Zhentao Liu

Long-term green tea catechin administration prevents spatial learning and memory impairment in senescence-accelerated mouse prone-8 mice by decreasing Aβ1-42 oligomers and upregulating synaptic plasticity–related proteins in the hippocampus

The senescence-accelerated mouse prone-8 (SAMP8) is characterized by early onset of learning and memory deficits along with spontaneous overproduction of soluble beta-amyloid peptide (Abeta) in the brain. In our study, 4 month old male SAMP8 mice were orally administered 0.05% and 0.1% green tea catechins (GTC, w/v) in drinking water for 6 months. We found that a supplementation with 0.05% or 0.1% GTC prevented spatial learning and memory impairments of mice in the Morris water maze. Better performance of GTC-treated mice was associated with decreased levels of Abeta(1-42) oligomers in the hippocampus. The activity of the protein kinase A/cAMP-response element binding protein (PKA/CREB) pathway, one of the molecular targets of Abeta oligomers which is crucial for late long-term potentiation and long-term memory formation, was significantly increased after GTC administration. We also found that chronic 0.05% or 0.1% GTC consumption prevented the reductions of three representative proteins of synaptic function and synaptic structure, including brain-derived neurotrophic factor(BDNF), post-synaptic density protein-95 (PSD95) and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). These results demonstrated that long-term 0.05% or 0.1% green tea catechin administration may prevent spatial learning and memory decline of SAMP8 mice by decreasing Abeta(1-42) oligomers and upregulating synaptic plasticity-related proteins in the hippocampus.

Long-term administration of green tea catechins prevents age-related spatial learning and memory decline in C57BL/6 J mice by regulating hippocampal cyclic amp-response element binding protein signaling cascade.

Flavonoid-rich foods have been shown to be effective at reversing age-related deficits in learning and memory in both animals and humans. However, little investigation of the preventative effects of flavonoids on the naturally aged animals was reported. In our study, 14-month-old female C57BL/6 J mice were orally administered 0.025%, 0.05% and 0.1% green tea catechins (GTC, w/v) in drinking water for 6 months; we found that a supplementation with 0.05% or 0.1% GTC prevented age-related spatial learning and memory decline of mice in the Morris water maze. Better performance of GTC-treated mice was associated with increased levels of cAMP-response element binding protein (CREB) phosphorylation in the hippocampus. The expressions of brain-derived neurotrophic factor (BDNF) and Bcl-2, two target genes of CREB which can exhibit long-term regulatory roles in synaptic plasticity and synaptic structure, were also increased. We also found that long-term 0.05% or 0.1% GTC administration prevented age-related reductions of two representative post-synaptic density proteins PSD95 and Ca(2+)/calmodulin-dependent protein kinase II, suggesting that synaptic structural changes may be involved. These results demonstrated that long-term 0.05% or 0.1% green tea catechin administration may prevent age-related spatial learning and memory decline of female C57BL/6 J mice by regulating hippocampal CREB signaling cascade.

HER2 copy number of circulating tumour DNA functions as a biomarker to predict and monitor trastuzumab efficacy in advanced gastric cancer

BACKGROUNDnHER2 status is significant to trastuzumab therapy; however, it is difficult to determine HER2 status accurately with few pieces of biopsies from advanced gastric cancer (AGC) due to highly heterogeneity and invasive behaviour, which will be investigated in this study.nnnMETHODSnFifty-six patients with AGC were included in this study. Primary tumour tissues and matched plasmas before medication from 36 patients were retrospectively collected, and the other 20 patients with primary tumour tissues and paired plasmas were prospectively collected. HER2 expression and amplification in 56 tumour tissues were determined by immunohistochemistry (IHC) and dual in situ hybridisation (DISH), and HER2 copy number in 135 circulating tumour DNAs (ctDNAs) was judged by next-generation sequencing.nnnRESULTSnFor tumour tissues, HER2 amplification by DISH was most commonly found in patients with HER2 score 3+by IHC. For plasmas, HER2 amplification defined as HER2 copy number >2.22 was identified in 26 of 56 patients. There was a high concordance of HER2 amplification between ctDNA and tumour tissues, suggesting that ctDNA could function as an alternative to screen HER2-targeted population. Moreover, the changes of HER2 copy number in ctDNA could efficiently monitor trastuzumab efficacy, the power of which was superior to commonly used markers carcinoembryonic antigen (CEA) and CA199, suggesting its potential role in clinical practice.nnnCONCLUSIONnctDNA for HER2 analysis was strongly recommended to serve as a surrogate to screen trastuzumab-suitable population and monitor trastuzumab efficacy.

