In Silico Exploration of Novel Tubulin Inhibitors: A Combination of Docking and Molecular Dynamics Simulations, Pharmacophore Modeling, and Virtual Screening

Microtubules play a critical role in mitosis and cell division and are regarded as an excellent target for anticancer therapy. Although microtubule-targeting agents have been widely used in the clinical treatment of different human cancers, their clinical application in cancer therapy is limited by both intrinsic and acquired drug resistance and adverse toxicities. In a previous work, we synthesized compound 9IV-c, ((E)-2-(3,4-dimethoxystyryl)-6,7,8-trimethoxy-N-(3,4,5-trimethoxyphenyl)quinoline-4-amine) that showed potent activity against multiple human tumor cell lines, by targeting spindle formation and/or the microtubule network. Accordingly, in this study, to identify potent tubulin inhibitors, at first, molecular docking and molecular dynamics studies of compound 9IV-c were performed into the colchicine binding site of tubulin; then, a pharmacophore model of the 9IV-c-tubulin complex was generated. The pharmacophore model was then validated by Güner–Henry (GH) scoring methods and receiver operating characteristic (ROC) analysis. The IBScreen database was searched by using this pharmacophore model as a screening query. Finally, five retrieved compounds were selected for molecular docking studies. These efforts identified two compounds (b and c) as potent tubulin inhibitors. Investigation of pharmacokinetic properties of these compounds (b and c) and compound 9IV-c displayed that ligand b has better drug characteristics compared to the other two ligands.

Heterogeneity, Inherent and Acquired Drug Resistance in Patient-Derived Organoids Models of Primary Liver Cancer

To screen for sensitive drugs for recurrent primary liver cancer (PLC) and elucidate the mechanisms underlying inherent and acquired drug resistance, we established a platform of organoids, organoids-derived xenograft (ODX) mouse models, and patient-derived xenograft (PDX) mouse models of primary liver cancer (PLC). Fifty-two organoids were established from 153 PLC patients. Establishing organoids of hepatocellular carcinoma (HCC) displayed a trend toward a higher success rate than establishing PDX (29.0% vs. 23.7%) and took a shorter duration (13.0 ± 4.7 vs. 25.1 ± 5.4 days, P=2.28×10−13) than establishing PDX models. Larger tumor, vascular invasion, and advanced stage were significantly associated with successful establishment of organoids and PDX in HCC. Organoids and ODX recapitulated PLC histopathological features but enriched more aggressive cell types. PLC organoids were mostly resistant to lenvatinib in vitro but sensitive in ODX model, indicating innate immunity plays a role. Acquired sorafenib-resistant HCC organoids were generated via 3–5 months of induction. RNA-sequencing indicated that stemness– and epithelial–mesenchymal transition (EMT)–related gene sets were upregulated, whereas liver development– and liver specific molecule–related gene sets were downregulated, in acquired sorafenib-resistant organoids. Targeting mTOR signaling pathway was effective in treating acquired sorafenib-resistant HCC, possibly via inducing phosphorylated S6 kinase. Genes upregulated in acquired sorafenib-resistant HCC organoids were often associated with unfavorable prognosis. Conclusively, HCC organoids perform better than PDX for drug selection. Acquired sorafenib resistance in organoids promotes HCC aggressiveness via facilitating the stemness, retrodifferentiation, and EMT. Phosphorylated S6 kinase might be predictive for drug resistance in HCC.

Synergistic Antitumor Effect of Andrographolide and Cisplatin Through ROS-Mediated ER Stress and STAT3 Inhibition in Colon Cancer

Colon cancer is one of the most leading death-causing cancers in the world. Cisplatin has been widely used as the first-line treatment of cancer. However, its clinical application is limited by the side effects or acquired drug resistance. Hence, it is of vital clinical significance to develop novel agents that synergize with cisplatin and decrease its side effects. The aim of this study was to investigate whether Andrographolide (AP) synergistically potentiates the anti-tumor effect of cisplatin on colon cancer cells. Here, we found that AP synergizes with cisplatin in exerting anticancer activity in colon cancer cells. Further studies showed that AP potentiates cisplatin-induced endoplasmic reticulum stress and STAT3 inhibition through increasing intracellular ROS. Notably, pre-treatment of NAC, a ROS scavenger, reversed apoptosis induced by combined treatment of AP and cisplatin, while relieving the activation of endoplasmic reticulum stress as well as STAT3 inhibition. These findings indicated that ROS plays a pivotal role in mediating synergistic anticancer effects of AP and cisplatin on colon cancer cells. Overall, this study presents a potential new therapeutic strategy for the treatment of colon cancer.

