Autophagy, an evolutionarily conserved process by which components of the cell are degraded in lysosomes, may facilitate survival of cancer cells under stress conditions. 8-Azaguanine (8-AG), an inhibitor of purine nucleotide biosynthesis, shows antineoplastic activity in multiple tumor cells. However, chemoresistance has restricted its development as an anticancer agent, and the mechanism of 8-AG resistance is not fully understood. We report here that 8-AG induces a protective autophagy to eliminate its cytotoxicity, and inhibition of autophagy increases cellular sensitivity of cancer cells to 8-AG treatment. Using HepG2 or SMMC-7721 hepatic cancer cell lines, we found that 8-AG inhibited cell viability and induced intrinsic apoptosis, accompanied by the up-regulation of the pro-apoptotic protein BimS, one of Bim (also known as BCL-2-like protein 11, BCL2L11) isoforms. Furthermore, 8-AG treatment enhanced the autophagy flux by promoting the dephosphorylation and activation of Unc-51-like autophagy activating kinase 1 (ULK1) via Akt/mTORC1 (mammalian target of rapamycin complex 1) signaling inhibition. Depletion of autophagy-related gene 7 (ATG7) markedly enhanced the level of BimS, and promoted cell death in response to 8-AG. 8-AG in combination with autophagy inhibitor chloroquine (CQ) or bafilomycin A1 (Baf A1) promoted the 8-AG-induced apoptosis in hepatic cancer cells. Altogether, these findings suggest that autophagy promotes chemoresistance of cancer cells for 8-AG, and blocking autophagy increases cellular sensitivity of cancer cells to 8-AG treatment.

OBJECTIVE: To investigate the phenolic composition, antioxidant properties, and hepatoprotective mechanisms of polyphenols from green tea extract (GTP) in carbon tetrachloride (CCl)-induced acute liver injury mouse model. METHODS: High-performance liquid chromatography was used to analyze the chemical composition of the extract. Antioxidant activity of GTP was assessed by O, OH, DPPH, and ferric-reducing antioxidant power (FRAP) assay in vitro. Sixty Kunming mice were divided into 6 groups including control, model, low-, medium-, and high-doses GTP (200, 400, 800 mg/kg) and vitamin E (250 mg/kg) groups, 10 in each group. GTP and vitamin E were administered at a level of abovementioned doses twice per day for 7 days prior to exposure to a single injection of CCl. Hepatoprotective effects of GTP were evaluated in a CCl-induced mouse model of acute liver injury, using commercial enzyme linked immunosorbent assay kits, histopathological observation, terminal deoxynucleotidyl transferase-mediated dUTPNick-end labeling (TUNEL) assay and Western blot. RESULTS: GTP contained 98.56 µg gallic acid equivalents per milligram extract total polyphenols, including epicatechingallate, epigallocatechin gallate, epicatechin, and epigallocatechin. Compared with the model group, low-, medium-, or high doses GTP significantly decreased serum levels of alanine aminotransferase and aspartate transaminase (P<0.01). Histopathological observation confirmed that pretreatment of GTP prevented swelling and necrosis in CCl-exposed hepatocytes. Hepatoprotective effects of low-, medium-, and high-dose GTP were associated with eliminating free radicals and improving superoxide dismutase, catalase, and glutathione peroxidase activity in the liver. Additionally, low-, medium-, and high-dose GTP decreased cell apoptosis in the CCl-exposed liver (P<0.01). Phosphorylated nuclear factor kappa-B (NF-κB), p53, Bcl-2 associated x protein/B-cell lymphoma/leukemia-2 gene, cytochrome C, and cleaved caspase-3 levels were downregulated compared with the model group (P<0.01). CONCLUSION GTP achieves hepatoprotective effects by improving hepatic antioxidant status and preventing cell apoptosis through caspase-3-dependent signaling pathways.