CDK4/6 inhibitor-SHR6390 exerts potent antitumor activity in esophageal squamous cell carcinoma by inhibiting phosphorylated Rb and inducing G1 cell cycle arrest

BackgroundCell cycle dysregulation is common in human malignancies, and CDK4/6 inhibitors targeting cell cycle have potential antitumor activity. SHR6390 is a novel small molecule inhibitor specifically targeting the CDK4/6 pathway. However, the role of SHR6390 in esophageal squamous cell carcinoma (ESCC) remains unknown, which will be investigated in our study.MethodsEca 109, Eca 9706, and KYSE-510 ESCC cell lines were chosen for further analysis. The effect of SHR6390 on cell viability, cell cycle and cell apoptosis, the status of kinases in Cyclin D1-CDK4/6-Rb pathway were determined by MTS assay, flow cytometry, and western blotting, respectively. Cell-derived and patient-derived xenografts were established to investigate the effects of drugs in vivo.ResultsSHR6390 could suppress cell proliferation in vitro cell lines and inhibit tumor growth in vivo PDX models with different drug susceptibility. The effective treatment of SHR6390 induced the inhibition of phosphorylated Rb and cell cycle arrest at G1 phase both in cell lines and in xenografts. SHR6390 combined with paclitaxel or cisplatin offered synergistic inhibitory effects in cell-derived xenografts especially in Eca 9706 xenografts which showed relative lower sensitivity of SHR6390 single. Moreover, low expression of CDK6 and/or high expression of Cyclin D1 might be associated with high sensitivity of SHR6390, which would be validated in the future.ConclusionsCDK4/6 inhibitor-SHR6390 exerted potential antitumor activity against ESCC cell lines and xenografts, and evaluation of CDK6 and Cyclin D1 expressions might be helpful to select patients beneficial from SHR6390, which provided evidences for future clinical trials.

Dual PI3K/mTOR inhibitor BEZ235 as a promising therapeutic strategy against paclitaxel-resistant gastric cancer via targeting PI3K/Akt/mTOR pathway

Paclitaxel (PTX) is widely used in the front-line chemotherapy for gastric cancer (GC), but resistance limits its use. Due to the lack of proper models, mechanisms underlying PTX resistance in GC were not well studied. Using established PTX-resistant GC cell sublines HGC-27R, we for the first time integrated biological traits and molecular mechanisms of PTX resistance in GC. Data revealed that PTX-resistant GC cells were characterized by microtubular disorders, an EMT phenotype, reduced responses to antimitotic drugs, and resistance to apoptosis (marked by upregulated β-tubulin III, vimentin, attenuated changes in G2/M molecules or pro-apoptotic factors in response to antimitotic drugs or apoptotic inducers, respectively). Activation of the phosphoinositide 3-kinase, the serine/threonine kinase Akt and mammalian target of rapamycin (PI3K/Akt/mTOR) and mitogen-activated protein kinase (MAPK) pathways were also observed, which might be the reason for above phenotypic alternations. In vitro data suggested that targeting these pathways were sufficient to elicit antitumor responses in PTX-resistant GC, in which the dual PI3K/mTOR inhibitor BEZ235 displayed higher therapeutic efficiency than the mTOR inhibitor everolimus or the MEK inhibitor AZD6244. Antitumor effects of BEZ235 were also confirmed in mice bearing HGC-27R tumors. Thus, these data suggest that PI3K/Akt/mTOR and MAPK pathway inhibition, especially PI3K/mTOR dual blockade, might be a promising therapeutic strategy against PTX-resistant GC.

