TIP60 up-regulates ΔNp63α to promote cellular proliferation

TIP60 enhances cisplatin resistance via regulating ΔNp63α acetylation in SCC

Non-melanoma skin cancer, including basal and squamous cell carcinoma, is the most common form of cancer worldwide, with approximately 5.4 million new cases diagnosed each year in the United States. While the chemotherapeutic drug cisplatin is often used to treat squamous cell carcinoma (SCC) patients, low response rates and disease recurrence are common. In this study, we show that TIP60 and ΔNp63α levels correlate with cisplatin resistance in SCC cell lines, suggesting that TIP60 contributes to the failure of platinum-based drugs in SCC by regulating the stability and transcriptional activity of ΔNp63α. Depletion of endogenous TIP60 or pharmacological inhibition of TIP60 led to a decrease in ΔNp63α protein and acetylation levels in multiple SCC cell lines. We showed that TIP60 upregulates ΔNp63α protein levels in cisplatin-resistant SCC cell lines by protecting it from cisplatin-mediated degradation and increasing its protein stability. Stable expression of TIP60 or ΔNp63α individually promoted resistance to cisplatin and reduced cell death, while loss of either TIP60 or ΔNp63α induced G2/M arrest, increased cell death, and sensitized cells to cisplatin. Moreover, pharmacological inhibition of TIP60 reduced acetylation of ΔNp63α and sensitized resistant cells to cisplatin. Taken together, our study indicates that TIP60-mediated stabilization of ΔNp63α increases cisplatin resistance and provides critical insights into the mechanisms by which ΔNp63α confers cisplatin resistance by promoting cell proliferation and inhibiting apoptosis. Furthermore, our data suggests that inhibition of TIP60 may be therapeutically advantageous in overcoming cisplatin resistance in SCC and other epithelial cancers.

Histone acetyltransferases as promising therapeutic targets in glioblastoma resistance

Glioblastoma (GBM) is a fatal adult brain tumor with an extremely poor prognosis. GBM poses significant challenges for targeted therapies due to its intra- and inter-tumoral heterogeneity, a highly immunosuppressive microenvironment, diffuse infiltration into normal brain parenchyma, protection by the blood-brain barrier and acquisition of therapeutic resistance. Recent studies have implicated epigenetic modifiers as key players driving tumorigenesis, resistance, and progression of GBM. While the vast majority of GBM research on epigenetic modifiers thus far has focused predominantly on elucidating the functional roles and targeting of DNA methyltransferases and histone deacetylases, emerging evidence indicates that histone acetyltransferases (HATs) also play a key role in mediating plasticity and therapeutic resistance in GBM. Here, we will provide an overview of HATs, their dual roles and functions in cancer as both tumor suppressors and oncogenes and focus specifically on their implications in GBM resistance. We also discuss the technical challenges in developing selective HAT inhibitors and highlight their promise as potential anti-cancer therapeutics for treating intractable cancers such as GBM.

HSF1 activates the FOXO3a-ΔNp63α-CDK4 axis to promote head and neck squamous cell carcinoma cell proliferation and tumour growth

Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent cancers worldwide. Heat shock factor 1 (HSF1) is a conserved transcriptional factor that plays a critical role in maintaining cellular proteostasis. However, the role of HSF1 in HNSCC development remains largely unclear. Here, we report that HSF1 promotes forkhead box protein O3a (FOXO3a)-dependent transcription of ΔNp63α (p63 isoform in the p53 family; inhibits cell migration, invasion, and metastasis), which leads to upregulation of cyclin-dependent kinase 4 expression and HNSCC tumour growth. Ablation of HSF1 or treatment with KRIBB11, a specific pharmacological inhibitor of HSF1, significantly suppresses ΔNp63α expression and HNSCC tumour growth. Clinically, the expression of HSF1 is positively correlated with the expression of ΔNp63α in HNSCC tumours. Together, this study demonstrates that the HSF1-ΔNp63α pathway is critically important for HNSCC tumour growth.

ΔNp63α in cancer: importance and therapeutic opportunities

Our understanding of cancer and the key pathways that drive cancer survival has expanded rapidly over the past several decades. However, there are still important challenges that continue to impair patient survival, including our inability to target cancer stem cells (CSCs), metastasis, and drug resistance. The transcription factor p63 is a p53 family member with multiple isoforms that carry out a wide array of functions. Here, we discuss the critical importance of the ΔNp63α isoform in cancer and potential therapeutic strategies to target ΔNp63α expression to impair the CSC population, as well as to prevent metastasis and drug resistance to improve patient survival.

