Positive effects of hypoxic preconditioning of the extracellular matrix and stromal vascular fraction from adipose tissue

Background

Numerous approaches have been developed to decelerate the aging process of facial skin. Synthetic fillers and cell-enriched fat grafts are the main procedures employed to fill wrinkles.

Objective

The aim of this study was to evaluate the in vitro and in vivo safety and efficiency of a new process developed by SYMBIOKEN: the AmeaCell, which facilitates the extraction of the stromal vascular fraction (SVF) and the associated hypoxia pre-conditioned matrix to promote fat graft survival.

Methods

The AmeaCell device allows the extraction from adipose tissue of SVF and pre-conditioned MatriCS and promotes a hypoxic environment. Experiments were carried out on human cells and then in mice.

Results

Characterization of cells and MatriCS showed that after their extraction using the new process developed by SYMBIOKEN, the extracted cells expressed stem-cell markers. The presence of characteristic proteins and lipid fractions found in the adipose matrix were confirmed in MatriCS. Cobalt chloride treatment of the matrix using the AmeaCell device induced modifications in the matrix composition with a decrease in laminin and without collagen modification, both of which promote adhesion and differentiation of SVF or adipose-derived stromal cells. The combination of MatriCS and SVF (1 × 106 and 5 × 106, respectively) is safe and efficient to fill winkles induced by UVB irradiation. The cross-talk between MatriCS and SVF can act a durable filler compared to the filling performed using cells or matrix or fat alone, which need to be replaced frequently.

Conclusion

These results indicate that the combination of MatriCS and SVF is safe and effective as a biological filler for achieving skin rejuvenation and wrinkle filling.

Mammary adipocytes stimulate breast cancer invasion through metabolic remodeling of tumor cells

In breast cancer, a key feature of peritumoral adipocytes is their loss of lipid content observed both in vitro and in human tumors. The free fatty acids (FFAs), released by adipocytes after lipolysis induced by tumor secretions, are transferred and stored in tumor cells as triglycerides in lipid droplets. In tumor cell lines, we demonstrate that FFAs can be released over time from lipid droplets through an adipose triglyceride lipase-dependent (ATGL-dependent) lipolytic pathway. In vivo, ATGL is expressed in human tumors where its expression correlates with tumor aggressiveness and is upregulated by contact with adipocytes. The released FFAs are then used for fatty acid β-oxidation (FAO), an active process in cancer but not normal breast epithelial cells, and regulated by coculture with adipocytes. However, in cocultivated cells, FAO is uncoupled from ATP production, leading to AMPK/acetyl-CoA carboxylase activation, a circle that maintains this state of metabolic remodeling. The increased invasive capacities of tumor cells induced by coculture are completely abrogated by inhibition of the coupled ATGL-dependent lipolysis/FAO pathways. These results show a complex metabolic symbiosis between tumor-surrounding adipocytes and cancer cells that stimulate their invasiveness, highlighting ATGL as a potential therapeutic target to impede breast cancer progression.

Inhibition of the GTPase Rac1 mediates the antimigratory effects of metformin in prostate cancer cells

Cell migration is a critical step in the progression of prostate cancer to the metastatic state, the lethal form of the disease. The antidiabetic drug metformin has been shown to display antitumoral properties in prostate cancer cell and animal models; however, its role in the formation of metastases remains poorly documented. Here, we show that metformin reduces the formation of metastases to fewer solid organs in an orthotopic metastatic prostate cancer cell model established in nude mice. As predicted, metformin hampers cell motility in PC3 and DU145 prostate cancer cells and triggers a radical reorganization of the cell cytoskeleton. The small GTPase Rac1 is a master regulator of cytoskeleton organization and cell migration. We report that metformin leads to a major inhibition of Rac1 GTPase activity by interfering with some of its multiple upstream signaling pathways, namely P-Rex1 (a Guanine nucleotide exchange factor and activator of Rac1), cAMP, and CXCL12/CXCR4, resulting in decreased migration of prostate cancer cells. Importantly, overexpression of a constitutively active form of Rac1, or P-Rex, as well as the inhibition of the adenylate cyclase, was able to reverse the antimigratory effects of metformin. These results establish a novel mechanism of action for metformin and highlight its potential antimetastatic properties in prostate cancer.

