Facilitated Drug Repurposing with Artemisinin-Derived PROTACs: Unveiling PCLAF as a Therapeutic Target.

Artemisinin, a prominent anti-malaria drug, is being investigated for its potential as a repurposed cancer treatment. However, its effectiveness in tumor cell lines remains limited, and its mechanism of action is unclear. To make more progress, the PROteolysis-TArgeting chimera (PROTAC) technique has been applied to design and synthesize novel artemisinin derivatives in this study. Among them, AD4, the most potent compound, exhibited an IC50 value of 50.6 nM in RS4;11 cells, over 12-fold better than that of its parent compound, SM1044. This was supported by prolonged survival of RS4;11-transplanted NOD/SCID mice. Meanwhile, AD4 effectively degraded PCLAF in RS4;11 cells and thus activated the p21/Rb axis to exert antitumor activity by directly targeting PCLAF. The discovery of AD4 highlights the great potential of using PROTACs to improve the efficacy of natural products, identify therapeutic targets, and facilitate drug repurposing. This opens a promising avenue for transforming other natural products into effective therapies.

Design, Synthesis, and Biological Evaluation of N14-Amino Acid-Substituted Tetrandrine Derivatives as Potential Antitumor Agents against Human Colorectal Cancer.

As a typical dibenzylisoquinoline alkaloid, tetrandrine (TET) is clinically used for the treatment of silicosis, inflammatory pulmonary, and cardiovascular diseases in China. Recent investigations have demonstrated the outstanding anticancer activity of this structure, but its poor aqueous solubility severely restricts its further development. Herein, a series of its 14-N-amino acid-substituted derivatives with improved anticancer effects and aqueous solubility were designed and synthesized. Among them, compound 16 displayed the best antiproliferative activity against human colorectal cancer (HCT-15) cells, with an IC50 value of 0.57 µM. Compared with TET, 16 was markedly improved in terms of aqueous solubility (by 5-fold). Compound 16 significantly suppressed the colony formation, migration, and invasion of HCT-15 cells in a concentration-dependent manner, with it being more potent in this respect than TET. Additionally, compound 16 markedly impaired the morphology and motility of HCT-15 cells and induced the death of colorectal cancer cells in double-staining and flow cytometry assays. Western blot results revealed that 16 could induce the autophagy of HCT-15 cells by significantly decreasing the content of p62/SQSTM1 and enhancing the Beclin-1 level and the ratio of LC3-II to LC3-I. Further study showed that 16 effectively inhibited the proliferation, migration, and tube formation of umbilical vein endothelial cells, manifesting in a potent anti-angiogenesis effect. Overall, these results revealed the potential of 16 as a promising candidate for further preclinical studies.

Design, synthesis, and biological evaluation of 2,4-diamino pyrimidine derivatives as potent FAK inhibitors with anti-cancer and anti-angiogenesis activities.

A series of 2,4-diamino pyrimidine (DAPY) derivatives were designed, synthesized, and evaluated as inhibitors of focal adhesion kinase (FAK) with antitumor and anti-angiogenesis activities. Most compounds effectively suppressed the enzymatic activities of FAK, and the IC50s of 11b and 12f were 2.75 and 1.87 nM, respectively. 11b and 12f exhibited strong antiproliferative effects against seven human cancer cells, with IC50 values against two FAK-overexpressing pancreatic cancer cells (PANC-1 and BxPC-3) of 0.98 µM, 0.55 µM, and 0.11 µM, 0.15 µM, respectively. Moreover, 11b and 12f obviously suppressed the colony formation, migration, and invasion of PANC-1 cells in a dose-dependent manner. Meanwhile, these two compounds could induce the apoptosis of PANC-1 cells and arrest the cell cycle in G2/M phase according to the flow cytometry assay. Western blot revealed that 11b and 12f effectively inhibited the FAK/PI3K/Akt signal pathway and significantly decreased the expression of cyclin D1 and Bcl-2. In addition, compounds 11b and 12f potently inhibited the antiproliferative of HUVECs and obviously altered the cell morphology. 11b and 12f also significantly inhibited the migration, tube formation of HUVECs and severely impaired the angiogenesis in the zebrafish model. Overall, these results revealed the potential of compounds 11b and 12f as promising candidates for further preclinical studies.

Discovery of tetrandrine derivatives as tumor migration, invasion and angiogenesis inhibitors.

