical studies showed that topical use of NAM reduces cutaneous aging. Furthermore, oral NAM administration reduces the level of UV-mediated immunosuppression and lowers the rate of non-melanoma skin cancers in high-risk patients. Therefore, NAM replenishment strategy may be a promising approach for skin cancer chemoprevention

Keratinocyte-mediated cell and gene therapy

Although some markers for the epidermal stem cell compartment have been proposed, their role in specifically identifying keratinocyte stem cells is still controversial. Therefore, the identification of surface epithelial stem cells relies on either the evaluation of their proliferative capacity or on the identification of slow cycling, [3H]TdR- and BrdU-retaining cells, the latter being feasible only on laboratory animals. The proliferative capacity of human lining epithelial stem cells can be evaluated in vitro by means of clonal analysis. Indeed, three types of keratinocytes with different capacities for multiplication have been identified and isolated in human epidermis, hair follicle, limbal-corneal and conjunctival epithelia, i.e. holoclones, meroclones and paraclones. The authors have recently demonstrated that cultured autografts bearing holoclones can indeed rapidly and permanently cover a large body surface. Preparation of the wound bed and maintenance of epidermal stem cells in culture are found to be crucial to the clinical success of the technology. The implications and clincial results of permanent coverage of massive full-thickness burns, treatment of "stable" vitiligo with cultured epidermal autografts and permanent coverage of damaged ocular surfaces after complete loss of the corneal-limbal epithelium as well as ex vivo gene therapy of junctional epidermolysis bullosa are reported in this study and literature review. Basic "quality controls" of the culture system may eliminate one important hitherto uncontrolled variable in the evaluation of cultured autograft clinical performance and should represent a starting point for improving epithelial cultivation, in order to achieve satisfactory and reproducible clinical result

Toward gene therapy of junctional epidermolysis bullosa (JEB)

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Toward epidermal stem cell-mediated ex vivo gene therapy of junctional epidermolysis bullosa

Junctional epidermolysis bullosa (JEB) is a group of severe, inherited skin diseases caused by mutations in the genes encoding laminin 5 or other components of the hemidesmosome. Since human epidermis is a self-renewing tissue, gene therapy of JEB requires the stable integration of the transgene into the genome of the epidermal stem cell. Human epidermal stem cells can indeed be cultivated and stably transduced with replication-defective retroviral vectors, allowing full phenotypic correction of the adhesion properties of JEB keratinocytes. Epidermal stem cells generate cohesive sheets of stratified epithelium suitable for the permanent coverage of massive skin defects, and genetically modified epidermal sheets maintain long-term expression of the transgene after transplantation on immunodeficient animals. Moreover, we have developed a clinical procedure that allows transplantation of cultured epidermal sheets on large body areas under local anesthesia and without cicatricial outcomes. Thus, (1) the possibility of cultivating lining epithelia, (2) the availability of noninvasive surgical procedures that allow the grafting of large skin areas, and (3) the demonstration of sustained transgene expression in vitro and in vivo by epidermal stem cells, prompt us to propose the implementation of a phase I/II clinical trial aimed at the ex vivo gene therapy of selected JEB patients. The aim of the trial is to validate the ex vivo procedure in a clinical setting, to prove its overall safety, and to analyze critical issues such as long-term survival of the genetically modified implant, immune response against the transgene product, and persistence of transgene expression at therapeutic levels.PMID: 11084687 [PubMed - indexed for MEDLINE