E2F1 activates p53 transcription through its distal site and participates in apoptosis induction in HPV-positive cells

Troponin C-1 Activated by E2F1 Accelerates Gastric Cancer Progression via Regulating TGF-β/Smad Signaling

BACKGROUND

Troponin C-1 (TNNC1) has been previously characterized as an oncogenic gene.

AIMS

This study aimed to reveal the roles of TNNC1 in gastric cancer and the potential underlying mechanisms.

METHODS

TNNC1 siRNAs and TNNC1 overexpression plasmid were used to alter its expression in AGS, MKN45, and HGC-27 cells. CCK-8 assay, colony formation, EdU assay, flow cytometry, transwell assay, and scratch test were conducted to measure the phenotype changes. In vivo effects of TNNC1 silence were confirmed by using a xenograft mouse model. Bioinformatics analysis was conducted to screen out the transcription factor and downstream signaling of TNNC1.

RESULTS

TNNC1 was highly expressed in gastric cancer tissues and cell lines, and its expression was associated with poor prognosis. TNNC1 silence suppressed the proliferation, migration, and invasion of AGS and MKN45 cells. However, TNNC1 silence induced apoptosis by mediating the cleavage of caspase-3 and caspase-9. Overexpression of TNNC1 in HGC-27 cells led to the contrary effects. The anti-tumor effects of TNNC1 silence were also confirmed in a xenograft animal model. E2F1 was validated as an upstream transcription factor of TNNC1. Effects of TNNC1 silence on AGS cell migration and invasion were attenuated by E2F1 overexpression. Besides, TGF-β/Smad was a downstream signaling pathway of TNNC1. The anti-tumor impacts of TNNC1 silence were weaken by SB431542 (a specific inhibitor of TGF-β signaling) while accelerated by TGF-β.

CONCLUSION

TNNC1 activated by E2F1 functioned as an oncogenic gene through regulating TGF-β/Smad signaling. TNNC1 was suggested as a potential molecular drug target of gastric cancer.

Biosynthesis, total synthesis, and pharmacological activities of aryltetralin-type lignan podophyllotoxin and its derivatives

Covering: up to 2022Podophyllotoxin (PTOX, 1), a kind of aryltetralin-type lignan, was first discovered in the plant Podophyllum peltatum and its structure was clarified by W. Borsche and J. Niemann in 1932. Due to its potent anti-cancer and anti-viral activities, it is considered one of the molecules most likely to be developed into modern drugs. With the increasing market demand and insufficient storage of natural resources, it is crucial to expand the sources of PTOXs. The original extraction method from plants has gradually failed to meet the requirements, and the biosynthesis and total synthesis have become the forward-looking alternatives. As key enzymes in the biosynthetic pathway of PTOXs and their catalytic mechanisms being constantly revealed, it is possible to realize the heterogeneous biosynthesis of PTOXs in the future. Chemical and chemoenzymatic synthesis also provide schemes for strictly controlling the asymmetric configuration of the tetracyclic core. Currently, the pharmacological activities of some PTOX derivatives have been extensively studied, laying the foundation for clinical candidate drugs. This review focuses primarily on the latest research progress in the biosynthesis, total synthesis, and pharmacological activities of PTOX and its derivatives, providing a more comprehensive understanding of these widely used compounds and supporting the future search for clinical applications.

A3 Adenosine and P2X7 Purinergic Receptors as New Targets for an Innovative Pharmacological Therapy of Malignant Pleural Mesothelioma

Human malignant pleural mesothelioma (MPM) is a rare, but aggressive tumor of the serosal cavities whose 5-year survival rate is 15%. At present, there are no effective therapies for MPM. Although recent findings suggest that A3 adenosine (A3AR) and P2X7 (P2X7R) receptors can be employed as antitumoral pharmacological targets in MPM, their potential role in a combined therapy is currently unknown. The A3AR agonist Cl-IB-MECA and the P2X7 receptor antagonist AZ10606120, as a single compound or in combination, were investigated in vitro for their anti-tumor activities. Assays were carried out in MPM cell lines IST-Mes2 and MPP89 and in primary human normal mesothelial cells (HMCs), as control. Single treatment with Cl-IB-MECA reduced cell proliferation and favored a pro-apoptotic effect in both MPP89 and IST-Mes2 cell lines, whereas AZ10606120 inhibited cell proliferation and induced apoptosis in IST-Mes2, only. The combined treatment with Cl-IB-MECA and AZ10606120 reduced cell proliferation and favored apoptosis in MPP89 and IST-Mes2 cell lines, whereas no synergistic effect was detected. These data cumulatively suggest the absence of a synergistic effect in combined targeting of A3 adenosine and P2X7 receptors of MPM cell lines. This study may stimulate further investigations aimed at determining new combinations of antitumor compounds and more effective therapeutic strategies against MPM.

