Phenformin has anti-tumorigenic effects in human ovarian cancer cells and in an orthotopic mouse model of serous ovarian cancer.

Obesity and diabetes have been associated with increased risk and worse outcomes in ovarian cancer (OC). The biguanide metformin is used in the treatment of type 2 diabetes and is also believed to have anti-tumorigenic benefits. Metformin is highly hydrophilic and requires organic cation transporters (OCTs) for entry into human cells. Phenformin, another biguanide, was taken off the market due to an increased risk of lactic acidosis over metformin. However, phenformin is not reliant on transporters for cell entry; and thus, may have increased potency as both an anti-diabetic and anti-tumorigenic agent than metformin. Thus, our goal was to evaluate the effect of phenformin on established OC cell lines, primary cultures of human OC cells and in an orthotopic mouse model of high grade serous OC. In three OC cell lines, phenformin significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, caused cellular stress, inhibited adhesion and invasion, and activation of AMPK and inhibition of the mTOR pathway. Phenformin also exerted anti-proliferative effects in seven primary cell cultures of human OC. Lastly, phenformin inhibited tumor growth in an orthotopic mouse model of serous OC, coincident with decreased Ki-67 staining and phosphorylated-S6 expression and increased expression of caspase 3 and phosphorylated-AMPK. Our findings demonstrate that phenformin has anti-tumorigenic effects in OC as previously demonstrated by metformin but it is yet to be determined if it is superior to metformin for the potential treatment of this disease.

Dual inhibition of glycolysis and glutaminolysis as a therapeutic strategy in the treatment of ovarian cancer.

Cancer cell metabolism is required to support the biosynthetic demands of cell growth and cell division, and to maintain reduction oxidaton (redox) homeostasis. This study was designed to test the effects of glucose and glutamine on ovarian cancer cell growth and explore the inter-relationship between glycolysis and glutaminolysis. The SKOV3, IGROV-1 and Hey ovarian cancer cell lines were assayed for glucose, pyruvate and glutamine dependence by analyzing cytotoxicity, cell cycle progression, apoptosis and ATP production. As determined by MTT assay, glucose stimulated cell growth while the combination of glucose, glutamine and pyruvate resulted in the greatest stimulation of cell proliferation. Furthermore, 2-deoxy-glucose (2-DG) and 3-bromopyruvate (3-BP) induced apoptosis, caused G1 phase cell cycle arrest and reduced glycolytic activity. Moreover, 2-DG in combination with a low dose of aminooxyacetate (AOA) synergistically increased the sensitivity to 2-DG in the inhibition of cell growth in the ovarian cancer cell lines. These studies suggest that dual inhibition of glycolysis and glutaminolysis may be a promising therapeutic strategy for the treatment of ovarian cancer.

NT1014, a novel biguanide, inhibits ovarian cancer growth in vitro and in vivo.

BACKGROUND: NT1014 is a novel biguanide and AMPK activator with a high affinity for the organic cation-specific transporters, OCT1 and OCT3. We sought to determine the anti-tumorigenic effects of NT1014 in human ovarian cancer cell lines as well as in a genetically engineered mouse model of high-grade serous ovarian cancer. METHODS: The effects of NT1014 and metformin on cell proliferation were assessed by MTT assay using the human ovarian cancer cell lines, SKOV3 and IGROV1, as well as in primary cultures. In addition, the impact of NT1014 on cell cycle progression, apoptosis, cellular stress, adhesion, invasion, glycolysis, and AMPK activation/mTOR pathway inhibition was also explored. The effects of NT1014 treatment in vivo was evaluated using the K18 - gT121+/-; p53fl/fl; Brca1fl/fl (KpB) mouse model of high-grade serous ovarian cancer. RESULTS: NT1014 significantly inhibited cell proliferation in both ovarian cancer cell lines as well as in primary cultures. In addition, NT1014 activated AMPK, inhibited downstream targets of the mTOR pathway, induced G1 cell cycle arrest/apoptosis/cellular stress, altered glycolysis, and reduced invasion/adhesion. Similar to its anti-tumorigenic effects in vitro, NT1014 decreased ovarian cancer growth in the KpB mouse model of ovarian cancer. NT1014 appeared to be more potent than metformin in both our in vitro and in vivo studies. CONCLUSIONS: NT1014 inhibited ovarian cancer cell growth in vitro and in vivo, with greater efficacy than the traditional biguanide, metformin. These results support further development of NT1014 as a useful therapeutic approach for the treatment of ovarian cancer.