The p110α/ΔNp63α complex mutations in triple-negative breast cancer: Potential targets for transcriptional-based therapies

BACKGROUND

Hotspot mutations occurring in the p110α domain of the PIK3CA gene, specifically p110αH1047R/L increase tumor metastasis and cell motility in triple-negative breast cancer (TNBC). These mutations also affect the transcriptional regulation of ΔNp63α, a significant isoform of the p53 protein involved in cancer progression. This study attempts to investigate the transcriptional impact of p110αH1047R/L mutations on the PIK3CA/ΔNp63α complex in TNBC carcinogenesis.

METHODS

We performed site-directed mutagenesis to introduce p110αH1047R/L mutations and evaluated their oncogenic effects on the growth, invasion, migration, and apoptosis of three different TNBC cell lines in vitro. We investigated the impact of these mutations on the p110α/ΔNp63α complex and downstream transcriptional signaling pathways at the gene and protein levels. Additionally, we used bioinformatics techniques such as molecular dynamics simulations and protein-protein docking to gain insight into the stability and structural changes induced by the p110αH1047R/L mutations in the p110α/ΔNp63α complex and downstream signaling pathway.

RESULTS

The presence of PIK3CA oncogenic hotspot mutations in the p110α/ΔNp63α complex led to increased scattering of TNBC cells during growth, migration, and invasion. Our in vitro mutagenesis assay showed that the p110αH1047R/L mutations activated the PI3K-Akt-mTOR and tyrosine kinase receptor pathways, resulting in increased cell proliferation, invasion, and apoptosis in TNBC cells. These mutations decreased the repressing effect of ΔNp63α on the p110α kinase domain, leading to the enhancement of downstream signaling pathways of PI3K and tyrosine kinase receptors and oncogenic transformation in TNBC. Additionally, our findings suggest that the physical interaction between the DNA binding domain of ΔNp63α and the kinase domain of p110α may be partially impaired, potentially leading to alterations in the conformation of the p110α/ΔNp63α complex.

CONCLUSION

Our findings suggest that targeting the p110αH1047R/L mutations in TNBC could be a promising strategy for developing transcriptional-based therapies. Restoring the interaction between ΔNp63α and the p110α kinase domain, which is disrupted by these mutations, may provide a new approach to treating TNBC.

The CK1δ/ϵ-Tip60 Axis Enhances Wnt/β-Catenin Signaling via Regulating β-Catenin Acetylation in Colon Cancer

Casein kinase 1δ/ϵ (CK1δ/ϵ) are well-established positive modulators of the Wnt/β-catenin signaling pathway. However, the molecular mechanisms involved in the regulation of β-catenin transcriptional activity by CK1δ/ϵ remain unclear. In this study, we found that CK1δ/ϵ could enhance β-catenin-mediated transcription through regulating β-catenin acetylation. CK1δ/ϵ interacted with Tip60 and facilitated the recruitment of Tip60 to β-catenin complex, resulting in increasing β-catenin acetylation at K49. Importantly, Tip60 significantly enhanced the SuperTopFlash reporter activity induced by CK1δ/ϵ or/and β-catenin. Furthermore, a CK1δ/CK1ϵ/β-catenin/Tip60 complex was detected in colon cancer cells. Simultaneous knockdown of CK1δ and CK1ϵ significantly attenuated the interaction between β-catenin and Tip60. Notably, inhibition of CK1δ/ϵ or Tip60, with shRNA or small molecular inhibitors downregulated the level of β-catenin acetylation at K49 in colon cancer cells. Finally, combined treatment with CK1 inhibitor SR3029 and Tip60 inhibitor MG149 had more potent inhibitory effect on β-catenin acetylation, the transcription of Wnt target genes and the viability and proliferation in colon cancer cells. Taken together, our results revealed that the transcriptional activity of β-catenin could be modulated by the CK1δ/ϵ-β-catenin-Tip60 axis, which may be a potential therapeutic target for colon cancer.

SYT7 acts as an oncogene and a potential therapeutic target and was regulated by ΔNp63α in HNSCC

Background

Head and neck squamous cell carcinoma (HNSCC) are one of the most common types of head and neck cancer, and it is urgent to find effective treatment for advanced patients. Exploring developing and progressing mechanisms of HNSCC could provide a theoretical basis to find new therapeutic targets.

Methods

In our research, we performed a whole-gene expression profile microarray analysis to identify differential expression genes between squamous cell carcinoma cells and ΔNp63 alpha (ΔNp63α) knockdown cells. As a result, an important gene Synaptotagmin VII (SYT7) was screened out.

Results

SYT7 knockdown affected the proliferation, apoptosis and cell cycle of squamous cell carcinoma cells. The rescue experiment in vitro with ΔNp63α and SYT7 double knockdown resulted in partial reversion of ΔNp63α-induced phenotypes. This was also confirmed by experiments in vivo.

