Emerging regulatory mechanisms and functions of biomolecular condensates: implications for therapeutic targets

Cells orchestrate their processes through complex interactions, precisely organizing biomolecules in space and time. Recent discoveries have highlighted the crucial role of biomolecular condensates-membrane-less assemblies formed through the condensation of proteins, nucleic acids, and other molecules-in driving efficient and dynamic cellular processes. These condensates are integral to various physiological functions, such as gene expression and intracellular signal transduction, enabling rapid and finely tuned cellular responses. Their ability to regulate cellular signaling pathways is particularly significant, as it requires a careful balance between flexibility and precision. Disruption of this balance can lead to pathological conditions, including neurodegenerative diseases, cancer, and viral infections. Consequently, biomolecular condensates have emerged as promising therapeutic targets, with the potential to offer novel approaches to disease treatment. In this review, we present the recent insights into the regulatory mechanisms by which biomolecular condensates influence intracellular signaling pathways, their roles in health and disease, and potential strategies for modulating condensate dynamics as a therapeutic approach. Understanding these emerging principles may provide valuable directions for developing effective treatments targeting the aberrant behavior of biomolecular condensates in various diseases.

Gene Editing with Artificial DNA Scissors

Artificial metallo-nucleases (AMNs) are small molecule DNA cleavage agents, also known as DNA molecular scissors, and represent an important class of chemotherapeutic with high clinical potential. This review provides a primary level of exploration on the concepts key to this area including an introduction to DNA structure, function, recognition, along with damage and repair mechanisms. Building on this foundation, we describe hybrid molecules where AMNs are covalently attached to directing groups that provide molecular scissors with enhanced or sequence specific DNA damaging capabilities. As this research field continues to evolve, understanding the applications of AMNs along with synthetic conjugation strategies can provide the basis for future innovations, particularly for designing new artificial gene editing systems.

A promising future of metal-N-heterocyclic carbene complexes in medicinal chemistry: The emerging bioorganometallic antitumor agents

Metal complexes based on N-heterocyclic carbene (NHC) ligands have emerged as promising broad-spectrum antitumor agents in bioorganometallic medicinal chemistry. In recent decades, studies on cytotoxic metal-NHC complexes have yielded numerous compounds exhibiting superior cytotoxicity compared to cisplatin. Although the molecular mechanisms of these anticancer complexes are not fully understood, some potential targets and modes of action have been identified. However, a comprehensive review of their biological mechanisms is currently absent. In general, apoptosis caused by metal-NHCs is common in tumor cells. They can cause a series of changes after entering cells, such as mitochondrial membrane potential (MMP) variation, reactive oxygen species (ROS) generation, cytochrome c (cyt c) release, endoplasmic reticulum (ER) stress, lysosome damage, and caspase activation, ultimately leading to apoptosis. Therefore, a detailed understanding of the influence of metal-NHCs on cancer cell apoptosis is crucial. In this review, we provide a comprehensive summary of recent advances in metal-NHC complexes that trigger apoptotic cell death via different apoptosis-related targets or signaling pathways, including B-cell lymphoma 2 (Bcl-2 family), p53, cyt c, ER stress, lysosome damage, thioredoxin reductase (TrxR) inhibition, and so forth. We also discuss the challenges, limitations, and future directions of metal-NHC complexes to elucidate their emerging application in medicinal chemistry.

The influence of a modified p53 C-terminal peptide by using a tumor-targeting sequence on cellular apoptosis and tumor treatment

The restoration of the function of p53 in tumors is a therapeutic strategy for the highly frequent mutation of the TP53 tumor suppressor gene. P460 is a wild-type peptide derived from the p53 C-terminus and has been proven to be capable of restoring the tumor suppressor function of p53. The poor accumulation of drugs in tumors is a serious hindrance to tumor treatment. For enhancing the activity of P460, the tumor-targeting sequence Arg-Gly-Asp-Arg (RGDR, C-end rule peptide) was introduced into the C-terminus of P460 to generate the new peptide P462. P462 presented better activity than P460 in inhibiting the proliferation of cancer cells and increasing the number of tumor cells undergoing apoptosis. Cell adhesion analysis and tumor imaging results revealed that P462 showed more specific and extensive binding with tumor cells and greater accumulation in tumors than the wild-type peptide. Importantly, treatment with P462 was more efficacious than that with P460 in vivo and was associated with considerably improved tumor-homing activity. This study highlights the importance of the roles of the tumor-homing sequence RGDR in the enhancement in cell attachment and tumor accumulation. The results of this work indicate that P462 could be a novel drug candidate for tumor treatment.

