p27, cyclin E, and CDK2 expression in normal and cancerous endometrium

Study of the Association of Phosphatase and Tensin Homolog and p27 Expressions in Endometrial Hyperplasia and Carcinoma

Introduction:

Phosphatase and tensin homolog (PTEN) and p27 are commonly mutated gene in endometrial carcinoma (EC) and their association in development of EC has not been fully understood.

The Aim of the Study:

The aim is to clarify the association of PTEN and p27 in EC and their correlation with the histologic grade.

Material and Methods:

Paraffin-embedded 20 and 50 specimens representing EH and EC were collected, cut into 4 mm thick and stained with H&E stain for histopathological examination. All EC cases were graded according to the percentage of nonsquamous solid pattern into 3 grades. Immunohistochemical (IHC) analyses were done using a rabbit polyclonal anti-PTEN antibody and a rabbit monoclonal anti-p27 antibody. Evaluation of reactivity was categorized: 1+ (weak) = less than 10%, 2+ (moderate) = 11 to 50% and 3+ (strong) = more than 50% tumor. t-test, one way ANOVA and chi-square test were used in the statistical analysis.

Results:

Loss of PTEN was seen in 7/20 (35%) and 29/50 (58%) of EH and EC cases with significance (P =0.01824), opposite to 17/20 (85%) and 25/50 (50%) of p27 (P = 0.00334). Both antibodies showed significance in EH cases only (P = 0.00019). No correlation with the histological grade for both antibodies. Four major categories were formulated; PTEN+/p27+ (n = 2, 14, 10%, 28%), PTEN+/p27- (n = 5, 7; 25% and 14%), PTEN-/p27+ (n = 1, 11; 5%, 22%) PTEN-/p27- (n = 12, 18; 60%, 36%) cases of EH and EC, respectively with no significant difference obtained.

Conclusion:

Not all cases of PTEN negative EC showing p27 loss and vice versa. Despite many studies reacted with PTEN and p27 expression in EC, none of them is confirmatory to adjust the correlation between them in EC. So, more studies must be done to correlate between the degree of PTEN loss and p27 comprising all subtypes and grading of EC.

KDM4B and KDM4A promote endometrial cancer progression by regulating androgen receptor, c-myc, and p27kip1

Epidemiological evidence suggests that elevated androgen levels and genetic variation related to the androgen receptor (AR) increase the risk of endometrial cancer (EC). However, the role of AR in EC is poorly understood. We report that two members of the histone demethylase KDM4 family act as major regulators of AR transcriptional activityin EC. In the MFE-296 cell line, KDM4B and AR upregulate c-myc expression, while in AN3CA cells KDM4A and AR downregulate p27kip1. Additionally, KDM4B expression is positively correlated with AR expression in EC cell lines with high baseline AR expression, while KDM4A and AR expression are positively correlated in low-AR cell lines. In clinical specimens, both KDM4B and KDM4A expression are significantly higher in EC tissues than that in normal endometrium. Finally, patients with alterations in AR, KDM4B, KDM4A, and c-myc have poor overall and disease-free survival rates. Together, these findings demonstrate that KDM4B and KDM4A promote EC progression by regulating AR activity.

Direct role of adiponectin and adiponectin receptors in endometrial cancer: in vitro and ex vivo studies in humans

Low adiponectin levels are an independent risk factor for and mediate the effect of obesity on endometrial cancer in epidemiology studies. The direct or indirect mechanisms underlying these findings remain to be elucidated. We first examined the expression of adiponectin receptor 1 (AdipoR1) and 2 (AdipoR2) in normal human endometrium and in endometrial cancer tissues ex vivo. We then used KLE and RL95-2 human endometrial cancer cell lines in vitro to study relative expression of AdipoRs, to investigate the effect of adiponectin on activating intracellular signaling pathways, and to assess its potential to alter malignant properties. We report for the first time that the relative expression level of AdipoR1 is higher than AdipoR2 in human endometrial cancer tissue, but the expression of AdipoRs is not statistically different from nonneoplastic tissues. We also show for the first time in endometrial cancer cell lines in vitro that adiponectin suppresses endometrial cancer proliferation acting through AdipoRs. Adiponectin also increases the expression of the adaptor molecule LKB1, which is required for adiponectin-mediated activation of AMPK/S6 axis and modulation of cell proliferation, colony formation, adhesion, and invasion of KLE and RL95-2 cell lines. These novel mechanistic studies provide for the first time in vitro and ex vivo evidence for a causal role of adiponectin in endometrial cancer.

Involvement of Akt, Ras and cell cycle regulators in the potential development of endometrial hyperplasia in women with polycystic ovarian syndrome

OBJECTIVE

To examine whether the abundance, localization, and/or activity of cell cycle regulators CDK2, Cyclin E, p27, and survival proteins AKT and Ras in PCOS-associated endometria (with and without hyperplasia) differ from non-PCOS endometria.

METHODS

The expression of CDK2, Cyclin E, p27, AKT and Ras was measured by immunohistochemistry and/or Western blot in 9 normal endometria (NE), 12 endometria from PCOS patients without endometrial hyperplasia (PCOSE), 7 endometria from PCOS women with endometrial hyperplasia (HPCOSE), and 9 endometria from patients with endometrial hyperplasia (HE). The activity of CDK2 was assessed by an in vitro kinase assay.

RESULTS

CDK2, Cyclin E and p27 proteins were expressed mainly in the endometrial epithelial cells of the studied groups. No change in the activity of CDK2 was observed in total extracts obtained from the tissue samples. However, the nuclear expression of CDK2 in epithelial cells was slightly elevated in PCOSE and significantly increased in HPCOSE when compared to NE. Higher expression of p27 was detected in the cytoplasm of epithelial cells of PCOSE and HPCOSE when compared to NE. Also, we found an increment in Ser473-AKT phosphorylation and an over-expression of the Ras oncogene in endometria of patients with PCOS.

