Development of the phenylpyrazolo[3,4-d]pyrimidine-based, insulin-like growth factor receptor/Src/AXL-targeting small molecule kinase inhibitor.

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 KrasG12D/+ -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 KrasG12D/+ 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.

Development of a 4-aminopyrazolo[3,4-d]pyrimidine-based dual IGF1R/Src inhibitor as a novel anticancer agent with minimal toxicity.

BACKGROUND: Both the type I insulin-like growth factor receptor (IGF1R) and Src pathways are associated with the development and progression of numerous types of human cancer, and Src activation confers resistance to anti-IGF1R therapies. Hence, targeting both IGF1R and Src concurrently is one of the main challenges in combating resistance to the currently available anti-IGF1R-based anticancer therapies. However, the enhanced toxicity from this combinatorial treatment could be one of the main hurdles for this strategy, suggesting the necessity of developing a novel strategy for co-targeting IGF1R and Src to meet an urgent clinical need. METHODS: We synthesized a series of 4-aminopyrazolo[3,4-d]pyrimidine-based dual IGF1R/Src inhibitors, selected LL28 as an active compound and evaluated its potential antitumor effects in vitro and in vivo using the MTT assay, colony formation assays, flow cytometric analysis, a tumor xenograft model, and the Kras G12D/+ -driven spontaneous lung tumorigenesis model. RESULTS: LL28 markedly suppressed the activation of IGF1R and Src and significantly inhibited the viability of several NSCLC cell lines in vitro by inducing apoptosis. Administration of mice with LL28 significantly suppressed the growth of H1299 NSCLC xenograft tumors without overt toxicity and substantially reduced the multiplicity, volume, and load of lung tumors in the Kras G12D/+ -driven lung tumorigenesis model. CONCLUSIONS: The present results suggest the potential of LL28 as a novel anticancer drug candidate targeting both IGF1R and Src, providing a new avenue to efficient anticancer therapies. Further investigation is warranted in advanced preclinical and clinical settings.

Mitochondria-targeting indolizino[3,2-c]quinolines as novel class of photosensitizers for photodynamic anticancer activity.

To achieve efficient photodynamic activity, substantial effort has been dedicated to precise control of the intracellular localization of current photosensitizers (PSs). Given the extremely small radius of action of singlet oxygen, the direct targeting of PSs to the mitochondria is expected to greatly enhance the photodynamic therapy (PDT) activity. Here, we report mitochondria-targeting 6-(furan-2-yl)- and 6-(thiophen-2-yl) indolizino[3,2-c]quinolines (IQs) as novel PSs. IQ derivatives containing 5-membered heterocyclic aromatic rings were synthesized, and their photophysical properties as PSs were characterized. The anticancer potentials of 2a-2f were investigated using various cancer cell lines, and they exhibited dose-dependent and light exposure time-dependent cytotoxicity. Among the synthesized compounds, 2b, which contains a furan ring, showed dual functions as an imaging probe as well as a PS. Real-time confocal fluorescence images revealed the mitochondrial localization of 2b as a primary site of photodamage in live cells. Targeted reactive oxygen species (ROS)-generation capabilities and the photoinduced DNA cleavage of IQs led to mitochondrial dysfunction and photoinduced apoptosis via the intrinsic pathway. 3D RI tomograms of individual live HeLa cells treated with 2b showed that the progress of photoinduced apoptosis was affected by the PS concentration and light irradiation time. The studied IQs (2b, 2d, and 2e) are expected to serve as a new class of heavy-atom-free PSs with low molecular weights less than 350.