Partial p53 reactivation is sufficient to induce cancer regression

The treatment landscape of triple-negative breast cancer

Triple-negative breast cancer (TNBC) tumors are biologically aggressive breast cancer. On the molecular level, TNBC is a highly heterogeneous disease; more biotechnologies are gradually being used to advance the understanding of TNBC subtypes and help establish more targeted therapies. Multiple TNBC target-related agents are already approved by the Food and Drug Administration for clinical use, including PI3K/AKT/mTOR inhibitors, PRAP inhibitors, and antibody-drug conjugates. Some innovative approaches, like peptide strategies, also promise to treat TNBC. Currently, the interplay between TNBC tumors and their tumor microenvironment provides a promising prospect for improving the efficacy of immunotherapy. In this review, we summarize the prevalent TNBC subtype methodologies, discuss the evolving therapeutic strategies, and propose new therapeutic possibilities based on existing foundational theories, with the attempt to serve as a reference to further advance tailoring treatment of TNBC.

Structural basis of p53 inactivation by cavity-creating cancer mutations and its implications for the development of mutant p53 reactivators

The cavity-creating p53 cancer mutation Y220C is an ideal paradigm for developing small-molecule drugs based on protein stabilization. Here, we have systematically analyzed the structural and stability effects of all oncogenic Tyr-to-Cys mutations (Y126C, Y163C, Y205C, Y220C, Y234C, and Y236C) in the p53 DNA-binding domain (DBD). They were all highly destabilizing, drastically lowering the melting temperature of the protein by 8-17 °C. In contrast, two non-cancerous mutations, Y103C and Y107C, had only a moderate effect on protein stability. Differential stabilization of the mutants upon treatment with the anticancer agent arsenic trioxide and stibogluconate revealed an interesting proximity effect. Crystallographic studies complemented by MD simulations showed that two of the mutations, Y234C and Y236C, create internal cavities of different size and shape, whereas the others induce unique surface lesions. The mutation-induced pockets in the Y126C and Y205C mutant were, however, relatively small compared with that of the already druggable Y220C mutant. Intriguingly, our structural studies suggest a pronounced plasticity of the mutation-induced pocket in the frequently occurring Y163C mutant, which may be exploited for the development of small-molecule stabilizers. We point out general principles for reactivating thermolabile cancer mutants and highlight special cases where mutant-specific drugs are needed for the pharmacological rescue of p53 function in tumors.

ERK pathway agonism for cancer therapy: evidence, insights, and a target discovery framework

At least 40% of human cancers are associated with aberrant ERK pathway activity (ERKp). Inhibitors targeting various effectors within the ERKp have been developed and explored for over two decades. Conversely, a substantial body of evidence suggests that both normal human cells and, notably to a greater extent, cancer cells exhibit susceptibility to hyperactivation of ERKp. However, this vulnerability of cancer cells remains relatively unexplored. In this review, we reexamine the evidence on the selective lethality of highly elevated ERKp activity in human cancer cells of varying backgrounds. We synthesize the insights proposed for harnessing this vulnerability of ERK-associated cancers for therapeutical approaches and contextualize these insights within established pharmacological cancer-targeting models. Moreover, we compile the intriguing preclinical findings of ERK pathway agonism in diverse cancer models. Lastly, we present a conceptual framework for target discovery regarding ERKp agonism, emphasizing the utilization of mutual exclusivity among oncogenes to develop novel targeted therapies for precision oncology.

Translating p53-based therapies for cancer into the clinic

Inactivation of the most important tumour suppressor gene TP53 occurs in most, if not all, human cancers. Loss of functional wild-type p53 is achieved via two main mechanisms: mutation of the gene leading to an absence of tumour suppressor activity and, in some cases, gain-of-oncogenic function; or inhibition of the wild-type p53 protein mediated by overexpression of its negative regulators MDM2 and MDMX. Because of its high potency as a tumour suppressor and the dependence of at least some established tumours on its inactivation, p53 appears to be a highly attractive target for the development of new anticancer drugs. However, p53 is a transcription factor and therefore has long been considered undruggable. Nevertheless, several innovative strategies have been pursued for targeting dysfunctional p53 for cancer treatment. In mutant p53-expressing tumours, the predominant strategy is to restore tumour suppressor function with compounds acting either in a generic manner or otherwise selective for one or a few specific p53 mutations. In addition, approaches to deplete mutant p53 or to target vulnerabilities created by mutant p53 expression are currently under development. In wild-type p53 tumours, the major approach is to protect p53 from the actions of MDM2 and MDMX by targeting these negative regulators with inhibitors. Although the results of at least some clinical trials of MDM2 inhibitors and mutant p53-restoring compounds are promising, none of the agents has yet been approved by the FDA. Alternative strategies, based on a better understanding of p53 biology, the mechanisms of action of compounds and treatment regimens as well as the development of new technologies are gaining interest, such as proteolysis-targeting chimeras for MDM2 degradation. Other approaches are taking advantage of the progress made in immune-based therapies for cancer. In this Review, we present these ongoing clinical trials and emerging approaches to re-evaluate the current state of knowledge of p53-based therapies for cancer.

