|Year : 2013 | Volume
| Issue : 4 | Page : 353-357
Evaluation of the immunoexpression of proinflammatory enzyme COX-2 and P53 gene in ulcerative colitis-associated dysplasia
Taher El-Demerdash1, Dina H Ziada1, Sahar El Yamany1, Hussien Ghoraba2, Eman Hasby2, Nahla Khalaf1
1 Department of Tropical Medicine, Faculty of Medicine, Tanta University, Tanta, Egypt
2 Department of Pathology, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||08-Aug-2013|
|Date of Acceptance||15-Sep-2013|
|Date of Web Publication||1-Feb-2014|
Dina H Ziada
Ass. Prof. of Tropical Medicine and Infectious Disease Department, Tanta Univeristy, Egypt, Al Gish Street, Tanta Univeristy Hospital, Tanta
Background and aim
Ulcerative colitis (UC) patients are at increased risk for colorectal dysplasia and colorectal cancer. The aim of this study was to analyze the expression alteration of proinflammatory enzyme cyclooxygenase-2 (COX-2) and the tumor-suppressor gene P53 to clarify whether these alterations may play a role in the pathogenesis of dysplasia, which is a precancerous lesion.
Patients and methods
This study was conducted on 40 individuals who were divided into three groups: 15 UC patients without dysplasia, 15 UC patients with dysplasia, and 10 participants with normal colonoscopy and histopathology as a control group.
There was a significant difference in the expression of Cox-2 and p53 in UC-related dysplasia compared with the UC group without dysplasia. There was a correlation between COX-2 and P53 expression and severity and duration of disease.
Addition of immunohistochemical analysis of Cox-2 enzyme and p53 gene to routine histologic assessment may improve the accuracy of early detection of dysplasia, which is a precancerous lesion, and thus decrease mortality from colorectal cancer.
Keywords: Cox-2 , p53, ulcerative colitis
|How to cite this article:|
El-Demerdash T, Ziada DH, El Yamany S, Ghoraba H, Hasby E, Khalaf N. Evaluation of the immunoexpression of proinflammatory enzyme COX-2 and P53 gene in ulcerative colitis-associated dysplasia. Tanta Med J 2013;41:353-7
|How to cite this URL:|
El-Demerdash T, Ziada DH, El Yamany S, Ghoraba H, Hasby E, Khalaf N. Evaluation of the immunoexpression of proinflammatory enzyme COX-2 and P53 gene in ulcerative colitis-associated dysplasia. Tanta Med J [serial online] 2013 [cited 2020 Jun 6];41:353-7. Available from: http://www.tdj.eg.net/text.asp?2013/41/4/353/126210
| Introduction|| |
Ulcerative colitis (UC) is a chronic, idiopathic inflammatory disorder of the large intestine, which is characterized by mucosal inflammation of the rectum that extends proximally through the colon in a continuous manner but to a variable extent  . The disease is associated with episodic periods of debilitating symptoms followed by asymptomatic intervals of remission. Although the exact cause of UC remains undetermined, the condition appears to be related to a combination of genetic and environmental factors. Diagnosis of UC is on the basis of a combination of clinical, laboratory, endoscopic, histological, and radiographic investigations. Patients with UC have a lifetime relative risk for colorectal cancer (CRC), which is 5-8 times higher than that in the normal population  , but the exact mechanism is still uncertain  . The term dysplasia refers to unequivocally neoplastic lesion occurring in the epithelium  .
Cyclooxygenase (Cox) is an enzyme important for the synthesis of prostaglandins. Cox-2 is highly inducible in response to cellular activation by hormones, proinflammatory cytokines, growth factors, and tumor promoters  . The overexpression of COX-2 in the epithelial cells as a consequence of inflammation leads to increased levels of bcl-2 and resistance to apoptosis (Sakamoto et al., 2005). The P53 gene is a tumor-suppressor gene and the most frequent site of genetic alterations found in human cancers; its mutation induces over half of the cancers  . Repeated and continuous inflammation and oxidative stress induce activation and overload of the P53 check point system, possibly resulting in P53 mutation  . The aim of this study was to analyze the expression alteration of proinflammatory enzyme cox-2 and the tumor-suppressor gene P53 to clarify whether these alterations may play a role in the pathogenesis of dysplasia, which is a precancerous lesion.
| Patients and methods|| |
An ethical approval from Tanta Ethical Committee, Faculty of Medicine, was taken before starting our study and written informed consent was taken from the studied patients. A total number of 40 participants were collected from the Department of Tropical Medicine and Hygiene, Tanta University. They were divided into three groups according to endoscopic and histopathological findings.
Group I included 15 UC patients without dysplasia.
Group II included 15 UC patients with dysplasia.
Group III included 10 individuals whose colonoscopic and histologic findings were normal.
All patients were subjected to complete history-taking and thorough clinical examination.
- Laboratory investigations were performed including blood tests (complete blood profile, liver function tests, erythrocyte sedimentation rate, blood urea, and serum creatinine) and stool analysis to exclude bacterial causes of colitis.
