Utility of PTEN expression of endometrial "surface epithelial changes" and underlying atypical endometrial hyperplasia

Correlation of PD-L1 expression with immunohistochemically determined molecular profile in endometrial carcinomas

Endometrial carcinoma programmed death-ligand 1 (PD-L1) expression in tumor cells (TCs) and tumor-associated inflammatory cells (ICs) have recently been reported in several studies which vary in terms of their cohort size, design, and methodology. We aimed to assess PD-L1 staining in endometrial carcinomas and correlate this with clinical and pathological factors and PTEN, ARID1A, p53, and MMR protein expression. PD-L1 immunohistochemistry was performed on whole tissue sections of all tumor blocks of 59 consecutive unselected endometrial carcinomas between November 2018 and September 2019. TC and IC PD-L1 positivity with a 1% cut-off value was observed in 10.2% and 67.8% of cases, respectively, and with a 5% cut-off value in 3.4% and 42.4% of cases, respectively. TC PD-L1 positivity with both 1% and 5% cut-off values was significantly related to ARID1A loss (p = 0.001 and p = 0.046, respectively). IC PD-L1 positivity with 1% and 5% cut-off values and combined score were significantly associated with MMR protein deficiency (p = 0.041, p = 0.031, and p = 0.028, respectively). Advanced stage tumors exhibited more frequent PD-L1 expression in ICs (p = 0.039). MELF-type myometrial invasion pattern was more common in tumors with ARID1A loss (p = 0.047). We observed higher rates of IC PD-L1 positivity in endometrial carcinomas than documented in prior studies; this may be related to our usage of "recent" paraffin blocks and whole tissue sections of all tumor blocks. There was a much higher PD-L1 expression in the ICs compared to TCs in our cases. We confirm a previously documented association between MMR deficiency and PD-L1 expression and show a novel association between ARID1A loss and PD-L1 expression in endometrial carcinomas. ARID1A loss represents a potential biomarker of immune checkpoint inhibitor response in endometrial carcinoma.

Research progress on the PI3K/AKT signaling pathway in gynecological cancer (Review)

The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway is involved in the regulation of multiple cellular physiological processes by activating downstream corresponding effector molecules, which serve an important role in the cell cycle, growth and proliferation. This is a common phenomenon; overactivation of the pathway is present in human malignancies and has been implicated in cancer progression, hence one of the important approaches to the treatment of tumors is rational drug design using molecular targets in the PI3K/AKT signaling pathway. In brief, the present review analyzed the effects of the PI3K/AKT signaling pathway on certain gynecological cancer types.

PTEN expression in endometrial hyperplasia and risk of cancer: a systematic review and meta-analysis

PURPOSE

Rates of progression of endometrial hyperplasia (EH) to endometrial cancer (EC) are highly variable. Among several prognostic markers, PTEN has been recommended by ESMO-ESGO-ESTRO to identify premalignant EH. However, its prognostic accuracy is unclear. Thus, we aimed to assess: (1) the association between PTEN loss in EH and risk of cancer, and (2) the prognostic accuracy of PTEN immunohistochemistry in EH.

METHODS

Electronic databases were searched from their inception to June 2018. All studies assessing PTEN immunohistochemistry in EH and the presence of EC on subsequent hysterectomy were included. Odds ratio (OR), sensitivity, specificity, positive and negative predictive value (PPV and NPV), positive and negative likelihood ratio (LR + and LR-) and area under the curve (AUC) on SROC curves were calculated with subgroup analysis (short/long-term; atypical/non-atypical EH).

RESULTS

Nine retrospective studies assessing 933 EH were included. PTEN loss in EH was significantly associated with increased risk of EC (OR = 3.32, p = 0.001). The association was significant only on the short term ( < 1 year) (OR = 3.45, p = 0.002) and in atypical EH (OR = 1.89, p = 0.01). For overall analysis and short-term/atypical EH subgroup the prognostic accuracy was low, with sensitivity = 0.58 and 0.68, specificity = 0.60 and 0.48, VPp = 0.41 and 0.54, VPN = 0.75 and 0.63, LR +  = 1.80 and 1.37, LR - =  0.62 and 0.56, AUC = 0.687 and 0.721, respectively.

CONCLUSION

PTEN loss in EH is a risk factor for EC, but is not reliable in predicting the risk of EC. In atypical EH, PTEN loss is associated with a risk of concurrent EC of over 50%. This information might integrate the patients' informed consent for the choice of treatment (conservative/hysterectomy), especially in borderline cases. In conservative approach, PTEN loss might suggest closer follow-up.