OBJECTIVE: To analyze the clinicopathological features, molecular changes and prognostic factors in angioimmunoblastic T-cell lymphoma (AITL). METHODS: Sixty-one cases AITL diagnosed by Department of Pathology of Peking University Cancer Hospital were collected with their clinical data. Morphologically, they were classified as typeⅠ[lymphoid tissue reactive hyperplasia (LRH) like]; typeⅡ[marginal zone lymphoma(MZL)like] and type Ⅲ [peripheral T-cell lymphoma, not specified (PTCL-NOS) like]. Immunohistochemical staining was used to evaluate the presence of follicular helper T-cell (TFH) phenotype, proliferation of extra germinal center (GC) follicular dendritic cells (FDCs), presence of Hodgkin and Reed-Sternberg (HRS)-like cells and large B transformation. The density of Epstein-Barr virus (EBV) + cells was counted with slides stained by Epstein-Barr virus encoded RNA (EBER) in situ hybridization on high power field (HPF). T-cell receptor / immunoglobulin gene (TCR/IG) clonality and targeted exome sequencing (TES) test were performed when necessary. SPSS 22.0 software was used for statistical analysis. RESULTS: Morphological subtype (%): 11.4% (7/61) cases were classified as type Ⅰ; 50.8% (31/61) as type Ⅱ; 37.8% (23/61) as type Ⅲ. 83.6% (51/61) cases showed classical TFH immunophenotype. With variable extra-GC FDC meshwork proliferation (median 20.0%); 23.0% (14/61) had HRS-like cells; 11.5% (7/61) with large B transformation. 42.6% (26/61) of cases with high counts of EBV. 57.9% (11/19) TCR⁺/IG^-, 26.3% (5/19) TCR⁺/IG⁺, 10.5% (2/19) were TCR^－/IG^－, and 5.3% (1/19) TCR^－/IG⁺. Mutation frequencies by TES were 66.7% (20/30) for RHOA, 23.3% (7/30) for IDH2 mutation, 80.0% (24/30) for TET2 mutation, and 33.3% (10/30) DNMT3A mutation. Integrated analysis divided into four groups: (1) IDH2 and RHOA co-mutation group (7 cases): 6 cases were type Ⅱ, 1 case was type Ⅲ; all with typical TFH phenotype; HRS-like cells and large B transformation were not found; (2) RHOA single mutation group (13 cases): 1 case was type Ⅰ, 6 cases were type Ⅱ, 6 cases were type Ⅲ; 5 cases without typical TFH phenotype; 6 cases had HRS-like cells, and 2 cases with large B transformation. Atypically, 1 case showed TCR^－/IG^－, 1 case with TCR^－/IG⁺, and 1 case with TCR⁺/IG⁺; (3) TET2 and/or DNMT3A mutation alone group (7 cases): 3 cases were type Ⅱ, 4 cases were type Ⅲ, all cases were found with typical TFH phenotype; 2 cases had HRS-like cells, 2 cases with large B transformation, and atypically; (4) non-mutation group (3 cases), all were type Ⅱ, with typical TFH phenotype, with significant extra-GC FDC proliferation, without HRS-like cells and large B transformation. Atypically, 1 case was TCR^－/IG^－. Univariate analysis confirmed that higher density of EBV positive cell was independent adverse prognostic factors for both overall survival (OS) and progression free survival(PFS), (P=0.017 and P=0.046). CONCLUSION Pathological diagnoses of ALTL cases with HRS-like cells, large B transformation or type Ⅰ are difficult. Although TCR/IG gene rearrangement test is helpful but still with limitation. TES involving RHOA, IDH2, TET2, DNMT3A can robustly assist in the differential diagnosis of those difficult cases. Higher density of EBV positive cells counts in tumor tissue might be an indicator for poor survival.
Humans ; Epstein-Barr Virus Infections/genetics* ; Herpesvirus 4, Human/genetics* ; T-Lymphocytes, Helper-Inducer/pathology* ; Immunoblastic Lymphadenopathy/pathology* ; Lymphoma, T-Cell, Peripheral/pathology* ; Receptors, Antigen, T-Cell