- Radiologic investigations were carried out, such as plain abdominal and pelvis radiographs and pelviabdominal ultrasound.
- Colonoscopy was performed in all groups under sedation after taking written consent.
An endoscopic scoring system for UC was used (Pineton et al., 2010).
Score 0: Normal or inactive disease.
Score 1: Mild disease (erythema, decreased vascular pattern, and mild friability).
Score 2: Moderate disease (marked erythema, absent vascular pattern, friability, and erosions).
Score 3: Severe disease (spontaneous bleeding and ulcerations).
Endoscopic findings were recorded and multiple biopsies were taken for histopathology.
Histopathological examination including hematoxylin and eosin and immunohistochemical staining were performed for COX-2 (rabbit polyclonal antibody) and P53 Ab-8 (clone DO-7 mouse monoclonal antibody; Varmdo, Sweden).
The collected data were organized, tabulated, and statistically analyzed using SPSS version 19 (SPSS Inc, Chicago, USA).
| Results|| |
This study included 40 participants distributed into three groups.
- Group I included 15 UC patients without dysplasia (10 male patients and five female patients, with mean age of 40.8 ± 15.5).
- Group II included 15 UC patients with dysplasia (eight male patients and seven female patients, with mean age of 40.2 ± 17.2).
- Group III (control) included 10 age-matched healthy individuals (six male individuals and four female individuals, with mean age of 40.3 ± 15.2). The demographic and clinical data are shown in [Table 1].
Colonoscopic examination showed significant difference between the three studied groups, according to an endoscopic scoring system for UC (Pineton et al., 2010) (P = 0.01; [Table 2]).
|Table 2: Endoscopic scoring system for ulcerative colitis among the studied groups|
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There was no significant difference between the three groups as regard COX-2 expression cox-2 in the epithelium, whereas the control group showed significantly decreased in COX-2 expression in lamina propria in comparison to the other two groups (P > 0.05), and there was a significant difference in the P53 gene expression between the studied groups (P > 0.05; [Table 3]).
|Table 3: Comparison of mean cyclooxygenase-2 in the epithelium and lamina propria and mean p53 of patients in the studied groups|
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As shown in [Table 4], there was a significant negative relationship (r > 0.5) between P53 and index of severity by colonoscopy and a significant positive relationship between P53 and duration of illness in years.
|Table 4 Correlation between colonoscopy index of severity, duration of disease, p53, and cyclooxygenase-2|
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As regard cox-2 expression in the epithelium, there was a nonsignificant weak positive relationship (r = 0.1) with index of severity by colonoscopy and a nonsignificant weak negative relationship with duration of illness (r = −0.009).
However, there was a nonsignificant weak negative relationship between cox-2 in the lamina propria and index of severity by colonoscopy (r > 0.5).
| Discussion|| |
UC is a chronic disease characterized by diffuse mucosal inflammation limited to the colon. It involves the rectum and may extend proximally in a symmetrical, circumferential, and interrupted pattern, involving parts of or entire large intestine  . Chronic inflammation in UC results in re-epithelialization of the cells and cell turnover in the colonic mucosa and leads to increased risk of errors in the cycle repair and genomic instability  . The overall incidence of CRC among UC patients is 3.7% and is 4.5% in patients with pancolitis  . The inflammatory cells in UC generate oxygen radicals and nitrogen species that lead to oxidative stress and genetic alterations involved in cell repair, leading to dysplasia and hence CRC  . All patients with UC should undergo surveillance colonoscopy every 1-3 years, starting 7-10 years after the disease onset  . Random biopsies (quadrant biopsies every 10 cm) and targeted biopsies of any visible lesion should be performed if white light endoscopy is used  . Dysplasia is a useful prognostic marker for subsequent cancer development in UC but has its limitations; hence, a combination of enhanced colonoscopic surveillance using genetic markers that are more sensitive for the detection of dysplasia might be the optimal way to manage the increased CRC risk in these patients  . The aim of this study was to try to understand the mechanism by which UC turns into dysplasia and subsequently CRC and also to detect some markers alterations that help in early detection of dysplasia and CRC. In this study, there was no significant difference between the studied groups with respect to age and sex, and this was supported by a Japanese study conducted by Watanabe et al.  and another study conducted by Sanchez et al.  who concluded that demographic data are nonsignificant variables in UC-related dysplasia. In this study, there were no significant differences between the studied groups with respect to the clinical characteristics, but the results were significant with respect to the number of motions per day and presence of mucous and blood in stool specimens, which may be explained by a direct relationship between the clinical severity and the degree of inflammation and subsequently carcinogenesis  . With respect to colonoscopic severity index, there were significant differences between UC patients with dysplasia and those patients without dysplasia, indicating a direct correlation between the index of colonoscopic severity and degree of UC-associated dysplasia. These findings were in agreement with the results of the study conducted by Kiran et al.  , who concluded that most UC-related CRC can be diagnosed or suspected on the basis of endoscopic findings and biopsy of the areas of colitis. UC-associated colorectal carcinogenesis is believed to follow a multistep process including inflammation, epithelial regeneration, hyperplastic epithelium, flat dysplasia, and finally invasive adenocarcinoma  . Aberrant activation of the arachidonic acid metabolic pathways has also been shown to be important in UC-associated colorectal carcinogenesis. Previous data have demonstrated elevated cox-2 protein and messenger RNA expression in inflamed mucosa, dysplastic lesions, and carcinomas arising in UC. Cox-2 activates procarcinogens, promotes angiogenesis, and indirectly increases free radicals production  . In this study, we analyzed the expression of both cox-2 enzyme and P53 gene in UC-related dysplasia and compared the results with a group of UC patients without dysplasia and the control group. In our study, the expression of cox-2, especially in the lamina propria, was significantly different in the UC with dysplasia group compared with the UC without dysplasia group and the control group. Cox-2 immunostaining, according to our study, was intense in patients with dysplasia and the intensity was directly correlated with the degree of dysplasia. This was supported by the study conducted by Svec et al.  , who concluded that cox-2 was significantly increased during neoplastic transformation of UC patients' colonic mucosa. In agreement with these were the results found by Shaker et al.  , who concluded that cox-2 may play a role in the pathophysiological process of inflammatory bowel disease and in the development of carcinoma. Thus, it can be used as a marker for premalignant and malignant lesions. In addition, cox-2 inhibitors can be used in the targeted therapy of these lesions. Fratila and Ilias  found that cox-2 immunostaining was positive in UC-related dysplasia patients and negative in nondysplastic patients. Our results were also supported by the study conducted by Ogino et al.  , who concluded that cox-2 overexpression is associated with worse survival among colon cancer patients, and the effect of cox-2 on clinical outcome may be modified by the P53 status. Considerable experimental evidence supports the role of cox-2 in colorectal carcinogenesis  . P53 and cox-2 were selected to grade and detect dysplasia in patients with UC, not only because there are very few studies on these lines but also because these markers have a direct evidence of genotypic alteration, which might direct the cell to become neoplastic. P53 comes into action when DNA is damaged and arrests the cell cycle so as to allow the repair. In case the repair fails, P53 directs the cell to apoptosis. Hence, P53 mutation leads to uncontrolled proliferation of cells, as the programmed cell death function is lost  . With respect to the P53 gene, our study showed that there was a significant difference in the expression of P53 gene in the UC-related dysplasia group than in the UC group without dysplasia and the control group. This result was supported by Kulaylat et al.  , who studied the difference between sporadic CRC and UC-related CRC with respect to histologic abnormalities and genetic alterations, and of their conclusions was the early expression of P53 in UC-related CRC and its late expression in sporadic CRC. There was also a study conducted by Vaji et al.  , who concluded that genetic polymorphism in P53 is closely related to UC and subsequently dysplasia. In agreement with our results are the results of the study conducted by Risques et al.  , who concluded that the expression of P53 was low in nondysplastic biopsies but progressively increased in low-grade dysplasia and high-grade dysplasia. In disagreement with our results was the study conducted by Zivkovic et al.  , who concluded that most P53 studies in UC showed an increase in the frequency of immunohistochemical overexpression and point mutation with the severity of dysplasia. This suggests that it is probably a late event unlike our results, which suggested that overexpression of P53 is an early event in UC-associated dysplasia and was expressed in low-grade dysplasia and progressively increased in high-grade dysplasia.
In contrast to our results was P53 overexpression in nondysplastic mucosa, which has been reported in at least two previous studies , . We found a positive correlation between cox-2 overexpression in the lamina propria and P53 overexpression in a group of UC-related dysplasia compared with the other two groups. In addition, there was a positive correlation between expression of cox-2 and P53 and duration of disease, severity of disease, and grade of dysplasia. This can be explained by the long duration of UC denoting long and severe exposure to inflammation, which may lead to overexpression of cox-2 as shown in previous studies conducted by Shaker and colleagues , , and the correlation with P53 alteration and the grade of dysplasia may be the mechanism by which chronic inflammation leads to overexpression of cox-2, which in turn leads to oxidative stress and P53 alteration and then dysplasia and CRC. Addition of these immunohistochemical markers to routine histologic assessment may improve the accuracy of early detection of the precancerous stages in long-standing UC patients. These markers not only discriminate early dysplasia from UC, but also correlate directly with the progression of UC from inflammation to dysplasia and carcinogenesis.
Hence, we concluded that cox-2 and P53 can be used for early detection of dysplasia and to monitor the progression of UC to carcinogenesis. COX inhibitors may be used in prophylaxis therapy for UC carcinogenesis.
Further study should be conducted to evaluate Cox-2 and P53 expression in UC-related CRC to explore mechanisms and possible prophylaxis therapy for UC carcinogenesis.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]