Pei-Yen Yeh

Down-regulation of Phospho-Akt Is a Major Molecular Determinant of Bortezomib-Induced Apoptosis in Hepatocellular Carcinoma Cells

Bortezomib, a proteasome inhibitor, has been clinically approved for the treatment of myeloma and lymphoma. Here, we report a differential effect of bortezomib on apoptosis in four hepatocellular carcinoma (HCC) cell lines and identify the major molecular event that determines sensitivity. Although bortezomib inhibited proteasome activity to a similar extent in all HCC cell lines, it showed differential effects on their viability: Huh-7 (IC(50) 196 nmol/L), Sk-Hep1 (IC(50) 180 nmol/L), Hep3B (IC(50) 112 nmol/L), and resistant PLC5 (IC(50) >1,000 nmol/L). Bortezomib caused cell cycle arrest at G(2)-M phase in all HCC cells tested whereas apoptotic induction was found only in sensitive cells but not in PLC5 cells. No significant bortezomib-induced NF-kappaB changes were noted in Huh-7 and PLC5. Bortezomib down-regulated phospho-Akt (P-Akt) in a dose- and time-dependent manner in all sensitive HCC cells whereas no alterations of P-Akt were found in PLC5. Down-regulation of Akt1 by small interference RNA overcame the apoptotic resistance to bortezomib in PLC5 cells, but a constitutively activated Akt1 protected Huh-7 cells from bortezomib-induced apoptosis. Furthermore, bortezomib showed suppression of tumor growth with down-regulation of P-Akt in Huh-7 tumors but not in PLC5 tumors. Down-regulation of P-Akt represents a major molecular event of bortezomib-induced apoptosis in HCC cell lines and may be a biomarker for predicting clinical response to HCC treatment. Targeting Akt signaling overcomes drug resistance to bortezomib in HCC cells, which provides a new approach for the combinational therapy of HCC.

Bortezomib Overcomes Tumor Necrosis Factor-related Apoptosis-inducing Ligand Resistance in Hepatocellular Carcinoma Cells in Part through the Inhibition of the Phosphatidylinositol 3-Kinase/Akt Pathway

Hepatocellular carcinoma (HCC) is one of the most common and aggressive human malignancies. Recombinant tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anti-tumor agent. However, many HCC cells show resistance to TRAIL-induced apoptosis. In this study, we showed that bortezomib, a proteasome inhibitor, overcame TRAIL resistance in HCC cells, including Huh-7, Hep3B, and Sk-Hep1. The combination of bortezomib and TRAIL restored the sensitivity of HCC cells to TRAIL-induced apoptosis. Comparing the molecular change in HCC cells treated with these agents, we found that down-regulation of phospho-Akt (P-Akt) played a key role in mediating TRAIL sensitization of bortezomib. The first evidence was that bortezomib down-regulated P-Akt in a dose- and time-dependent manner in TRAIL-treated HCC cells. Second, LY294002, a PI3K inhibitor, also sensitized resistant HCC cells to TRAIL-induced apoptosis. Third, knocking down Akt1 by small interference RNA also enhanced TRAIL-induced apoptosis in Huh-7 cells. Finally, ectopic expression of mutant Akt (constitutive active) in HCC cells abolished TRAIL sensitization effect of bortezomib. Moreover, okadaic acid, a protein phosphatase 2A (PP2A) inhibitor, reversed down-regulation of P-Akt in bortezomib-treated cells, and PP2A knockdown by small interference RNA also reduced apoptosis induced by the combination of TRAIL and bortezomib, indicating that PP2A may be important in mediating the effect of bortezomib on TRAIL sensitization. Together, bortezomib overcame TRAIL resistance at clinically achievable concentrations in hepatocellular carcinoma cells, and this effect is mediated at least partly via inhibition of the PI3K/Akt pathway.

