The successful treatment of cancer has significantly improved as a result of targeted therapy and immunotherapy. However, during chemotherapy, cancer cells evolve and can acquire “multidrug ...resistance” (MDR), which significantly limits the efficacy of cancer treatment and impacts patient survival and quality of life. Among the approaches to reverse MDR, modulating reactive oxidative species (ROS) may represent a strategy to kill MDR cancer cells that are mechanistically diverse. ROS in cancer cells play a central role in regulating and inducing apoptosis, thereby modulating cancer cells proliferation, survival and drug resistance. The levels of ROS and the activity of scavenging/anti-oxidant enzymes in drug resistant cancer cells are typically increased compared to non-MDR cancer and normal cells. Consequently, MDR cancer cells may be more susceptible to alterations in ROS levels. Numerous studies suggest that compounds modulating cellular ROS levels can enhance MDR cancer cell death and sensitize MDR cancer cells to certain chemotherapeutic drugs.
In the current review, we discuss the critical and targetable redox-regulating enzymes, including mitochondrial electron transport chain (ETC) complexes, NADPH oxidases (NOXs), enzymes related to glutathione metabolism, glutamate/cystine antiporter xCT, thioredoxin reductases (TrxRs), nuclear factor erythroid 2-related factor 2 (Nrf2), and their roles in regulating cellular ROS levels, drug resistance as well as their clinical significance. We also discuss and summarize the findings in the past decade regarding the efficacy of ROS modulators for the treatment of MDR cancer alone or as sensitizing compounds. Compounds that are efficacious in modulating ROS generation represent a prominent class of drug candidates that warrants evaluation in clinical trials for patients harboring MDR cancers.
Reopening amid the COVID-19 pandemic has triggered a battle on social media. The supporters perceived that the lockdown policy could damage the economy and exacerbate social inequality. By contrast, ...the opponents believed it was necessary to contain the spread and ensure a safe environment for recovery. Anatomy into the battle is of importance to address public concerns, beliefs, and values, thereby enabling policymakers to determine the appropriate solutions to implement reopening policy. To this end, we investigated over 1.5 million related Twitter postings from April 17 to May 30, 2020. With the aid of natural language processing (NLP) techniques and machine learning classifiers, we classified each tweet into either a "supporting" or "opposing" class and then investigated the public perception from temporal and spatial perspectives. From the temporal dimension, we found that both political and scientific news that were extensively discussed on Twitter led to the perception of opposing reopening. Further, being the first mover with full reopen adversely affected the public reaction to reopening policy, while being the follower or late mover resulted in positive responses. From the spatial dimension, the correlation and regression analyses suggest that the state-level perception was very likely to be associated with political affiliation and health value.
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Drug resistance is a major obstacle in the field of pre-clinical and clinical therapeutics. The development of novel technologies and targeted therapies have yielded new modalities to ...overcome drug resistance, but multidrug resistance (MDR) remains one of the major challenges in the treatment of cancer. The ubiquitin-proteasome system (UPS) has a central role in regulating the levels and activities of a multitude of proteins as well as regulation of cell cycle, gene expression, response to oxidative stress, cell survival, cell proliferation and apoptosis. Therefore, inhibition of the UPS could represent a novel strategy for the treatment and overcoming of drug resistance in chemoresistant malignancies. In 2003, bortezomib was approved by the FDA for the treatment of multiple myeloma (MM). However, due to its limitations, second generation proteasome inhibitors (PIs) like carfilzomib, ixazomib, oprozomib, delanzomib and marizomib were introduced which displayed clinical activity in bortezomib-resistant tumors. Past studies have demonstrated that proteasome inhibition potentiates the anti-cancer efficacy of other chemotherapeutic drugs by: i) decreasing the expression of anti-apoptotic proteins such as TNF-α and NF-kB, ii) increasing the levels of Noxa, a pro-apoptotic protein, iii) activating caspases and inducing apoptosis, iv) degrading the pro-survival protein, induced myeloid leukemia cell differentiation protein (MCL1), and v) inhibiting drug efflux transporters. In addition, the mechanism of action of the immunoproteasome inhibitors, ONX-0914 and LU-102, suggested their therapeutic role in the combination treatment with PIs. In the current review, we discuss various PIs and their underlying mechanisms in surmounting anti-tumor drug resistance when used in combination with conventional chemotherapeutic agents.
