High concentration of γ­H2AX correlates with a marker of apoptotic suppression and PI3K/Akt pathway upregulation in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is a very aggressive type of primary brain tumor in adults with a poor prognosis. DNA double-strand breaks are known to be associated with the development of numerous cancer types due to their ability to generate genomic instabilities. In GBM, the phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a common pathway that can be activated by exogenous and endogenous factors. Genomic instability may be an endogenous stimulating factor for activation of the PI3K/Akt pathway, which may inhibit the apoptosis of GBM cells. Spontaneous DNA double-strand breaks play an essential role in the survival of GBM cells, and apoptosis levels may reflect survival ability. However, no study has yet been conducted to analyse the association between spontaneous DNA double-strand breaks and apoptosis in patients with GBM prior to treatment. Therefore, the present study examined the concentrations of γ-histone 2AX (γ-H2AX), a sensitive marker of spontaneous DNA double-strand breaks, and cleaved caspase-3, a marker of apoptosis, in patients with GBM. The correlation of γ-H2AX with cleaved caspase-3, PI3K and Akt was also investigated. A total of 26 pre-treatment tumor tissue specimens from patient with GBM were analyzed to determine the concentrations of γ-H2AX, PI3K, Akt and cleaved caspase-3 using sandwich enzyme-linked immunosorbent assays. The results showed a moderate positive correlation between γ-H2AX and PI3K (r=0.52; P=0.007), a moderate positive correlation between γ-H2AX and Akt (r=0.4; P=0.041) and a strong negative correlation between γ-H2AX and cleaved caspase-3 (r=-0.61; P=0.0009). These analyses were also performed in seven tumor tissue specimens from patients with grade I glioma as controls, but no significant correlations were detected. The findings of the present study suggest that a high level of γ-H2AX may affect GBM cell apoptosis via the PI3K/Akt pathway.

Immune cells markers within local tumor microenvironment are associated with EBV oncoprotein in nasopharyngeal cancer.

INTRODUCTION: EBV infection in nasopharyngeal cancer ensued in latent infection mode. In this latent infection various EBV oncoproteins such as EBNA1 and LMP1 was expressed. EBV oncoproteins could theoretically recruit immune cells, which might help to control cancer. Therefore, this study was aimed to elucidate the association with EBV oncoproteins (EBNA1 and LMP1), immune markers (CD4, CD8, and FOXP3) from nasopharyngeal cancer microenvironment with tumor progression. METHOD: Nasopharyngeal biopsy was obtained from patients suspected to have nasopharyngeal cancer. Those samples with microscopically confirmed nasopharyngeal cancer were tested for EBNA1, LMP1, CD4, CD8, and FOXP3 concentration with ELISA, then verified with IHC. Each patient tumor volume was assessed for primary nasopharyngeal tumor volume (GTVp) and neck nodal metastases tumor volume (GTVn). Correlation test with Spearman correlation and scatterplot were carried out. RESULT: Total 23 samples with nasopharyngeal cancer were analyzed. There was moderate correlation (ρ = 0.45; p value = 0.032) between LMP1 and GTVp. There was strong correlation (ρ = 0.81; p value < 0.001) between CD8 and GTVp. There was also moderate correlation (ρ = 0.6; p value = 0.002) between FOXP3 and GTVp. The CD8 concentration has moderate correlation with both EBNA1 (ρ = 0.46; p value = 0.026) and LMP1 (ρ = 0.47; p value = 0.023). While FOXP3 has moderate correlation with only LMP1 (ρ = 0.58; p value = 0.004). No correlation was found between all the markers tested here with GTVn. DISCUSSION: We found larger primary nasopharyngeal tumor was associated with higher CD8 marker. This was thought due to the presence of abundance CD8 T cells in the nasopharynx, but those abundance CD8 T cells were suspected to be dysfunctional. The nasopharyngeal cancer was also known to upregulate chemokines that could recruit T regulatory FOXP3 cells. Furthermore, T regulatory FOXP3 cells differentiation was induced through several pathways which was triggered by EBNA1. The correlation found in this study could guide further study to understand nasopharyngeal carcinogenesis and the relationship with our immune system.

Role of CD4+CD25+FOXP3+ TReg cells on tumor immunity.

Not all T cells are effector cells of the anti-tumor immune system. One of the subpopulations of CD4+ T cells that express CD25+ and the transcription factor FOXP3, known as Regulator T cells (TReg), plays an essential role in maintaining tolerance and immune homeostasis preventing autoimmune diseases, minimalize chronic inflammatory diseases by enlisting various immunoregulatory mechanisms. The balance between effector T cells (Teff) and regulator T cells is crucial in determining the outcome of an immune response. Regarding tumors, activation or expansion of TReg cells reduces anti-tumor immunity. TReg cells inhibit the activation of CD4+ and CD8+ T cells and suppress anti-tumor activity in the tumor microenvironment. In addition, TReg cells also promote tumor angiogenesis both directly and indirectly to ensure oxygen and nutrient transport to the tumor. There is accumulating evidence showing a positive result that removing or suppressing TReg cells increases anti-tumor immune response. However, depletion of TReg cells will cause autoimmunity. One strategy to improve or restore tumor immunity is targeted therapy on the dominant effector TReg cells in tumor tissue. Various molecules such as CTLA-4, CD4, CD25, GITR, PD-1, OX40, ICOS are in clinical trials to assess their role in attenuating TReg cells' function.