ASB3 promotes hepatocellular carcinoma progression by mediating DR5 ubiquitination in TRAIL resistance

Ankyrin-repeat proteins with a suppressor of cytokine signaling box (ASB) proteins belong to the E3 ubiquitin ligase family. 18 ASB members have been identified whose biological functions are mostly unexplored. Here, we discovered that ASB3 was essential for hepatocellular carcinoma (HCC) development and high ASB3 expression predicted poor clinical outcomes. ASB3 silencing induced HCC cell growth arrest and apoptosis in vitro and in vivo. Liver-specific deletion of Asb3 gene suppressed diethylnitrosamine (DEN)-induced liver cancer development. Mechanistically, ASB3 interacted with death receptor 5 (DR5), which promoted ubiquitination and degradation of DR5. We further showed that ASB3 knockdown stabilized DR5 and increased the sensitivity of liver cancer cells to the treatment of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a DR5-dependent manner in cellular and in animal models. In summary, we demonstrated that ASB3 promoted ubiquitination and degradation of DR5 in HCC, suggesting the potential of targeting ASB3 to HCC treatment and overcome TRAIL resistance.

A novel report of Cys1298Gly mutation in exon 24 of NOTCH3 gene in a Chinese family with CADASIL

OBJECTIVES

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is the most common monogenic hereditary small cerebral vessel disease, which is caused by mutation of the neurogenic locus notch homolog protein 3 gene (NOTCH3). The exon 24 encodes EGF-like repeats, variants on this exon are rare. Here, we report a novel heterozygous variant c.3892 T >G (p. Cys1298Gly) on exon 24 of NOTCH3 gene in a 57-year-old Chinese woman.

MATERIALS AND METHODS

We present a patient with clinical manifestations, laboratory examination and imaging reveal suspicion of CADASIL. The family and genetic test and pathological examination were performed.

RESULTS

Magnetic resonance imaging revealed diffuse leukoencephalopathy with hyperintense signals in the bilateral temporal poles, periventricular white matter, centrum semiovale, basal ganglia, frontal and parietal cortex and subcortical areas bilaterally. Molecular Genetic testing identified a heterozygous variant c.3892 T >G (p. Cys1298Gly) on exon 24 of NOTCH3 gene. Her brother and his son were confirmed as subclinical carriers of the variant. The skin biopsy was negative, but the pathologic role of this mutation is predicted by using the DynaMut database and results showed the stability of the NOTCH gene is decreased.

CONCLUSIONS

To the best of our knowledge, this is the second case of exon 24 mutations reported from China and the variant of c.3892 T >G (p. Cys1298Gly) on exon 24 of NOTCH3 has not been reported so far. Our report broadens the mutation spectrum of the NOTCH3 gene in CADASIL.

Augmenting the therapeutic efficacy of adenosine against pancreatic cancer by switching the Akt/p21-dependent senescence to apoptosis

Background

There are many reports of the anti-tumour effects of exogenous adenosine in gastrointestinal tumours. Gemcitabine, a first line agent for patients with poor performance status, and adenosine have structural similarities. For these reasons, it is worth exploring the therapeutic efficacy of adenosine and its underlying mechanism in pancreatic cancer.

Methods

Tumour volumes and survival periods were measured in a patient-derived xenograft (PDX) model of pancreatic cancer. The Akt-p21 signalling axis was blocked by p21 silencing or by the Akt inhibitor GSK690693. The combined effect of GSK690693 and adenosine was calculated by the Chou-Talalay equation and verified by measuring fluorescent areas in orthotopic models.

Findings

Among the PDX mice, the tumour volume in the adenosine treatment group was only 61% of that in the saline treatment group. Adenosine treatment in combination with the Akt inhibitor, GSK690693, or the silencing of p21 to interfere with the Akt-p21 axis can switch the senescence-to-apoptosis signal and alleviate drug resistance. A GSK690693-adenosine combination caused 37.4% further reduction of tumour fluorescent areas in orthotopic models compared with that observed in adenosine monotherapy.

Interpretation: Our data confirmed the therapeutic effect of adenosine on pancreatic cancer, and revealed the potential of Akt inhibitors as sensitization agents in this treatment.

