FOXS1 acts as an oncogene and induces EMT through FAK/PI3K/AKT pathway by upregulating HILPDA in prostate cancer.

Prostate cancer (PCa) is a widespread global health concern characterized by elevated rates of occurrence, and there is a need for novel therapeutic targets to enhance patient outcomes. FOXS1 is closely linked to different cancers, but its function in PCa is still unknown. The expression of FOXS1, its prognostic role, clinical significance in PCa, and the potential mechanism by which FOXS1 affects PCa progression were investigated through bioinformatics analysis utilizing public data. The levels of FOXS1 and HILPDA were evaluated in clinical PCa samples using various methods, such as western blotting, immunohistochemistry, and qRT-PCR. To examine the function and molecular mechanisms of FOXS1 in PCa, a combination of experimental techniques including CCK-8 assay, flow cytometry, wound-healing assay, Transwell assay, and Co-IP assay were employed. The FOXS1 expression levels were significantly raised in PCa, correlating strongly with tumor aggressiveness and an unfavorable prognosis. Regulating FOXS1 expression, whether upregulating or downregulating it, correspondingly enhanced or inhibited the growth, migration, and invasion capabilities of PCa cells. Mechanistically, we detected a direct interaction between FOXS1 and HILPDA, resulting in the pathway activation of FAK/PI3K/AKT and facilitation EMT in PCa cells. FOXS1 collaborates with HILPDA to initiate EMT, thereby facilitating the PCa progression through the FAK/PI3K/AKT pathway activation.

Forkhead Box S1 mediates epithelial-mesenchymal transition through the Wnt/ß-catenin signaling pathway to regulate colorectal cancer progression.

BACKGROUND: Recent studies have shown that the fox family plays a vital role in tumorigenesis and progression. Forkhead Box S1 (FOXS1), as a newly identified subfamily of the FOX family, is overexpressed in certain types of malignant tumors and closely associated with patient's prognosis. However, the role and mechanism of the FOXS1 in colorectal cancer (CRC) remain unclear. METHOD: FOXS1 level in CRC tissues and cell lines was analyzed by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemistry (IHC) was used to detect the relationship between FOXS1 expression and clinicopathological features in 136 patients in our unit. The expression of FOXS1 was knocked down in CRC cells using small interfering RNA (siRNA) technology. Cell proliferation was assessed by CCK8 assay, colony formation, and 5-Ethynyl-20-deoxyuridine (EdU) incorporation assay. Flow cytometry detected apoptosis and wound healing, and Transwell assays determined cell migration and invasion. Western blotting was used to detect the levels of proteins associated with the Wnt/ß-catenin signaling pathway. Then, we used short hairpin RNA (shRNA) to knock down FOXS1 to see the effect of FOXS1 on the proliferation, migration, invasion, and metastasis of CRC cells in vivo. Finally, we investigated the impact of Wnt activator LiCl on the proliferation, migration, invasion, and metastasis of CRC cells after FOXS1 knockdown. RESULT: Compared to those in normal groups, FOXS1 overexpressed in CRC tissues and CRC cells (P < 0.05). Upregulation of FOXS1 association with poor prognosis of CRC patients. si-FOXS1 induced apoptosis and inhibited proliferation, migration, invasion, the epithelial-mesenchymal transition (EMT), and the Wnt/ß-catenin signaling pathway in vitro; sh-FOXS1 inhibited the volume and weight of subcutaneous xenografts and the number of lung metastases in vivo. LiCl, an activator of Wnt signaling, partially reversed the effect of FOXS1 overexpression on CRC cells. CONCLUSION: FOXS1 could function as an oncogene and promote CRC cell proliferation, migration, invasion and metastasis through the Wnt/ßcatenin signaling pathway, FOXS1 may be a potential target for CRC treatment.

Overexpression of FOXS1 in gastric cancer cell lines inhibits proliferation, metastasis, and epithelial-mesenchymal transition of tumor through downregulating wnt/ß-catenin pathway.