Bioactive Components of Areca Nut: An Overview of Their Positive Impacts Targeting Different Organs

Areca catechu L. is a widely cultivated tropical crop in Southeast Asia, and its fruit, areca nut, has been consumed as a traditional Chinese medicinal material for more than 10,000 years, although it has recently attracted widespread attention due to potential hazards. Areca nut holds a significant position in traditional medicine in many areas and ranks first among the four southern medicines in China. Numerous bioactive compounds have been identified in areca nuts, including alkaloids, polyphenols, polysaccharides, and fatty acids, which exhibit diverse bioactive functions, such as anti-bacterial, deworming, anti-viral, anti-oxidant, anti-inflammatory, and anti-tumor effects. Furthermore, they also display beneficial impacts targeting the nervous, digestive, and endocrine systems. This review summarizes the pharmacological functions and underlying mechanisms of the bioactive ingredients in areca nut. This helps to ascertain the beneficial components of areca nut, discover its medicinal potential, and guide the utilization of the areca nut.

Transactivation by partial function P53 family mutants is increased by the presence of G-quadruplexes at a promoter site

The effect of mutations in the P53 family of transcription factors on their biological functions, including partial or complete loss of transcriptional activity, has been confirmed several times. At present, P53 family proteins showing partial loss of activity appear to be promising potential candidates for the development of novel therapeutic strategies which could restore their transcriptional activity. In this context, it is important to employ tools to precisely monitor their activity; in relation to this, non-canonical DNA secondary structures in promoters including G-quadruplexes (G4s) were shown to influence the activity of transcription factors. Here, we used a defined yeast assay to evaluate the impact of differently modeled G4 forming sequences on a panel of partial function P53 family mutant proteins. Specifically, a 22-mer G4 prone sequence (derived from the KSHV virus) and five derivatives that progressively mutate characteristic guanine stretches were placed upstream of a minimal promoter, adjacent to a P53 response element in otherwise isogenic yeast luciferase reporter strains. The transactivation ability of cancer-associated P53 (TA-P53α: A161T, R213L, N235S, V272L, R282W, R283C, R337C, R337H, and G360V) or Ectodermal Dyplasia syndromes-related P63 mutant proteins (ΔN-P63α: G134D, G134V and inR155) were tested. Our results show that the presence of G4 forming sequences can increase the transactivation ability of partial function P53 family proteins. These observations are pointing to the importance of DNA structural characteristics for accurate classification of P53 family proteins functionality in the context of the wide variety of TP53 and TP63 germline and somatic mutations.

Biological Effects of HDAC Inhibitors Vary with Zinc Binding Group: Differential Effects on Zinc Bioavailability, ROS Production, and R175H p53 Mutant Protein Reactivation

The coordination of zinc by histone deacetylase inhibitors (HDACi), altering the bioavailability of zinc to histone deacetylases (HDACs), is key to HDAC enzyme inhibition. However, the ability of zinc binding groups (ZBGs) to alter intracellular free Zn+2 levels, which may have far-reaching effects, has not been explored. Using two HDACis with different ZBGs, we documented shifts in intracellular free Zn+2 concentrations that correlate with subsequent ROS production. Next, we assayed refolding and reactivation of the R175H mutant p53 protein in vitro to provide greater biological context as the activity of this mutant depends on cellular zinc concentration. The data presented demonstrates the differential activity of HDACi in promoting R175H response element (RE) binding. After cells are treated with HDACi, there are differences in R175H mutant p53 refolding and reactivation, which may be related to treatments. Collectively, we show that HDACis with distinct ZBGs differentially impact the intracellular free Zn+2 concentration, ROS levels, and activity of R175H; therefore, HDACis may have significant activity independent of their ability to alter acetylation levels. Our results suggest a framework for reevaluating the role of zinc in the variable or off-target effects of HDACi, suggesting that the ZBGs of HDAC inhibitors may provide bioavailable zinc without the toxicity associated with zinc metallochaperones such as ZMC1.

Nutri-PEITC Jelly Significantly Improves Progression-Free Survival and Quality of Life in Patients with Advanced Oral and Oropharyngeal Cancer: A Blinded Randomized Placebo-Controlled Trial

TP53 mutation is associated with cancer progression. Novel strategies to reboot p53 are required to stabilize the disease and improve survival. This randomized placebo-controlled trial investigated safety and efficacy of Nutri-PEITC Jelly (a texture-modified nutritious diet fortified with β-phenethyl isothiocyanate (PEITC) on oral cancer. Seventy-two patients with advanced-staged oral or oropharyngeal cancer were randomly assigned to study and control groups, who consumed 200 g of Nutri-Jelly with and without 20 mg of PEITC, respectively, 5 days/week for 12 weeks. Outcomes, including adverse events, health-related quality of life (HRQOL), progression-free survival (PFS), tumor response, serum p53, and cytochrome c, were measured at 0, 1, and 3 months. Results show that the study group had a higher proportion of participants with improved HRQOL, stable disease, and increased serum p53 levels than those in the control group (p < 0.001). The PFS time in the study group was significantly longer than that of the control group (p < 0.05). Serum cytochrome c levels were non-significantly decreased in the study group. No serious intervention-related adverse events occurred in either group. In conclusion, Nutri-PEITC Jelly intake for 3 months is safe, stabilizes the disease, improves quality of life and progression-free survival, and might re-activate p53 in advanced-stage oral and oropharyngeal cancer patients.