Receptor-Interacting Protein 140 Enhanced Temozolomide-Induced Cellular Apoptosis Through Regulation of E2F1 in Human Glioma Cell Lines

Glioblastoma (GBM), a grade IV glioma, is responsible for the highest years of potential life lost among cancers. The poor prognosis is attributable to its high recurrence rate, caused in part by the development of resistance to chemotherapy. Receptor-interacting protein 140 (RIP140) is a very versatile coregulator of nuclear receptors and transcription factors. Although many of the pathways regulated by RIP140 contribute significantly to cancer progression, the function of RIP140 in GBM remains to be determined. In this study, we found that higher RIP140 expression was associated with prolonged survival in patients with newly diagnosed GBM. Intracellular RIP140 levels were increased after E2F1 activation following temozolomide (TMZ) treatment, which in turn modulated the expression of E2F1-targeted apoptosis-related genes. Overexpression of RIP140 reduced glioma cell proliferation and migration, induced cellular apoptosis, and sensitized GBM cells to TMZ. Conversely, knockdown of RIP140 increased TMZ resistance. Taken together, our results suggest that RIP140 prolongs the survival of patients with GBM both by inhibiting tumor cell proliferation and migration and by increasing cellular sensitivity to chemotherapy. This study helps improve our understanding of glioma recurrence and may facilitate the development of more effective treatments.

Live cell, image-based high-throughput screen to quantitate p53 stabilization and viability in human papillomavirus positive cancer cells

Approximately 5% of cancers are caused by high-risk human papillomaviruses. Although very effective preventive vaccines will reduce this cancer burden significantly over the next several decades, they have no therapeutic effect for those already infected and remaining at risk for malignant progression of hrHPV lesions. HPV-associated cancers are dependent upon the expression of the viral E6 and E7 oncogenes. The oncogenic function of hrHPV E6 relies partially on its ability to induce p53 degradation. Since p53 is generally wildtype in hrHPV-associated cancers, p53 stabilization arrests proliferation, induces apoptosis and/or results in senescence. Here we describe a live cell, image-based high-throughput screen to identify compounds that stabilize p53 and/or affect viability in HPV-positive cancer HeLa cells. We validate the robustness and potential of this screening assay by assessing the activities of approximately 6,500 known bioactive compounds, illustrating its capability to function as a platform to identify novel therapeutics for hrHPV.

Therapeutic Effects of (5R)-5-Hydroxytriptolide on Fibroblast-Like Synoviocytes in Rheumatoid Arthritis via lncRNA WAKMAR2/miR-4478/E2F1/p53 Axis

Rheumatoid arthritis (RA) is an autoimmune disease. Fibroblast-like synoviocytes (FLS) serve a major role in synovial hyperplasia and inflammation in RA. (5R)-5-hydroxytriptolide (LLDT-8), a novel triptolide derivative, shows promising therapeutic effects for RA and is now in phase II clinical trials in China. However, the underlying mechanism of LLDT-8 is still not fully understood. Here, we found that LLDT-8 inhibited proliferation and invasion of RA FLS, as well as the production of cytokines. Microarray data demonstrated that LLDT-8 upregulated the expression of long non-coding RNA (lncRNA) WAKMAR2, which was negatively associated with proliferation and invasion of RA FLS, as well as the production of pro-inflammatory cytokines. Knockdown of WAKMAR2 abolished the inhibitory effects of LLDT-8 on RA FLS. Mechanistically, WAKMAR2 sponged miR-4478, which targeted E2F1 and downstreamed p53 signaling. Rescue experiments indicated that the inhibitory effects of LLDT-8 on RA FLS were dependent on WAKMAR2/miR-4478/E2F1/p53 axis.

Api5 a new cofactor of estrogen receptor alpha involved in breast cancer outcome

Api5 (Apoptosis inhibitor 5) is an anti-apoptotic factor that confers resistance to genotoxic stress in human cancer. Api5 is also expressed in endothelial cells and participates to the Estrogen Receptor α (ERα) signaling to promote cell migration. In this study, we found an over expression of Api5 in human breast cancer. Given that we show that high expression of Api5 in breast cancer patients is associated with shorter recurrence free survival, we investigated the relationship between ERα and Api5 at the molecular level. We found that Api5 Nuclear Receptor box (NR box) drives a direct interaction with the C domain of ERα. Furthermore, Api5 participates to gene transcription activation of ERα target genes upon estrogen treatment. Besides, Api5 expression favors tumorigenicity and migration and is necessary for tumor growth in vivo in mice xenografted model of breast cancer cell line. These finding suggest that Api5 is a new cofactor of ERα that functionally participates to the tumorigenic phenotype of breast cancer cells. In ERα breast cancer patients, Api5 overexpression is associated with poor survival, and may be used as a predictive marker of breast cancer recurrence free survival.

