Yongyu Shi

Down-regulation of TIPE2 mRNA expression in peripheral blood mononuclear cells from patients with systemic lupus erythematosus

Breakdown of immune homeostasis contributes to the pathogenesis of systemic lupus erythematosus (SLE). Tumor necrosis factor alpha induced protein-8 like-2 (TIPE2) is a very recently identified immune homeostasis maintaining gene. We wondered whether TIPE2 is associated with SLE. We examined the mRNA expression levels of TIPE2 and myxoma resistance protein (MX) 1 (one of type I interferon inducible genes) in peripheral blood mononuclear cells (PBMC) from 39 SLE patients and 35 healthy controls by real-time reverse transcription-polymerase chain reaction analysis (RT-PCR). The TIPE2 mRNA expression was significantly down-regulated in SLE patients compared with healthy controls (P=0.0004), while the MX1 mRNA expression was increased in SLE patients compared with healthy controls (P=0.0031). Furthermore, the TIPE2 mRNA expression levels negatively correlate with the SLE disease activity index (SLEDAI) (r=-0.5016, P=0.0011) and the MX1 mRNA expression levels (r=-0.8083, P<0.0001) in all the SLE patients. These results indicate that decreased expression of TIPE2 gene is closely associated with SLE and suggest an important role for TIPE2 gene in the pathogenesis of SLE.

IL-17 induces apoptosis of vascular endothelial cells — A potential mechanism for human acute coronary syndrome

Th17 cells producing IL-17 are involved in the pathogenesis of atherosclerosis, but the underlying mechanisms remain unclear. In this study, we investigated the effects of IL-17 on human vascular endothelial cells and showed that IL-17 induced cell death of the vascular endothelial cells, which played a pivotal role in plaque destabilization triggering acute coronary syndrome (ACS). We showed that circulating Th17 cells and IL-17 increased in patients with ACS compared to the patients with stable angina or health individuals; the plasma levels of IL-6 increased but TGF-β decreased in ACS patients, exhibiting a positive and negative correlation with that of IL-17, respectively. Importantly, we uncovered that IL-17 promoted the production of von Willebrand factor by endothelial cells and induced endothelial apoptosis by activating caspase-3, caspase-9 and up-regulating the ratio of Bax/Bcl-2, indicating the function of IL-17 in vascular endothelial damage as a potential mechanism for the pathogenesis of human ACS.

Hepatitis B virus core protein inhibits TRAIL-induced apoptosis of hepatocytes by blocking DR5 expression

Hepatitis B virus (HBV) causes chronic hepatitis in hundreds of millions of people worldwide, which can eventually lead to hepatocellular carcinoma (HCC). The molecular mechanisms underlying HBV persistence are not well understood. TRAIL, the TNF-related apoptosis-inducing ligand, has recently been implicated in hepatocyte death during HBV infection. We report here that the HBV core protein (HBc) is a potent inhibitor of TRAIL-induced apoptosis. Overexpressing HBc significantly decreased TRAIL-induced apoptosis of human hepatoma cells, whereas knocking-down HBc expression in hepatoma cells transfected with HBV genome enhanced it. When present in the same cell, HBc blocked the pro-apoptotic effect of the HBV X protein (HBx). The resistance of HBc-expressing cells to TRAIL-induced apoptosis was associated with a significant reduction in death receptor 5 (DR5) expression. Upon transfection, HBc significantly repressed the promoter activity of the human DR5 gene. Importantly, HBc gene transfer inhibited hepatocyte death in a mouse model of HBV-induced hepatitis; and in patients with chronic hepatitis, DR5 expression in the liver was significantly reduced. These results indicate that HBc may prevent hepatocytes from TRAIL-induced apoptosis by blocking DR5 expression, which in turn contributes to the development of chronic hepatitis and HCC. They also call into question the potential side effects of HBc-based vaccines.

