Adenoviral p53 gene transfer inhibits human Tenon's capsule fibroblast proliferation

Cloning of Hynobius lichenatus (Tohoku hynobiid salamander) p53 and analysis of its expression in response to radiation

Background

Caudata species such as salamanders are easily affected by environmental changes, which can drastically reduce their population. The effects of acute X-rays and chronic γ-irradiation on Hynobius lichenatus, the Japanese Tohoku hynobiid salamander, are known. However, the expression of radiation-inducible genes, such as the DNA-damage checkpoint response gene p53, has not been analyzed in H. lichenatus. This has not occurred because there is no established method for mRNA quantification in H. lichenatus due to a lack of information on available nucleotide sequences corresponding to both radiation-inducible genes and endogenous control genes such as ACTB (β-actin).

Results

In this study, we aimed to evaluate the effects of radiation on gene expression in H. lichenatus. Using RNA extracted from irradiated salamanders, we performed rapid amplification of cDNA ends (RACE) and cloned H. lichenatus β-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and p53. We confirmed that the cloned cDNAs were able to synthesize salamander proteins by western blotting after transfection into cultured HEK293 cells. Proliferation assays using HEK293 cells stably expressing H. lichenatus p53 protein showed that this protein has antiproliferative effects, similar to that of mammalian p53. Furthermore, RT-qPCR analysis using gene-specific primers revealed that p53 mRNA expression in H. lichenatus was upregulated upon exposure to radiation.

Conclusion

Our results suggest that H. lichenatus p53 protein take an important role in regulating the cellular responses to various stimuli as mammalian p53 does. Furthermore, our study provides novel data to select appropriate primers to analyze internal control mRNA expression in H. lichenatus and to evaluate p53 expression as a marker of radiation and environmental stimuli.

Glaucomagenesis following ionizing radiation exposure

Glaucoma is a group of optic neuropathies causing optic nerve damage and visual field defects, and is one of the leading causes of blindness. Nearly a century has passed since the first report of glaucoma manifested following ionizing radiation therapy of cancers. Nevertheless, associations between glaucoma and radiation exposures, a dose response relationship, and the mechanistic underpinnings remain incompletely understood. Here we review the current knowledge on manifestations and mechanisms of radiogenic glaucoma. There is some evidence that neovascular glaucoma is manifest relatively quickly, within a few years after high-dose and high dose-rate radiotherapeutic exposure, but little evidence of excess risks of glaucoma after exposure to much lower doses or dose rates. As such, glaucoma appears to have some of the characteristics of a tissue reaction effect, with a threshold of at least 5 Gy but possibly much higher.

Key points of basic theories and clinical practice in rAd-p53 ( Gendicine ™) gene therapy for solid malignant tumors

INTRODUCTION

Wild-type p53 gene is an essential cancer suppressor gene which plays an important role in carcinogenesis and malignant progressions. The p53 gene family participates in almost all the key procedures of cancer biology, such as programmed cell death, angiogenesis, metabolism and epithelial-mesenchymal transition. The mutation or functional defects of the p53 gene family are detected in most of the solid malignant tumors, and the restoration of the p53 gene by adenovirus-mediated gene therapy becomes a promising treatment for cancer patients now.

AREAS COVERED

In the present review, the potential therapeutic effects of recombinant adenovirus p53 rAd-p53 ( Gendicine ™) were reviewed to explore the biological mechanism underlying the adenovirus-mediated p53 gene therapy. Then, the key points of the drug administration were discussed, including the routes of administration, dosage calculation and treatment cycles, based on findings of the preclinical and clinical trials in order to establish a standard treatment for the p53 gene therapy.

EXPERT OPINION

As an important part of the combined therapy for the cancer patients, the adenovirus-mediated p53 gene therapy was blossomed to be a promising treatment strategy. A new evaluation criteria and guideline for the gene therapy is urgently needed for the further clinical practice.

