| Abstract|| |
Context: Prostate cancer is the most common malignant tumor in men. Tumor grade is one of the most important prognostic factors of prostate cancer. P53 and Ki-67 expressions have also been considered to be prognostic factors. Aims: This study was performed to investigate the frequency of these proteins expression and compare the obtained results with Gleason's grading. Settings and Design: In this cross-sectional study, 49 paraffin blocks of prostate cancers were assessed. Tumor grade was determined according to the Gleason's criteria. Materials and Methods: Ki-67 and P53 expressions were determined by immunohistochemical staining. Statistical Analysis: The obtained results were analyzed and evaluated using Spearman's statistical test (SPSS version 15). Results: Three out of 49 (6.1%) cases were well differentiated, 21 (43%) moderately differentiated and 25 (51%) were poorly differentiated. P53 was negative in all well-differentiated cases. Ki-67 was negative in 14 cases (28%) including all well-differentiated tumors. Among moderately and poorly differentiated tumors Ki-67 was negative in eight (38%) and three (12%) of cases, respectively. A statistically significant relation was observed between the increased Ki-67 labeling index (LI) and increased Gleason's grade. Conversely, no statistically significant relation was found between P53 expression and increased Gleason's grade. Conclusions: According to the findings of this study, it seems that Ki-67 can be used as a prognostic factor for prostate cancer. On the other hand, the probable relation between P-53 and prostate cancer prognosis requires further studies.
Keywords: Gleason′s grading, Ki-67 (MIB-1), P53, prostate cancer
|How to cite this article:|
Madani SH, Ameli S, Khazaei S, Kanani M, Izadi B. Frequency of Ki-67 (MIB-1) and P53 expressions among patients with prostate cancer. Indian J Pathol Microbiol 2011;54:688-91
|How to cite this URL:|
Madani SH, Ameli S, Khazaei S, Kanani M, Izadi B. Frequency of Ki-67 (MIB-1) and P53 expressions among patients with prostate cancer. Indian J Pathol Microbiol [serial online] 2011 [cited 2020 Sep 18];54:688-91. Available from: http://www.ijpmonline.org/text.asp?2011/54/4/688/91492
| Introduction|| |
Prostate cancer is the most common malignant tumor in men and also the second cause of death among malignant tumors in western countries. The etiology of prostate cancer is unknown but clinical and experimental observations suggest that hormonal, genetic, and environmental factors influence its pathogenesis. Specific molecular mechanisms are involved in the development and progression of prostate cancer. More than 95% of prostate cancers are adenocarcinoma. 
Nowadays, more patients are diagnosed at earlier stages. Increased detection of the disease can be due to increased availability of prostatic-specific antigen (PSA) measurement and also because of using other diagnostic methods. With delay in early diagnosis of the low-grade tumor, the quality or length of patient's life is not significantly changed, but a high-grade tumor in a young person might spread quickly and lead to the patient's death within 2 years. Despite high incidence of this cancer, lack of biological information in this field results in a lot of disagreements about the early steps of its clinical assessment and screening in the society. 
Prognostic factors are divided into two clinical and biological groups. Clinical factors are obtained using blood tests and radiological and microscopic evaluation of biopsies. Tumor grading is one of these important factors. Several grading systems have been introduced for prostate cancer. One of these methods, which is very acceptable, is Gleason's grading. This method is based on the patterns of tumor cell differentiation. Range of grading is from one to five. Total Gleason's grading (score) is obtained by sum of total grades of primary and secondary patterns together. Therefore, Gleason's grading will vary from 2 to 10. Gleason's grade is 2-4 in well-differentiated tumors, 5-7 in moderately differentiated tumors, and 8-10 in poorly differentiated tumors. Regarding Gleason's grading, probability of patients' mortality is determined.  Biological factors are other categories of prognostic factors. Among these P53, P27, and Ki-67 can be noted. In some studies, the incidence of P53 has been associated with higher grades of tumors and worse prognosis of the diseases.  Although another study showed different results, nuclear staining for P53 was positive at least in the aggregates of tumoral cells.  Ki-67 is a type of cellular protein that is found during duplication. In fact, Ki-67 is one of the cell cycle regulator proteins. Ki-67 index was higher in carcinoma than hyperplasia and higher in metastatic than nonmetastatic cases. Additionally, Ki-67 index is determined by immunohistochemical (IHC) techniques and an increased Ki-67 index may indicate a poor prognosis of disease. ,,, Considering the proven correlation between Gleason;s grading and prognosis of prostate cancer, along with proposing of P53 (a tumor suppressor protein) and Ki-67 (MIB-1) as prognostic factors; this study was performed to investigate the freguency of these markers expressions in prostate cancer and their probable relation with Gleason's grading.