Metastatic progression of cancer is a complex and clinically daunting process, with migration, invasion and angiogenesis being the key features. Tetrandrine (TET) is a typical dibenzylisoquinoline alkaloid with promising anti-tumor activity. In our previous work, a number of TET derivatives were designed and synthesized with obvious anti-proliferation activities against cancer cells, however, the anti-metastatic effects of these compounds were not evaluated. In the current investigation, five TET derivatives (8, 18, 32, 71, and 72) with pronounced anti-proliferative activities (IC50 values of 1.00, 1.91, 3.43, 3.78, and 1.93 µM, respectively) against human umbilical vein endothelial cells (HUVECs) were screened out. Scratch assays showed that these compounds significantly suppressed the migration of HUVECs and induced their apoptosis. Among them, derivatives 8 and 72 obviously inhibited the proliferation, colony formation and invasion of HCT-15 cells. Tube formation assays revealed that 4 µM of 8 or 72 remarkably inhibited the tube forming capacity of HUVECs. Moreover, 8 and 72 surpressed the formation of filopodia in HUVECs and severely impaired their motility. Both compounds effectively inhibited the angiogenesis in the zebrafish model with low toxicities in vivo. These results indicated that TET derivatives 8 and 72 are promising anti-metastatic inhibitors.

Design, synthesis, and cytotoxic activity of novel 7-substituted camptothecin derivatives incorporating piperazinyl-sulfonylamidine moieties.

In our continuing search for camptothecin (CPT)-derived antitumor drugs, novel 7-substituted CPT derivatives incorporating piperazinyl-sulfonylamidine moieties were designed, synthesized and evaluated for cytotoxicity against five tumor cell lines (A-549, MDA-MB-231, MCF-7, KB, and KB-VIN). All of the derivatives showed promising in vitro cytotoxic activity against the tested tumor cell lines, and were more potent than irinotecan. Remarkably, most of the compounds exhibited comparable cytotoxicity against the multidrug-resistant (MDR) KB-VIN and parental KB tumor cell lines, while irinotecan lost activity completely against KB-VIN. Especially, compounds 13r and 13p (IC50 0.38 and 0.85µM, respectively) displayed the greatest cytotoxicity against the MDR KB-VIN cell line and merit further development into preclinical and clinical drug candidates for treating cancer, including MDR phenotype.

Design, synthesis, cytotoxic activity and molecular docking studies of new 20(S)-sulfonylamidine camptothecin derivatives.

In an ongoing investigation of 20-sulfonylamidine derivatives (9, YQL-9a) of camptothecin (1) as potential anticancer agents directly and selectively inhibiting topoisomerase (Topo) I, the sulfonylamidine pharmacophore was held constant, and a camptothecin derivatives with various substitution patterns were synthesized. The new compounds were evaluated for antiproliferative activity against three human tumor cell lines, A-549, KB, and multidrug resistant (MDR) KB subline (KBvin). Several analogs showed comparable or superior antiproliferative activity compared to the clinically prescribed 1 and irinotecan (3). Significantly, the 20-sulfonylamidine derivatives exhibited comparable cytotoxicity against KBvin, while 1 and 3 were less active against this cell line. Among them, compound 15c displayed much better cytotoxic activity than the controls 1, 3, and 9. Novel key structural features related to the antiproliferative activities were identified by structure-activity relationship (SAR) analysis. In a molecular docking model, compounds 9 and 15c interacted with Topo I-DNA through a different binding mode from 1 and 3. The sulfonylamidine side chains of 9 and 15c could likely form direct hydrogen bonds with Topo I, while hydrophobic interaction with Topo I and π-π stacking with double strand DNA were also confirmed as binding driving forces. The results from docking models were consistent with the SAR conclusions. The introduction of bulky substituents at the 20-position contributed to the altered binding mode of the compound by allowing them to form new interactions with Topo I residues. The information obtained in this study will be helpful for the design of new derivatives of 1 with most promising anticancer activity.

Design, synthesis, mechanisms of action, and toxicity of novel 20(s)-sulfonylamidine derivatives of camptothecin as potent antitumor agents.

Twelve novel 20-sulfonylamidine derivatives (9a-9l) of camptothecin (1) were synthesized via a Cu-catalyzed three-component reaction. They showed similar or superior cytotoxicity compared with that of irinotecan (3) against A-549, DU-145, KB, and multidrug-resistant (MDR) KBvin tumor cell lines. Compound 9a demonstrated better cytotoxicity against MDR cells compared with that of 1 and 3. Mechanistically, 9a induced significant DNA damage by selectively inhibiting Topoisomerase (Topo) I and activating the ATM/Chk related DNA damage-response pathway. In xenograft models, 9a demonstrated significant activity without overt adverse effects at 5 and 10 mg/kg, comparable to 3 at 100 mg/kg. Notably, 9a at 300 mg/kg (i.p.) showed no overt toxicity in contrast to 1 (LD50 56.2 mg/kg, i.p.) and 3 (LD50 177.5 mg/kg, i.p.). Intact 9a inhibited Topo I activity in a cell-free assay in a manner similar to that of 1, confirming that 9a is a new class of Topo I inhibitor. 20-Sulfonylamidine 1-derivative 9a merits development as an anticancer clinical trial candidate.