p53 and cell cycle effects after DNA damage

A general, robust framework for determining the key species that forewarns sudden transitions in biological circuits

The Cdc2-cyclin B/Wee1 kinase system exhibits bistability between alternative steady states, which emerges due to the mutual inhibition between Cdc2-cyclin B and Wee1 kinases. Alternative steady states are the M phase-like state and G2 arrest state, which have implications in cell cycle progression at the G2 phase in eukaryotic cells. A slight alteration in the feedback strength can drive sudden transitions between these contrasting alternative states upon crossing a critical threshold or a tipping point. The phenomenon of critical slowing down (CSD) has been widely used to identify the proximity to a tipping point. However, determining the key variable or species that best signals CSD is a challenging task and holds significance in complex biochemical processes. Here, we determine the key variable or observation direction (OD) from the direction of CSD to best detect an upcoming transition in the Cdc2-cyclin B/Wee1 model system. We find that with increasing feedback strength, the Cdc2-cyclin B is the OD, as it produces a stronger signal than that of Wee1. With decreasing feedback strength, both Cdc2-cyclin B and Wee1 produce similar signals and can be used as the OD. Furthermore, the noise-sensitive direction highlights the effect of stochasticity in Cdc2-cyclin B and Wee1 for increasing and decreasing feedback strength, respectively. We also perform sensitivity analyses that reveal the robustness of the OD. Finally, we compare the efficacy of OD with principal component analysis while detecting a tipping point, and also validate its general applicability to epithelial-mesenchymal transition for cancer progression.

RNA demethylase ALKBH5 regulates cell cycle progression in DNA damage response

RNA N6-methyladenosine (m6A) modification plays a crucial role in the DNA damage response, while the detailed mechanisms remain to be explored. In this study, we report the involvement of the m6A demethylase ALKBH5 in X-ray-induced DNA damage response. Depletion of ALKBH5 reduces X-ray-induced DNA damage, induces G2/M phase arrest and reduces cell apoptosis. RNA sequencing and m6A sequencing analysis reveal that ALKBH5 removes m6A modifications from its target mRNAs and suppresses their expression. A subset of mRNAs encoding cyclin dependent kinase inhibitors, such as CDKN1A and CDKN2B, show increased stability and expression upon ALKBH5 knockdown. Subsequently, the upregulation of CDKN1A and CDKN2B contributes to G2/M phase arrest to facilitate DNA repair. Our findings unveil the epigenetic regulation of cell cycle checkpoint by ALKBH5 in X-ray-induced DNA damage, offering potential targets for DNA damage-based therapy for cancers.

Probiotics as Anti-Tumor Agents: Insights from Female Tumor Cell Culture Studies

Breast and ovarian cancers are among the most prevalent cancers in women. Cancerous cells are characterized by their ability to continuously cycle and migrate, forming metastases. Some probiotic strains have shown anti-tumorigenic effects. This study tested the impact of probiotics on OVCAR-3 and MDA-MB-231 cell lines by analyzing proteins involved in cell cycle regulation (pP53, Cyclin D1, pERK1), cell survival (AKT), and cell migration (RhoA) using Western blotting and scratch wound tests. Results indicated a reduction in these proteins and decreased cell migration velocity post-treatment. These findings suggest that certain probiotic combinations can arrest the cell cycle, promote cell death, and reduce cell migration, potentially serving as promising candidates alongside standard therapies.

The involvement of cyclin-dependent kinase 7 (CDK7) and 9 (CDK9) in coordinating transcription and cell cycle checkpoint regulation

Cells regulate the expression of cell cycle-related genes, including cyclins essential for mitosis, through the transcriptional activity of the positive transcription elongation factor b (P-TEFb), a complex comprising CDK9, cyclin T, and transcription factors. P-TEFb cooperates with CDK7 to activate RNA polymerase. In response to DNA stress, the cell cycle shifts from mitosis to repair, triggering cell cycle arrest and the activation of DNA repair genes. This tight coordination between transcription, cell cycle progression, and DNA stress response is crucial for maintaining cellular integrity. Cyclin-dependent kinases CDK7 and CDK9 are central to both transcription and cell cycle regulation. CDK7 functions as the CDK-activating kinase (CAK), essential for activating other CDKs, while CDK9 acts as a critical integrator of signals from both the cell cycle and transcriptional machinery. This review elucidates the mechanisms by which CDK7 and CDK9 regulate the mitotic process and cell cycle checkpoints, emphasizing their roles in balancing cell growth, homeostasis, and DNA repair through transcriptional control.

ABCB1 confers resistance to carboplatin by accumulating stem-like cells in the G2/M phase of the cell cycle in p53null ovarian cancer

High-grade ovarian serous carcinoma, mostly bearing the various mutations in the TP53 gene, typically relapses within six months after first-line therapy due to chemoresistance, with a median overall survival of less than a year. However, the molecular mechanisms of action behind acquired drug resistance, particularly in relation to different TP53 mutation types, have not been fully elucidated. In this study, we demonstrated that acquired resistance to carboplatin in SKOV3 harboring a p53null mutation, but not in OVCAR3 with a p53R248Q, induces a significant portion of cells accumulated in the G2/M phase of the cell cycle, where cells highly expressed stemness marker with elevated proliferative capacity, which we believe was reversed by ABCB1 inhibition to the levels observed in non-resistant parental cells. ABCB1 suppression re-sensitized carboplatin-resistant cells to additional genotoxic stress and reduced their proliferative ability by recovering DNA repair activity and lowering stemness-like features, especially in the G2/M-distributed fraction. This suggests that high levels of stemness and attenuated DNA repair function exhibited in the G2/M-accumulated portion may be a key contributor of chemoresistance in patients with ovarian cancer bearing a p53null mutation, but not other types of mutations expressing p53. Furthermore, the inhibition of ΔNp73 resulted in the suppression of ABCB1, which consequently restricted cell growth in carboplatin-resistant SKOV3, suggesting that the ΔNp73 may act as an upstream regulator of the ABCB1. Notably, combinatorial treatment of carboplatin with the p53 reactivator, APR-246, proved effective in overcoming chemoresistance in OVCAR3 with the p53R248Q. Our findings suggest that the ΔNp73-ABCB1 axis is a promising molecular target for carboplatin-resistant ovarian cancers harboring p53null mutations, which we uncovered could be utilized to increase the efficacy of conventional anti-cancer therapies, to develop more efficient combinatorial therapeutic interventions directed toward overcoming the chemoresistance and improving the survival rates in patients with ovarian cancer.

N4-acetylcytidine and other RNA modifications in epitranscriptome: insight into DNA repair and cancer development

N4-acetylcytidine (ac4C) is a post-transcriptional RNA modification that plays a crucial role in the epitranscriptome, influencing gene expression and cellular function. This modification occurs at the cytosine base, where an acetyl group is installed to the nitrogen at the 4th position (N4). This co-transcription modification affects RNA stability, RNA structure, and translation efficiency. Recent studies have uncovered a potential link between RNA modifications and DNA repair mechanisms, suggesting that ac4C-modified or methylated RNAs may interact with factors involved in DNA repair pathways; thus, influencing the cellular response to DNA damage. Dysregulation of modified RNAs, including ac4C RNA, has been implicated in cancer development, where aberrant levels of these RNAs may contribute to oncogenic transformation by altering genome stability and the expression of key genes regulating cell proliferation, cell cycle progression, and apoptosis. Understanding the dynamics of modified RNAs offers promising insights into the role of epitranscriptome in DNA repair processes and cancer treatment.

Unraveling the role of deubiquitinating enzymes on cisplatin resistance in several cancers

The use of platinum-based drugs in cancer treatment is one of the most common methods in chemotherapy. Especially, cisplatin induces cell death by interrupting DNA synthesis by binding to the DNA bases, thereby leading to the apoptosis via multiple pathways. However, the major hurdle in chemotherapy is drug resistance. To overcome drug resistance, the ubiquitin-proteasome system (UPS) has emerged as a potential therapeutic target. The UPS is a pivotal signaling pathway that regulates the majority of cellular proteins by attaching ubiquitin to substrates, leading to proteasomal degradation. Conversely, deubiquitinating enzymes (DUBs) remove tagged ubiquitin from the substrate and inhibit degradation, thereby maintaining proteostasis. Recently, studies have been conducted to identify the substrates of DUBs and investigated the cellular mechanisms, and now the development of therapeutics using DUB inhibitors is in clinical trials. However, the mechanism of the DUB response to cisplatin remains still unclear. In this review, we summarize the research reported on the function of DUBs responding to cisplatin.

