Expression analysis of BORIS during pluripotent, differentiated, cancerous, and non-cancerous cell states

The function of brother of the regulator of imprinted sites in cancer development

As Douglas Hanahan and Robert Weinberg compiled, there are nine hallmarks of cancer that are conducive to cancer cell development and survival. Previous studies showed that brother of the regulator of imprinted sites (BORIS) might promote cancer progression through these aspects. The competition between BORIS and CCCTC-binding factor (CTCF), which is crucial in the formation of chromatin loops, affects the normal function of CTCF and leads to neoplasia and deformity. In addition, BORIS belongs to the cancer-testis antigen families, which are potential targets in cancer diagnosis and treatment. Herein, we discuss the function and mechanisms of BORIS, especially in cancer development.

Molecular Regulation of Androgen Receptors in Major Female Reproductive System Cancers

There are three main types of cancer in the female reproductive system, specifically ovarian cancer (OVCA), endometrial cancer (EC), and cervical cancer (CC). They are common malignant tumors in women worldwide, with high morbidity and mortality. In recent years, androgen receptors (ARs) have been found to be closely related to the occurrence, progression, prognosis, and drug resistance of these three types of tumors. This paper summarizes current views on the role of AR in female reproductive system cancer, the associations between female reproductive system cancers and AR expression and polymorphisms. AR regulates the downstream target genes transcriptional activity and the expression via interacting with coactivators/corepressors and upstream/downstream regulators and through the gene transcription mechanism of “classical A/AR signaling” or “non-classical AR signaling”, involving a large number of regulatory factors and signaling pathways. ARs take part in the processes of cancer cell proliferation, migration/invasion, cancer cell stemness, and chemotherapeutic drug resistance. These findings suggest that the AR and related regulators could target the treatment of female reproductive system cancer.

Phytol Down-Regulates Expression of Some Cancer Stem Cell Markers and Decreases Side Population Proportion in Human Embryonic Carcinoma NCCIT Cells

Cancer stem cells (CSCs), a subgroup of cancer cells, have self-renewal capacity and differentiation potential and drive tumor growth. CSCs are highly-resistant to conventional chemo-radio therapy. Phytochemicals were shown to be able to eliminate CSCs. Phytol is a diterpene alcohol with demonstrated anticancer effects. The current study compared the effect of phytol with retinoic acid (RA) as a well-known inducers of CSC differentiation and cisplatin, a common chemotherapy drug, on CSC markers in human embryonic carcinoma NCCIT cells. NCCIT cells were exposed to 10 mM RA for 14 day to induce differentiation. Moreover, NCCIT cells were treated with IC₅₀ dose of cisplatin (12 µM) and phytol (40 µM) for 7 day. Real-time PCR showed that phytol was more effective that RA and cisplatin in down-regulating the CSC markers OCT4, NANOG, SOX2, ALDH1, ABCB1, CD44 and CD133. Percentage of SP (13%) and ABCB1⁺ (0.34%) in NCCIT cells decreased to 7% and 0.1% respectively after treatment with phytol. A very small proportion of NCCIT cells were positive for CD44 (0.2%) and CD133 (0.48%) and this fraction did not change significantly after treatment with three agents. In conclusion, phytol has the greatest inhibitory effect on CSC population and markers than RA and cisplatin.

The epigenetic factor BORIS (CTCFL) controls the androgen receptor regulatory network in ovarian cancer

