Sex-determining region of Y chromosome-related high-mobility-group box 2 in malignant tumors: current opinions and anticancer therapy

Novel characteristics for immunophenotype, FISH pattern and molecular cytogenetics in synovial sarcoma

As a rare and highly aggressive soft tissue sarcoma, the new immunophenotype, atypical FISH pattern and relevant molecular cytogenetics of synovial sarcoma (SS) remain less known, although it is characteristically represented by a pathognomonic chromosomal translocation t (X; 18) (p11.2; q11.2). Methodologically, the morphology was retrospectively analysed by using H&E staining, and immunohistochemical features were investigated by using markers that have been recently applied in other soft tissue tumors. Moreover, FISH signals for SS18 and EWSR-1 break-apart probes were examined. Finally, cytogenetic characteristics were analysed via RT-PCR and Sanger sequencing. Consequently, nine out of thirteen cases that were histologically highly suspected as SS were finally identified as SS via molecular analysis. Histologically, nine SS cases were divided into monophasic fibrous SS (4/9), biphasic SS (4/9) and poorly differentiated SS (1/9). Immunohistochemically, SOX-2 immunostaining was positive in eight cases (8/9) and PAX-7 immunostaining was diffusely positive in the epithelial component of biphasic SS (4/4). Nine cases showed negative immunostaining for NKX3.1 and reduced or absent immunostaining for INI-1. Eight cases showed typically positive FISH signalling for the SS18 break-apart probe, whereas one case exhibited an atypical FISH pattern (complete loss of green signalling, case 2). Furthermore, the SS18-SSX1 and SS18-SSX2 fusion genes were identified in seven cases and two cases, respectively. The fusion site in 8 out of 9 cases was common in the literature, whereas the fusion site in case 2 was involved in exon 10 codon 404 in SS18 and exon 7 codon 119 in SSX1 (which has not been previously reported), which notably corresponded to the complete loss of green signalling in the FISH pattern. Additionally, FISH analysis of the EWSR-1 gene in nine SS cases demonstrated aberrant signalling in three cases that were recognized as a monoallelic loss of EWSR-1 (1/9), an amplification of EWSR-1 (1/9) and a translocation of EWSR-1 (1/9). In conclusion, SS18-SSX fusion gene sequencing is obligatory for a precise diagnosis of SS when dealing with a confusing immunophenotype and atypical or aberrant FISH signalling for SS18 and EWSR-1 detection.

The function of SOX2 in breast cancer and relevant signaling pathway

OBJECTIVE

The purpose of this study was to explore the functional roles of SOX2 in the progression of breast cancer and relevant molecular mechanism.

METHODS

A total of 108 breast cancer patients were included, and breast cancer cell line MDA-MB-231 was selected for this research. Real time-qualitative polymerase chain reaction (RT-qPCR) was conducted to measure the expression level of SOX2 mRNA. MTT and Transwell assays were used to detected the proliferation, migration and invasion of breast cancer cells, respectively. Luciferase reporter assay was conducted to reveal the relationship of SOX2 with PTEN. Western blot was performed to detect the expressions of Wnt/β-catenin pathway-related proteins.

RESULTS

The expression of SOX2 mRNA was up-regulated in breast cancer tissues and cells (P < 0.001). SOX2 expression was significantly associated with TNM stage and lymph node metastasis of breast cancer patients (P < 0.05). SOX2 knockdown significantly inhibited the proliferation, migration and invasion of breast cancer cells (P < 0.05). PTEN was a direct target of SOX2. The inhibition of PTEN could significantly suppress the progression of breast cancer cells with SOX2 overexpression. SOX2 knockdown also inhibited the expressions of β-catenin, TCP-4, FZD7, C-myc and MMP-7 proteins. Moreover, PTEN knockdown reversed the results caused by SOX2 overexpression, that is, increased expressions of β-catenin, TCP-4, FZD7, C-myc and MMP-7 proteins (P < 0.05).

CONCLUSION

SOX2 promotes the progression of breast cancer through activating Wnt/β-catenin signaling pathway via regulating PTEN.

PHF20 collaborates with PARP1 to promote stemness and aggressiveness of neuroblastoma cells through activation of SOX2 and OCT4

The differentiation status of neuroblastoma (NB) strongly correlates with its clinical outcomes; however, the molecular mechanisms driving maintenance of stemness and differentiation remain poorly understood. Here, we show that plant homeodomain finger-containing protein 20 (PHF20) functions as a critical epigenetic regulator in sustaining stem cell-like phenotype of NB by using CRISPR/Cas9-based targeted knockout (KO) for high-throughput screening of gene function in NB cell differentiation. The expression of PHF20 in NB was significantly associated with high aggressiveness of the tumor and poor outcomes for NB patients. Deletion of PHF20 inhibited NB cell proliferation, invasive migration, and stem cell-like traits. Mechanistically, PHF20 interacts with poly(ADP-ribose) polymerase 1 (PARP1) and directly binds to promoter regions of octamer-binding transcription factor 4 (OCT4) and sex determining region Y-box 2 (SOX2) to modulate a histone mark associated with active transcription, trimethylation of lysine 4 on histone H3 protein subunit (H3K4me3). Overexpression of OCT4 and SOX2 restored growth and progression of PHF20 KO tumor cells. Consistently, OCT4 and SOX2 protein levels in clinical NB specimens were positively correlated with PHF20 expression. Our results establish PHF20 as a key driver of NB stem cell-like properties and aggressive behaviors, with implications for prognosis and therapy.

