alpha-, beta-, and gamma-Tubulin polymerization in response to DNA damage

RNA-Sequencing Analysis of Gene-Expression Profiles in the Dorsal Gland of Alligator sinensis at Different Time Points of Embryonic and Neonatal Development

Significant advances have been made in the morphological observations of the dorsal gland (DG), an oval organ/tissue which lies on both sides of the dorsal midline of the crocodilian. In the current study, RNA sequencing (RNA-seq) was used to identify the changing patterns of Alligator sinesis DGs at different timepoints from the 31st embryonic day (E31) to the newly hatched 1st day (NH1). A comprehensive transcriptional changes of differentially expression gene (DEGs) involved in the melanogenesis, cholesterol metabolism, and cell apoptosis pathways suggested that the DG might serves as a functional secretory gland in formation, transport and deposition of pigment, and lipids secretion via lysosomal exocytosis. Furthermore, the remarkable immunohistochemical staining of proliferating cell nuclear antigen (PCNA) and B-cell lymphoma 2 (Bcl-2)-positive signals in the basilar cells, in parallel with the immuno-reactive TdT-mediated dUTP nick-End labeling(TUNEL) within suprabasal cells, provided direct molecular evidence supporting for the speculation that DG serves as a holocrine secretion mode. Finally, subsequent phylogenetic and immunohistochemical analysis for the PITX2, the identified DEGs in the RNA-seq, was helpful to further elucidate the transcriptional regulatory mechanism of candidate genes. In conclusion, the current results are of considerable importance in enriching our understanding of the intrinsic relationship between the skin derivatives and lifestyles of newborn Alligator sinesis.

Kinesin Kif2C in regulation of DNA double strand break dynamics and repair

DNA double strand breaks (DSBs) have detrimental effects on cell survival and genomic stability, and are related to cancer and other human diseases. In this study, we identified microtubule-depolymerizing kinesin Kif2C as a protein associated with DSB-mimicking DNA templates and known DSB repair proteins in Xenopus egg extracts and mammalian cells. The recruitment of Kif2C to DNA damage sites was dependent on both PARP and ATM activities. Kif2C knockdown or knockout led to accumulation of endogenous DNA damage, DNA damage hypersensitivity, and reduced DSB repair via both NHEJ and HR. Interestingly, Kif2C depletion, or inhibition of its microtubule depolymerase activity, reduced the mobility of DSBs, impaired the formation of DNA damage foci, and decreased the occurrence of foci fusion and resolution. Taken together, our study established Kif2C as a new player of the DNA damage response, and presented a new mechanism that governs DSB dynamics and repair.

Expression of ERCC1, RRM1, TUBB3 in correlation with apoptosis repressor ARC, DNA mismatch repair proteins and p53 in liver metastasis of colorectal cancer

Liver metastasis in colorectal cancer is common and the primary treatment is chemotherapy. To date, there is no routinely used test in clinical practice to predict the effectiveness of conventional chemotherapy. Therefore, biomarkers with predictive value for conventional chemotherapy would be of considerable benefit in treatment planning. We analysed three proteins [excision repair cross-complementing 1 (ERCC1), ribonucleoside-diphosphate reductase 1 (RRM1) and class III β-tubulin (TUBB3)] in colorectal cancer liver metastasis. We used tissue microarray slides with 101 liver metastasis samples, stained for ERCC1, RRM1 and TUBB3 and established scoring systems (fitted for tissue microarray) for each protein. In statistical analysis, we compared the expression of ERCC1, RRM1 and TUBB3 to mismatch proteins (MLH1, MSH2, MSH6 and PMS2), p53 and to apoptosis repressor protein (ARC). Statistically significant correlations were found between ERCC1, TUBB3 and MLH1, MSH2 and RRM1 and MSH2, MSH6. Noteworthy, our analysis revealed a strong significant correlation between cytoplasmic ARC expression and RRM1, TUBB3 (p=0.000 and p=0.001, respectively), implying an additional role of TUBB3 and RRM1 not only in therapy resistance, but also in the apoptotic machinery. Our data strengthens the importance of ERCC1, TUBB3 and RRM1 in the prediction of chemotherapy effectiveness and suggest new functional connections in DNA repair, microtubule network and apoptotic signaling (i.e. ARC protein). In conclusion, we showed the importance and need of predictive biomarkers in metastasized colorectal cancer and pointed out the relevance not only of single predictive markers but also of their interactions with other known and newly explored relations between different signaling pathways.