Molecular alterations of PI3K/Akt/mTOR pathway: a therapeutic target in endometrial cancer

It is well established that the PI3K/Akt/mTOR pathway plays a central role in cell growth and proliferation. It has also been suggested that its deregulation is associated with cancer. Genetic alterations, involving components of this pathway, are often encountered in endometrial cancers. Understanding and identifying the rate-limiting steps of this pathway would be crucial for the development of novel therapies against endometrial cancer. This paper reviews alterations in the PI3K/Akt pathway, which could possibly contribute to the development of endometrial cancer. In addition, potential therapeutic targets of this pathway with emphasis on the mTOR inhibitors are also presented.

A genetic mouse model of invasive endometrial cancer driven by concurrent loss of Pten and Lkb1 Is highly responsive to mTOR inhibition

Signals from the tumor suppressors PTEN and LKB1 converge on mTOR to negatively regulate its function in cancer cells. Notably, both of these suppressors are attenuated in a significant fraction of human endometrial tumors. In this study, we generated a genetic mouse model of endometrial cancer driven by concomitant loss of these suppressors to gain pathophysiological insight into this disease. Dual loss of Pten and Lkb1 in the endometrial epithelium led to rapid development of advanced endometrioid endometrial tumors with 100% penetrance and short host survival. The tumors displayed dysregulated phosphatidylinositol 3-kinase (PI3K)/Akt and Lkb1/Ampk signaling with hyperactivation of mTOR signaling. Treatment with a dual PI3K/mTOR inhibitor, BEZ235, extended the time before tumor onset and prolonged overall survival. The PI3K inhibitor GDC-0941 used as a single agent reduced the growth rate of primary tumor implants in Pten/Lkb1-deficient mice, and the mTOR inhibitor RAD001 was unexpectedly as effective as BEZ235 in triggering tumor regression. In parallel, we also found that ectopic expression of LKB1 in PTEN/LKB1-deficient human endometrial cancer cells increased their sensitivity to PI3K inhibition. Together, our results demonstrated that Pten/Lkb1-deficient endometrial tumors rely strongly on deregulated mTOR signaling, and they provided evidence that LKB1 status may modulate the response of PTEN-deficient tumors to PI3K or mTOR inhibitors.

High frequency of PIK3R1 and PIK3R2 mutations in endometrial cancer elucidates a novel mechanism for regulation of PTEN protein stability

We demonstrate that phosphatidylinositol 3-kinase (PI3K) pathway aberrations occur in >80% of endometrioid endometrial cancers, with coordinate mutations of multiple PI3K pathway members being more common than predicted by chance. PIK3R1 (p85α) mutations occur at a higher rate in endometrial cancer than in any other tumor lineage, and PIK3R2 (p85β), not previously demonstrated to be a cancer gene, is also frequently mutated. The dominant activation event in the PI3K pathway appears to be PTEN protein loss. However, in tumors with retained PTEN protein, PI3K pathway mutations phenocopy PTEN loss, resulting in pathway activation. KRAS mutations are common in endometrioid tumors activating independent events from PI3K pathway aberrations. Multiple PIK3R1 and PIK3R2 mutations demonstrate gain of function, including disruption of a novel mechanism of pathway regulation wherein p85α dimers bind and stabilize PTEN. Taken together, the PI3K pathway represents a critical driver of endometrial cancer pathogenesis and a novel therapeutic target.

"Surface epithelial changes" in uterine endometrioid carcinoma mimicking micropapillary serous borderline tumor of ovary: report of two cases and review of the literature

We encountered two cases of endometrioid carcinoma of uterus with extensive surface epithelial changes (SECs) mimicking serous borderline tumor (SBT) of the ovary. The first case was a well-differentiated endometrioid carcinoma arising in a background of complex atypical hyperplasia. The second case was moderately-differentiated endometrioid carcinoma with squamous and mucinous differentiation. The SECs comprised of thin microapapillae without hierarchal branching, lined by cuboidal cells with eosinophilic cytoplasm and mild to moderate nuclear atypia. These areas were reminiscent of SBTs of ovary, micropapillary type. This report expands the existing spectrum of SECs. Serous borderline tumor of ovary like surface epithelial changes could be misleading if present in an endometrial biopsy or curettings. Therefore, knowledge of this morphologic variation is important.