Presence of a small plasmid in clinical isolates of Streptococcus pneumoniae

Twenty-four of 63 enteric Gram-negative organisms (38.1%) which were isolated from 35 apparently healthy Nigerian students were found to have low trimethoprim resistance (MIC less than 1000 mg/l). These isolates were also found to be resistant to several other antibiotics and trimethoprim resistance was found to be transferable from 15 (62.5%) of the trimethoprim resistant organisms into E. coli EC 1005. It is likely that the high percentage of trimethoprim resistance encountered in this study is related to the high rate of resistance transfer which was observed.     

LncRNA TP73-AS1 enhances the malignant properties of pancreatic ductal adenocarcinoma by increasing MMP14 expression through miRNA -200a sponging

Pancreatic ductal adenocarcinoma (PDAC) is an invasive and aggressive cancer that remains a major threat to human health across the globe. Despite advances in cancer treatments and diagnosis, the prognosis of PDAC patients remains poor. New and more effective PDAC therapies are therefore urgently required. In this study, we identified a novel host factor, namely the LncRNA TP73-AS1, as overexpressed in PDAC tissues compared to adjacent healthy tissue samples. The overexpression of TP-73-AS1 was found to correlate with both PDAC stage and lymph node metastasis. To reveal its role in PDCA, we targeted TP73-AS1 using LnRNA inhibitors in a range of pancreatic cancer (PC) cell lines. We found that the inhibition of TP73-AS1 led to a loss of MMP14 expression in PC cells and significantly inhibited their migratory and invasive capacity. No effects of TP73-AS1 on cell survival or proliferation were observed. Mechanistically, we found that TP73-AS1 suppressed the expression of the known oncogenic miR-200a. Taken together, these data highlight the prognostic potential of TP73-AS1 for PC patients and highlight it as a potential anti-PDAC therapeutic target.     

MiR-150-5p靶向TP53对结直肠癌细胞侵袭和增殖的影响

摘要 目的：探索miR-150-5p靶向调控TP53基因对结直肠癌（colorectal cancer, CRC）在临床和生物学的相关性,研究miR-150-5p调控TP53基因在结直肠癌细胞增殖和侵袭病变中的作用。方法：收集临床手术切除并病理证实的结直肠癌患者的手术及血浆样本（结直肠癌和癌旁组织）60例,另选取癌旁正常粘膜10例,腺瘤30例。根据瘤体直径分为肿瘤＞5 cm（n=30）和≤5 cm（n=30）。qRT-PCR法测定样本中miR-150-5p表达,荧光素酶活性测定以确定TP53是否为miR-150-5p的靶基因。使用SW480细胞株,进行Transwell小室检测细胞侵袭能力,CCK-8检测细胞增值能力,对miR-150-5p进行生物信息学分析。结果：TP53是miR-150-5p的下游基因。癌组织及血浆中miR-150-5p表达量低于癌旁组织,直径＞5 cm瘤体中的miR-150-5p表达量显著低于直径≤5 cm瘤体,Ⅰ-Ⅱ期结直肠癌组织中的miR-150-5p表达显著高于Ⅲ-Ⅳ期（P＜0.05）。上调miR-150-5p后,细胞中TP53表达下降,下调miR-150-5p后,TP53表达升高;CCK-8增殖试验显示细胞中miR-150-5p过表达组抑制细胞增殖（P＜0.05）。结论：MiR-150-5p在结直肠癌组织和细胞中显著低表达,miR-150-5p通过靶向调节TP53抑制人CRC细胞的侵袭和增殖,有望成为结直肠癌治疗的新靶点。     

Killing of Escherichia coli K-12 by near-ultraviolet radiation in the presence of hydrogen peroxide: Role of double-strand DNA breaks in absence of recombinational repair

Near-ultraviolet (NUV) radiation killing of Escherichia coli K-12 can be enhanced by a sub-lethal concentration of hydrogen peroxide. This can be divided into a “RecA-dependent” and “RecA-independent” synergistic killing action. Stationary phase wild-type and 8 closely related repair-deficient mutants were examined for their NUV sensitivities in the presence and absence of H₂O₂. All exhibited the “RecA-independent” synergism; i.e., H₂O₂ enhanced NUV lethality when RecA repair was not operating. The “RecA-independent” synergism did not result from destruction of repair enzymes. Very few DNA—protein crosslinks could be detected following NUV plus H₂O₂ treatment. However, double-strand (DS) DNA breaks were produced, apparently by conversion of closely spaced single-strand (SS) breaks on opposite strands. The correlation between DS-break formation and lethality in wild-type and a polA mutant indicates that the RecA-independent synergistic killing results from the conversion of SS into lethal DS breaks.     