JQ1 suppresses tumor growth via PTEN/PI3K/AKT pathway in endometrial cancer.

Overexpression of c-Myc is associated with worse outcomes in endometrial cancer, indicating that c-Myc may be a promising target for endometrial cancer therapy. A novel small molecule, JQ1, has been shown to block BRD4 resulting in inhibition of c-Myc expression and tumor growth. Thus, we investigated whether JQ1 can inhibit endometrial cancer growth in cell culture and xenograft models. In PTEN-positive endometrial cancer cells, JQ1 significantly suppressed cell proliferation via induction of G1 phase arrest and apoptosis in a dose-dependent manner, accompanied by a sharp decline in cyclin D1 and CDK4 protein expression. However, PTEN-negative endometrial cancer cells exhibited intrinsic resistance to JQ1, despite significant c-Myc inhibition. Moreover, we found that PTEN and its downstream PI3K/AKT signaling targets were modulated by JQ1, as evidenced by microarray analysis. Silencing of PTEN in PTEN-positive endometrial cancer cells resulted in resistance to JQ1, while upregulation of PTEN in PTEN-negative endometrial cancer cells increased sensitivity to JQ1. In xenografts models of PTEN-positive and PTEN-knock-in endometrial cancer, JQ1 significantly upregulated the expression of PTEN, blocked the PI3K/AKT signaling pathway and suppressed tumor growth. These effects were attenuated in PTEN-negative and PTEN-knockdown xenograft models. Thus, JQ1 resistance appears to be highly associated with the status of PTEN expression in endometrial cancer. Our findings suggest that targeting BRD4 using JQ1 might serve as a novel therapeutic strategy in PTEN-positive endometrial cancers.

Buformin exhibits anti-proliferative and anti-invasive effects in endometrial cancer cells.

OBJECTIVE: Biguanides are anti-diabetic drugs that are thought to have anti-tumorigenic effects. Most pre-clinical studies have focused on metformin for cancer treatment and prevention; however, buformin may be potentially more potent than metformin. Given this, our goal was to evaluate the effects of buformin on cell growth, adhesion and invasion in endometrial cancer cell lines. METHODS: The ECC-1 and Ishikawa endometrial cancer cell lines were used. Cell proliferation was assessed by MTT assay. Apoptosis and cell cycle analysis was performed by FITC Annexin V assay and propidium iodide staining, respectively. Adhesion was analyzed using the laminin adhesion assay. Invasion was assessed using the transwell invasion assay. The effects of buformin on the AMPK/mTOR pathway were determined by Western immunoblotting. RESULTS: Buformin and metformin inhibited cell proliferation in a dose-dependent manner in both endometrial cancer cell lines. IC50s were 1.4-1.6 mM for metformin and 8-150 µM for buformin. Buformin induced cell cycle G1 phase arrest in the ECC-1 cells and G2 phase arrest in the Ishikawa cells. For both ECC-1 and Ishikawa cells, treatment with buformin resulted in induction of apoptosis, reduction in adhesion and invasion, activation of AMPK and inhibition of phosphorylated-S6. Buformin potentiated the anti-proliferative effects of paclitaxel in both cell lines. CONCLUSION: Buformin has significant anti-proliferative and anti-metastatic effects in endometrial cancer cells through modulation of the AMPK/mTOR pathway. IC50 values were lower for buformin than metformin, suggesting that buformin may be more potent for endometrial cancer treatment and worthy of further investigation.

JQ1 suppresses tumor growth through downregulating LDHA in ovarian cancer.

Amplification and overexpression of c-Myc is commonly seen in human ovarian cancers, and this could be a potentially novel therapeutic target for this disease. JQ1, a selective small-molecule BET bromodomain (BRDs) inhibitor, has been found to suppress tumor progression in several cancer cell types. Using ovarian cancer cell lines, a transgenic mouse model, and primary cell cultures from human ovarian cancer tissues, we demonstrated that JQ1 significantly suppressed cellular proliferation and induced cell cycle arrest and apoptosis in ovarian cancer cells and mouse model via targeting c-Myc. In addition, JQ1 had multiple influences on cancer metabolism, particularly in the aerobic glycolysis pathway. JQ1 reduced both the activity and phosphorylation of LDHA, inhibited lactate production, and decreased the energy supply to ovarian cancer cell lines and tumors. Taken together, our findings suggest that JQ1 is an efficacious anti-tumor agent in ovarian cancer that is associated with cell cycle arrest, induction of apoptosis and alterations of metabolism.

