Knockdown of XAB2 Enhances All-Trans Retinoic Acid–Induced Cellular Differentiation in All-Trans Retinoic Acid–Sensitive and –Resistant Cancer Cells

DNA Repair Protein HELQ and XAB2 as Chemoresponse and Prognosis Biomarkers in Ascites Tumor Cells of High-Grade Serous Ovarian Cancer

Nucleotide excision repair (NER) is an important mediator for responsiveness of platinum-based chemotherapy. Our study is aimed at investigating the NER-related genes expression in ascites tumor cells and its application in the prediction of chemoresponse in high-grade serous ovarian cancer (HGSC) patients. The relationship between 16 NER-related genes and the prognosis of ovarian cancer was analyzed in the TCGA database. NER-related genes including HELQ and XAB2 expressions were determined via immunocytochemistry in ascites cell samples from 92 ovarian cancer patients prior to primary cytoreduction surgery. Kaplan-Meier analysis and Cox model were used to investigate the association between NER-related gene expression and prognosis/chemotherapeutic response. Predicting models were constructed using a training cohort of 60 patients and validated in a validation cohort of 32 patients. We found that high expression of HELQ and XAB2 in the training cohort was associated with poor prognosis (for HELQ, P = 0.001, HR = 2.83, 95% CI: 1.46-5.49; for XAB2, P = 0.008, HR = 2.38, 95% CI: 1.23-4.63) and platinum resistance (for HELQ, P < 0.001; for XAB2, P = 0.006). In the validation cohort, the combination of HELQ and XAB2 (AUC = 0.863) showed the highest AUC. The expression levels of HELQ (RR 5.7, 95% CI 1.7-19.2) and XAB2 (RR 3.2, 95% CI 0.9-10.8) in ascites tumor cells were positively correlated to the risk of platinum resistance. In summary, we revealed that the expression levels of HELQ and XAB2 are candidate predictors for primary chemotherapy responsiveness and prognosis in HGSC. Ascites cytology is applicable as a promising method for chemosensitivity prediction in HGSC.

XAB2 TagSNP Is Associated with the Risk of Gastric Cancer in Chinese Population: A Case-Control Study

XAB2 protein (xeroderma pigmentosum group A-binding protein 2) plays a significant role in the nucleotide excision repair pathway. Polymorphisms in the XAB2 gene may have an effect on the capability of DNA repair and further contribute to the risk of developing various cancers. In order to investigate the relationship between XAB2 genetic variants and the risk of gastric cancer, we performed a hospital-based case–control study. XAB2 tagSNPs were selected and then genotyped by iPlex Gold Genotyping Assay and Sequenom MassArray. By performing logistic regression analysis, odds ratio (OR) and 95% confidence interval (CI) were used to estimate the association of XAB2 tagSNPs with the risk of gastric cancer. Our results showed that XAB2 rs794078AA genotype was associated with a significantly lower risk of gastric cancer compared with GG genotype with OR (95% CI) of 0.33 (0.12–0.91). Stratified analysis indicated a significantly decreased risk for gastric cancer among smokers with rs794078AA genotype compared with nonsmokers with GG genotype (OR = 0.11, 95% CI = 0.01–0.91, p = 0.040). The gene–gene interactions by multifactor dimensionality reduction (MDR) showed that tagSNP rs794078 was the best predictive element for gastric cancers (Testing Bal. Acc = 51.68%, p = 0.055, cross-validation consistency = 9). Therefore, the XAB2 tagSNP rs794078 may play an important role in the development of gastric cancer.

Current Trends in ATRA Delivery for Cancer Therapy

All-Trans Retinoic Acid (ATRA) is the most active metabolite of vitamin A. It is critically involved in the regulation of multiple processes, such as cell differentiation and apoptosis, by activating specific genomic pathways or by influencing key signaling proteins. Furthermore, mounting evidence highlights the anti-tumor activity of this compound. Notably, oral administration of ATRA is the first choice treatment in Acute Promyelocytic Leukemia (APL) in adults and NeuroBlastoma (NB) in children. Regrettably, the promising results obtained for these diseases have not been translated yet into the clinics for solid tumors. This is mainly due to ATRA-resistance developed by cancer cells and to ineffective delivery and targeting. This up-to-date review deals with recent studies on different ATRA-loaded Drug Delivery Systems (DDSs) development and application on several tumor models. Moreover, patents, pre-clinical, and clinical studies are also reviewed. To sum up, the main aim of this in-depth review is to provide a detailed overview of the several attempts which have been made in the recent years to ameliorate ATRA delivery and targeting in cancer.