Upregulation of B7-H1 expression is associated with macrophage infiltration in hepatocellular carcinomas

The overexpression of B7-H1 in hepatocellular carcinoma (HCC) mediates HCC immune escape and obstructs the immunotherapy based on tumor-specific CD8+ T cells. Tumor-associated macrophages (TAM) are a major component of cancer-related inflammation and play a central role in tumor promotion. To classify the mechanism underlying the overexpression of B7-H1 in HCC, we examined B7-H1 expression and TAM infiltration in 63 cases of human HCC samples using immunohistochemistry method and found that B7-H1 overexpression was associated with TAM infiltration in HCC tissues. Furthermore, B7-H1 expression was upregulated at both mRNA level and protein level in HCC cells (BEL-7402 and SMMC-7721) cocultured with macrophages in a transwell system. The upregulation of B7-H1 expression induced by macrophage was inhibited by blocking NF-κB or STAT3 signal pathways. These results suggest that overexpression of B7-H1 in HCC may be induced by inflammatory microenvironment involving macrophages and imply that anti-inflammation therapy might be preventive for immune escape and assistant for immunotherapy of HCC.

The unique expression profile of human TIPE2 suggests new functions beyond its role in immune regulation

TIPE2 (tumor necrosis factor-α-induced protein 8-like 2, or TNFAIP8L2) is a newly identified negative regulator of innate and adaptive immunity. TIPE2 deficiency in mice leads to systemic inflammation and TIPE2 down-regulation in humans is associated with autoimmunity. However, the nature of human TIPE2-expressing cells in various tissues has not been characterized due to the lack of suitable antibodies. In the present study, we generated specific rabbit antibodies against human TIPE2 and examined human TIPE2 expression in various tissues by Western blot, flow cytometry, and immunohistochemistry. We found that unlike murine TIPE2 that is preferentially expressed by hematopoietic cells, human TIPE2 was also expressed in a wide variety of non-hematopoietic cell types, including hepatocytes, neurons in brain and brainstem, squamous epithelial cells in esophagus and cervix, transitional epithelial cells in bladder and ureter, and glandular epithelial cells in stomach, colon and appendix. For squamous epithelium, the level of TIPE2 expression increased dramatically in terminally differentiated cells with the proliferating precursor cells completely devoid of TIPE2. The unique expressional profile of human TIPE2 suggests new functions beyond controlling innate and adaptive immunity.

Human tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 suppresses hepatocellular carcinoma metastasis through inhibiting Rac1.

BackgroundTumor invasion and metastasis are the major reasons for leading death of patients with hepatocellular carcinoma (HCC). Therefore, to identify molecules that can suppress invasion and metastasis of tumor will provide novel targets for HCC therapies. Tumor necrosis factor (TNF)-alpha-induced protein 8-like 2, TIPE2, is a novel immune negative molecule and an inhibitor of the oncogenic Ras in mice but its function in human is unclear. Our previous research has shown that TIPE2 is downregulated in human primary HCC compared with the paired adjacent non-tumor tissues.ResultsIn present study, we provide evidence that TIPE2 inhibits effectively human hepatocellular carcinoma metastasis. The forced expression of TIPE2 in HCC-derived cell lines markedly inhibits tumor cell growth, migration and invasion in vitro and suppresses growth and metastasis of HCC in vivo. Clinical information from a cohort of 112 patients reveals that loss or reduced expression of TIPE2 in primary HCC tissues is significantly associated with tumor metastasis. Mechanically, TIPE2 inhibits the migration and invasion through targeting Rac1 and then reduces F-actin polymerization and expression of matrix metallopeptidase 9 (MMP9) and urokinase plasminogen activator (uPA).ConclusionOur results indicate that human TIPE2 is endogenous inhibitor of Rac1 in HCC by which it attenuates invasion and metastasis of HCC. The data suggest that TIPE2 will be a new target for HCC therapy.

Tumor suppressor gene PDCD4 negatively regulates autophagy by inhibiting the expression of autophagy-related gene ATG5

PDCD4 (programmed cell death protein 4), a suppressor of gene transcription and translation, plays a crucial inhibitory role in several types of human tumors. However, its underlying mechanisms remain unclear. Autophagy, an evolutionarily conserved catabolic process, maintains cellular homeostasis under stress conditions such as starvation and plays a crucial role in tumor initiation and progression. We report here that PDCD4 inhibits autophagy in multiple cell types both in vitro and in vivo, which in turn contributes to its tumor suppressor activity. Importantly, PDCD4 inhibits the expression of an essential autophagy related gene, ATG5 and the formation of an ATG12–ATG5 complex, and its ma3 domains are required for PDCD4-mediated inhibition of autophagy. Unlike most tumor suppressors that act as positive or dual regulators of autophagy, our findings indicate that PDCD4 negatively regulates autophagy by targeting ATG5, which provides a novel mechanism of tumor suppression.