Postnatal soluble FGFR3 therapy rescues achondroplasia symptoms and restores bone growth in mice

Achondroplasia is a rare genetic disease characterized by abnormal bone development, resulting in short stature. It is caused by a single point mutation in the gene coding for fibroblast growth factor receptor 3 (FGFR3), which leads to prolonged activation upon ligand binding. To prevent excessive intracellular signaling and rescue the symptoms of achondroplasia, we have developed a recombinant protein therapeutic approach using a soluble form of human FGFR3 (sFGFR3), which acts as a decoy receptor and prevents FGF from binding to mutant FGFR3. sFGFR3 was injected subcutaneously to newborn Fgfr3(ach/+) mice-the mouse model of achondroplasia-twice per week throughout the growth period during 3 weeks. Effective maturation of growth plate chondrocytes was restored in bones of treated mice, with a dose-dependent enhancement of skeletal growth in Fgfr3(ach/+) mice. This resulted in normal stature and a significant decrease in mortality and associated complications, without any evidence of toxicity. These results describe a new approach for restoring bone growth and suggest that sFGFR3 could be a potential therapy for children with achondroplasia and related disorders.

Adipocyte-derived fibroblasts promote tumor progression and contribute to the desmoplastic reaction in breast cancer

Cancer-associated fibroblasts (CAF) comprise the majority of stromal cells in breast cancers, yet their precise origins and relative functional contributions to malignant progression remain uncertain. Local invasion leads to the proximity of cancer cells and adipocytes, which respond by phenotypical changes to generate fibroblast-like cells termed as adipocyte-derived fibroblasts (ADF) here. These cells exhibit enhanced secretion of fibronectin and collagen I, increased migratory/invasive abilities, and increased expression of the CAF marker FSP-1 but not α-SMA. Generation of the ADF phenotype depends on reactivation of the Wnt/β-catenin pathway in response to Wnt3a secreted by tumor cells. Tumor cells cocultivated with ADFs in two-dimensional or spheroid culture display increased invasive capabilities. In clinical specimens of breast cancer, we confirmed the presence of this new stromal subpopulation. By defining a new stromal cell population, our results offer new opportunities for stroma-targeted therapies in breast cancer.

[New perspectives for metformin in cancer therapy]

Cancer and type II diabetes are two diseases that appear to be associated. In fact, diabetes increases the incidence of several cancers (colon, endometrium, rectum and breast). Retrospective epidemiological studies show that metformin, a drug commonly used in type II diabetes, has antitumor properties. Therefore, many experimental studies (in vivo and in vitro) have been initiated in recent years to understand the cellular and molecular mechanisms that may explain the protective effects of metformin against cancer. Two main mode of action have been proposed. The first, indirect, involves the decrease of insulinemia. The second, via a direct action on cells, results in the regulation of the activated AMPK kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, which plays a central role in many cellular processes such as energy metabolism, protein synthesis, autophagy and apoptosis. Here, we review recent results concerning the antitumor action of metformin: epidemiological, metabolic, cellular and molecular levels. Ongoing experimental and clinical trials should help us better understand the mechanisms of action of metformin and allow us to determine whether the drug can be used in the treatment of cancer.

Sestrin2 integrates Akt and mTOR signaling to protect cells against energetic stress-induced death

The phosphoinositide-3 kinase/Akt (PI3K/Akt) pathway has a central role in cancer cell metabolism and proliferation. More importantly, it is one of the cardinal pro-survival pathways mediating resistance to apoptosis. The role of Akt in response to an energetic stress is presently unclear. Here, we show that Sestrin2 (Sesn2), also known as Hi95, a p53 target gene that protects cells against oxidative and genotoxic stresses, participates in the protective role of Akt in response to an energetic stress induced by 2-deoxyglucose (2-DG). Sesn2 is upregulated in response to an energetic stress such as 2-DG and metformin, and mediates the inhibition of mammalian target of rapamycin (mTOR), the major cellular regulator of energy metabolism. The increase of Sesn2 is independent of p53 but requires the anti-apoptotic pathway, PI3K/Akt. Inhibition of Akt, as well as loss of Sesn2, sensitizes cells to 2-DG-induced apoptosis. In addition, the rescue of Sesn2 partially reverses the pro-apoptotic effects of 2-DG. In conclusion, we identify Sesn2 as a new energetic stress sensor, which appears to be protective against energetic stress-induced apoptosis that integrates the pro-survival function of Akt and the negative regulation of mTOR.