Pavement rehabilitation is carbon intensive and the choice of pavement type is a critical factor in controlling greenhouse gas (GHG) emissions. The existing body of knowledge is not able to support ...decision-making on pavement choice due to a lack of consensus on the system boundaries, the functional units and the estimation periods. Excessive data requirements further inhibit the generalization of the existing methodologies for design evaluation at the early planning stage. This study proposes a practical life-cycle GHG estimation approach, which is arguably effective to benchmark pavement emissions given project bid tabulation. A set of case studies conducted for this study suggest that recycled asphalt pavement (e.g., foam stabilized base (FSB), and warm mix asphalt (WMA)) would prevent up to 50% of GHGs from the initial construction phase. However, from a life-cycle perspective, pavement emissions are dictated largely by the traffic characteristics and the analysis period for the use phase. The benefits from using recycled materials (e.g., FSB) are likely to diminish if the recycled products do not perform as well as those properly proportioned with less recycled materials, or if the recycled materials are locally unavailable. When the AADT reaches 10,000, use phase releases more than 97% of the life cycle emissions and the emissions difference among alternative designs will be within 1%.
•Greenhouse gases from pavement are quantified using bid tabulation at design phase.•Pavement layers and structural performance are factored into emission comparison.•Appropriate choice of materials reduces up to 50% of emissions from paving jobs.•Emissions from clearing and traffic delay contribute 17% and should not be ignored.•Cradle-to-grave emission is dictated largely by traffic volume and analysis period.
•JD-R model were used to depict what factors affect safety leadership.•Job characteristics and personal resources affect safety leadership via engagement.•Personal resources moderate how job ...characteristics affect engagement.
Although research has shown that safety leadership is a strong predictor of safety outcomes, it is unclear what factors lead to safety leadership. This unexplored area has hindered the development of effective interventions to promote safety leadership.This study addresses the knowledge gap by examining how job characteristics and personal resources influence construction leaders’ engagement in safety leadership based on the Job Demands-Resources (JD-R) model in positive psychology. An online survey was distributed to all managerial employees in a large U.S. construction organization, resulting in 383 valid responses. The structural equation modeling analysis indicates that job characteristics (social support, work autonomy and risk perception) and personal resources (psychological capital) significantly contribute to safety-specific transformational leadership through work engagement. Moreover, psychological capital moderates the effect of social support on leaders’ engagement in safety leadership. The implications of the present findings regarding safety leadership research are also discussed.
This study aimed to examine blood benzene, toluene, ethylbenzene, o-xylene, and m-/p-xylene (BTEX) concentrations and their trends contrasting construction workers with workers in other occupations ...from 1999 to 2014 in the United States. Methods: Using data from the National Health and Nutrition Examination Survey, quantile regressions were performed to investigate associations between occupation and blood BTEX concentrations. Results: We found that high-risk and construction occupations were associated with increased blood concentrations of toluene, o-xylene, and m-/p-xylene at the 50-90th percentiles (P 50-90 ), and ethylbenzene at P 70-90 . Moreover, although blood concentrations of ethylbenzene, o-xylene, and m-/p-xylene trended down among all US workers, no decreasing trend was observed for benzene and toluene among construction workers. Conclusions: Future studies are warranted to address questions about specific tasks to better assess VOC exposure from various trades.
This paper presents a simulation-based decision model for contract period determination in Energy Performance Contracting (EPC). The model attempts to assist the Energy Service Companies (ESCOs) on ...how long the contract period should be to balance the bidding competitiveness and the potential revenue loss. The uncertainties within the energy efficiency investment and the energy cost savings as return are addressed by stochastic processes, taking the maintenance and savings performance variations and the energy price fluctuations into account. Considering both the contract period and the energy cost savings guarantee, a framework is proposed to identify the profit sharing in EPC for both the owners and the ESCOs. An optimization model is derived accordingly, and the balanced length of the contract period is then reached. Finally, a campus case is presented to verify the applicability of the proposed model. The method can be used by industry practitioners as a decision support tool for contract period design, and is worth popularizing in other performance-based projects.
•A simulation-based decision model for designing contract period was presented.•Uncertainties within the energy performance were addressed by stochastic processes.•A framework was proposed to identify the profit sharing for the parties participated.•A campus case was presented to verify the applicability of the proposed model.
