|Year : 2016 | Volume
| Issue : 1 | Page : 359-363
Expression of COX-2 and p53 in juvenile polyposis coli and its correlation with adenomatous changes
Shatavisha Das Gupta1, Ram Narayan Das1, Ranajoy Ghosh1, Anway Sen1, Uttara Chatterjee1, Kaushik Saha2, Chhanda Datta1, Prafulla Kumar Mishra3, Ranjana Bandyopadhyay1
1 Department of Pathology, The Institute of Post-Graduate Medical Education and Research, Kolkata, West Bengal, India
2 Department of Pediatric Surgery, Nil Ratan Sircar Medical College and Hospital, Kolkata, West Bengal, India
3 Department of Paediatric Surgery, The Institute of Post-Graduate Medical Education and Research, Kolkata, West Bengal, India
|Date of Web Publication||13-Apr-2016|
Department of Pathology, The Institute of Post.Graduate Medical Education and Research, Kolkata - 700 001
Source of Support: None, Conflict of Interest: None
Introduction: Gastrointestinal polyps commonly affect the pediatric population. The commoner variety amongst these is the solitary rectal polyp. Juvenile polyposis coli (JPC) is rare, characterized by multiple polyps occurring throughout the gut.
Aim: The role of cyclooxygenase-2 (COX-2) has been implicated in gastrointestinal tumorigenesis. We aimed to look at the clinicopathological spectrum of solitary vs juvenile polyposis and compare their differences in expression of COX-2 and p53.
Materials and Methods: We studied 38 polyps from eight cases of JPC, collected over the past 10 years along with 40 solitary rectal polyps (SRP).
Results: The size of polyps was significantly more in cases of JPC compared to SRP. Adenomatous change was observed significantly more often in JPC. COX-2 expression was also significantly higher in the JPC group compared to SRPs. All cases of JPC polyps with adenomatous change showed strong COX-2 expression. There was no significant difference in expression of p53 in the JPC and SRP groups.
Conclusion: We observed significantly higher COX-2 expression in JPC. Establishment of the role of COX-2 in JPC will help us formulate chemopreventive therapies as an adjunct to its surgical management.
Keywords: Cyclooxygenase-2, juvenile polyposis coli, solitary rectal polyps
|How to cite this article:|
Gupta SD, Das RN, Ghosh R, Sen A, Chatterjee U, Saha K, Datta C, Mishra PK, Bandyopadhyay R. Expression of COX-2 and p53 in juvenile polyposis coli and its correlation with adenomatous changes. J Can Res Ther 2016;12:359-63
|How to cite this URL:|
Gupta SD, Das RN, Ghosh R, Sen A, Chatterjee U, Saha K, Datta C, Mishra PK, Bandyopadhyay R. Expression of COX-2 and p53 in juvenile polyposis coli and its correlation with adenomatous changes. J Can Res Ther [serial online] 2016 [cited 2019 Dec 6];12:359-63. Available from: http://www.cancerjournal.net/text.asp?2016/12/1/359/154088
| > Introduction|| |
Gastrointestinal polyps are commonly encountered in practice and form a significant proportion of pediatric surgical specimens. Amongst these, the juvenile polyps are the commonest. They are usually solitary, sporadic, and have no malignant potential. Juvenile polyposis coli (JPC), on the other hand, is a rare condition, characterized by multiple juvenile polyps occurring throughout the gut. It is often associated with adenomatous changes and a risk of development of malignancy, although the exact risk has not been fully established.
The metabolites of arachidonic acid have been studied for their role in tumorigenesis. Cyclooxygenase-2 (COX-2) is a key enzyme in the conversion of arachidonic acid to prostaglandins and affects several signal transduction pathways modulating inflammation and cell proliferation. COX-2 is found to be over expressed in familial adenomatous polyposis. Its role in JPC, however, is not yet fully established. In this study, we aim to look at the clinicopathological spectrum of solitary vs juvenile polyposis and compare their differences in expression of COX-2 and p53.
| > Materials and Methods|| |
Over the last 10 years (2004–2013), we came across eight cases of juvenile polyposis, of which six were girls and two were boys. Two girls had a positive family history. We studied 38 polyps from these eight cases for size, adenomatous changes, COX-2, and p53 expression patterns. For comparison, we chose 40 cases of solitary polyps collected over the last 1 year.
