Dasatinib inhibits proliferation of liver cancer cells, but activation of Akt/mTOR compromises dasatinib as a cancer drug.

Dasatinib is a multi-target protein tyrosine kinase inhibitor. Due to its potent inhibition of Src, Abl, the platelet-derived growth factor receptor (PDGFR) family kinases, and other oncogenic kinases, it has been investigated as a targeted therapy for a broad spectrum of cancer types. However, its efficacy has not been significantly extended beyond leukemia. The mechanism of resistance to dasatinib in a wide array of cancers is not clear. In the present study, we investigated the effect of dasatinib on hepatocellular carcinoma cell growth and explored the underlying mechanisms. Our results showed that dasatinib potently inhibited the proliferation of SNU-449 cells, but not that of other cell lines, such as SK-Hep-1, even though it inhibited the phosphorylation of Src on both negative and positive regulation sites in all these cells. Dasatinib activated the phosphoinositide-dependent protein kinase1 (PDK1)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway in SK-Hep-1 cells, but not in SNU-449 cells. Blocking the Akt/mTOR signaling pathway strongly promoted the efficacy of dasatinib in SK-Hep-1 cells. In SNU-449 cells, dasatinib promoted apoptosis and the cleavage of caspase-3 and caspase-7, induced cell cycle arrest in the G1 phase, and inhibited the expression of Cyclin-dependent kinase (CDK4)/6/CyclinD1 complex. These findings demonstrate that dasatinib exerts its anti-proliferative effect on hepatocellular cell proliferation by blocking the Src family kinases; however, it causes Akt activation, which compromises dasatinib as an anti-cancer drug.

Golgi membrane protein GP73 modified-liposome mediates the antitumor effect of survivin promoter-driven HSVtk in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common types of cancer worldwide, and there is currently no effective therapeutic strategy in clinical practice. Gene therapy has great potential for decreasing tumor-induced mortality but has been clinically limited because of the lack of tumor-specific targets and insufficient gene transfer. The study of targeted transport of therapeutic genes in HCC treatment seems to be very important. In this study, we evaluated a gene therapy approach targeting HCC using the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide gene system in HCC cell lines and in an in vivo human HCC xenograft mouse model. GP73-modified liposomes targeted gene delivery to the tumor tissue, and the survivin promoter drove HSVtk expression in the HCC cells. Our results showed that the survivin promoter was specifically activated in tumor cells and HSVtk was expressed selectively in tumor cells. Combined with GCV treatment, HSVtk expression resulted in suppression of HCC cell proliferation via enhancing apoptosis. Moreover, tail vein injection of GP73-HSVtk significantly suppressed the growth of xenograft tumors through an apoptosis-dependent pathway and extended the survival of tumor-bearing mice without damaging the mice liver functions. Taken together, this study demonstrates an effective cancer-specific gene therapy strategy using the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide gene system for HCC that can be further developed for future clinical trials.

Ponatinib Inhibits Proliferation and Induces Apoptosis of Liver Cancer Cells, but Its Efficacy Is Compromised by Its Activation on PDK1/Akt/mTOR Signaling.

Ponatinib is a multi-target protein tyrosine kinase inhibitor, and its effects on hepatocellular carcinoma cells have not been previously explored. In the present study, we investigated its effects on hepatocellular carcinoma cell growth and the underlying mechanisms. Toward SK-Hep-1 and SNU-423 cells, ponatinib induces apoptosis by upregulation of cleaved caspase-3 and -7 and promotes cell cycle arrest in the G1 phase by inhibiting CDK4/6/CyclinD1 complex and phosphorylation of retinoblastoma protein. It inhibits the growth-stimulating mitogen-activated protein (MAP) kinase pathway, the phosphorylation of Src on both negative and positive regulation sites, and Jak2 and Stat3 phosphorylation. Surprisingly, it also activates the PDK1, the protein kinase B (Akt), and the mechanistic target of rapamycin (mTOR) signaling pathway. Blocking mTOR signaling strongly sensitizes cells to inhibition by ponatinib and makes ponatinib a much more potent inhibitor of hepatocellular carcinoma cell proliferation. These findings demonstrate that ponatinib exerts both positive and negative effects on hepatocellular cell proliferation, and eliminating its growth-stimulating effects by drug combination or potentially by chemical medication can significantly improve its efficacy as an anti-cancer drug.