Targeting CD26 suppresses proliferation of malignant mesothelioma cell via downmodulation of ubiquitin-specific protease 22

Malignant pleural mesothelioma (MPM) is an aggressive malignancy arising from mesothelial lining of pleura. It is associated with a poor prognosis, partly due to the lack of a precise understanding of the molecular mechanisms associated with its malignant behavior. In the present study, we expanded on our previous studies on cell cycle control of MPM cells by targeting CD26 molecule with humanized anti-CD26 monoclonal antibody (HuCD26mAb), focusing particularly on ubiquitin-specific protease 22 (USP22). We showed that USP22 protein expression is detected in clinical specimens of MPM and that USP22 knockdown, as well as CD26 knockdown, significantly inhibits the growth and proliferation of MPM cells in vitro and in vivo. Moreover, depletion of both USP22 and CD26 suppresses MPM cell proliferation even more profoundly. Furthermore, expression levels of USP22 correlate with those of CD26. HuCD26mAb treatment induces a decrease in USP22 level through its interaction with the CD26 molecule, leading to increased levels of ubiquitinated histone H2A and p21. By demonstrating a CD26-related linkage with USP22 in MPM cell inhibition induced by HuCD26mAb, our present study hence characterizes USP22 as a novel target molecule while concurrently suggesting a new therapeutic strategy for MPM.

Heroin Abuse Results in Shifted RNA Expression to Neurodegenerative Diseases and Attenuation of TNFα Signaling Pathway

Repeated administration of heroin results in the induction of physical dependence, which is characterized as a behavioral state of compulsive drug seeking and a high rate of relapse even after periods of abstinence. However, few studies have been dedicated to characterization of the long-term alterations in heroin-dependent patients (HDPs). Herein, we examined the peripheral blood from 810 HDPs versus 500 healthy controls (HCs) according to the inclusion criteria. Compared with the control group, significant decreases of albumin, triglyceride, and total cholesterol levels were identified in HDPs (P < 0.001) versus HCs coupled with an insignificant decrease in BMI. Meanwhile, RNA-sequencing analyses were performed on blood of 16 long-term HDPs and 25 HCs. The results showed that the TNFα signaling pathway and hematopoiesis related genes were inhibited in HDPs. We further compared the transcriptome data to those of SCA2 and posttraumatic stress disorder patients, identified neurodegenerative diseases related genes were commonly up-regulated in coupled with biological processes "vesicle transport", "mitochondria" and "splicing". Genes in the categories of "protein ubiquitination" were down-regulated indicating potential biochemical alterations shared by all three comparative to their controls. In summary, this is a leading study performing a series of through investigations and using delicate approaches. Results from this study would benefit the study of drug addiction overall and link long-term heroin abuse to neurodegenerative diseases.

Why Differentiation Therapy Sometimes Fails: Molecular Mechanisms of Resistance to Retinoids

Retinoids represent a popular group of differentiation inducers that are successfully used in oncology for treatment of acute promyelocytic leukemia in adults and of neuroblastoma in children. The therapeutic potential of retinoids is based on their key role in the regulation of cell differentiation, growth, and apoptosis, which provides a basis for their use both in cancer therapy and chemoprevention. Nevertheless, patients treated with retinoids often exhibit or develop resistance to this therapy. Although resistance to retinoids is commonly categorized as either acquired or intrinsic, resistance as a single phenotypic feature is usually based on the same mechanisms that are closely related or combined in both of these types. In this review, we summarize the most common changes in retinoid metabolism and action that may affect the sensitivity of a tumor cell to treatment with retinoids. The availability of retinoids can be regulated by alterations in retinol metabolism or in retinoid intracellular transport, by degradation of retinoids or by their efflux from the cell. Retinoid effects on gene expression can be regulated via retinoid receptors or via other molecules in the transcriptional complex. Finally, the role of small-molecular-weight inhibitors of altered cell signaling pathways in overcoming the resistance to retinoids is also suggested.

