No abstract

Despite the development of various treatments, metastasis remains a significant problem with lung adenocarcinoma (ADC). The role and mechanism of epithelial splicing regulatory protein 1 (ESRP1), an epithelial-specific RNA binding protein, on promoting the invasion and metastasis of lung ADC remain to be fully elucidated. Immunohistochemical analysis in 125 human lung ADC tissue samples demonstrated that ESRP1 overexpression was inversely related to the presence of metastases, tumor size, and clinical stage of lung ADC. Impaired ESRP1 expression was also found to stimulate the invasion capacity of lung ADC cells both in vitro and in vivo. Functionally, overexpression of the ZEB1 gene decreased ESRP1 expression, and knockdown of the ZEB1 gene caused increased ESRP1 expression. On the basis of a gene array analysis, the expression of ESRP1 was associated with the regulation of the extracellular matrix. The expression of CD44 and fibroblast growth factor receptor, representatives that interact with the extracellular matrix, was studied. The CD44 subtypes promoted lung ADC cell invasion by regulating matrix metalloproteinase 2 expression. In conclusion, ESRP1 inhibits the invasion and metastasis of lung ADC and plays a role in regulating proteins involved in epithelial-to-mesenchymal transition.

Our previous work demonstrated that Epithelial Splicing Regulatory Protein 1 (ESRP1) could inhibit the progression of lung adenocarcinoma (ADC). When ESRP1 was upregulated, the interferon (IFN) pathway was activated and Interferon-stimulated gene 15 (ISG15) expression increased exponentially in our microarray result. In this study, we aim to explore the function of ISG15 and its interactions with ESRP1 and to provide new insights for ADC treatment. ISG15 expression in lung ADC tissues was determined by immunohistochemistry (IHC) staining. The effect of ISG15 on lung ADC progression was examined by in vitro and in vivo assays. The mechanism of action on ESRP1 regulating ISG15 was investigated using Western blotting, RT-qPCR, immunofluorescence staining, chromatin immunoprecipitation, and a dual luciferase reporter system. The ISGylation between ISG15 and ESRP1 was detected by co-immunoprecipitation. Patients with high ISG15 expression were associated with higher survival rates, especially those with ISG15 expression in the nucleus. In vitro and in vivo experiments showed that upregulation of ISG15 inhibited EMT in lung ADC. ESRP1 upregulated the expression of ISG15 through CREB with enriched ISG15 in the nucleus. Importantly, ISG15 promoted ISGylation of ESRP1 and slowed the degradation of ESRP1, which demonstrated that ESRP1 and ISG15 formed a positive feedback loop and jointly suppressed EMT of lung ADC. In conclusion, ISG15 serves as an independent prognostic marker for long-term survival in lung ADC patients. We have revealed the protective effect of ISG15 against lung ADC progression and the combinatorial benefit of ISG15 and ESRP1 on inhibiting EMT. These findings suggest that reconstituting ISG15 and ESRP1 may have the potential for treating lung ADC.

By scoring criterion, SEOCs were divided into 2 groups: synchronous primary endometrial and ovarian carcinoma group and single primary tumor with metastasis group. The analysis of clonality indicated that the case that scored 2 (S52) can be considered as synchronous primary endometrial and ovarian carcinomas. Scoring criteria of clinical pathology, along with the study of the WES, may further identify the classification of SEOCs.