Immunohistochemistry for COX-2 was performed using rabbit monoclonal antibody to COX-2 and supersensitive polymer-based detection system (Biogenex). Formalin-fixed, paraffin-embedded tissue sections were used for staining. The tissue sections were rehydrated after deparaffinization using descending grades of alcohol and water. Antigen retrieval was done by heat treatment using microwave oven. Tris-buffered saline (TBS) was used for washing. Peroxide blocking was done for 10 min. This was followed by power block for 10 min, cleaning, and incubation with primary antibody overnight at 4°C. Slides were washed again in TBS and incubated with secondary antibody for 30 min. After washing and cleaning, link label was added and incubated for 30 min. After washing in buffer, 3,3'-diaminobenzidine (DAB) was added and incubated for 10 min. After washing, slides were counterstained with hematoxylin. Positive staining showed cytoplasmic and membrane positivity. Neutrophils in granulation tissue present on the surface served as a positive control. The grading of COX-2 expression was done semiquantitatively. Positive staining pattern was graded as: Undetected, mild (expressed in 10% tumor cells), moderate (10–50% positive tumor cells), and strong (>% positive tumor cells). For statistical analysis, undetected and mild cases were categorized as low and moderate and strong cases as high COX-2 expression., Statistical analysis was performed with two-tailed Fisher's exact test. The expression of COX-2 expression in solitary juvenile polyps and JPC cases were compared.
The staining for p53was done similarly, with prediluted commercially available antibody from BioGenex. An expression of more than 10% was taken as positive.
| > Results and Analysis|| |
In our study, we had eight JPC cases, of which two were boys and six were girls. Their ages ranged between 7 and 16 years (mean age 10.4 years, standard deviation (SD) 3.33). The patients presented with rectal bleeding, sometimes intractable, severe pallor, stunted growth, and edema. Out of the eight cases; four underwent proctocolectomy, three underwent total colectomy, and one patient had removal of polyps. The polyps varied in size from 0.5 to 5.2 cm (mean 3.6 cm, SD 1.4). The number of polyps ranged between 4 and 40 [Figure 1]. One case amongst these presented with a recurrence along the lines of anastomosis.
|Figure 1: (a and b) Photomicrograph from a case of solitary rectal polyp, showing mild adenomatous changes, under low power and higher power view (hematoxylin and eosin (H and E), ×40 and ×400, respectively). (c and d) Photomicrograph from a case of solitary rectal polyp, with mild adenomatous changes, showing low COX-2 expression, under low and high power views (COX-2, × 40 and × 400, respectively). COX = Cyclooxygenase|
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We took 40 cases of solitary rectal polyps (SRP) for comparison, in which the mean age of patients was 5.4 years (range 3–10 years, SD 1.9). The patients complained of rectal bleeding on and off. The size of SRPs was significantly lower and varied from 0.3 to 3cm in size (mean 1.42cm, SD 0.77).
The polyps were composed of dilated colonic glands, set in an inflamed and edematous stroma. The inflammatory cells consisted mainly of plasma cells with a sprinkling of eosionophils. In some cases, there was formation of mucinlakes. Lipomatous and osseous metaplasia was noted in two cases.
Adenomatous changes in the form of crowding of glands, increase in number of glands, dysplastic changes, and loss of mucin was noted more often in JPC. About 34% of cases of JPC showed adenomatous changes, with 23.4% showing mild and 10.5% showing moderate changes. Adenomatous change was noted only in 5% of SRP cases, and they showed mild changes only [Figure 2] and [Figure 3].
|Figure 2: (a and b) Colectomy specimens fromjuvenile polyposis coli (JPC) cases showing the presence of multiple polyps of sizes varying between 0.5 and 5 cm|
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|Figure 3: (a and b) Photomicrograph from a case of juvenile polyposis coli, showing moderate adenomatous changes, under low and high power view (H and E, ×40 and ×400, respectively). (c and d) Photomicrograph from a case of juvenile polyposis coli, with mild adenomatous changes, showing high COX-2 expression, under low and high power view (COX-2, ×40 and ×400, respectively)|
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COX-2 was expressed by all the cases of JPC and the level of expression was significantly higher than SRP cases (P < 0.001). The expression was strong in 65.8% of JPC polyps compared to only 7.5% of SRPs [Table 1]a. All cases of JPC polyps with adenomatous changes showed strong COX-2 expression, however, the association was weak (P < 0.8) [Table 1]b. Strong expression of COX-2 was noted in areas of SRP polyps with adenomatous changes (P < 0.001).
|Table 1b: Relationship of adenomatous changes with COX-2 expression in JPC polyps|
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JPC polyps of larger sizes (i.e., 3.7–5.2cm), maximally expressed COX-2; thereby, showing a significant association between polyp size and COX-2 expression [Table 2]. Similarly, SRP polyps also showed stronger grades of COX-2 positivity with an increase in their size.
p53 positivity was noted in 10.5% cases of JPC and 2.5% cases of SRP. The difference in expression in these two groups was not statistically significant [Table 3].
