TBP-like Protein (TLP) Disrupts the p53-MDM2 Interaction and Induces Long-lasting p53 Activation

The roles of ubiquitination in AML

Acute myeloid leukemia (AML) is a heterogeneously malignant disorder resulting in poor prognosis. Ubiquitination, a major post-translational modification (PTM), plays an essential role in regulating various cellular processes and determining cell fate. Despite these initial insights, the precise role of ubiquitination in AML pathogenesis and treatment remains largely unknown. In order to address this knowledge gap, we explore the relationship between ubiquitination and AML from the perspectives of signal transduction, cell differentiation, and cell cycle control; and try to find out how this relationship can be utilized to inform new therapeutic strategies for AML patients.

Identification of E3 ubiquitin ligase-associated prognostic genes and construction of a prediction model for uterine cervical cancer based on bioinformatics analysis

E3 ligases are engaged in a variety of physiological processes within cells and use ubiquitin-labeled substrates to control their activity and stability. Although some research has indicated that E3 ligases or particular substrates have an impact on the treatment that cervical cancer patients get after their diagnosis, The exact purpose of these enzymes in the occurrence and evolution of cancer of the cervical region (CC) is not clear. In order to extract and analyze relevant mRNA gene expression data as well as clinical patient data, we used open databases. A reliable risk prediction model was developed by applying the least absolute shrinkage and selection operator (LASSO) technique in conjunction with Cox regression analysis. Column-line plots were combined to analyze the predictive model, and the GSE44001 dataset served as an external validation.Four gene models:proteasome (prosome, macropain) 26S subunit, non-ATPase, 14(PSMD14),proteasome (prosome, macropain) subunit, alpha type, 4(PSMA4,),zinc finger and BTB domain containing 16(ZBTB16),and ankyrin repeat domain 9(ANKRD9). Gene expression levels in both healthy and cancerous tissues have been confirmed by the HPA database. Next, the investigation focused on immunological state and tumor mutation load. The high-risk group and Cluster B had distinct levels of immune cell infiltration and a worse prognosis. Additionally, KEGG and GO analyses of differentially expressed genes (DEGs) between the high- and low-risk groups were performed, as well as tumor microenvironment (TME) investigations. Targeting E3 ligases may be an efficient strategy to treat cervical cancer (CC), according to a novel and comprehensive E3 ubiquitination ligase-associated gene model that has been presented.

The E3 Ligases in Cervical Cancer and Endometrial Cancer

Endometrial (EC) and cervical (CC) cancers are the most prevalent malignancies of the female reproductive system. There is a global trend towards increasing incidence and mortality, with a decreasing age trend. E3 ligases label substrates with ubiquitin to regulate their activity and stability and are involved in various cellular functions. Studies have confirmed abnormal expression or mutations of E3 ligases in EC and CC, indicating their vital roles in the occurrence and progression of EC and CC. This paper provides an overview of the E3 ligases implicated in EC and CC and discusses their underlying mechanism. In addition, this review provides research advances in the target of ubiquitination processes in EC and CC.

Relationship among DNA double-strand break (DSB), DSB repair, and transcription prevents genome instability and cancer

DNA double‐strand break (DSB) is a serious type of DNA damage and is known to trigger multiple responses within cells. In these responses, novel relationships among DSB, DSB repair, and transcription machineries are created. First, transcription is repressed if DSB occurs near or at the transcription site, termed DSB‐induced transcriptional repression, which contributes to DSB repair with the aid of DNA damage‐signaling pathways, ATM‐ or DNA‐PKcs‐signaling pathways. DSB‐induced transcriptional repression is also regulated by transcriptional factors TLP1, NELF, and ENL, as well as chromatin remodeling and organizing factors ZMYND8, CDYL1, PBAF, and cohesin. Second, transcription and RNA promote DSB repair for genome integrity. Transcription factors such as LEDGF, SETD2, and transcriptionally active histone modification, H3K36, facilitate homologous recombination to overcome DSB. At transcriptional active sites, DNA:RNA hybrids, termed R‐loops, which are formed by DSB, are processed by RAD52 and XPG leading to an activation of the homologous recombination pathway. Even in a transcriptionally inactive non‐genic sites, noncoding RNAs that are produced by RNA polymerase II, DICER, and DROSHA, help to recruit DSB repair proteins at the DSB sites. Third, transcriptional activation itself, however, can induce DSB. Transcriptional activation often generates specific DNA structures such as R‐loops and topoisomerase‐induced DSBs, which cause genotoxic stress and may lead to genome instability and consequently to cancer. Thus, transcription and DSB repair machineries interact and cooperate to prevent genome instability and cancer.

