Oncogenic nature of a novel mutant AATF and its interactome existing within human cancer cells

The Oncogenic and Immunological Roles of Apoptosis Antagonistic Transcription Factors in Human Tumors: A Pan-Cancer Analysis

Background

Apoptosis-antagonizing transcription factor (AATF) participates in tumor progression in multiple cancer types. However, its role across cancers is not well understood.

Methods

Data from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), Clinical Proteomic Tumor Analysis Consortium (CPTAC), and Human Protein Atlas (HPA) were used to analyze the multiomic roles of AATF in 33 tumor types, including gene and protein expression, survival prognosis, gene mutation, DNA methylation, protein phosphorylation, AATF coexpressed genes and their enrichment analysis, and immunological analysis.

Results

In TCGA and GTEx databases, 31 tumors and their corresponding normal tissues had AATF expression data, and it was differentially expressed in 29 of them. AATF was elevated in 27 tumors, decreased in 2 tumors, and was a risk factor for overall survival (OS) in 8 tumors and a risk factor for disease-free survival (DFS) in 4 tumors. AATF expression levels in various cancer types were significantly correlated with the infiltration levels of cancer-associated fibroblasts, endothelial cells, CD4+ T cells, B cells, myeloid dendritic cells, eosinophils, and macrophages. The immune checkpoints PD-1, PD-L1, and CTLA4 were positively correlated with AATF expression in bladder urothelial carcinoma (BLCA), kidney chromophobe (KICH), and prostate adenocarcinoma (PRAD).

Conclusion

In cancer, AATF expression is generally higher than that in normal tissue, and it is also associated with immunomodulation-related genes. AATF may be a risk factor for poor prognosis across cancers.

Futuristic approach to cancer treatment

Cancer is becoming one of the deadliest disease in both developed as well as developing countries and continuous effort is being made to find innovative therapies for myriad types of cancers that afflict the human body. Therapeutic options for cancer have grown exponentially over the time but we are quite a way off from finding a magic bullet that can help cure cancer and based on the current evidence we may never find a catch all cure ever and it becomes crucial that we keep on innovating and find multiple ways to attack the menace of this dreaded disease. Many patients suffer recurrence of disease and require second-line or in some cases more than two lines of treatment. In this review article we have discussed the available therapies along with the newer advancements that have been made in cancer therapy. Latest developments in treatment of various cancers that have been discussed include gene editing using CRISPR/Cas9, theranostics, viral mediated therapy, artificial intelligence, tumor infiltrating lymphocyte therapy, etc.

Autophagic dysfunction of β cell dysfunction in type 2 diabetes, a double-edged sword

Diabetes is an age-related disease, most of which is type 2 diabetes, and islet β cell dysfunction and insulin resistance are the main mechanisms of type 2 diabetes. Recent studies have revealed that autophagy plays an important role in maintaining the structure and function of islet beta cells and inhibiting insulin resistance and apoptosis induced by oxidative stress. In this review, we discussed the positive and negative effects of autophagy and its dysfunction on type 2 diabetes mellitus, which is the so-called double-edged sword, analysed its possible mechanism, and identified possible research hot spots.

Emerging roles of AATF: Checkpoint signaling and beyond

Apoptosis antagonizing transcription factor (AATF), an interacting partner of RNA polymerase II is a multifunctional protein that is highly conserved in eukaryotes. In addition to the regulation of gene expression as a transcriptional coactivator, AATF is shown to play a dual role in regulating the cell cycle by displacing histone deacetylases 1 (HDAC1) from the retinoblastoma-E2F transcription factor (Rb-E2F) complex and also from the specificity protein 1 (Sp1) transcription factor responsible for p21 expression, thereby ensuring cell proliferation and growth arrest, respectively, at different checkpoints of the cell cycle. Notably, AATF has emerged as one of the most important modulators of various cellular responses such as proliferation, apoptosis, and survival. Studies have demonstrated that AATF protects cells from multiple stress stimuli such as DNA damage, ER stress, hypoxia, or glucose deprivation by inducing cell cycle arrest, autophagy, or apoptosis inhibition. Furthermore, AATF serves as a critical regulator in various cancers and promotes tumorigenesis by protecting cancer cells from apoptosis induction, favoring cell proliferation, or promoting cell survival by autophagy. Recent studies have demonstrated the key role of AATF in ribosome biosynthesis and have also provided insights into the mechanistic role of AATF, offering impressive cytoprotection in myocardial infarction, neurologic diseases, and nephronophthisis. In this review, we will provide a comprehensive overview of the role of AATF and shed light on its emerging roles underlining the potential use of AATF as a novel biomarker and as an effective therapeutic target.

