X-inactive specific transcript (XIST), it has been found, is abnormal expression in various neoplasms. This work aims to explore its potential molecular mechanisms and prognostic roles in types of malignancies. Methods: This research comprehensively investigated XIST transcription across cancers from Oncomine, TIMER 2.0 and GEPIA2. Correlations of XIST expression with prognosis, miRNAs, interacting protens, immune infiltrates, checkpoint markers and mutations of tumor-associated genes were also

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... analyzed by public databases. Results: Compared to normal tissues, XIST was lower in BRCA, COAD, LUAD, lymphoma and OV in Oncomine; In TIMER 2.0, XIST was decreased in BRCA, KICH, THCA and UCEC, but increased in KIRC and PRAD; In GEPIA2, XIST was down-regulated in CESC, COAD, OV, READ, STAD, UCEC and UCS. Public databases also showed that XIST was a good indicator of prognosis in BRCA, CESC, COAD, STAD, OV and so on, but a bad one in KIRC, KIRP and so on. From starBase, we found 29 proteins interacting with XIST, and identified 4 miRNAs, including miR-103a-3p, miR-107, miR-130b-3p and miR-96-5p, which might be sponged by XIST in cancers. Furthermore, XIST was linked with immune infiltration, especially T cell CD4+, and was related to over 20 immune checkpoint markers. In addition, XIST was associated with several tumor-associated gene mutations in some cancers. Conclusion: In summary, abnormal expression of XIST influenced prognosis, miRNAs, immune cell infiltration and mutations of tumor-associated genes across cancers, especially BRCA and colorectal cancer. More efforts should be made to detect potential molecular mechanisms of XIST in the carcinogenesis.