Establishment and genomic characterizations of patient-derived esophageal squamous cell carcinoma xenograft models using biopsies for treatment optimization

BackgroundSquamous cell carcinoma is the dominant type of esophageal cancer in China with many patients initially diagnosed at advanced stage. Patient-derived xenografts (PDX) models have been developed to be an important platform for preclinical research. This study aims to establish and characterize PDX models using biopsy tissue from advanced esophageal cancer patients to lay the foundation of preclinical application.MethodsFresh endoscopic biopsy tissues were harvested from patients with advanced esophageal cancer and implanted subcutaneously into NOD/SCID mice. Then, the PDXs were serially passaged for up to four generations. Transplantation was analyzed and genomic characteristics of xenografts were profiled using next-generation sequencing.ResultsTwenty-five PDX models were established (13.3%, 25/188). The latency period was 75.12xa0±xa019.87xa0days (50–120xa0days) for the first passage and it decreased with increasing passaging. Other than tumor stages, no differences were found between transplantations of xenografts and patient characteristics, irrespective of chemotherapy. Histopathological features and chemosensitivity of PDXs were in great accordance with primary patient tumors. Each PDX was assessed for molecular characteristics including copy number variations, somatic mutations, and signaling pathway abnormalities and these were similar to patient results.ConclusionsOur PDX models were established from real time biopsies and molecularly profiled. They might be promising for drug development and individualized therapy.

Characterization and validation of potential therapeutic targets based on the molecular signature of patient-derived xenografts in gastric cancer

BackgroundPatient-derived xenograft (PDX) models with definite molecular signature are attractive preclinical models for development of novel targeted drugs. Here, we profiled and explored potential therapeutic targets based on characterized PDX models for advanced gastric cancer (AGC).MethodsThe genomic variation and molecular profile of 50 PDX models from AGC patients were analyzed by targeted next-generation sequencing, in situ hybridization, and immunohistochemistry. The antitumor activities of several targeted drugs were investigated in the PDX models. Furthermore, response biomarkers were explored.ResultsEach PDX model had individual histopathological and molecular features, and recurrent alterations in the MAPK, ErbB, VEGF, mTOR, and cell cycle signaling pathways were major events in these PDX models. Several potential drug targets, such as EGFR, MET, and CCNE1, were selected and validated in this study. Volitinib demonstrated strong antitumor activity in PDX models with MET and phosphorylated MET (pMET) overexpression. The EGFR monoclonal antibodies BK011 and cetuximab inhibited tumor growth in a PDX model with EGFR amplification. Afatinib inhibited tumor growth in the PDX models with EGFR amplification, EGFR overexpression, or HER2 amplification. Apatinib was more sensitive in the PDX models with high microvessel density. The CDK1/2/9 inhibitor AZD5438 had superior anti-tumor activity in two models with higher copy number of CCNE1.ConclusionsPDX models with defined molecular signature are useful for preclinical studies with targeted drugs, and the results should be validated in larger studies with PDX models or in clinical trials.

Targeting c-Myc: JQ1 as a promising option for c-Myc-amplified esophageal squamous cell carcinoma

c-Myc amplification-induced cell cycle dysregulation is a common cause for esophageal squamous cell carcinoma (ESCC), but no approved targeted drug is available so far. The bromodomain inhibitor JQ1, which targets c-Myc, exerts anti-tumor activity in multiple cancers. However, the role of JQ1 in ESCC remains unknown. In this study, we reported that JQ1 had potent anti-proliferative effects on ESCC cells in both time- and dose-dependent manners by inducing cell cycle arrest at G1 phase, cell apoptosis, and the mesenchymal-epithelial transition. Follow-up studies revealed that both c-Myc/cyclin/Rb and PI3K/AKT signaling pathways were inactivated by JQ1, as indicated by the downregulation of c-Myc, cyclin A/E, and phosphorylated Rb, AKT and S6. Tumor suppression induced by JQ1 in c-Myc amplified or highly expressed xenografts was higher than that in xenografts with low expression, suggesting its potential role in prediction. In conclusion, targeting c-Myc by JQ1 could cause significant tumor suppression in ESCC both inxa0vitro and inxa0vivo. Also, c-Myc amplification or high expression might serve as a potential biomarker and provide a promising therapeutic option for ESCC.

