Identification of Novel ROS Inducers: Quinone Derivatives Tethered to Long Hydrocarbon Chains

We performed the first synthesis of the 17-carbon chain-tethered quinone moiety <b>22</b> (SAN5201) of irisferin A, a natural product exhibiting anticancer activity, and its derivatives. We found that <b>22</b> is a potent ROS inducer and cytotoxic agent. Compound <b>25</b> (SAN7401), the hydroquinone form of <b>22</b>, induced a significant release of intracellular ROS and apoptosis (EC₅₀ = 1.3–2.6 μM) in cancer cell lines, including A549 and HCT-116. Compared with the activity of a well-known ROS inducer, piperlongumine, <b>22</b> and <b>25</b> showed stronger cytotoxicity and higher selectivity over noncancerous cells. Another hydroquinone tethering 12-carbon chain, <b>26</b> (SAN4601), generated reduced levels of ROS but showed more potent cytotoxicity (EC₅₀ = 0.8–1.6 μM) in cancer cells, although it lacked selectivity over noncancerous cells, implying that the naturally occurring 17-carbon chain is also crucial for ROS production and a selective anticancer effect. Both <b>25</b> and <b>26</b> displayed strong, equipotent activities against vemurafenib-resistant SK-Mel2 melanoma cells and p53-deficient H1299 lung cancer cells as well, demonstrating their broad therapeutic potential as anticancer agents

Discovery of 3-((3-amino-<i>1H</i>-indazol-4-yl)ethynyl)-<i>N</i>-(4-((4-ethylpiperazin-1-yl)methyl)-3-(trifluoromethyl)phenyl)benzamide (AKE-72), a potent Pan-BCR-ABL inhibitor including the T315I gatekeeper resistant mutant

BCR-ABL inhibition is an effective therapeutic approach for the treatment of chronic myeloid leukaemia (CML). Herein, we report the discovery of AKE-72 (5), a diarylamide 3-aminoindazole, as a potent pan-BCR-ABL inhibitor, including the imatinib-resistant mutant T315I. A focussed array of compounds 4a, 4b, and 5 has been designed based on our previously reported indazole I to improve its BCR-ABLT315I inhibitory activity. Replacing the morpholine moiety of I with the privileged tail (4-ethylpiperazin-1-yl)methyl afforded 5 (AKE-72) with IC50 values of WT and BCR-ABLT315I, respectively. Moreover, AKE-72 potently inhibited a panel of other clinically important mutants in single-digit nanomolar IC50 values. AKE-72 elicited remarkable anti-leukemic activity against K-562 cell line (GI50 AKE-72 strongly inhibited the proliferation of Ba/F3 cells expressing native BCR-ABL or its T315I mutant. Overall, AKE-72 may serve as a promising candidate for the treatment of CML, including those harbouring T315I mutation.</p

Selective ATP-Competitive Inhibitors of TOR Suppress Rapamycin-Insensitive Function of TORC2 in <i>Saccharomyces cerevisiae</i>

The target of rapamycin (TOR) is a critical regulator of growth, survival, and energy metabolism. The allosteric TORC1 inhibitor rapamycin has been used extensively to elucidate the TOR related signal pathway but is limited by its inability to inhibit TORC2. We used an unbiased cell proliferation assay of a kinase inhibitor library to discover QL-IX-55 as a potent inhibitor of S. <i>cerevisiae</i> growth. The functional target of QL-IX-55 is the ATP-binding site of TOR2 as evidenced by the discovery of resistant alleles of TOR2 through rational design and unbiased selection strategies. QL-IX-55 is capable of potently inhibiting both TOR complex 1 and 2 (TORC1 and TORC2) as demonstrated by biochemical IP kinase assays (IC₅₀ <50 nM) and cellular assays for inhibition of substrate YPK1 phosphorylation. In contrast to rapamycin, QL-IX-55 is capable of inhibiting TORC2-dependent transcription, which suggests that this compound will be a powerful probe to dissect the Tor2/TORC2-related signaling pathway in yeast

Selective ATP-Competitive Inhibitors of TOR Suppress Rapamycin-Insensitive Function of TORC2 in <i>Saccharomyces cerevisiae</i>

The target of rapamycin (TOR) is a critical regulator of growth, survival, and energy metabolism. The allosteric TORC1 inhibitor rapamycin has been used extensively to elucidate the TOR related signal pathway but is limited by its inability to inhibit TORC2. We used an unbiased cell proliferation assay of a kinase inhibitor library to discover QL-IX-55 as a potent inhibitor of S. <i>cerevisiae</i> growth. The functional target of QL-IX-55 is the ATP-binding site of TOR2 as evidenced by the discovery of resistant alleles of TOR2 through rational design and unbiased selection strategies. QL-IX-55 is capable of potently inhibiting both TOR complex 1 and 2 (TORC1 and TORC2) as demonstrated by biochemical IP kinase assays (IC₅₀ <50 nM) and cellular assays for inhibition of substrate YPK1 phosphorylation. In contrast to rapamycin, QL-IX-55 is capable of inhibiting TORC2-dependent transcription, which suggests that this compound will be a powerful probe to dissect the Tor2/TORC2-related signaling pathway in yeast

Identification of the First Selective Activin Receptor-Like Kinase 1 Inhibitor, a Reversible Version of L‑783277

We synthesized <b>1</b> (San78-130), a reversible version of L-783277, as a selective and potent ALK1 inhibitor. Our study showed that <b>1</b> possesses great kinase selectivity against a panel of 342 kinases and more potent activity against ALK1 than L-783277. Among the six ALK isotypes (ALK1–6), ALK1 is most significantly inhibited by compound <b>1</b>. Compound <b>1</b> suppresses the BMP9-induced Smad1/5 pathway by mainly inhibiting ALK1 in C2C12 cells. Our molecular dynamics simulations suggest that H-bonding interaction between the C-4′ hydroxyl group of <b>1</b> and Arg334 of ALK1 substantially contributes to the ALK1 inhibition. To the best of our knowledge, <b>1</b> is the first selective ALK1 inhibitor. Furthermore, compound <b>1</b> promoted angiogenesis in both endothelial tube formation and microfluidic chip based 3D angiogenesis assays, suggesting that <b>1</b> could be a lead compound for therapeutic angiogenesis agents. Our study may provide an insight into designing selective and potent inhibitors against ALK1

Discovery of a Selective Irreversible BMX Inhibitor for Prostate Cancer

BMX is a member of the TEC family of nonreceptor tyrosine kinases. We have used structure-based drug design in conjunction with kinome profiling to develop a potent, selective, and irreversible BMX kinase inhibitor, BMX-IN-1, which covalently modifies Cys496. BMX-IN-1 inhibits the proliferation of Tel-BMX-transformed Ba/F3 cells at two digit nanomolar concentrations but requires single digit micromolar concentrations to inhibit the proliferation of prostate cancer cell lines. Using a combinatorial kinase inhibitor screening strategy, we discovered that the allosteric Akt inhibitor, MK2206, is able to potentiate BMX inhibitor’s antiproliferation efficacy against prostate cancer cells