Root proteomics reveals cucumber 24-epibrassinolide responses under Ca(NO3)2 stress

The application of exogenous 24-epibrassinolide promotes Brassinosteroids intracellular signalling in cucumber, which leads to differentially expressed proteins that participate in different life process to relieve Ca(NO 3 ) 2 damage. NO3 (-) and Ca(2+) are the main anion and cation of soil secondary salinization during greenhouse cultivation. Brassinosteroids (BRs), steroidal phytohormones, regulate various important physiological and developmental processes and are used against abiotic stress. A two-dimensional electrophoresis gel coupled with MALDI-TOF/TOF MS was performed to investigate the effects of exogenous 24-epibrassinolide (EBL) on proteomic changes in cucumber seedling roots under Ca(NO3)2 stress. A total of 80 differentially accumulated protein spots in response to stress and/or exogenous EBL were identified and grouped into different categories of biological processes according to Gene Ontology. Under Ca(NO3)2 stress, proteins related to nitrogen metabolism and lignin biosynthesis were induced, while those related to cytoskeleton organization and cell-wall neutral sugar metabolism were inhibited. However, the accumulation of abundant proteins involved in protein modification and degradation, defence mechanisms against antioxidation and detoxification and lignin biosynthesis by exogenous EBL might play important roles in salt tolerance. Real-time quantitative PCR was performed to investigate BR signalling. BR signalling was induced intracellularly under Ca(NO3)2 stress. Exogenous EBL can alleviate the root indices, effectively reduce the Ca(2+) content and increase the K(+) content in cucumber roots under Ca(NO3)2 stress. This study revealed the differentially expressed proteins and BR signalling-associated mRNAs induced by EBL in cucumber seedling roots under Ca(NO3)2 stress, providing a better understanding of EBL-induced salt resistance in cucumber seedlings. The mechanism for alleviation provides valuable insight into improving Ca(NO3)2 stress tolerance of other horticultural plants.

High TUBB3 expression, an independent prognostic marker in patients with early non-small cell lung cancer treated by preoperative chemotherapy, is regulated by K-Ras signaling pathway

We assessed the prognostic and predictive value of β-tubulin III (TUBB3) expression, as determined by immunohistochemistry, in 412 non-small cell lung cancer (NSCLC) specimens from early-stage patients who received neoadjuvant chemotherapy (paclitaxel- or gemcitabine-based) in a phase III trial (IFCT-0002). We also correlated TUBB3 expression with K-Ras and EGF receptor (EGFR) mutations in a subset of 208 cryopreserved specimens. High TUBB3 protein expression was associated with nonsquamous cell carcinomas (P < 0.001) and K-Ras mutation (P < 0.001). The 127 (30.8%) TUBB3-negative patients derived more than 1 year of overall survival advantage, with more than 84 months median overall survival versus 71.7 months for TUBB3-positive patients [HR, 1.58; 95% confidence interval (CI), 1.11-2.25)]. This prognostic value was confirmed in multivariate analysis (adjusted HR for death, 1.51; 95% CI, 1.04-2.21; P = 0.031) with a bootstrapping validation procedure. TUBB3 expression was associated with nonresponse to chemotherapy (adjusted HR, 1.31; 95% CI, 1.01-1.70; P = 0.044) but had no predictive value (taxane vs. gemcitabine). Taking account of these clinical findings, we further investigated TUBB3 expression in isogenic human bronchial cell lines only differing by K-Ras gene status and assessed the effect of K-Ras short interfering RNA (siRNA) mediated depletion, cell hypoxia, or pharmacologic inhibitors of K-Ras downstream effectors, on TUBB3 protein cell content. siRNA K-Ras knockdown, inhibition of RAF/MEK (MAP-ERK kinase) and phosphoinositide 3-kinase (PI3K)/AKT signaling, and hypoxia were shown to downregulate TUBB3 expression in bronchial cells. This study is the first one to identify K-Ras mutations as determinant of TUBB3 expression, a chemoresistance marker. Our in vitro data deserve studies combining standard chemotherapy with anti-MEK or anti-PI3K drugs in patients with TUBB3-overexpressing tumors.

