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Rationale: Cancer stem cells (CSCs) are known to cause tumor recurrence and drug resistance. The heat shock protein (HSP) system plays a major role in preserving expression and function of numerous oncoproteins, including those involved in the CSC activities. We explored novel anticancer drugs, especially those targeting HSP components required for the functional role of CSCs. Methods: Investigation of the role of the HSP system in CSCs and screening of a natural product chemical library were performed by utilizing cancer cell lines, primary cultures of patient-derived xenografts (PDXs), and their putative CSC subpopulations (i.e., those grown under sphere-forming conditions, stably transfected with reporter vectors carrying NANOG or POUSF1 promoters, or carrying high ALDH activity) in vitro and PDX and Kras G12D/+ -driven tumor models in vivo. Regulation of the HSP system was investigated by immunoprecipitation, drug affinity responsive target stability assay, binding experiments using ATP-agarose beads and biotinylated drug, and docking analysis. Results: The HSP system was activated in CSCs via transcriptional upregulation of the HSP system components, especially HSP70. Evodiamine (Evo) was identified to induce apoptosis in both CSC and bulk non-CSC populations in human lung, colon, and breast cancer cells and their sublines with chemoresistance. Evo administration decreased the multiplicity, volume, and load of lung tumors in Kras G12D/+ transgenic mice and the growth of cancer cell line- and PDX-derived tumors without detectable toxicity. Mechanistically, Evo disrupted the HSP system by binding the N-terminal ATP-binding pocket of HSP70 and causing its ubiquitin-mediated degradation. Conclusions: Our findings illustrate HSP70 as a potential target for eliminating CSCs and Evo as an effective HSP70-targeting anticancer drug eradicating both CSCs and non-CSCs with a minimal toxicity., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Rationale: The type I insulin-like growth factor receptor (IGF-1R) signaling pathway plays key roles in the development and progression of numerous types of human cancers, and Src and AXL have been found to confer resistance to anti-IGF-1R therapies. Hence, co-targeting Src and AXL may be an effective strategy to overcome resistance to anti-IGF-1R therapies. However, pharmacologic targeting of these three kinases may result in enhanced toxicity. Therefore, the development of novel multitarget anticancer drugs that block IGF-1R, Src, and AXL is urgently needed. Methods: We synthesized a series of phenylpyrazolo[3,4- d ]pyrimidine (PP)-based compounds, wherein the PP module was conjugated with 2,4-bis-arylamino-1,3-pyrimidines (I2) via a copper(I)-catalyzed alkyne-azide cycloaddition reaction. To develop IGF-1R/Src/AXL-targeting small molecule kinase inhibitors, we selected LL6 as an active compound and evaluated its antitumor and antimetastatic effects in vitro and in vivo using the MTT assay, colony formation assays, migration assay, flow cytometric analysis, a tumor xenograft model, the Kras G12D/+ -driven spontaneous lung tumorigenesis model, and a spontaneous metastasis model using Lewis lung carcinoma (LLC) allografts. We also determined the toxicity of LL6 in vitro and in vivo . Results: LL6 induced apoptosis and suppressed viability and colony-forming capacities of various non-small cell lung cancer (NSCLC) cell lines and their sublines with drug resistance. LL6 also suppressed the migration of NSCLC cells at nontoxic doses. Administration of LL6 in mice significantly suppressed the growth of NSCLC xenograft tumors and metastasis of LLC allograft tumors with outstanding toxicity profiles. Furthermore, the multiplicity, volume, and load of lung tumors in Kras G12D/+ transgenic mice were substantially reduced by the LL6 treatment. Conclusions: Our results show the potential of LL6 as a novel IGF-1R/Src/AXL-targeting small molecule kinase inhibitor, providing a new avenue for anticancer therapies., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Introduction: Tyrosine kinase inhibitors (TKIs) improve the survival rate of patients with chronic myeloid leukemia (CML). However, elderly patients often experience adverse events and require dose adjustments, leading to dose interruptions or treatment discontinuation. We therefore investigated TKI dosing patterns and subsequent outcomes in elderly CML patients., Patients and Methods: Using the National Health Information Database, we identified patients with CML aged ≥ 70 years who were prescribed TKIs (imatinib, dasatinib, nilotinib, or radotinib) during 2007-2013. Data on age, sex, prescribed medication, and date of death were extracted., Results: Among the 378 patients, the median age was 75 (range, 70-92) years; the median follow-up period was 53 (range, 1-133) months. Imatinib, dasatinib, nilotinib, and radotinib were prescribed to 324 (85.7%), 110 (29.1%), 93 (24.6%), and 15 (4.0%) patients, respectively. In 42 patients (12.2%), the initial dose was lower than the recommended dose for chronic-phase CML. At last follow-up, 249 patients (65.9%) were receiving a reduced dose. The mean ± standard deviation dose densities of imatinib, dasatinib, nilotinib, and radotinib were 207 ± 121.6, 29 ± 26.7, 235 ± 197, and 123 ± 95.4 mg/day, respectively. The estimated 5-year overall survival probability was 61.0%. Initial TKI dose or dose reduction within first year did not affect the overall survival (P = .0571 and .1826, respectively)., Conclusion: Dose reduction was observed in 65.9% of the patients at their last visit; except for imatinib, TKI dose densities were < 50% of the recommended dose for the chronic phase. Therefore, the recommended TKI doses might be too high for elderly patients with CML., (Copyright © 2019. Published by Elsevier Inc.)