Systematic analysis of time-series gene expression data on tumor cell-selective apoptotic responses to HDAC inhibitors

SAHA (suberoylanilide hydroxamic acid or vorinostat) is the first nonselective histone deacetylase (HDAC) inhibitor approved by the US Food and Drug Administration (FDA). SAHA affects histone acetylation in chromatin and a variety of nonhistone substrates, thus influencing many cellular processes. In particularly, SAHA induces selective apoptosis of tumor cells, although the mechanism is not well understood. A series of microarray experiments was recently conducted to investigate tumor cell-selective proapoptotic transcriptional responses induced by SAHA. Based on that gene expression time series, we propose a novel framework for detailed analysis of the mechanism of tumor cell apoptosis selectively induced by SAHA. Our analyses indicated that SAHA selectively disrupted the DNA damage response, cell cycle, p53 expression, and mitochondrial integrity of tumor samples to induce selective tumor cell apoptosis. Our results suggest a possible regulation network. Our research extends the existing research.

Interaction of translationally controlled tumor protein with Apaf-1 is involved in the development of chemoresistance in HeLa cells

Background

Translationally controlled tumor protein (TCTP), alternatively called fortilin, is believed to be involved in the development of the chemoresistance of tumor cells against anticancer drugs such as etoposide, taxol, and oxaliplatin, the underlying mechanisms of which still remain elusive.

Methods

Cell death analysis of TCTP-overexpressing HeLa cells was performed following etoposide treatment to assess the mitochondria-dependent apoptosis. Apoptotic pathway was analyzed through measuring the cleavage of epidermal growth factor receptor (EGFR) and phospholipase C-γ (PLC-γ), caspase activation, mitochondrial membrane perturbation, and cytochrome c release by flow cytometry and western blotting. To clarify the role of TCTP in the inhibition of apoptosome, in vitro apoptosome reconstitution and immunoprecipitation was used. Pull-down assay and silver staining using the variants of Apaf-1 protein was applied to identify the domain that is responsible for its interaction with TCTP.

Results

In the present study, we confirmed that adenoviral overexpression of TCTP protects HeLa cells from cell death induced by cytotoxic drugs such as taxol and etoposide. TCTP antagonized the mitochondria-dependent apoptotic pathway following etoposide treatment, including mitochondrial membrane damage and resultant cytochrome c release, activation of caspase-9, and -3, and eventually, the cleavage of EGFR and PLC-γ. More importantly, TCTP interacts with the caspase recruitment domain (CARD) of Apaf-1 and is incorporated into the heptameric Apaf-1 complex, and that C-terminal cleaved TCTP specifically associates with Apaf-1 of apoptosome in apoptosome-forming condition thereby inhibiting the amplification of caspase cascade.

Conclusions

TCTP protects the cancer cells from etoposide-induced cell death by inhibiting the mitochondria-mediated apoptotic pathway. Interaction of TCTP with Apaf-1 in apoptosome is involved in the molecular mechanism of TCTP-induced chemoresistance. These findings suggest that TCTP may serve as a therapeutic target for chemoresistance in cancer treatment.

MicroRNA and gene networks in human Hodgkin's lymphoma

There has been significant progress in gene and microRNA (miRNA) research with regard to the morbidity of Hodgkin's lymphoma (HL). However, the regulatory mechanisms of genes and miRNAs have yet to be determined. In the current study, the regulatory association between genes, miRNAs and transcription factors (TFs) was investigated to gain an understanding of the mechanisms and key pathways of HL. The association between TFs and miRNAs, miRNAs and target genes and miRNA and its host gene was examined. To show the regulatory correlation clearly, three regulatory networks were hierarchically constructed: Differentially expressed, associated and global networks. Following comparison and analysis of the similarities and differences among the three networks, a number of key pathways, which showed self-adaptation associations were identified. This included NFκB1 and hsa-miR-9, hsa-miR-196a-1 and its host gene HOXB7, which separately forms a self-adaptation association. The differentially expressed network illuminated the pathogenesis of HL. In addition, the associated network further described the regulatory mechanism associated with HL, including prevention, diagnosis, development and therapy. The current study systematically explains the regulatory mechanisms of HL and supplies comprehensive data associated with HL for further studies. With increasing knowledge of the occurrence, mechanism, improvement, metastasis and treatment, an increased understanding of HL may be achieved.