| Materials and Methods|| |
In this cross-sectional study, paraffin blocks of prostate cancer biopsies of 49 patients diagnosed between 2005 and 2007 were used. Recuts were prepared and were stained by hematoxylin-eosin method. The slides were examined and the tumor's grade was determined by using Gleason's grading system. Thereafter, appropriate sections were prepared for IHC staining and slides were stained forP53 and Ki-67 markers. The results were evaluated blindly by another pathologist. Each slide was evaluated at ×40 magnification in order to find areas with maximum positive cells. Then these areas were examined at ×400 magnification and the percentage of positive cells to total cells was calculated. In this study, at least 500 cells were counted and only the cells that were definitely positive for the desired marker were considered. P53 was reported as positive or negative, whereas in case of Ki-67 the tumors were divided into five groups regarding the percentage of positive cells. Cases in which the percentage of stained cells was less than or equal to 2% were considered negative. Cases with Ki-67 index of less than or equal to25% were considered 1+, 26-50% as 2+, 51-75% as 3+ and 76-100% as 4+.  The results were analyzed and evaluated with SPSS software version 15. For statistical analysis of Gleason's grading Spearman's statistical test was used.
| Results|| |
Forty-nine cases in total were investigated. The mean age of patients was about 74.5 ± 8.3 years, with a range of 48 to 94 years.
Categorizing patients according to combined Gleason's grading, three patients (6.1%) were graded 4, three others (6.1%) were graded 5, eight(16.3%) were graded 6,ten (20.4%) were graded 7, eleven (22.4%) were graded 8, seven (14.3%) were graded 9 and seven (14.3%) were graded 10. Based on tumor differentiation, three (6.1%) cases were reported as well-differentiated, 21 (42.9%) as moderately differentiated and 25 (51%) as poorly differentiated [Figure 1].
|Figure 1: Prostatic carcinoma with the combined Gleason's grade 10 of 10 (hematoxylin and eosin, ×400)|
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In IHC staining for P53, 28 cases (57.1%) were reported as negative and 21(42.9%) cases as positive. Nine cases (42.8%) of moderately differentiated tumors and 12 cases (48%) of poorly differentiated tumors were positive for P53. On the other hand 12 cases with moderate differentiation (57.1%), 13 cases with poor differentiation (52%) and 3 cases with well differentiation (100%) were negative for P53 [Table 1].
|Table 1: Frequency of positive and negative P53 immunostaining in relation to differentiation and Gleason's grade|
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As a result, no significant correlation was found between positive cases of P53 and increased Gleason's grading in the present study [Figure 2].
|Figure 2: P53 staining in prostatic carcinoma with the combined Gleason's grade 10 of 10 (IHC, ×400)|
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In Ki-67 stained samples, 14 cases (28.6%) were negative (index <2%), of which three, eight, and three case were poorly, moderately, and well differentiated, respectively. Twenty-four cases (49%) were reported as 1+ with equal frequency in both poorly and moderately-differentiated tumors. Six cases (12.2%) as 2+, of which five and one were poorly and moderately- differentiated, respectively. Two cases (4.1%) were 3+ belonging to poorly differentiated group and three cases (6.1%) were 4+ also three belonging to a poorly differentiated group. In cases of well-differentiated tumors, all were negative for Ki-67. Of 21 cases of moderately differentiated tumors, eight cases (38%) were negative, while 12 cases (58%) were indexed as 1+ and one case (5%) as 2+ [Figure 3].