Induction of DNA Damage-Inducible Gene GADD45β Contributes to Sorafenib-Induced Apoptosis in Hepatocellular Carcinoma Cells

Markers that could accurately predict responses to the general kinase inhibitor sorafenib are needed to better leverage its clinical applications. In this study, we examined a hypothesized role in the drug response for the growth arrest DNA damage-inducible gene 45β (GADD45β), which is commonly underexpressed in hepatocellular carcinoma (HCC) where sorafenib may offer an important new therapeutic option. The anticancer activity of sorafenib-induced GADD45β expression was tested in a panel of HCC cell lines and xenograft models. We found that GADD45β mRNA and protein expression were induced relatively more prominently in HCC cells that were biologically sensitive to sorafenib treatment. GADD45β induction was not found after treatment with either the mitogen-activated protein kinase-extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor U0126 or the Raf inhibitor ZM336372, suggesting that GADD45β induction by sorafenib was independent of Raf/MEK/ERK signaling activity. However, c-Jun NH2-terminal kinase (JNK) kinase activation occurred preferentially in sorafenib-sensitive cells. Small interfering RNA-mediated knockdown of GADD45βor JNK kinase limited the proapoptotic effects of sorafenib in sorafenib-sensitive cells. We defined the -339/-267 region in the GADD45β promoter containing activator protein-1 and SP1-binding sites as a crucial region for GADD45β induction by sorafenib. Together, our findings suggest that GADD45β induction contributes to sorafenib-induced apoptosis in HCC cells, prompting further studies to validate its potential value in predicting sorafenib efficacy.

The Aurora kinase inhibitor VE-465 has anticancer effects in pre-clinical studies of human hepatocellular carcinoma

BACKGROUND/AIMS Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and novel therapies are urgently needed. Recently, aberrant expression of Aurora kinases has been reported in various human cancers including HCC. We sought to investigate the potential of a potent and selective Aurora kinase inhibitor, VE-465, for targeted therapy of HCC. METHODS Cytotoxicity effects of VE-465 were tested in Huh-7 and HepG2 cell lines. Inhibition of Aurora kinase activity was demonstrated by Western blotting and immunofluorescence staining. Mitotic perturbation was visualized by confocal microscopy. Cell cycle profiles and apoptosis were assessed by flow cytometry. In vivo efficacy was determined in nude mice with human HCC xenografts. RESULTS We demonstrated that VE-465 induced proliferation blockade, histone H3 (Ser10) dephosphorylation, mitotic disturbance, endoreduplication, and apoptosis in Huh-7 and HepG2 cells. We also found that VE-465 suppressed Aurora kinase activity, prevented tumor growth, and induced apoptosis in a Huh-7 xenograft model. CONCLUSIONS These findings show that VE-465 has potent anticancer effects in human HCC. Inhibitors of Aurora kinases may deserve further exploration as molecular targeted agents against HCC.

Combinations of Mtorc1 Inhibitor Rad001 with Gemcitabine and Paclitaxel for Treating Non-Hodgkin Lymphoma

Single-agent mammalian target of rapamycin complex 1 (mTORC1) inhibitors have recently been reported as effective salvage treatment in non-Hodgkin lymphoma (NHL). The combined effect of mTORC1 inhibitor, RAD001, with chemotherapeutic agents used for relapsed or refractory NHL was examined. Synergistic interactions were observed for RAD001 plus gemcitabine or paclitaxel in six NHL cell lines; enhanced gemcitabine- and paclitaxel-induced caspase-dependent apoptosis associated with down-regulation of mTOR signaling was detected. Synergistic interactions were also observed with RAD001 plus gemcitabine and paclitaxel. In conclusion, synergistic cytotoxicity was observed with RAD001 plus gemcitabine and paclitaxel in NHL cells. Combination therapy with these three drugs should be examined in patients with refractory or relapsed NHL.