Developing novel anti-fibrotic therapeutics to modulate post-surgical wound healing in glaucoma: big potential for small molecules

Ocular fibrosis leads to significant visual impairment and blindness in millions of people worldwide, and is one of the largest areas of unmet need in clinical ophthalmology. The antimetabolites, mitomycin C and 5-fluorouracil, are the current gold standards used primarily to prevent fibrosis after glaucoma surgery, but have potentially blinding complications like tissue damage, breakdown and infection. This review thus focuses on the development of new classes of small molecule therapeutics to prevent post-surgical fibrosis in the eye, especially in the context of glaucoma filtration surgery. We discuss recent advances and innovations in ophthalmic wound healing research, including antibodies, RNAi, gene therapy, nanoparticles, liposomes, dendrimers, proteoglycans and small molecule inhibitors. We also review the challenges involved in terms of drug delivery, duration of action and potential toxicity of new anti-fibrotic agents in the eye.

Wound modulation after filtration surgery

Filtration surgery is the standard invasive procedure for the management of intraocular pressure in advanced glaucoma. The key to a successful outcome is to modulate the normal wound healing cascade that leads to closure of the newly created aqueous outflow pathway. Antifibrotic agents such as mitomycin C and 5-fluorouracil have been increasingly used to modulate the wound healing process and increase surgical success. Although these agents have proven efficacy, they also increase the risk of complications. Efforts have centered on the identification of novel agents and techniques that can influence wound modulation without these complications. We detail new agents and methods under investigation to control wound healing after filtration surgery.

Small interfering RNA targeting of S phase kinase-interacting protein 2 inhibits cell proliferation of pterygium fibroblasts

PURPOSE

Fibroblast cell proliferation is major reason for recurrence of pterygia. In the present study, we investigated if small interfering RNA (siRNA)-mediated gene silencing of S phase-kinase-interacting protein 2 (Skp2) can be employed to inhibit protein 27 kinase inhibition protein 1 (p27(kip1)) down-regulation in pterygium fibroblast cells (PFC) in vitro and in vivo.

METHODS

A plasmid containing transgenes encoding Skp2 siRNA was used to decreasing the high constitutive levels of Skp2 protein in PFC and normal fibrboblast cells (NFC) in vitro and in vivo which can lead to consequent degradation of p27(kip1). Cell proliferation and viability were investigated using cell counts, 59-bromodeoxyuridine incorporation (BrdU assay) and tetrazolium reduction (MTT assay).

RESULTS

Infection of PFC and NFC with Skp2 siRNA resulted in significant inhibition of cell proliferation and metabolic activity in vitro. Immunoflurescence showed decreased levels of Skp2 and increased levels of p27(kip1) in pSkp2 siRNA infected cells, but not in plasmid and uninfected cells.

CONCLUSIONS

Skp2 siRNA inhibited the cell proliferation of PFC in vitro and in vivo.

Inhibition of proliferation of rabbit lens epithelial cells by S-phase kinase-interacting protein 2 targeting small interfering RNA

PURPOSE

Improper proliferation of lens epithelial cells is causally related to posterior capsule opacification. In the present study, we investigated whether small interfering RNA (siRNA)-mediated gene silencing of S-phase kinase-interacting protein 2 (Skp2) can be employed to inhibit rabbit lens epithelial cell (rLEC) proliferation by increasing the p27(kip1) level.

METHODS

A plasmid containing Skp2 siRNA was used to decrease the high constitutive level of Skp2 protein in rLECs, which can lead to consequent degradation of p27(kip1). Protein expression of Skp2 and p27(kip1) was detected by immunocytochemistry and western blot. Cell viability was measured using the tetrazolium reduction (3-(4,5-dimethylthiazolyl-2-)-2,5-diphenyltetrazoliumbromide [MTT]) assay. Cell proliferation was assayed by cell counts, immunocytochemistry, and western blot by using antibodies against proliferating cell nuclear antigen.

