Bladder cancer is the most common tumor of the urinary tract. Tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ), a gene encoding the 14-3-3ζ protein, has been observed to be frequently amplified in bladder cancer. However, the role of 14-3-3ζ in various types of cancer is controversial. With reproduction of The Cancer Genome Atlas database, we searched the correlation of YWHAZ expression with survival outcomes of multiple cancers in silico. Our results revealed that only in bladder cancer was there a positive survival trend with YWHAZ overexpression. To study its role in bladder cancer, YWHAZ was successfully downregulated by lentivirus in 5637 and T24 cells. MTT and colony-formation assays showed that YWHAZ downregulation increased cell proliferation. Wound healing and Transwell assays showed that YWHAZ downregulation enhanced cell migration and invasiveness. FACS analysis showed that YWHAZ induced cell cycle arrest, but not apoptosis. A xenograft tumor model revealed that YWHAZ knockdown enhanced tumor growth. Gene set enrichment analysis confirmed that the cell cycle pathway plays a vital role in the function of the YWHAZ gene. In conclusion, knockdown of YWHAZ promoted both in vitro and in vivo tumorigenesis in bladder cancer and may be a novel biomarker for bladder cancer deserving further study.

MDM2 proto‑oncogene, E3 ubiquitin protein ligase (MDM2) is a well‑known oncogene and has been reported to be closely associated with epithelial‑to‑mesenchymal transition (EMT). The present study first demonstrated that the expression levels of MDM2 were markedly increased in TGF‑β‑induced EMT using quantitative PCR and western blotting. In addition, MDM2 was demonstrated to be associated with pathological grade in clinical glioma samples by immunohistochemical staining. Furthermore, overexpression of MDM2 promoted EMT in glioma, lung cancer and breast cancer cell lines using a scratch wound migration assay. Subsequently, the present study explored the mechanism by which MDM2 promoted EMT and revealed that MDM2 induced EMT by upregulating EMT‑related transcription factors via activation of the B‑Raf signaling pathway through tyrosine 3‑monooxygenase activation protein ε using RNA sequencing and western blotting. This mechanism depended on the p53 gene. Furthermore, in vivo experiments and the colony formation experiment demonstrated that MDM2 could promote tumor progression and induce EMT via the B‑Raf signaling pathway. Since EMT contributes to increased drug resistance in tumor cells, the present study also explored the relationship between MDM2 and drug sensitivity using an MTT assay, and identified that MDM2 promoted cell insensitivity to silibinin treatment in an EMT‑dependent manner. This finding is crucial for the development of cancer therapies and can also provide novel research avenues for future biological and clinical studies.

The present study aimed to explore the mechanism by which the immune landscape of the tumor microenvironment influences bladder cancer. CIBERSORT and ssGSEA analyses revealed that M2 macrophages accounted for the highest proportion from 22 subsets of tumor‑infiltrating immune cells and were enriched in higher histologic grade and higher pathologic stage bladder cancer and 'basal' subtype of muscle invasive bladder cancer (MIBC). Kaplan‑Meier survival curve analysis indicated that patients with high numbers of infiltrating M2 macrophages had worse overall and disease‑specific survival rates. RNA sequencing and immunohistochemistry results indicated that M2 macrophages were enriched in MIBC and promoted angiogenesis. M2 macrophage infiltration was higher in bladder cancer tissues with mutant TP53, RB transcriptional corepressor 1, phosphatidylinositol‑4,5‑bisphosphate 3‑kinase catalytic subunit α, lysine methyltransferase 2A, lysine demethylase 6A and apolipoprotein B mRNA editing enzyme catalytic‑polypeptide‑like, but lower in tissues with mutant fibroblast growth factor receptor 3 (FGFR3), E74‑like ETS transcription factor 3, PC4 and SFRS1 interacting protein 1 and transmembrane and coiled‑coil domains 4. In addition, M2 macrophage infiltration was lower in the tissues with amplified FGFR3, erb‑b2 receptor tyrosine kinase 2, BCL2‑like 1, telomerase reverse transcriptase and tyrosine‑3‑monooxygenase/tryptophan‑5‑monooxygenase activation protein ζ, as well as in the tissues with deleted cyclin‑dependent kinase inhibitor 2A, CREB binding protein, AT‑rich interaction domain 1A, fragile histidine triad diadenosine triphosphatase, phosphodiesterase 4D, RAD51 paralog B, nuclear receptor corepressor 1 and protein tyrosine phosphatase receptor type D. Finally, seven micro (mi) RNAs (miR‑214‑5p, miR‑223‑3p, miR‑155‑5p, miR‑199a‑3p, miR‑199b‑3P, miR‑146b‑5p, miR‑142‑5p) which were expressed differentially in at least three mutant genes and were positively correlated with M2 macrophage infiltration as well as expressed highly in high grade bladder cancer were identified. Overall, the present study concluded that M2 macrophages are the predominant tumor‑infiltrating immune cell in bladder cancer and differentially expressed miRNAs due to cancer‑specific genomic alterations may be important drivers of M2 macrophage infiltration. These findings suggested that M2 macrophage infiltration may serve as a potential immunotherapy target in bladder cancer.