Radionuclide treatments of cancer: molecular mechanisms, biological responses, histopathological changes, and role of PET imaging

Radiation treatments [radiotherapy and radionuclide treatments (RNTs)] are one of the main and effective treatment modalities of cancer. Globally, the number of cancer patients treated with radionuclides are much less as compared to number of radiotherapy cases but with the development of new radiotracers, most notably 177 Lu and 225 Ac-labeled prostate-specific membrane antigen ligands, and 223 Ra-dichloride for prostate cancer and 177 Lu-somatostatin analogs for neuroendocrine tumors, there is a significant rise in RNTs in the last decade. As therapeutic applications of nuclear medicine is on the rise, the aim of this review is to summarize biological responses to radiation treatments and molecular mechanisms of radiation-induced cell death (e.g. ionization, DNA damages such as double-strand breaks, DNA repair mechanisms, types of cell deaths such as apoptosis, necrosis, and immunogenic cell death), histopathological changes with radiation treatments, and role of PET imaging in RNTs as part of radionuclide theranostics for selecting and planning patients for RNTs, dosimetry, predicting and assessing response to RNTs, predicting toxicities, and other possible PET findings which may be seen after RNTs such as activation of immune system.

Defining the Molecular Intricacies of Human Papillomavirus-Associated Tonsillar Carcinoma

BackgroundThe past decade has shown a sharp incline in the human papillomavirus (HPV) infection associated oropharyngeal carcinoma cases, especially in men younger than 60 years old. Tonsils are one of the key sites, within the oropharyngeal region, which shows malignant changes due to HPV infection, and there is very limited literature to understand the specific dynamics in the tonsillar areas.ObjectiveThis critical review was undertaken to explore and unravel the bio-molecular interactions and the role of specific proteins associated with HPV infection induced tumorigenesis for the tonsils.DesignA systematic search of the literature was performed utilising keywords and MeSH terms related to HPV and tonsillar carcinoma in PubMed, Scopus, Embase, and Web of Science without restrictions on dates until July 2023. All studies that reported on molecular biomarkers or genes/genetic proteins in the context of HPV associated tonsillar carcinoma were included in the study.ResultsPreliminary searches revealed a total of 2734 studies of which 23 satisfied the final inclusion criteria and were included. More than 25 proteins and biomarkers were identified, and their role in the malignant process was extracted and compiled. This review also presents a short excerpt on each of the molecules identified to provide a better understanding of the pathogenesis.ConclusionGiven the rapidly increasing number of cases, there is an urgent need for more focused research on virally induced tonsillar cancers, to develop a better understanding, and for clarity of management and treatment.

DNA Damage and Inflammatory Response of p53 Null H358 Non-Small Cell Lung Cancer Cells to X-Ray Exposure Under Chronic Hypoxia

Hypoxia-induced radioresistance limits therapeutic success in cancer. In addition, p53 mutations are widespread in tumors including non-small cell lung carcinomas (NSCLCs), and they might modify the radiation response of hypoxic tumor cells. We therefore analyzed the DNA damage and inflammatory response in chronically hypoxic (1% O2, 48 h) p53 null H358 NSCLC cells after X-ray exposure. We used the colony-forming ability assay to determine cell survival, γH2AX immunofluorescence microscopy to quantify DNA double-strand breaks (DSBs), flow cytometry of DAPI-stained cells to measure cell cycle distribution, ELISAs to quantify IL-6 and IL-8 secretion in cell culture supernatants, and RNA sequencing to determine gene expression. Chronic hypoxia increased the colony-forming ability and radioresistance of H358 cells. It did not affect the formation or resolution of X-ray-induced DSBs. It reduced the fraction of cells undergoing G2 arrest after X-ray exposure and delayed the onset of G2 arrest. Hypoxia led to an earlier enhancement in cytokines secretion rate after X-irradiation compared to normoxic controls. Gene expression changes were most pronounced after the combined exposure to hypoxia and X-rays and pertained to senescence and different cell death pathways. In conclusion, hypoxia-induced radioresistance is present despite the absence of functional p53. This resistance is related to differences in clonogenicity, cell cycle regulation, cytokine secretion, and gene expression under chronic hypoxia, but not to differences in DNA DSB repair kinetics.

High expression of RUNX1 in colorectal cancer subtype accelerates malignancy by inhibiting HMGCR

Colorectal cancer (CRC) presents a complex landscape, characterized by both inter-tumor and intra-tumor heterogeneity. RUNX1, a gene implicated in modulating tumor cell growth, survival, and differentiation, remains incompletely understood regarding its impact on CRC prognosis. In our investigation, we discerned a positive correlation between elevated RUNX1 expression and aggressive phenotypes across various CRC subtypes. Notably, knockdown of RUNX1 demonstrated efficacy in restraining CRC proliferation both in vitro and in vivo, primarily through inducing apoptosis and impeding cell proliferation. Mechanistically, we unveiled a direct regulatory link between RUNX1 and cholesterol synthesis, mediated by its control over HMGCR expression. Knockdown of RUNX1 in CRC cells triggered HMGCR transcriptional activation, culminating in elevated cholesterol levels that subsequently hindered cancer progression. Clinically, heightened RUNX1 expression emerged as a prognostic marker for adverse outcomes in CRC patients. Our findings underscore the pivotal involvement of RUNX1 in CRC advancement and its potential as a therapeutic target. The unique influence of RUNX1 on cholesterol synthesis and HMGCR transcriptional regulation uncovers a novel pathway contributing to CRC progression.

Exploring the multifaceted antitumor activity of axitinib in lung carcinoids

Introduction

Lung carcinoids (LCs) are a type of neuroendocrine tumor (NET) that originate in the bronchopulmonary tract. LCs account for 20-25% of all NETs and approximately 1-2% of lung cancers. Given the highly vascularized nature of NETs and their tendency to overexpress vascular growth factor receptors (VEGFR), inhibiting angiogenesis appears as a potential therapeutic target in slowing down tumor growth and spread. This study evaluated the long-term antitumor activity and related mechanisms of axitinib (AXI), a VEGFR-targeting drug, in LC cell lines.

Methods

Three LC cell lines (NCI-H727, UMC-11 and NCI-H835) were incubated with their respective EC50 AXI concentrations for 6 days. At the end of the incubation, FACS experiments and Western blot analyses were performed to examine changes in the cell cycle and the activation of apoptosis. Microscopy analyses were added to describe the mechanisms of senescence and mitotic catastrophe when present.

Results

The primary effect of AXI on LC cell lines is to arrest tumor growth through an indirect DNA damage. Notably, AXI triggers this response in diverse manners among the cell lines, such as inducing senescence or mitotic catastrophe. The drug seems to lose its efficacy when the DNA damage is mitigated, as observed in NCI-H835 cells.

Conclusion

The ability of AXI to affect cell viability and proliferation in LC tumor cells highlights its potential as a therapeutic agent. The role of DNA damage and the consequent activation of senescence seem to be a prerequisite for AXI to exert its function.

RAD52-dependent mitotic DNA synthesis is required for genome stability in Cyclin E1-overexpressing cells

Overexpression of Cyclin E1 perturbs DNA replication, resulting in DNA lesions and genomic instability. Consequently, Cyclin E1-overexpressing cancer cells increasingly rely on DNA repair, including RAD52-mediated break-induced replication during interphase. We show that not all DNA lesions induced by Cyclin E1 overexpression are resolved during interphase. While DNA lesions upon Cyclin E1 overexpression are induced in S phase, a significant fraction of these lesions is transmitted into mitosis. Cyclin E1 overexpression triggers mitotic DNA synthesis (MiDAS) in a RAD52-dependent fashion. Chemical or genetic inactivation of MiDAS enhances mitotic aberrations and persistent DNA damage. Mitosis-specific degradation of RAD52 prevents Cyclin E1-induced MiDAS and reduces the viability of Cyclin E1-overexpressing cells, underscoring the relevance of RAD52 during mitosis to maintain genomic integrity. Finally, analysis of breast cancer samples reveals a positive correlation between Cyclin E1 amplification and RAD52 expression. These findings demonstrate the importance of suppressing mitotic defects in Cyclin E1-overexpressing cells through RAD52.

Subverting the Canon: Novel Cancer-Promoting Functions and Mechanisms for snoRNAs

Small nucleolar RNAs (snoRNAs) constitute a class of intron-derived non-coding RNAs ranging from 60 to 300 nucleotides. Canonically localized in the nucleolus, snoRNAs play a pivotal role in RNA modifications and pre-ribosomal RNA processing. Based on the types of modifications they involve, such as methylation and pseudouridylation, they are classified into two main families-box C/D and H/ACA snoRNAs. Recent investigations have revealed the unconventional synthesis and biogenesis strategies of snoRNAs, indicating their more profound roles in pathogenesis than previously envisioned. This review consolidates recent discoveries surrounding snoRNAs and provides insights into their mechanistic roles in cancer. It explores the intricate interactions of snoRNAs within signaling pathways and speculates on potential therapeutic solutions emerging from snoRNA research. In addition, it presents recent findings on the long non-coding small nucleolar RNA host gene (lncSNHG), a subset of long non-coding RNAs (lncRNAs), which are the transcripts of parental SNHGs that generate snoRNA. The nucleolus, the functional epicenter of snoRNAs, is also discussed. Through a deconstruction of the pathways driving snoRNA-induced oncogenesis, this review aims to serve as a roadmap to guide future research in the nuanced field of snoRNA-cancer interactions and inspire potential snoRNA-related cancer therapies.