BACKGROUND: Expression of forkhead box (FOX) superfamily members has been shown to be decreased in cancer, which was linked to poor prognosis of patients. The aim of this study was to investigate the expression of a new FOX superfamily member, FOXS1, in gastric cancer, and the influence of FOXS1 overexpression on the tumorigenesis of gastric cancer cells. The underlying molecular mechanism was also investigated. MATERIALS AND METHODS: FOXS1 expression levels were firstly measured in 15 paired gastric cancer and peritumor tissue using quantitative polymerase chain reaction or immunohistochemistry. Secondly, FOXS1 overexpression models were established in two gastric cancer cell lines (SNU-216 and AGS) and FOXS1 knockdown model was established in SNU-638 gastric cancer cell line. Markers for cell proliferation, metastasis, cell cycle status, and wnt/ß-catenin pathway were evaluated. Influence of FOXS1 overexpression on tumorigenesis was further evaluated in xenograft model. RESULTS: Expression of FOXS1 was significantly decreased in gastric cancer tissue in both messenger RNA and protein levels, compared with peritumor tissue. Our results showed that compared to cell lines transfected with negative control, gastric cancer cell lines with FOXS1 overexpression showed suppressed cell proliferation, metastasis, and increased ratio of G0/G1 phase. Xenograft model also showed suppressed tumor growth in FOXS1 overexpression group. Epithelial-mesenchymal transition was also inhibited when FOXS1 was overexpressed, which was indicated by an increase of E-cadherin expression and decrease in vimentin expression. Further investigation showed that expression of ß-catenin was decreased, together with decreased expression in downstream signaling factors, c-Myc and cyclin-D1 in FOXS1 overexpression cell lines. On the other hand, knockdown of FOXS1 showed opposite trends in the changes of those markers for cell proliferation, metastasis, cell cycle status, and wnt/ß-catenin pathway, compared with FOXS1 overexpression. CONCLUSION: In conclusion, the present study showed that FOXS1 expression is downregulated in most GC cases in our cohort, and this loss of expression may promote cell proliferation and metastasis through upregulation of wnt/ß-catenin pathway.

FOXS1 promotes prostate cancer progression through the Hedgehog/Gli1 pathway.

BACKGROUND: Prostate cancer (PCa) remains the most common malignant tumor in men, and the clinical treatment still faces many challenges. Several molecular biomarkers of PCa progression have been reported, however, whether FOXS1 can serve as a new biomarker in PCa remains unknown. METHODS: FOXS1 and Gli1 expression was assessed by RT-qPCR and western blot. The binding and regulation roles between FOXS1 and Gli1 were confirmed by Co-IP and ubiquitination assays. Cell viability, proliferation, apoptosis, migration, invasion and EMT progress were assessed through CCK-8, colony formation, flow cytometry, wound-healing, transwell and western blot assays, respectively. In vivo nude mice tumorigenesis model was also conducted to verify PCa growth. RESULTS: FOXS1 was upregulated in the PCa TCGA dataset and cells. High FOXS1 level was correlated with PCa patients' worse tumor stage and shorter survival. FOXS1 knockdown inhibited PCa cell proliferation, invasion, migration, EMT and tumor growth while increased cell apoptosis. Furthermore, FOXS1 knockdown decreased the inactivation of Hedgehog (Hh) pathway. FOXS1 bind to Gli1 and decreased the ubiquitination of Gli1, which resulted in the upregulation of Gli1. Besides, both Gil1 overexpression and Hh signal activation reversed the suppression function of FOXS1 silencing on PCa growth and metastasis. CONCLUSION: FOXS1 bind and stabilized Gli1 by blocking Gli1 ubiquitination, thereby activating Hh signaling to promote PCa cell growth and metastasis.

FOXS1 Promotes Tumor Progression by Upregulating CXCL8 in Colorectal Cancer.