Targeting misfolding and aggregation of the amyloid-β peptide and mutant p53 protein using multifunctional molecules

Biomolecule misfolding and aggregation play a major role in human disease, spanning from neurodegeneration to cancer. Inhibition of these processes is of considerable interest, and due to the multifactorial nature of these diseases, the development of drugs that act on multiple pathways simultaneously is a promising approach. This Feature Article focuses on the development of multifunctional molecules designed to inhibit the misfolding and aggregation of the amyloid-β (Aβ) peptide in Alzheimer's disease (AD), and the mutant p53 protein in cancer. While for the former, the goal is to accelerate the removal of the Aβ peptide and associated aggregates, for the latter, the goal is reactivation via stabilization of the active folded form of mutant p53 protein and/or aggregation inhibition. Due to the similar aggregation pathway of the Aβ peptide and mutant p53 protein, a common therapeutic approach may be applicable.

Altering relative metal-binding affinities in multifunctional Metallochaperones for mutant p53 reactivation

The p53 protein plays a major role in cancer prevention, and over 50% of cancer diagnoses can be attributed to p53 malfunction. p53 incorporates a structural Zn site that is required for proper protein folding and function, and in many cases point mutations can result in loss of the Zn2+ ion, destabilization of the tertiary structure, and eventual amyloid aggregation. Herein, we report a series of compounds designed to act as small molecule stabilizers of mutant p53, and feature Zn-binding fragments to chaperone Zn2+ to the metal depleted site and restore wild-type (WT) function. Many Zn metallochaperones (ZMCs) have been shown to generate intracellular reactive oxygen species (ROS), likely by chelating redox-active metals such as Fe2+/3+ and Cu+/2+ and undergoing associated Fenton chemistry. High levels of ROS can result in off-target effects and general toxicity, and thus, careful tuning of ligand Zn2+ affinity, in comparison to the affinity for other endogenous metals, is important for selective mutant p53 targeting. In this work we show that by using carboxylate donors in place of pyridine we can change the relative Zn2+/Cu2+ binding ability in a series of ligands, and we investigate the impact of donor group changes on metallochaperone activity and overall cytotoxicity in two mutant p53 cancer cell lines (NUGC3 and SKGT2).

Targeting p53 misfolding conundrum by stabilizing agents and their analogs in breast cancer therapy: a comprehensive computational analysis

Cancer continues to be a major global public health concern and one of the foremost causes of death. Delays in the diagnosis and cure may cause an increase in advanced stage disease and mortality. The most common cancer found in women currently is breast carcinoma. Breast carcinoma has surpassed lung carcinoma and currently represents the chief type of cancer diagnosed (2.3 million new cases, which amount to 11.7% of all cancer cases). In addition, by 2040, the incidence will increase by more than 46% as per the estimates of GLOBOCAN. Triple-negative breast cancer (TNBC) represents a highly aggressive and invasive subtype of breast cancer, characterized by rapid progression, short response time to the available treatment, and poor clinical results. Thus, it is very crucial to develop novel diagnostic tools and therapeutics with good efficacy. A majority of cancers display malfunction along the p53 pathway. Moreover, p53 not only loses its function but is also prone to misfolding and aggregation, leading to formation of amyloid aggregates as well. Research is being carried out to find ways to restore the normal action and expression of p53. Here, we have explored PhiKan-083 for its possible stabilizing effect on p53 in order to address the problem with its misfolding. Thus, examining the analogs of PhiKan-083 that have a role in p53 stability will help update our understanding of cancer progression and may expedite the progress of new anticancer treatments. We anticipate that the drug molecules and their analogs targeting p53 aggregation may be used in combination with other anticancer compounds to solve the problem with p53 aggregation. In this study, by employing ADMET analysis, the compounds were screened, and we further examined the chosen compounds with the help of molecular docking. By using databases like UALCAN, TIMER, GEPIA, and PredictProtein, we investigated TP53's expression pattern and prognostic relevance in various cancer settings.

A novel ΔNp63-dependent immune mechanism improves prognosis of HPV-related head and neck cancer

Background

Deconvoluting the heterogenous prognosis of Human Papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OSCC) is crucial for enhancing patient care, given its rapidly increasing incidence in western countries and the adverse side effects of OSCC treatments.

Methods

Transcriptomic data from HPV-positive OSCC samples were analyzed using unsupervised hierarchical clustering, and clinical relevance was evaluated using Kaplan-Meier analysis. HPV-positive OSCC cell line models were used in functional analyses and phenotypic assays to assess cell migration and invasion, response to cisplatin, and phagocytosis by macrophages in vitro.

Results

We found, by transcriptomic analysis of HPV-positive OSCC samples, a ΔNp63 dependent molecular signature that is associated with patient prognosis. ΔNp63 was found to act as a tumor suppressor in HPV-positive OSCC at multiple levels. It inhibits cell migration and invasion, and favors response to chemotherapy. RNA-Seq analysis uncovered an unexpected regulation of genes, such as DKK3, which are involved in immune response-signalling pathways. In agreement with these observations, we found that ΔNp63 expression levels correlate with an enhanced anti-tumor immune environment in OSCC, and ΔNp63 promotes cancer cell phagocytosis by macrophages through a DKK3/NF-κB-dependent pathway.