Conclusions

Taken together, we found that ΔNp63α could inhibit the occurrence and progression of HNSCC throughout downregulating the expression of SYT7. Therefore, SYT7/ΔNp63α axis could be a potential therapeutic target for clinical treatment of HNSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02394-w.

The Acetyltransferase KAT5 Inhibitor NU 9056 Promotes Apoptosis and Inhibits JAK2/STAT3 Pathway in Extranodal NK/T Cell Lymphoma

BACKGROUND

Extranodal natural killer/T cell lymphoma (ENKTL) is an aggressive malignant non-Hodgkin's lymphoma (NHL) with a poor prognosis. Therefore, novel therapeutic biomarkers and agents must be identified for the same. KAT5 inhibitor, NU 9056, is a small molecule that can inhibit cellular proliferation; however, its role in ENKTL has not been studied.

OBJECTIVE

The present study investigated the effect of NU 9056 in ENKTL cells and explored the possible molecular mechanism for its antitumour effect.

METHODS

The role of NU 9056 in ENKTL cells was investigated through the Cell Counting Kit-8 assay, flow cytometry, Western blot, and real-time quantitative polymerase chain reaction assay.

RESULTS

NU 9056 inhibited ENKTL cell proliferation and induced G2/M phase arrest. NU 9056 also induced apoptosis by upregulating DR4, DR5, and caspase 8 expressions. Additionally, NU 9056 increased the expression of Bax, Bid, and cytochrome C and decreased the expression of Bcl-2, Mcl-1, and XIAP. Furthermore, NU 9056 activated endoplasmic reticulum (ER) stress and inhibited the JAK2/STAT3 signalling pathway. The p38 mitogen-activated protein kinase (MAPK) signalling pathway was also activated by NU 9056, and the ERK signalling pathway was suppressed in natural killer/T cell lymphoma cells.

CONCLUSION

NU 9056 inhibited cell proliferation, arrested cell cycle in the G2/M phase, and induced apoptosis through the stimulation of ER stress, thus inhibiting the JAK2/STAT3 signalling pathway and regulating MAPK pathways in ENKTL cells.

Thymoquinone Is a Multitarget Single Epidrug That Inhibits the UHRF1 Protein Complex

Silencing of tumor suppressor genes (TSGs) through epigenetic mechanisms, mainly via abnormal promoter DNA methylation, is considered a main mechanism of tumorigenesis. The abnormal DNA methylation profiles are transmitted from the cancer mother cell to the daughter cells through the involvement of a macromolecular complex in which the ubiquitin-like containing plant homeodomain (PHD), and an interesting new gene (RING) finger domains 1 (UHRF1), play the role of conductor. Indeed, UHRF1 interacts with epigenetic writers, such as DNA methyltransferase 1 (DNMT1), histone methyltransferase G9a, erasers like histone deacetylase 1 (HDAC1), and functions as a hub protein. Thus, targeting UHRF1 and/or its partners is a promising strategy for epigenetic cancer therapy. The natural compound thymoquinone (TQ) exhibits anticancer activities by targeting several cellular signaling pathways, including those involving UHRF1. In this review, we highlight TQ as a potential multitarget single epidrug that functions by targeting the UHRF1/DNMT1/HDAC1/G9a complex. We also speculate on the possibility that TQ might specifically target UHRF1, with subsequent regulatory effects on other partners.

The foggy world(s) of p63 isoform regulation in normal cells and cancer

The p53 family member p63 exists as two major protein variants (TAp63 and ΔNp63) with distinct expression patterns and functional properties. Whilst downstream target genes of p63 have been studied intensively, how p63 variants are themselves controlled has been relatively neglected. Here, we review advances in understanding ΔNp63 and TAp63 regulation, highlighting their distinct pathways. TAp63 has roles in senescence and metabolism, and in germ cell genome maintenance, where it is activated post-transcriptionally by phosphorylation cascades after DNA damage. The function and regulation of TAp63 in mesenchymal and haematopoietic cells is less clear but may involve epigenetic control through DNA methylation. ΔNp63 functions to maintain stem/progenitor cells in various epithelia and is overexpressed in squamous and certain other cancers. ΔNp63 is transcriptionally regulated through multiple enhancers in concert with chromatin modifying proteins. Many signalling pathways including growth factors, morphogens, inflammation, and the extracellular matrix influence ΔNp63 levels, with inconsistent results reported. There is also evidence for reciprocal regulation, including ΔNp63 activating its own transcription. ΔNp63 is downregulated during cell differentiation through transcriptional regulation, while post-transcriptional events cause proteasomal degradation. Throughout the review, we identify knowledge gaps and highlight discordances, providing potential explanations including cell-context and cell-matrix interactions. Identifying individual p63 variants has roles in differential diagnosis and prognosis, and understanding their regulation suggests clinically approved agents for targeting p63 that may be useful combination therapies for selected cancer patients. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.