KCNB1 gene polymorphisms and related indel as predictor biomarkers of treatment response for colorectal cancer - toward a personalized medicine.

The KCNB1 gene variants were differentially associated with cancers. However, their association with colorectal cancer has not yet been explored. We investigated the contribution of the KCNB1 gene variants rs3331, rs1051295, and indel (insertion/deletion) rs11468831 Polymorphism as predictors of the treatment response in colorectal cancer patients. A retrospective study, which involved 291 Tunisian colorectal cancer patients (aged 60.0 ± 13.1 years), who were stratified into responder and non-responder groups, according to TNM stages and their responsiveness to chemotherapy based on fluorouracil. KCNB1 genotyping was performed with amplification-refractory mutation system-polymerase chain reaction, and was confirmed by Sanger sequencing. Sex-specific response was found and colorectal cancer females are less likely to achieve a positive response during the chemotherapy strategy, compared to males. Weight and body mass index, tumor size, and tumor localization are considered as predictive factors to treatment responsiveness. Carriage of rs11468831 Ins allele was significantly associated with successful therapy achievement (p adjusted < 0.001). Stratification of colorectal cancer patients' response according to tumor localization and TNM stages reveals negative association of rs3331 Major allele to treatment response among the patients with advanced cancer stages (subgroup G2). The presence of rs3331 (homozygous minor) C/C genotype was positively associated with decline in carcino-embryonic antigen (p = 0.043) and CA19-9 (p = 0.014) serum levels. On the other hand, the presence of rs1051295 (homozygous minor) A/A genotype was correlated with marked decline in CA19-9 serum levels. KCNB1 haplotype did not reveal any association between haplotypes and treatment response. The results obtained suggest that gender-specific strategies for screening treatment and prevention protocols as well as KCNB1 variants may constitute an effective model for ongoing personalization medicine.

Apparent degradation forms of rhG-CSF under forced conditions: Insights for better quality-control of bioproducts.

Stability and quality control of therapeutic protein formulations is a substantial part of drug development process. The objective of this study is to obtain information about stability of a recombinant human granulocyte colony stimulating factor (rhG-CSF) against various stress factors. This will play a crucial role in the finished product formulation development. In this study, rhG-CSF was exposed to various chemical and physical stress conditions at different levels in order to identify degradation pathways and the nature of impurities generated. Experiments were performed by a combination of orthogonal analytical techniques (reversed phase chromatography (RP-HPLC), size exclusion chromatography (SEC-HPLC), polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF)) to set and characterize the different degraded samples. The SEC-HPLC results suggest that the major degradation factors generating aggregated forms of the protein are basically thermal stress, freeze-thaw cycles and vortexing. Meanwhile, deamidated rhG-CSF was induced by basic pH as shown by IEF electrophoregram. As well, oxidized forms were generated increasingly with the time of exposure to hydrogen peroxide as outlined by RP-HPLC analysis. Based on these results, it was possible to define the storage and handling conditions of rhG-CSF finished product during its shelf life.

Optimization of PEGylation reaction time and molar ratio of rhG-CSF toward increasing bioactive potency of monoPEGylated protein.

PEGylation is one of the strategies used for enhancing in vivo residence time of recombinant human Granulocyte Colony-Stimulating Factor (rhG-CSF) and therefore reducing in dose frequency to better fit with patient comfort treatment. In this study, three methoxy polyethylene glycol propionaldehydes (mPEG- ALD) of 10, 20 and 30kDa MW were utilized to produce biologically active monoPEGylated rhG-CSF with enhanced molecular weight. PEGylation reactions were carried out at room temperature and pH 5.0 in the presence of cyanoborohydride and two mPEG-ALD: protein molar ratios (3:1 and 5:1). The reactions were monitored with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography (SEC-HPLC). The results showed that a 2h reaction with 5:1 mPEG-ALD: protein molar ratio was sufficient to direct the reaction toward optimal yields of monoPEGylated protein (86%). Subsequently, isolation of the monoPEGylated forms was successfully achieved. The purified products were compared with respect to their purity (≥95%), identity and isoelectric focusing parameter characteristics. Biological potencies were measured by cell proliferation assay and showed 20.80-42.73% retention of bioactivities. This study highlights the possible improvement of rhG-CSF efficiency by PEGylation. Further studies will investigate in vitro and in vivo immunogenicity and toxicity of monoPEGylated conjugates.

Dromedary immune response and specific Kv2.1 antibody generation using a specific immunization approach.

Voltage-gated potassium (Kv) channels form cells repolarizing power and are commonly expressed in excitable cells. In non-excitable cells, Kv channels such as Kv2.1 are involved in cell differentiation and growth. Due to the involvement of Kv2.1 in several physiological processes, these channels are promising therapeutic targets. To develop Kv2.1 specific antibody-based channel modulators, we applied a novel approach and immunized a dromedary with heterologous Ltk- cells that overexpress the mouse Kv2.1 channel instead of immunizing with channel protein fragments. The advantage of this approach is that the channel is presented in its native tetrameric configuration. Using a Cell-ELISA, we demonstrated the ability of the immune serum to detect Kv2.1 channels on the surface of cells that express the channel. Then, using a Patch Clamp electrophysiology assay we explored the capability of the dromedary serum in modulating Kv2.1 currents. Cells that were incubated for 3h with serum taken at Day 51 from the start of the immunization displayed a statistically significant 2-fold reduction in current density compared to control conditions as well as cells incubated with serum from Day 0. Here we show that an immunization approach with cells overexpressing the Kv2.1 channel yields immune serum with Kv2.1 specific antibodies.