Conclusion

Our findings are the first comprehensive identification of molecular mechanisms involved in the heterogeneous prognosis of HPV-positive OSCC, paving the way for much-needed biomarkers and targeted treatment.

A functional nucleic acid-based fluorescence sensing platform based on DNA supersandwich nanowires and cation exchange reaction

Accurate and sensitive analysis of p53 DNA is important for early diagnosis of cancer. In this work, a fluorescence sensing system based on DNA supersandwich nanowires and cation exchange (CX)-triggered multiplex signal amplification was constructed for the detection of p53 DNA. In the presence of p53 DNA, the DNA self-assembles to form a DNA supersandwich nanowire that generates long double-stranded DNA. Subsequently, the cation exchange (CX) reaction between ZnS and Ag+ was utilized to release free Zn2+. With the participation of Zn2+, DNAzyme catalyzes the hydrolysis of numerous catalytic molecular beacons, resulting in a greatly enhanced fluorescence signal due to the cycling of DNAzyme. The fluorescence values increased in proportion to the concentrations of p53 DNA in the range of 10 pM to 200 nM, and a detection limit (LOD) of 2.34 pM (S/N = 3) was obtained. This method provides an effective strategy for the quantitative detection of p53 DNA.

Targeting Biomolecular Condensation and Protein Aggregation against Cancer

Biomolecular condensates, membrane-less entities arising from liquid-liquid phase separation, hold dichotomous roles in health and disease. Alongside their physiological functions, these condensates can transition to a solid phase, producing amyloid-like structures implicated in degenerative diseases and cancer. This review thoroughly examines the dual nature of biomolecular condensates, spotlighting their role in cancer, particularly concerning the p53 tumor suppressor. Given that over half of the malignant tumors possess mutations in the TP53 gene, this topic carries profound implications for future cancer treatment strategies. Notably, p53 not only misfolds but also forms biomolecular condensates and aggregates analogous to other protein-based amyloids, thus significantly influencing cancer progression through loss-of-function, negative dominance, and gain-of-function pathways. The exact molecular mechanisms underpinning the gain-of-function in mutant p53 remain elusive. However, cofactors like nucleic acids and glycosaminoglycans are known to be critical players in this intersection between diseases. Importantly, we reveal that molecules capable of inhibiting mutant p53 aggregation can curtail tumor proliferation and migration. Hence, targeting phase transitions to solid-like amorphous and amyloid-like states of mutant p53 offers a promising direction for innovative cancer diagnostics and therapeutics.

Multifunctional metallochaperone modifications for targeting subsite cavities in mutant p53-Y220C

The p53 protein, known as the 'guardian of the genome', plays an important role in cancer prevention. Unfortunately, p53 mutations result in compromised activity with over 50% of cancers resulting from point mutations to p53. There is considerable interest in mutant p53 reactivation, with the development of small-molecule reactivators showing promise. We have focused our efforts on the common p53 mutation Y220C, which causes protein unfolding, aggregation, and can result in the loss of a structural Zn from the DNA-binding domain. In addition, the Y220C mutant creates a surface pocket that can be stabilized using small molecules. We previously reported the bifunctional ligand L5 as a Zn metallochaperone and reactivator of the p53-Y220C mutant. Herein we report two new ligands L5-P and L5-O that are designed to act as Zn metallochaperones and non-covalent binders in the Y220C mutant pocket. For L5-P the distance between the Zn-binding di-(2-picolyl)amine function and the pocket-binding diiodophenol was extended in comparison to L5, while for L5-O we extended the pocket-binding moiety via attachment of an alkyne function. While both new ligands displayed similar Zn-binding affinity to L5, neither acted as efficient Zn-metallochaperones. However, the new ligands exhibited significant cytotoxicity in the NCI-60 cell line screen as well as in the NUGC3 Y220C mutant cell line. We identified that the primary mode of cytotoxicity is likely reactive oxygen species (ROS) generation for L5-P and L5-O, in comparison to mutant p53 reactivation for L5, demonstrating that subtle changes to the ligand scaffold can change the toxicity pathway.

Reduced Levels of Misfolded and Aggregated Mutant p53 by Proteostatic Activation

In malignant cancer, excessive amounts of mutant p53 often lead to its aggregation, a feature that was recently identified as druggable. Here, we describe that induction of a heat shock-related stress response mediated by Foldlin, a small-molecule tool compound, reduces the protein levels of misfolded/aggregated mutant p53, while contact mutants or wild-type p53 remain largely unaffected. Foldlin also prevented the formation of stress-induced p53 nuclear inclusion bodies. Despite our inability to identify a specific molecular target, Foldlin also reduced protein levels of aggregating SOD1 variants. Finally, by screening a library of 778 FDA-approved compounds for their ability to reduce misfolded mutant p53, we identified the proteasome inhibitor Bortezomib with similar cellular effects as Foldlin. Overall, the induction of a cellular heat shock response seems to be an effective strategy to deal with pathological protein aggregation. It remains to be seen however, how this strategy can be translated to a clinical setting.

