The function of SOX2 in breast cancer and relevant signaling pathway

The combination therapy using tyrosine kinase receptors inhibitors and repurposed drugs to target patient-derived glioblastoma stem cells

The lesson from many studies investigating the efficacy of targeted therapy in glioblastoma (GBM) showed that a future perspective should be focused on combining multiple target treatments. Our research aimed to assess the efficacy of drug combinations against glioblastoma stem cells (GSCs). Patient-derived cells U3042, U3009, and U3039 were obtained from the Human Glioblastoma Cell Culture resource. Additionally, the study was conducted on a GBM commercial U251 cell line. Gene expression analysis related to receptor tyrosine kinases (RTKs), stem cell markers and genes associated with significant molecular targets was performed, and selected proteins encoded by these genes were assessed using the immunofluorescence and flow cytometry methods. The cytotoxicity studies were preceded by analyzing the expression of specific proteins that serve as targets for selected drugs. The cytotoxicity study using the MTS assay was conducted to evaluate the effects of selected drugs/candidates in monotherapy and combinations. The most cytotoxic compounds for U3042 cells were Disulfiram combined with Copper gluconate (DSF/Cu), Dacomitinib, and Foretinib with IC50 values of 52.37 nM, 4.38 µM, and 4.54 µM after 24 h incubation, respectively. Interactions were assessed using SynergyFinder Plus software. The analysis enabled the identification of the most effective drug combinations against patient-derived GSCs. Our findings indicate that the most promising drug combinations are Dacomitinib and Foretinib, Dacomitinib and DSF/Cu, and Foretinib and AZD3759. Since most tested combinations have not been previously examined against glioblastoma stem-like cells, these results can shed new light on designing the therapeutic approach to target the GSC population.

Epigenetic reprogramming of a distal developmental enhancer cluster drives SOX2 overexpression in breast and lung adenocarcinoma

Enhancer reprogramming has been proposed as a key source of transcriptional dysregulation during tumorigenesis, but the molecular mechanisms underlying this process remain unclear. Here, we identify an enhancer cluster required for normal development that is aberrantly activated in breast and lung adenocarcinoma. Deletion of the SRR124-134 cluster disrupts expression of the SOX2 oncogene, dysregulates genome-wide transcription and chromatin accessibility and reduces the ability of cancer cells to form colonies in vitro. Analysis of primary tumors reveals a correlation between chromatin accessibility at this cluster and SOX2 overexpression in breast and lung cancer patients. We demonstrate that FOXA1 is an activator and NFIB is a repressor of SRR124-134 activity and SOX2 transcription in cancer cells, revealing a co-opting of the regulatory mechanisms involved in early development. Notably, we show that the conserved SRR124 and SRR134 regions are essential during mouse development, where homozygous deletion results in the lethal failure of esophageal-tracheal separation. These findings provide insights into how developmental enhancers can be reprogrammed during tumorigenesis and underscore the importance of understanding enhancer dynamics during development and disease.

Pleiotropic effects of DCLK1 in cancer and cancer stem cells

Doublecortin-like kinase 1 (DCLK1), a protein molecule, has been identified as a tumor stem cell marker in the cancer cells of gastrointestinal, pancreas, and human colon. DCLK1 expression in cancers, such as breast carcinoma, lung carcinoma, hepatic cell carcinoma, tuft cells, and human cholangiocarcinoma, has shown a way to target the DCLK1 gene and downregulate its expression. Several studies have discussed the inhibition of tumor cell proliferation along with neoplastic cell arrest when the DCLK1 gene, which is expressed in both cancer and normal cells, was targeted successfully. In addition, previous studies have shown that DCLK1 plays a vital role in various cancer metastases. The correlation of DCLK1 with numerous stem cell receptors, signaling pathways, and genes suggests its direct or an indirect role in promoting tumorigenesis. Moreover, the impact of DCLK1 was found to be related to the functioning of an oncogene. The downregulation of DCLK1 expression by using targeted strategies, such as embracing the use of siRNA, miRNA, CRISPR/Cas9 technology, nanomolecules, specific monoclonal antibodies, and silencing the pathways regulated by DCLK1, has shown promising results in both in vitro and in vivo studies on gastrointestinal (GI) cancers. In this review, we will discuss about the present understanding of DCLK1 and its role in the progression of GI cancer and metastasis.

Understanding the function and regulation of Sox2 for its therapeutic potential in breast cancer

Sox family of transcriptional factors play essential functions in development and are implicated in multiple clinical disorders, including cancer. Sox2 being their most prominent member and performing a critical role in reprogramming differentiated adult cells to an embryonic phenotype is frequently upregulated in multiple cancers. High Sox2 levels are detected in breast tumor tissues and correlate with a worse prognosis. In addition, Sox2 expression is connected with resistance to conventional anticancer therapy. Together, it can be said that inhibiting Sox2 expression can reduce the malignant features associated with breast cancer, including invasion, migration, proliferation, stemness, and chemoresistance. This review highlights the critical roles played by the Sox gene family members in initiating or suppressing breast tumor development, while primarily focusing on Sox2 and its role in breast tumor initiation, maintenance, and progression, elucidates the probable mechanisms that control its activity, and puts forward potential therapeutic strategies to inhibit its expression.