Genomic and Transcriptomic Underpinnings of Melanoma Genesis, Progression, and Metastasis

Melanoma is a deadly skin cancer with rapidly increasing incidence worldwide. The discovery of the genetic drivers of melanomagenesis in the last decade has led the World Health Organization to reclassify melanoma subtypes by their molecular pathways rather than traditional clinical and histopathologic features. Despite this significant advance, the genomic and transcriptomic drivers of metastatic progression are less well characterized. This review describes the known molecular pathways of cutaneous and uveal melanoma progression, highlights recently identified pathways and mediators of metastasis, and touches on the influence of the tumor microenvironment on metastatic progression and treatment resistance. While targeted therapies and immune checkpoint blockade have significantly aided in the treatment of advanced disease, acquired drug resistance remains an unfortunately common problem, and there is still a great need to identify potential prognostic markers and novel therapeutic targets to aid in such cases.

Long-term non-invasive drug treatments for adult zebrafish

Zebrafish embryos are widely used for drug-discovery however administering drugs to adult zebrafish is limited by current protocols that can cause stress. Here, we develop a drug formulation and administration method for adult zebrafish by producing food-based drug pellets which are consumed voluntarily. We apply this to zebrafish with BRAF-mutant melanoma, a model that has significantly advanced our understanding of melanoma progression, but not of drug resistance due to the limitations of current treatment methods. Short-term, precise, and daily dosing with drug-pellets made with the BRAFV600E inhibitor, vemurafenib, led to tumour regression. On-target drug efficacy was determined by phospho-ERK staining. Continued drug treatment led to the emergence, for the first time in zebrafish, of acquired drug resistance and melanoma relapse, modelling the responses seen in melanoma patients. This method presents a controlled, non-invasive approach that permits long-term drug studies, and can be widely applied to any adult zebrafish model.

Acquired Drug Resistance Enhances Imidazoquinoline Efflux by P-Glycoprotein

Multidrug-Resistant (MDR) cancers attenuate chemotherapeutic efficacy through drug efflux, a process that transports drugs from within a cell to the extracellular space via ABC (ATP-Binding Cassette) transporters, including P-glycoprotein 1 (P-gp or ABCB1/MDR1). Conversely, Toll-Like Receptor (TLR) agonist immunotherapies modulate activity of tumor-infiltrating immune cells in local proximity to cancer cells and could, therefore, benefit from the enhanced drug efflux in MDR cancers. However, the effect of acquired drug resistance on TLR agonist efflux is largely unknown. We begin to address this by investigating P-gp mediated efflux of TLR 7/8 agonists. First, we used functionalized liposomes to determine that imidazoquinoline TLR agonists Imiquimod, Resiquimod, and Gardiquimod are substrates for P-gp. Interestingly, the least potent imidazoquinoline (Imiquimod) was the best P-gp substrate. Next, we compared imidazoquinoline efflux in MDR cancer cell lines with enhanced P-gp expression relative to parent cancer cell lines. Using P-gp competitive substrates and inhibitors, we observed that imidazoquinoline efflux occurs through P-gp and, for Imiquimod, is enhanced as a consequence of acquired drug resistance. This suggests that enhancing efflux susceptibility could be an important consideration in the rational design of next generation immunotherapies that modulate activity of tumor-infiltrating immune cells.

AXL Knock-Out in SNU475 Hepatocellular Carcinoma Cells Provides Evidence for Lethal Effect Associated with G2 Arrest and Polyploidization

AXL, a member of the TAM family, is a promising therapeutic target due to its elevated expression in advanced hepatocellular carcinoma (HCC), particularly in association with acquired drug resistance. Previously, RNA interference was used to study its role in cancer, and several phenotypic changes, including attenuated cell proliferation and decreased migration and invasion, have been reported. The mechanism of action of AXL in HCC is elusive. We first studied the AXL expression in HCC cell lines by real-time PCR and western blot and showed its stringent association with a mesenchymal phenotype. We then explored the role of AXL in mesenchymal SNU475 cells by CRISPR-Cas9 mediated gene knock-out. AXL-depleted HCC cells displayed drastic phenotypic changes, including increased DNA damage response, prolongation of doubling time, G2 arrest, and polyploidization in vitro and loss of tumorigenicity in vivo. Pharmacological inhibition of AXL by R428 recapitulated G2 arrest and polyploidy phenotype. These observations strongly suggest that acute loss of AXL in some mesenchymal HCC cells is lethal and points out that its inhibition may represent a druggable vulnerability in AXL-high HCC patients.

Research Progress of Carrier-Free Antitumor Nanoparticles Based on Phytochemicals

Cancer is a major worldwide public health issue, responsible for millions of deaths every year. Cancer cases and deaths are expected to increase rapidly with population growth, age, and lifestyle behaviors that increase cancer risk. Long-term chemotherapy results in acquired drug resistance. Traditional treatment methods have limitations and cannot effectively treat distal metastatic cancers. Application of nanocarriers in multi-chemotherapy must be promoted. With research progress, the shortcomings of traditional nanocarriers have gradually become evident. Carrier-free nanodrugs with desirable bioactivity have attracted considerable attention. In this review, we provide an overview of recent reports on several carrier-free nanodrug delivery systems based on phytochemicals. This review focuses on the advantages of carrier-free nanodrugs, and provides new insights for establishment of ideal cancer treatment nanosystems.