IκB kinases increase Myc protein stability and enhance progression of breast cancer cells

BackgroundBoth IκB kinase (IKK) complex and oncgenic protein Myc play important roles in cancer progression, including cancer cell invasiveness and metastasis. The levels of Myc is regulated by the phosphorylation of Myc at Thr58 and Ser62.ResultsIn this study, we show that the expression of Myc is associated with IKKα and IKKβ in breast cancers and that Myc is an IKKs substrate. Suppression of IKK activity by either chemical inhibitor or transfection of kinase-dead mutants decreases the phosphorylation of Myc at Ser62 and enhances the degradation of Myc. Consequently, these treatments decrease the tumorigenic and invasive ability of breast cancer cells. Furthermore, doxorubicin, a frequently used anticancer drug in breast cancer, activates IKKs and Myc, thereby increasing invasiveness and tumorigenesis of breast carcinoma MCF7 cells. Inhibition of IKKs prevents these doxorubicin-induced effects.ConclusionsOur study indicates that IKKs tightly regulate Myc expression through prolonging protein stability, and suggests that IKKs are potentially therapeutic targets and that suppression of IKKs may be used following chemotherapy to reduce the risk of treatment-induced tumor progression.

Differential response to H. pylori eradication therapy of co-existing diffuse large B-cell lymphoma and MALT lymphoma of stomach—significance of tumour cell clonality and BCL10 expression†

We recently reported that low‐grade mucosa‐associated lymphoid tissue lymphoma (MALToma) and diffuse large B‐cell lymphoma (DLBCL) with MALToma (DLBCL[MALT]) of stomach are equally responsive to H. pylori eradication therapy (HPET) and that H. pylori‐independent status is closely associated with nuclear translocation of BCL10. However, co‐existing MALToma and DLBCL components of gastric DLBCL(MALT) may respond differentially to HPET and the underlying mechanism remains unclear. Tumour tissue samples from 18 patients with microdissectable co‐existing MALToma and DLBCL cells were studied. The clonality of lymphoma cells was examined by polymerase chain reaction‐based amplification of the CDR3 region of the IgH gene and confirmed by DNA sequence analysis. BCL10 expression was determined by immunohistochemistry. Differential response of co‐existing MALToma and DLBCL to HPET was defined as complete eradication of one component while the other component remained. Five (27.8%) of the 18 patients showed different IgH gene rearrangements in the two components and three (60%) of these five patients had differential response of MALToma and DLBCL to HPET. By contrast, 13 patients showed identical IgH gene rearrangements and only one (8%) of them had differential response of the two components to HPET (p = 0.044). Further, all four patients with differential response of MALToma and DLBCL to HPET showed nuclear expression of BCL10 in the H. pylori‐independent component and cytoplasmic expression of BCL10 in the H. pylori‐dependent component while the expression patterns of BCL10 were identical in both of these components in the 14 patients who had similar tumour response to HPET. We conclude that different clonality is a common reason for the differential response of co‐existing MALToma and DLBCL of gastric DLBCL(MALT) to HPET and that immunohistochemical examination of BCL10 expression may help to identify the co‐existence of these components. Copyright

Long-term follow-up of gastrectomized patients with mucosa-associated lymphoid tissue lymphoma: need for a revisit of surgical treatment.

Background:Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is characterized by multifocality of the tumors, which often scatter over the mucosa of the stomach and adjacent upper gastrointestinal tract, and is therefore theoretically not curable by surgical resection. Methods:We conducted a long-term follow-up study of 14 patients who received surgical treatment for gastric MALT lymphoma. Tissues from the surgical margins of the resected stomach were analyzed by polymerase chain reaction-based amplification of the complementarity-determining region 3 of the IgH gene for the presence of residual tumors. T (11;18)(q21;q21), a marker of Helicobacter pylori-independent MALT lymphoma, was analyzed by reverse transcription polymerase chain reaction. All living patients were restaged, and rebiopsied if suspicious lesions were identified. Results:At a median follow-up of 11.5 years, only 1 patient had evidence of tumor recurrence. Three patients with molecularly proven residual tumors in the surgical margin remained disease-free at 9.6 to 11.6 years. Five patients with t(11;18)(q21;q21) in the tumor cells were disease-free at 9.2 to 12.6 years. Conclusion:Our results indicate that surgical resection is a highly curative treatment for gastric MALT lymphoma, even for patients with residual tumor cells in the surgical margins, and for patients with H. pylori-independent tumors. A revisit of surgical treatment for gastric MALT lymphoma is mandatory.