Targeting p53 pathways: mechanisms, structures, and advances in therapy

The TP53 tumor suppressor is the most frequently altered gene in human cancers, and has been a major focus of oncology research. The p53 protein is a transcription factor that can activate the expression of multiple target genes and plays critical roles in regulating cell cycle, apoptosis, and genomic stability, and is widely regarded as the "guardian of the genome". Accumulating evidence has shown that p53 also regulates cell metabolism, ferroptosis, tumor microenvironment, autophagy and so on, all of which contribute to tumor suppression. Mutations in TP53 not only impair its tumor suppressor function, but also confer oncogenic properties to p53 mutants. Since p53 is mutated and inactivated in most malignant tumors, it has been a very attractive target for developing new anti-cancer drugs. However, until recently, p53 was considered an "undruggable" target and little progress has been made with p53-targeted therapies. Here, we provide a systematic review of the diverse molecular mechanisms of the p53 signaling pathway and how TP53 mutations impact tumor progression. We also discuss key structural features of the p53 protein and its inactivation by oncogenic mutations. In addition, we review the efforts that have been made in p53-targeted therapies, and discuss the challenges that have been encountered in clinical development.

Inhibition of p53 protein aggregation as a cancer treatment strategy

The p53 protein plays a critical role in the prevention of genome mutations in the body, however, this protein is frequently mutated in cancer and almost all cancers exhibit malfunction along the p53 pathway. In addition to a loss of activity, mutant p53 protein is prone to unfolding and aggregation, eventually forming amyloid aggregates. There continues to be a considerable effort to develop strategies to restore normal p53 expression and activity and this review details recent advances in small-molecule stabilization of mutant p53 protein and the design of p53 aggregation inhibitors.

Identification of 3-Phenylquinoline Derivative PQ1 as an Antagonist of p53 Transcriptional Activity

Transcription factor p53 regulates cellular responses to environmental perturbations via the transcriptional activation of downstream target genes. Inappropriate p53 activation can trigger abnormal cellular responses, therefore leading to acute or chronic tissue damage, human developmental syndromes, and neurodegenerative diseases. Antagonists of p53 transcriptional activity provide prospective therapeutic applications and molecular probes. In this article, we identified five 3-phenylquinoline derivatives as potential p53 inhibitors through screening a chemical library consisting of 120 compounds, in which PQ1 was the most active compound. PQ1 had no effect on p53 protein levels and decreased the expression of p53 target gene p21. PQ1 thermally stabilizes the wild-type p53 protein. Further, transcriptomics confirmed that PQ1 exposure generated a similar regulatory effect to transcription profiles with a reported p53 transcriptional inhibitor pifithrin-α. However, compared to pifithrin-α, PQ1 increased the sensitivity of SW480 cells to 5FU. Taken together, PQ1 was a novel antagonist of p53 transcriptional activity. We propose that PQ1 could be developed as a chemical tool to pinpoint the physiological functions of p53 and a novel lead compound for targeting dysfunctional p53 activation.

The EXTREME Regimen Associating Cetuximab and Cisplatin Favors Head and Neck Cancer Cell Death and Immunogenicity with the Induction of an Anti-Cancer Immune Response

(1) Background: The first line of treatment for recurrent/metastatic Head and Neck Squamous Cell Carcinoma (HNSCC) has recently evolved with the approval of immunotherapies that target the anti-PD-1 immune checkpoint. However, only about 20% of the patients display a long-lasting objective tumor response. The modulation of cancer cell immunogenicity via a treatment-induced immunogenic cell death is proposed to potentially be able to improve the rate of patients who respond to immune checkpoint blocking immunotherapies. (2) Methods: Using human HNSCC cell line models and a mouse oral cancer syngeneic model, we have analyzed the ability of the EXTREME regimen (combination therapy using the anti-EGFR cetuximab antibody and platinum-based chemotherapy) to modify the immunogenicity of HNSCC cells. (3) Results: We showed that the combination of cetuximab and cisplatin reduces cell growth through both cell cycle inhibition and the induction of apoptotic cell death independently of p53. In addition, different components of the EXTREME regimen were found to induce, to a variable extent, and in a cell-dependent manner, the emission of mediators of immunogenic cell death, including calreticulin, HMGB1, and type I Interferon-responsive chemokines. Interestingly, cetuximab alone or combined with the IC₅₀ dose of cisplatin can induce an antitumor immune response in vivo, but not when combined with a high dose of cisplatin. (4) Conclusions: Our observations suggest that the EXTREME protocol or cetuximab alone are capable, under conditions of moderate apoptosis induction, of eliciting the mobilization of the immune system and an anti-tumor immune response in HNSCC.

