Two structurally-unrelated small molecule chemotypes, represented by compounds PAV-617 and PAV-951, with antiviral activity in cell culture against monkeypox virus (MPXV) and human immunodeficiency virus (HIV) respectively, were studied for anti-cancer efficacy. Each exhibited apparent pan-cancer cytotoxicity, reasonable pharmacokinetics, and non-toxicity in mice at active concentrations. Anti-tumor properties of each compound were validated in mouse xenografts against A549 human lung cancer. The targets of these compounds are unconventional: each binds to a different transient, energy-dependent multi-protein complex containing the protein KAP-1(TRIM28), an allosteric modulator known to broadly regulate mechanisms underlying viral and nonviral disease states including cancer. Treatment with these compounds alters the target multi-protein complexes in a manner consistent with allosteric modulation as their mechanism of action. These compounds appear to remove a block, crucial for cancer survival and progression, on the homeostatic linkage of uncontrolled cellular proliferation to apoptosis. These compounds may provide starting points for development of next-generation non-toxic, cancer therapeutics.

Herpes virus infections are endemic and ubiquitous. While only rarely leading to overt encephalitis, subchronic or latent infections have been associated to a variety of conditions, including Alzheimer's disease (AD). The cellular consequences of herpes virus infection are determined by the host proteins recruited during virus replication and assembly. Identifying such virus-recruited host proteins therefore allows the interrogation fundamental cellular events leading to associated "sporadic" diseases. A host protein-targeted small molecule drug highly active against herpes simplex virus 1 (HSV-1) infection in human brain organoids and cell lines was identified to interact with macrophage migration inhibitory factor (MIF) where it acted by intercalating between MIF units within a trimer, as determined by nuclear magnetic resonance (NMR). MIF knockout cells showed a decreased viral antigen/titer ratio corroborating its role in virus assembly. From post-mortem brain homogenates of patients with Braak 6-staged AD the small molecule lead compound specifically eluted a MIF subpopulation that correlated with the oxidized conformer of MIF (oxMIF). HSV-1 led to an increase in tau phosphorylation at distinct residues, and the lead compound decreased tau phosphorylation in recombinant cell lines expressing mutant tau and in neuron-differentiated iPSCs also in the absence of HSV-1 infection. We conclude that MIF is a cellular host factor involved in HSV-1 replication and a drug target with antiviral efficacy. At the same time, MIF also plays a role in tau phosphorylation and is enriched in an oxidized conformation in brains of AD patients. MIF thus presents as a molecular link connecting HSV-1 infection and cellular pathology characteristic of neurodegenerative diseases involving aberrant tau phosphorylation.

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease with a complex, multifactorial pathophysiology, most commonly manifest as loss of motor neurons. We introduce a new mechanism of ALS pathogenesis via a novel drug-like small molecule series that targets protein disulfide isomerase (PDI) within a previously unappreciated transient and energy-dependent multi-protein complex. This novel drug was found to have activity in cellular models for both familial and sporadic ALS, as well as in transgenic worms, flies, and mice bearing a diversity of human genes with ALS-associated mutations. These compounds were initially identified as modulators of human immunodeficiency virus (HIV) capsid assembly in cell-free protein synthesis and assembly (CFPSA) systems, with demonstrated antiviral activity in cell culture. Their advancement as ALS-therapeutics, and the subsequent separation of activity against HIV and ALS in chemical subseries through structure-activity-relationship optimization, may provide insights into the molecular mechanisms governing pathophysiology of disordered homeostasis relevant to ALS.