Differential gene expression triggered by highly cytotoxic alpha-emitter-immunoconjugates in gastric cancer cells

Immunoconjugates composed of the alpha-emitter (213)Bi and the monoclonal antibody d9MAb specifically target HSC45-M2 gastric cancer cells expressing mutant d9-E-cadherin. These conjugates efficiently killed tumor cells in a nude mouse peritoneal carcinomatosis model. To elucidate the molecular responses of HSC45-M2 cells to alpha-emitter irradiation, whole genome gene expression profiling was performed. For that purpose HSC45-M2 cells were incubated with lethal doses of (213)Bi-d9MAb. RNA was isolated at 6, 24 and 48 h after irradiation, transcribed into cDNA and hybridized to whole genome microarrays. Results of microarray analysis were validated using RTQ-PCR showing correspondence of approximately 90%. Following incubation with (213)Bi-d9MAb, 682-1125 genes showed upregulation and 666-1278 genes showed downregulation at one time point, each. Eight genes appeared upregulated and 12 genes downregulated throughout. Molecular functions and biological processes of differentially expressed genes were categorized according to the PANTHER database. Following (213)Bi-d9MAb irradiation also a time-dependent shift in terms of overrepresentation of biological processes was observed. Among the genes showing continuous upregulation, COL4A2, NEDD9 and C3 have not been associated with the cellular response to high LET radiation so far. The same holds true for WWP2, RFX3, HIST4H4 and JADE1 that showed continuous downregulation. According to PANTHER, three of the consistently upregulated (ITM2C, FLJ11000, MSMB) and downregulated (HCG9, GAS2L3, FLJ21439) genes, respectively, have not been associated with any biological process or molecular function so far. Thus, these findings revealed interesting new targets for selective elimination of tumor cells and new insights regarding response of tumor cells to alpha-emitter exposure.

Noscapine and diltiazem augment taxol and radiation-induced S-phase arrest and clonogenic death of C6 glioma in vitro

BACKGROUND

Radiation therapy after surgical resection is the approved treatment of gliomas, and survival benefits are reported with taxane-based chemotherapy. We investigated whether these regimes could be augmented with blood-brain barrier permeable drugs, N and D. Noscapine is an opioid antitussive, which acts anti cancer via blocking microtubule dynamics. Diltiazem is a calcium channel-blocking cardiac antiarrythmic, which also blocks tumor growth and P-glycoprotein.

METHODS

Effects of N (11.1 micromol/L), D (11.1 micromol/L), and T (11.7 micromol/L) were monitored in C6 glioma cells via S phase, colony formation, and fine structure analysis.

RESULTS

Taxol depleted S phase from 35.2% to 12.2%. Both N and D synergistically augmented T-mediated S-phase depletion, and they also effectively reduced colonies, which were more potent by N by 49%. Taxol reduced colonies by 98%, and there were almost no surviving colonies in copresence of T with either N or D. Colony reduction by radiotherapy was increased strongly by T and significantly by N. Taxol and radiation profoundly increased number of mitochondria. Both D and N suppressed this increase via myelinosis and autophagy.

CONCLUSION

Noscapine and D should be further tested in animal models because of their potential and already-present clinical applicability.