Expression and significance of SOX B1 genes in glioblastoma multiforme patients

The overall survival of glioblastoma multiforme (GBM) patients remains poor. To improve patient outcomes, effective diagnostic and prognostic biomarkers for GBM are needed. In this study, we first applied bioinformatic analyses to identify biomarkers for GBM, focusing on SOX (sex‐determining region on the Y chromosome (SRY)‐related high mobility group (HMG) box) B1 family members. The ONCOMINE, GEPIA, LinkedOmics and CCLE databases were used to assess mRNA expression levels of the SOX B1 family members in different cancers and normal tissue. Further bioinformatic analysis was performed using the ONCOMINE database in combination with the LinkedOmics data set to identify the prognostic value of SOX B1 family members for GBM. We found mRNA expression levels of all tested SOX B1 genes were significantly increased in GBM. In the LinkedOmics database, increased expression of SOX3 indicated a better overall survival. In GEPIA databases, increased expression of all SOX B1 family members suggested an improved overall survival, but none of them were statistically different. Then, Transwell assays and wound healing were employed to evaluate the motility and invasive captivity of U251 cells when silencing SOX2 and SOX3. We found exogenous inhibition of SOX2 appeared to reduce the migration and invasion of U251 cells in vitro. Collectively, our research suggested that SOX2 might serve as a cancer‐promoting gene to identify high‐risk GBM patients, and SOX3 had the potential to be a prognostic biomarker for GBM patients.

Cervical cancer progression is regulated by SOX transcription factors: Revealing signaling networks and therapeutic strategies

Cervical cancer is the fourth common gynecologic cancer and is considered as second leading cause of death among women. Various strategies are applied in treatment of cervical cancer including radiotherapy, chemotherapy and surgery. However, cervical cancer cells demonstrate aggressive behavior in advanced phases, requiring novel strategies in their elimination. On the other hand, SOX proteins are transcription factors capable of regulating different molecular pathways and their expression varies during embryogenesis, disease development and carcinogenesis. In the present review, our aim is to reveal role of SOX transcription factors in cervical cancer. SOX transcription factors play like a double-edged sword in cancer. For instance, SOX9 possesses both tumor-suppressor and tumor-promoting role in cervical cancer. Therefore, exact role of each SOX members in cervical cancer has been discussed to direct further experiments for revealing other functions. SOX proteins can regulate proliferation and metastasis of cervical cancer cells. Furthermore, response of cervical cancer cells to chemotherapy and radiotherapy is tightly regulated by SOX transcription factors. Different downstream targets of SOX proteins such as Wnt signaling, EMT and Hedgehog have been identified. Besides, upstream mediators such as microRNAs, lncRNAs and circRNAs can regulate SOX expression in cervical cancer. In addition to pre-clinical studies, role of SOX transcription factors as prognostic and diagnostic tools in cervical cancer has been shown.

Long non-coding RNA PROX1-AS1 knockdown upregulates microRNA-519d-3p to promote chemosensitivity of retinoblastoma cells via targeting SOX2

OBJECTIVE

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) participate in tumor progression, while the role of PROX1-antisense RNA1 (PROX1-AS1) sponging miR-519d-3p in retinoblastoma (RB) remains largely unknown. We aim to explore the effect of the PROX1-AS1/miR-519d-3p/sex determining region Y-box 2 (SOX2) in chemosensitivity of RB cells.

METHODS

Expression of PROX1-AS1, miR-519d-3p and SOX2 in RB tissues and cells was determined. The drug-resistant cell lines were established and respectively intervened with PROX1-AS1 or miR-519d-3p expression to explore their roles in drug resistance and malignant behaviors of the drug-resistant cells. The binding relationships between PROX1-AS1 and miR-519d-3p, and between miR-519d-3p and SOX2 were evaluated.

RESULTS

PROX1-AS1 and SOX2 were upregulated while miR-519d-3p was downregulated in RB tissues and cells, especially in drug-resistant cells. The PROX1-AS1 inhibition or miR-519d-3p elevation suppressed the drug resistance, proliferation, migration and invasion, and promoted apoptosis of the drug-resistant RB cells. Moreover, PROX1-AS1 sponged miR-519d-3p and miR-519d-3p targeted SOX2.

CONCLUSION

PROX1-AS1 knockdown upregulates miR-519d-3p to promote chemosensitivity of RB cells via targeting SOX2.