The identification of prognostic biomarkers is a priority for patients suffering from high-grade serous ovarian cancer (SOC), which accounts for >70% of ovarian cancer (OC) deaths. Meanwhile, borderline ovarian cancer (BOC) is a low malignancy tumor and usually patients undergo surgery with low probabilities of recurrence. However, SOC remains the most lethal neoplasm due to the lack of biomarkers for early diagnosis and prognosis. In this regard, BORIS (CTCFL), a CTCF paralog, is a promising cancer biomarker that is overexpressed and controls transcription in several cancer types, mainly in OC. Studies suggest that BORIS has an important function in OC by altering gene expression, but the effect and extent to which BORIS influences transcription in OC from a genome-wide perspective is unclear. Here, we sought to identify BORIS target genes in an OC cell line (OVCAR3) with potential biomarker use in OC tumor samples. To achieve this, we performed in vitro knockout and knockdown experiments of BORIS in OVCAR3 cell line followed by expression microarrays and bioinformatics network enrichment analysis to identify relevant BORIS target genes. In addition, ex vivo expression data analysis of 373 ovarian cancer patients were evaluated to identify the expression patterns of BORIS target genes. In vitro, we uncovered 130 differentially expressed genes and obtained the BORIS-associated regulatory network, in which the androgen receptor (AR) acts as a major transcription factor. Also, FN1, FAM129A, and CD97 genes, which are related to chemoresistance and metastases in OC, were identified. In SOC patients, we observed that malignancy is associated with high levels of BORIS expression while BOC patients show lower levels. Our study suggests that BORIS acts as a main regulator, and has the potential to be used as a prognostic biomarker and to yield novel drug targets among the genes BORIS controls in SOC patients.

BORIS: a key regulator of cancer stemness

BORIS (CTCFL) is a DNA binding protein which is involved in tumorigenesis. Although, there are different opinions on the level of gene expression and function of BORIS in normal and cancer tissues, the results of many studies have classified BORIS as a protein belonging to cancer/testis (CT) genes, which are identified as a group of genes that are expressed normally in testis, and abnormally in various types of cancers. In testis, BORIS induces the expression of some male germ cell/testis specific genes, and plays crucial roles during spermatogenesis and production of sperm. In tumorigenesis, the role of BORIS in the expression induction of some CT genes and oncogenes, as well as increasing proliferation/viability of cancer cells has been demonstrated in many researches. In addition to cancer cells, some believe that BORIS is also expressed in normal conditions and plays a universal function in cell division and regulation of genes. The following is a comprehensive review on contradictory views on the expression pattern and biological function of BORIS in normal, as well as cancer cells/tissues, and presents some evidence that support the expression of BORIS in cancer stem cells (CSCs) and advanced stage/poorer differentiation grade of cancers. Boris is involved in the regulation of CSC cellular and molecular features such as self-renewal, chemo-resistance, tumorigenicity, sphere-forming ability, and migration capacity. Finally, the role of BORIS in regulating two important signaling pathways including Wnt/β-catenin and Notch in CSCs, and its ability in recruiting transcription factors or chromatin-remodeling proteins to induce tumorigenesis is discussed.

Down-regulation of BORIS/CTCFL efficiently regulates cancer stemness and metastasis in MYCN amplified neuroblastoma cell line by modulating Wnt/β-catenin signaling pathway

BORIS/CTCFL is a vital nucleotide binding protein expressed during embryogenesis and gametogenesis. BORIS/CTCFL is the paralogue of transcriptional repressor protein CTCF, which is aberrantly expressed in various malignancies and primarily re-expressed in cancer stem cells (CSCs). The mechanism behind regulation of BORIS in various cancer conditions and tumor metastases is so far not explored in detail. The aim of the study was to understand the influence of BORIS/CTCFL on stemness and metastasis by regulating well-known oncogenes and related signaling pathways. In our study, we have identified a cross-talk between expression of BORIS/CTCFL and Wnt/β-catenin signaling pathway, which plays a crucial role in various processes including ontogenesis, embryogenesis and maintenance of stem cell properties. Upon knockdown of BORIS/CTCFL, we observed an upregulation of Mesenchymal to Epithelial transition markers such as E-cad and downregulation of Epithelial to Mesenchymal transition markers such as N-CAD, Vimentin, SNAIL, etc. This transition was accomplished by activation of Wnt/β-catenin signaling pathway by regulating upstream and downstream Wnt associated proteins including β-catenin, Wnt3a/5a, CD44, MYC etc. We also identified that BMI1, an oncogene belonging to polycomb group expressed positively with levels of BORIS/CTCFL. Our study implicates the role of BORIS/CTCFL in maintenance of stemness and in transition from mesenchymal to epithelial state in MYC amplified neuroblastoma IMR-32 cells. Effectively controlling BORIS/CTCFL levels can inhibit disease establishment and hence can be considered as a potent target for cancer therapy.