The current predominant theapeutic paradigm is based on maximizing drug-receptor occupancy to achieve clinical benefit. This strategy, however, generally requires excessive drug concentrations to ensure sufficient occupancy, often leading to adverse side effects. Here, we describe major improvements to the proteolysis targeting chimeras (PROTACs) method, a chemical knockdown strategy in which a heterobifunctional molecule recruits a specific protein target to an E3 ubiquitin ligase, resulting in the target’s ubiquitination and degradation. These compounds behave catalytically in their ability to induce the ubiquitination of super-stoichiometric quantities of proteins, providing efficacy that is not limited by equilibrium occupancy. We present two PROTACs that are capable of specifically reducing protein levels by >90% at nanomolar concentrations. In addition, mouse studies indicate that they provide broad tissue distribution and knockdown of the targeted protein in tumor xenografts. Together, these data demonstrate a protein knockdown system combining many of the favorable properties of small-molecule agents with the potent protein knockdown of RNAi and CRISPR.

Androgen Receptor (AR)-dependent transcription is a major driver of prostate tumor cell proliferation. Consequently, it is the target of several antitumor chemotherapeutic agents, including the AR antagonist MDV3100/enzalutamide. Recent studies have shown that a single AR mutation (F876L) converts MDV3100 action from an antagonist to an agonist. Here we describe the generation of a novel class of Selective Androgen Receptor Degraders (SARDs) to address this resistance mechanism. Molecules containing hydrophobic degrons linked to small molecule Androgen Receptor (AR) ligands induce AR degradation, reduce expression of AR target genes and inhibit proliferation in androgen-dependent prostate cancer cell lines. These results suggest that selective AR degradation may be an effective therapeutic prostate tumor strategy in the context of AR mutations that confer resistance to third generation AR antagonists.

Transient mitochondrial stress can promote beneficial physiological responses and longevity, termed "mitohormesis." To interrogate mitohormetic pathways in mammals, we generated mice in which mitochondrial superoxide dismutase 2 (SOD2) can be knocked down in an inducible and reversible manner (iSOD2-KD mice). Depleting SOD2 only during embryonic development did not cause post-natal lethality, allowing us to probe adaptive responses to mitochondrial oxidant stress in adult mice. Liver from adapted mice had increased mitochondrial biogenesis and antioxidant gene expression and fewer reactive oxygen species. Gene expression analysis implicated non-canonical activation of the Nrf2 antioxidant and PPARγ/PGC-1α mitochondrial signaling pathways in this response. Transient SOD2 knockdown in embryonic fibroblasts from iSOD2-KD mice also resulted in adaptive mitochondrial changes, enhanced antioxidant capacity, and resistance to a subsequent oxidant challenge. We propose that mitohormesis in response to mitochondrial oxidative stress in mice involves sustained activation of mitochondrial and antioxidant signaling pathways to establish a heightened basal antioxidant state.

Androgen Receptor (AR)-dependent transcription is a major driver of prostate tumor cell proliferation. Consequently, it is the target of several antitumor chemotherapeutic agents, including the AR antagonist MDV3100/enzalutamide. Recent studies have shown that a single AR mutation (F876L) converts MDV3100 action from an antagonist to an agonist. Here we describe the generation of a novel class of Selective Androgen Receptor Degraders (SARDs) to address this resistance mechanism. Molecules containing hydrophobic degrons linked to small molecule Androgen Receptor (AR) ligands induce AR degradation, reduce expression of AR target genes and inhibit proliferation in androgen-dependent prostate cancer cell lines. These results suggest that selective AR degradation may be an effective therapeutic prostate tumor strategy in the context of AR mutations that confer resistance to third generation AR antagonists. KeywordsAntiproliferation; cancer; drug design; hormones; protein degradation Targeted degradation represents an intriguing strategy to regulate the function of therapeutically relevant proteins (e.g., transcription factors and scaffolding proteins) not amenable to traditional small molecule approaches [1,2] . Moreover, targeted protein degradation could overcome resistance mechanisms that modulate the activity of small molecule drugs following target engagement. For instance, point mutants conferring agonist activity to antagonists limit efficacy of androgen-receptor (AR) antagonists for treatment of prostate cancer [3] . While deletion of the disease-causing protein offers a direct solution to this problem, strategies for doing so via genome editing or RNAi remain clinically challenging [4,5] . As an alternative, we have developed several approaches for posttranslational targeting of specific proteins to the ubiquitin-proteasome system (UPS) [6][7][8][9] . For instance, we recently reported a strategy for post-translational protein degradation whereby a hydrophobic moiety appended to the surface of a target protein engages the cellular quality control machinery. This 'hydrophobic tag' may mimic a partially denatured protein folding state, leading to degradation by the UPS. We demonstrated the feasibility of this approach by covalently coupling hydrophobic tags to engineered dehalogenase HaloTag-2 [10][11][12] fusion proteins. Recently, a similar approach was applied to degradation of E. coli DHFR by non-covalent appendage of a hydrophobic tag [13] . A key next step in the development of this nascent technology is to degrade clinically relevant target proteins with a small drug-like molecule. To this end, here we show that coupling a hydrophobic tag to an androgen receptor agonist converts it to a potent Selective Androgen Receptor Degrader (SARD) capable of inducing >50% of AR degradation (DC 50 ) at 1 μM. Remarkably, this SARD retained anti-proliferative activity in cell lines resistant to current standard-of-care drugs for castration-resistant prostate cancer (CRPC).The androgen receptor (AR) [14] is a ...

Nepal has a multitiered health system involving the Ministry of Health, nongovernmental organizations, private for profit, and faith-based organizations. There are national, district, and community-level health centers and health workers that come together to deliver services and input information into both the community and national level health information systems. In terms of mental health, there is a very small portion of the budget allocated to mental health and very few mental health interventions and programs. The system has strengths including that the service delivery is put together in an effective manner and there is some mental health integration in primary care and in the health information system. However, there are weaknesses including that there needs to be an increase in the number of health workers and the training given to the workforce to further integrate mental health and there also needs to be more attention brought to mental health overall. Nepal's COVID-19 response highlighted weaknesses within its health system, especially in the context of its essential medicine products. The COVID-19 response from Nepal was especially hindered by a shortage of medical supplies, personal protective equipment, medications, and coronavirus tests.