Purpose: PI3K-Akt is overexpressed in 50% to 70% of pancreatic ductal adenocarcinoma (PDAC). The hypothesis of this study is that PI3K and EGFR coinhibition may be effective in PDAC with upregulated PI3K-Akt signaling.Experimental Design: Multiple inhibitors were tested on five PDAC cell lines. EGFR inhibitor (EGFRi)-resistant cell lines were found to have significantly overexpressed AKT2 gene, total Akt, and pAkt. In vitro erlotinib-resistant (ER) cell models (BxPC-ER and PANC-ER) with highly constitutively active PI3K-Akt were developed. These and their respective parent cell lines were tested for sensitivity to erlotinib, IGFIR inhibitor NVP-AEW541 (AEW), and PI3K-alpha inhibitor NVP-BYL719 (BYL), alone or in combination, by RTK-phosphoarray, Western blotting, immunofluorescence, qRT-PCR, cell proliferation, cell cycle, clonogenic, apoptosis, and migration assays. Erlotinib plus BYL was tested in vivo.Results: Erlotinib acted synergistically with BYL in BxPC-ER (synergy index, SI ¼ 1.71) and PANC-ER (SI ¼ 1.44). Treatment of ER cell lines showing upregulated PI3K-Akt with erlotinib plus BYL caused significant G 1 cell-cycle arrest (71%, P < 0.001; 58%, P ¼ 0.003), inhibition of colony formation (69% and 72%, both P < 0.001), and necrosis and apoptosis (75% and 53%, both P < 0.001), more so compared with parent cell lines. In primary patient-derived tumor subrenal capsule (n ¼ 90) and subcutaneous (n ¼ 22) xenografts, erlotinib plus BYL significantly reduced tumor volume (P ¼ 0.005). Strong pEGFR and pAkt immunostaining (2þ/3þ) was correlated with high and low responses, respectively, to both erlotinib and erlotinib plus BYL.Conclusion: PDAC with increased expression of the PI3K-Akt pathway was susceptible to PI3K-EGFR coinhibition, suggesting oncogenic dependence. Erlotinib plus BYL should be considered for a clinical study in PDAC; further evaluation of pEGFR and pAkt expression as potential positive and negative predictive biomarkers is warranted. Clin Cancer Res; 20(15); 4047-58. Ó2014 AACR.
Induction of antitumor immunity using autologous tumor proteins is an attractive approach to cancer therapy. However, better methods and stimulants to present these autologous proteins back to the immune system are needed. Here, we identify streptavidin as a novel carrier protein and stimulant, and test the efficacy of both syngeneic (rat) and autologous vaccines (dogs) using streptavidin in combination with reduced soluble tumor proteins. Initial syngeneic vaccine studies in the 9L rat glioma model were used to optimize vaccine dose and selectivity. Cytokine and blood analysis was used to monitor the response. Rats receiving two vaccinations of syngeneic tumor vaccine demonstrated a statistically significant (P < 0.05) survival advantage compared with controls (adjuvant only). Notably, vaccination also led to remission rates of between 30% and 60% in the aggressive 9L glioma model. Antibodies to streptavidin were detected in the serum of vaccinated rats; however, antibody levels did not correlate with the response. The cytokine TNF-a was upregulated in vaccine-treated rats, whereas ICAM1 was downregulated. After engraftment, vaccinated rats maintained CD4þ T cells, and total lymphocyte levels closer to normal baseline than those in the controls. Twenty-five dogs treated with autologous vaccine preparations using streptavidin as a stimulant showed no adverse reactions, irrespective of additional chemotherapy and other medications. In this study, we developed a novel method for producing syngeneic and autologous vaccines using streptavidin selectivity and immunogenicity. These vaccines show efficacy in the 9L glioma rat model. Safety was also demonstrated in canine patients presenting with cancer treated with autologous vaccine.
DNA Methylation, 5meC, is an epigenetic modification that acts as an important regulator of genomic stability and gene expressivity. Genome-wide changes in methylation have been associated with lineage-specific changes in gene expression profiles during development and in some cell-based pathologies, including oncogenesis. Cost-effective and rapid platforms for the detection of changes in the global levels of methylation are of value for the investigation of the processes that regulate methylation. Flow cytometry allows rapid and quantitative analysis of epitopes within a large number of cells. We have recently optimised the conditions required for valid detection of 5meC by immunofluorescence microscopy. These studies showed that immunological detection of 5meC requires the sequential denaturation of chromatin by a brief period of acidification followed by a partial tryptic digestion step. We have assessed the reliability of flow cytometry for the detection of changes in 5meC when coupled with this optimised epitope retrieval strategy. This study provides support for the use of high throughput screening of 5meC by flow cytometry for the analysis of the epigenetic regulation of important cell transitions.
Background and Aim: Processing and cryopreservation is known to reduce the viability and absolute number of CD34+ haematopoetic stem cells (HSCs). DNA damage and subsequent apoptosis of stem cells may occur as a result of prior treatment regimens or from the accumulation of reactive oxygen species (ROS) during the freeze/thawing process. In our recent study we demonstrated that two distinct populations of HSCs are present in all cryopreserved patient samples, based on their ROS expression; these we defined as ROShigh and ROSlow. The significant correlation between the percentage of ROShigh HSCs in the graft and neutrophil recovery following transplant shown in our study suggests that some degree of ROS accumulation may play an important role in promoting neutrophil engraftment following autologous HSC transplantation (AHSCT) (Bai et al 2018). The current study examined the association between ROS levels and DNA damage in cryopreserved HSCs and whether these correlated with time to neutrophil and platelet engraftment following AHSCT. Methods: Cryopreserved HSC samples from 51 patients who underwent AHSCT were studied. HSC's were defined as CD45+/CD34+. DNA damage and intracellular ROS levels were assessed using an antibody against the phosphorylated form of histone H2Ax (γH2Ax) and 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA), respectively. Data acquisition and analysis were performed by flow cytometry. Results: We observed a proportion of HSC in each sample that expressed elevated levels of gH2Ax. The median percentage of γH2Ax expressing CD34+ cells was 54.6% (range 3.4 - 98.4%). We observed a strong correlation between ROShigh and γH2Ax levels in terms of the dose of cells/kg infused (p < 0.001, r = 0.72). The ratio of ROShigh/γH2Ax-expressing HSCs was inversely associated with delayed neutrophil engraftment (p = 0.03, r = -0.31). The cohort was divided into group 1 and group 2 based on ROShigh/γH2Ax ratios of >1 (n = 32) and ≤1 (n = 18) respectively. Median days to neutrophil engraftment were 12 (range 9-18), in group 1 and 15 (range 9-28) in group 2, (p = 0.007). Median days to platelet engraftment were 17 (range 10-28) in group 1 and 21.5 (range 14-55) in group 2, (p = 0.001). Median days to platelet count of >50 (plt50) was 18.5 (range 12-28) in group 1 and 22 (range 16-75) in group 2, (p = 0.001). In group 2, significant correlations were noted between the ROShigh/γH2Ax ratio and time to neutrophil engraftment (r = -0.54, p=0.025), plt20 (r = -0.64, p=0.004) and plt50 (r = -0.7, p = 0.002). Conclusion: Our data suggest that DNA damage in CD34+ and accumulation of ROS may impact upon the time to engraftment of HSCs. Calculating a ratio of ROShigh/γH2Ax expression may be useful in predicting engraftment time following autologous transplantation. Disclosures No relevant conflicts of interest to declare.
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