Background: Forkhead box S1 (FOXS1) is a member of the forkhead box (FOX) transcriptional factor superfamily. The biological roles and underlying regulatory mechanism of FOXS1 in CRC remain unclear. Methods: Bioinformatics analysis, Western blotting, real-time PCR, and immunohistochemistry (IHC) were used to detect the expression FOXS1 in CRC. MTT assay, transwell assay, human umbilical vein endothelial cell tube formation assay, and chicken chorioallantoic membrane assay were performed to investigate the effects of FOXS1 on proliferation, invasion, and angiogenesis. Additionally, tumor formation assay and orthotopic implantation assay were used to investigate the effects of FOXS1 on tumor growth and metastasis in vivo. Furthermore, gene set enrichment analysis (GSEA) was used to analyze the correlation between FOXS1 and EMT or angiogenesis. The correlation between FOXS1 and CXCL8 expression was analyzed in clinical CRC samples using IHC. Results: The results showed that FOXS1 expression was upregulated in CRC tissues compared with adjacent normal intestine tissues. A high FOXS1 expression is positively correlated with poor survival. FOXS1 promoted the malignant behavior of CRC cancer cells in vitro, including proliferation, invasion, and angiogenesis. In addition, FOXS1 promoted tumor growth and metastasis in nude mice. Mechanistically, FOXS1 upregulated the expression of C-X-C motif chemokine ligand 8 (CXCL8) at the transcriptional level. Knockdown of CXCL8 blocked FOXS1 induced the enhancement of the EMT and angiogenesis. GSEAs in public CRC datasets revealed strong correlations between FOXS1 expression and EMT marker and angiogenesis markers. IHC showed that FOXS1 expression was positively correlated with CXCL8 expression and CD31 expression in clinical CRC samples. Conclusion: The results suggest that FOXS1 promotes angiogenesis and metastasis by upregulating CXCL8 in CRC. Interference with the FOXS1/CXCL8 axis may serve as a potential therapeutic target for the treatment of metastatic CRC.

Pan-Cancer Analysis Predicts FOXS1 as a Key Target in Prognosis and Tumor Immunotherapy.

PURPOSE: Only a few studies have reported the role of FOXS1, a transcriptional factor, in the tumor development process. In this article, we investigate the function of FOXS1 in distinct neoplastic development and the tumor immune microenvironment (TIME). PATIENTS AND METHODS: The latent roles of FOXS1 in various tumors were prospected based on TCGA, GTEx, CCLE, GEPIA2, cBioPortal, TIMER, ImmuCellAI databases, GSVA datasets, GSEA datasets, and R packages. The expression difference, gene alteration, clinical characteristics, prognostic values, biological mechanism, potential pathways, tumor microenvironment, and immune cell infiltration related to FOXS1 were appraised. RESULTS: FOXS1 was strongly expressed in pan-cancer, and this gene was associated with low survival rates. FOXS1 was linked to many pathways that are cancer-promoting and immune-related. The expression of this transcriptional factor in cancers was positively related to immune cell infiltration, especially M2-like macrophages and Treg cells. In addition to that, FOXS1 demonstrated a positive relationship with many immune-suppression genes, such as TGFB1 and ARORA2A. CONCLUSION: Our study identified an oncogenic effect of FOXS1, which may play a vital role as a prognosticative biological marker in pan-cancer. Exorbitant expression of FOXS1 is associated with high TAMs and Treg cells infiltration. These cells have an immunosuppressive function and promote the development of the immunosuppressive tumor microenvironment. The research of FOXS1 provided a potential drug target for tumor immunotherapy.

CD90low glioma-associated mesenchymal stromal/stem cells promote temozolomide resistance by activating FOXS1-mediated epithelial-mesenchymal transition in glioma cells.

