BKCa participates in E2 inducing endometrial adenocarcinoma by activating MEK/ERK pathway

Background

The large-conductance, voltage-gated, calcium (Ca (2+))-activated potassium channel (BKCa) plays an important role in regulating Ca (2+) signaling and cell physiological function, and is aberrantly expressed in some types of cancers. The present study focuses on identifying the oncogenic potential and clinical significance of BKCa in endometrial adenocarcinoma, as well as exploring the mechanistic relevance by 17β -estradiol (E2) inducing aberrant activation of MEK1/2 and ERK1/2 via BKCa.

Methods

The expression of BKCa, ERK1/2 and p-ERK1/2 were examined by immunohistochemical staining in 263 cases, including 185 primary types I endometrial cancer tissues, 38 atypical endometrial hyperplasia tissues and 40 normal endometrium tissues. Cell growth, cycle, apoptosis rate, migration and invasion was separately tested in Ishikawa cells using siRNA-BKCa and/or E2 treatment, as well as the expression of these interested proteins by western blot analysis.

Results

We showed that expression of BKCa is significantly elevated in 185 types I endometrial adenocarcinoma tissues compared to those of the normal endometrium and atypical endometrial hyperplasia tissues. Furthermore, in vitro observations revealed that down-regulation of BKCa expression inhibited cell growth by both enhancing apoptosis and blocking G1/S transition, suppressed cell migration and invasion in Ishakiwa cells, and decreased the expression of p-MEK1/2 and p-ERK1/2. Additionally, RNAi-mediated knockdown of BKCa attenuated the increased cellular growth and invasion, as well as the elevated expression of p-MEK1/2 and p-ERK1/2 proteins, induced by E2 stimulation. More importantly, the aberrant expression of BKCa and p-ERK1/2 were closely related with poor prognostic factors in type I endometrial cancer, and up-regulated expression of p-ERK1/2 was significantly associated with shorter disease-free survival (DFS) and overall survival (OS) and was an independent prognostic factor in type I endometrial cancer patients.

Conclusion

Our results demonstrated that BKCa and the key downstream effectors p-ERK1/2 could be involved in important signaling pathways in initiation and development of endometrial adenocarcinoma and may provide a new therapeutic approach for women with endometrial cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5027-9) contains supplementary material, which is available to authorized users.

Pathology of Endometrial Carcinoma

On a clinicopathological and molecular level, two distinctive types of endometrial carcinoma, type I and type II, can be distinguished. Endometrioid carcinoma, the typical type I carcinoma, seems to develop through an estrogen-driven "adenoma carcinoma" pathway from atypical endometrial hyperplasia/endometrioid intraepithelial neoplasia (AEH/EIN). It is associated with elevated serum estrogen and high body mass index and expresses estrogen and progesterone receptors. They are mostly low grade and show a favorable prognosis. A subset progresses into high-grade carcinoma which is accompanied by loss of receptor expression and accumulation of TP53 mutations and behaves poorly. Other frequently altered genes in type I carcinomas are K-Ras, PTEN, and ß-catenin. Another frequent feature of type I carcinomas is microsatellite instability mainly caused by methylation of the MLH1 promoter. In contrast, the typical type II carcinoma, serous carcinoma, is not estrogen related since it usually occurs in a small uterus with atrophic endometrium. It is often associated with a flat putative precursor lesion called serous endometrial intraepithelial carcinoma (SEIC). The molecular pathogenesis of serous carcinoma seems to be driven by TP53 mutations, which are present in SEIC. Other molecular changes in serous carcinoma detectable by immunohistochemistry involve cyclin E and p16. Since many of the aforementioned molecular changes can be demonstrated by immunohistochemistry, they are useful ancillary diagnostic tools and may further contribute to a future molecular classification of endometrial carcinoma as recently suggested based on The Cancer Genome Atlas (TCGA) data.

Oncologic Safety of Laparoscopy in the Surgical Treatment of Type II Endometrial Cancer

Background

Laparoscopy is considered the method of choice in the operative treatment of type I endometrial carcinoma (EC). However, there is a paucity of data regarding the safety of endoscopy for type II EC because these malignancies have several biological similarities with ovarian cancer.