|Figure 3: Ki-67 staining in prostatic carcinoma with the combined Gleason's grade 10 of 10 (IHC, ×100)|
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Concerning Ki-67 index in poorly differentiated tumors, three cases (12%) were negative, whereas 12 cases (48%) were 1+, five cases (20%) 2+, two cases (8%) 3+, and three cases (12%) 4+ [Table 2]. Consequently, a statistically significant correlation was observed between Ki-67 positivity and increased Gleason's grade (Spearman correlation test) (P=0.001).
|Table 2: Frequency of the Ki-67 labeling index in relation to differentiation and Gleason´s grade|
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| Discussion|| |
In 49 studied tumors, P53 marker that indicates the presence of abnormal protein of P53 was positive in 21 cases (42.9%). However, no statistically significant correlation was found between P53 positivity and increased Gleason's grades. This observation can be justified by the fact that not all cases of P53 positive patients are detected by IHC staining methods. Indeed, formalin fixation reduces expression of P53. The level of P53 experossin in our study is in accordance with many other studies. P53 mutation has been evaluated by molecular methods in another study, and 20 of 48 cases (42%) were reported to have mutant P53. 
Borce et al. showed that the accumulation of P53 had a special correlation with patients' survival in the studied population. The presence and activity of P53 was greatly associated with the cell proliferation marker (MIB-1) and the level of P53 activity was an important independent prognostic factor that was inversely associated with patient survival. Sasor et al. showed that there is nosignificant difference between the presence of P53 in low- and high-grade tumors. There was only a positive relationship between the expressions of Ki-67 and P53 in patients with low-grade prostate cancer.  The fact that no significant correlation was found between patients' P53 positivity and their Gleason's grading can be justified by low probability of detection of this marker by the IHC method. Many studies have shown that P53 is positive in prostate cancer and negative in other prostate pathologies, such as benign prostate hyperplasia, Adenosis, and even PIN. 
Ki-67 marker was positive in 35 out of 49 tumors in current study (71.4%). Theodoropoulos  showed a significant relationship between Ki-67 index and Gleason's grading of tumors with low- to high-grade differentiation. Nilson et al. showed a significant correlation between positive cases of Ki-67 and also tumoral cell differentiation. All poorly differentiated tumors, fewer than half of the moderately differentiated tumors and only one of well-differentiated tumors were positive for Ki-67 in this study. In addition, all cases of hyperplasia (BPH) were negative for Ki-67.  The results of our study are consistent with the above-mentioned studies. This study also showed that the incidence of Ki-67 expression might strongly indicate prostate cancer. Ki-67 was not confined to the basal-cell layer in all positive studied cases. Luminal cells (channel) were also positive in some cases. However, in cases of benign hyperplasia less than 2% of cells were shown to be positive for Ki-67 marker.  The present study also showed a statistically significant correlation between the Ki-67 marker and increased Gleason's grading with increased number of stained cells (P=0.001).
| Conclusion|| |
Considering that most cases of prostate cancer are diagnosed microscopically before metastatic spread and among these, few cases have rapid and life-threatening outcome. Therefore, if these groups can be differentiated from each other we can help patients remarkably.  In the current study, Ki-67 marker was shown to have a strong relationship with Gleason's grading, which has an important relationship with the prognosis of prostate cancer. Therefore, we propose that this marker can be applied along with other prostate cancer prognostic factors. Besides, P53 marker can be used in the diagnosis of malignant neoplastic proliferation.
| Acknowledgment|| |
The authors of this paper would like to thank all members of the Molecular Pathology Research Center. This paper obtained from the research project No. 87043 KUMS.
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Molecular Pathology Research Center, Emam Reza Hospital, Zakaria Razi Bol, Kermanshah
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]