STUDY OF EXPRESSION OF PTEN IN ENDOMETRIUM AT A TERTIARY CARE CENTRE.

Background: To study the expression of PTEN (Phosphatase and Tensin homologue) in normal, hyperplastic and neoplastic endometrium by immunohistochemistry in normal to neoplastic endometrial lesions including endometrial carcinoma. Materials and Methods: Formalin fixed paraffin embedded (FFPE) sections of spectrum of endometrium in hundred different cases were taken from secretory phase to endometrial carcinoma and subjected to Immunohistochemistry using PTEN. Results: Immunoreactivity was taken as positive when a brown colour was noted in the nuclei or cytoplasm with intensity of staining being graded from 0 to 3+. Also if <10% of cells were positive a score of 0 was given, if 11 % to 30% cell were positive a score of 1+ , 31% to 60 % positive, a score as 2+ and > 60% positive cells a score of 3+ was given. Statistical analysis was performed with Chi-Square test and significant differences were noted between these 3 groups (p value < 0.05). Conclusion: A decreased expression of PTEN is a marker of the earliest endometrial premalignant lesions, and therefore we in our study suggest that PTEN immunostaining can be helpful in identifying premalignant conditions that are likely to progress to carcinoma. PTEN varies with phase of the menstrual cycle. It is always expressed in the estrogenic proliferative phase whereas in secretory phase its expression is variable with a post ovulatory secretory phase showing an increased PTEN expression in relation to the estrogenic proliferative phase whereas in the mid secretory phase there is loss of PTEN expression in the epithelium and an increased expression of PTEN in stroma. In the late secretory phase there is loss of PTEN expression. Stimulation of endometrium for long intervals with estrogen results in a clonal outgrowth of PTEN-depleted epithelium resulting in a pre-malignant state. 7 In around 20% of precancerous hyperplastic lesions PTEN mutations are noted.


ISSN: 2320-5407
Int. J. Adv. Res. 7 (10), 902-906 903 PTEN varies with phase of the menstrual cycle. It is always expressed in the estrogenic proliferative phase whereas in secretory phase its expression is variable with a post ovulatory secretory phase showing an increased PTEN expression in relation to the estrogenic proliferative phase whereas in the mid secretory phase there is loss of PTEN expression in the epithelium and an increased expression of PTEN in stroma. In the late secretory phase there is loss of PTEN expression. Stimulation of endometrium for long intervals with estrogen results in a clonal outgrowth of PTEN-depleted epithelium resulting in a pre-malignant state. 7 In around 20% of precancerous hyperplastic lesions PTEN mutations are noted.
Our study was conducted to see the pattern of PTEN expression in normal, hyperplastic, and neoplastic endometrium evaluate its role in the pathogenesis of preneoplastic and neoplastic lesions of the endometrium.

Materials And Methods:
The study was carried out in the Department of Pathology, Adesh Institute of Medical Sciences and Research, Bathinda over a period of two years from February 2015 to August 2017. A total of 100 cases were taken with 18 cases of proliferative phase of endometrium, 22 cases of secretory phase, 23 cases of simple hyperplasia without atypia, 15 cases of complex hyperplasia without atypia, 9 cases of complex hyperplasia with atypia and 13 cases of endometrial carcinoma.
Immunohistochemical (IHC) procedure was employed on formalin fixed paraffin embedded tissue sections to study the expression of PTEN. A mouse anti-PTEN monoclonal antibody (Biogenex, USA) was used.

Scoring system:
A brown colour in the nuclei or cytoplasm was taken as positive with intensity of staining being graded from 0 to 3+ from no staining to weak, to moderate to mark staining. Also if <10% of cells were positive a score of 0 was given, if 11 % to 30% cell were positive a score of 1+ , 31% to 60 % positive, a score as 2+ and > 60% positive cells a score of 3+ was given.

Statistical analysis:
Calculation of association using chi square test and a level ofp <0.05 was considered as statistically significant.

Results:
A total of 100 cases were considered with 18 cases of Proliferative Endometrium and 22 cases in secretory phase ( Figure 1A & B). 23 cases were found in the group Simple Hyperplasia without atypia ( Figure 1C). 15 cases were reported in the group Complex hyperplasia without atypia ( Figure 1D) and 9 cases were there in the Complex Hyperplasia with atypia group ( Figure 1E). 13 cases belonged to Endometrial Carcinoma group ( Figure 1F). The age of the patients ranged from 26-79 years with a median age being 46.73±11.55 years.

Discussion:-
Endometrial cancer is the most common malignancy of the female genital tract. The development of endometrial carcinoma is a stepwise acquisition of several genetic alterations which involves the tumour suppressor genes and the oncogenes. Estrogen and its metabolites result in DNA damage and are therefore associated with higher risk of developing endometrial cancers. 8 Loss of PTEN function results in excessive proliferation of cells which is a feature of many types of cancers, including endometrial cancers. 9,10 Hyperplasia on the other hand is a heterogenous group of lesions, which is considered by some to be reversible and truely neoplastic by some, so attempts have been made to sub classify to justify their role as a precancerous event. 11 The aim of our study was to study the expression of PTEN in normal, hyperplastic and neoplastic endometrium. The mean age of our study is in closest resemblance to the study done by Aziz et al. 12 PTEN immunoreactivity was noted in all cases of proliferative and secretory phase which was similar to study conducted by Erkanli S et al and Rao et al. 13,14 PTEN expression in simple hyperplasia without atypia was 82.60 % which is slightly lower to study by Soheila Sarmadi et al but in a study by Anuradha Rao et al PTEN expression in simple hyperplasia without atypia showed 87% positivity which correlated well with our current study. 15 In a study by Anuradha et al on the study group of hyperplasias found that simple hyperplasia without atypia had the maximum number of PTEN positive glands with the number of glands reducing as the number of complex hyperplastic glands increased, the least number of PTEN positive glands was seen in complex hyperplasia with atypia. Study conducted by Lee H et al showed the percentage of PTEN loss was significantly higher in endometrial carcinoma compared with simple hyperplasia and it was also higher in Complex atypical hyperplasia. 16 In a study by Samar A El Sheikh et al PTEN immunoreactivity was noted in all normal proliferative endometrium and all Simple hyperplasia cases whereas Complex atypical hyperplasia 66.7% showed positive immunoreactivity. The difference was highly statistically significant. 17 In a study by Tantbirojn P et al, 70 % cases of simple hyperplasia and 47 % cases of complex hyperplasia were positive. 18 In Endometrial Carcinoma, loss of PTEN expression is seen in 61.53% of cases. Orbo et al reported loss of PTEN protein expression in 55% of specimens in patients with subsequent endometrioid endometrial carcinoma. 19 In a study by Kanamori et al out of 98 advanced cases, 64 (65.3%) showed negative or mixed PTEN staining; their survival rate was significantly lower than that of PTEN positive cases. 4 In a study by Terakawa et al out of 98 advanced cases, 64 (65%) showed negative or heterogeneous PTEN staining; their survival rate was significantly lower than that of PTEN-positive cases. 20 (Table 4).

Conclusion:-
The current study showed that the loss of PTEN expression is an early event in endometrial carcinogenesis. An altered PTEN function is responsible for majority of endometrial cancers. The loss of PTEN expression is seen in the premalignant phase of the disease as well and is seen in the progression to carcinoma. Therefore a decreased PTEN expression is a marker of progression of premalignant lesions to endometrial carcinoma. It is therefore proposed that the use of PTEN immunostaining in a clinical setting will help in identifying premalignant lesions that are likely to progress to carcinoma.