The development of multidrug resistance (MDR) to chemotherapy remains a major challenge in the treatment of cancer. Numerous mechanisms have been recognized that cause MDR, but one of the most ...important mechanisms is overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) transporters, through which the efflux of various anticancer drugs against their concentration gradients is powered by ATP. In recent years, small molecular tyrosine kinase inhibitors (TKIs) have been developed for treatment in various human cancers overexpressing epidermal growth factor receptor (EGFR). At the same time, some TKIs have been shown to be capable of inhibiting ABC transporter-mediated MDR. Dacomitinib (PF-00299804) is a second generation, irreversible TKI, which has shown positive anticancer activities in some preclinical and clinical trials. As many TKIs are substrates or inhibitors of ABC transporters, this study investigates whether dacomitinib could interact with ABC subfamily members that mediate MDR, including ABCB1 (P-gp), ABCG2 (BCRP) and ABCC1 (MRP1). The results showed that dacomitinib at 1.0 μM significantly reversed drug resistance mediated by ABCB1 and ABCG2, but not ABCC1, doing so by antagonizing the drug efflux function in ABCB1- and ABCG2-overexpressing cell lines. The reversal effect on ABCB1-overexpressing cells is more potent than that on ABCG2-overexpressing cells. In addition, dacomitinib at reversal concentration affected neither the protein expression level nor the localization of ABCB1 and ABCG2. Therefore, the mechanisms of this modulating effect are likely to be the following: first, as an inhibitor of ABCB1 or ABCG2 transporters, dacomitinib binds to drug-substrate site in transmembrane domains (TMD) stably in a noncompetitive manner; or second, dacomitinib inhibits ATPase activity and maintains the stability of TMD conformation in a concentration-dependent manner thereby inhibiting the drug efflux function of ABCB1 or ABCG2 transporter. This study provides a useful combinational therapeutic strategy with dacomitinib and substrates of ABCB1 and/or ABCG2 transporters in ABCB1- or ABCG2-overexpressing cancers.
•Dacomitinib, a selective and irreversible inhibitor of EGFR has advanced to several Phase III clinical trials for the treatment of non-small-cell lung carcinoma (NSCLC).•Dacominitib significantly enhanced the chemotherapeutic potential of anticancer drugs by blocking the function of ABCB1 and ABCG2 transporters.•Molecular docking analysis suggests that Dacomitinib interacts with ABCB1 within its large cavity located in the transmembrane region.•Combination of Dacomitinib and anticancer drugs can overcome ABCB1- or ABCG2-mediated drug resistance which is of great clinical interest.
Using an easily prepared triethylammonium N‐benzyldithiocarbamate salt as a sulfur source, a dual C−S functionalization of cyclic diaryliodoniums to form tricyclic thioheterocycles is realized. Our ...method uses the readily available copper sulfate to accelerate the chemical transformation under mild conditions. A broad range of cyclic diaryliodoniums with a ring size from 5‐ to 7‐membered can be employed to gain a quick access to tricyclic thioheterocycles including dibenzothiophenes, thioxanthenes, and phenoxathiines.
Reactive oxygen species (ROS) homeostasis and mitochondrial metabolism are critical for the survival of cancer cells, including cancer stem cells (CSCs), which often cause drug resistance and cancer ...relapse. Auranofin is a mono-gold anti-rheumatic drug, and it has been repurposed as an anticancer agent working by the induction of both ROS increase and mitochondrial dysfunction. Hypothetically, increasing auranofin’s positive charges via incorporating more gold atoms to enhance its mitochondria-targeting capacity could enhance its anti-cancer efficacy. Hence, in this work, both mono-gold and bi-gold compounds were designed and evaluated to test our hypothesis. The results showed that bi-gold compounds generally suppressed cancer cells proliferation better than their mono-gold counterparts. The most potent compound, BGC2a, substantially inhibited the antioxidant enzyme TrxR and increased the cellular ROS. BGC2a induced cell apoptosis, which could not be reversed by the antioxidant agent vitamin C, implying that the ROS induced by TrxR inhibition might not be the decisive cause of cell death. As expected, a significant proportion of BGC2a accumulated within mitochondria, likely contributing to mitochondrial dysfunction, which was further confirmed by measuring oxygen consumption rate, mitochondrial membrane potential, and ATP production. Moreover, BGC2a inhibited colony formation and reduced stem-like side population (SP) cells of A549. Finally, the compound effectively suppressed the tumor growth of both A549 and PANC-1 xenografts. Our study showed that mitochondrial disturbance may be gold-based compounds’ major lethal factor in eradicating cancer cells, providing a new approach to developing potent gold-based anti-cancer drugs by increasing mitochondria-targeting capacity.
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