Peng‐Sheng Zheng

NF‐YA promotes the cell proliferation and tumorigenic properties by transcriptional activation of SOX2 in cervical cancer

AbstractNF‐YA is considered as a crucial regulator for the maintenance of cancer stem cell (CSC) and involved in various types of malignant tumours. However, the exact function and molecular mechanisms of NF‐YA in the progression of cervical cancer remains poorly understood. Here, the expression of NF‐YA detected by immunohistochemistry was gradually increased from normal cervical tissues, to the high‐grade squamous intraepithelial lesions, and then to cervical cancer tissues. NF‐YA promoted the cell proliferation and tumorigenic properties of cervical cancer cells as well as tumorsphere formation and chemoresistance in vitro. The luciferase reporter assay combined with mutagenesis analyses and Western blotting showed that NF‐YA trans‐activated the expression of SOX2 in cervical cancer. Furthermore, quantitative chromatin immunoprecipitation (qChIP) and electrophoretic mobility shift assay (EMSA) confirmed that NF‐YA protein directly bound to the CCAAT box region located upstream of the SOX2 promoter. Together, our data demonstrated that NF‐YA was highly expressed in cervical cancer and promoted the cell proliferation, tumorigenicity and CSC characteristic by trans‐activating the expression of SOX2.

PRDM4 inhibits cell proliferation and tumorigenesis by inactivating the PI3K/AKT signaling pathway through targeting of PTEN in cervical carcinoma

AbstractPR domain zinc finger protein 4 (PRDM4) is a transcription factor that plays key roles in stem cell self-renewal and tumorigenesis. However, its biological role and exact mechanism in cervical cancer remain unknown. Here, both immunohistochemistry (IHC) and Western blot assays demonstrated that the expression of PRDM4 in cervical cancer tissues was much lower than that in the normal cervix. A xenograft assay showed that PRDM4 overexpression in the cervical cancer cell lines SiHa and HeLa dramatically inhibited cell proliferation and tumorigenic potential in vivo. Conversely, the silencing of PRDM4 promoted cervical cancer cell proliferation and tumorigenic potential. Mechanistically, PRDM4 induced cell cycle arrest at the transition from G0/G1 phase to S phase by upregulating p27 and p21 expression and downregulating Cyclin D1 and CDK4 expression. Furthermore, the PI3K/AKT signaling pathway was inactivated in PRDM4-overexpressing cells, which decreased the levels of p-AKT and upregulated the expression of PTEN, an inhibitor of the PI3K/AKT signaling pathway, at both the transcriptional and translational levels. Dual-luciferase reporter assays and qChIP assays confirmed that PRDM4 transactivated the expression of PTEN by binding to two specific regions in thePTENpromoter. Furthermore, PTEN silencing or a PTEN inhibitor rescued the cell defects induced by PRDM4 overexpression. Therefore, our data suggest that PRDM4 inhibits cell proliferation and tumorigenesis by downregulating the activity of the PI3K/AKT signaling pathway by directly transactivating PTEN expression in cervical cancer.

HOXB4 inhibits the proliferation and tumorigenesis of cervical cancer cells by downregulating the activity of Wnt/β-catenin signaling pathway

AbstractHomeobox B4 (HOXB4), which belongs to the homeobox (HOX) family, possesses transcription factor activity and has a crucial role in stem cell self-renewal and tumorigenesis. However, its biological function and exact mechanism in cervical cancer remain unknown. Here, we found that HOXB4 was markedly downregulated in cervical cancer. We demonstrated that HOXB4 obviously suppressed cervical cancer cell proliferation and tumorigenic potential in nude mice. Additionally, HOXB4-induced cell cycle arrest at the transition from the G0/G1 phase to the S phase. Conversely, loss of HOXB4 promoted cervical cancer cell growth both in vitro and in vivo. Bioinformatics analyses and mechanistic studies revealed that HOXB4 inhibited the activity of the Wnt/β-catenin signaling pathway by direct transcriptional repression of β-catenin. Furthermore, β-catenin re-expression rescued HOXB4-induced cervical cancer cell defects. Taken together, these findings suggested that HOXB4 directly transcriptional repressed β-catenin and subsequently inactivated the Wnt/β-catenin signaling pathway, leading to significant inhibition of cervical cancer cell growth and tumor formation.

NEK2 inactivates the Hippo pathway to advance the proliferation of cervical cancer cells by cooperating with STRIPAK complexes

The never in mitosis gene A (NIMA)-related kinase 2 (NEK2) protein has been reported to be an oncoprotein that plays different oncogenic roles in multiple cancers. Here, we confirmed that NEK2 highly expressed in cervical cancer cells rather than in normal epithelial basal layer cells in cervical tissues and correlated with worse outcomes. We also demonstrated that NEK2 promoted the in vivo growth of subcutaneous xenograft tumors stemming from cervical cancer cells and the in vitro cell proliferation by decreasing Ser127-phosphorylation of the YAP protein retained in the cytoplasm while increasing the levels of active nucleus-associated YAP protein, which was followed by increases in the targeted proteins CTGF, CYR61 and GLI2. Furthermore, the Hippo signaling pathway was inactivated in manipulated NEK2-overexpressing cervical cancer cells by regulating the levels of MST1/2 dephosphorylation. Additionally, mass spectrometric sequencing and bilateral coimmunoprecipitation were employed suggested that NEK2 acted at an early upstream step to promote dephosphorylation of MST2 and inactivate the Hippo signaling cascade by cooperating with STRIPAK complexes. We conjecture that NEK2 may be a future target for cervical cancer therapy.

ESRRB Inhibits the TGFβ Signaling Pathway to Drive Cell Proliferation in Cervical Cancer

Abstract Estrogen-related receptor β (ESRRB) is a member of the orphan nuclear receptor family and mediates stem cell self-renewal and early embryonic development. Previous studies have also reported that ESRRB plays a role in the development and progression of breast cancer and prostate cancer. In this study, we observed that ESRRB was highly expressed in cervical cancer and was associated with disease progression. Knocking out ESRRB using CRISPR/Cas9 gene editing in cervical cancer cells induced cell-cycle arrest at the transition from the G0–G1 phase to the S phase, resulting in inhibition of cell proliferation in vitro and reduced tumor growth in vivo. Conversely, ectopic expression of ESRRB significantly promoted the proliferation of cervical cancer cells. ESRRB activated transcription of SMAD7, a TGFβ pathway inhibitor, which blocked phosphorylation and nuclear translocation of SMAD2/3 to the nucleus, thereby downregulating CDKN1A and upregulating CCNA2 and MYC. In turn, MYC transactivated ESRRB and upregulated SMAD7, thus forming a positive feedback loop with ESRRB. Together, these findings identify the tumor-promoting function of ESRRB in cervical cancer and reveal a mechanism by which ESRRB stimulates cell proliferation to promote cancer progression. Significance: The ESRRB/SMAD7/MYC-positive feedback loop inhibits TGFβ signaling to activate cell-cycle progression and promote proliferation in cervical cancer, thereby driving tumor growth.