Evaluation of different IRES-mediated tricistronic plasmid designs for expression of an anti-PCSK9 biosimilar monoclonal antibody in CHO cells.

OBJECTIVES: To compare different approaches for the expression of an anti-PCSK9 biosimilar monoclonal antibody (mAb) in CHO cells using IRES-mediated tricistronic plasmid vectors combining different signal peptides, IRES elements and selection markers. RESULTS: Transient transfection indicated a similar level of secreted mAb 48 h post-transfection for all constructs. However, transfections carried out with circular plasmids showed a higher expression than with linearized plasmids. After two months under selection pressure, only part of the transfected pools recovered. The cultures co-transfected using two antibiotics as selection markers for double selection did not recover. Growth, metabolism and mAb production profiles of the only part of the transfected pools recovered resulting stable pools were compared and the stable pool transfected with circular L1-LC-IRES-H7-HC-IRES-NEO plasmid was chosen for further studies, due to higher cell growth and mAb production. Critical quality attributes of the protein A-purified mAb such as purity, homogeneity, binding affinity to PCSK9, and amino acid sequence were assessed confirming the success of the approach adopted in this study. CONCLUSIONS: The expression platform proposed showed to be efficient to produce a high-quality anti-PCSK9 mAb in stable CHO cell pools and provides benchmarks for fast production of different mAbs for characterization, formulation studies and pre-clinical investigation.

cDNA microarray analysis of human keratinocytes cells of patients submitted to chemoradiotherapy and oral photobiomodulation therapy: pilot study.

Oral mucositis is an acute toxicity that occurs in patients submitted to chemoradiotherapy to treat head and neck squamous cell carcinoma. In this study, we evaluated differences in gene expression in the keratinocytes of the oral mucosa of patients treated with photobiomodulation therapy and tried to associate the molecular mechanisms with clinical findings. From June 2009 to December 2010, 27 patients were included in a randomized double-blind pilot study. Buccal smears from 13 patients were obtained at days 1 and 10 of chemoradiotherapy, and overall gene expression of samples from both dates were analyzed by complementary DNA (cDNA) microarray. In addition, samples from other 14 patients were also collected at D1 and D10 of chemoradiotherapy for subsequent validation of cDNA microarray findings by qPCR. The expression array analysis identified 105 upregulated and 60 downregulated genes in our post-treatment samples when compared with controls. Among the upregulated genes with the highest fold change, it was interesting to observe the presence of genes related to keratinocyte differentiation. Among downregulated genes were observed genes related to cytotoxicity and immune response. The results indicate that genes known to be induced during differentiation of human epidermal keratinocytes were upregulated while genes associated with cytotoxicity and immune response were downregulated in the laser group. These results support previous clinical findings indicating that the lower incidence of oral mucositis associated with photobiomodulation therapy might be correlated to the activation of genes involved in keratinocyte differentiation.

XAF1 mRNA expression improves progression-free and overall survival for patients with advanced bladder cancer treated with neoadjuvant chemotherapy.

PURPOSE: The aim of this study was to investigate whether mRNA expression of the apoptosis-associated genes, XAF1 and XIAP, in bladder cancer patients correlates with response to neoadjuvant treatment. METHODS: Gene expression was analyzed by a real-time quantitative PCR method in paired samples from 14 bladder cancer patients treated with a combination of neoadjuvant gemcitabine and cisplatin. The prognostic significance of XAF1 and XIAP mRNA expression as well as the correlation with several clinical and pathological findings were evaluated. RESULTS: The clinical response in the XAF1-high subset (n = 5) was remarkably higher compared with the XAF1-low subset (n = 9) (100% vs. 44.4%; P = 0.038). These results translated into a notably improvement of progression-free survival (PFS) in the XAF1-high subset (log-rank P = 0.012). In addition, patients in the XAF1-high subset had a 3.9-fold decreased chance of dying from the disease (hazard ratio for death (HR), 0.257; (CI 95%), 0.043-1.536, P = 0.036). When we evaluated the expression of XIAP, although an inverse correlation was found between expression and pathological response, there were no statistically significant associations with the clinical response, the length of PFS, and OS. CONCLUSIONS: This is one of the few studies to address the role of XAF1 in a clinical setting. The data presented here identify XAF1 as a novel predictive and prognostic factor in bladder cancer patients. Furthermore, our observations are in line with previous studies, which point towards XAF1 as a tumor-suppressor gene. Nonetheless, additional studies, both mechanistic and translational, are warranted and may help not only in corroborating the role of XAF1 as a prognostic marker, but also as a potential target for anticancer therapy.