RESULTS

Immunocytochemistry and western blot showed a decreased level of Skp2 and increased level of p27(kip1) in cells transfected with pSkp2 siRNA but not in vehicle transfection and uninfected cells. MTT assay showed that cell viability significantly declined in rLECs transfected with Skp2 siRNA. Skp2 siRNA transfected cells showed significantly less 59-bromodeoxyuridine- and proliferating cell nuclear antigen-positive staining compared with control cells.

CONCLUSIONS

Skp2 siRNA inhibits cell proliferation and decreases cell viability of rLECs in vitro by suppression of p27(kip1) downregulation. Our findings suggest that siRNA-mediated gene silencing of Skp2 can be a novel gene therapy for posterior capsule opacification induced by LEC abnormal proliferation.

In vitro and clinical studies of gene therapy with recombinant human adenovirus-p53 injection for oral leukoplakia

PURPOSE

Oral leukoplakia is a well-recognized precancerous lesion of squamous cell carcinoma. When accompanied with abnormal p53 expression, it suffered a higher risk of canceration. The present study was carried out to test whether the recombinant human adenovirus-p53 could introduce wild-type p53 gene to oral leukoplakia cells and induce cell cycle arrest and apoptosis.

EXPERIMENTAL DESIGN

We select p53(-) oral dysplastic keratinocyte POE-9n, to observe the growth inhibition, cell cycle change, apoptosis-induced effects, and elaborate the corresponding molecular mechanism of recombinant adenovirus-p53 on POE-9n cells. Meanwhile, we evaluate the feasibility, safety, and biological activity of multipoints intraepithelial injections of recombinant adenovirus-p53 in 22 patients with dysplastic oral leukoplakia.

RESULTS

Exogenous p53 could be successfully transduced into POE-9n cells by recombinant adenovirus-p53. The optimal infecting titer in this study was multiplicity of infection (MOI) = 100. Recombinant adenovirus-p53 could strongly inhibit cell proliferation, induce apoptosis, and arrest cell cycle in stage G(1) in POE-9n cells by inducing p21(CIP/WAF) and downregulating bcl-2 expression. In the posttreatment patients, p53 protein and p21(CIP/WAF) protein expression were significantly enhanced, yet bcl-2 protein presented low expression. Sixteen patients showed clinical response to the treatment, and 14 patients showed obvious histopathologic improvement.

CONCLUSION

Intraepithelial injections of recombinant human adenovirus-p53 were safe, feasible, and biologically active for patients with dysplastic oral leukoplakia.

Adenovirus-mediated delivery of p27(KIP1) to prevent wound healing after experimental glaucoma filtration surgery

AIM

The aim of the study was to evaluate the outcome of adenovirus-mediated p27(KIP1) (Ad-p27) expression on wound healing after filtration surgery and to investigate the inhibition of cell proliferation induced by Ad-p27.

METHODS

We constructed the adenovirus recombinant vector Ad-p27 and administered it to a rabbit model of glaucoma filtration surgery by subconjunctival injection; phosphate-buffered saline (PBS) and mitomycin C (MMC) were used as controls. Intraocular pressure (IOP), bleb scores, and anterior chamber depths were observed during a 28-d period. Histological examinations, fluorescence observations and Western blot analyses were evaluated.

RESULTS

Ad-p27 enhanced the surgical outcome and inhibited cell proliferation when compared with PBS. Bleb scores in the Ad-p27-treated eyes were higher than those in the PBS-treated eyes on d 7 (P<0.01), 14 (P<0.01) and 21 (P<0.05). On d 28, IOP remained significantly decreased in the Ad-p27 group compared with the PBS group (P<0.05). However, no differences in bleb scores or IOPs were observed between the Ad-p27 and MMC groups. Histological analysis showed that total cell numbers were markedly reduced, and less scar tissue was observed at the surgical site in eyes treated with Ad-p27. The number of fibroblasts was decreased in Tenon's capsule in Ad-p27-treated eyes; however, a marked and diffuse signal from the green fluorescent protein (GFP) was observed in fibroblasts. Western blot analysis revealed a high level of p27(KIP1) expression in conjunctival epithelium (P<0.01), relatively high expression in superficial scleral stroma (P<0.01), and low expression in corneal epithelium in the Ad-p27 group.