SOX2 Gene Amplification and Overexpression is Linked to HPV-positive Vulvar Carcinomas

SOX2 (SRY-related HMG-box 2) belongs to the SOX gene family of high-mobility transcription factors indispensably involved in gene regulation in pluripotent stem cells and neural differentiation. SOX2 copy number increases have been frequently reported in various types of squamous cell cancer. To better understand the effect of SOX2 aberrations on vulvar cancer phenotype and patient prognosis, we analyzed SOX2 copy number changes using fluorescence in situ hybridization and SOX2 expression by immunohistochemistry in 55 squamous cell carcinomas of the vulva. SOX2 amplification was found in 20.8% of tumors; 27.3% of vulvar carcinomas showed SOX2 protein overexpression. SOX2 amplification was correlated with SOX2 overexpression in our data set (P<0.01). Amplification of the SOX2 locus was associated with high tumor grade (P<0.05) and human papillomavirus (HPV) positivity (P<0.01). SOX2-amplified tumors showed more frequently a basaloid phenotype than nonamplified carcinomas. SOX2 protein overexpression was also correlated with basaloid phenotype and positive HPV status of vulvar carcinomas (P<0.05, each). SOX2 amplification and expression were not associated with patient overall survival. In conclusion, SOX2 copy number increases are detectable in a substantial proportion of high-grade HPV-positive vulvar carcinomas with basaloid differentiation. Our study provides further evidence for different molecular alterations in HPV-positive and HPV-negative vulvar carcinomas.

Stem cell transcription factor SOX2 in synovial sarcoma and other soft tissue tumors

BACKGROUND

SOX2 has gained considerable interest as a pluripotency inducing gene. Co-transfection of SOX2 together with NANOG, KLF4 and c-MYC into adult fibroblasts was able to generate pluripotent stem cells. SOX2 has been reported to be expressed in synovial sarcoma, a tumor being characterized by the SS18-SSX gene fusion forming part of the SWI/SNF chromatin remodeling complex that affects histone methylation. The role of SOX2 in this tumor type as well as other soft tissue tumor entities however is still poorly characterized. We analyzed SOX2 protein expression in soft tissue tumors. Alongside we tested Histone H3 expression (H3K27me3) in SOX2 positive cases to investigate this epigenetic mark and its correlation with the SOX2 status and clinicopathological parameters.

METHODOLOGY

In total, 60 samples of synovial sarcomas from the reference center for soft tissue tumors at the institute of pathology of the Jena University hospital were included into the study along with 343 other tissue tumors. Protein analysis was done by immunohistochemistry of tissue microarrays. All synovial sarcoma cases were confirmed by molecular testing using SS18 FISH break apart probes.

RESULTS

SOX2 reactivity was detectable in 35 synovial sarcoma cases (58.3%) while 25 (41.7%) were negative. Only 13 cases of the other 343 soft tissue tumors, varying from nodular fasciitis to undifferentiated pleomorphic sarcoma, revealed a SOX2 expression, 12 out of these were undifferentiated high grade sarcoma. There was no obvious correlation with the clinicopathological data. H3K27me3 immunohistochemistry of the synovial sarcoma cases revealed a high statistically significant correlation between SOX2 and H3K27me3 expression (p < 0,0005, Chi square test). Similar to SOX2, there was no correlation between H3K27me3 expression and tumor grade. Six SOX2 positive synovial sarcoma cases were analyzed by FISH using a SOX2/CEN3 dual color FISH probe. None of these cases revealed an amplification of the SOX2 gene.

CONCLUSION

The data confirms previous studies reporting SOX2 and H3K27me3 expression in synovial sarcoma and reveals that both biomarkers are related to each other. It strengthens the notion that the tumor type is driven by epigenetic processes similar to those that are operating in pluripotent stem cells. The relevance of these parameters in the pathway pathology of synovial sarcoma, i.e. the timing and dosing of SOX2 and H3K27me3 expression initiated by the SS18-SSX driver mutation together with the interplay of these events with other signaling pathways, cellular mechanisms and additional mutations in tumor progression, will require further studies.

BRCA1-IRIS overexpression promotes and maintains the tumor initiating phenotype: implications for triple negative breast cancer early lesions

Tumor-initiating cells (TICs) are cancer cells endowed with self-renewal, multi-lineage differentiation, increased chemo-resistance, and in breast cancers the CD44+/CD24-/ALDH1+ phenotype. Triple negative breast cancers show lack of BRCA1 expression in addition to enhanced basal, epithelial-to-mesenchymal transition (EMT), and TIC phenotypes. BRCA1-IRIS (hereafter IRIS) is an oncogene produced by the alternative usage of the BRCA1 locus. IRIS is involved in induction of replication, transcription of selected oncogenes, and promoting breast cancer cells aggressiveness. Here, we demonstrate that IRIS overexpression (IRISOE) promotes TNBCs through suppressing BRCA1 expression, enhancing basal-biomarkers, EMT-inducers, and stemness-enforcers expression. IRISOE also activates the TIC phenotype in TNBC cells through elevating CD44 and ALDH1 expression/activity and preventing CD24 surface presentation by activating the internalization pathway EGFR→c-Src→cortactin. We show that the intrinsic sensitivity to an anti-CD24 cross-linking antibody-induced cell death in membranous CD24 expressing/luminal A cells could be acquired in cytoplasmic CD24 expressing IRISOE TNBC/TIC cells through IRIS silencing or inactivation. We show that fewer IRISOE TNBC/TICs cells form large tumors composed of TICs, resembling TNBCs early lesions in patients that contain metastatic precursors capable of disseminating and metastasizing at an early stage of the disease. IRIS-inhibitory peptide killed these IRISOE TNBC/TICs, in vivo and prevented their dissemination and metastasis. We propose IRIS inactivation could be pursued to prevent dissemination and metastasis from early TNBC tumor lesions in patients.