Cancer-associated adipocytes exhibit an activated phenotype and contribute to breast cancer invasion

Early local tumor invasion in breast cancer results in a likely encounter between cancer cells and mature adipocytes, but the role of these fat cells in tumor progression remains unclear. We show that murine and human tumor cells cocultivated with mature adipocytes exhibit increased invasive capacities in vitro and in vivo, using an original two-dimensional coculture system. Likewise, adipocytes cultivated with cancer cells also exhibit an altered phenotype in terms of delipidation and decreased adipocyte markers associated with the occurrence of an activated state characterized by overexpression of proteases, including matrix metalloproteinase-11, and proinflammatory cytokines [interleukin (IL)-6, IL-1β]. In the case of IL-6, we show that it plays a key role in the acquired proinvasive effect by tumor cells. Equally important, we confirm the presence of these modified adipocytes in human breast tumors by immunohistochemistry and quantitative PCR. Interestingly, the tumors of larger size and/or with lymph nodes involvement exhibit the higher levels of IL-6 in tumor surrounding adipocytes. Collectively, all our data provide in vitro and in vivo evidence that (i) invasive cancer cells dramatically impact surrounding adipocytes; (ii) peritumoral adipocytes exhibit a modified phenotype and specific biological features sufficient to be named cancer-associated adipocytes (CAA); and (iii) CAAs modify the cancer cell characteristics/phenotype leading to a more aggressive behavior. Our results strongly support the innovative concept that adipocytes participate in a highly complex vicious cycle orchestrated by cancer cells to promote tumor progression that might be amplified in obese patients.

Adipose Tissue Increase Dramatically the Tumour Growth When Co-Injected with Breast Cancer Cell Lines: A Prudence Recommendation for Autologous Fat Transfer in Breast

Background: Autologous fat transfer takes an increasingly importance in plastic surgery. Indeed during the last decade, fat transfer was first of all used for breast reconstruction and now in breast augmentation, breast asymmetry, breast defects after lumpectomy and in some other breast deformation. Nevertheless this extension of the technique in the mammary parenchyma raises several questions. One of the most crucial interrogation is related to the type of interaction induced by the adipose tissue grafted with the breast cancer cells, interaction which remains poorly understood. Data from the literature evoked that these interactions lead to induce the increase of tumour growth properties. To decipher this interrogation, we designed experiments whose aims are to better understand and evaluate the actions and interactions induced by the xenograft of adipose tissue plus breast cancer cells in terms of tumour growth properties.Method: To study the impact of fat in tumours growth properties, we performed experiments of co-implantation of a panel of breast cancer cell lines (two humans: MDAMB-231 and SUM-159 PT ; and one mice: 67NR) with human adipose tissue from abdominal liposuction in nude mice. It was reported that tumour progression is the product of an evolving cross talk between tumour cells and its surrounding supportive tissue, the tumour stroma. Since mature adipocytes are radioresistant compared to other components of the tumour stroma, we investigated the effect of irradiated (15 Gray) or not adipose tissue on tumour growth properties. In each experiment we used 3 groups. The first one xenografted with cell lines only, the second one xenografted with cell plus fat and in the last constituted of cell plus irradiated fat. At the end of experiments mice were sacrificed and tumours were removed, dissected and one part was fixed and the other one (piece 2mm3) was re-implanted in a new mice. In these new groups we also studied the tumours growth and tumours tissue as previously described to evaluate the “possible” long time effect.Results-discussion: We have showed, whatever the cell line, that co-implantation of human fat (irradiated or not) with breast cancer cell lines induces a dramatic increase in tumour growth properties compared to cell line alone. Furthermore, the preliminary in vitro results associated to the ongoing immunohistochemistry analysis performed in the tumours from in vivo experiments of co-injection of fat plus breast cancer cell lines, gives related-results in term of tumour growth properties such as those observed in the in vivo experiment. Even-if larger in vitro studies are needed and are ongoing to consolidate our in vivo results, the whole of these results lead us to emit a recommendation of prudence with respect to this technique in mammary parenchyma.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3102.

Simultaneous determination of allantoin, hypoxanthine, xanthine, and uric acid in serum/plasma by CE

Allantoin (All) is an oxidative end product of purines in mammals. The small amount of All present in human plasma or serum results from free radical action on urate and may provide a stable marker of in vivo free radical activity. Because free radicals have been implicated in the development and progression of atherosclerosis, this study focused on the metabolic compounds of the All pathway. We propose a new fast CE (CE/UV) method for the simultaneous determination of All, uric acid (UA), hypoxanthine (HX), and xanthine (X) in human plasma. These products were quantified in the plasma of patients with chronic renal failure before hemodialysis (n = 6), patients with chronic heart failure (n = 6) and controls (n = 6). The filtered plasma were diluted ten-fold before the direct injection in CE/UV (195 nm), which allows separating the four compounds in less than 13 min. The metabolites were detectable at concentrations of 0.3-0.6 micromol/L. The method was linear over the range 0.5-150 micromol/L for All, HX, and X and 10-1500 micromol/L for UA (r > 0.99). The analytical performance of this method is satisfactory with intra-assay CV < 3.4%, inter-assay CV < 5% (HX and X < 7%), and recovery (93-101%). The proposed CE-UV method appears to be a useful tool for studying physiological and pathological changes of HX, UA, and All levels in plasma samples, the latter being a possible indicator of free radical damage in vivo.