CONCLUSIONS

Ad-p27 administration significantly improves the outcome of filtration surgery and inhibits postoperative proliferation in rabbit eyes. These findings suggest that p27(KIP1) is a potential adjunctive agent for inhibition of wound healing after filtration surgery.

A novel bubble liposome and ultrasound-mediated gene transfer to ocular surface: RC-1 cells in vitro and conjunctiva in vivo

Gene therapy is a promising method; however, a potential risk of viral vector or low gene transfer efficacy of non-viral vector prevents it from clinical application for common diseases. The major obstacle in the clinical application of gene therapy is not due to the lack of an ideal gene, but rather the lack of a clinically safe and efficient gene transfer method. To complete a safe and effective gene transfer, we developed a novel bubble liposome (BL) with ultrasound (US) method. BL is composed of polyethylenglycol (PEG) modified liposome (PEGylated liposome) containing perfluoropropane gas, each of which independently has been used safely in human treatment and a PEGylated liposome is quite stable in vivo. Plasmids containing green fluorescent protein (GFP) cDNA were added to cultured rabbit corneal epithelial cells (RC-1, 2x10(5)cell/well and 5microl of a plasmid solution) followed by US exposure with BL (BL-US group). Similar experiments were conducted for US exposure-only (US-only group) and US exposure and conventional micro-bubble (MB-US group). Gene transfer efficacy was evaluated by immunofluorescent microscopy and the cell damage was analyzed by MTS assay. In an in vivo study, BL and plasmid were injected into rat subconjunctiva followed by US exposure (BLUS group, 1.2W/cm(2), 20s, duty cycle 50%) and GFP expression was evaluated by imaging (maximum +5 to minimum 0) for 8 days. Rats undergoing subconjunctival plasmid injection alone (injection group), plasmid injection and US exposure (US group), MB and plasmid injection and US exposure (MBUS group) were used as controls. Histological examination was conducted. BL and US exposure significantly increased gene transfer efficacy in cultured RC-1 cells (BL-US group, 27%; US-only group, 1%; MB-US group, 11%; P<0.05: ANOVA). Gene transfer was most prominent under the condition of US intensity of 1.2W/cm(2) with 21microg/well BL, duration 20s. No apparent cell damage was found in the BL-US group by MTS assay. In rat eyes, strong GFP staining was seen in conjunctiva of BLUS group (average: 3.6). It was significantly higher than in any of the following groups, injection group (average: 2.3), US group (average: 2.1), or MBUS group (average: 2.0; P=0.001, ANOVA). GFP-positive cells were mainly in the conjunctiva and no tissue damage was seen histologically. BL with US method effectively transfers genes to cultured corneal epithelial cells and rat subconjunctival tissue without causing any apparently adverse effect. This method would have a great advantage for gene therapy in ocular surface disease.

Gene transfer to trabecular meshwork endothelium via direct injection into the Schlemm canal and in vivo toxicity study

PURPOSE

Our aim was to investigate the efficiency of adenoviral gene transfer via direct injection into the Schlemm canal ex vivo in human donor eyes and to examine the effect of human MMP-3 transgene expression in a rat model in vivo.

METHODS

A viscocanalostomy-like operation was performed and adenoviral vector encoding for MMP-3 and green fluorescent protein was injected into human Schlemm canal or rat anterior chamber.

RESULTS

Transgene expression was high in trabecular meshwork endothelium in human donor eyes. In vivo, adenovirus caused dose-dependent inflammation.

CONCLUSIONS

Direct injection of adenoviral vectors into the Schlemm canal has potential in glaucoma treatment.