Enhancing apoptosis-mediated anticancer activity of evodiamine through protein-based nanoparticles in breast cancer cells

In the cutting-edge era of developing precision therapeutics, nanoparticles have emerged as a potent drug delivery system. Altering the size of poorly water-soluble drugs to nanoscale could confer change in their physical properties, including enhanced water solubility and bioavailability. Evodiamine (EVO), a natural indolequinone alkaloid extract from Evodia rutaecarpa, has shown several important pharmacological applications, anti-cancer being one of them. Protein-based nano-drug delivery systems have gained the interest of researchers due to their better biocompatibility, biodegradability, non-immunogenicity and non-toxicity. In the present study, EVO encapsulated BSA nanoparticles (ENPs) were synthesized and characterized, which were nanoscale-sized (~ 150 nm), monodispersed, spherical shaped, and showed high entrapment efficiency (~ 86%) and controlled drug release. The in-vitro anti-cancer activity of ENPs on human breast cancer cells was dose- and time-dependent. The apoptotic molecular mechanism investigated using FACS, qRT-PCR, and western blotting analysis, revealed increased expression of p53 and Bax and decreased expression of Bcl-2. Biological studies demonstrated comparatively more efficient and targeted delivery of ENPs than pure EVO. The comprehensive physiochemical characterization and in-vitro validation collectively pinpoint ENPs as a promising avenue for harnessing the therapeutic potential of the natural anti-cancer compound EVO. The findings indicate improved cytotoxicity, positioning ENPs as a propitious strategy for advancing breast cancer treatment.

Fanconi anemia pathway regulation by FANCI in prostate cancer

Prostate cancer is one of the leading causes of death among men worldwide, and thus, research on the genetic factors enabling the formation of treatment-resistant cancer cells is crucial for improving patient outcomes. Here, we report a cell line-specific dependence on FANCI and related signaling pathways to counteract the effects of DNA-damaging chemotherapy in prostate cancer. Our results reveal that FANCI depletion results in significant downregulation of Fanconi anemia (FA) pathway members in prostate cancer cells, indicating that FANCI is an important regulator of the FA pathway. Furthermore, we found that FANCI silencing reduces proliferation in p53-expressing prostate cancer cells. This extends the evidence that inactivation of FANCI may convert cancer cells from a resistant state to an eradicable state under the stress of DNA-damaging chemotherapy. Our results also indicate that high expression of FA pathway genes correlates with poorer survival in prostate cancer patients. Moreover, genomic alterations of FA pathway members are prevalent in prostate adenocarcinoma patients; mutation and copy number information for the FA pathway genes in seven patient cohorts (N = 1,732 total tumor samples) reveals that 1,025 (59.2%) tumor samples have an alteration in at least one of the FA pathway genes, suggesting that genomic alteration of the pathway is a prominent feature in patients with the disease.

Chemosensitivity to doxorubicin in primary cells derived from tumor of FVB/N-Trp53tm1Hw1 with TALEN-mediated Trp53 mutant gene

BACKGROUND

To evaluate the chemosensitivity to doxorubicin (DOX) in two primary cells derived from a tumor of FVB/N-Trp53tm1Hw1 knockout (KO) mice with TALEN-mediated Trp53 mutant gene, we evaluated the cell survivability, cell cycle distribution, apoptotic cell numbers and apoptotic protein expression in solid tumor cells and ascetic tumor cells treated with DOX.

RESULTS

The primary tumor cells showed a significant (P < 0.05) defect for UV-induced upregulation of the Trp53 protein, and consisted of different ratios of leukocytes, fibroblasts, epithelial cells and mesenchymal cells. The IC50 level to DOX was lower in both primary cells (IC50 = 0.12 μM and 0.20 μM) as compared to the CT26 cells (IC50 = 0.32 μM), although the solid tumor was more sensitive. Also, the number of cells arrested at the G0/G1 stage was significantly decreased (24.7-23.1% in primary tumor cells treated with DOX, P < 0.05) while arrest at the G2 stage was enhanced to 296.8-254.3% in DOX-treated primary tumor cells compared with DOX-treated CT26 cells. Furthermore, apoptotic cells of early and late stage were greatly increased in the two primary cell-lines treated with DOX when compared to same conditions for CT26 cells. However, the Bax/Bcl-2 expression level was maintained constant in the primary tumor and CT26 cells.

CONCLUSIONS

To the best of our knowledge, these results are the first to successfully detect an alteration in chemosensitivity to DOX in solid tumor cells and ascetic tumor cells derived from tumor of FVB/N-Trp53tm1Hw1 mice TALEN-mediated Trp53 mutant gene.

DNA damage and repair: underlying mechanisms leading to microcephaly

DNA-damaging agents and endogenous DNA damage constantly harm genome integrity. Under genotoxic stress conditions, the DNA damage response (DDR) machinery is crucial in repairing lesions and preventing mutations in the basic structure of the DNA. Different repair pathways are implicated in the resolution of such lesions. For instance, the non-homologous DNA end joining and homologous recombination pathways are central cellular mechanisms by which eukaryotic cells maintain genome integrity. However, defects in these pathways are often associated with neurological disorders, indicating the pivotal role of DDR in normal brain development. Moreover, the brain is the most sensitive organ affected by DNA-damaging agents compared to other tissues during the prenatal period. The accumulation of lesions is believed to induce cell death, reduce proliferation and premature differentiation of neural stem and progenitor cells, and reduce brain size (microcephaly). Microcephaly is mainly caused by genetic mutations, especially genes encoding proteins involved in centrosomes and DNA repair pathways. However, it can also be induced by exposure to ionizing radiation and intrauterine infections such as the Zika virus. This review explains mammalian cortical development and the major DNA repair pathways that may lead to microcephaly when impaired. Next, we discuss the mechanisms and possible exposures leading to DNA damage and p53 hyperactivation culminating in microcephaly.

TP53 and p21 (CDKN1A) polymorphisms and the risk of systemic lupus erythematosus

BACKGROUND

The p53 and p21 proteins are important regulators of cell cycle and apoptosis and may contribute to autoimmune diseases, such as systemic lupus erythematosus (SLE). As genetic polymorphisms may cause changes in protein levels and functions, we investigated associations of TP53 and p21 (CDKN1A) polymorphisms (p53 72 G > C-rs1042522; p53 PIN3-rs17878362; p21 31 C > A-rs1801270; p21 70 C > T-rs1059234) with the development of systemic lupus erythematosus (SLE) in a Southeastern Brazilian population.

METHODS

Genotyping of 353 female volunteers (cases, n = 145; controls, n = 208) was performed by polymerase chain reaction, restriction fragment length polymorphism and/or DNA sequencing. Associations between TP53 and p21 polymorphisms and SLE susceptibility and clinical manifestations of SLE patients were assessed by logistic regression analysis.

RESULTS

Protective effect was observed for the genotype combinations p53 PIN3 A1/A1-p21 31 C/A, in the total study population (OR 0.45), and p53 PIN3 A1/A2-p21 31 C/C, in non-white women (OR 0.28). In Whites, p53 72 C-containing (OR 3.06) and p53 PIN3 A2-containing (OR 6.93) genotypes were associated with SLE risk, and higher OR value was observed for the combined genotype p53 72 G/C-p53 PIN3 A1/A2 (OR 9.00). Further, p53 PIN3 A1/A2 genotype was associated with serositis (OR 2.82), while p53 PIN3 A2/A2 and p53 72 C/C genotypes were associated with neurological disorders (OR 4.69 and OR 3.34, respectively).

CONCLUSIONS

Our findings showed that the TP53 and p21 polymorphisms included in this study may have potential to emerge as SLE susceptibility markers for specific groups of patients. Significant interactions of the TP53 polymorphisms with serositis and neurological disorders were also observed in SLE patients.

The impact and outcomes of cancer-macrophage fusion

BACKGROUND

Cancer's hallmark feature is its ability to evolve, leading to metastasis and recurrence. Although genetic mutations and epigenetic changes have been implicated, they don't fully explain the leukocytic traits that many cancers develop. Cell fusion between cancer and somatic cells, particularly macrophages, has been suggested as an alternative pathway for cancer cells to obtain new traits by acquiring exogenous genetic material.

METHODS

This study aims to investigate the potential biological outcomes of tumor-myeloid cell fusion by generating tumor-macrophage hybrid cells. Two clones with markedly different tumorigenicity were selected, and RNA-seq was used to compare their RNA expressions with that of the control cells. Based on the results that the hybrid cells showed differential activation in several upstream regulator pathways that impact their biological behaviors, the hybrid cells' abilities to recruit stromal cells and establish angiogenesis as well as their cell cycle distributions were investigated through in vitro and in vivo studies.

