ABSTRACT
Multiple myeloma (MM) is an incurable hematological malignancy characterized by the clonal proliferation of malignant plasma cells. Despite the development of a diverse array of targeted drug therapies over the last decade, patients often relapse and develop refractory disease due to multidrug resistance. Obesity is a growing public health threat and a risk factor for multiple myeloma, although the mechanisms by which obesity contributes to MM growth and progression have not been fully elucidated. In the present study, we evaluated whether crosstalk between adipocytes and MM cells promoted drug resistance and whether this was amplified by obesity. Human adipose-derived stem cells (ASCs) from nineteen normal (BMI = 20-25 kg/m2), overweight (25-30 kg/m2), or obese (30-35 kg/m2) patients undergoing elective liposuction were utilized. Cells were differentiated into adipocytes, co-cultured with RPMI 8226 or U266B1 multiple myeloma cell lines, and treated with standard MM therapies, including bortezomib or a triple combination of bortezomib, dexamethasone, and lenalidomide. We found that adipocytes from overweight and obese individuals increased cell adhesion-mediated drug resistance (CAM-DR) survival signals in MM cells, and P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) drug transporter expression. Further, co-culture enhanced in vitro angiogenesis, MMP-2 activity, and protected MM cells from drug-induced decreases in viability. In summary, we provide an underlying mechanism by which obesity can impair the drug response to MM and allow for recurrence and/or disease progression.
ABSTRACT
LF82, an adherent invasive Escherichia coli pathobiont, is associated with ileal Crohn's disease, an inflammatory bowel disease of unknown etiology. Although LF82 contains no virulence genes, it carries several genetic differences, including single nucleotide polymorphisms (SNPs), that distinguish it from nonpathogenic E. coli. We have identified and investigated an extremely rare SNP that is within the highly conserved rpoD gene, encoding σ70, the primary sigma factor for RNA polymerase. We demonstrate that this single residue change (D445V) results in specific transcriptome and phenotypic changes that are consistent with multiple phenotypes observed in LF82, including increased antibiotic resistance and biofilm formation, modulation of motility, and increased capacity for methionine biosynthesis. Our work demonstrates that a single residue change within the bacterial primary sigma factor can lead to multiple alterations in gene expression and phenotypic changes, suggesting an underrecognized mechanism by which pathobionts and other strain variants with new phenotypes can emerge.
ABSTRACT
The BvgAS two-component system regulates virulence gene expression in Bordetella pertussis. Although precise three-dimensional structural information is not available for the response regulator BvgA, its sequence conservation with E. coli NarL and previous studies have indicated that it is composed of 3 domains: an N-terminal domain (NTD) containing the phosphorylation site, a linker, and a DNA-binding C-terminal domain (CTD). Previous work has determined how BvgACTD dimers interact with the promoter (P fhaB ) of fhaB, the gene encoding the virulence adhesin filamentous hemagglutinin. Here we use molecular modeling, FeBABE footprinting, and crosslinking to show that within the transcription complex of phosphorylated BvgA (BvgA â¼ P), B. pertussis RNAP, and P fhaB , the NTDs displace from the CTDs and are positioned at specific locations relative to the three BvgA â¼ P binding sites. Our work identifies a patch of the NTD that faces the DNA and suggests that BvgA â¼ P undergoes a conformational rearrangement that relocates the NTD to allow productive interaction of the CTD with the DNA.