Fund

The work is supported by grants from the National Natural Science Foundation of China to Dongqin Yang (81572336, 81770579) and Jie Liu (81630016, 81830080), and jointly by the Development Fund for Shanghai Talents (201660).

The impact of TRAIL on proliferation of secretory prostate cancer PC-3 cell and LMO2 gene expression

OBJECTIVE

To determine the expressions of TRAIL protein and LMO2 gene in prostate cancer tissues with different differentiation degree and identify the influence of TRAIL on prostate cancer PC-3 cell proliferation.

PATIENTS AND METHODS

Surgical specimens from a total of 30 prostate cancer patients with radical prostatectomy were collected. The subjects were divided into three groups according to the different degrees of differentiation. TRAIL positive rate was detected by immunohistochemistry (IHC). LMO2 expression was assessed by Real-time PCR and Western-blot. PC-3 cell proliferation was determined by CCK-8 assay.

RESULTS

The positive rate of TRAIL protein was significantly higher in moderately differentiated group (80%) and well differentiated group (100%) compared with that in poorly differentiated group (54.55%), respectively (χ2 = 27.33, p < 0.05; χ2 = 40.12, p < 0.01). Streptavidin-peroxidase (SP) assay showed that TRAIL protein expression in well-differentiated group was significantly higher than that in moderately differentiated group and poorly differentiated group. qRT-PCR result demonstrated that LMO2 mRNA levels in moderately and well-differentiated group were significantly increased compared to that in poorly differentiated group (p < 0.001). Also, the proliferation rate of PC-3 cells in well-differentiated group was significantly higher than that in well-differentiated and moderately differentiated groups (p < 0.05).

CONCLUSION

Our data indicated that the positive rate of TRAIL protein increased in a prostate cancer differentiation dependent manner.

Targeting of the C-Jun/BCL-XL/P21 Axis Accelerates the Switch from Senescence to Apoptosis Upon ROC1 Knockdown in Gastric Cancer Cells

BACKGROUND/AIMS

Regulator of cullins-1 (ROC1) is a pivotal component of cullin-RING E3 ubiquitin ligases, which help to regulate distinct cellular processes by governing the degradation of various substrates. Because the role of ROC1 in gastric cancer is largely uncharacterized, we investigated the relationship between ROC1 expression and the prognosis of gastric cancer patients and explored the biological function of ROC1 and its underlying mechanisms in gastric cancer.

METHODS

Kaplan-Meier and multivariate Cox regression analyses were used to evaluate the correlation between the carcinogenesis of gastric cancer and ROC1. SA-β-gal staining and the senescence-associated secretory phenotype (SASP) were used to assess ROC1 silencing-induced cellular senescence. A xenograft zebrafish model was used to evaluate the effects of BCL-XL and ROC1 co-silencing on tumor formation in vivo.

RESULTS

High ROC1 expression was correlated with poor prognosis and a low 5-year survival rate of gastric cancer patients. ROC1 depletion significantly inhibited the growth of gastric cancer cells by sequentially inducing p21-mediated cellular senescence and mitochondrial-dependent apoptosis. Functional studies revealed successive upregulation of c-Jun, BCL-XL, and p21 upon ROC1 knockdown. BCL-XL suppression via RNA interference or a BH3 mimetic (ABT-737 or ABT-263) efficiently enhanced the anti-tumor effects of ROC1 knockdown. Equally as important, BCL-XL silencing strengthened ROC1 knockdown-induced apoptosis by blocking p21-mediated senescence.

CONCLUSIONS

The c-Jun/BCL-XL/p21 axis promotes senescence to resist ROC1 knockdown-induced apoptosis in gastric cancer cells. Targeted inactivation of BCL-XL could sensitize gastric cancer cells to ROC1 knockdown in clinical practice.

