Wilms tumor is the most prevalent malignant solid tumor in children's urology, and the exact pathophysiology is unknown [30]. Despite advances in clinical therapy for WT, overall survival has not increased considerably, which can be related to a paucity of molecular markers for successful diagnosis and treatment. As a result, it is critical to investigate WT molecular markers in order to increase patient survival. Researchers may now integrate several bioinformatics methodologies to extensively investigate the main pathophysiology and clinical diagnosis or prognosis of many diseases at the molecular level, thanks to the fast growth of diverse bioinformatics databases and high-throughput studies [31]. Therefore, the integration of RNA sequencing data and mining in the database has become an important means to explore the pathogenesis of WT and speculate the possible markers for diagnosis and treatment.
In this study, we integrated and analyzed the high-throughput sequencing data of WT tissues and adjacent normal tissues, and found that most of the differential genes were up-regulated. GO and KEGG pathway analysis showed that DEGs were enriched in multiple pathways related to malignant biology, including ‘DNA replication’, ‘cell cycle’. To further identify key genes that play important roles, we established a PPI network based on the STRING database and screened 10 HUB genes. CCNB1 was found to be a risk factor for poor prognosis in WT patients by univariate COX analysis. Multifactorial analysis similarly demonstrated that this gene was an independent risk factor. This suggests a potential biological role for CCNB1 in WT progression. It has been shown that CCNB1 is a prognostic factor for overall survival and metastasis-free survival in breast cancer [32]. Several studies have confirmed that CCNB1 can be used as a diagnostic or prognostic biomarker for rhabdomyosarcoma, hepatocellular liver cancer, and meningioma [33–35]. Other studies have found that CCNB1 is closely associated with tumour progression and is highly expressed in tumour tissue [36]. Critically, our results of CCNB1 validation from transcriptome and protein levels and combined with clinicopathological information showed that CCNB1 was significantly highly expressed in WT. Functional experiments confirmed that silencing CCNB1 could inhibit the proliferation, invasion, and migration of WT cells, suggesting a crucial role of this gene in WT. Interestingly, it has been reported that the high expression of CCNB1 has carcinogenic effects in different cancers, including renal, breast, pancreatic, hepatocellular, and cervical cancer [37–40]. Several studies have shown that CCNB1 is a potential target for tumour intervention [41, 42]. CCNB1 has been reported to be considered other potentially useful genes for targeting hepatocellular carcinoma [43, 44]. Therefore, it is speculated that this gene may be a potential key therapeutic target for WT.
The cell cycle-related factor CCNB1 belongs to the family of cell cycle proteins [45]. It is well known that one of the distinguishing features of cancer is cell cycle dysregulation, leading to the unrestricted proliferation of cancer cells [46, 47]. In this study, GSEA enrichment analysis suggested that the gene promoted tumour progression by regulating the cell cycle, and further experiments proved that silencing the gene caused cell cycle G2 arrest and apoptosis. These findings encourage us to speculate that CCNB1 is essential for cell cycle progression and proliferation. To sum up, CCNB1 may regulate WT tumour progression through the cell cycle pathway.
Cancer patients usually have a large number of T cells, but most of them have lost their function [48]. One study found that CCNB1 caused T cell-dependent antibody responses in patients with cancer and precancerous lesions, suggesting that this gene is an important player in the immune control of tumour growth [49]. In addition, CCNB1, which is aberrantly expressed in patients with breast, lung, head, and neck cancers, can be recognized by antibodies and T cells as tumour antigens [50]. CCNB1 was discovered by Kao et al as a common human epithelial tumor-associated antigen recognized by T lymphocytes [51]. Latner et al [52] elucidated the enhanced expression of CCNB1 in virus-specific memory CD8+ T cells. It is worth noting that another important finding of our study is that CCNB1 is associated with immune scores and multiple immune cell infiltration levels. Single gene GSEA analysis suggests that the gene may be involved in the regulation of a variety of key immune cells, which may affect tumour immunity and lead to poor prognosis and can be used as an important indicator of cancer prognosis.
We demonstrated that CCNB1 is a promising prognostic marker and potential therapeutic target for WT by high-throughput sequencing combined with bioinformatics analysis and experimental validation. Despite the large sample bioinformatics analysis and clinical sample validation performed in this study, certain limitations remain: First, our prognostic analysis and model are based on a public cohort, and retrospective innate characteristics hinder clinical applicability. Therefore, prospective studies are needed for further validation before clinical application. Second, the downstream mechanism by which CCNB1 exerts its oncogene function remains unclear requiring further in vivo and in vitro experiments for validation. Third, the immune regulatory function of this gene in the tumour microenvironment is based on bioinformatics analysis, and the exact mechanism needs to be further explored.
In conclusion, our findings imply that CCNB1 is a significant prognostic biomarker and a possible therapeutic target for Wilms tumor.