The ATP/2e ratio during photosynthesis in intact spinach chloroplasts.

Addition of ribose-5-phosphate to intact spinach chloroplasts in the absence of added P_i resulted in a conversion of part of the Benson-Calvin cycle into a linear sequence so that triose phosphate accumulated during CO₂ fixation stoichiometrically with the O₂ evolved (triose phosphate / O₂ ratio was 2.0). The fortunate consequence of this effect is that the $\text{A<font color="red">TP</font>}\text{2e}$ ratio may be calculated from the 3-phosphoglycerate and triose phosphate accumulated and the O₂ evolved. In this way the $\text{A<font color="red">TP</font>}\text{2e}$ ratio was shown to be 2.0, with cyclic or pseudocyclic phosphorylation contributing less than 9% to the total phosphorylation.     

Identification of dynamic signatures associated with smoking‐related squamous cell lung cancer and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a risk factor for the development of lung cancer. The aim of this study was to identify early diagnosis biomarkers for lung squamous cell carcinoma (SQCC) in COPD patients and to determine the potential pathogenetic mechanisms. The GSE12472 data set was downloaded from the Gene Expression Omnibus database. Differentially co‐expressed links (DLs) and differentially expressed genes (DEGs) in both COPD and normal tissues, or in both SQCC + COPD and COPD samples were used to construct a dynamic network associated with high‐risk genes for the SQCC pathogenetic process. Enrichment analysis was performed based on Gene Ontology annotations and Kyoto Encyclopedia of Genes and Genomes pathway analysis. We used the gene expression data and the clinical information to identify the co‐expression modules based on weighted gene co‐expression network analysis (WGCNA). In total, 205 dynamic DEGs, 5034 DLs and one pathway including CDKN1A, TP53, RB1 and MYC were found to have correlations with the pathogenetic progress. The pathogenetic mechanisms shared by both SQCC and COPD are closely related to oxidative stress, the immune response and infection. WGCNA identified 11 co‐expression modules, where magenta and black were correlated with the “time to distant metastasis.” And the “surgery due to” was closely related to the brown and blue modules. In conclusion, a pathway that includes TP53, CDKN1A, RB1 and MYC may play a vital role in driving COPD towards SQCC. Inflammatory processes and the immune response participate in COPD‐related carcinogenesis.     

Gaining insights into relevance across cancers based on mutation features of TP53 gene

The tumor suppressor gene TP53, one of the most frequently mutated genes, is recognized as the guardian of genome and can provide a significant barrier to neoplastic transformation and tumor progression. Traditional theory believes that TP53 mutations are equal among cancer types. However, to date, no study has explored the TP53 mutation profile from a holistic and systematic standpoint to discovery its relevance and feature with cancers. Mutation signature, an unbiased approach to identify the mutational processes, can be a potent indicator for exploring mutation-driven tumor occurrence and progression. In this research, several features such as hotspots, mutability and mutation signature of somatic TP53 mutations derived from 18 types of cancer tissues from cBioPortal were analyzed and manifested the organizational preference among cancers. Mutation signatures found in almost all cancer types were Signature 6 related to mismatch repair deficiency, and Signature 1 that reflects the natural decomposition of 5-methylcytosine into thymine associated with aging. Meanwhile, several signatures of TP53 mutations displayed tissue-selective. Mutations enriched in bladder, skin, lung cancer were associated with signatures of APOBEC activity (Signature 2 and 13), alkylating agents (Signature 11), and tobacco smoke (Signature 4), respectively. Moreover, Signature 4 and 29 associated with tobacco smoking or chewing found in lung, sarcoma, esophageal, and head and neck cancer may be related to their smoking history. In addition, several digestive cancers, including colorectal, stomach, pancreatic and esophageal cancers, showed the high correlation in context and mutation signature profiles. Our study suggests that the tissue-selective activity of mutational processes would reflect the tissue-specific enrichment of TP53 mutations and provides a new perspective to understand the relevance of diverse diseases based on the spectrum of TP53 mutations.