A natural product, Piperlongumine (PL), increases tumor cells sensitivity to NK cell killing

Targeting oxidative stress-mediated regulated cell death as a vulnerability in cancer

Reactive oxygen species (ROS), regulators of cellular behaviors ranging from signaling to cell death, have complex production and control mechanisms to maintain a dynamic redox balance under physiological conditions. Redox imbalance is frequently observed in tumor cells, where ROS within tolerable limits promote oncogenic transformation, while excessive ROS induce a range of regulated cell death (RCD). As such, targeting ROS-mediated regulated cell death as a vulnerability in cancer. However, the precise regulatory networks governing ROS-mediated cancer cell death and their therapeutic applications remain inadequately characterized. In this Review, we first provide a comprehensive overview of the mechanisms underlying ROS production and control within cells, highlighting their dynamic balance. Next, we discuss the paradoxical nature of the redox system in tumor cells, where ROS can promote tumor growth or suppress it, depending on the context. We also systematically explored the role of ROS in tumor signaling pathways and revealed the complex ROS-mediated cross-linking networks in cancer cells. Following this, we focus on the intricate regulation of ROS in RCD and its current applications in cancer therapy. We further summarize the potential of ROS-induced RCD-based therapies, particularly those mediated by drugs targeting specific redox balance mechanisms. Finally, we address the measurement of ROS and oxidative damage in research, discussing existing challenges and future prospects of targeting ROS-mediated RCD in cancer therapy. We hope this review will offer promise for the clinical application of targeting oxidative stress-mediated regulated cell death in cancer therapy.

Enhancing NK Cell Antitumor Activity With Natural Compounds: Research Advances and Molecular Mechanisms

In recent years, immunotherapy has become a novel antitumor strategy in addition to traditional surgery, radiotherapy, and chemotherapy and has exhibited promising results in clinical applications. Despite significant breakthroughs in immunotherapy, such as immune checkpoint blockade and CAR-T cell therapy, it remains necessary to develop more efficacious, safer, and cheaper immunotherapeutic drugs due to factors including small reaction populations, acquired resistance, adverse side effects, and high costs. Natural killer (NK) cells are preeminent cytotoxic lymphocytes of the innate immune system that act as the first line of defense against tumors and synergistically enhance the adaptive immune response of T lymphocytes. Therefore, boosting the antitumor function of NK cells is an important direction in the development of immunotherapy. For decades, various immunotherapies such as adoptive cell therapy, antibody drugs, cytokines supplement, and chemical immunomodulators have been developing rapidly to improve the function of NK cells. Compared to biological immunotherapy, immunomodulators derived from natural products have outstanding advantages of low immunogenicity, multi-targeting, and cost-effectiveness. Currently, increasing attention is being focused on discovering NK cell-stimulating agents from natural products, such as polysaccharides, alkaloids, terpenoids, saponins, phenolics, and quinones. This review aims to categorize and summarize the comprehensive research progress on these natural products, discuss their potential molecular mechanisms in regulating NK cells, and explore their clinical applications as standalone treatments or in combination with conventional chemotherapy regimens.

Sodium valproate enhances efficacy of NKG2D CAR-T cells against glioblastoma

Chimeric antigen receptor T-cell (CAR-T) therapies have shown promise in glioblastoma clinical studies, but responses remain inconsistent due to heterogeneous tumor antigen expression and immune evasion post-treatment. NKG2D CAR-T cells have demonstrated a favorable safety profile in patients with hematologic tumors, and showed robust antitumor efficacy in various xenograft models, including glioblastoma. However, malignant glioma cells evade immunological surveillance by reducing NKG2D ligands expression or cleavage. To enhance the effectiveness of NKG2D CAR-T therapy, we investigated the potential of combining NKG2D CAR-T with approved drugs that cross the blood-brain barrier and augment NKG2D ligands expression in glioma cells. We found that sodium valproate (VPA), an antiepileptic drug, significantly increased surface NKG2D ligands expression on glioblastoma cells at a sublethal concentration. VPA treatment enhanced the susceptibility of glioblastoma cells to NKG2D CAR-T mediated cytotoxicity in both 2D monolayer and 3D tumor spheroid models in vitro. Moreover, VPA-treated glioblastoma cells stimulated CAR-T cells to produce higher levels of inflammatory cytokines (IL-2, IFN-γ, and IL-6). Mechanistically, VPA upregulated NKG2D ligands expression via the PI3K/Akt signaling pathway. Additionally, VPA treatment augmented the antitumor activity of NKG2D CAR-T cells in a glioblastoma xenograft model in vivo. These preclinical results suggest that combining VPA with NKG2D CAR-T therapy represents a promising strategy for improving glioblastoma treatment, warranting further clinical investigation.