Discovery of spirooxindole-derived small-molecule compounds as novel HDAC/MDM2 dual inhibitors and investigation of their anticancer activity

Simultaneous inhibition of more than one target is considered to be a novel strategy in cancer therapy. Owing to the importance of histone deacetylases (HDACs) and p53-murine double minute 2 (MDM2) interaction in tumor development and their synergistic effects, a series of MDM2/HDAC bifunctional small-molecule inhibitors were rationally designed and synthesized by incorporating an HDAC pharmacophore into spirooxindole skeletons. These compounds exhibited good inhibitory activities against both targets. In particular, compound 11b was demonstrated to be most potent for MDM2 and HDAC, reaching the enzyme inhibition of 68% and 79%, respectively. Compound 11b also showed efficient antiproliferative activity towards MCF-7 cells with better potency than the reference drug SAHA and Nutlin-3. Furthermore, western blot analysis revealed that compound 11b increased the expression of p53 and Ac-H4 in MCF-7 cells in a dose-dependent manner. Our results indicate that dual inhibition of HDAC and MDM2 may provide a novel and efficient strategy for the discovery of antitumor drug in the future.

A role for bioinorganic chemistry in the reactivation of mutant p53 in cancer

Metal ion dysregulation has been implicated in a number of diseases from neurodegeneration to cancer. While defective metal ion transport mechanisms are known to cause specific diseases of genetic origin, the role of metal dysregulation in many diseases has yet to be elucidated due to the complicated function (both good and bad!) of metal ions in the body. A breakdown in metal ion speciation can manifest in several ways from increased reactive oxygen species (ROS) generation to an increase in protein misfolding and aggregation. In this review, we will discuss the role of Zn in the proper function of the p53 protein in cancer. The p53 protein plays a critical role in the prevention of genome mutations via initiation of apoptosis, DNA repair, cell cycle arrest, anti-angiogenesis, and senescence pathways to avoid propagation of damaged cells. p53 is the most frequently mutated protein in cancer and almost all cancers exhibit malfunction along the p53 pathway. Thus, there has been considerable effort dedicated to restoring normal p53 expression and activity to mutant p53. This includes understanding the relative populations of the Zn-bound and Zn-free p53 in wild-type and mutant forms, and the development of metallochaperones to re-populate the Zn binding site to restore mutant p53 activity. Parallels will be made to the development of multifunctional metal binding agents for modulating the aggregation of the amyloid-beta peptide in Alzheimer's Disease (AD).

ING4 Promotes Stemness Enrichment of Human Renal Cell Carcinoma Cells Through Inhibiting DUSP4 Expression to Activate the p38 MAPK/type I IFN-Stimulated Gene Signaling Pathway

Renal cell carcinoma (RCC) recurs frequently due to high metastatic spread, resulting in a high mortality. Cancer stem cells play a critical role in initiating the tumor metastasis. Inhibitor of growth 4 (ING4) is a member of the ING family, but its impact on cancer stem cells in RCC is still unknown. In this study, we found that ING4 significantly promoted the sphere-forming size and number of RCC cells under an ultralow-attachment culture condition in vitro, tumor growth and metastasis in vivo, and the expression of some stem-like or pluripotent biomarkers CD44, MYC, OCT4, and NANOG, indicating that ING4 increased the stemness enrichment of RCC cells. Mechanistically, the ING4-activated p38 MAPK pathway possibly upregulated the expression of type I IFN-stimulated genes to promote the formation of RCC stem cells. ING4 could inhibit the expression of DUSP4 to activate p38 MAPK. In addition, selective pharmacological p38 MAPK inhibitors could significantly inhibit stemness enrichment only in ING4-overexpressed RCC cells, suggesting that the p38 MAPK inhibitors might be effective in patients with high ING4 expression in RCC tissue. Taken together, our findings proposed that ING4 might serve as a potential therapeutic target for metastatic RCC, particularly RCC stem cells.

Combination of Compound Kushen Injection and cisplatin shows synergistic antitumor activity in p53-R273H/P309S mutant colorectal cancer cells through inducing apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Colorectal cancer (CRC) is one type of worldwide popular and refractory tumors. Compound Kushen Injection (CKI) is a frequently applied traditional Chinese medicine formula as an adjuvant drug for the chemotherapy of CRC. P53 is the most commonly mutated gene in CRC, accounting for the development, malignant and prognosis progression of CRC. However, effect of CKI on the therapeutic efficacy of p53-mutant CRC remains understood. Besides, the combined efficacy of different chemotherapeutics drugs in combination with CKI for CRC treatment is rarely concerned.

AIM OF STUDY

To investigate the combined efficacy of the CKI-derived combination strategies in the p53-mutant CRC.

