[Protein tyrosine kinase inhibitors in cancer therapy]

Anlotinib Reverses Multidrug Resistance (MDR) in Osteosarcoma by Inhibiting P-Glycoprotein (PGP1) Function In Vitro and In Vivo

Overexpression of the multidrug resistance (MDR)-related protein P-glycoprotein (PGP1), which actively extrudes chemotherapeutic agents from cells and significantly decreases the efficacy of chemotherapy, is viewed as a major obstacle in osteosarcoma chemotherapy. Anlotinib, a novel tyrosine kinase inhibitor (TKI), has good anti-tumor effects in a variety of solid tumors. However, there are few studies on the mechanism of anlotinib reversing chemotherapy resistance in osteosarcoma. In this study, cellular assays were performed in vitro and in vivo to evaluate the MDR reversal effects of anlotinib on multidrug-resistant osteosarcoma cell lines. Drug efflux and intracellular drug accumulation were measured by flow cytometry. The vanadate-sensitive ATPase activity of PGP1 was measured in the presence of a range of anlotinib concentrations. The protein expression level of ABCB1 was detected by Western blotting and immunofluorescence analysis. Our results showed that anlotinib significantly increased the sensitivity of KHOSR2 and U2OSR2 cells (which overexpress PGP1) to chemotherapeutic agents in vitro and in a KHOSR2 xenograft nude mouse model in vivo. Mechanistically, anlotinib increases the intracellular accumulation of PGP1 substrates by inhibiting the efflux function of PGP1 in multidrug-resistant cell lines. Furthermore, anlotinib stimulated the ATPase activity of PGP1 but affected neither the protein expression level nor the localization of PGP1. In animal studies, anlotinib in combination with doxorubicin (DOX) significantly decreased the tumor growth rate and the tumor size in the KHOSR2 xenograft nude mouse model. Overall, our findings suggest that anlotinib may be useful for circumventing MDR to other conventional antineoplastic drugs.

Novel multiple tyrosine kinase inhibitor ponatinib inhibits bFGF-activated signaling in neuroblastoma cells and suppresses neuroblastoma growth in vivo

Neuroblastoma (NB) is one of the most common pediatric malignancies in children. Abnormal activation of receptor tyrosine kinases contributes to the pathological development of NB. Therefore, targeting tyrosine kinase receptors to cure NB is a promising strategy. Here, we report that a multi-targeted tyrosine kinase inhibitor ponatinib inhibited NB cell proliferation and induced NB cell apoptosis in a dose-dependent manner. In addition, ponatinib suppressed the colony formation ability of NB cells. Mechanistically, ponatinib effectively inhibited the FGFR1-activated signaling pathway. Ponatinib also enhanced the cytotoxic effects of doxorubicin on NB cells. Furthermore, ponatinib demonstrated anti-tumor efficacy in vivo by inhibiting tumor growth in an orthotopic xenograft NB mouse model. In summary, our results showed that ponatinib inhibited NB growth both in vitro and in vivo.

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

SU6668 suppresses proliferation of triple negative breast cancer cells through down-regulating MTDH expression

Background

The multiple tyrosine kinase inhibitors SU6668 have a promising therapeutic effect on the progression of hematological malignancies and some solid tumors. Here, we determined its effect on triple negative breast cancer (TNBC) cells and explored the potential molecular mechanism.

Methods

In this study, MDA-MB-231 cells were treated with SU6668 (15 μM, 30 μM) for 72 h and the change of proliferation was examined by MTT and tablet cloning. DNA ploidy was detected by flow cytometric analysis with PI staining. Double-label immunofluorescence method was used to detect the expression and distribution of MTDH proteins. VEGFR2, HIF-1α, MTDH, E-cadhrein, and SMA expressions were detected by Western bolt assay.

Results

This study showed that SU6668 inhibited the proliferation and induced polyploidization of MDA-MB-231 cells in a dose dependent form. SU6668 exposure increased the distribution of MTDH in cytoplasm and decreased its distribution in nuclei. After the treatment of SU6668, VEGFR2, HIF-1α, MTDH and SMA proteins were down-regulated, while E-cadhrein was up-regulated in MDA-MB-231 cells.

Conclusions

In conclusion, SU6668 exposure maybe induces polyploidization, inhibit EMT and influence the expression of MTDH, which suppresses the proliferation in TNBC cells. MTDH is a key signal protein in downstream of VEGF/HIF-1αpathway in MDA-MB-231 cells, which may be used as the potential target in the treatment of TNBC.