Heterogeneity of aberrant immunoglobulin expression in cancer cells

Accumulating evidence has shown that immunoglobulin(Ig)is‘unexpectedly’expressed by epithelial cancer cells and that it can promote tumor growth.The main purpose of this study was to explore the components of the cancerous Ig and its possible function.The presence of cancerous Ig in the Golgi apparatus was confirmed by immunofluorescence,indirectly suggesting that the cancerous Ig was processed and packaged in cancer cells.Western blot analysis and ELISA results indicated that cancer cells produced membrane Ig and secreted Ig into the supernatant fraction.The cancerous Ig consists of an a heavy chain and a k light chain.Finally,by analyzing the Ig components pulled down by protein A beads,the cancerous Ig was found to be structurally distinct from normal Ig.The cancerous Ig was truncated or aberrant.Although the underlying mechanism that causes the abnormalities has not been determined,our current discoveries strengthen our previous findings and promise fruitful future explorations.

AID expression increased by TNF-α is associated with class switch recombination of Igα gene in cancers

Recently, immunoglobulins （Igs） were unexpectedly found to be expressed in epithelial cancers. Immunoglobulin class switching or class switch recombination （CSR） is a natural biological process that alters a B cell＇s production of antibodies （immunoglobulins） from one class to another. However, the mechanism of CSR of Iggenes in cancer is still unknown. Here, we confirmed by detecting the hallmark of CSR that the Iga gene in cancer underwent CSR. Then we focused on activation-induced cytidine deaminase （AID）, a crucial factor for initiating CSR. Further studies using tumor necrosis factor （TNF）-α stimulation and specific inhibitor of NF-KB revealed that TNF-α could increase AID expression through NF-κB signaling. Finally, we demonstrated that AID could co-localize with protein kinase A and bind to the switching （Sα） region of the Igα gene. Overexpression of AID obviously enhanced Igα heavy chain expression and its binding ability to the Sa region. These findings indicated that TNF-α-induced AID expression is involved with CSR in cancer.

A novel variant in TBX20 （p.DI76N） identified by whole-exome sequencing in combination with a congenital heart disease related gene filter is associated with familial atrial septal defect

Congenital heart disease （CHD） is the leading cause of birth defects, and its etiology is not completely understood. Atrial septal defect （ASD） is one of the most common defects of CHD. Previous studies have demonstrated that mutations in the transcription factor T-box 20 （TBX20） contribute to congenital ASD. Whole-exome sequencing in combination with a CHD-related gene filter was used to detect a family of three generations with ASD. A novel TBX20 mutation, c.526G〉A （p.D176N）, was identified and co-segregated in all affected members in this family. This mutation was predicted to be deleterious by bioinformatics programs （SIFT, Polyphen2, and MutationTaster）. This mutation was also not presented in the current Single Nucleotide Polymorphism Database （dbSNP） or National Heart, Lung, and Blood Institute （NHLBI） Exome Sequencing Project （ESP）. In conclusion, our finding expands the spectrum of TBX20 mutations and provides additional support that TBX20 plays important roles in cardiac development. Our study also provided a new and cost-effective analysis strategy for the genetic study in small CHD pedigree.