[Ponatinib inhibits the proliferation of SNU-449 human hepatocellular cancer cells and blocks MAPK and PDK1/AKT/mTOR signaling pathways].

Objective To investigate the effects of ponatinib (a multi-target kinase inhibitor) on the proliferation of SNU-449 human hepatocellular cancer cells and the underlying mechanism. Methods SNU-449 hepatocellular cancer cells were treated with 16 tyrosine kinase inhibitors for 72 hours. Then MTT assay was used to detect the effects of ponatinib on the survival and proliferation of the cancer cells. Ponatinib was the most sensitive drug to SNU-449 cells and the IC50 value was obtained. SNU-449 cells were cultured and treated with (0.06, 0.3, 0.6) µmol/L ponatinib, and the control group was treated with DMSO. Colony formation assay and inverted microscope were applied to observe the effects of ponatinib on the colony formation ability and morphology of SNU-449 cells. Flow cytometry was used to detect the effects of ponatinib on the apoptosis and cell cycle of SNU-449 cells. Western blotting was performed to examine the expression of Src, phosphorylated Src (p-Src), mitogen-activated protein kinase kinase (MEK), phosphorylated MEK (p-MEK), extracellular signal-regulated kinase (ERK), phosphorylated ERK (p-ERK), phosphoinositide 3-kinase (PI3K), phosphorylated PI3K (p-PI3K), phosphoinositide-dependent protein kinase 1 (PDK1), phosphorylated PDK1 (p-PDK1), AKT, p-AKT, mammalian target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR). Results MTT assay showed that ponatinib displayed the best inhibitory effects on SNU-449 cells in 16 tyrosine kinase inhibitors. Ponatinib promoted cell apoptosis in a concentration-dependent manner and induced cell cycle arrest at the G1 phase in SNU-449 cells. A number of kinase signaling pathways were inhibited by ponatinib, including the Src signaling pathway, MAPK pathway and PDK1/AKT/mTOR pathway. Conclusion Ponatinib can inhibit the proliferation, promote the apoptosis and cell cycle arrest of hepatocellular cancer cells and block MAPK and PDK1/AKT/mTOR signaling pathways, which might be a potential agent for liver cancer treatment.

[Multi-target kinase inhibitor dasatinib inhibits cell proliferation, dissociation and migration via up-regulating E-cadherin expression in SK-Hep-1 human hepatocellular cancer cells].

Objective To investigate the effects of dasatinib (a multi-target kinase inhibitor) on the proliferation, adhesion and migration ability of SK-Hep-1 human hepatocellular cancer cells and the underlying mechanism. Methods SK-Hep-1, Bel-7402, SNU-423, SNU-387 and Huh-7 hepatocellular cancer cells were treated with dasatinib. Then MTT assay was used to detect the effect of dasatinib on the survival and proliferation of cancer cells, and the sensitive cells were obtained. SK-Hep-1 cells were cultured and treated with (0.5, 1, 2) µmol/L dasatinib, and the control group was treated with DMSO. Slow aggregation assay and dissociation assay were used to detect the effects of dasatinib on the adhesion ability of SK-Hep-1 cells. Wound healing assay was applied to observe the effect of dasatinib on the migration ability of the cancer cells. Western blotting was performed to detect the effect of dasatinib on the expression of E-cadherin. Results MTT assay showed that the proliferation of the liver cancer cells was obviously inhibited by dasatinib and SK-Hep-1 was the most sensitive cells to dasatinib. Dasatinib promoted the aggregation of SK-Hep-1 cells, inhibited cell dissociation and migration, and up-regulated E-cadherin expression. Conclusion Dasatinib can promote the aggregation and adhesion of SK-Hep-1 cells, and inhibit cell proliferation, dissociation and migration via up-regulating E-cadherin expression.

Chidamide induces apoptosis in DLBCL cells by suppressing the HDACs/STAT3/Bcl­2 pathway.