We also came across several cases of double polyps, but as they could not be classified as either JPC or SRP, they were excluded from our study. These cases also showed strong COX-2 expression.
| > Discussion|| |
The histopathological entity of juvenile polyp was first reported by Diamond in 1939 and later described in more detail by Helwig., They affect about 1% of the pediatric population. While solitary/sporadic juvenile polyps are extremely common; JPC, on the other hand, is quite rare. In JPC, polyps predominantly occur in the colorectum, varying in number from five to several hundred. In some cases, polyps can be found in the stomach, duodenum, jejunum, and ileum; although, the incidence of upper gastrointestinal tract polyps in JPC is less well-studied. Rarely, profuse gastric juvenile polyposis is found in the absence of colonic polyps.
Clinically, juvenile polyposis can present in two forms. The first is a generalized form called juvenile polyposis of infancy. Continuous deletion of BMPR1A and PTEN genes located on chromosome 10q23.2 and 10q23.3, respectively, have been implicated in its pathogenesis. These forms have a fatal course. In addition, generalized juvenile polyposis and JPC (juvenile polyps restricted to the colorectum) have been defined, which are probably variable expressions of the same disease.
A germline mutation in the SMAD4 or BMPR1 Agene is found in about 50–60% of JPC patients. Both genes are involved in the bone morphogenetic protein (BMP)/transforming growth factor (TGF)-beta signaling pathway. Most germline defects are point mutations or small base pair deletions in the coding regions ofSMAD4orBMPR1Athat can be identified by conventional sequence analysis. About 15% of the germ line genetic defects are deletions of one or more exons, or the entire SMAD4 or BMPR1A coding sequence, which can be detected by multiplex ligation-dependent probe amplification (MLPA).
JPC has been associated with increased risk of colorectal cancer. Evidence for this concept comes from a limited number of case series and collections of literature case reports, which provide variable estimates of the risk of colorectal cancer. Also other malignancies including; gastric, small bowel, and pancreatic cancer have been noted in some studies. However, a formal risk assessment of gastrointestinal cancer in patients with JP has not been reported, unlike familial adenomatous polyposis (FAP) cases. A recent cancer risk analysis study describes the relative risk and cumulative lifetime risk of development of malignancy to be around 34 and 39%, respectively. Due to its rarity, follow-up data of JPC cases are not easily available. In our setting, a large number of cases are lost to follow-up, as they switch from the pediatric to the adult sides. Another confounding factor in the risk assessment is the fact that most of the patients undergo polypectomy at a young age. So far, we do not have any established case of carcinoma developing in our JPC patients.
Unlike FAP, a far fewer numbers of polyps are required to diagnose a case as JPC. The diagnostic criteria of juvenile polyps have undergone several revisions over time. In 1999, ≥10 polyps or any juvenile polyp in a relative of an index case of JPC were required to label a case as juvenile polyposis. Jass et al., redefined it as having more than or equal to five juvenile polyps of the colorectum or having juvenile polyps throughout the gut or any number of juvenile polyps with a family history of JPC. This was modified later as presence of three to five polyps in the colorectum or juvenile polyps with a family history of JPC or occurrence of juvenile polyps throughout the gastrointestinal tract, which is currently being followed by the World Health Organization (WHO). The status of patients with two polyps, as we have often seen, is not yet fully established.
In our study, girls were found to be affected more commonly as compared to the series reported by Poddar et al. The polyps from JPC cases were found to be larger in size and presence of adenomatous changes was more commonly observed compared to SRP. Adenomatous changes are commonly associated with JPC polyps; however, its range is quite wide. It has been reported in different series to be varying between 10 and 59%.,, In our study, we found adenomatous changes in 33% of JPC cases, in keeping with the series of Wu et al. Adenomatous changes have been reported in 0–5% cases of SRP. In our setting, we found adenomatous changes in 5% of SRP cases, which is on the higher side of this range.