RESULTS

Although both hybrid clones demonstrated p53 activation and reduced growth rates, they exhibited distinct cell cycle distributions and ability to grow in vivo. Notably, while one clone was highly tumorigenic, the other showed little tumorigenicity. Despite these differences, both hybrid clones were potent environmental modifiers, exhibiting significant abilities to recruit stromal and immune cells and establish angiogenesis.

CONCLUSIONS

The study revealed that tumor-somatic cell fusion is a potent environmental modifier that can modulate tumor survival and evolution, despite its relatively low occurrence. These findings suggest that tumor-somatic cell fusion could be a promising target for developing new cancer therapies. Furthermore, this study provides an experimental animal platform to investigate cancer-myeloid fusion and highlights the potential role of tumor-somatic cell fusion in modulating the tumor environment.

LncRNA LIMp27 Regulates the DNA Damage Response through p27 in p53-Defective Cancer Cells

P53 inactivation occurs in about 50% of human cancers, where p53-driven p21 activity is devoid and p27 becomes essential for the establishment of the G1/S checkpoint upon DNA damage. Here, this work shows that the E2F1-responsive lncRNA LIMp27 selectively represses p27 expression and contributes to proliferation, tumorigenicity, and treatment resistance in p53-defective colon adenocarcinoma (COAD) cells. LIMp27 competes with p27 mRNA for binding to cytoplasmically localized hnRNA0, which otherwise stabilizes p27 mRNA leading to cell cycle arrest at the G0/G1 phase. In response to DNA damage, LIMp27 is upregulated in both wild-type and p53-mutant COAD cells, whereas cytoplasmic hnRNPA0 is only increased in p53-mutant COAD cells due to translocation from the nucleus. Moreover, high LIMp27 expression is associated with poor survival of p53-mutant but not wild-type p53 COAD patients. These results uncover an lncRNA mechanism that promotes p53-defective cancer pathogenesis and suggest that LIMp27 may constitute a target for the treatment of such cancers.

Gracillin exerts anti-melanoma effects in vitro and in vivo: role of DNA damage, apoptosis and autophagy

BACKGROUND

Melanoma is an aggressive cancer. Gracillin has been reported to treat various types of cancer, such as colorectal and lung cancer. However, there is a paucity of research on the anti-melanoma effects of gracillin.

PURPOSE

The aim of this study was to assess the anti-melanoma effects and mechanisms of action of gracillin in vitro and in vivo.

METHODS

Cell viability was detected using MTT and crystal violet staining assays. Cell proliferation was examined by EdU staining assays. Cell cycle arrest and apoptosis were analyzed by flow cytometry. Autophagic flux was monitored under a confocal microscope. Protein levels were determined by immunoblotting. LY294002 and rapamycin (Rapa) were used to determine the involvement of PI3K/AKT/mTOR signaling in gracillin-mediated autophagy. Signal transducer and activator of transcription 3 (STAT3) was overactivated to explore the contribution of the STAT3 signaling pathway in the anti-melanoma effects of gracillin. A B16F10 allograft mouse model was developed to evaluate the anti-melanoma effects of gracillin in vivo.

RESULTS

We demonstrated that in melanoma cells, gracillin inhibited proliferation, induced G0/G1 phase cell cycle arrest, evoked apoptosis, and triggered autophagic cell death. Gracillin induced DNA damage in melanoma cells. Moreover, it suppressed the phosphorylation/activation of PI3K, AKT, mTOR, and 4E-BP1 in melanoma cells. Inhibiting PI3K/AKT and mTOR activity using LY294002 and Rapa, respectively, increased the protein level of LC3B-II in gracillin-treated melanoma cells. Furthermore, gracillin downregulated the protein levels of p-JAK2 (Tyr1007/1008), p-Src (Tyr416), and p-STAT3 (Tyr705) in melanoma cells. Over-expression of STAT3 in A375 cells significantly mitigated the cytotoxic and apoptotic effects of gracillin. In vivo studies showed that gracillin (1 mg/kg or 8 mg/kg, administered intraperitoneally for 16 consecutive days) suppressed B16F10 tumor growth and Src/STAT3 and AKT/mTOR signaling in tumors. No overt toxicity was observed in mice.

CONCLUSION

Induction of DNA damage, inhibition of PI3K/AKT/mTOR signaling and suppression of STAT3 signaling are involved in gracillin-mediated cell cycle arrest, autophagic cell death and apoptosis, respectively, in melanoma cells. These findings provide novel insights into the anti-melanoma molecular mechanisms of gracillin, and suggest a potential role of gracillin in melanoma management.

Chk1 inhibition-induced BRCAness synergizes with olaparib in p53-deficient cancer cells

Although targeting DNA-damage repair by inhibition of PARP exhibits weak or modest single-agent activity due to the existence of functional BRCA1/2 alleles, PARP inhibitors have been gradually applicable in BRCA-proficient cancers. Checkpoint kinase 1 (Chk1) inhibition selectively disrupts homologous recombination (HR)-mediated DNA repair and confers synthetic lethality in p53-deficient tumors, we therefore aim at expounding the chemopotentiating effects of Chk1 inhibition on PARPi in BRCA-proficient and p53-deficient cancer cells. Initially, BRCA wild-type, p53-null cells including AsPC-1 and H1299 demonstrated innate resistance to PARP inhibitor olaparib compared to BRCA1-mutant, p53-null MDA-MB-436 cells. We quantified the interaction between olaparib and a selective Chk1 inhibitor MK-8776, which produced synergistic effects under sub-IC50 concentrations in p53-depleted AsPC-1 and H1299 cells. Olaparib in combination with MK-8776 showed enhanced antitumor effects through prohibiting proliferation and secondarily inducing apoptosis in two cell lines. Of note, we observed that MK-8776 significantly sensitized cells to olaparib by broad DNA and chromosomal breaks. Mechanistically, MK-8776 abrogated olaparib-induced BRCA1 intranuclear foci formation, MCM7-mediated replication machineries, and ultimately triggered an accumulation of γH2AX, a well-recognized marker of DNA double-strand breaks. Additionally, we established ectopic expression of hotspot mutant p53 in H1299 cells. Introduction of p53R175 H promoted olaparib resistance as single-agent treatment, but the synergy between olaparib and MK-8776 was still achievable and the region of synergy was produced by lower combination concentrations. These data provide insight into how Chk1 inhibition could be effectively targeted and confer sensitivity to olaparib toward p53-deficient and HR-proficient cancers.

GOF Mutant p53 in Cancers: A Therapeutic Challenge

Simple Summary

In normal cells, p53 is a protein which regulates the cell cycle progression to ensure normal cell division, growth, and development. However, in cancer, changes in the p53 DNA sequence, called genetic mutation, results in the protein either losing its normal function or exhibiting advanced pro-tumorigenic functions that lead to cancer. Importantly, cancers with mutations in the p53 protein often represent ones which are more aggressive and more resistant to chemotherapy. As a result, many studies have and continue to investigate multiple ways to target mutant p53-bearing cancer using targeted therapy, gene therapy, immunotherapy, and combination therapies. Knowledge of these strategies is important in improving the overall therapeutic response of cancers with mutant p53. This review highlights new strategies and discusses the progression of such therapies.

Abstract

TP53 is mutated in the majority of human cancers. Mutations can lead to loss of p53 expression or expression of mutant versions of the p53 protein. These mutant p53 proteins have oncogenic potential. They can inhibit any remaining WTp53 in a dominant negative manner, or they can acquire new functions that promote tumour growth, invasion, metastasis and chemoresistance. In this review we explore some of the mechanisms that make mutant p53 cells resistant to chemotherapy. As mutant p53 tumours are resistant to many traditional chemotherapies, many have sought to explore new ways of targeting mutant p53 tumours and reinstate chemosensitivity. These approaches include targeting of mutant p53 stability, mutant p53 binding partners and downstream pathways, p53 vaccines, restoration of WTp53 function, and WTp53 gene delivery. The current advances and challenges of these strategies are discussed.

Selective macrocyclic peptide modulators of Lys63-linked ubiquitin chains disrupt DNA damage repair

Developing an effective binder for a specific ubiquitin (Ub) chain is a promising approach for modulating various biological processes with potential applications in drug discovery. Here, we combine the Random Non-standard Peptides Integrated Discovery (RaPID) method and chemical protein synthesis to screen an extended library of macrocyclic peptides against synthetic Lys63-linked Di-Ub to discover a specific binder for this Ub chain. Furthermore, next-generation binders are generated by chemical modifications. We show that our potent cyclic peptide is cell-permeable, and inhibits DNA damage repair, leading to apoptotic cell death. Concordantly, a pulldown experiment with the biotinylated analog of our lead cyclic peptide supports our findings. Collectively, we establish a powerful strategy for selective inhibition of protein-protein interactions associated with Lys63-linked Di-Ub using cyclic peptides. This study offers an advancement in modulating central Ub pathways and provides opportunities in drug discovery areas associated with Ub signaling.

