Metformin Enhances Nomegestrol Acetate Suppressing Growth of Endometrial Cancer Cells and May Correlate to Downregulating mTOR Activity In Vitro and In Vivo

Antitumor progestins activity: Cytostatic effect and immune response

Progestins are used to treat some hormone-sensitive tumors. This review discusses the mechanisms of progestins' effects on tumor cells, the differences in the effects of progesterone and its analogs on different tumor types, and the influence of progestins on the antitumor immune response. Progestins cause a cytostatic effect, but at the same time they can suppress the antitumor immune response, and this can promote the proliferation and metastasis of tumor cells. Such progestins as dienogest, megestrol acetate and levonorgestrel increase the activity of NK-cells, which play a major role in the body's fight against tumor cells. The use of existing progestins and the development of new drugs with gestagenic activity may hold promise in oncotherapy.

Possible Participation of Adenine Nucleotide Translocase ANT1 in the Cytotoxic Action of Progestins, Glucocorticoids, and Diclofenac on Tumor Cells

A comparative analysis of the cytostatic effects of progestins (gestobutanoyl, megestrol acetate, amol, dienogest, and medroxyprogesterone acetate), glucocorticoids (hydrocortisone, dexamethasone), and diclofenac on tumor cells was carried out in order to confirm their in silico predicted probabilities experimentally. The results showed the different sensitivity of HeLa, MCF-7, Hep-2, K-562, and Wi-38 cell lines to progestins, glucocorticoids, and diclofenac. The minimum IC50 was found for progestin gestobutanoyl (GB) as 18 µM for HeLa cells, and varied from 31 to 38 µM for MCF-7, Hep-2, and K-562. Glucocorticoids and diclofenac were much less cytotoxic in the HeLa, MCF-7, and Hep-2 cell lines than progestins, with IC50 values in the range of 150-3000 μM. Myelogenous leukemia K-562 cells were the least sensitive to the action of progestins and glucocorticoids but the most sensitive to diclofenac, which showed a pronounced cytotoxic effect with an IC50 of 31 μM. As we have shown earlier, progestins can uniquely modulate MPTP opening via the binding of adenine nucleotide translocase. On this basis, we evaluated the expression of adenylate nucleotide translocase ANT1 (SLC25 A4) as a possible participant in cytotoxic action in these cell lines after 48 h incubation with drugs. The results showed that progestins differently regulated ANT1 expression in different cell lines. Gestobutanoyl had the opposite effect on ANT1 expression in the HeLa, K562, and Wi-38 cells compared with the other progestins. It increased the ANT1 expression more than twofold in the HeLa and K562 cells but had no influence on the Wi-38 cells. Glucocorticoids and diclofenac increased ANT1 expression in the Wi-38 cells and decreased it in the K562, MCF-7, and Hep-2 cells. The modulation of ANT1 expression discovered in our study can be a new explanation of the cytotoxic and cytoprotective effects of hormones, which can vary depending on the cell type. ANT isoforms in normal and cancerous cells could be a new target for steroid hormone and anti-inflammatory drug action.

Progestin Resistance and Corresponding Management of Abnormal Endometrial Hyperplasia and Endometrial Carcinoma

With a younger tendency in morbidity age, endometrial cancer (EC) incidence has grown year after year. Worse, even more commonly occurring is endometrial hyperplasia (EH), which is a precancerous endometrial proliferation. For young women with early EC and EH who want to preserve fertility, progestin therapy has been utilized as a routine fertility-preserving treatment approach. Nevertheless, progestin medication failure in some patients is mostly due to progestin resistance and side effects. In order to further analyze the potential mechanisms of progestin resistance in EH and EC, to provide theoretical support for effective therapeutic strategies, and to lay the groundwork for searching novel treatment approaches, this article reviews the current therapeutic effects of progestin in EH and EC, as well as the mechanisms and molecular biomarkers of progestin resistance, and systematically expounds on the potential therapeutic methods to overcome progestin resistance.

