Proliferative activity and p53 expression in primary and recurrent pterygia

doi:10.1016/S0161-6420(00)00651-5

Ophthalmology

Volume 108, Issue 5, May 2001, Pages 985-988

Presented in part at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, May 1999.

https://doi.org/10.1016/S0161-6420(00)00651-5 Get rights and content

Abstract

Purpose

To assess p53 expression and proliferative activity in primary and recurrent pterygia from the same eyes.

Design

Retrospective comparative human tissue study.

Participants

Tissue from excised primary pterygia that did not recur (group A, n = 10) was compared with tissue from primary pterygia that recurred (group B, n = 10) and to the recurrent pterygia tissue that was excised from subjects in group B (group C, n = 10). Ten normal conjunctivas served as controls (group D).

Methods

Sections from each pterygium were immunostained with the MIB-1 and bp53. 12 monoclonal antibodies that react with Ki-67 and p53 antigens, respectively.

Main outcome measures

Proliferative activity was calculated as the mean of the MIB-1 positive cell count per eyepiece grid in high magnification (×40) (positive cell count/grid). Percentage of positive cells of all cells in the grid area was evaluated in the p53-stained sections.

Results

Proliferative activity was found in the epithelium overlying the pterygia and normal conjunctiva. The mean MIB-1 positive cell count/grid ± standard error was 2.84 ± 1.07, 1.74 ± 0.82, 3.83 ± 1.35, and 0.86 ± 0.33 in groups A, B, C, and D, respectively (P = 0.17, Kruskal-Wallis). P53 staining was found in 50% of pterygia in groups A, B, and C; none of the normal conjunctival tissues showed p53 immunoreactivity. Four of five p53-positive tissues in group B were p53-negative in group C. In the p53-positive pterygia, less than 10% of cells were p53 positive. However, p53-positive pterygia had higher mean MIB-1 positive cell count/grid ± standard error as compared with the p53-negative lesions, 4.56 ± 0.94 vs 1.39 ± 0.59 (P = 0.021, Mann–Whitney).

Conclusions

p53 immunoreactivity and high proliferative activity in the epithelium overlying the pterygium are not associated with recurrence of pterygium.

Section snippets

Subjects and methods

Formalin-fixed, paraffin-embedded sections of pterygium and conjunctival tissues from the ophthalmic pathology laboratory at the Hadassah University Hospital, Jerusalem, Israel, were used for the study. Subjects who underwent pterygium removal without mitomycin-C application, and who were prospectively followed for more than 12 months, were included in the study. Four groups of pterygia were studied. Pterygium tissue from 10 consecutive patients who did not have recurrence of the

Results

MIB-1 yielded a red nuclear stain in epithelial cells from all the tissue in all groups (Fig 1A). There was no significant difference among the proliferative activities of the four groups as estimated by the mean MIB-1 positive cell count per eyepiece grid (P = 0.17, Kruskal-Wallis test). However, there was a trend toward higher proliferative activity in epithelium overlying the pterygium compared with normal conjunctival epithelium (mean MIB-1 positive cell count/grid ± standard error was

Discussion

We found p53 immunoreactivity in half of the primary (groups A and B) and recurrent (group C) pterygia. Interestingly, we did not find a difference in p53 immunoreactivity between eyes with primary pterygium that did not recur and primary pterygium that was followed by recurrence of the pterygium. Most of the recurrences of primary p53-positive pterygia were p53 negative. In addition, proliferative activity of primary pterygia that recurred (group B) was similar to that of primary pterygia