LncRNA RP11-499E18.1 Inhibits Proliferation, Migration, and Epithelial-Mesenchymal Transition Process of Ovarian Cancer Cells by Dissociating PAK2-SOX2 Interaction

Background: Ovarian cancer (OC)is a deadly gynecological malignancy worldwide. It is urgent to identify diagnostic biomarkers of OC to disclose the underlying mechanism. Methods and Materials: Bioinformatics analysis was used to identify target genes. Gene expression was detected and altered by qRT-PCR and cell transfection, respectively. The interaction between RP11-499E18.1 and PAK2, as well as that between PAK2 and SOX2, was determined using RNA pulldown, RNA immunoprecipitation (RIP), and co-immunoprecipitation (co-IP) assay, respectively. Localizations of RP11-499E18.1, PAK2, and SOX2 were respectively determined employing immunohistochemical (IHC), IF, and FISH. The regulatory effects of RP11-499E18.1, PAK2, and SOX2 on OC cell proliferation, migration, colony formation, epithelial-mesenchymal transition (EMT)-related factor expression, and SOX2 nuclear translocation were determined. Finally, the effects of RP11-499E18.1 and PAK2 expression on the tumor growth in nude mice were determined. Results: RP11-499E18.1, PAK2, and SOX2 were selected in our study. RP11-499E18.1 was downregulated, while PAK2 and SOX2 was upregulated in OC tissues and cells. RP11-499E18.1 coexists in the nucleus and cytoplasm of OC cells. There is an interaction between RP11-499E18.1 and PAK2, as well as PAK2 and SOX2 in OC cells. Alteration of RP11-499E18.1 and PAK2 expression both had no influence on PAK2 and SOX2 levels, but PAK2 upregulation notably augmented p-SOX2 level. RP11-499E18.1 overexpression suppressed OC cell proliferation, migration, and colony formation, as well as SOX2 nuclear translocation. Besides, it inhibited tumor growth in nude mice. However, these effects were notably reversed by PAK2 upregulation and eventually offset by SOX2 knockdown. Additionally, RP11-499E18.1 overexpression reduced PAK2-SOX2 interaction and SOX phosphorylation, and increased the binding of RP11-499E18.1 by PAK2. Conclusion: These lines of evidence demonstrated that RP11-499E18.1 might play its tumor suppressor roles in OC via regulation of the RP11-499E18.1-PAK2-SOX2 axis. This research indicated that RP11-499E18.1 might be used as a diagnostic biomarker for OC in the future.

Tumor-targeted delivery of siRNA to silence Sox2 gene expression enhances therapeutic response in hepatocellular carcinoma

RNA interference (RNAi) is one of the most promising methods for the treatment of malignant tumors. However, developing an efficient biocompatible delivery vector for small interfering RNA (siRNA) remains a challenging issue. This study aimed to prepare a non-viral tumor-targeted carrier, named RGDfC-modified functionalized selenium nanoparticles (RGDfC-SeNPs). RGDfC-SeNPs were used to selectively deliver siSox2 to HepG2 liver cancer cells and tissues for the treatment of hepatocellular carcinoma (HCC). In the current study, RGDfC-SeNPs were successfully synthesized and characterized. It was shown that RGDfC-SeNPs could effectively load siSox2 to prepare an antitumor prodrug RGDfC-Se@siSox2. RGDfC-Se@siSox2 exhibited selective uptake in HepG2 liver cancer cells and LO2 normal liver cells, indicating RGDfC-SeNPs could effectively deliver siSox2 to HepG2 liver cancer cells. RGDfC-Se@siSox2 entered HepG2 cells via clathrin-mediated endocytosis by firstly encircling the cytoplasm and then releasing siSox2 in the lysosomes. RGDfC-Se@siSox2 could effectively silence Sox2 and inhibit the proliferation, migration and invasion of HepG2 cells. RGDfC-Se@siSox2 induced HepG2 cells apoptosis most likely via overproduction of reactive oxygen species and disruption of the mitochondrial membrane potentials. Most importantly, RGDfC-Se@siSox2 significantly inhibited the tumor growth in HepG2 tumor-bearing mice without obvious toxic side effects. These studies indicated that RGDfC-SeNPs may be an ideal gene carrier for delivering siSox2 to HepG2 cells and that RGDfC-Se@siSox2 may be a novel and highly specific gene-targeted prodrug therapy for HCC.

Breast Cancer Cell Cultures on Electrospun Poly(ε-Caprolactone) as a Potential Tool for Preclinical Studies on Anticancer Treatments

During anticancer drug development, most compounds selected by in vitro screening are ineffective in in vivo studies and clinical trials due to the unreliability of two-dimensional (2D) in vitro cultures that are unable to mimic the cancer microenvironment. Herein, HCC1954 cell cultures on electrospun polycaprolactone (PCL) were characterized by morphological analysis, cell viability assays, histochemical staining, immunofluorescence, and RT-PCR. Our data showed that electrospun PCL allows the in vitro formation of cultures characterized by mucopolysaccharide production and increased cancer stem cell population. Moreover, PCL-based cultures were less sensitive to doxorubicin and electroporation/bleomycin than those grown on polystyrene plates. Collectively, our data indicate that PCL-based cultures may be promising tools for preclinical studies.