Potential role of septins in oral carcinogenesis: An update and avenues for future research

SEPTIN2 and STATHMIN Regulate CD99-Mediated Cellular Differentiation in Hodgkin's Lymphoma

Hodgkin’s lymphoma (HL) is a lymphoid neoplasm characterized by Hodgkin’s and Reed-Sternberg (H/RS) cells, which is regulated by CD99. We previously reported that CD99 downregulation led to the transformation of murine B lymphoma cells (A20) into cells with an H/RS phenotype, while CD99 upregulation induced differentiation of classical Hodgkin’s lymphoma (cHL) cells (L428) into terminal B-cells. However, the molecular mechanism remains unclear. In this study, using fluorescence two-dimensional differential in-gel electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS), we have analyzed the alteration of protein expression following CD99 upregulation in L428 cells as well as downregulation of mouse CD99 antigen-like 2 (mCD99L2) in A20 cells. Bioinformatics analysis showed that SEPTIN2 and STATHMIN, which are cytoskeleton proteins, were significantly differentially expressed, and chosen for further validation and functional analysis. Differential expression of SEPTIN2 was found in both models and was inversely correlated with CD99 expression. STATHMIN was identified in the A20 cell line model and its expression was positively correlated with that of CD99. Importantly, silencing of SEPTIN2 with siRNA substantially altered the cellular cytoskeleton in L428 cells. The downregulation of STATHMIN by siRNA promoted the differentiation of H/RS cells toward terminal B-cells. These results suggest that SEPTIN2-mediated cytoskeletal rearrangement and STATHMIN-mediated differentiation may contribute to changes in cell morphology and differentiation of H/RS cells with CD99 upregulation in HL.

Expression of Septin4 in Schistosoma japonicum-infected mouse livers after praziquantel treatment

Background

Septin4 (SEPT4) exists widely in human tissues and is related to mechanical stability, actin dynamics, membrane trafficking, viral replication and apoptosis. Data from many studies have suggested that SEPT4 plays a significant role in liver fibrosis. SEPT4 is down-regulated in the model of CCl₄ and BDL treated liver fibrosis. However, it is up-regulated and peaked at 12 weeks post-infection (p.i.), and then decreased subsequently in Schistosoma japonicum (S. japonicum) egg-induced liver fibrosis. The aim of this study was to observe the dynamic alteration of SEPT4 after the treatment of praziquantel (PZQ) in ICR mice infected with S. japonicum.

Methods

Expression of SEPT4 was determined by western blot, immunofluorescence and qRT-PCR. And pro-inflammatory cytokines IL-6 and TNF-α were detected by qRT-PCR. The number of eggs, the diameter of egg granulomas and fibrosis-associated genes were also measured.

Results

Our results showed that the granulomatous inflammation was reduced, whereafter the expression of SEPT4 on hepatic stellate cells (HSCs) was decreased after PZQ anti-schistosome therapy. And the variation tendency of SEPT4 had positive correlation with the inflammatory response in the area of S. japonicum egg granulomas.

Conclusions

Based on these findings, the inhibition of the expression of the SEPT4 by PZQ might be due to alleviation of the inflammatory response at the chronic and advanced stage of S. japonicum infection.