COX enzyme occurs in two isoforms: COX-1 and COX-2. COX-1 is constitutively expressed in many tissues including kidneys, lungs, and gastrointestinal tract; and is responsible for producing cytoprotective prostaglandins. COX-2 shares significant sequence homology and catalytic activity with COX-1. It is constitutively expressed only in placenta, macula densa of kidney, and brain. A variety of extracellular and intracellular stimuli (lipopolysaccharide (LPS), interleukin (IL) 1, tumor necrosis factor (TNF), epidermal growth factor (EGF), TGF-α, interferon (IFN)-γ, and platelet-activating factor (PAF)) can rapidly induce COX-2 at sites where it is not expressed constitutively. COX-2 is a key component of the signal transduction pathway and regulates cell proliferation. It converts arachidonic acid to prostaglandins and modulates inflammation. It plays a crucial role in gastrointestinal tumorigenesis by causing changes in cellular adhesion, local invasion, and inhibition of apoptosis. Alteration in the COX-2 expression has been observed more frequently in several types of malignant tumors because COX-2 is present independently in cells during the early stages of cell differentiation or replication., Identification of COX-2 expression is possible by immunohistochemical staining as well as messenger ribonucleic acid (mRNA) detection by reverse transcription polymerase chain reaction (RT-PCR).
Increased COX-2 expression has been demonstrated in gallbladder; high-grade squamous cell carcinoma (SCC) of esophagus; SCC and adenocarcinomas of cervix; adenomatous and metaplastic lesions of stomach; preneoplastic lesions of lung; and preinvasive neoplasias of breast, bladder, and pancreas. COX-2 positivity has been described in in situ as well as invasive SCC cervix, with invasive cancer cases showing a stronger expression.
The importance of prostaglandin pathways in colorectal carcinogenesis in FAP and the antitumor effects of nonsteroidal anti-inflammatory drugs (NSAIDs) initially emerged through in vitro and animal studies leading to the first report of sulindac inducing regression of colon polyps in four FAP patients from a single family in 1983. COX-2 over expression have also been described in inflamed and highly active mucosa of ulcerative colitis and Crohn's disease and well as ulcerative colitis associated preneoplastic and neoplastic conditions. However, data regarding its expression in JPC cases is limited. Brazowski et al., showed increased COX-2 expression with increase in degree of dysplasia in JPC. However, van Hattem et al., did not report a significant difference in COX-2 expression between dysplastic foci and nondysplastic polyp tissue. Therefore, to rule out dysplasia as a potential confounding factor, they calculated the difference in COX-2 expression in JPC versus sporadic juvenile polyps using polyp scores, rather than the overall patient scores and stratified the results by dysplasia. In doing so, the polyps containing dysplastic foci were excluded from the analysis, that is, non dysplastic JPC polyps versus sporadic juvenile polyps; and it was found that COX-2 remained significantly higher in JPC compared with sporadic juvenile polyps. We have carried out our statistical analysis similarly and JPC cases were found to strongly express COX-2, with strengths of expression increasing with size and the presence of higher grades of adenomatous changes.
The role of p53 has been extensively studied in carcinogenesis in FAP; however, no significant association has been observed between p53 expression with SRP or JPC, thereby implicating existence of different pathway of tumorigenesis. Mutations of SMAD4 or BMPR1A gene have been implicated to play more important roles in these cases.
The over expression of COX-2 in colorectal adenomas and adenocarcinomas suggests that treatment of individuals with selective COX-2 inhibitors might lower their risk of developing colorectal neoplasms. Promising preliminary studies in rodents treated with selective COX-2 inhibitors show suppression of neoplastic development with minimal toxic side effects. JPC is a condition mandating extensive bowel resections at an early age. This can be associated with significant morbidity and subject a child to the hazards of removal of large parts of the gut. Recent pharmacotherapeutic trials have led to the launch of a whole gamut of COX-2 inhibitors and each of their efficacy needs to be studied, especially in reference to JPC cases.
To sum up, we observed significantly higher expression of COX-2 in JPC compared to solitary juvenile polyps. Our findings suggest that chemoprevention with selective COX-2 inhibitors might be a useful adjunct therapy to colonoscopic polypectomy.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]