Nomegestrol acetate ameliorated adipose atrophy in a rat model of cisplatin‑induced cachexia

Cachexia, a complex disorder that results in depletion of adipose tissue and skeletal muscle, is driven by anorexia, metabolic abnormalities and inflammation. There are limited therapeutic options for this syndrome. Previous evidence has demonstrated that increasing adipose tissue may improve quality of life and survival outcomes in cachexia. Cisplatin, as a chemotherapy drug, also causes cachexia during antitumor therapy due to its adverse effects. To establish a rat model of cachexia, the animals were intraperitoneally treated with cisplatin at doses of 1, 2 and 3 mg/kg, and the rats that responded to cisplatin at the optimal dose were used to test the effect of nomegestrol acetate (NOMAc). Rats that were assessed to be sensitive to cisplatin were randomly grouped and intragastrically administered vehicle, 5 or 10 mg/kg megestrol acetate (MA) or 2.5, 5 or 10 mg/kg NOMAc. The body weights and food consumption of the rats were assessed. Serum IL-6 and TNF-α levels were assessed using ELISA. The protein expression levels of adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), peroxisome proliferator activated receptor γ (PPARγ), fatty acid synthase (FASN) and sterol regulatory element-binding protein-1 (SREBP-1) from inguinal white adipose tissue (iWAT) and epididymal white adipose tissue (eWAT) were evaluated using western blotting. The optimal way to establish a chemotherapy-induced rat model of cachexia demonstrated in the present study was to intraperitoneally administer the rats with 2 mg/kg cisplatin for 3 consecutive days. NOMAc (2.5, 5 mg/kg) and MA (10 mg/kg) were able to significantly ameliorate the loss of body weight in the cisplatin-induced cachectic rats. NOMAc significantly reduced the serum levels of TNF-α at 10 mg/kg. Morphologically, iWAT atrophy, with a remarkable reduction in adipocyte volume, was observed in the cisplatin-induced cachectic rats, but the effects were reversed by administering 5, 10 mg/kg NOMAc or 10 mg/kg MA. Furthermore, 2.5 mg/kg NOMAc markedly reduced the protein expression levels of the lipolysis genes HSL and ATGL, and 5 mg/kg NOMAc markedly enhanced the protein expression levels of adipogenesis genes, including FASN, SREBP-1 and PPARγ in iWAT but not in eWAT. NOMAc was demonstrated to improve cachexia at lower doses compared with MA. Overall, NOMAc is likely to be a promising candidate drug for ameliorating cancer cachexia induced by cisplatin.

Thyroid Hormone Receptor β Knockdown Reduces Suppression of Progestins by Activating the mTOR Pathway in Endometrial Cancer Cells

Progestin resistance is a major obstacle to conservative therapy in patients with endometrial cancer (EC) and endometrial atypical hyperplasia (EAH). However, the related inducing factor is yet unclear. In this study, thyroid hormone and its receptor α (TRα) and β (TRβ) of patients were assayed. THRB-silenced RL95-2 and KLE EC cells were cultured to investigate the response of progestins. Transcriptomics and Western blotting were performed to investigate the changes in signaling pathways. We found that THRB, rather than THRA, knockdown promoted the viability and motilities of RL95-2 cells but not KLE cells. The suppressive effect of progestins on cell growth and motility significantly decreased in THRB-silenced RL95-2 cells. Multiple proliferation-related signaling pathways were enriched, and the activities of mammalian targets of rapamycin (mTOR)/4e-binding protein 1 (4EBP1)/eukaryotic translation initiation factor 4G (eIF4G) rather than phosphorylated protein kinase B (Akt) were remarkably boosted. Progestin treatment enhanced the effects, and the augmentation was partially abated on supplementation with T3. In THRB-knockdown KLE cells, the progestins-activated partial signaling pathway expression (either mTOR or eIF4G), and supplementation with T3 did not induce noticeable alterations. The serum levels of triiodothyronine (T3) were significantly lower in patients with EC compared with healthy women. A strong expression of TRβ was observed in most patients with EC and EAH sensitive to progestin treatment. In contrast, TRα positive expression was detected in less than half of the patients sensitive to progestin therapy. In conclusion, THRB knockdown enhanced the viability and motility of type I EC cells and attenuated the suppressive effects of progestins by activating the mTOR-4EBP1/eIF4G pathway. Lower expression of THRB is likely correlated with progesterone resistance.

Outcomes of women treated with progestin and metformin for atypical endometrial hyperplasia and early endometrial cancer: a systematic review and meta-analysis

OBJECTIVE

Progestin therapy is the recommended fertility-sparing management of atypical endometrial hyperplasia or early-stage endometrial cancer in reproductive-aged women. Our objective was to evaluate disease relapse after progestin and metformin versus progestin therapy alone in patients with endometrial hyperplasia or cancer. Our secondary outcomes were disease remission, clinical pregnancy and live birth rate.

