Background: Long noncoding RNAs (lncRNAs) X inactivate-specific transcripts (XIST) have been found to be dysregulated in breast cancer (BC). Nevertheless, the influence and mechanism of XIST on BC progression remain largely undefined. Methods: The expression levels of XIST, miR-362-5p, and ubiquitin-associated protein 1 (UBAP1) mRNA were detected by quantitative real-time polymerase chain reaction. Cell proliferation, apoptosis, migration, and invasion abilities were determined using MTT assay, flow cytometry, and transwell assay, respectively. Targeted relationship between miR-362-5p and XIST or UBAP1 was validated by the dual-luciferase reporter assay. Western blot was performed to evaluate UBAP1 protein level. Xenograft mice model was established for the investigation of XIST in tumor growth.Results: The authors' data indicated that XIST and UBAP1 were downregulated in BC tissues and cells. XIST overexpression weakened BC cell proliferation, migration, invasion, and facilitated the apoptosis, and XIST silencing exerted opposite effect. Mechanistically, XIST directly interacted with miR-362-5p and miR-362-5p mediated the regulatory effects of XIST overexpression on BC cell malignant behaviors. UBAP1 was a direct target of miR-362-5p. MiR-362-5p exerted its regulatory effects on BC cell behaviors by UBAP1. Moreover, XIST modulated UBAP1 expression through acting a competing endogenous RNA of miR-362-5p. XIST overexpression mediated antiproliferation, antimigration, anti-invasion, and proapoptosis effects were abated by the restored expression of UBAP1 in BC cells. Furthermore, the upregulation of XIST hindered tumor growth in vivo. Conclusion:The current study suggested that XIST overexpression hampered BC cell progression in vitro and in vivo at least partially by targeting the miR-362-5p/UBAP1 axis, illuminating XIST as a promising therapeutic agent for BC management.

Background and aim: Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of nonsmall cell lung cancer with a poor prognosis. This study aimed to analyze the clinicopathological characteristics and survival outcomes among patients with PSC, lung squamous cell cancer (SCC), and lung adenocarcinoma (LAC), and to construct a competing risk nomogram for patients with PSC. Method: Data of 3 groups of patients diagnosed with PSC, SCC, or LAC from the surveillance, epidemiology, and end results (SEER) database between 1988 and 2015 were retrospectively reviewed. A 1:1 propensity score matching (PSM) analysis was used to balance the baseline data of patients. Independent risk factors associated with survival outcomes were screened by the least absolute shrinkage and selection operator and further determined by univariate and multivariate Cox proportional risk regression analyses. The overall survival (OS) of patients was evaluated by Kaplan–Meier analysis and compared with a log-rank test. The cumulative incidence function was used to estimate the 5-year probabilities of the cancer-specific mortality of PSC. A nomogram was constructed to illustrate the competing risk model to predict the 3- and 5-year OS, and corresponding concordance indexes (C-indexes) and calibration curves were used to assess and validate the competing risk nomogram. Results: A total of 2285 patients with PSC were included in this study. Compared with SCC and LAC patients, the Kaplan–Meier analysis showed that patients with PSC had a worse prognosis, with a median survival of 5 months (95% confidence interval [CI]: 5-6 months) and a 5-year OS rate of 15.3% (95% CI: 13.9%-16.9%). Similar outcomes were demonstrated after 1:1 PSM. Moreover, the competing risk model showed that age, T stage, M stage, tumor size, lymph node ratio (LNR), surgery, and chemotherapy were associated with PSC-specific mortality. The 5-year C-index of the nomogram was 0.718. Calibration curves illustrated that the nomogram was well-validated and had great accuracy. Conclusions: Patients with PSC had a worse survival outcome compared with SCC or LAC patients. Age, T stage, M stage, tumor size, LNR, surgery, and chemotherapy were associated with PSC-specific mortality. The competing risk nomogram displayed excellent discrimination in predicting PSC-specific mortality.