XAB2 functions in mitotic cell cycle progression via transcriptional regulation of CENPE

Xeroderma pigmentosum group A (XPA)-binding protein 2 (XAB2) is a multi-functional protein that plays critical role in processes including transcription, transcription-coupled DNA repair, pre-mRNA splicing, homologous recombination and mRNA export. Microarray analysis on gene expression in XAB2 knockdown cells reveals that many genes with significant change in expression function in mitotic cell cycle regulation. Fluorescence-activated cell scanner analysis confirmed XAB2 depletion led to cell arrest in G2/M phase, mostly at prophase or prometaphase. Live cell imaging further disclosed that XAB2 knockdown induced severe mitotic defects including chromosome misalignment and defects in segregation, leading to mitotic arrest, mitotic catastrophe and subsequent cell death. Among top genes down-regulated by XAB2 depletion is mitotic motor protein centrosome-associated protein E (CENPE). Knockdown CENPE showed similar phenotypes to loss of XAB2, but CENPE knockdown followed by XAB2 depletion did not further enhance cell cycle arrest. Luciferase assay on CENPE promoter showed that overexpression of XAB2 increased luciferase activity, whereas XAB2 depletion resulted in striking reduction of luciferase activity. Further mapping revealed a region in CENPE promoter that is required for the transcriptional regulation by XAB2. Moreover, ChIP assay showed that XAB2 interacted with CENPE promoter. Together, these results support a novel function of XAB2 in mitotic cell cycle regulation, which is partially mediated by transcription regulation on CENPE.

XAB2 tagSNPs contribute to non-small cell lung cancer susceptibility in Chinese population

Background

XPA-binding protein 2 (XAB2) interacts with Cockayne syndrome complementation group A (CSA), group B (CSB) and RNA polymerase II to initiate nucleotide excision repair. This study aims to evaluate the association of XAB2 genetic variants with the risk of non-small cell lung cancer (NSCLC) using a tagging approach.

Methods

A hospital-based case-control study was conducted in 470 patients with NSCLC and 470 controls in Chinese population. Totally, 5 tag single nucleotide polymorphisms (SNPs) in XAB2 gene were selected by Haploview software using Hapmap database. Genotyping was performed using iPlex Gold Genotyping Asssy and Sequenom MassArray. Unconditional logistic regression was conducted to estimate odd ratios (ORs) and 95 % confidence intervals (95 % CI).

Results

Unconditional logistic regression analysis showed that the XAB2 genotype with rs794078 AA or at least one rs4134816 C allele were associated with the decreased risk of NSCLC with OR (95 % CI) of 0.12 (0.03–0.54) and 0.46 (0.26–0.84). When stratified by gender, we found that the subjects carrying rs4134816 CC or CT genotype had a decreased risk for developing NSCLC among males with OR (95 % CI) of 0.39 (0.18–0.82), but not among females. In age stratification analysis, we found that younger subjects (age ≤ 60) with at least one C allele had a decreased risk of NSCLC with OR (95 % CI) of 0.35 (0.17–0.74), but older subjects didn’t. We didn’t find that XAB2 4134816 C > T variant effect on the risk of NSCLC when stratified by smoking status. The environmental factors, such as age, sex and smoking had no effect on the risk of NSCLC related to XAB2 genotypes at other polymorphic sites.

Conclusions

The XAB2 tagSNPs (rs794078 and rs4134816) were significantly associated with the risk of NSCLC in Chinese population, which supports the XAB2 plays a significant role in the development of NSCLC.

Hematopoietic myeloid cell differentiation diminishes nucleotide excision repair

Myeloid cell differentiation is the process by which stem cells develop into mature monocytes or granulocytes. This process is achieved by the sequential activation of variety of genes. Disruption of this process can result in immunodeficiency, bone marrow failure syndrome, or leukemia. Acute promyelocytic leukemia (APL) is characterized by the t(15;17) translocation and can be treated by a combination of all-trans retinoic acid (ATRA) and anthracycline. This treatment can induce leukemic cell differentiation, leading to extremely high remission rates. XAB2, a molecule involved in nucleotide excision repair (NER), is downregulated during granulocyte differentiation and shows reduced expression in NB4 APL-derived cells in vitro. Differentiation of APL by ATRA treatment reduced XAB2 expression levels in vivo. These observations suggest that cellular differentiation is associated with reduced NER activity and provides new insights into combined differentiation induction. NB4 cells were more susceptible than the immature myeloid leukemic cell lines, Kasumi-3 and Kasumi-1, to the DNA interstrand crosslinking agent cisplatin.