MATERIALS AND METHODS

Two CRC cell lines HCT116 and SW480 cells, which respectively harbor wild-type p53 and p53-R273H/P309S mutant, were applied. Cisplatin (Cis) and 5-fluorouracil (5FU) were combined chemotherapeutics drugs of CKI-derived combination strategies in this article. In vitro antitumor activity was detected by sulforhodamine B (SRB) assay and colony formation assay. Combenefit soft was applied to evaluate the synergetic/antagonistic effect of drug combination. Lentivirus-mediated overexpression method was used to generate a set of p53-mutant and wild-type CRC cell lines harboring identical genomes. Transcriptomics and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were applied to predicate the underlying mechanism of synergetic interaction between drug combination. Western blot was performed to verify predicated pathways contributing to the synergy of drug combination.

RESULTS

CKI preferentially combined with Cis but not 5FU, to produce a synergistical antitumor efficiency for p53-R273H/P309S mutant, rather than wild-type p53 harboring CRC cells. The combination of CKI and Cis strongly reprogrammed the transcriptional profiles of SW480 cells. Cytokine-cytokine receptor interaction pathway was a key pathway involved in cooperativity between CKI and Cis in SW480 cells. Mechanistically, compared to that Cis individually triggered necroptosis, the co-treatment of CKI and Cis reinforced the cell death of SW480 cells in a possible synergistic manner by inducing extrinsic apoptosis pathway.

CONCLUSION

This article provides a novel perspective into the precision clinical application of CKI-derived combination therapy programs of CRC based on genetic variation and the classes of chemotherapeutics drugs.

Natural Small Molecules Enabled Efficient Immunotherapy through Supramolecular Self-Assembly in P53-Mutated Colorectal Cancer

Nanomedicine, constructed from therapeutics, presents an advantage in drug delivery for cancer therapies. However, nanocarrier-based treatment systems have problems such as interbatch variability, multicomponent complexity, poor drug delivery, and carrier-related toxicity. To solve these issues, the natural molecule honokiol (HK), an anticancer agent in a phase I clinical trial (CTR20170822), was used to form a self-assembly nanoparticle (SA) through hydrogen bonding and hydrophobicity. The preparation of SA needs no molecular precursors or excipients in aqueous solution, and 100% drug-loaded SA exhibited superior tumor-targeting ability due to the enhanced permeability and retention (EPR) effect. Moreover, SA significantly enhanced the antitumor immunity relative to free HK, and the mechanism has notable selectivity to the p53 pathway. Furthermore, SA exhibited excellent physiological stability and inappreciable toxicity. Taken together, this supramolecular self-assembly strategy provides a safe and "molecular economy" model for rational design of clinical therapies and is expected to promote targeted therapy of HK, especially in colorectal cancer patients with obvious p53 status.

Efficient enantioselective synthesis of CF2H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine]s via organocatalytic cycloaddition

A novel kind of CF2H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine] has been achieved via an organocatalyzed 1,3-dipole reaction.

MIR-4507 Targets TP53 to Facilitate the Malignant Progression of Non-small-cell Lung Cancer

Lung cancer is a serious threat to human health due to its high morbidity and mortality. microRNAs (miRNAs) are involved in the tumorigenesis and progression of lung cancer. In this study, we elucidated the role of miRNA-4507 (miR-4507) in the pathogenesis of non-small-cell lung cancer (NSCLC). miR-4507 is found to be upregulated in NSCLC cells (A549, H460). MTT, 5-ethynyl-2'-deoxyuridine (EdU), wound healing, and transwell assays were performed to evaluate NSCLC cell proliferation and migration. The results demonstrated that miR-4507 inhibition significantly decrease the proliferation and migration of NSCLC cells. Subsequently, a luciferase activity assay was conducted to verify the regulation of the predicted gene target of miR-4507, namely, TP53. Mechanism experiments show that miR-4507 activates the PI3K/AKT signal. Further, we co-transfected miR-4507 mimics and TP53 plasmids and found that TP53 overexpression could recover the effects of miR-4507 mimics on proliferation, migration, and the PI3K/AKT signal activation. These results suggested that miR-4507 targets TP53 to facilitate the proliferation and migration of lung cancer cells through PI3K/AKT signal and that miR-4507 could serve as a potential target for NSCLC treatment.

Bypassing the Resistance Mechanisms of the Tumor Ecosystem by Targeting the Endoplasmic Reticulum Stress Pathway Using Ruthenium- and Osmium-Based Organometallic Compounds: An Exciting Long-Term Collaboration with Dr. Michel Pfeffer

Metal complexes have been used to treat cancer since the discovery of cisplatin and its interaction with DNA in the 1960’s. Facing the resistance mechanisms against platinum salts and their side effects, safer therapeutic approaches have been sought through other metals, including ruthenium. In the early 2000s, Michel Pfeffer and his collaborators started to investigate the biological activity of organo-ruthenium/osmium complexes, demonstrating their ability to interfere with the activity of purified redox enzymes. Then, they discovered that these organo-ruthenium/osmium complexes could act independently of DNA damage and bypass the requirement for the tumor suppressor gene TP53 to induce the endoplasmic reticulum (ER) stress pathway, which is an original cell death pathway. They showed that other types of ruthenium complexes—as well complexes with other metals (osmium, iron, platinum)—can induce this pathway as well. They also demonstrated that ruthenium complexes accumulate in the ER after entering the cell using passive and active mechanisms. These particular physico-chemical properties of the organometallic complexes designed by Dr. Pfeffer contribute to their ability to reduce tumor growth and angiogenesis. Taken together, the pioneering work of Dr. Michel Pfeffer over his career provides us with a legacy that we have yet to fully embrace.