Clinicopathologic features and abnormal signaling pathways in plasmablastic lymphoma: a multicenter study in China

BACKGROUND

Plasmablastic lymphoma (PBL) is a rare but aggressive B-cell lymphoma subtype with poor prognosis. Knowledge about the etiology, clinicopathologic and molecular features, and outcomes of PBL is limited. This study aimed to examine the clinicopathologic characteristics, therapeutic approaches, and clinical outcomes of PBL patients in a Chinese population.

METHODS

A total of 102 PBL patients were recruited from three cancer centers. The pathologic features and clinical outcomes of 56 patients with available treatment details and follow-up data were reviewed and analyzed. RNA sequencing was performed in 6 PBL and 11 diffuse large B-cell lymphoma (DLBCL) patients.

RESULTS

Most patients in our cohort were male (n = 36, 64.3%), and 35 patients presented with Ann Arbor stage I/II disease at diagnosis. All these patients showed negative findings for human immunodeficiency virus, and the vast majority of patients in our cohort were immunocompetent. Lymph nodes (n = 13, 23.2%) and gastrointestinal tract (n = 10, 17.9%) were the most commonly involved site at presentation. Post-treatment complete remission (CR) was the only prognostic factor affecting overall survival (OS) and progression-free survival (PFS) in the multivariate analysis. RNA-seq demonstrated that B-cell receptor (BCR), T-cell receptor (TCR), P53, calcium signaling, and Wnt signaling pathways were significantly downregulated in PBLs compared with GCB (or non-GCB) DLBCLs.

CONCLUSIONS

In this multicenter study in the Chinese population, PBL mainly occurred in immunocompetent individuals and most patients present with early-stage disease at diagnosis. Post-treatment CR was an important prognostic factor affecting OS and PFS. RNA-seq showed that the B-cell receptor (BCR), P53, calcium signaling, cell adhesion molecules, and Wnt signaling pathways significantly differed between PBL and GCB (or non-GCB) DLBCL, which provided theoretical basis for its pathogenesis and future treatment.

Gain of Function (GOF) Mutant p53 in Cancer-Current Therapeutic Approaches

Continuous development of personalized treatments is undoubtedly beneficial for oncogenic patients' comfort and survival rate. Mutant TP53 is associated with a worse prognosis due to the occurrence of metastases, increased chemoresistance, and tumor growth. Currently, numerous compounds capable of p53 reactivation or the destabilization of mutant p53 are being investigated. Several of them, APR-246, COTI-2, SAHA, and PEITC, were approved for clinical trials. This review focuses on these novel therapeutic opportunities, their mechanisms of action, and their significance for potential medical application.

Heparanase 2 (Hpa2) attenuates the growth of human sarcoma

The pro-tumorigenic properties of heparanase are well documented and established. In contrast, the role of heparanase 2 (Hpa2), a close homolog of heparanase, in cancer is not entirely clear. In carcinomas, Hpa2 is thought to attenuate tumor growth, possibly by inhibiting heparanase enzymatic activity. Here, we examine the role of Hpa2 in sarcoma, a group of rare tumors of mesenchymal origin, accounting for approximately 1% of all malignant tumors. Consistently, we found that overexpression of Hpa2 attenuates tumor growth while Hpa2 gene silencing results in bigger tumors. Mechanistically, attenuation of tumor growth by Hpa2 was associated with increased tumor stress conditions, involving ER stress, hypoxia, and JNK phosphorylation, leading to increased apoptotic cell death. In addition, overexpression of Hpa2 induces the expression of the p53 family member, p63 which, in sarcoma, functions to attenuate tumor growth. Moreover, we show that Hpa2 profoundly reduces stem cell characteristics of the sarcoma cells (stemness), most evident by failure of Hpa2 cells to grow as spheroids typical of stem cells. Likewise, expression of CD44, a well-established stem cell marker, was prominently decreased in Hpa2 cells. CD44 is also a cell surface receptor for hyaluronic acid (HA), a nonsulfated glycosaminoglycan that is enriched in connective tissues. Reduced expression of CD44 by Hpa2 may thus represent impaired cross-talk between Hpa2 and the extracellular matrix. Clinically, we found that Hpa2 is expressed by leiomyosarcoma tumor biopsies. Interestingly, nuclear localization of Hpa2 was associated with low-stage tumors. This finding opens a new direction in Hpa2 research.