Inhibition of SIRT3 exhibited potency in triggering leukemic cell differentiation. In discovery of potent SIRT3 inhibitors for cancer differentiation therapy, structural modification was performed on the previously developed lead compound P6. A total of 33 compounds were designed and synthesized. In the enzyme inhibitory assay, several molecules S18, S26, S27 and T5 showed potent SIRT3 inhibitory activity with IC50 value of 0.53, 1.86, 5.06, and 2.88 μM, respectively. Moreover, the tested compounds exhibited SIRT3 inhibitory selectivity over SIRT1 and SIRT2. Compounds S27 and T5 were potent in inhibition the growth of MM1.S and RPMI-8226 cells in the in vitro antiproliferative test. Significantly, representative compounds, especially S27 and T5, promoted differentiation of tested MM cells in the cellular morphological evaluation, accompanied by increasing the expression of differentiation antigen CD49e and human immunoglobulin light chain lambda and kappa. Additionally, molecule S18 without antiproliferative potency itself, showed significant inhibitory activity against growth factor IL-6 induced RPMI-8226 cell proliferation. Collectively, potent SIRT3 selective inhibitors with MM cell differentiation potency were developed for further discovery of anticancer drugs.

The goal of this work was to develop a sensitive and accurate method based on high performance liquid chro-matography with tandem mass spectrometry (LC-MS) detection for determining the concentration of the Sino-menine derivative SWX in plasma and tissue of rat. Chromatographic separation was achieved on an Agilent SB-C18 (2.1*50 mm, 2.7 mu m) column. The mobile phase consisted of acetonitrile (solvent A) and 0.2 % formic acid in water (solvent B) with gradient elution as follows: 0-3 min, 50-90 % A, 3 min-3.01 min, 90-50 % A, 90 % A in 3.01 min-10 min. The flow rate was set to 0.3 mL/min. The column temperature was 40 degrees C, and the sample injection volume was 10 mu L. The calibration curve had good linearity in the range of 10 ng/mL to 600 ng/mL. Biological samples were prepared by protein precipitation with acetonitrile. The area under the curve (AUC) and the peak drug concentration (Cmax) were linearly related to SWX dose. After oral administration of 25, 50 and 100 mg/kg SWX and intravenous administration of 0.5 mg/kg SWX, respectively, the absolute bioavailability of SWX was estimated as 12.4 %, 12.2 % and 10.6 %. SWX was widely distributed in heart, liver, spleen, lung, kidney, brain, breast, and fat, especially in lung, liver, and spleen. Distribution of SWX in brain suggested that it can pass the blood-brain barrier. The method established in this study has the advantages of high recovery and good reproducibility, and was suitable for the determination of the content of Sinomenine derivatives, providing a reliable scientific tool for carrying out pharmacokinetics research, providing a reliable scientific resource.

Aminopeptidase N(APN/CD13), a Zn2+-dependent ectopeptidase localized on the cell surface, is widely considered to influence the invasion of tumor cells. We found that boroleucine and dino-leucine borate exhibited a strong inhibitory effect on the enzyme activity of aminopeptidase N. The tested assay indicated that both compounds had an anti-proliferative effect on triple-negative breast cancer cells. Wound healing assay, migration test and matrigel-coated transwell assay showed that both boroleucine and dino-leucine borate inhibited the migration and invasion of breast cancer cells. Immunoblot analysis showed that both compounds down-regulated the expression of matrix metalloproteinase-2/9. In the capillary tube formation assay of human umbilical vein endothelial cells (HUVECs), dino-leucine borate showed better antiangiogenic activity than ubenimex even at a low concentration (10 μM). Moreover, compared with ubenimex, the anti-metastatic activity of dino-leucine borate in vivo was similar to or even better than that of ubenimex in the H22 pulmonary metastasis mouse model. In this paper, we found the novel APN inhibitors to markedly suppress the enzyme activity of APN and inhibit the migration and invasion of tumor cells in vitro and in vivo.

Dysregulation or aberrant signaling transduction contributes to tumorigenesis. Targeting these abnormal signaling pathways becomes an effective anticancer strategy. However, feedback activation or crosstalk between signaling pathways drives adaptive drug resistance which causes failure of cancer therapy. In this review article, we summarized treatments that cause feedback activation of AKT, ERK, STAT3, EGFR, FGFR, and HER2/3 signaling pathways and the combination therapy to enhance anti-tumor effect or to overcome drug resistance, to explore the underlying mechanisms that define the protein molecules participated or regulated the feedback activation. In addition, we reviewed clinical trials that employ combination treatments to suppress feedback activation and improve therapeutic efficacy of cancer treatments.