Impact of X-linked inhibitor of apoptosis protein on survival of nasopharyngeal carcinoma patients following radiotherapy

Evasion of apoptosis and treatment resistance in squamous cell carcinoma of the head and neck

Combinations of surgery, radiotherapy and chemotherapy can eradicate tumors in patients with locally advanced squamous cell carcinoma of the head and neck (LA SCCHN), but a significant proportion of tumors progress, recur, or do not respond to therapy due to treatment resistance. The prognosis for these patients is poor, thus new approaches are needed to improve outcomes. Key resistance mechanisms to chemoradiotherapy (CRT) in patients with LA SCCHN are alterations to the pathways that mediate apoptosis, a form of programmed cell death. Targeting dysregulation of apoptotic pathways represents a rational therapeutic strategy in many types of cancer, with a number of proteins, including the pro-survival B-cell lymphoma 2 family and inhibitors of apoptosis proteins (IAPs), having been identified as druggable targets. This review discusses the mechanisms by which apoptosis occurs under physiological conditions, and how this process is abnormally restrained in LA SCCHN tumor cells, with treatment strategies aimed at re-enabling apoptosis in LA SCCHN also considered. In particular, the development of, and future opportunities for, IAP inhibitors in LA SCCHN are discussed, in light of recent encouraging proof-of-concept clinical trial data.

Subcellular localization of X-linked inhibitor of apoptosis protein (XIAP) in cancer: does that matter?

X-linked inhibitor of apoptosis protein (XIAP) finely tunes the balance between survival and death to control homeostasis. XIAP is found aberrantly expressed in cancer, which has been shown to promote resistance to therapy-induced apoptosis and confer poor outcome. Despite its predominant cytoplasmic localization in human tissues, growing evidence implicates the expression of XIAP in other subcellular compartments in sustaining cancer hallmarks. Herein, we review our current knowledge on the prognostic role of XIAP localization and discuss molecular mechanisms underlying differential biological functions played in each compartment. The comprehension of XIAP subcellular shuttling and functional dynamics might provide the rationale for future anticancer therapeutics.

Brucella Outer Membrane Lipoproteins 19 and 16 Differentially Induce IL-18 Response or Pyroptosis in Human Monocytic Cells

BACKGROUND

Brucella species (B. spp.) are Gram-negative intracellular bacteria, causing severe inflammatory diseases in animals and humans. Two major lipoproteins (L19) and (L16) of Brucella outer membrane proteins (OMPs) were extensively explored in associating with inflammatory response of human monocytes (THP-1).

METHODS

Activated THP-1 cells induced with recombinant L19 and L16 were analyzed in comparison with unlipidated forms (U19 and U16) and lipopolysaccharide (LPS) of B. melitensis, respectively.

RESULTS

Secretion of inflammatory factors TNF-α, IL-6 and IL-1β was significantly increased from L19, L16 or both stimulated THP-1 cells. High secretion of IL-18 was detected only from L19-induced cells. Signaling of those cytokine responses was identified mainly through P38-MAPK pathway, and signaling of L19-induced IL-1β response was partly occurred via NF-κB. Exploration for different forms of IL-18 found that L19-induced production of active IL-18 (18 kD) was through up-regulating NLRP3 and activating caspase-1, while L16-induced production of inactive IL-18 fragments (15 kD and 16 kD) occurred through activating caspase-8/3. Additionally, L19 up-regulated phosphorylation of XIAP for inhibiting caspase-3 activity to cleave IL-18, while L16 activated caspase-3 for producing GSDME-N and leading to pyroptosis of THP-1 cells.

CONCLUSION

Brucella L19 and L16 differentially induce IL-18 response or pyroptosis in THP-1 cells, respectively.

[Effect of stable overexpression of XAF1 gene on biological characteristics of ovarian cancer A2780 cells]

OBJECTIVE

To construct an ovarian cancer cell line stably overexpressing XAF1 gene and observe the effects of XAF1 gene overexpression on proliferation, apoptosis, cell cycle and sensitivity to paclitaxel of the cells.

OBJECTIVE

Ovarian cancer A2780 cells were transfected with the plasmids pcDNA3.1(+) or pcDNA3.1(+)-XAF1, and the cells stably Over expressing XAF1 (A2780/XAF1 cells) were screened using G418. Cell clone formation assay and CCK8 assay were used to evaluate the changes in proliferation and paclitaxel sensitivity of the transfected cells, and cell cycle and apoptosis of the cells were analyzed using flow cytometry.

OBJECTIVE

We successfully obtained A2780/XAF1 cells stably overexpressing XAF1, which exhibited no significant changes in cell morphology. Compared with the negative control cells (A2780/NC), A2780/XAF1 cells had lowered clone formation ability (P=0.0016) and attenuated proliferative activity on the first (P=0.009) and third (P=0.0035) days after cell adherence with also a significantly increased percentage of cells in G2-M phase (P < 0.001). A2780/XAF1 cells showed significantly higher apoptosis rates than A2780/NC cells in the absence of apoptotic stimulation, in serum-free culture or following paclitaxel induction (P < 0.001). The proliferative activity of A2780/XAF1 cells was significantly lower than that of A2780/NC cells after exposure to different paclitaxel concentrations (P < 0.001). The half inhibitory concentration of paclitaxel was significantly lower in A2780/XAF1 than in A2780/NC cells.

OBJECTIVE

Overexpression of XAF1 significantly inhibits the proliferation, induces cell cycle arrest, promotes apoptosis, and increases paclitaxel sensitivity in ovarian cancer cells.

Isoimperatorin Induces Apoptosis of Nasopharyngeal Carcinoma Cells via the MAPK/ERK1/2 Signaling Pathway

Objective

To investigate the effect of isoimperatorin on nasopharyngeal carcinoma CNE2 cell apoptosis and the role of the MAPK/ERK1/2 signaling pathway in inducing apoptosis.

