Uterine leiomyosarcoma is a common aggressive malignant tumor[11], originating from the muscular layer, characterized by early metastasis, poor prognosis, high distant recurrence rate [12], and limited treatment options. Its morphological and molecular characteristics cannot be identified by current clinical diagnostic tests, so it cannot be determined whether it is benign or malignant before surgery, and there is a risk of hidden malignant tumor during surgery[13]. The diagnosis of ULMS relies primarily on histology, and there is no specific molecular gene marker. Therefore, it is necessary to find specific targets for diagnosis and treatment.
In this study, we integrated gene expression profiles from two datasets (GSE68295 and GSE64763) and analyzed these datasets using R (4.2.2). The limma R package was used to identify 2286 DEGs, including 59 up-regulated genes and 83 down-regulated genes. The 10 genes most significantly upregulated at the peak were RUNDC3B, RAMP3, TSPAN7, SLCO2A1, JAM2, WT1, UBL3, PGR, EPS8, and KANK3. The top 10 genes significantly downregulated were TOP2A, ASF1B, CEP55, CCNB1, BUB1, CDK1, PLK1, GGH, AURKB, KIAA0101. The GO and KEGG enrichment analysis was mainly related to cell division and cell cycle, suggesting the potential role of GO and KEGG in inducing tumorigenesis and metastatic behavior in stratified cells. A PPI network of DEGs encoded proteins was constructed using MCODE to screen for hot spot modules, where the highest scoring modules included 24 closely related genes including ARHGAP11A, AURKA, CCNB1, KIAA0101, PLK1, BIRC5, BUB1, AURKB, KNTC1, KPNA2, CHEK1, DTL, HELLS, KIFC1, CEP55, TOP2A, CDK1, ASF1B, MCM5, ORC6. GINS2, CDC25A, TK1 and CHEK2 are genes that are downregulated. The top 10 highest scoring Hub genes were screened, among which CDK1, CCNB1 and BUB1 play unique roles in the pathogenesis of ULMS and are involved in the transition from UL to ULMS.
In the UL vs. ULMS comparison, the differentially expressed genes are mainly concentrated in the cell division pathway, highlighting the role of the cell cycle in the myeloma-to-sarcoma transition. The results of this study confirm that the cell cycle can transform these benign myomas into aggressive malignant leiomyosarcoma. The analysis revealed changes in the expression of genes that encode these pathways, leading to abnormal cell proliferation and an increased risk of cancer metastasis. Histological diagnosis of ULMS includes histological atypia, tumor cell necrosis, and increased mitotic rate [14]. In addition, ADAMS et al. [15] demonstrated high expression of cell cycle genes in uterine leiomyosarcoma. Meanwhile, WEST et al. [16] found that leiomyosarcoma showed cell cycle inhibition, cell-cell contact inhibition, and enrichment of DNA replication pathways. These findings are consistent with the results of this study.
Activation of cyclin dependent kinase 1 (CDK1) is required for the transition from the S phase to mitosis. CDK1 is essential for cell division by regulating G2/M phase and mitosis [17]. CDK1 inhibitors induce DNA repair inhibition and cell cycle regulation of cell sensitivity to DNA damage during G2/M [18]. Cyclin B1/cyclin dependent kinase 1 (CCNB1/CDK1) is a key mediator of mitosis. During mitosis, autophagy is inhibited, and autophagy is involved in cytokinesis and mesomeric degradation [19], and the inhibitory effect decreases at the end of cell stage and cytokinesis [20]. PI3K and mTORC1 involved in CCNB1/CDK1 are also inhibited during mitosis [21]. Therefore, competing mTORC1/2 inhibitors such as AZD8055 have been used to inhibit mitotic phosphorylation of proteins [20]. Meanwhile, PI3K (p110CAAX) inhibitors can inhibit CCNB1 transcription, leading to cytokinesis failure [22]. In addition, YING et al. [23] confirmed in vitro experiments that inhibition of CDK1 activity could induce apoptosis and cause G2/M phase arrest of the cell cycle of endometrial cancer cells. Overexpression of CDK1 in adrenal cortical cancer cell lines promotes proliferation and induces epithelial-mesenchymal transformation (EMT), while knockdown of CDK1 expression inhibits the growth of ACC cell lines [24]. Dihydro artemisinin targets are mainly enriched in cell cycle related pathways and can bind to CDK1/CCNB1 complex to inhibit the activation of CDK1/CCNB1 signal transduction and inhibit the progression of colorectal cancer cells [25]. CDK1 and CCNB1 gene clusters can provide potential therapeutic targets and prognostic biomarkers for breast cancer patients [26]. BUB1 is a kinase for examining the spindle components, monitoring the attachment of mitotic kinetosomes and maintaining high fidelity of mitotic chromosome separation [27]. BUB1 induced by CDK1 is a major motorist in mitosis [28]. It was found that the expression of BUB1 [29] was increased in neuroblastoma patients, which was negatively correlated with host immune infiltration, and could be used as a prognostic marker. It is therefore suspected that the use of CDK1 and its pathway inhibitors may be effective in reducing the growth and invasion of sarcoma tissue.
The use of the ssGSVA tool for 28 immune cells in this study is an aspect not previously mentioned. We evaluated the association of 10 Hub genes with immune cells infiltration. Activated CD10 T cells, activated CD20 T cells, type 20 T helper cells, and type 28 T helper cells are the top four cell types that are most closely related to the central genes and exist in small amounts in sarcoma tissues. Of these, CDK1 showed the highest correlation with activated CD10 T cells. ZOU et al. [30] found that CDK1, CCNB1 and CCNB2 are potential prognostic biomarkers of hepatocellular carcinoma and positively correlate with levels of CD4 T cells, CD8 T cells, neutrophils, macrophages and dendritic cells. BUB1 is highly expressed in the immune microenvironment, and CD4 T cells and macrophages of BUB1 mRNA are associated with good survival outcomes in patients with gastric cancer [31]. The above results suggest that CDK1 and BUB1 are closely related to immune infiltration, and immune cells infiltration was a favorable prognostic factor. There is a close interplay between the immune inflammatory response and the development of uterine leiomyosarcoma.
Now the evolving field of molecular biology has revealed the potential role of a variety of novel therapies, including targeted therapies and immunotherapies, as important components of combination therapies for refractory diseases. This study provides useful insights for proposing clinical strategies for multipoint targeted therapy of tumor cells, such as using CDK1 inhibitors, pathway multipoint gene synergistic inhibitors, and ATP-binding site selective inhibitors [32]. In addition, immunotherapy strategies for leiomyosarcoma are under active investigation.