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The roles of mouse double minute 2 (MDM2) oncoprotein in ocular diseases: A review
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Citation Excerpt :
These p53 mutations are thought to be also involved in the pathogenesis of pterygium, which is similarly associated with the environmental risk factor of UV exposure. For example, immunohistochemical studies have identified mutant p53 (Dushku and Reid, 1997; Tsai et al., 2005b; Ueda et al., 2001) or aberrant expression of p53 (Chowers et al., 2001; Tan et al., 2000; Tsai et al., 2005a; Weinstein et al., 2002) in pterygium specimens. Reisman et al. (2004) reported monoallelic deletion of the p53 gene in a significant proportion (44.4%) of pterygium cases; however, the remaining WT p53 allele was silenced by an unknown mechanism.
Mouse double minute 2 (MDM2), an E3 ubiquitin ligase and the primary negative regulator of the tumor suppressor p53, cooperates with its structural homolog MDM4/MDMX to control intracellular p53 level. In turn, overexpression of p53 upregulates and forms an autoregulatory feedback loop with MDM2. The MDM2-p53 axis plays a pivotal role in modulating cell cycle control and apoptosis. MDM2 itself is regulated by the PI3K-AKT and RB-E2F-ARF pathways. While amplification of the MDM2 gene or overexpression of MDM2 (due to MDM2 SNP T309G, for instance) is associated with various malignancies, numerous studies have shown that MDM2/p53 alterations may also play a part in the pathogenetic process of certain ocular disorders. These include cancers (retinoblastoma, uveal melanoma), fibrocellular proliferative diseases (proliferative vitreoretinopathy, pterygium), neovascular diseases, degenerative diseases (cataract, primary open-angle glaucoma, age-related macular degeneration) and infectious/inflammatory diseases (trachoma, uveitis). In addition, MDM2 is implicated in retinogenesis and regeneration after optic nerve injury. Anti-MDM2 therapy has shown potential as a novel approach to treating these diseases. Despite major safety concerns, there are high expectations for the clinical value of reformative MDM2 inhibitors. This review summarizes important findings about the role of MDM2 in ocular pathologies and provides an overview of recent advances in treating these diseases with anti-MDM2 therapies.
MicroRNA regulation of MDM2-p53 loop in pterygium
2018, Experimental Eye Research
Citation Excerpt :
To date, over 20 studies have reported p53 expression in pterygium by immunochemistry analysis, but the quantitative results were inconsistent. The proportion of pterygial samples with positive p53 expression was detected as 7.9% (Onur et al., 1998), 22.8% (Tsai et al., 2005), 37.5% (Tan et al., 1997), 50% (Chowers et al., 2001), 53.8% (Weinstein et al., 2002), 60% (Tan et al., 2000) and 100% (Dushku et al., 1999), respectively. One possible reason causing such varied results could be the sources and sensitivity of different anti-p53 antibodies.
The pathogenesis of pterygium has been linked to limbal stem cell damage, abnormal apoptosis and cellular proliferation. In this study, we investigated the epigenetic regulation through microRNA expression in the pathogenesis of pterygium.
Human full-length primary pterygia were microdissected into head and body regions. Specific microRNA and mRNA expression was assayed by TaqMan^® real-time quantitative polymerase chain reaction (qPCR). Tissue localization of target microRNAs was performed by LNA-based in situ hybridization. MicroRNA-145 (miR-145) mimics were transfected to primary culture of human pterygial cells, followed by analyses of cell cycle changes, apoptosis, p53 and MDM2 expression using flow cytometry and qPCR.
The expression of miR-145 was markedly higher in primary human pterygium than in limbus and conjunctiva. Both miR-143 and miR-145 were predominantly expressed in the basal pterygial epithelium. Oncogene MDM2 expression was abundant in pterygial epithelium and stroma, while the expression pattern was opposite to that of miR-145. Ectopic expression of miR-145 in pterygial cells induced G1 arrest, down-regulated MDM2 and elevated p53 expression.
Our study showed that miR-145 suppressed MDM2 expression, which subsequently influenced the p53-related cell growth pattern in pterygial epithelium. The regulatory miR-145/MDM2-p53 loop can serve as a potential target for treatment of pterygium.
Inactivation of p53 in pterygium influence miR-200a expression resulting in ZEB1/ZEB2 up-regulation and EMT processing
2016, Experimental Eye Research
Citation Excerpt :
Nearly all reported studies of the p53 gene in pterygia have been conducted using immunohistochemistry (IHC) staining (Weinstein et al., 2002; Tan et al., 2000; Ueda et al., 2001). Previous studies have shown that the p53 gene mutation ranges widely in pterygia, from 7.9% to 100% (Weinstein et al., 2002; Tan et al., 2000; Ueda et al., 2001; Chowers et al., 2001). Our previous research also showed that mutations in p53 genes were detected in 15.7% of pterygial samples (8 of 51) (Tsai et al., 2005).