CD26-mediated regulation of periostin expression contributes to migration and invasion of malignant pleural mesothelioma cells

Malignant pleural mesothelioma (MPM) is an aggressive malignancy arising from mesothelial lining of pleura. It is generally associated with a history of asbestos exposure and has a very poor prognosis, partly due to the lack of a precise understanding of the molecular mechanisms associated with its malignant behavior. In the present study, we expanded on our previous studies on the enhanced motility and increased CD26 expression in MPM cells, with a particular focus on integrin adhesion molecules. We found that expression of CD26 upregulates periostin secretion by MPM cells, leading to enhanced MPM cell migratory and invasive activity. Moreover, we showed that upregulation of periostin expression results from the nuclear translocation of the basic helix-loop-helix transcription factor Twist1, a process that is mediated by CD26-associated activation of Src phosphorylation. While providing new and profound insights into the molecular mechanisms involved in MPM biology, these findings may also lead to the development of novel therapeutic strategies for MPM.

Neuroblastoma in a 55-year-old patient: a case report

Background

Neuroblastomas account for 97% of all neuroblastic tumors and for approximately 15% of all pediatric cancer fatalities. However, in adults neuroblastoma is a very rare finding.

Case Report

Here, we present the case of a 55-year-old patient who was diagnosed with neuroblastoma stage IV one year after the false diagnosis of a non-secretory multiple myeloma.

Results

The patient received six cycles of a chemotherapy protocol with cisplatin, etoposide and vindesine alternating with vincristine, dacarbazine, ifosfamide and doxorubicin, but the response to treatment was insufficient (stable disease).

Conclusion

The standard chemotherapy protocols used for children are not sufficient for adult patients. Different treatment approaches are needed to improve the prognosis of adult patients with neuroblastoma.

New approaches to pharmacotherapy of tumors of the nervous system during childhood and adolescence

Tumors of the nervous system are among the most common and most chemoresistant neoplasms of childhood and adolescence. Malignant tumors of the brain collectively account for 21% of all cancers and 24% of all cancer-related deaths in this age group. Neuroblastoma, a peripheral nervous system tumor, is the most common extracranial solid tumor of childhood, and 65% of children with this tumor have only a 10 or 15% chance of living 5 years beyond the time of initial diagnosis. Novel pharmacological approaches to nervous system tumors are urgently needed. This review presents the role of and current challenges to pharmacotherapy of malignant tumors of the nervous system during childhood and adolescence and discusses novel approaches aimed at overcoming these challenges.

Gene expression profiles in human lymphocytes irradiated in vitro with low doses of gamma rays

The molecular mechanisms underlying responses to low radiation doses are still unknown, especially in normal lymphocytes, despite the evidence suggesting specific changes that may characterize cellular responses. Our purpose was to analyze gene expression profiles by DNA microarrays in human lymphocytes after in vitro irradiation (10, 25 and 50 cGy) with gamma rays. A cytogenetic analysis was also carried out for different radiation doses. G 0 lymphocytes were irradiated and induced to proliferate for 48 h; then RNA samples were collected for gene expression analysis. ANOVA was applied to data obtained in four experiments with four healthy donors, followed by SAM analysis and hierarchical clustering. For 10, 25 and 50 cGy, the numbers of significantly (FDR <or= 0.05) modulated genes were 86, 130 and 142, respectively, and 25, 35 and 33 genes were exclusively modulated for each dose, respectively. We found CYP4X1, MAPK10 and ATF6 (10 cGy), DUSP16 and RAD51L1 (25 cGy), and RAD50, REV3L and DCLRE1A (50 cGy). A set of 34 significant genes was common for all doses; while SERPINB2 and C14orf104 were up-regulated, CREB3L2, DDX49, STK25 and XAB2 were down-regulated. Chromosome damage was significantly induced for doses >or=10 cGy (total aberrations) and >or=50 cGy (dicentrics/ rings). Therefore, low to moderate radiation doses induced qualitative and/or quantitative differences and similarities in transcript profiles, reflecting the type and extent of DNA lesions. The main biological processes associated with modulated genes were metabolism, stress response/DNA repair, cell growth/differentiation, and transcription regulation. The results indicate a potential risk to humans regarding the development of genetic instability and acquired diseases.

