Myofibrillogenesis Regulator-1 Regulates the Ubiquitin Lysosomal Pathway of Notch3 Intracellular Domain Through E3 Ubiquitin-Protein Ligase Itchy Homolog in the Metastasis of Non-Small Cell Lung Cancer

Myofibrillogenesis regulator-1 (MR-1) is a multifunctional protein involved in the development of various human tumors. The study is the first to report the promoting effect of MR-1 on the development and metastasis of non-small cell lung cancer (NSCLC). MR-1 is upregulated in NSCLC and positively associated with poor prognosis. The overexpression of MR-1 promotes the metastasis of NSCLC cells by stabilizing the expression of Notch3-ICD (NICD3) in the cytoplasm through enrichment analysis, in vitro and in vivo experimental researches. And Notch3 signaling can upregulate many genes related to metastasis. The stabilizing effect of MR-1 on NICD3 is achieved through the mono-ubiquitin lysosomal pathway and the specific E3 ubiquitin ligase is Itchy homolog (ITCH). There is a certain interaction between MR-1 and NICD3. Elevated MR-1 can affect the level of ITCH phosphorylation, reduce its E3 enzyme activity, and thus lead to reduce the ubiquitination and degradation of NICD3. Interference with the interaction between MR-1 and NICD3 can increase the degradation of NICD3 and impair the metastatic ability of NSCLC cells, which is a previously overlooked treatment option in NSCLC. In summary, interference with the interaction between MR-1 and NICD3 in the progression of lung cancer may be a promising therapeutic target.

Deterioration of Cycloserine in Drug Susceptibility Testing of Mycobacterium

Purpose

Cycloserine is an effective group C anti-tuberculosis drug. But the reliability and reproducibility of drug susceptibility tests (DST) for this drug cannot be guaranteed and provide poor clinical predictive values. However, DST of cycloserine in practice provides rough estimate of the drug resistance of Mycobacterium strains, there is practical need to clarify the problem of cycloserine in in vitro DST, and to explore solutions to overcome these limitations.

Methods

The effectiveness of serial cycloserine solutions incubated at 37°C for 1 to 29 days was tested using the Alamar Blue assay, and cycloserine in culture medium was analyzed by UPLC-MS.

Results

The data revealed that cycloserine itself continuously degraded in culture medium. This amount of degradation was sufficient to alter the minimum inhibitory concentration (MIC) value of Mycobacterium strains and therefore could not be ignored, although it was more stable than in phosphoric acid buffer.

Conclusion

The different test times and the degradation of cycloserine were responsible for the lack of agreements between the cycloserine DST methods and the low reliability of this in vitro test. By adjusting with the incubation time depended degradation ratio of cycloserine, more accurate MIC values may be obtained allowing for improved coincidence between in vitro experiment and clinic use. Furthermore, it can guide clinicians to carry out this anti-tuberculosis treatment more effectively and reliably.

Emergence of ST15 Klebsiella pneumoniae Clinical Isolates Producing Plasmids-Mediated RmtF and OXA-232 in China

BACKGROUND

RmtF, as 16S rRNA methyltransferase, leads to high-level resistance to aminoglycoside and is now barely reported.

METHODS AND RESULTS

Three rmtF-positive Klebsiella pneumoniae isolates, belonging to the pandemic clone sequence type 15, were isolated from children and coproduced bla OXA-232 and bla CTX-M-15. The rmtF gene was located on an IncFIB transformable plasmid of 128,536-bp and bla OXA-232 was on a 6141-bp ColKP3 plasmid, respectively.

CONCLUSION

Plasmids with rmtF found worldwide, shared relatively low similarity, and merely matched partly in their multidrug resistance region. Notably, clinical isolates coproducing rmtF and bla OXA-232 are gradually increasing in China.