Loss of p53 function has been linked to progression of pterygium. MiR-200a is known to be controlled by p53. Here, we hypothesize that expression of miR-200a and downstream ZEB1/ZEB2 genes are regulated epithelial–mesenchymal transition (EMT) involved in the pathogenesis and recurrence of pterygium. For this study, 120 primary pterygial samples were collected. Immunohistochemistry and real-time RT-PCR were performed to determine the expression of p53, p53 down-stream EMT associated protein and miR-200a. The molecular correlation of p53, miR-200a and downstream genes were confirmed using primary pterygium cells (PECs). Expression of miR-200a in pterygium tissues was significantly lower than in conjunctiva controls (p = 0.015). Up-regulated miR-200a levels were positively correlated with and p53 protein expression (p < 0.001). The miR-200a downstream ZEB1/ZEB1 protein expression were negative correlated with miR-200a expression. Cell model studies demonstrated that miR-200a controlled the EMT of PECs through up-regulated ZEB1, ZEB2 and Snail gene expression. Our study demonstrated that inactivation of p53 in pterygium may influence miR-200a, resulting in ZEB1/ZEB2 up-regulation and EMT processing of pterygium. Therefore, we suggest that expression of miR-200a play an important role in EMT processing and recurrence of pterygium.
Fibroblast biology in pterygia
2016, Experimental Eye Research
Citation Excerpt :
Thus, the stromal fibroblast which is responsible for tissue remodeling during the wound healing may be a main culprit of fibrosis in recurrent pterygia. Interestingly, positive p53 expression and high proliferative activity in the epithelium of pterygia were found not associated with recurrence (Chowers et al., 2001). On the contrary, b-FGF was strongly expressed in cultured fibroblasts of recurrent pterygia compared to those of primary pterygia suggesting that fibroblasts might have a major role in the recurrence (Kria et al., 1998).
Activation of fibroblasts is a vital process during wound healing. However, if prolonged and exaggerated, profibrotic pathways lead to tissue fibrosis or scarring and further organ malfunction. Although the pathogenesis of pterygium is known to be multi-factorial, additional studies are needed to better understand the pathways initiated by fibroblast activation for the purpose of therapeutic translation. Regarding pterygium as a possible systemic disorder, we discuss the different cell types that pterygium fibroblasts originate from. These may include bone marrow-derived progenitor cells, cells undergoing epithelial–mesenchymal transition (EMT), and local resident stromal cells. We also describe how pterygium fibroblasts can be activated and perpetuate profibrotic signaling elicited by various proliferative drivers, immune-inflammation, and novel factors such as stromal cell-derived factor-1 (SDF-1) as well as a known key fibrotic factor, transforming growth factor-beta (TGF-β). Finally, epigenetic modification is discussed to explain inherited susceptibility to pterygium.
Effect of orbital protrusion and vertical interpalpebral distance on pterygium formation
2014, Contact Lens and Anterior Eye
Citation Excerpt :
Heat, dry atmospheric conditions, wind, dust and similar factors have been found to be responsible in many research studies [2–4]. As well as environmental factors, hereditary factors, tear dysfunction, immunological mechanisms, viral infections such as human papillomavirus (HPV) and herpes simplex virus (HSV), chronic inflammation, various occupations and p53 tumor suppressor gene abnormalities have been shown to be related in pterygium etiology [2,5–7]. There are a many studies showing that ultraviolet B (UV-B) light in particular has a distinctive role in the pterygium pathogenesis [8–12].
To evaluate the risk factors in the development of pterygium in the Marmara region of Turkey as well as the efficacy of vertical interpalpebral distance, protrusion level and tear function in the development of pterygium.
The cases were grouped in two as the research group consisted of patients with pterygium and the control group consisted of healthy people. A total of 294 patients with pterygium (108 bilateral, 186 unilateral) and 200 controls were included in the study. All patients and control group underwent a thorough ophthalmic examination, including tear function analysis using tear film breakup time measurement, protrusion level and vertical interpalpebral distance.
No statistically significant difference was found between the bilateral pterygium subgroup and control group in terms of vertical interpalpebral distance and protrusion value (p = 0.733, p = 0.625). When the pterygium eyes and the control group were compared in the unilateral pterygium subgroup, no significant difference was found in terms of vertical interpalpebral distance and protrusion value (p = 0.533, p = 0.209).
While UV efficiency in pterygium was obvious, protrusion value and vertical interpalpebral distance were not found to be a risk factor in the formation of pterygium.
Pterygium
2013, Ocular Surface Disease: Cornea, Conjunctiva and Tear Film

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Proliferative activity and p53 expression in primary and recurrent pterygia

Abstract

Purpose

Design

Participants

Methods

Main outcome measures

Results

Conclusions

Section snippets

Subjects and methods

Results

Discussion

Ophthalmology

Ophthalmology

Am J Ophthalmol

Cell

Solar keratosis, pterygium, and squamous cell carcinoma of the conjunctiva in Malawi

Br J Ophthalmol

Meta-analysis on the recurrence rates after bare sclera resection with and without mitomycin C use and conjunctival autograft placement in surgery for primary pterygium

Br J Ophthalmol