New fluorobenzamidine exerts antitumor activity against breast cancer in mice via pro-apoptotic activity

BACKGROUND

Breast cancer is one of the leading causes of cancer-related morbidities. The present study aimed to evaluate the efficacy of bithiophene-fluorobenzamidine (BFB) against breast cancer induced by 7,12-dimethylbenz(a)anthracene (DMBA) in female Swiss mice and reveal the underlining mechanisms.

METHODS

The mice were randomly divided into five groups; control, BFB-treated group, DMBA-treated group, and the last two groups received DMBA then tamoxifen or BFB.

RESULTS

BFB reduced the tumor incidence by ~ 88% versus 30% after TAM. DMBA significantly increased the expression of CDK1 and HER2 and reduced the expression of p53, p21 (CDKN1A), ESR-α, and CAS3. BFB caused significant down-regulation of CDK1 and HER2 and upregulation of p53, p21, ESR-α, and CAS3. In the DMBA-treated mice, cancerous cells metastasized to several organs. This was prevented by the administration of BFB. The antimetastatic and proapoptotic activities were confirmed in MCF7 cells in vitro by the wound healing and annexin V assays, respectively. Kaplan-Meier analysis showed that the BFB increased survival. In the DMBA group, tumors showed invasive carcinoma of grade III with central necrosis, polymorphism, mitotic activity, and numerous newly formed ductules, and colloidal mucinous secretions within adenoid cysts. BFB administration restored the normal structure of the mammary glands.

CONCLUSION

Taken together, BFB has antitumor, pro-apoptotic, and anti-metastatic activities against breast cancer in mice and therefore, it merits further investigations.

Novel Azine Linked Hybrids of 2-Indolinone and Thiazolodinone Scaffolds as CDK2 Inhibitors with Potential Anticancer Activity: In Silico Design, Synthesis, Biological, Molecular Dynamics and Binding Free Energy Studies

Molecular hybrid of 2-indolinone-thiazolidinone is a well known scaffold for variable biological activities including anticancer activity. Accordingly, in the current work aided with structure-based molecular modeling studies, a library of novel twenty-six hybrids, 4(a-z), was designed and synthesized. Docking studies in the active site of CDK2, one of the key checkpoints enzymes, revealed that the binding scores of the designed molecules are comparable to the reference enzyme's inhibitors Sunitinib, Nintedanib, and Semaxanib. Variable antiproliferative activities are shown for these molecules against human liver (HepG2), breast (MCF7), and colon (HCT-29) cell lines considering Doxrubacin as a refrence drug. Compared to cytotoxic activities on the normal fibroblasts (WI-38), the tested molecules had better selectivity against the cancerous cells, expressed by their selectivity index (SI), than Doxrubacin and compound 4i was the safest compound. CDK2 inhibitory results of compounds 4f, 4g, 4h, and 4w showed IC50 at 59.43, 143.6, 27.42, and 61.63 nM respectively, while that of Sunitinib was 23.8 nM. To clarify the obtained biological activities of these molecules, broad docking and molecular dynamic simulations studies were undertaken and confirmed the consistency between the computational and the in vitro CDK2 inhibitory activities. Furthermore, in silico ADME/Tox profiles were done for the most active molecules using SwissADME and pkCSM-pharmacokinetics web-based methods predicted good pharmacokinetics, bioavailability, and toxicity profiles for the tested compounds.

Synthesis of new thienylnicotinamidines: Proapoptotic profile and cell cycle arrest of HepG2 cells

Fourteen new thienylnicotinamidines and their analogs 5a-5k, 12, 13a, and 13b were prepared and their antiproliferative potential was evaluated against the growth of 60 cancer cell lines. The tested compounds had a strong antiproliferative efficacy against almost all cancer cell lines, with the average GI50 at ~2.20 µM. The effect of the thienylnicotinamidines on the growth of normal lung fibroblast cells (WI-38) indicated that these derivatives are safe to the normal cells. The selectivity index (SI) ranges from 5.5- to 42.0-fold. The conceivable mechanisms of action of the effective compounds 5d, 5f, 5g, 5i, 5j, and 5k with high SI were investigated. Although the thienylnicotinamidines are similar in structure, they could be divided into three groups as per their effects on gene expression: The first group (5d and 5f) elevated p53 and caspase 3 expression, the second group (5g and 5i) elevated p53 expression, and the last group (5j and 5k) elevated p53 and reduced topoII expression. Many thienylnicotinamides inhibited the vascular endothelial growth factor receptor-2 (VEGFR-2) in cell lysates at concentrations comparable to or better than pazopanib. The data of caspase 3 expression were confirmed by measuring the protein level by Western blot and the activity of the cleaved active enzyme. The ability to arrest the cell cycle and induce apoptosis was confirmed by flow cytometry. Taken together, two derivatives, 5d and 5f, with a distinctive VEGFR-2 inhibitory activity and a proapoptotic and cell cycle arrest profile merit further investigations.

Small-Molecule Gankyrin Inhibition as a Therapeutic Strategy for Breast and Lung Cancer

Gankyrin is an oncoprotein responsible for the development of numerous cancer types. It regulates the expression levels of multiple tumor suppressor proteins (TSPs) in liver cancer; however, gankyrin's regulation of these TSPs in breast and lung cancers has not been thoroughly investigated. Additionally, no small-molecule gankyrin inhibitor has been developed which demonstrates potent anti-proliferative activity against gankyrin overexpressing breast and lung cancers. Herein, we are reporting the structure-based design of gankyrin-binding small molecules which potently inhibited the proliferation of gankyrin overexpressing A549 and MDA-MB-231 cancer cells, reduced colony formation, and inhibited the growth of 3D spheroids in an in vitro tumor simulation model. Investigations demonstrated that gankyrin inhibition occurs through either stabilization or destabilization of its 3D structure. These studies shed light on the mechanism of small-molecule inhibition of gankyrin and demonstrate that gankyrin is a viable therapeutic target for the treatment of breast and lung cancer.

Cancer Metabolism: The Role of Immune Cells Epigenetic Alteration in Tumorigenesis, Progression, and Metastasis of Glioma

Glioma is a type of brain and spinal cord tumor that begins in glial cells that support the nervous system neurons functions. Age, radiation exposure, and family background of glioma constitute are risk factors of glioma initiation. Gliomas are categorized on a scale of four grades according to their growth rate. Grades one and two grow slowly, while grades three and four grow faster. Glioblastoma is a grade four gliomas and the deadliest due to its aggressive nature (accelerated proliferation, invasion, and migration). As such, multiple therapeutic approaches are required to improve treatment outcomes. Recently, studies have implicated the significant roles of immune cells in tumorigenesis and the progression of glioma. The energy demands of gliomas alter their microenvironment quality, thereby inducing heterogeneity and plasticity change of stromal and immune cells via the PI3K/AKT/mTOR pathway, which ultimately results in epigenetic modifications that facilitates tumor growth. PI3K is utilized by many intracellular signaling pathways ensuring the proper functioning of the cell. The activation of PI3K/AKT/mTOR regulates the plasma membrane activities, contributing to the phosphorylation reaction necessary for transcription factors activities and oncogenes hyperactivation. The pleiotropic nature of PI3K/AKT/mTOR makes its activity unpredictable during altered cellular functions. Modification of cancer cell microenvironment affects many cell types, including immune cells that are the frontline cells involved in inflammatory cascades caused by cancer cells via high cytokines synthesis. Typically, the evasion of immunosurveillance by gliomas and their resistance to treatment has been attributed to epigenetic reprogramming of immune cells in the tumor microenvironment, which results from cancer metabolism. Hence, it is speculative that impeding cancer metabolism and/or circumventing the epigenetic alteration of immune cell functions in the tumor microenvironment might enhance treatment outcomes. Herein, from an oncological and immunological perspective, this review discusses the underlying pathomechanism of cell-cell interactions enhancing glioma initiation and metabolism activation and tumor microenvironment changes that affect epigenetic modifications in immune cells. Finally, prospects for therapeutic intervention were highlighted.

A translation control module coordinates germline stem cell differentiation with ribosome biogenesis during Drosophila oogenesis

Ribosomal defects perturb stem cell differentiation, and this is the cause of ribosomopathies. How ribosome levels control stem cell differentiation is not fully known. Here, we discover that three DExD/H-box proteins govern ribosome biogenesis (RiBi) and Drosophila oogenesis. Loss of these DExD/H-box proteins, which we name Aramis, Athos, and Porthos, aberrantly stabilizes p53, arrests the cell cycle, and stalls germline stem cell (GSC) differentiation. Aramis controls cell-cycle progression by regulating translation of mRNAs that contain a terminal oligo pyrimidine (TOP) motif in their 5' UTRs. We find that TOP motifs confer sensitivity to ribosome levels that are mediated by La-related protein (Larp). One such TOP-containing mRNA codes for novel nucleolar protein 1 (Non1), a conserved p53 destabilizing protein. Upon a sufficient ribosome concentration, Non1 is expressed, and it promotes GSC cell-cycle progression via p53 degradation. Thus, a previously unappreciated TOP motif in Drosophila responds to reduced RiBi to co-regulate the translation of ribosomal proteins and a p53 repressor, coupling RiBi to GSC differentiation.