Gimatecan exerts potent antitumor activity against gastric cancer in vitro and in vivo via AKT and MAPK signaling pathways

BackgroundWe investigated antitumor activity and underlying mechanisms of DNA topoisomerase I (TopI) inhibitor gimatecan and irinotecan in gastric cancer (GC) in vitro cell lines and in vivo patient-derived xenograft (PDX) models.MethodsGC cell lines SNU-1, HGC27, MGC803 and NCI-N87 were used to evaluate cell viability and apoptosis after gimatecan or irinotecan treatment, using a cell proliferation assay and flow cytometry, respectively. DNA TopI expression and critical molecules of PI3K/AKT, MAPK and apoptosis signaling pathways were analyzed with western blot. For in vivo studies, five PDXs models were treated with gimatecan or irinotecan to assess its antitumor activity. Immunohistochemistry staining of Ki-67 was performed after mice were sacrificed.ResultsGimatecan inhibited the proliferation of GC cells in vitro in a dose- and time-dependent manner by inducing apoptosis, and gimatecan had greater inhibitory effects than irinotecan. In addition, both gimatecan and irinotecan demonstrated significant tumor growth inhibition in in vivo PDX models. Gimatecan treatment significantly inhibited the expression of DNA TopI, phosphorylated AKT (pAKT), phosphorylated MEK (pMEK) and phosphorylated ERK (pERK). Meanwhile, gimatecan could also activate the JNK2 and p38 MAPK pathway as indicated by upregulation of phosphorylated p38 MAPK (p-p38) and phosphorylated JNK2 (pJNK2).ConclusionsFor the first time, we have shown that the antitumor activity of gimatecan in GC via suppressing AKT and ERK pathway and activating JNK2 and p38 MAPK pathway, which indicated that gimatecan might be an alternative to irinotecan in the treatment of GC.

Characterization of Aurora A and Its Impact on the Effect of Cisplatin-Based Chemotherapy in Patients with Non–Small Cell Lung Cancer

BACKGROUND AND OBJECTIVE: Aurora A, as a member of serine/threonine kinase family and a common characteristic of epithelial cancers, plays a critical role in cell mitosis. However, the clinical significance of Aurora A in non–small cell lung cancer (NSCLC) remains undetermined. METHODS: The expression of Aurora A in NSCLC and paired normal adjacent lung tissues was determined by immunohistochemistry, Western blot, and reverse transcriptase polymerase chain reaction. Receiver operating characteristic (ROC) curve analysis was employed to determine a cutoff score for Aurora A expression in a training set (n = 135). For validation, the ROC-derived cutoff score was subjected to analysis of the association of Aurora A expression with patient outcome and clinicopathological characteristics in a testing set (n = 128) and overall patients (n = 263). The correlation of Aurora A with cisplatin resistance and epithelial-mesenchymal transition (EMT) was examined in vitro in NSCLC cells by overexpression or knockdown of Aurora A. RESULTS: Aurora A expression was significantly upregulated in tumor tissues compared with paired normal tissues (P < .01). The expression of Aurora A was closely associated with clinical stage, lymph node metastasis, and recurrence and was an independent prognostic parameter in multivariate analysis. High level of Aurora A expression predicted poorer overall survival and disease-free survival in NSCLC patients treated with cisplatin-based adjuvant chemotherapy. In vitro data showed that overexpression or knockdown of Aurora A resulted in increased or decreased cellular resistance to cisplatin. Furthermore, inhibition of Aurora A reversed the EMT process. CONCLUSIONS: Aurora A was identified as an inferior prognostic and cisplatin-resistant biomarker in NSCLC patients, which provided potential evidences for therapeutic target and reversing drug resistance.