PML nuclear bodies and SATB1 are associated with HLA class I expression in EBV+ Hodgkin lymphoma

SATB1 and p16 Expression and Prognostic Value in Croatian Hodgkin Lymphoma Patients: A Unicentric Study

Hodgkin lymphoma (HL) is a rare lymphoid neoplasm in which Hodgkin/Reed-Stenberg (HRS) cells are admixed with a population of non-neoplastic inflammatory cells and fibrosis. Dysregulated expressions of cell cycle regulators and transcription factors have been proven as one of the hallmarks of HL. In that context, SATB1 and p16 have been reported as potential regulators of HL progression and survival. However, to date, no studies have assessed the expression levels of SATB1 and p16 in HL in Croatian patients or their prognostic values. Therefore, we investigated the expression pattern of SATB1 and p16 in paraffin-embedded lymph node biopsies using standard immunohistochemistry. We found that 21% of the patients stained positive for SATB1, while 15% of the patients displayed positive staining for p16. Furthermore, we aimed to understand the prognostic value of each protein through the analysis of the overall survival (OS) and progression-free survival (PFS). SATB1 showed a significantly positive correlation with better OS and PFS, while p16 expression had no impact. Interestingly, when patients were stratified by a combination of the two studied markers, we found that patients in the SATB1+/p16- group tended to have the best prognosis in HL, according to statistical significance. In conclusion, SATB1 and p16 might be potentially useful as diagnostic and prognostic markers for HL.

The Microenvironment in Epstein-Barr Virus-Associated Malignancies

The Epstein–Barr virus (EBV) can cause a wide variety of cancers upon infection of different cell types and induces a highly variable composition of the tumor microenvironment (TME). This TME consists of both innate and adaptive immune cells and is not merely an aspecific reaction to the tumor cells. In fact, latent EBV-infected tumor cells utilize several specific mechanisms to form and shape the TME to their own benefit. These mechanisms have been studied largely in the context of EBV+ Hodgkin lymphoma, undifferentiated nasopharyngeal carcinoma, and EBV+ gastric cancer. This review describes the composition, immune escape mechanisms, and tumor cell promoting properties of the TME in these three malignancies. Mechanisms of susceptibility which regularly involve genes related to immune system function are also discussed, as only a small proportion of EBV-infected individuals develops an EBV-associated malignancy.

Tetramerization of SATB1 is essential for regulating of gene expression

Special AT-rich sequence-binding protein 1 (SATB1) functions as a 'genome organizer' in tumorigenesis. Our previous report showed that SATB1 forms a tetramer through its N-terminal ubiquitin like domain rather than the proposed PDZ domain. In the present study, we aim to illustrate whether this oligomerization is critical to its function as a global repressor of gene expression in vivo. Luciferase and GST pull-down assays demonstrated that disrupting SATB1's tetramerization not only affects the activities of promoters but also influences the recruitment of interaction partners. Furthermore, we developed stable cell lines that overexpressed either the SATB1 tetramer or STAB1 dimer (KWN-AAA) and monitored global gene expression. Gene expression profiling revealed that over 1000 genes were significantly upregulated or downregulated upon the overexpression of SATB1 or the SATB1 (KWN-AAA) mutant. These data implied that SATB1 might regulate gene expression through its different oligomerization state. In conclusion, we inferred that the oligomerization of SATB1 is pivotal to its function of different biological processes.

Special AT-rich DNA-binding protein-1 expression is associated with liver cancer metastasis

To aim of the present study was to investigate the association between special AT-rich DNA-binding protein-1 (SATB1) expression and liver cancer metastasis. SATB1 mRNA and protein expression in hepatocellular carcinoma tissues was analyzed by immunohistochemistry, and in two hepatocellular cancer cell lines, MHCC-97H (high metastatic potential) and HepG2 (low metastatic potential), by reverse transcription-polymerase chain reaction and western blot analysis. Transwell migration and wound-healing assays were also performed to investigate the metastasis of liver cancer following upregulation or silencing of SATB1 expression. The results revealed that SATB1 expression was significantly higher in hepatocellular carcinoma tissues compared with carcinoma-adjacent tissues. Furthermore, SATB1 expression was correlated with tumor size, differentiation degree, hemorrhage and/or necrosis, invasion and/or metastases and TNM stage. Both the mRNA and protein expression of SATB1 was higher in MHCC-97H cells than HepG2 cells. In addition, the migration capability of MHCC-97H cells was decreased after SATB1 silencing, whereas the migration capability of HepG2 cells was increased after SATB1 upregulation. SATB1 expression was demonstrated to be positively correlated with liver cancer metastasis. These results indicate that liver cancer metastasis is regulated by SATB1 expression. Thus, immunohistochemical SATB1 expression may present an independent risk factor for the metastasis of liver cancer.

T-Cell Responses to EBV

Epstein-Barr virus (EBV) is arguably one of the most successful pathogens of humans, persistently infecting over ninety percent of the world's population. Despite this high frequency of carriage, the virus causes apparently few adverse effects in the vast majority of infected individuals. Nevertheless, the potent growth transforming ability of EBV means the virus has the potential to cause malignancies in infected individuals. Indeed, EBV is thought to cause 1% of human malignancies, equating to 200,000 malignancies each year. A clear factor as to why virus-induced disease is relatively infrequent in healthy infected individuals is the presence of a potent immune response to EBV, in particular, that mediated by T cells. Thus, patient groups with immunodeficiencies or whose cellular immune response is suppressed have much higher frequencies of EBV-induced disease and, in at least some cases, these diseases can be controlled by restoration of the T-cell compartment. In this chapter, we will primarily review the role the αβ subset of T cells in the control of EBV in healthy and diseased individuals.