Hyperglycaemia-induced human hepatocellular carcinoma (HepG2) cell proliferation through ROS-mediated P38 activation is effectively inhibited by a xanthophyll carotenoid, lutein

AIMS

Diabetic population have a twofold to threefold increased risk of developing liver cancer, and hyperglycaemia is a prime causative factor that propends the tumour cells to undergo aggressive metabolic growth. In this study, we aimed to examine the molecular mechanism by which lutein inhibits hyperglycaemia-induced human hepatocarcinoma (HepG2) cell proliferation.

METHODS

The effect of lutein on high glucose-induced proliferation was measured using the WST-1 reagent. Its effect on intracellular reactive oxygen species (ROS) levels was measured by DCF assay. The effect on the expression of antioxidant enzymes, cell cycle regulatory proteins and intracellular protein kinases was analysed by western blotting. The modulatory effect of lutein on different phases of the cell cycle was analysed by flow cytometry.

RESULTS

The data showed that lutein at 5 µM concentration significantly blocked glucose-promoted HepG2 cell proliferation. Suppression of high glucose-induced cell proliferation by lutein was not associated with apoptosis induction, but it was linked with inhibition of hyperglycaemia-mediated elevated ROS and upregulated expression of high glucose-mediated repressed heme oxygenase 1 (HO1). Furthermore, G2/M phase cell cycle arrest and associated phosphorylation of Cdk1 and P53 were found to be linked with suppressed hyperglycaemia-mediated cell proliferation by lutein. In addition, lutein inhibited hyperglycaemia-induced activation of P38 which relates to high glucose-induced ROS-mediated growth suppression and modulated the phosphorylation of Erk, JNK and Akt in hyperglycaemic HepG2 cells.

CONCLUSION

Our findings portray that sufficient intake of lutein may offer a negative impact on diabetes-associated tumour growth.

Synthesis, Antiproliferative Activity, and Apoptotic Profile of New Derivatives from the Meta Stable Benzoxazinone Scaffold

BACKGROUND

Cancer exerts a huge strain on the health system. The emerging resistance to the current chemotherapies demands the continuous development of new anticancer agents with lower cost, higher efficacy, and greater specificity.

OBJECTIVE

This study aimed at developing selective small molecules as targeted anticancer agents.

METHODS

The behavior of benzoxazinone 2 towards nitrogen nucleophiles, such as hydrazine hydrate, formamide, ethanolamine, aromatic amines, and thiosemicarbazide, was described. The behavior of the amino quinazolinone 3 towards carbon electrophiles and P2S5 was also investigated. The antiproliferative activity of 17 new benzoxazinone derivatives was examined against the growth of three human cancer cell lines; liver HepG2, breast MCF-7, and colon HCT-29, in addition to the normal human fibroblasts WI-38, and the selectivity index was calculated. The possible molecular pathways, such as the cell cycle and apoptosis, were investigated.

RESULTS

Derivatives 3, 7, 8, 10, 13, and 15 had a significant (less than 10 μM) antiproliferative activity against the three cancer cell lines investigated. Derivative 7 showed the best antiproliferative profile comparable to that of doxorubicin. The selectivity index for all the effective derivatives ranged from ~5-12 folds, indicating high selectivity against the cancer cells. Derivative 15 caused ~ 7-fold and 8-fold inductions in the expression of p53 and caspase3, respectively. It also caused a ~ 60% reduction in the expression of both topoisomerase II (topoII) and cyclin-dependent kinase 1 (cdk1). Derivatives 3, 7, and 8 had a similar profile; ~ 6-8-fold increased in the expression of p53 and caspase3 but these compounds were devoid of any significant effect on the expression of topoII and cdk1. Derivatives 10 and 13 were also similar and resulted in a ~6-fold elevation in the expression ofcaspase3, and more than 60% downregulation in the expression of topoII. The results of the gene expression of topoII and caspase3 were confirmed by the measurement of the topoII concentration and caspase3 activity in the HepG2 cells.

CONCLUSION

Six derivatives exerted their antiproliferative activity by arresting the cell cycle (decreasing cdk1), preventing the DNA duplication (downregulating topo II), and inducing apoptosis (inducing p53 and caspase3). One common feature in all the six active derivatives is the presence of a free amino group. These compounds have merit for further investigations.

Evaluation of the cytotoxic anticancer effect of polysaccharide of Nepeta septemcrenata

Background

Promoting cancer cells apoptosis is one of the effective methods to treat cancer. Human hepatocellular carcinoma (HepG2) and colorectal cancer (HCT-116) cell lines were used in the present study to evaluate the cytotoxic and anticancer properties of Nepeta septemcrenata Polysaccharide (NSP).

Result

Treatment of the two examined cells with NSP displayed a significant cytotoxicity towards HepG2 in a dose-dependent manner; meanwhile, its effect on HCT-116 was obtained under the influence of low doses. The quantitative real- time PCR (QRT-PCR) investigation revealed that NSP significantly up-regulated the expression levels of p53, p16, Fas, Fas-L, Bax, caspases-3, caspase-9, and TNF-α in association with down-regulation of cyclin D1, TERT, and BCL2. These findings declare the apoptotic characteristic of NSP.NSP, can also inhibit the development of cancer cells through the down-regulation of TGF-β and VEGF.

Conclusions

Our results suggested that the polysaccharides isolated from N. septemcrenata possess anticancer properties that could be explored for the development of novel anticancer agents.

Mechanism of Infantile Feire Kechuan Oral Solution against Mycoplasma pneumoniae infection of A549 cells

BACKGROUND

Mycoplasma pneumoniae is a leading cause of community-acquired respiratory infections. Infantile Feire Kechuan Oral Solution (IFKOS) is effective for treatment of M. pneumoniae infection. The aim of this study was to explore the potential mechanism of IFKOS against M. pneumoniae infection in basal epithelial human lung adenocarcinoma A549 cells.

METHODS

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the effects of IFKOS on the viability of A549 cells infected with M. pneumoniae. Optical microscopy was used to observe cell morphology and a Muse cell analyzer was used to assess apoptosis and the cell cycle phase. Enzyme-linked immunosorbent assays were employed to assess the expression levels of interleukin (IL)-4, IL-6, IL-8, IL-17, tumor necrosis factor (TNF)-α, interferon (IFN)-α, and IFN-γ.

RESULTS

Under certain conditions, M. pneumoniae infection reduced the viability and inhibited the proliferation of A549 cells, promoted early apoptosis, and arrested cells in the G0/G1 phase, thus shortening the S and G2/M phases (all p < 0.05). M. pneumoniae also upregulated expression of IL-8 and TNF-α and downregulated that of IL-6 (p < 0.05), which switched the immune balance of Th1/Th2 to Th1 cells. IFKOS (5.531 mg/mL) improved the viability and proliferation of M. pneumoniae-infected A549 cells, mitigated early apoptosis, and reversed cell cycle arrest in the G0/G1 phase, thereby extending the S and G2/M phases (all, p < 0.05). IFKOS downregulated expression of IL-8 and TNF-α and upregulated that of IL-6 (p < 0.01), thereby reversing the immune imbalance of Th1/Th2. Secretion of IL-4, IL-17, IFN-α, and IFN-γ was not observed.

CONCLUSION

IFKOS played a protective role in the regulation of cell viability, apoptosis, the cell cycle, and Th1/Th2 immune imbalance induced by M. pneumoniae infection and conveyed an anti-inflammatory effect in A549 cells.

Nobiletin, a hexamethoxyflavonoid from citrus pomace, attenuates G1 cell cycle arrest and apoptosis in hypoxia-induced human trophoblast cells of JEG-3 and BeWo via regulating the p53 signaling pathway

Background

Hypoxia is associated with abnormal cell apoptosis in trophoblast cells, which causes fetal growth restriction and related placental pathologies. Few effective methods for the prevention and treatment of placenta-related diseases exist. Natural products and functional foods have always been a rich source of potential anti-apoptotic drugs. Nobiletin (NOB), a hexamethoxyflavonoid derived from the citrus pomace, shows an anti-apoptotic activity, which is a non-toxic constituent of dietary phytochemicals approved by the Food and Drug Administration. However, their effects on hypoxia-induced human trophoblast cells have not been fully studied.

Objective

The aim of this study was to investigate the protective effects of NOB on hypoxia-induced apoptosis of human trophoblast JEG-3 and BeWo cells, and their underlying mechanisms.