Evaluation of the anti-tumor effects of lactate dehydrogenase inhibitor galloflavin in endometrial cancer cells.

High rates of aerobic glycolysis represent a key mechanism by which endometrial cancer cells consume glucose as its primary energy source. The up-regulated glycolytic pathway is a common therapeutic target whose inhibition has implications for anti-tumor activity in cancer cells. The present study was aimed at evaluating the potential of a novel lactate dehydrogenase (LDH) inhibitor, Galloflavin, as a therapeutic agent for endometrial cancer. Our results revealed that Galloflavin effectively inhibited cell growth in endometrial cancer cell lines and primary cultures of human endometrial cancer through its involvement in multiple signaling pathways that regulate metabolism, cell cycle, apoptosis, cell stress and metastasis.

Obesity is associated with worse overall survival in women with low-grade papillary serous epithelial ovarian cancer.

OBJECTIVE: The objective of this study was to evaluate prognostic risk factors for survival in women with low-grade serous epithelial ovarian cancer (LGSC). METHODS: A multicenter retrospective analysis of patients with LGSC was conducted. Potential epidemiologic risk factors evaluated included obesity, age, parity, race, smoking, oral contraceptive pill and/or hormonal replacement therapy use, and previous hysterectomy or surgery on fallopian tubes and/or ovaries. Additional factors included stage, extent of debulking, residual disease, and disease status. RESULTS: Eighty-one patients were identified, and pathologic diagnosis was independently confirmed. Median age at diagnosis was 56 years (range, 21-86 years). Thirty-four percent were obese, and 80% had optimally debulked disease. Forty-six percent were alive, 14% with disease, whereas 25% were dead of disease, 2% died of intercurrent disease, and 27% had an unknown status. In a univariate analysis, optimal surgical debulking was associated with improved progression-free survival (P = 0.01), disease-specific survival (P = 0.03), and overall survival (OS) (P < 0.001) and body mass index with worse OS (P = 0.05). On multivariate analysis, obesity (hazard ratio, 2.8; 95% confidence interval, 1.05-7.3; P = 0.04) and optimal tumor debulking (hazard ratio, 0.05; 95% confidence interval, 0.008-0.29; P = 0.001) were a significant predictor of OS. CONCLUSIONS: In a multivariate analysis, obesity and optimal tumor cytoreduction were significant predictors of OS. However, obesity was not associated with worse disease-specific survival, suggesting that mortality of obese patients with LGSC may result from other comorbidities. Interventions addressing obesity may improve survival for women diagnosed with LGSC, and further study is warranted to address the role of obesity in LGSC.

Recurrence-free and 5-year survival following robotic-assisted surgical staging for endometrial carcinoma.

OBJECTIVE: The aim of this study is to report recurrence-free and overall survival for women with endometrial adenocarcinoma who were surgically staged using robotic-assisted laparoscopy. METHODS: A retrospective chart review was performed for all consecutive endometrial adenocarcinoma patients surgically staged with robotic-assisted laparoscopy at the University of North Carolina Hospital from 2005 to 2010. Demographic data, 5-year survival, and recurrence-free intervals were analyzed. Statistical analysis using Chi-square, t-test, and Kaplan-Meier curves were performed with SAS software. Study results were compared to endometrial cancer statistics from the Surveillance Epidemiology and End Results database from the National Cancer Institute. RESULTS: A total of 499 patients were identified and included in the study. Recurrence-free intervals after robotic-assisted surgical staging were 85.2% for stage IA, 80.2% for stage IB, 69.8% for stage II, and 69% for stage III. Projected 5-year survival was 88.7% for all patients included in the study. Nearly 82% of cases were endometrioid adenocarcinoma, with papillary serous, clear cell or mixed histology comprising 17.4% of cases. Median follow up time was 23 months, with a range of 0 to 80 months. Among stage IA, IB, II, and III patients, projected overall survival was 94.2%, 85.9%, 77.4%, and 68.6%, respectively. CONCLUSIONS: The results from this study demonstrate that robotic-assisted surgical staging for endometrial cancer does not adversely affect rates of recurrence or survival. These findings provide further evidence that robotic-assisted laparoscopic surgical staging is not associated with inferior results when compared to laparotomy or traditional laparoscopy.

Discussion: 'Surgical staging in early ovarian carcinoma' by Garcia-Soto et al.

In the roundtable that follows, clinicians discuss a study published in this issue of the Journal in light of its methodology, relevance to practice, and implications for future research.