Methods

Real-time cellular analysis technology (RTCA) and MTT were used to detect cell proliferation; Annexin V-FITC/PI dual-fluorescence flow cytometry analysis, Hoechst 33342 staining, and mitochondrial membrane potential detection kit were used to detect cell apoptosis; western blot was used to detect protein expression.

Results

Different concentrations of isoimperatorin (10 μM, 20 μM, 20 μM, 20 μM, 20 μM, 20 μM, 20 μM, 20 

Conclusion

Isoimperatorin can induce nasopharyngeal carcinoma CNE2 cell apoptosis through the MAPK/ERK1/2 signaling pathway.

Prognostic Value of XIAP Level in Patients with Various Cancers: A Systematic Review and Meta-Analysis

Background: X-linked inhibitor of apoptosis protein (XIAP) plays an important role in cancer pathogenesis, which has been found to be overexpressed in multiple human cancers and associated with survival rates. Herein, we performed a meta-analysis to explore the predictive value of XIAP level in patients with various solid tumors. Methods: Relevant articles exploring the relationship between XIAP expression and survival of cancer patients were retrieved in PubMed, PMC, EMBASE and Web of Science published from 2001 to 2018. The combined hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to evaluate the significance. Results: A total of 6554 patients from 40 articles were included in this meta-analysis. It was shown in 37 studies with 4864 cases that the over-expression of XIAP was associated with poorer overall survival (OS) (combined HR=1.61, 95% CI: 1.33-1.96). Meanwhile, 8 studies with 1862 cases revealed that elevated XIAP level predicted shorter disease-free survival (DFS) (HR=2.17, 95% CI: 1.03-4.59). Subgroup analyses showed that higher XIAP detection was related to worse OS in gastric cancer (HR=1.42, 95% CI: 1.18-1.72) and head and neck cancer (HNC) (HR=2.97, 95% CI: 1.97-4.47). Conclusion: Our results suggested that elevated XIAP level seemed to represent an unfavorable prognostic factor for clinical outcomes in cancer patients. However, there were limited studies describing the association between XIAP expression and clinical prognosis in each different type of tumors. Therefore, concrete roles of XIAP in various cancers need to be further explored.

Epstein-Barr virus encoded microRNA BART7 regulates radiation sensitivity of nasopharyngeal carcinoma

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is very sensitive to radiotherapy. To date, the underlying mechanism remains poorly understood. Here, we demonstrated that expression of EBV-encoded microRNA BART7 (ebv-miR-BART7) increases responsiveness of NPC to radiation treatment by targeting GFPT1/TGFβ1 signaling. GFPT1 is the the key rate-limiting enzyme of the hexosamine signaling pathway and governs TGFβ1 production. TGFβ1, a pleotropic cytokine with the potency to trigger self-renewal and damage-repair machinery in somatic cells. TGFβ1 can protect zebrafish embryo from the lethal effects of radiation treatment. In silico analysis showed that ebv-miR-BART7 could target GFPT1 transcript. Correlation analysis on primary NPC tissues suggested that ebv-miR-BART7 and GFPT1 have negative expression correlation. Expression of GFPT1 and TGFβ1 were inducible by radiation in NPC cell with ebv-miR-BART7 expression. Further, suppressing endogenous GFPT1 expression inhibited TGFβ1 which subsequently increased the responsiveness of NPC to radiation treatment. Taken together, our results demonstrated that ebv-miR-BART7 controls TGFβ1 production by targeting GFPT1. Detection of ebv-miR-BART7 may provide useful indicator for monitoring NPC progression and predict therapeutic outcomes.

Pretreatment hematologic markers as prognostic factors in patients with nasopharyngeal carcinoma: A systematic review and meta-analysis

BACKGROUND

Pretreatment hematologic parameters of the inflammatory response, including lymphocyte, neutrophil, and platelet counts, neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio, and platelet-to-lymphocyte ratio, have emerged as prognostic factors for patients with cancer. This systematic review and meta-analysis aimed to summarize the association between the hematologic markers and prognosis of nasopharyngeal carcinoma (NPC).

METHODS

A systematic search of PubMed, Google Scholar, MEDLINE, EMBASE, Web of Science, and the Cochrane Library was conducted up to April 2016. Hazard ratios (HRs) with 95% confidence intervals (95% CIs) were extracted and synthesized to examine prognostic outcomes including cancer-specific survival (CSS), overall survival (OS), progression-free survival (PFS), distant metastasis-free survival, and local relapse-free survival (LRFS).

RESULTS

Fourteen studies comprising 11,651 NPC patients were ultimately included, and all eligible studies were conducted in East Asia. The OS, CSS, PFS, distant metastasis-free survival, and LRFS risks differed among patients according to hematologic marker levels. All of the parameters were associated with prognostic outcomes in patients with NPC. NLR and lymphocyte counts were most commonly reported. A high NLR was significantly associated with poor NPC prognosis (pooled HR 1.42, 95% CI 1.21-1.67 for CSS; pooled HR 1.77, 95% CI 1.41-2.23 for OS; pooled HR 1.67, 95% CI 1.36-2.06 for PFS; pooled HR 1.64, 95% CI 1.15-2.34 for LRFS). High lymphocyte count indicated favorable NPC prognosis (pooled HR 0.72, 95% CI 0.64-0.81 for OS; pooled HR 0.71, 95% CI 0.56-0.91 for PFS).

CONCLUSIONS

Meta-analysis indicated that NLR and lymphocyte counts could be prognostic predictors in NPC for East Asian population. Patients with a high NLR or low lymphocyte count had poor prognosis. However, due to the limitation of included population, the conclusion was limited to East Asian patients only.