METHODS

A systematic review of the literature was conducted (MEDLINE, Web of Science, Cochrane Library, CINAHL, LILACS, clinicaltrials.gov) from inception to April 2021. Studies of reproductive-aged women with atypical endometrial hyperplasia or early endometrial cancer who received progestin and metformin or progestin alone for fertility-sparing management, were included in the review. Early endometrial cancer was defined as grade 1, stage 1 disease. Exclusion criteria included women with higher grade endometrial cancer and when conservative management was not for fertility-sparing purposes. Data are presented as odds ratios (ORs) and 95% confidence intervals (CIs) with fixed or random effects meta-analysis. Quality scoring was based on the Newcastle-Ottawa and Jadad scales.

RESULTS

In total, 271 reports were identified and six studies met the inclusion criteria. These studies included 621 women; 241 (38.8%) patients received combined therapy and 380 (61.2%) received progestin therapy alone. Relapse rates were lower for progestin and metformin than for progestin therapy alone (pooled OR 0.46, 95% CI 0.24 to 0.91, p=0.03). The remission rates were not different (pooled OR 1.35, 95% CI 0.91 to 2.00, p=0.14). Women who received progestin and metformin achieved pregnancy and live birth rates similar to those who received progestin therapy only (pooled OR 1.01, 95% CI 0.44 to 2.35, p=0.98; pooled OR 0.46, 95% CI 0.21 to 1.03, p=0.06).

CONCLUSION

For reproductive-aged women with atypical endometrial hyperplasia or early endometrial cancer, progestin and metformin therapy compared with progestin therapy alone is associated with lower relapse rates, and similar remission, clinical pregnancy and live birth rates.

PROSPERO REGISTRATION NUMBER

CRD42020179069.disease remission.

The role of prolonged progestin treatment and factors predicting successful fertility-sparing treatment for early endometrial endometrioid adenocarcinoma

OBJECTIVE

Fertility-sparing progestin therapy is highly effective in selected young women with endometrial cancer. In present study, we attempted to evaluate the role of prolonged medication and identify factors predicting successful treatment, and also assess fertility outcomes among young women with early stage endometrial endometrioid carcinoma (EC).

STUDY DESIGN

We retrospectively reviewed clinical data from patients aged <45 years with well-differentiated EC at presumed stage IA (without myometrial invasion) who wished to preserve fertility. They were managed with oral progestin at Kaohsiung Chang Gung Memorial Hospital between June 2005 and June 2019.

RESULTS

Forty-five patients were included with a median follow-up of 53.5 months (range 12-170 months). Forty-one patients (91.1%) had complete remission, the cumulative complete response (CR) rates at 3, 6, 9, 12, and >12 months were 17.7%, 48.9%, 60.0%, 68.9% and 91.1%, respectively. Among the 41 responders, 23 attempted to conceive and nine (39.1%) achieved pregnancy with 12 live newborn infants. Eleven (27.5%) responders experienced recurrence at a median of 22 months from CR (range 3-54 months). Multivariate Cox regression analysis revealed that non-diabetes (HR: 4.59; 95% CI: 1.62-12.98) and endometrial thickness <2 cm (HR: 0.39; 95% CI: 1.41-17.67) were significantly factors associated with treatment response.

CONCLUSIONS

We concluded that prolonged oral progestin treatment was possible with a certain proportion of responders (24.4%) being responded after one year. Diabetes controlled on metformin and endometrial thickness <2 cm could be used as surrogate markers to predict better treatment response.

Medroxyprogesterone Reverses Tolerable Dose Metformin-Induced Inhibition of Invasion via Matrix Metallopeptidase-9 and Transforming Growth Factor-β1 in KLE Endometrial Cancer Cells

This study was performed to evaluate the anticancer effects of tolerable doses of metformin with or without medroxyprogesterone (MPA) in endometrial cancer cells. Cell viability, cell invasion, and levels of matrix metallopeptidase (MMP) and transforming growth factor (TGF)-β1 were analyzed using three human endometrial adenocarcinoma cell lines (Ishikawa, KLE, and uterine serous papillary cancer (USPC)) after treatment with different dose combinations of MPA and metformin. Combining metformin (0, 100, 1000 µM) and 10 µM MPA induced significantly decreased cell viability in a time- and dose-dependent manner in Ishikawa cells, but not in KLE and USPC cells. In KLE cells, metformin treatment alone significantly inhibited cell invasion in a dose-dependent manner. The inhibitory effect of metformin was reversed when 10 µM MPA was combined, which was significantly inhibited again after treatment of MMP-2/9 inhibitor and/or TGF-β inhibitor. Changes of MMP-9 and TGF-β1 according to combinations of MPA and metformin were similar to those of invasion in KLE cells. In conclusion, the anticancer effects of tolerable doses of metformin varied according to cell type and combinations with MPA. Anti-invasive effect of metformin in KLE cells was completely reversed by the addition of MPA; this might be associated with MMP-9 and TGF-β1.