Tumor-Suppressive MicroRNA-216b Binds to TPX2, Activating the p53 Signaling in Human Cutaneous Squamous Cell Carcinoma

Dysregulation of microRNAs (miRNAs) is acknowledged in human cutaneous squamous cell carcinoma (cSCC). We hereby evaluated the ability of miRNA-216b (miR-216b) to impact human cSCC. cSCC tissues with corresponding adjacent normal tissues were collected from 40 patients diagnosed with cSCC where the expression pattern of miR-216b and targeting protein for Xenopus kinesin-like protein 2 (TPX2) was determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot analysis. A431 cells were transfected with miR-216b mimic, miR-216b inhibitor, or short interfering RNA against TPX2 to evaluate cell proliferation, invasion, migration, and apoptosis using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, scratch test, Transwell assay, and flow cytometry. TPX2 was highly expressed in cSCC tissues while miR-216b was poorly expressed in association with tumor differentiation, lymph node metastasis, and tumor node metastasis staging in patients with cSCC. In response to overexpressed miR-216b or silenced TPX2, cSCC cell proliferation, invasion, and migration were suppressed and apoptosis was stimulated, along with activated p53 signaling. Thus, upregulated miR-216b was capable of promoting apoptosis and inhibiting proliferation, invasion, and migration of cSCC cells by downregulating TPX2 through activation of the p53 signaling, highlighting a novel biomarker for novel treatment modalities against cSCC.

TLP-mediated global transcriptional repression after double-strand DNA breaks slows down DNA repair and induces apoptosis

Transcription and DNA damage repair act in a coordinated manner. Recent studies have shown that double-strand DNA breaks (DSBs) are repaired in a transcription-coupled manner. Active transcription results in a faster recruitment of DSB repair factors and expedites DNA repair. On the other hand, transcription is repressed by DNA damage through multiple mechanisms. We previously reported that TLP, a TATA box-binding protein (TBP) family member that functions as a transcriptional regulator, is also involved in DNA damage-induced apoptosis. However, the mechanism by which TLP affects DNA damage response was largely unknown. Here we show that TLP-mediated global transcriptional repression after DSBs is crucial for apoptosis induction by DNA-damaging agents such as etoposide and doxorubicin. Compared to control cells, TLP-knockdown cells were resistant to etoposide-induced apoptosis and exhibited an elevated level of global transcription after etoposide exposure. DSBs were efficiently removed in transcriptionally hyperactive TLP-knockdown cells. However, forced transcriptional shutdown using transcriptional inhibitors α-amanitin and 5,6-dichloro-1-ß-D-ribofuranosylbenzimidazole (DRB) slowed down DSB repair and resensitized TLP-knockdown cells to etoposide. Taken together, these results indicate that TLP is a critical determinant as to how cells respond to DSBs and triggers apoptosis to cells that have sustained DNA damage.

RECK inhibits cervical cancer cell migration and invasion by promoting p53 signaling pathway

The present study was conducted to investigate the effects of RECK on cervical cancer cell migration and invasion to help understand relevant molecular mechanisms. QRT-PCR and western blot were respectively utilized to examine the transcriptional and translational levels of RECK in cervical cancer cell lines (HELA and C33A) and normal cell line (H8). After transfection with RECK overexpressing vectors, the expression of RECK mRNA, RECK and p53 signaling pathway-related proteins (p21, p53, bcl-2, and Bax) in cervical cancer cells were respectively examined using qRT-PCR and western blot. Cervical cancer cell migration after transfection was detected by wound healing assay and transwell assay. RECK expression was much lower in cervical cancer cell lines compared with normal cell line. Results of wound-healing assay results indicated that RECK could inhibit cervical cancer cell migration, and transwell assay results demonstrated that cell invasion was suppressed by RECK overexpression. Furthermore, western blot indicated that the overexpression of RECK could promote the activation of p53 signaling pathway by influencing related protein expression; whereas its inhibition by PFT-α could antagonize the effect of RECK on migrative and invasive abilities of cervical cancer cells. RECK could inhibit the migration and invasion of cervical cancer cells by activating p53 signaling pathway.