Despite the development of advanced therapeutic regimens such as molecular targeted therapy and immunotherapy, the 5-year survival of patients with lung cancer is still less than 20%, suggesting the need to develop additional treatment strategies. The molecular chaperone heat shock protein 90 (Hsp90) plays important roles in the maturation of oncogenic proteins and thus has been considered as an anticancer therapeutic target. Here we show the efficacy and biological mechanism of a Hsp90 inhibitor NCT-50, a novobiocin-deguelin analog hybridizing the pharmacophores of these known Hsp90 inhibitors. NCT-50 exhibited significant inhibitory effects on the viability and colony formation of non-small cell lung cancer (NSCLC) cells and those carrying resistance to chemotherapy. In contrast, NCT-50 showed minimal effects on the viability of normal cells. NCT-50 induced apoptosis in NSCLC cells, inhibited the expression and activity of several Hsp90 clients including hypoxia-inducible factor (HIF)-1α, and suppressed pro-angiogenic effects of NSCLC cells. Further biochemical and in silico studies revealed that NCT-50 downregulated Hsp90 function by interacting with the C-terminal ATP-binding pocket of Hsp90, leading to decrease in the interaction with Hsp90 client proteins. These results suggest the potential of NCT-50 as an anticancer Hsp90 inhibitor.

Histone deacetylase (HDAC) inhibitors (HDIs) are promising anticancer therapies and have been clinically used for the treatment of hematological malignancy. However, their efficacy in solid tumors is marginal and drug resistance hampers their further clinical utility. To develop novel strategies for the HDI-based anticancer therapeutics in non-small cell lung cancer (NSCLC), in the present study, we investigated the mechanisms underlying resistance to HDI treatment in NSCLC cells. We show the STAT3-mediated IGF2/IGF-1R signaling cascade as a key modulator for both acquired and primary HDI resistance. The treatment with HDI upregulated IGF2 transcription in NSCLC cells carrying intrinsic or acquired drug resistance via direct binding of STAT3 in IGF2 P3 and P4 promoters. Acetylated STAT3 emerged upon HDAC inhibition was protected from the proteasome-mediated degradation of STAT3 and functioned as a direct transcription factor for IGF2 expression. Genomic or pharmacological strategies targeting STAT3 diminished the HDI-induced IGF2 mRNA expression and overcame the resistance to HDI treatment in HDI-resistant NSCLC- or patient-derived tumor xenograft models. These findings provide new insights into the role of acetylated STAT3-mediated activation of IGF2 transcription in HDI resistance, suggesting IGF2 or STAT3 as novel targets to overcome HDI resistance in NSCLC.

The Hsp90 facilitates proper folding of signaling proteins associated with cancer progression, gaining attention as a target for therapeutic intervention. The natural rotenoid deguelin was identified as an Hsp90 inhibitor, but concerns about neurotoxicity have limited prospects for clinical development. In this study, we report progress on deguelin analogues that address this limitation, focusing on the novel analogue SH-1242 as a candidate to broadly target human lung cancer cells, including those that are chemoresistant or harboring KRAS mutations. In a KRAS-driven mouse model of lung cancer, SH-1242 administration reduced tumor multiplicity, volume, and load. Similarly, in human cell line-based or patient-derived tumor xenograft models, SH-1242 induced apoptosis and reduced tumor vasculature in the absence of detectable toxicity. In contrast to deguelin, SH-1242 toxicity was greatly reduced in normal cells and when administered to rats did not produce obvious histopathologic features in the brain. Mechanistic studies revealed that SH-1242 bound to the C-terminal ATP-binding pocket of Hsp90, disrupting the ability to interact with its co-chaperones and clients and triggering a degradation of client proteins without affecting Hsp70 expression. Taken together, our findings illustrate the superior properties of SH-1242 as an Hsp90 inhibitor and as an effective antitumor and minimally toxic agent, providing a foundation for advancing further preclinical and clinical studies., (©2015 American Association for Cancer Research.)