Lack of compensatory pAKT activation and eIF4E phosphorylation of lymphoma cells towards mTOR inhibitor, RAD001

mTOR (mammalian target of rapamycin) inhibitors were recently found to be effective in the treatment of various human non-Hodgkins lymphomas (NHLs). We recently reported that RAD001, an mTOR inhibitor, suppressed the growth of lymphoma cells at concentrations much lower than those required for carcinomas. However, the basis for the enhanced sensitivity to RAD001 is unknown. Seven aggressive NHL cell lines and seven carcinoma cell lines were used in this study. Cell cycle was analysed by flow cytometry. pAKT (phosphorylated AKT) (Ser(473) and Thr(308)), p-p70S6K, p-4E-BP1, p-mTOR, p-eIF4E (phosphorylated eIF4E), cyclin A, cyclin E, cyclin D3, c-Myc and insulin receptor substrate-1 (IRS-1) protein expression were assessed by immunoblotting. The PI3K/AKT/mTOR (phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin) signalling pathway was constitutively expressed in all seven lymphoma cell lines. RAD001 down-regulated p-mTOR, p-p70S6K, p-4E-BP1, cyclin A, cyclin E, cyclin D3, and c-Myc, but did not affect IRS-1. In parallel with RAD001-induced inhibition of cell viability, a dose- and schedule- dependent down-regulation of pAKT and p-eIF4E expressions was demonstrated. In contrast, a compensatory activation of pAKT and p-eIF4E, was observed in seven carcinoma cells. These findings indicate that the basis for enhanced activity of mTOR inhibitors in NHL may be the lack of compensatory activation of AKT and eIF4E phosphorylation in lymphoma cells.

Abstract 364: Impact of glucocorticoid in patients with locally advanced esophageal cancer treated with concurrent chemoradiotherapy

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Background: Concerns about the effect of glucocorticoids (GC) on tumor growth and chemosensitivity have been raised recently. Our pervious study shows that GC receptor is highly expressed in esophageal squamous cell carcinoma (ESCC) tumor tissues (Histopathology 2008;52:314-324). This study sought to further characterize the GC effect on the efficacy of conventional anti-cancer therapy to ESCC. Materials and Methods:The in vitro study was performed in 2 esophagus cell lines: KYSE-70 and KYSE-410. The cell viability is determined by MTT assay and clonogenic assay. The effect of GC on cytotoxic treatment -induced apoptotic cell death was determined by flow cytometric and Western blot analysis. Further, we retrospectively analyzed impact of GC usage on the outcomes of 92 patients with locally advanced ESCC who received preoperative concurrent chemoradiotherapy in a prospective clinical trial. Among 92 locally advanced ESCC patients, 39 patients who received GC twice weekly for four to six weeks (a total of eight doses or more) and 53 patients who received GC only two doses in the first week at discretion of individual physicians. Results: In vitro study showed pretreatment of GC confer resistance to cytotoxic agents including paclitaxel, gemcitabine and 5-FU, and resistance to irradiation. The effect of increase chemo-resistance by GC may be through decrease of the apoptosis according to PI/annexin V staining flow cytometric study and Western blot study. In the retrospective clinical study, the two groups were well balanced with respect to disease stage and other prognostic factors. Multivariate analysis showed that corticosteroid usage and performance status were independently prognostic of survivals. The median overall survivals of the two-dose group the eight-dose-or-more group were 38.4 and 15.1 months, (p = 0.089), respectively. The median progression-free survivals were 27.5 and 9.4 months (p = 0.024), respectively. Conclusion: This data suggest that GC decrease chemo-sensitivity and radio-sensitivity of ESCC cells. Frequent usage of GC during concurrent chemoradiotherapy may have a detrimental effect on patients with locally advanced ESCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 364. doi:10.1158/1538-7445.AM2011-364