Accumulating evidence suggests that exposures to elevated levels of either endogenous estrogen or environmental estrogenic chemicals are associated with breast cancer development and progression. These natural or synthetic estrogens are known to produce reactive oxygen species (ROS) and increased ROS has been implicated in both cellular apoptosis and carcinogenesis. Though there are several studies on direct involvement of ROS in cellular apoptosis using short-term exposure model, there is no experimental evidence to directly implicate chronic exposure to ROS in increased growth and tumorigenicity of breast cancer cells. Therefore, the objective of this study was to evaluate the effects of chronic oxidative stress on growth, survival and tumorigenic potential of MCF-7 breast cancer cells. MCF-7 cells were exposed to exogenous hydrogen peroxide (H2O2) as a source of ROS at doses of 25 µM and 250 µM for acute (24 hours) and chronic period (3 months) and their effects on cell growth/survival and tumorigenic potential were evaluated. The results of cell count, MTT and cell cycle analysis showed that while acute exposure inhibits the growth of MCF-7 cells in a dose-dependent manner, the chronic exposure to H2O2-induced ROS leads to increased cell growth and survival of MCF-7 cells. This was further confirmed by gene expression analysis of cell cycle and cell survival related genes. Significant increase in number of soft agar colonies, up-regulation of pro-metastatic genes VEGF, WNT1 and CD44, whereas down-regulation of anti-metastatic gene E-Cadherin in H2O2 treated MCF-7 cells observed in this study further suggests that persistent exposure to oxidative stress increases tumorigenic and metastatic potential of MCF-7 cells. Since many chemotherapeutic drugs are known to induce their cytotoxicity by increasing ROS levels, the results of this study are also highly significant in understanding the mechanism for adaptation to ROS-induced toxicity leading to acquired chemotherapeutic resistance in breast cancer cells.

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Background Conventional preclinical models often miss drug toxicities, meaning the harm these drugs pose to humans is only realized in clinical trials or when they make it to market. This has caused the pharmaceutical industry to waste considerable time and resources developing drugs destined to fail. Organ-on-a-Chip technology has the potential improve success in drug development pipelines, as it can recapitulate organ-level pathophysiology and clinical responses; however, systematic and quantitative evaluations of Organ-Chips’ predictive value have not yet been reported. Methods 870 Liver-Chips were analyzed to determine their ability to predict drug-induced liver injury caused by small molecules identified as benchmarks by the Innovation and Quality consortium, who has published guidelines defining criteria for qualifying preclinical models. An economic analysis was also performed to measure the value Liver-Chips could offer if they were broadly adopted in supporting toxicity-related decisions as part of preclinical development workflows. Results Here, we show that the Liver-Chip met the qualification guidelines across a blinded set of 27 known hepatotoxic and non-toxic drugs with a sensitivity of 87% and a specificity of 100%. We also show that this level of performance could generate over $3 billion annually for the pharmaceutical industry through increased small-molecule R&D productivity. Conclusions The results of this study show how incorporating predictive Organ-Chips into drug development workflows could substantially improve drug discovery and development, allowing manufacturers to bring safer, more effective medicines to market in less time and at lower costs.

Oxidative injury to cellular macromolecules has been suggested as a common pathway shared by multiple etiological factors for kidney cancer. Whether the chronic oxidative stress alone is sufficient to induce malignant transformation in human kidney cells is not clear. Therefore, the objective of this study was to evaluate the effect of H2O2-induced chronic oxidative stress on growth, and malignant transformation of HK-2 normal kidney epithelial cells. This study revealed that chronic oxidative stress causes increased growth and neoplastic transformation in normal kidney epithelial cells at non-cytotoxic dose and increased adaptation to cytotoxic level. This was confirmed by gene expression changes, cell cycle analysis, anchorage independent growth assay and in vivo tumorigenicity in nude mice. Stem cells characteristics as revealed by up-regulation of stem cell marker genes, and morphological changes indicative of EMT with up regulation of mesenchymal markers were also observed in cells exposed to chronic oxidative stress. Antioxidant NAC did not reverse the chronic oxidative stress-induced growth, and adaptation suggesting that perturbed biological function in these cells are permanent. Partial reversal of oxidative stress-induced growth, and adaptation by silencing of Oct 4 and Snail1, respectively, suggest that these changes are mediated by acquisition of stem cell and EMT characteristics. In summary, this study for the first time suggests that chronic exposure to elevated levels of oxidative stress is sufficient to induce malignant transformation in kidney epithelial cells through acquisition of stem cell characteristics. Additionally, the EMT plays an important role in increased adaptive response of renal cells to oxidative stress.

Human organ-on-a-chip (Organ-Chip) technology has the potential to disrupt preclinical drug discovery and improve success in drug development pipelines as it can recapitulate organ-level pathophysiology and clinical responses. The Innovation and Quality (IQ) consortium, formed by multiple pharmaceutical and biotechnology companies, has published guidelines that define criteria for qualifying preclinical models, however, systematic and quantitative evaluation of the predictive value of Organ-Chips has not yet been reported. Here, 780 Liver-Chips were analyzed to determine their ability to predict drug-induced liver injury (DILI) caused by small molecules identified as benchmarks by the IQ consortium. The Liver-Chip met the qualification guidelines across a blinded set of 27 known hepatotoxic and non-toxic drugs with a sensitivity of 80% and a specificity of 100%. A computational economic value analysis suggests that with this performance the Liver-Chip could generate $3 billion annually for the pharmaceutical industry due to increased R&D productivity.