Isolation of XAB2 complex involved in pre-mRNA splicing, transcription, and transcription-coupled repair

Nucleotide excision repair is a versatile repair pathway that counteracts the deleterious effects of various DNA lesions. In nucleotide excision repair, there is a transcription-coupled repair (TCR) pathway that focuses on DNA damage that blocks RNA polymerase IIo in transcription elongation. XAB2 (XPA-binding protein 2), containing tetratricopeptide repeats, has been isolated by virtue of its ability to interact with xeroderma pigmentosum group A protein (XPA). Moreover, XAB2 has been shown to interact with Cockayne syndrome group A and B proteins (CSA and CSB) and RNA polymerase II, as well as XPA, and is involved in TCR and transcription. Here we purified XAB2 as a multimeric protein complex consisting of hAquarius, XAB2, hPRP19, CCDC16, hISY1, and PPIE, which are involved in pre-mRNA splicing. Knockdown of XAB2 with small interfering RNA in HeLa cells resulted in a hypersensitivity to killing by UV light and a decreased recovery of RNA synthesis after UV irradiation and regular RNA synthesis. Enhanced interaction of XAB2 with RNA polymerase IIo or XPA was observed in cells treated with DNA-damaging agents, indicating DNA damage-responsive activity of the XAB2 complex. These results indicated that the XAB2 complex is a multifunctional factor involved in pre-mRNA splicing, transcription, and TCR.

Diverse actions of retinoid receptors in cancer prevention and treatment

Retinoids (retinol [vitamin A] and its biologically active metabolites) are essential signaling molecules that control various developmental pathways and influence the proliferation and differentiation of a variety of cell types. The physiological actions of retinoids are mediated primarily by the retinoic acid receptors alpha, beta, and gamma (RARs) and rexinoid receptors alpha, beta, and gamma. Although mutations in RARalpha, via the PML-RARalpha fusion proteins, result in acute promyelocytic leukemia, RARs have generally not been reported to be mutated or part of fusion proteins in carcinomas. However, the retinoid signaling pathway is often compromised in carcinomas. Altered retinol metabolism, including low levels of lecithin:retinol acyl trasferase and retinaldehyde dehydrogenase 2, and higher levels of CYP26A1, has been observed in various tumors. RARbeta(2) expression is also reduced or is absent in many types of cancer. A greater understanding of the molecular mechanisms by which retinoids induce cell differentiation, and in particular stem cell differentiation, is required in order to solve the issue of retinoid resistance in tumors, and thereby to utilize RA and synthetic retinoids more effectively in combination therapies for human cancer.

Apoptosis related protein 3, an ATRA-upregulated membrane protein arrests the cell cycle at G1/S phase by decreasing the expression of cyclin D1

Human Apr3 was first cloned from HL-60 cells treated by ATRA. In this study, we further demonstrated that Apr3 could be obviously upregulated by ATRA in many other ATRA sensitive cells, suggesting a common role of Apr3 in ATRA effects. Indirect immunofluorescence assay indicates that Apr3 is a membrane protein, while its truncated form without the predicted transmembrane and intracellular domain, was likely a secreted one. Furthermore, FACS analysis showed that Apr3 overexpression could cause an obvious G1/S phase arrest which might be induced by dramatic reduction of cyclin D1 expression. Strikingly, the truncated Apr3 antagonized the negative role of Apr3 on cell cycle and cyclin D1. Taken together, our data suggest that Apr3 should play an important role in ATRA signal pathway and the predicted transmembrane and/or the intracellular domain mediates Apr3 membrane localization and is vital for the negative regulation on cell cycle and cyclin D1.