Design

First, the protective effect of NOB on hypoxia-induced apoptosis of JEG-3 and BeWo cells was studied. Cell viability and membrane integrity were determined by CCK-8 assay and lactate dehydrogenase activity, respectively. Real Time Quantitative PCR (RT-qPCR) and Western blot analysis were used to detect the mRNA and protein levels of HIF1α. Propidium iodide (PI)-labeled flow cytometry was used to detect cell cycle distribution. Cell apoptosis was detected by flow cytometry with Annexin V-FITC and PI double staining, and the expression of apoptosis marker protein cl-PARP was detected by Western blot analysis. Then, the molecular mechanism of NOB against apoptosis was investigated. Computer molecular docking and dynamics were used to simulate the interaction between NOB and p53 protein, and this interaction was verified in vitro by Ultraviolet and visible spectrum (UV-visible spectroscopy), fluorescence spectroscopy and circular dichroism. Furthermore, the changes in the expression of p53 signaling pathway genes and proteins were detected by RT-qPCR and Western blot analysis, respectively.

Results

Hypoxia treatment resulted in a decreased cell viability and cell membrane integrity in JEG-3 and BeWo cell lines, and an increased expression of HIF1α, cell cycle arrest in the G1 phase, and massive cell apoptosis, which were alleviated after NOB treatment. Molecular docking and dynamics simulations found that NOB spontaneously bonded to human p53 protein, leading to the change of protein conformation. The intermolecular interaction between NOB and human p53 protein was further confirmed by UV-visible spectroscopy, fluorescence spectroscopy and circular dichroism. After the treatment of 100 μM NOB, a down-regulation of mRNA and protein levels of p53 and p21 and an up-regulation of BCL2/BAX mRNA and protein ratio were observed in JEG-3 cells; however, there was also a down-regulation of mRNA and protein levels observed for p53 and p21 in BeWo cells after the treatment of NOB. The BCL2/BAX ratio of BeWo cells did not change after the treatment of 100 μM NOB.

Conclusion

NOB attenuated hypoxia-induced apoptosis in JEG-3 and BeWo cell lines and might be a potential functional ingredient to prevent pregnancy-related diseases caused by hypoxia-induced apoptosis. These findings would also suggest the exploration and utilization of citrus resources, and the development of citrus industry.

The fellowship of the RING: BRCA1, its partner BARD1 and their liaison in DNA repair and cancer

The breast cancer type 1 susceptibility protein (BRCA1) and its partner - the BRCA1-associated RING domain protein 1 (BARD1) - are key players in a plethora of fundamental biological functions including, among others, DNA repair, replication fork protection, cell cycle progression, telomere maintenance, chromatin remodeling, apoptosis and tumor suppression. However, mutations in their encoding genes transform them into dangerous threats, and substantially increase the risk of developing cancer and other malignancies during the lifetime of the affected individuals. Understanding how BRCA1 and BARD1 perform their biological activities therefore not only provides a powerful mean to prevent such fatal occurrences but can also pave the way to the development of new targeted therapeutics. Thus, through this review work we aim at presenting the major efforts focused on the functional characterization and structural insights of BRCA1 and BARD1, per se and in combination with all their principal mediators and regulators, and on the multifaceted roles these proteins play in the maintenance of human genome integrity.

Synthesis, Antiproliferative Activity, Apoptotic Profiling, and In‐silico ADME of New Thienylbenzamidine Derivatives

Twelve new thienylbenzamidines and their analogues 4 a–i, 7, and 12 a, b were synthesized and their anti‐proliferative activity was evaluated against 60 cancer cell lines. The tested compounds showed potent anticancer activity against most cancer cell lines with median growth inhibition (GI50)<2 μM. Leukemia and renal cancer cell lines were the most responsive. Compound 12 a was the most active exhibiting GI50, total growth inhibition (TGI), and median lethal concentration (LC50) at 1.65, 3.71, and 9.3 μM, respectively. The benzamidine derivatives exerted their anti‐proliferative activity without causing any toxicity in normal human lung fibroblast (WI‐38) cells. The selectivity index (SI) ranged from 5.6 to 59.0 fold. Compound 4 h was the most selective compound (SI=59), and it was the least cytotoxic to WI‐38 cells. The cationic compounds 4 c, 4 h, 4 i, 7, and 12 b with high SI were selected for further mechanistic studies. Compounds 4 c, 4 h, and 4 i exerted their antiproliferative activity by inducing the cell cycle arrest (elevated p53 and downregulated cyclin‐dependent kinase 1 (cdk1)) and inducing apoptosis (elevated caspase 3). Compounds 7 and 12 b exerted their activity by inhibiting the growth and proliferation of cancer cells through inhibiting both topoisomerase II (topoII) and thioredoxin reductase1 (txnrd1). Finally, in silico predictions of the physicochemical, pharmacokinetic and drug‐likeness profiles of these new derivatives proved the oral availability and the inability to cross the blood‐brain barrier.

Regulation of DNA damage response by trimeric G-protein Signaling.. [DOI: 10.1101/2021.07.21.452842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Upon sensing DNA double-strand breaks (DSBs), eukaryotic cells either die or repair DSBs via one of two competing pathways, i.e., non-homologous end-joining (NHEJ) or homologous recombination (HR). We show that cell fate after DNA damage hinges on the guanine nucleotide-exchange modulator of heterotrimeric G-protein, Giα•βγ, GIV/Girdin. GIV suppresses HR by binding and sequestering BRCA1, a key coordinator of multiple steps within the HR pathway, away from DSBs; it does so using a C-terminal motif that binds BRCA1’s BRCT-modules via both phospho-dependent and -independent mechanisms. GIV promotes NHEJ, and binds and activates Gi and enhances the ‘free’ Gβγ→PI-3-kinase→Akt pathway, thus revealing the enigmatic origin of prosurvival Akt signals during dsDNA repair. Absence of GIV, or the loss of either of its two functions impaired DNA repair, and induced cell death when challenged with numerous cytotoxic agents. That GIV selectively binds few other BRCT-containing proteins suggests convergent signaling such that heterotrimeric G-proteins may finetune sensing, repair, and outcome after DNA damage.

GRAPHIC ABSTRACT

HIGHLIGHTS

Non-receptor G protein modulator, GIV/Girdin binds BRCA1

Binding occurs in both canonical and non-canonical modes

GIV sequesters BRCA1 away from dsDNA breaks, suppresses HR

Activation of Gi by GIV enhances Akt signals, favors NHEJ

IN BRIEF

In this work, the authors show that heterotrimeric G protein signaling that is triggered by non-receptor GEF, GIV/Girdin, in response to double-stranded DNA breaks is critical for decisive signaling events which favor non-homologous end-joining (NHEJ) and inhibit homologous recombination (HR).

Long noncoding RNAs in the regulation of p53-mediated apoptosis in human cancers

Long noncoding RNAs (lncRNAs) are widely known for their regulatory function in transcriptional and posttranscriptional processes. The involvement of such non-protein-coding RNAs in nuclear organization and chromatin remodeling is often associated with an increased risk of human malignancies. In cancer, lncRNAs either promote cell survival or may act as a growth suppressor, thus conferring a key regulatory function other than their established role in fundamental cellular processes. Interestingly, lncRNAs interfere with the stages of apoptosis and related pathways involving p53. Many of these molecules either regulate or are regulated by p53 while mounting oncogenic events. Consequently, they may confer both prosurvival or proapoptotic functions depending upon the tissue type. Since the mechanism of cell death is bypassed in many human cancers, it has emerged that the lncRNAs are either overexpressed or knocked down to sensitize cells to apoptotic stimuli. Nonetheless, the abundant expression of lncRNAs in tumor cells renders them suitable targets for anticancer therapies. Although the role of lncRNAs in the p53 network and apoptosis has been independently defined, their interplay in activating p53-target genes during cell cycle arrest remains unexplored. Thus, we have specifically reviewed the possible involvement of lncRNAs in the p53-mediated apoptosis of human cancer cells. In particular, we summarize the growing evidence from individual studies and analyze whether lncRNAs are essential to facilitate apoptosis in a p53-dependent manner. This may lead to the identification of p53-associated lncRNAs that are suitable therapeutic targets or diagnostic/prognostic markers.

Differential effects of cisplatin combined with the flavonoid apigenin on HepG2, Hep3B, and Huh7 liver cancer cell lines

The potential of apigenin (APG) to enhance cisplatin's (CDDP) chemotherapeutic efficacy was investigated in HepG2, Hep3B, and Huh7 liver cancer cell lines. The presence of 20 μM APG sensitized all cell lines to CDDP treatment (degree of sensitization based on the MTT assay: HepG2>Huh7>Hep3B). As reflected by sister chromatid exchange levels, the degree of genetic instability as well as DNA repair by homologous recombination differed among cell lines. CDDP and 20 μM APG cotreatment exhibited a synergistic genotoxic effect on Hep3B cells and a less than additive effect on HepG2 and Huh7 cells. Cell cycle delays were noticed during the first mitotic division in Hep3B and Huh7 cells and the second mitotic division in HepG2 cells. CDDP and CDDP + APG treatments reduced the clonogenic capacity of all cell lines; however, there was a discordance in drug sensitivity compared with the MMT assay. Furthermore, a senescence-like phenotype was induced, especially in Hep3B and Huh7 cells. Unlike CDDP monotherapy, the combined treatment exhibited a significant anti-invasive and anti-migratory action in all cancer cell lines. The fact that the three liver cancer cell lines responded differently, yet positively, to CDDP + APG cotreatment could be attributed to variations they present in gene expression. Complex mechanisms seem to influence cellular responses and cell fate.