Differential Expression of Proteins in Response to Ceramide-Mediated Stress Signal in Colon Cancer Cells by 2-D Gel Electrophoresis and MALDI-TOF−MS

Comparative cancer cell proteome analysis is a strategy to study the implication of ceramides in the transmission of stress signals. To better understand the mechanisms by which ceramide regulate some physiological or pathological events and the response to the pharmacological treatment of cancer, we performed a differential analysis of the proteome of HCT-116 (human colon carcinoma) cells in response to these substances. We first established the first 2-dimensional map of the HCT-116 proteome. Then, HCT116 cell proteome treated or not with C6-ceramide have been compared using two-dimensional electrophoresis, matrix-assisted laser desorption/ionization-mass spectrometry and bioinformatic (genomic databases). 2-DE gel analysis revealed more than fourty proteins that were differentially expressed in control cells and cells treated with ceramide. Among them, we confirmed the differential expression of proteins involved in apoptosis and cell adhesion.

Heterogeneity of radiation induced apoptosis in Ewing Tumor cell lines characterized on a single cell level

The objective of this study was to investigate heterogeneity of radiation induced apoptosis on a single cell level. Two Ewing tumor cell lines were characterized in vitro before and 24 and 72 h after radiation with 5 Gy by multiparametric flow cytometry. Annexin V, 7-AAD and fluorescence conjugated antibodies that were directed against HLA-ABC, CD11a and CD62L were used. Based on these markers radiation induced apoptosis was quantified, multiple apoptotic subpopulations were identified and a characteristic individual apoptotic profile was characterized. The characterization of HLA-ABC, CD11a and CD62L was informative to detect subpopulations of apoptotic cells. The observed heterogeneity and the identification of multiple apoptotic subpopulations reflect the complexity and diversity of biology of radiation induced cell death. This might be an indication for co-existing apoptotic pathways or it might represent sequential steps of the apoptotic cascade.

Reasons to reconsider the significance of apoptosis for cancer therapy

In recent years, the significance of apoptosis as a process in cell loss from normal tissue and tumours has been critically reviewed. In addition, the general lack of a correlation between radiation or drug-induced apoptosis and cell survival responses (using the clonogenic assay) in tumour cells has been demonstrated. Several different reasons have been discussed by other authors. It is the purpose of this review to argue that there are many different forms of cell death (terminal differentiation, micronucleation, mitotic catastrophe or multinucleation) that, like apoptosis, are regulated by the cell. In this context, apoptosis was the first cell death mechanism associated with active involvement of the cell (signal transduction). Furthermore, a large variety of different in vitro and a few in vivo models published so far show that the form of cell death can shift from, for example, mitotic catastrophe to apoptosis. The shift appears to be a general principle and depends on the cell model examined, the stressor type and the stressor intensity. These considerations help to explain the absence of a simple link between apoptosis and clonogenicity and suggest how to overcome that limitation, which has implications for the significance of apoptosis where the diagnosis and prognosis of cancer are concerned.

Expression of interferon inducible genes following Hantaan virus infection as a mechanism of resistance in A549 cells

Hantaan virus (HTN) is a causative agent of hemorrhagic fever with renal syndrome (HFRS). Little is known of its pathogenesis or the molecular mechanisms underlying resistance to HTN infection. In the present study, DNA microarray technology was used to monitor changes in mRNA levels after HTN infection, to elucidate resistance mechanisms to viral infection by understanding virus-host interactions. We found that several interferon (IFN)-inducible genes were up-regulated in host cells infected with HTN. According to previous available data, IFNs have been reported to be inhibitory, but their mode of action has not been yet clear. In this study, the 2',5'-oligoadenylated synthetase (OAS) and Mx1 genes, not a double-stranded RNA-dependent protein kinase R (PKR), of the IFN response pathways are associated with antiviral activity during HTN infection. Furthermore, A549 cells treated with IFN-alpha were protected against HTN infection. Taken together, these results confirmed that IFN plays a role in cellular defenses against HTN infection at an early stage of the infection and revealed the resistance mechanism for HTN infection.