Objectives

This study aimed to evaluate the feasibility, operative outcomes, and oncologic safety of laparoscopic surgery in patients with type II EC.

Methods

A retrospective study with histologically confirmed serous or clear-cell EC without peritoneal carcinomatosis treated by laparoscopy (G1) or laparotomy (G2) was conducted. Procedures included hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and pelvic and para-aortic lymphadenectomy.

Results

From 2009 to 2015, 89 patients were included; 53 women underwent laparoscopy and 36 underwent laparotomy. No relevant epidemiological or oncologic difference between groups was observed. The mean number of removed pelvic nodes was 16 [±10] and 12 [±13] in group 1 (G1) and group 2 (G2), respectively (P= 0.127). The mean number of dissected para-aortic nodes was significantly greater in the laparoscopic group (11 [±9] vs 6 [±9],P= 0.006). Para-aortic metastasis was significantly more often observed in the endoscopy group (26% vs 13%,P= 0.04). Adjuvant therapies were given to 86% of the patients in the study and 75% in the control group (P= 0.157). No excessive blood loss, casualty related to surgery, intraoperative complication, or conversion to laparotomy occurred in G1. Ten (18%) women from G1 and 36% (13/36) in G2 developed relevant postoperative complications (P= 0.03). The median duration of follow-up was 38 months for the laparoscopy and 47 months for the open surgery (P= 0.12). The 5-year overall and disease-free survival were similar, 86% versus 78% and 58% versus 51% for G1 and G2, respectively (P= 0.312).

Conclusions

Laparoscopy is oncologically at least not inferior to laparotomy for the surgical treatment of type II EC. Endoscopic techniques are feasible, effective, result in significantly less morbidity, and improved quality staging. Although statistical significance was not reached, laparoscopy was associated with superior oncologic results.

Induction of Apoptosis in Endometrial Cancer (Ishikawa) Cells by Pogostemon cablin Aqueous Extract (PCAE)

Pogostemon cablin (PC) is a traditional herbal medicine used in the treatment of the common cold, nausea, diarrhea, and even for headaches and fever. However, the mechanisms underlying the anti-proliferative activity of PC in endometrial cancer (EC) cells have yet to be fully elucidated. This study investigated the anticancer effects of an aqueous extract of Pogostemon cablin (PCAE), specifically induced apoptosis in EC (Ishikawa) cells. Proliferation of EC cells following exposure to PCAE was assessed by an MTT assay. DNA content and the induction of cell cycle apoptosis were analyzed by flow cytometry (FACS Calibur). Protein caspase-3 and, -9 as well as AIF were investigated using Western blot. Our results demonstrate growth inhibition of Ishikawa cells by PCAE. Furthermore, caspase-3 activity caused PCAE-treated cell lines to accumulate in apoptosis. Gene expression profiling (GEP) results further suggest that, in addition to its known effects with regard to EC prevention, PCAE may also exert antitumor activity on established EC cells. Many previous studies have identified the chemo-preventive effects of natural plant materials and the potential role of these materials in chemotherapy. This current study used human EC Ishikawa cells to investigate the anti-tumor effects of PCAE in EC cells. Our results demonstrate that PCAE inhibits the growth of cancer cells and induces apoptosis, which suggests the potential applicability of PCAE as an antitumor agent.

Laparoscopic Sentinel Node Biopsy Using Real-time 3-dimensional Single-photon Emission Computed Tomographic Guidance in Endometrial Cancer

In endometrial cancer, the histopathological analysis of the lymphatic nodes is essential to establish a correct prognosis and tailored adjuvant treatment. It is well-known that patients with early-stage endometrial cancer have a low incidence of nodal disease. In this group, systematic lymphadenectomy is not recommended. To improve the detection rate of sentinel nodes in clinical practice, new techniques are emerging like real-time 3-dimensional single-photon emission computed tomographic (SPECT) imaging. We report our experience using this innovative technique for intraoperative detection of sentinel nodes in endometrial cancer. The real-time 3-dimensional SPECT sentinel node biopsy seems to be feasible and accurate in endometrial cancer although further studies are needed to set the precision and predictive values compared with the current differed SPECT techniques and blue dye techniques.