Strategies for targeting undruggable targets

INTRODUCTION

Undruggable targets refer to clinically meaningful therapeutic targets that are 'difficult to drug' or 'yet to be drugged' via traditional approaches. Featuring characteristics of lacking defined ligand-binding pockets, non-catalytic protein-protein interaction functional modes and less-investigated 3D structures, these undruggable targets have been targeted with novel therapeutic entities developed with the progress of unconventional drug discovery approaches, such as targeted degradation molecules and display technologies.

AREA COVERED

This review first presents the concept of 'undruggable' exemplified by RAS and other targets. Next, detailed strategies are illustrated in two aspects: innovation of therapeutic entities and development of unconventional drug discovery technologies. Finally, case studies covering typical undruggable targets (Bcl-2, p53, and RAS) are depicted to further demonstrate the feasibility of the strategies and entities above.

EXPERT OPINION

Targeting the undruggable expands the scope of therapeutically reachable targets. Consequently, it represents the drug discovery frontier. Biomedical studies are capable of dissecting disease mechanisms, thus broadening the list of undruggable targets. Encouraged by the recent approval of the KRAS inhibitor Sotorasib, we believe that merging multiple discovery approaches and exploiting various novel therapeutic entities would pave the way for dealing with more 'undruggable' targets in the future.

p53 regulated senescence mechanism and role of its modulators in age-related disorders

Multiple co-morbidities are associated with age, and there is a need for the broad-spectrum drug to prevent multiple regimens that may cause an adverse effect in the geriatric population. Cellular senescence is a primary mechanism for ageing in various tissues. p53, a tumor suppressor protein, plays a significant role in forming DNA damage foci and post different stress responses. DNA damage foci can be transient or persistent that can progress to DNA-SCARS inducing senescence. p53 also plays a role in apoptosis and negative regulation of SASP. Few upstream targets like FOXO4, MDM2, MDM4, USP7 control the availability of p53 for apoptosis. Hence, the senolytic therapies, modulating p53 upstream targets, can be a good approach for preventing age-related disorders. This review discusses the insights on the role of p53 in the formation of DNA-SCARS, various upstream target proteins, and pathways involved in p53 regulation. Further, the review aimed to include recently discovered small molecules acting on these upstream targets, and those can be modified using medicinal chemistry approaches to give successful senotherapeutics.

Phase separation of p53 precedes aggregation and is affected by oncogenic mutations and ligands

Mutant p53 tends to form aggregates with amyloid properties, especially amyloid oligomers inside the nucleus, which are believed to cause oncogenic gain-of-function (GoF). The mechanism of the formation of the aggregates in the nucleus remains uncertain. The present study demonstrated that the DNA-binding domain of p53 (p53C) underwent phase separation (PS) on the pathway to aggregation under various conditions. p53C phase separated in the presence of the crowding agent polyethylene glycol (PEG). Similarly, mutant p53C (M237I and R249S) underwent PS; however, the process evolved to a solid-like phase transition faster than that in the case of wild-type p53C. The data obtained by microscopy of live cells indicated that transfection of mutant full-length p53 into the cells tended to result in PS and phase transition (PT) in the nuclear compartments, which are likely the cause of the GoF effects. Fluorescence recovery after photobleaching (FRAP) experiments revealed liquid characteristics of the condensates in the nucleus. Mutant p53 tended to undergo gel- and solid-like phase transitions in the nucleus and in nuclear bodies demonstrated by slow and incomplete recovery of fluorescence after photobleaching. Polyanions, such as heparin and RNA, were able to modulate PS and PT in vitro. Heparin apparently stabilized the condensates in a gel-like state, and RNA apparently induced a solid-like state of the protein even in the absence of PEG. Conditions that destabilize p53C into a molten globule conformation also produced liquid droplets in the absence of crowding. The disordered transactivation domain (TAD) modulated both phase separation and amyloid aggregation. In summary, our data provide mechanistic insight into the formation of p53 condensates and conditions that may result in the formation of aggregated structures, such as mutant amyloid oligomers, in cancer. The pathway of mutant p53 from liquid droplets to gel-like and solid-like (amyloid) species may be a suitable target for anticancer therapy.

Mutant p53 tends to form aggregates with amyloid properties, especially amyloid oligomers inside the nucleus, which are believed to cause oncogenic gain-of-function (GoF).