CONCLUSION

The PCOS condition is associated with increased Ser473-AKT phosphorylation, elevated expression of Ras, increased cytoplasmic abundance of p27, and increased nuclear abundance of CDK2 in the endometrial epithelial cells. These biological events could potentially provide a chance for endometrial cells from PCOS patients to exit the controlled cell cycle and become hyperplastic at a later stage.

Transforming growth factor-beta, estrogen, and progesterone converge on the regulation of p27Kip1 in the normal and malignant endometrium

Hormones and growth factors regulate endometrial cell growth. Disrupted transforming growth factor-beta (TGF-beta) signaling in primary endometrial carcinoma (ECA) cells leads to loss of TGF-beta-mediated growth inhibition, which we show herein results in lack of up-regulation of the cyclin-dependent kinase inhibitor p27(Kip1) (p27) to arrest cells in G(1) phase of the cell cycle. Conversely, in normal primary endometrial epithelial cells (EECs), TGF-beta induces a dose-dependent increase in p27 protein, with a total 3.6-fold maximal increase at 100 pmol/L TGF-beta, which was 2-fold higher in the nuclear fraction; mRNA levels were unaffected. In addition, ECA tissue lysates show a high rate of ubiquitin-mediated degradation of p27 compared with normal secretory-phase endometrial tissue (SE) such that 4% and 89% of recombinant p27 added to the lysates remains after 3 and 20 h, respectively. These results are reflected in vivo as ECA tissue lacks p27 compared with high expression of p27 in SE (P < or = 0.001). Furthermore, we show that estrogen treatment of EECs causes mitogen-activated protein kinase-driven proteasomal degradation of p27 whereas progesterone induces a marked increase in p27 in both normal EECs and ECA cells. Therefore, these data suggest that TGF-beta induces accumulation of p27 for normal growth regulation of EECs. However, in ECA, in addition to enhanced proteasomal degradation of p27, TGF-beta cannot induce p27 levels due to dysregulated TGF-beta signaling, thereby causing 17beta-estradiol-driven p27 degradation to proceed unchecked for cell cycle progression. Thus, p27 may be a central target for growth regulation of normal endometrium and in the pathogenesis of ECA.

Expression of cell cycle regulator p57kip2, cyclinE protein and proliferating cell nuclear antigen in human pancreatic cancer: An immunohistochemical study

AIM: To investigate the effects of p57^kip2, cyclinE protein and proliferating cell nuclear antigen (PCNA) on occurrence and progression of human pancreatic cancer.

METHODS: The expression of p57^kip2, cyclinE protein and PCNA in tumor tissues and adjacent tissues from 32 patients with pancreatic cancer was detected by SP immunohistochemical technique.

RESULTS: The positive expression rate of p57^kip2 protein in tumor tissues was 46.9%, which was lower than that in adjacent pancreatic tissues (χ² = 5.317, P<0.05). p57^kip2 protein positive expression remarkably correlated with tumor cell differentiation (P<0.05), but not with lymph node metastasis (P>0.05). The positive expression rate of cyclinE protein in tumor tissues was 68.8%, which was higher than that in adjacent pancreatic tissues (χ² = 4.063, P<0.05). CyclinE protein positive expression significantly correlated with tumor cell differentiation and lymph node metastasis (P<0.05). The positive expression rate of PCNA in the tumor tissues was 71.9%, which was higher than that in adjacent pancreatic tissues (χ² = 5.189, P<0.05). PCNA positive expression remarkably correlated with tumor cell differentiation and lymph node metastasis (P<0.05).

CONCLUSION: The decreased expression of p57^kip2 and/or overexpression of cyclinE protein and PCNA may contribute to the occurrence and progression of pancreatic cancer. p57^kip2, cyclinE protein, and PCNA play an important role in occurrence and progression of pancreatic cancer.

Significantly decreased P27 expression in endometrial carcinoma compared to complex hyperplasia with atypia (correlation with p53 expression)

P27 expression was examined on paraffin-embedded specimens in proliferative, secretory, hyperplastic and neoplastic human endometrium by immunohistochemistry. The results of p27 immunoreactivity in endometrial carcinomas were compared with clinicopathological indicators as well as with p53 expression. Thirty-eight cases of endometrial carcinoma, 30 normal functional (15 proliferative, 15 secretory), 24 hyperplastic endometrium (12 without atypia, 12 with atypia) specimens were studied by using monoclonal p27 and p53 antibodies. The streptavidin-biotin-peroxidase detection system was used and the intensity and the distribution of immunoreactivity was evaluated semiquantitatively. p27 expression was present both in the proliferative and secretory phases; the expression being stronger in the secretory period. In complex hyperplasia with atypia, p27 expression was even higher and it was significantly reduced in the endometrial carcinoma group (p<0.05). No significant correlation was found between p27 expression and any of the clinicopathologic prognostic parameters (p>0.05). Nuclear p53 expression was detected in 13 (34.2%) patients with endometrial carcinoma and was higher in non-endometrioid carcinomas and in tumors with increasing FIGO grade (p<0.05). High expression of p53 was not found to be a significant prognostic indicator of survival (p>0.05). No p53 expression was detected in the endometria with proliferation, secretion or hyperplasia either simple without atypia or complex with atypia. Surprisingly, tumors with absent/low p27 expression showed absent/low p53 expression. Our data suggest that p27 is necessary to control the proliferation of endometrium and its loss of expression seems to play a role in some aspects of endometrial carcinogenesis.