Suppression of AURKA alleviates p27 inhibition on Bax cleavage and induces more intensive apoptosis in gastric cancer

Bax is a key molecule in mitochondria-apoptosis pathway, however it is not always an efficient apoptosis inducer in chemotherapeutic agents-treated cancer cells. Here, we found that specific inhibition of AURKA by MLN8237-induced calpain-mediated Bax cleavage at N-terminal 33th asparagine (c-Bax) to promote apoptosis. The c-Bax, as Bax, could also efficiently located to mitochondria but c-Bax is a stronger apoptosis inducer than Bax. Morever, c-Bax-induced apoptosis could not be blocked by the canonical Bax inhibitor, Bcl-2. Further study found p27 was degraded and subsequently Bax was transformed to c-Bax through calpain. Also, p27 efficiently inhibited Bax cleavage and p27 knockdown sensitized apoptosis through Bax cleavage when cancer cells were treated with MLN8237. It is also demonstrated that the anti-apoptotic role of p27 lies its cytoplasmic localization. Finally, we found that the positive correlation between AURKA and p27 in advanced gastric cancer patients. In conclusion, we found that MNL8237 suppressed cell growth by regulating calpain-dependent Bax cleavage and p27 dysregulation in gastric cancer cells.

Targeting CAND1 promotes caspase-8/RIP1-dependent apoptosis in liver cancer cells

Cullin-associated NEDD8-dissociated 1 (CAND1) plays a vital role in regulating the activity of Cullin-RING ubiquitin ligases (CRLs), which are frequently dysregulated in cancer. However, the role of CAND1 in hepatocellular carcinoma (HCC) remains unknown. Here, we found that CAND1 was overexpressed in HCC tissues compared to corresponding adjacent liver tissues (71.7% vs 16.7%); high expression of CAND1 was associated with poor overall survival (40.7 vs 57.3 months, P=0.0013); and CAND1 was an independent risk factor for the prognosis of HCC patients (N=138, P=0.018). Functional studies revealed that CAND1 knockdown efficiently suppressed the proliferation of liver cancer cells by activating caspase-8-dependent mitochondrial apoptosis. We also observed a mutual activation loop between caspase-8 and Receptor Interacting Protein 1 (RIP1), which amplified CAND1 knockdown-induced apoptotic signals in the cells. Furthermore, RIP1 inhibitor Necrostatin-1 eliminated the activation of caspase-8. In conclusion, our study pioneered in reporting high CAND1 expression as a predictor of poor prognosis for HCC patients. CAND1 silencing suppressed HCC cell proliferation by inducing caspase-8/RIP1-dependent apoptosis. These findings supported that CAND1 could be a new therapeutic target for liver cancer.

Targeting high Aurora kinases expression as an innovative therapy for hepatocellular carcinoma

The Aurora kinases A and B control tumorigenesis by inhibiting apoptosis and promoting proliferation and metastasis, however, it remains unknown whether Aurora A and B overexpressed concomitantly and its clinical significance in hepatocellular carcinoma (HCC). Here, we obsearved Aurora A and B tended to overexpress parallelly on protein level (r = 0.8679, P < 0.0001) and their co-overexpression (Aurora A^HB^H), associated with the worst prognosis, was an independent predictor for the survival. Importantly, with the lower IC50 and stronger anti-tumor effect than selective inhibitors, SNS-314, the pan-inhibitor of Aurora kinases, which induced YAP (Yes-associated protein) reduction and resulted in P21 accumulation, significantly promoted the polyploidy (> 4N) formation and apoptosis in HCC. High YAP expression (YAP^H) was associated with Aurora A^HB^H, and appeared to be an independent predictor for survival, but P21 not. Moreover, silencing YAP also induced P21 accumulation, and knockdown P21, which enhanced YAP accumulation and weakened the SNS-314-induced YAP reduction, impaired SNS-314-induced apoptosis. Therefore, P21 enhanced the apoptotic effect of SNS-314 in HCC. Taken together, our findings indicated Aurora kinases/YAP/P21 was an oncogenic signaling axis in HCC, and revealed targeting Aurora A^HB^H induced apoptosis by YAP suppression. Our results also provided a solid evidence for SNS-314 as a potential targeted therapy, and a proof-of-concept evidence for a possible combined therapy of SNS-314 plus Hippo pathway inhibitors on HCC.