Tumorigenic PVT-1 gene locus is governed by miR-2909 RNomics

Genomic regulation and functional significance of PVT-1 gene locus, in the MYC-driven cancers, has remained enigmatic ever since its discovery. With the present study, an attempt is made to establish that cellular AATF genome encoded miR-2909 RNomics pathway involving crucial genes coding for KLF4, Deptor, mTORC1, STAT3, and p53 has the inherent capacity to ensure sustained co-amplification of PVT-1 gene locus together with c-Myc gene. Based upon these results, we propose that miR-2909 RNomics pathway may play a crucial role in the regulation of tumorigenic PVT-1 gene locus.

The PI3K/AKT axis modulates AATF activity in Wilms' tumor cells

Previous studies have reported excessive expression of apoptosis‐antagonizing transcription factor (AATF) in various tumors, where it reinforces the generation and development of cancers and is linked to the clinical outcome. Nevertheless, the expression and influence of AATF in Wilms’ tumor (WT) is largely unknown. Here, we discovered that AATF expression was markedly increased in WT tissues as compared to the surrounding normal tissues. Elevated levels of AATF expression were related to tumor relapse and pulmonary metastasis, congruent with it being a predictor of clinical outcome in people suffering from WT. Proliferation, invasion, and migration of WT cells were suppressed by knockdown of AATF and promoted by AATF overexpression in vitro. Furthermore, the tumor generation capability of WT cells noticeably decreased after knockout of AATF in vivo. The phosphoinositide‐3‐kinase (PI3K)/AKT pathway modulated the activity of AATF in WT. The findings of our study indicate that AATF expression is increased in WT and can serve as a predictor of clinical outcome; in addition, it may enhance the development of WT via the PI3K/AKT axis and may be a promising marker for WT diagnosis and therapy.

A seven-gene prognostic signature for rapid determination of head and neck squamous cell carcinoma survival

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer and displays divergent clinical outcomes. Prognostic biomarkers might improve risk stratification and survival prediction. We aimed to investigate the prognostic genes associated with overall survival. A two-step gene selection method was used to develop a seven-gene-based prognostic model based on the training set collected from The Cancer Genome Atlas (TCGA). In addition, the prognostic model was validated in an independent testing set from Gene Expression Omnibus (GEO). The score based on the model successfully distinguished HNSCC survival into high-risk and low-risk groups in the training set (HR, 2.79; 95% CI, 1.98–3.92; P=4.05×10⁻⁹) and the testing set (HR, 2.05; 95% CI, 1.35–3.11; P=7.98×10⁻⁴). In addition, the score could significantly predict 5-year survival by ROC curves (AUCs for training set, 0.73; testing set, 0.66). Combining risk scores with clinical characteristics improved the AUCs beyond using clinical characteristics alone (training set, from 0.57 to 0.75; testing set, from 0.63 to 0.72). A subgroup sensitivity analysis with HPV status and tumor sites revealed that the risk score was significant in all subgroups except oral cavity tumors of the testing set. Furthermore, HPV-positive status improves survival in oropharyngeal HNSCC but not non-oropharyngeal HNSCC. In conclusion, the seven-gene prognostic signature is a reliable and practical prognostic tool for HNSCC. This approach can add prognostic value to clinical characteristics and provides a new possibility for individualized treatment.

APOBEC3G governs the generation of truncated AATF protein to ensure oncogenic transformation

The oncogenic potential of Apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) was recently appreciated by the finding that revealed its ability to downregulate Kruppel-like factor 4 (KLF4) gene translation through its affinity for 3'UTR of KLF4 mRNA. Keeping in view the fact that KLF4 is known to repress apoptosis antagonizing transcription factor (AATF) gene expression, the present study employed stem cells as archetype model to explore the effect of APOBEC3G over-expression upon AATF gene expression within these cells as well as on the genes involved in oncogenic transformation. Such a study revealed that APOBEC3G had the ability to bind AATF mRNA within its third exon to facilitate the generation of truncated 23 kDa AATF translation product which, in turn, had the inherent capacity to be the crucial mediator of APOBEC3G induced oncogenic transformation within such cells.