BACKGROUND: The tumour microenvironment contributes to chemotherapy resistance in gliomas, and glioma-associated mesenchymal stromal/stem cells (gaMSCs) are important stromal cell components that play multiple roles in tumour progression. However, whether gaMSCs affect chemotherapy resistance to the first-line agent temozolomide (TMZ) remains unclear. Herein, we explored the effect and mechanism of gaMSCs on resistance to TMZ in glioma cells. METHODS: Human glioma cells (cell line U87MG and primary glioblastoma cell line GBM-1) were cultured in conditioned media of gaMSCs and further treated with TMZ. The proliferation, apoptosis and migration of glioma cells were detected by Cell Counting Kit-8 (CCK-8), flow cytometry and wound-healing assays. The expression of FOXS1 in glioma cells was analysed by gene microarray, PCR and Western blotting. Then, FOXS1 expression in glioma cells was up- and downregulated by lentivirus transfection, and markers of the epithelial-mesenchymal transformation (EMT) process were detected. Tumour-bearing nude mice were established with different glioma cells and treated with TMZ to measure tumour size, survival time and Ki-67 expression. Finally, the expression of IL-6 in gaMSC subpopulations and its effects on FOXS1 expression in glioma cells were also investigated. RESULTS: Conditioned media of gaMSCs promoted the proliferation, migration and chemotherapy resistance of glioma cells. The increased expression of FOXS1 and activation of the EMT process in glioma cells under gaMSC-conditioned media were detected. The relationship of FOXS1, EMT and chemotherapy resistance in glioma cells was demonstrated through the regulation of FOXS1 expression in vitro and in vivo. Moreover, FOXS1 expression in glioma cells was increased by secretion of IL-6 mainly from the CD90low gaMSC subpopulation. CONCLUSIONS: CD90low gaMSCs could increase FOXS1 expression in glioma cells by IL-6 secretion, thereby activating epithelial-mesenchymal transition and resistance to TMZ in glioma cells. These results indicate a new role of gaMSCs in chemotherapy resistance and provide novel therapeutic targets.

Forkhead Box S1 Inhibits the Progression of Hepatocellular Carcinoma.

INTRODUCTION: Forkhead box (FOX) superfamily members were recently shown to play important roles in tumor development and progression. Forkhead box S1 (FOXS1), a member of the FOX family, has been reported to be closely associated with malignant neoplasms. However, its expression and effect on hepatocellular carcinoma remain unclear. The aim of this study was to determine the expression and role of FOXS1 in hepatocellular carcinoma (HCC). METHODS: Real-time PCR, Western blot and immunohistochemistry assays were carried out to determine FOXS1 expression in HCC tissues and cells. The biological roles of FOXS1 in HCC were investigated using CCK-8, colony formation, transwell and wound healing. Additionally, the effect of FOXS1 on epithelial-mesenchymal transition (EMT) was investigated by Western blotting. Xenograft model was carried out to evaluate the effect of FOXS1 in vivo. RESULTS: In our study, we confirmed lower FOXS1 expression in HCC samples than in normal liver tissues by performing Western blotting, immunohistochemistry and real-time PCR assays. In addition, FOXS1 expression is strongly associated with the prognosis of patients with HCC. Overexpression of FOXS1 suppressed cell proliferation, colony formation, the epithelial-mesenchymal transition (EMT) and the hedgehog (Hh) signaling pathway in vitro and in vivo. SAG, an activator of Hh signaling, partially reversed the effect of FOXS1 overexpression on HCC cells. CONCLUSION: FOXS1 might suppress HCC cell proliferation, colony formation, and EMT by inhibiting the Hh signaling pathway, indicating that FOXS1 may be a promising biological target in HCC.

Identification of novel GLI1 target genes and regulatory circuits in human cancer cells.

Hedgehog (HH) signaling is involved in many physiological processes, and pathway deregulation can result in a wide range of malignancies. Glioma-associated oncogene 1 (GLI1) is a transcription factor and a terminal effector of the HH cascade. Despite its crucial role in tumorigenesis, our understanding of the GLI1 cellular targets is quite limited. In this study, we identified multiple new GLI1 target genes using a combination of different genomic surveys and then subjected them to in-depth validation in human cancer cell lines. We were able to validate >90% of the new targets, which were enriched in functions involved in neurogenesis and regulation of transcription, in at least one type of follow-up experiment. Strikingly, we found that RNA editing of GLI1 can modulate effects on the targets. Furthermore, one of the top targets, FOXS1, a gene encoding a transcription factor previously implicated in nervous system development, was shown to act in a negative feedback loop limiting the cellular effects of GLI1 in medulloblastoma and rhabdomyosarcoma cells. Moreover, FOXS1 is both highly expressed and positively correlated with GLI1 in medulloblastoma samples of the Sonic HH subgroup, further arguing for the existence of FOXS1/GLI1 interplay in human tumors. Consistently, high FOXS1 expression predicts longer relapse-free survival in breast cancer. Overall, our findings open multiple new avenues in HH signaling pathway research and have potential for translational implications.