Diversity of killer cell immunoglobulin-like receptor genes in Drung Chinese

Killer cell immunoglobulin-like receptor (KIR) genes are variably distributed among populations from distinct geographic areas and ethnic origins. We describe, for the first time, KIR gene diversity in 152 unrelated and healthy Drung individuals, as measured by sequence-specific polymerase chain reaction. All 16 known KIR genes were detected. Of these, the framework genes KIR2DL4, 3DL2, 3DL3, and 3DP1 were present in all individuals as expected, along with the non-framework genes KIR2DL1, 2DL3, and 2DP1. In contrast, KIR2DL2, 2DS2, and 2DS5 were unusually rare, suggesting that KIR gene distribution was relatively concentrated. Ten different KIR genotypes were found, of which the most common consisted of nine genes (KIR2DL1, 2DL3, 2DL4, 2DS4, 3DL1, 3DL2, 3DL3, 2DP1, and 3DP1) and accounted for 66.4% of participants. There were eight different haplotypes present, of which the A haplotype was the most common (81.9%). Principal components and dendrogram analysis confirmed that the Drung Chinese are most closely related to the Japanese, the Zhejiang Han, and the Yunnan Han. In conclusion, distinctive frequencies of KIR genes, haplotypes, and genotypes are observed in Chinese Drung.

Antibody-mediated neutralization of human rhinovirus 14 explored by means of cryoelectron microscopy and X-ray crystallography of virus-Fab complexes

The structures of three different human rhinovirus 14 (HRV14)-Fab complexes have been explored with X-ray crystallography and cryoelectron microscopy procedures. All three antibodies bind to the NIm-IA site of HRV14, which is the beta-B-beta-C loop of the viral capsid protein VP1. Two antibodies, Fab17-IA (Fab17) and Fab12-IA (Fab12), bind bivalently to the virion surface and strongly neutralize viral infectivity whereas Fab1-IA (Fab1) strongly aggregates and weakly neutralizes virions. The structures of the two classes of virion-Fab complexes clearly differ and correlate with observed binding neutralization differences. Fab17 and Fab12 bind in essentially identical, tangential orientations to the viral surface, which favors bidentate binding over icosahedral twofold axes. Fab1 binds in a more radial orientation that makes bidentate binding unlikely. Although the binding orientations of these two antibody groups differ, nearly identical charge interactions occur at all paratope-epitope interfaces. Nucleotide sequence comparisons suggest that Fab17 and Fab12 are from the same progenitor cell and that some of the differing residues contact the south wall of the receptor binding canyon that encircles each of the icosahedral fivefold vertices. All of the antibodies contact a significant proportion of the canyon region and directly overlap much of the receptor (intercellular adhesion molecule 1 [ICAM-1]) binding site. Fab1, however, does not contact the same residues on the upper south wall (the side facing away from fivefold axes) at the receptor binding region as do Fab12 and Fab17. All three antibodies cause some stabilization of HRV14 against pH-induced inactivation; thus, stabilization may be mediated by invariant contacts with the canyon.

[Study on the immune state of patients with laryngeal carcinoma]

The authors have carried out the immunoassay on 68 patients with laryngeal carcinoma in order to investigate the relationship between the occurrence and development of the tumour and the body immune state by using the methods of R1D, APAAP and LDH. The results showed that, in comparison with the normal group, CD3+, CD4+ cell and NK cell activity were much lower (P < 0.01), CD8+ cell slightly increased (P > 0.05). IgG, IgA and IgM were also lower (P < 0.05). It indicates that the lower level of cellular immunity, the descent of the ratio of CD4+/CD8+ and the condition which suppresses the body immune system are the interior factors which make the laryngeal carcinoma happening and developing easily. With the development of tumor, the increase of various suppressor factors and the immune system suppressed further the tumor can spread and shift much more easily.

The characterization and crystallization of a virally encoded Ustilago maydis KP4 toxin

KP4 is a virally encoded and highly specific toxin that kills fungi closely related to the fungus Ustilago maydis. The toxin was purified and crystals were formed using ammonium sulfate as precipitant. The crystals belong to the space group P6(1)(5)22 and diffracted to approximately 2.2 A resolution. Circular dicroism spectroscopy suggests that the protein is predominantly comprised of beta-strands.