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Background: In this study we evaluated the interactions of human adipose tissue-derived stem cells (ADSCs) and different human breast cancer cell lines (BRCAs) with regard to the safety of cell-assisted lipotransfers for breast reconstruction and a thereby unintended co-localization of ADSCs and BRCAs.
Methods: ADSCs were co-cultured with five different human BRCAs (MCF-7, MDA-MB-231, SK-BR-3, ZR-75-30, and EVSA-T) and primary BRCAs from one patient in a transwell system, and cell-cell-interactions were analyzed by assessing doubling time, migration and invasion, angiogenesis, quantitative real-time polymerase chain reaction (PCR) of more than 300 tumor-associated genes, and multiplex protein assays of 20 chemokines and growth factors and eight matrix metalloproteinases (MMPs). Results of co-culture were compared to those of the respective monoculture.
Results: Quantitative real-time PCR revealed remarkable changes in the expression of multiple tumor-associated genes in co-culture compared to monocultures of both ADSCs and BRCAs. Concomitantly, the concentration of several tumor-associated proteins, such as cytokines and MMPs, were strongly increased in co-culture. Furthermore, exclusively in co-culture with ADSCs, the different BRCAs were exposed to several important tumor-modulating proteins, such as CCL2, HGF, or interleukins.
Co-culture did not significantly affect cellular proliferation of either ADSCs or BRCAs (p > 0.05). The migration of MCF-7 and MDA-MB-231 BRCAs was significantly increased in co-culture with ADSCs by a mean of 11% and 23%, respectively (p = 0.04 and 0.012), as well as that of ADSCs in co-culture with MDA-MB-231, ZR-75-30, and EVSA-T (+11–15%, p = 0.035–0.045). Co-culture with MDA-MB-231, SK-BR-3, and EVSA-T BRCAs significantly increased the invasive behavior of ADSCs by a mean of 24–41% (p = 0.014–0.039). There were no significant differences in the in vitro invasive properties of BRCAs in co-culture compared to monoculture. An in vitro angiogenesis assay revealed an increased tube formation of conditioned media from co-cultured BRCAs and ADSCs compared to the respective monocultures.
Conclusion: This study further elucidates the possible interactions of primary human ADSCs with human BRCAs, pointing towards a potential increased oncological risk which should not be neglected when considering a clinical use of cell-assisted lipoaspirates in breast reconstruction.
Objective: Chronically HCV-infected orthotopic liver transplantation (OLT) recipients appear to have improved outcomes when their immunosuppressive regimen includes a mammalian target of rapamycin (mTOR) inhibitor. The mechanism underlying this observation is unknown.
Design: We used virological assays to investigate mTOR signalling on the HCV replication cycle. Furthermore, we analysed HCV RNA levels of 42 HCV-positive transplanted patients treated with an mTOR inhibitor as part of their immunosuppressive regimen.
Results: The mTOR inhibitor rapamycin was found to be a potent inhibitor for HCV RNA replication in Huh-7.5 cells as well as primary human hepatocytes. Half-maximal inhibition was observed at 0.01 µg/mL, a concentration that is in the range of serum levels seen in transplant recipients and does not affect cell proliferation. Early replication cycle steps such as cell entry and RNA translation were not affected. Knockdown of raptor, an essential component of mTORC1, but not rictor, an essential component of mTORC2, inhibited viral RNA replication. In addition, overexpression of raptor led to higher viral RNA replication, demonstrating that mTORC1, but not mTORC2, is required for HCV RNA replication. In 42 HCV-infected liver-transplanted or kidney-transplanted patients who were switched to an mTOR inhibitor, we could verify that mTOR inhibition decreased HCV RNA levels in vivo.
Conclusions: Our data identify mTORC1 as a novel HCV replication factor. These findings suggest an underlying mechanism for the observed benefits of mTOR inhibition in HCV-positive OLT recipients and potentiate further investigation of mTOR-containing regimens in HCV-positive recipients of solid organ transplants.