The Biological Significance of Targeting Acetylation-Mediated Gene Regulation for Designing New Mechanistic Tools and Potential Therapeutics

The molecular interplay between nucleosomal packaging and the chromatin landscape regulates the transcriptional programming and biological outcomes of downstream genes. An array of epigenetic modifications plays a pivotal role in shaping the chromatin architecture, which controls DNA access to the transcriptional machinery. Acetylation of the amino acid lysine is a widespread epigenetic modification that serves as a marker for gene activation, which intertwines the maintenance of cellular homeostasis and the regulation of signaling during stress. The biochemical horizon of acetylation ranges from orchestrating the stability and cellular localization of proteins that engage in the cell cycle to DNA repair and metabolism. Furthermore, lysine acetyltransferases (KATs) modulate the functions of transcription factors that govern cellular response to microbial infections, genotoxic stress, and inflammation. Due to their central role in many biological processes, mutations in KATs cause developmental and intellectual challenges and metabolic disorders. Despite the availability of tools for detecting acetylation, the mechanistic knowledge of acetylation-mediated cellular processes remains limited. This review aims to integrate molecular and structural bases of KAT functions, which would help design highly selective tools for understanding the biology of KATs toward developing new disease treatments.

DNA damage-how and why we age?

Aging is a complex process that results in loss of the ability to reattain homeostasis following stress, leading, thereby, to increased risk of morbidity and mortality. Many factors contribute to aging, such as the time-dependent accumulation of macromolecular damage, including DNA damage. The integrity of the nuclear genome is essential for cellular, tissue, and organismal health. DNA damage is a constant threat because nucleic acids are chemically unstable under physiological conditions and vulnerable to attack by endogenous and environmental factors. To combat this, all organisms possess highly conserved mechanisms to detect and repair DNA damage. Persistent DNA damage (genotoxic stress) triggers signaling cascades that drive cells into apoptosis or senescence to avoid replicating a damaged genome. The drawback is that these cancer avoidance mechanisms promote aging. Here, we review evidence that DNA damage plays a causal role in aging. We also provide evidence that genotoxic stress is linked to other cellular processes implicated as drivers of aging, including mitochondrial and metabolic dysfunction, altered proteostasis and inflammation. These links between damage to the genetic code and other pillars of aging support the notion that DNA damage could be the root of aging.

Epstein-Barr Virus-Oral Bacterial Link in the Development of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. Its development has been associated with diverse factors such as tobacco smoking and alcohol consumption. In addition, it has been suggested that microorganisms are risk factors for oral carcinogenesis. Epstein-Barr virus (EBV), which establishes lifelong persistent infections and is intermittently shed in the saliva, has been associated with several lymphomas and carcinomas that arise in the oral cavity. In particular, it has been detected in a subset of OSCCs. Moreover, its presence in patients with periodontitis has also been described. Porphyromonas gingivalis (P. gingivalis) is an oral bacterium in the development of periodontal diseases. As a keystone pathogen of periodontitis, P. gingivalis is known not only to damage local periodontal tissues but also to evade the host immune system and eventually affect systemic health. Persistent exposure to P. gingivalis promotes tumorigenic properties of oral epithelial cells, suggesting that chronic P. gingivalis infection is a potential risk factor for OSCC. Given that the oral cavity serves as the main site where EBV and P. gingivalis are harbored, and because of their oncogenic potential, we review here the current information about the participation of these microorganisms in oral carcinogenesis, describe the mechanisms by which EBV and P. gingivalis independently or synergistically can collaborate, and propose a model of interaction between both microorganisms.

AMG900 as novel inhibitor of the translationally controlled tumor protein

INTRODUCTION

Cancer is one of the leading causes of death worldwide. Classical cytotoxic chemotherapy exerts high side effects and low tumor selectivity. Translationally controlled tumor protein (TCTP) is a target for differentiation therapy, a promising, new therapeutic approach, which is expected to be more selective and less toxic than cytotoxic chemotherapy. The aim of the present investigation was to identify novel TCTP inhibitors.

METHODS

We performed in silico screening and molecular docking using a chemical library of more than 31,000 compounds to identify a novel inhibitor of TCTP. We tested AMG900 in vitro for binding to TCTP by microscale thermophoresis and co-immunoprecipitation. Additionally, we examined the effect of TCTP blockade on cell cycle progression by flow cytometry and Western blotting and cancer cell survival by resazurin assays in MCF-7, SK-OV3 and MOLT-4 cell lines.

RESULTS

We identified AMG900 as new inhibitor of TCTP. AMG900 bound to the p53 binding site of TCTP with a free binding energy of -9.63 ± 0.01 kcal/mol. This compound decreased TCTP expression to 23.4 ± 1.59% and increased p53 expression to 194.29 ± 24.27%. Furthermore, AMG900 induced G0/G1 arrest as shown by flow cytometry and Western blot of relevant cell cycle proteins. AMG900 decreased CDK2, CDK4, CDK6, cyclin D1 and cyclin D3 expression, whereas p18, p21 and p27 expression increased. Moreover, AMG900 disturbed TCTP-p53 complexation as shown by co-immunoprecipitation and increased expression of free p53.

DISCUSSION

AMG900 may serve as novel lead compound for the development of differentiation therapy approaches against cancer.

Thymidine kinase 1 through the ages: a comprehensive review

Proliferation markers, such as proliferating cell nuclear antigen (PCNA), Ki-67, and thymidine kinase 1 (TK1), have potential as diagnostic tools and as prognostic factors in assessing cancer treatment and disease progression. TK1 is involved in cellular proliferation through the recovery of the nucleotide thymidine in the DNA salvage pathway. TK1 upregulation has been found to be an early event in cancer development. In addition, serum levels of TK1 have been shown to be tied to cancer stage, so that higher levels of TK1 indicate a more serious prognosis. As a result of these findings and others, TK1 is not only a potentially viable biomarker for cancer recurrence, treatment monitoring, and survival, but is potentially more advantageous than current biomarkers. Compared to other proliferation markers, TK1 levels during S phase more accurately determine the rate of DNA synthesis in actively dividing tumors. Several reviews of TK1 elaborate on various assays that have been developed to measure levels in the serum of cancer patients in clinical settings. In this review, we include a brief history of important TK1 discoveries and findings, a comprehensive overview of TK1 regulation at DNA to protein levels, and recent findings that indicate TK1’s potential role in cancer pathogenesis and its growing potential as a tumor biomarker and therapeutic target.

Synthesis of new thienylpicolinamidine derivatives and possible mechanisms of antiproliferative activity

Three thienylpicolinamidine derivatives 4a-c were prepared from their corresponding picolinonitriles 3a-c on treatment with lithium trimethylsilylamide, LiN(TMS)2, followed by a de-protection step using ethanol/HCl (gas). DFT calculations were used to optimize the geometric structure of the newly synthesized picolinamidines. The comparison of DFT calculated spectral data with the experimental data (1H-NMR and 13C-NMR) showed a good agreement. The in vitro antiproliferative activity of the cationic compounds 4a-c was determined against 60 cancer cell lines representing nine types of cancer. The tested picolinamidines were highly active with compounds 4a and 4b eliciting mainly cytotoxic activity with GI values ranging from -7.17 to -86.03. Leukemia (SR and K-562), colon (SW-620 and HT29), and non-small cell lung cancer (NCI-H460) cell lines were the most responsive to the investigated picolinamidines. In particular, 4-methoxyphenyl derivative 4a showed a profound growth deterring power with GI50 of 0.34 μM against SR, 0.43 μM against SW-620, and 0.52 μM against NCI-H460. The three tested picolinamidines elicited potent GI50 values against all tested cell lines at low micromolar to sub-micromolar level. The new picolinamidines were selective and did not affect normal human fibroblasts. The selectivity index ranged from 13-21 μM. The novel picolinamidines downregulated the expression of key genes in the cell cycle, cdk1 and topoII, but did not affect p53 or txnrd1. Compounds 4b and 4c caused a significant reduction in the concentrations of TopoII and MAPK proteins but were devoid of any effect on the activity of caspase 3. Taken together, these promising anticancer candidates are effective at very low concentrations and safe to normal cells, and most probably work through arresting the cell cycle, and therefore, they deserve further investigations.