Bis-cyclopropane analog of disorazole C1 is a microtubule-destabilizing agent active in ABCB1-overexpressing human colon cancer cells

Cytotoxic Effects of Darinaparsin, a Novel Organic Arsenical, against Human Leukemia Cells

To explore the molecular mechanisms of action underlying the antileukemia activities of darinaparsin, an organic arsenical approved for the treatment of peripheral T-cell lymphoma in Japan, cytotoxicity of darinaparsin was evaluated in leukemia cell lines NB4, U-937, MOLT-4 and HL-60. Darinaparsin was a more potent cytotoxic than sodium arsenite, and induced apoptosis/necrosis in NB4 and HL-60 cells. In NB4 cells exhibiting the highest susceptibility to darinaparsin, apoptosis induction was accompanied by the activation of caspase-8/-9/-3, a substantial decrease in Bid expression, and was suppressed by Boc-D-FMK, a pancaspase inhibitor, suggesting that darinaparsin triggered a convergence of the extrinsic and intrinsic pathways of apoptosis via Bid truncation. A dramatic increase in the expression level of γH2AX, a DNA damage marker, occurred in parallel with G₂/M arrest. Activation of p53 and the inhibition of cdc25C/cyclin B1/cdc2 were concomitantly observed in treated cells. Downregulation of c-Myc, along with inactivation of E2F1 associated with the activation of Rb, was observed, suggesting the critical roles of p53 and c-Myc in darinaparsin-mediated G₂/M arrest. Trolox, an antioxidative reagent, suppressed the apoptosis induction but failed to correct G₂/M arrest, suggesting that oxidative stress primarily contributed to apoptosis induction. Suppression of Notch1 signaling was also confirmed. Our findings provide novel insights into molecular mechanisms underlying the cytotoxicity of darinaparsin and strong rationale for its new clinical application for patients with different types of cancer.

Hepatocyte Thorns, A Novel Drug-Induced Stress Response in Human and Mouse Liver Spheroids

The in vivo-relevant phenotype of 3D liver spheroids allows for long-term studies of, e.g., novel mechanisms of chronic drug-induced liver toxicity. Using this system, we present a novel drug-induced stress response in human and murine hepatocyte spheroids, wherein long slender filaments form after chronic treatment with four different drugs, of which three are PPARα antagonists. The morphology of the thorns varies between donors and the compounds used. They are mainly composed of diverse protein fibres, which are glycosylated. Their formation is inhibited by treatment with fatty acids or antioxidants. Treatment of mice with GW6471 revealed changes in gene and protein expression, such as those in the spheroids. In addition, similar changes in keratin expression were seen following the treatment of hepatotoxic drugs, including aflatoxin B1, paracetamol, chlorpromazine, cyclosporine, and ketoconazole. We suggest that thorn formation may be indicative of hepatocyte metaplasia in response to toxicity and that more focus should be placed on alterations of ECM-derived protein expression as biomarkers of liver disease and chronic drug-induced hepatotoxicity, changes that can be studied in stable in vivo-like hepatic cell systems, such as the spheroids.

Phase 1 study of safety, pharmacokinetics, and pharmacodynamics of tivantinib in combination with bevacizumab in adult patients with advanced solid tumors

PURPOSE

We investigated the combination of tivantinib, a c-MET tyrosine kinase inhibitor (TKI), and bevacizumab, an anti-VEGF-A antibody.

METHODS

Patients with advanced solid tumors received bevacizumab (10 mg/kg intravenously every 2 weeks) and escalating doses of tivantinib (120-360 mg orally twice daily). In addition to safety and preliminary efficacy, we evaluated pharmacokinetics of tivantinib and its metabolites, as well as pharmacodynamic biomarkers in peripheral blood and skin.

RESULTS

Eleven patients received the combination treatment, which was generally well tolerated. The main dose-limiting toxicity was grade 3 hypertension, which was observed in four patients. Other toxicities included lymphopenia and electrolyte disturbances. No exposure-toxicity relationship was observed for tivantinib or metabolites. No clinical responses were observed. Mean levels of the serum cytokine bFGF increased (p = 0.008) after the bevacizumab-only lead-in and decreased back to baseline (p = 0.047) after addition of tivantinib. Tivantinib reduced levels of both phospho-MET (7/11 patients) and tubulin (4/11 patients) in skin.

CONCLUSIONS

The combination of tivantinib and bevacizumab produced toxicities that were largely consistent with the safety profiles of the individual drugs. The study was terminated prior to establishment of the recommended phase II dose (RP2D) due to concerns regarding the mechanism of tivantinib, as well as lack of clinical efficacy seen in this and other studies. Tivantinib reversed the upregulation of bFGF caused by bevacizumab, which has been considered a potential mechanism of resistance to therapies targeting the VEGF pathway. The findings from this study suggest that the mechanism of action of tivantinib in humans may involve inhibition of both c-MET and tubulin expression.

TRIAL REGISTRATION

NCT01749384 (First posted 12/13/2012).

Iterative sure independent ranking and screening for drug response prediction

Background

Prediction of drug response based on multi-omics data is a crucial task in the research of personalized cancer therapy.