Exploring the Therapeutic Potential of BBB-Penetrating Phytochemicals With p38 MAPK Modulatory Activity in Addressing Oxidative Stress-Induced Neurodegenerative Disorders, With a Focus on Alzheimer's Disease

Oxidative stress plays an important role in the occurrence of neurodegenerative diseases. Previous studies indicate a strong connection between oxidative stress, inappropriate activation of the p38 MAPK signaling pathway, and the pathogenesis of neurodegenerative diseases. Although antioxidant therapy is a valid strategy to alleviate these problems, the most important limitation of this approach is the ineffectiveness of drug administration due to the limited permeability of the BBB. Therefore, BBB-penetrating p38 MAPK modulators with proper antioxidant capacity could be useful in preventing/reducing the complications of neurodegenerative disorders. The current manuscript aims to review the therapeutic capabilities of some recently reviewed naturally occurring p38 MAPK inhibitors in the management of neurodegenerative problems such as Alzheimer's disease. In data collection, we tried to use more recent studies published in high-quality journals indexed in databases Scopus, Web of Science, PubMed, and so on, but no specific time frame was considered due to the nature of the study. Our evaluations indicate that natural compounds tanshinones, protoberberines, pinocembrin, osthole, rhynchophylline, oxymatrine, schisandrin, piperine, paeonol, ferulic acid, 6-gingerol, obovatol, and trolox have significant potential for use as supplements/adjuvants in the reduction of neurodegenerative-related problems. Our findings emphasize the usefulness of BBB-penetrating phytochemicals with p38 MAPK modulatory activity as potential therapeutic options against neurodegenerative disorders. Of course, the proper use of these compounds depends on considering their toxicity/safety profile and pharmacokinetic characteristics as well as the clinical conditions of users.

Alkaloids in Cancer therapy: Targeting the tumor microenvironment and metastasis signaling pathways

The use of phytomedicine in cancer therapy is a growing field of research that takes use of the medicinal properties of plant-derived compounds. Under the domain of cancer therapy and management, alkaloids, a prominent group of natural compounds, have showed significant potential. Alkaloids often affect a wide range of essential cellular mechanisms involved in cancer progression. These multi-targeting capabilities, can give significant advantages to alkaloids in overcoming resistance mechanisms. For example, berberine, an alkaloid found in Berberis species, is widely reported to induce apoptosis by activating caspases and regulating apoptotic pathways. Notably, alkaloids like as quinine have showed promise in inhibiting the formation of new blood vessels required for tumor growth. In addition, alkaloids have shown anti-proliferative and anticancer properties mostly via modulating key signaling pathways involved in metastasis, including those regulating epithelial-mesenchymal transition. This work provides a comprehensive overview of naturally occurring alkaloids that exhibit anticancer properties, with a specific emphasis on their underlying molecular mechanisms of action. Furthermore, many methods to modify previously reported difficult physicochemical properties using nanocarriers in order to enhance its systemic bioavailability have been discussed as well. This study also includes information on newly discovered alkaloids that are now being studied in clinical trials for their potential use in cancer treatment. Further, we have also briefly mentioned on the application of high-throughput screening and molecular dynamics simulation for acceleration on the identification of potent alkaloids based compounds to target and treat cancer.

Design, synthesis, and biological studies of nitric oxide-donating piperlongumine derivatives triggered by lysyl oxidase as anti-triple negative breast cancer agents

Nitric oxide (NO) is an important gas messenger molecule with a wide range of biological functions. High concentration of NO exerts promising antitumor effects and is regarded as one of the hot spots in cancer research, that have limitations in their direct application due to its gaseous state, short half-life (seconds) and high reactivity. Lysyl oxidase (LOX) is a copper-dependent amine oxidase that is responsible for the covalent bonding between collagen and elastin and promotes tumor cell invasion and metastasis. The overexpression of LOX in triple-negative breast cancer (TNBC) makes it an attractive target for TNBC therapy. Herein, novel NO donor prodrug molecules were designed and synthesized based on the naturally derived piperlongumine (PL) skeleton, which can be selectively activated by LOX to release high concentrations of NO and PL derivatives, both of them play a synergistic role in TNBC therapy. Among them, the compound TM-1 selectively released NO in highly invasive TNBC cells (MDA-MB-231), and TM-1 was also confirmed as a potential TNBC cell line inhibitor with an inhibitory concentration of 2.274 μM. Molecular docking results showed that TM-1 had a strong and selective binding affinity with LOX protein.

