Abstract PR15: Antitumor effect of metformin in breast cancer is associated with AMPK and FOXO3a activation
Bibliographic record
Abstract
Abstract Epidemiological studies have associated obesity with a wide variety of cancers such as metastatic breast cancer. Insulin resistance and hyperinsulinemia have been proposed as the mechanisms by which obesity induces or promotes tumorigenesis. Metformin, an anti-diabetic drug commonly prescribed to treat type 2 diabetes, has recently received attention as a potentially useful therapeutic agent for reducing cancer risk. It is reported to not only have a direct antitumoral effect, but also to act indirectly to improve insulin sensitivity, decreases hyperinsulinemia, and consequently attenuate tumor proliferation. The objective of the present study was to examine the influence of obesity in an experimental breast tumor model and to analyze the effect of metformin on it. Obesity was induced in newborn male Wistar rats by subcutaneous injection of 400mg/kg body weight monosodium glutamate (MSG) (obese) or saline (control) at 2, 3, 4, 5 and 6 days of age. After 16 weeks, 1x107 Walker-256 tumor cells, a rat breast carcinosarcoma cell lines, were subcutaneously injected in the right flank of the rats and concomitantly were treated with metformin (300mg/kg body weight, via gavage, for 15 days). Following this treatment, the rats were divided into 4 groups: control tumor (CT), control tumor metformin (CTM), obese tumor (OT) and obese tumor metformin (OTM). The effect of metformin on tumor development was assessed at the 18th week. Tumor development was higher in OT rats compared with CT rats which correlated with reduced life span in OT compared with CT rats. Metformin reduced the tumor development in OT rats and prolonged the life span of the rats. Metformin increased the mRNA expression of cell cycle regulators pRb and p27. Furthermore, metformin increased AMPK and FOXO3a activities, and decreased p-p38 and p-ERK1/2 expression in CTM and OTM groups. In order to further explore the molecular mechanism of the antiproliferative role of metformin, breast cancer MCF-7 cells were treated with metformin for 24, 48 and 72 hours. Results indicated that the antiproliferative effect of metformin was both time- and dose-dependent. This effect was associated with an increase in oxidative stress, apoptosis, necrosis and cell cycle arrest in G0-G1 phase as measured by flow cytometry. Metformin also increased mRNA expression of FOXO3a, p27, Bax and decreased the mRNA expression of cyclin D1 and Bcl-2 as well as decreased the Bcl-2 protein expression. Furthermore, metformin increased AMPK and FOXO3a activities. Moreover, the combination of metformin+2-deoxyglucose, an inhibitor of glycolysis, as well as metformin+H2O2 exhibited an even stronger antiproliferative effect as compared to the individual treatments. In conclusion, we have demonstrated that obesity has an important role in tumor development, increasing the tumor size and reducing the life span of the rats. We have also demonstrated that metformin was effective in controlling tumor development and prolonging the survival; effects associated with AMPK and FOXO3a. Financial support: FAPESP and CNPq (Brazil), NSERC-RCD and NOSM (Canada). This abstract is also presented as Poster A97. Citation Format: Eveline A. I. Fonseca, Maria Aparecida Oliveira, Rosangela Eichler, Eliana H. Akamine, Maria Helena C. Carvalho, Aneli M. Barbosa, Robert F. H. Dekker, Neelam Khaper, Zuleica B. Fortes. Antitumor effect of metformin in breast cancer is associated with AMPK and FOXO3a activation. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr PR15.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".