Diffuse large B­cell lymphoma (DLBCL) is a highly heterogeneous malignant tumor type, and epigenetic modifications such as acetylation or deacetylation serve vital roles in its development. Chidamide, a novel histone deacetylase inhibitor, exerts an anticancer effect against various types of cancer. The present study aimed to evaluate the cellular effect of chidamide on a number of DLBCL cell lines and to investigate its underlying mechanism. The results demonstrated that chidamide induced the death of these cells in a concentration­(0­30 µmol/l) and time­dependent (24­72 h) manner, as determined using the Cell Counting Kit­8 cell viability assay. Moreover, chidamide promoted cellular apoptosis, which was identified via flow cytometry and western blot analysis, with an increase in cleaved caspase­3 expression and a decrease in Bcl­2 expression. Chidamide treatment also decreased the expression level of STAT3 and its phosphorylation, which was accompanied by the downregulation of a class­I histone deacetylase (HDAC) inhibitor, chidamide. Collectively, these data suggested that chidamide can be a potent therapeutic agent to treat DLBCL by inducing the apoptotic death of DLBCL cells by inhibiting the HDACs/STAT3/Bcl­2 pathway.

ApoE-modified liposomes mediate the antitumour effect of survivin promoter-driven HSVtk in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a prevalent malignant tumour with high global morbidity and mortality associated with its multiple aetiologies, poor prognosis, resistance to chemotherapeutic drugs and high rate of recurrence. Here, we evaluated a gene therapy strategy that targets HCC using the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide gene system in HCC cell lines and in an in vivo human HCC xenograft mouse model. Apolipoprotein E (ApoE)-modified liposomes were used for targeted gene delivery to the tumour tissue, and the survivin promoter was used to drive HSVtk expression in HCC cells. Our results showed that the survivin promoter was specifically activated in tumour cells, and HSVtk was expressed selectively in tumour cells. In combination with GCV treatment, HSVtk expression resulted in the inhibition of HCC cell proliferation via enhanced apoptosis. In addition, tail vein injection of ApoE-HSVtk significantly suppressed the growth of xenograft tumours through an apoptosis-dependent pathway and extended the survival time of tumour-bearing mice. In summary, this study illustrates an effective cancer-specific gene therapy strategy for HCC that can be further developed for future clinical trials.

Characteristics of regional myocardial stunning after exercise in gated myocardial SPECT.

BACKGROUND: A number of studies have demonstrated prolonged left ventricular (LV) global dysfunction after exercise-induced ischemia in gated myocardial single photon emission tomography (SPECT) as a manifestation of exercise-induced stunning. This study investigated the residual effects of exercise on postexercise LV regional function and its implications on the detection of stunning in gated SPECT. METHODS AND RESULTS: Fifty-three subjects with known or suspected coronary artery disease and 10 control subjects underwent myocardial SPECT according to a same-day exercise-rest protocol. Both postexercise and resting images were gated and acquired 1 hour after injection of technetium 99m tetrofosmin. The LV global ejection fraction and segmental systolic wall thickening were quantitated with the use of an automatic program. Segmental perfusion was assessed semiquantitatively on summed nongated tomograms. Wall thickening index (WTI), the ratio of systolic wall thickening of a segment to that of a corresponding control segment, was significantly lower after exercise than at rest in the reversible defect (RD) segments (0.66 +/- 0.24 vs 0.78 +/- 0.24; P <.0001). In patients with exercise-induced ischemia, the difference in WTI between rest and after exercise was significantly greater in the RD segments, which represented ischemia, than in the non-RD segments. Postexercise WTIs were not different from the resting values in subjects with no perfusion abnormalities or who had fixed defects (infarction). Significant postexercise dysfunction was present in 44% of the RD segments, compared with 5% of the normal and 3% of the fixed defect segments. Postexercise segmental dysfunction was correlated with the segmental reversibility score, the difference in defect scores between exercise and rest images (n = 82, Spearman rank correlation coefficient = -0.78, P <.0001). Among 19 patients with ischemia, 9 (47%) exhibited concurrent segmental and global dysfunction, but segmental dysfunction persisted in the absence of global dysfunction in 4 additional patients (21%). CONCLUSIONS: Significant postexercise LV regional dysfunction, consistent with the concept of stunning, occurs in the region of severe ischemia. The incidence and magnitude of regional stunning are determined by the severity of ischemia. For the detection of stunning in gated SPECT, LV regional dysfunction may be more sensitive than global dysfunction.