Programmed cell death 4 enhances chemosensitivity of ovarian cancer cells by activating death receptor pathway in vitro and in vivo

Chemoresistance is a major cause of treatment failure in ovarian cancer. Therefore, it is necessary to explore alternative therapeutic methods to overcome drug resistance for ovarian cancer treatment. We previously reported that programmed cell death 4 (PDCD4), a tumor suppressor, significantly suppresses the malignant phenotype of ovarian cancer cells and its lost or low expression in ovarian cancer is associated with unfavorable prognosis of patients. Here we show that PDCD4 improves the sensitivity of ovarian cancer cells to platinum‐based chemotherapy. Overexpression of PDCD4 enhanced chemosensitivity in SKOV3 and CAOV3 cells with low levels of PDCD4, whereas knockdown of PDCD4 reduced chemosensitivity in OVCAR3 cells with high levels of PDCD4. Subsequently, the combination of enforced PDCD4 expression with cisplatin treatment significantly suppressed ovarian tumor growth in a xenograft animal model. The PDCD4 effect appears to be specific for cisplatin and carboplatin, not affecting cyclophosphamide, etoposide, or paclitaxel. Mechanistically, PDCD4 significantly increased cisplatin‐induced cleavage of caspase‐3 and caspase‐8, but had only a slight impact on caspase‐9 cleavage and the expression of Bax and Bcl‐2 in vitro and in vivo. A specific caspase‐8 inhibitor, Z‐ITED‐FMK, attenuated cisplatin‐induced apoptosis in PDCD4‐overexpressing ovarian cancer cells. Taken together, our results indicate that PDCD4 enhances cisplatin‐induced apoptosis by mainly activating the death receptor pathway, and PDCD4 gene transfer in combination with cisplatin therapy may break the resistance of ovarian cancer cells to chemotherapy. (Cancer Sci 2010)

CD68(+)HLA-DR(+) M1-like macrophages promote motility of HCC cells via NF-κB/FAK pathway.

TAM is a prominent component of inflammatory microenvironment, presenting M1 and M2 polarized states in HCC. The objective of this study is to investigate the relationship between M1-polarized macrophages and metastasis in HCC. We used immunohistochemical double-staining method to inspect the infiltration of CD68(+)HLA-DR(+) M1-like macrophages in HCC tissues. The M1-polarized macrophage was derived from THP-1 cell treated by LPS and IFN-γ in vitro. Transwell migration assay was used to evaluate whether the M1-polarized macrophage enhanced motility of HCC cells in the presence or absence of NF-κB inhibitor Bay 11-7802. The activation of NF-κB and FAK signaling pathways was examined by Western blot assay. Our results showed that the density of CD68(+)HLA-DR(+) TAM in the HCC with metastasis is significantly higher than that in the HCC without metastasis. Moreover, the conditioned medium from the M1 macrophages promote the migration of HCC cells and induced the activation of NF-κB and FAK signaling. The promoted migration of HCC cells was abrogated by the Bay 11-7802, as well as the activation of NF-κB and FAK pathway. Our findings implied a pro-metastatic role of M1-like TAM in HCC.

Down-Regulation of A20 mRNA Expression in Peripheral Blood Mononuclear Cells from Patients with Systemic Lupus Erythematosus

PurposeA20 gene functions in negative immunoregulation and its SNP is related to SLE disease. But its expression level in immune cells from SLE patients is still unclear. The aim of this study is to investigate whether the expression of A20 is associated with pathogenesis of SLE.MethodsReal-time transcription-polymerase chain reaction analysis (RT-PCR) was used to determine expression of A20 mRNA in peripheral blood mononuclear cells (PBMC) from 37 patients with SLE and 32 healthy controls.ResultsA20 expression was decreased in SLE patients compared with healthy controls (p = 0.0133). The expression level of A20 gene negatively correlated with the SLE disease activity index (SLEDAI) (r =−0.4661, p = 0.0036) and erythrocyte sedimentation rate (ESR) (r =−0.5222, p = 0.0009). Furthermore, SLE patients with nephritis had a lower expression of A20 than those without nephritis (p = 0.0188).ConclusionsOur results suggest that the insufficient expression of A20 gene in PBMC may take part in the pathogenesis of SLE disease.