Results

We proposed an iterative sure independent ranking and screening (ISIRS) scheme to select drug response-associated features and applied it to the Cancer Cell Line Encyclopedia (CCLE) dataset. For each drug in CCLE, we incorporated multi-omics data including copy number alterations, mutation and gene expression and selected up to 50 features using ISIRS. Then a linear regression model based on the selected features was exploited to predict the drug response. Cross validation test shows that our prediction accuracies are higher than existing methods for most drugs.

Conclusions

Our study indicates that the features selected by the marginal utility measure, which measures the conditional probability of drug responses given the feature, are helpful for drug response prediction.

Effects of electrical stimulation on cell activity, cell cycle, cell apoptosis and β‑catenin pathway in the injured dorsal root ganglion cell

The present study aimed to investigate the effects of electrical stimulation (ES) on cell activity, cell cycle and apoptosis in injured rat dorsal root ganglion (DRG) cells induced by cyclic mechanical stretching (CMS). The present study also investigated whether the Wnt/β‑catenin pathway is involved in this process. Injury and ES models were established in DRG cells. Then, cell activity was detected using a Cell Counting Kit‑8 and 5‑ethynyl‑2'‑deoxyuridine‑594 cell proliferation assay kit. Cell cycle distribution was detected using a cell cycle detection kit. Apoptosis was detected using an Annexin V‑FITC apoptosis detection kit, and Wnt/β‑catenin pathway‑associated proteins were detected using western blotting. The present study demonstrated that CMS decreased DRG cell activity, increased the number of cells in the S phase, promoted cell apoptosis and inhibited the Wnt/β‑catenin pathway. In addition, ES significantly increased the proliferation activity of DRG cells, increased the number of cells in the G2 phase, decreased the apoptotic rate and activated the Wnt/β‑catenin pathway, ultimately reversing the injury caused by CMS. Following inhibition of the Wnt/β‑catenin signaling pathway using XAV939, the effects of ES were weakened. In conclusion, the present study demonstrated that ES may reverse CMS‑induced injury in DRG cells, and that the Wnt signaling pathway may be involved in this process.

Radix Tetrastigma hemsleyani flavone exhibits antitumor activity in colorectal cancer via Wnt/β-catenin signaling pathway

Background

Radix Tetrastigma hemsleyani flavone (RTHF) is extracted from a traditional Chinese medicinal herb T. hemsleyani, which is conventionally used as a folk medicine for its anti-inflammation activity and antiviral activity. In this study, the effects of RTHF on inhibiting malignant biological properties in colorectal cancer (CRC) were evaluated by conducting both in vitro and in vivo experiments, and the underlying mechanism was investigated.

Materials and methods

Cell Counting Kit-8, colony formation, and flow cytometry assays were performed to evaluate the proliferation of RTHF-treated colon tumor cells. Migration and invasion capacities were also tested by cell wound scratch assay and Transwell invasion assay. Moreover, the antitumor effects of RTHF on azoxymethane/dextran sulfate sodium-induced colitis-related CRC were investigated in C57BL/6 mice. In addition, Western blot and/or quantitative reverse transcription polymerase chain reaction analysis were used to evaluate the expressions of Lgr5, Cyclin D1, c-Myc, and E-cadherin.

Results

These experiments showed that RTHF could decrease the cell growth kinetics and clone-forming capacity. RTHF could also dose dependently induce cell cycle arrest at G0/G1 phase and inhibit epithelial-mesenchymal transition process. Furthermore, downregulation of β-catenin activation and downstream protein expression were detected in CRC cells after being treated with RTHF. RTHF daily gavage suppressed the number and size of CRC in mice and inhibited Lgr5 and Cyclin D1 expressions in tumor tissue.

Conclusion

In conclusion, RTHF treatment inhibits colorectal tumor growth, decreases Wnt/β-catenin pathway activity, and downregulates target genes’ expression.

Reversal of the multidrug resistance of human ileocecal adenocarcinoma cells by acetyl-11-keto-β-boswellic acid via downregulation of P-glycoprotein signals

Multidrug resistance (MDR) represents a clinical obstacle to cancer chemotherapy since it causes cancer recurrence and metastasis. Acetyl-11-keto-β-boswellic acid (AKBA), an active ingredient derived from the plant Boswellia serrata, has been found to inhibit the growth of a wide variety of tumor cells, including glioma, colorectal cancer, leukemia, human melanoma, hepatocellular carcinoma, and prostate cancer cells. However, the actions of AKBA in multidrug-resistant cancer cells have not been fully elucidated. The current study examined the reversal of MDR by AKBA in a human ileocecal adenocarcinoma cell line with vincristine-induced resistance, HCT-8/VCR. A 3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay indicated that cytotoxicity increased drastically and the IC50 of VCR in HCT-8/VCR cells decreased in the presence of AKBA. AKBA had a maximum "fold reversal" of MDR (FR) of 9.19-fold. In addition, HCT-8/VCR cells treated with AKBA and VCR exhibited a higher percentage of apoptotic tumor cells according to flow cytometry. The reversal of MDR by AKBA was evident in an intracellular increase in Rhodamine (Rh123), indicating that the activity of P-glycoprotein (P-gp) was blocked. Furthermore, AKBA inhibited the expression of P-gp and decreased levels of expression of multidrug resistance gene 1 in HCT-8/VCR cells. The current results indicated that AKBA might be a potential agent to reverse MDR in human ileocecal adenocarcinoma.