mTOR-Dependent Role of Sestrin2 in Regulating Tumor Progression of Human Endometrial Cancer

Simple Summary

Mammalian target of rapamycin complex 1 (mTORC1), a key controller of growth and environmental stress signaling, is frequently activated in human cancers. Sestrin2 (SESN2), a highly conserved stress-inducible protein, is one of the negative feedback mechanisms for inhibiting chronic activation of mTORC1. This study aimed to investigate the expression and clinical implications of SESN2 in endometrial cancer using an in vitro and in vivo approach. The analysis indicated increased levels of SESN2 and mTORC1 pathway activity in cancer tissues than in normal tissues. High SESN2 expression correlated with shorter patient survival duration. However, lentiviral overexpression of SESN2 and mTOR inhibitors suppressed cancer cell proliferation, migration, and epithelial–mesenchymal transition. Our study provides strong evidence for prognostic significance of SESN2, and its association with mTORC1 pathway and endometrial cancer growth. Thus, the results identified SESN2 as a potential therapeutic target in endometrial cancer.

Abstract

Oncogenic activation of the mammalian target of rapamycin complex 1 (mTORC1) leads to endometrial cancer cell growth and proliferation. Sestrin2 (SESN2), a highly conserved stress-inducible protein, is involved in homeostatic regulation via inhibition of reactive oxygen species (ROS) and mTORC1. However, the role of SESN2 in human endometrial cancer remains to be investigated. Here, we investigated expression, clinical significance, and underlying mechanisms of SESN2 in endometrial cancer. SESN2 was upregulated more in endometrial cancer tissues than in normal endometrial tissues. Furthermore, upregulation of SESN2 statistically correlated with shorter overall survival and disease-free survival in patients with endometrial cancer. SESN2 expression strongly correlated with mTORC1 activity, suggesting its impact on prognosis in endometrial cancer. Additionally, knockdown of SESN2 promoted cell proliferation, migration, and ROS production in endometrial cancer cell lines HEC-1A and Ishikawa. Treatment of these cells with mTOR inhibitors reversed endometrial cancer cell proliferation, migration, and epithelial–mesenchymal transition (EMT) marker expression. Moreover, in a xenograft nude mice model, endometrial cancer growth increased by SESN2 knockdown. Thus, our study provides evidence for the prognostic significance of SESN2, and a relationship between SESN2, the mTORC1 pathway, and endometrial cancer growth, suggesting SESN2 as a potential therapeutic target in endometrial cancer.

Therapeutic effect of metformin in the treatment of endometrial cancer

The present review aims at reviewing the role of metformin in the treatment of endometrial cancer (EC). According to the literature, excessive estrogen levels and insulin resistance are established risk factors of EC. As a traditional insulin sensitizer and newly discovered anticancer agent, metformin directly and indirectly inhibits the development of EC. The direct mechanisms of metformin include inhibition of the LKB1-AMP-activated protein kinase-mTOR, PI3K-Akt and insulin-like growth factor 1-related signaling pathways, which reduces the proliferation and promotes the apoptosis of EC cells. In the indirect mechanism, metformin increases the insulin sensitivity of body tissues and decreases circulating insulin levels. Decreased levels of insulin increase the blood levels of sex hormone binding globulin, which leads to reductions in circulating estrogen and androgens. The aforementioned findings suggest that metformin serves an important role in the treatment of EC. Increased understanding of the mechanism of metformin in EC may provide novel insights into the treatment of this malignancy.

Pathogenesis and Clinical Management of Uterine Serous Carcinoma

Uterine serous carcinoma (USC) is an aggressive variant of endometrial cancer that has not been well characterized. It accounts for less than 10% of all endometrial cancers and 80% of endometrial cancer–related deaths. Currently, staging surgery together with chemotherapy or radiotherapy, especially vaginal cuff brachytherapy, is the main treatment strategy for USC. Whole-exome sequencing combined with preclinical and clinical studies are verifying a series of effective and clinically accessible inhibitors targeting frequently altered genes, such as HER2 and PI3K3CA, in varying USC patient populations. Some progress has also been made in the immunotherapy field. The PD-1/PD-L1 pathway has been found to be activated in many USC patients, and clinical trials of PD-1 inhibitors in USC are underway. This review updates the progress of research regarding the molecular pathogenesis and putative clinical management of USC.