Synthesis of RNA-based gene regulatory devices for redirecting cellular signaling events mediated by p53

Rationale: The p53 gene is a well-known tumor suppressor, and its mutation often contributes to the occurrence and development of tumors. Due to the diversity and complexity of p53 mutations, there is still no effective p53 gene therapy. In this study, we designed and constructed an aptazyme switch that could effectively sense cellular wild-type p53 protein and regulate downstream gene function flexibly. The application of this artificial device in combination with Cre-LoxP and dCas9-VP64 tools achieved a precisely targeted killing effect on tumor cells. Methods: The affinity of the aptamer to p53 protein was verified by SPR. p53 aptazyme and gene circuits were chemically synthesized. The function of the gene circuit was detected by cell proliferation assay, apoptosis assay and Western blot. The nude mouse transplantation tumor experiment was used to evaluate the inhibitory effect of gene circuits on tumor cells in vivo. Results: The results of the SPR experiment showed that the p53 aptamer RNA sequence had a robust binding effect with p53 protein. The p53 aptazyme could efficiently sense wild-type p53 protein and initiate self-cleavage in cells. The Cre-p53 aptazyme gene circuit and dCas9-VP64/sgRNA mediated gene circuit designed based on p53 aptazyme significantly inhibited the growth and promoted the apoptosis of wild-type p53-deficient cancer cells in vitro. In addition, the gene circuits also had a significant inhibitory effect on tumors in vivo. Conclusion: The study developed a novel and efficient ribozyme switch for p53-specific recognition and provided a modular strategy for aptazyme binding to cellular proteins. In addition, the p53 aptazyme successfully inhibited tumor growth through a combined application with other synthetic biological tools, providing a new perspective for cancer therapy.

A Light-Inducible Split-dCas9 System for Inhibiting the Progression of Bladder Cancer Cells by Activating p53 and E-cadherin

Optogenetic systems have been increasingly investigated in the field of biomedicine. Previous studies had found the inhibitory effect of the light-inducible genetic circuits on cancer cell growth. In our study, we applied an AND logic gates to the light-inducible genetic circuits to inhibit the cancer cells more specifically. The circuit would only be activated in the presence of both the human telomerase reverse transcriptase (hTERT) and the human uroplakin II (hUPII) promoter. The activated logic gate led to the expression of the p53 or E-cadherin protein, which could inhibit the biological function of tumor cells. In addition, we split the dCas9 protein to reduce the size of the synthetic circuit compared to the full-length dCas9. This light-inducible system provides a potential therapeutic strategy for future bladder cancer.

An integrated view of p53 dynamics, function, and reactivation

The tumor suppressor p53 plays a vital role in responding to cell stressors such as DNA damage, hypoxia, and tumor formation by inducing cell-cycle arrest, senescence, or apoptosis. Expression level alterations and mutational frequency implicates p53 in most human cancers. In this review, we show how both computational and experimental methods have been used to provide an integrated view of p53 dynamics, function, and reactivation potential. We argue that p53 serves as an exceptional case study for developing methods in modeling intrinsically disordered proteins. We describe how these methods can be leveraged to improve p53 reactivation molecule design and other novel therapeutic modalities, such as PROteolysis TARgeting Chimeras (PROTACs).

Making Connections: p53 and the Cathepsin Proteases as Co-Regulators of Cancer and Apoptosis

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the p53 and cathepsin proteins. While it has been demonstrated that the p53 protein can directly induce the leakage of cathepsin proteases from the lysosome, directly triggering cell death, little is known about what factors set the threshold at which the lysosome can become permeabilized. It appears that the expression levels of cathepsin proteases may be central to this process, with some of them being transcriptionally regulated by p53. The consequences of such a mechanism have serious implications for lysosomal-mediated apoptosis and have significant input into the design of therapeutics and their strategic use. In this review, we highlight the importance of extending such findings to other cathepsin family members and the need to assess the roles of p53 isoforms and mutants in furthering this mechanism.

Abstract

While viewed as the “guardian of the genome”, the importance of the tumor suppressor p53 protein has increasingly gained ever more recognition in modulating additional modes of action related to cell death. Slowly but surely, its importance has evolved from a mutated genetic locus heavily implicated in a wide array of cancer types to modulating lysosomal-mediated cell death either directly or indirectly through the transcriptional regulation of the key signal transduction pathway intermediates involved in this. As an important step in determining the fate of cells in response to cytotoxicity or during stress response, lysosomal-mediated cell death has also become strongly interwoven with the key components that give the lysosome functionality in the form of the cathepsin proteases. While a number of articles have been published highlighting the independent input of p53 or cathepsins to cellular homeostasis and disease progression, one key area that warrants further focus is the regulatory relationship that p53 and its isoforms share with such proteases in regulating lysosomal-mediated cell death. Herein, we review recent developments that have shaped this relationship and highlight key areas that need further exploration to aid novel therapeutic design and intervention strategies.