Piperlongumine inhibits antioxidant enzymes, increases ROS levels, induces DNA damage and G2/M cell cycle arrest in breast cell lines

Piperlongumine (PLN) is a biologically active alkaloid/amide derived from Piper longum, with known promising anticancer activity. The aim of this study was to compare the antiproliferative activity of PLN in human breast MCF-7 adenocarcinoma cell line with effects in HB4a normal mammary epithelial non-tumor cell line. The parameters examined were cell growth, viability, reactive oxygen species (ROS) levels and DNA damage, as well as the effects on the modulating targets responsible through regulation of these pathways. PLN increased ROS levels and expression of the SOD1 antioxidant enzyme. PLN inhibited the expression of the antioxidant enzymes catalase, TRx1, and PRx2. The ability of PLN to inhibit antioxidant enzyme expression was associated with the oxidative stress response. PLN induced genotoxicity in both cell lines and upregulated the levels of GADD45A mRNA and p21 protein. The DNA damage response ATR protein was downregulated in both cell lines and contributed to an enhanced PLN genotoxicity. In HB4a cells, Chk1 protein, and mRNA levels were also decreased. In response to elevated ROS levels and DNA damage induction, the cells were arrested at the G2/M phase, probably in an attempt to promote cell survival. Although cell viability was reduced in both cell lines, only HB4a cells underwent apoptotic cell death, whereas other types of cellular death may be involved in MCF-7 cells. Taken together, these data provide insight into the anticancer mechanisms attributed to PLN effects, which acts as an inhibitor of DNA damage response (DDR) proteins and antioxidant enzymes.

Flow cytometry conjugate formation assay between natural killer cells and their target cells

Before being able to kill other cells, natural killer (NK) cells first have to establish contact with those targets. In case of a predominance of activating signals from the target cell over inhibitory ones, the killing process is initiated. It is possible, with a simple two-color flow cytometry method, to evaluate, for any given effector cell-target cell pair, the number of conjugates between both types of cells. The percentage obtained gives an idea of the amplitude of binding of the NK cells to the targets and might be expected to be indicative of the level of cytotoxicity. Nevertheless, there is no absolute correlation, as the percentages of conjugates are sometimes higher with relatively resistant targets than with the highly sensitive cell line K562. Practically, NK cells and target cells are stained with two differently fluorescent dyes and incubated together at the desired effector:target ratio (in our example, 1:1) for various periods of time (0, 10, 30min, etc.) at 37°C. After the incubation time, the cells are carefully introduced into the flow cytometer, where in principle three populations are distinguished: the single positive, unconjugated effector and target cells, respectively, and the double positive subset, which corresponds to the conjugates between both cell types. We describe here in detail the staining and cell culture protocols and procedures, and give several examples. Thus, the very cytotoxic NK leukemia cell line KHYG-1 versus the myeloid leukemia K562 (the "conventional" NK cell target) and the Burkitt lymphoma cell line Raji forms a high number of conjugates. In contrast, purified, non-activated, healthy donor-derived peripheral blood NK cells bind less to the targets, in accordance with their low (K562) or absent (Raji) cytotoxic activity.

Suppression of protein quality control system by TRIM30a sensitises tumour cells to NK cell-mediated immune surveillance

Tumorigenesis entails circumventing cell-intrinsic regulatory mechanisms while avoiding extrinsic immune surveillance and other host defence systems. Nevertheless, how tumour cells' ability to eliminate misfolded proteins affects immune surveillance remains poorly understood. In this study, we find that overexpression of murine tripartite motif-containing protein 30a (TRIM30a) sensitises tumour cells to natural killer (NK) cells-mediated cytolysis. TRIM30a has no effect on tumour cell proliferation or apoptosis in vitro. However, TRIM30a-overexpressing tumour cells grow substantially slower than control tumour cells in immune-competent mice but not in NK cell-depleted mice. [Correction added on 04 October 2023, after first online publication: 'NK-depleted' has been changed to 'NK cell-depleted' in the preceding sentence.] Mechanistically, TRIM30a overexpression impedes the clearance of misfolded proteins and increases the production of reactive oxygen species induced by proteotoxic stress, implying that TRIM30a impairs protein quality control (PQC) systems in tumour cells. Furthermore, TRIM30a reduces expression of genes encoding proteasome subunits and antioxidant proteins. Our study demonstrates that TRIM30a is a potential tumour suppressor and immune modulator that promotes tumour cytolysis by NK cells, and suggests that an enhanced PQC and antioxidant capacity is an integral part of the immune escape mechanism during tumorigenesis.

The Antitumor Activity of Piplartine: A Review

Cancer is a worldwide health problem with high mortality in children and adults, making searching for novel bioactive compounds with potential use in cancer treatment essential. Piplartine, also known as piperlongumine, is an alkamide isolated from Piper longum Linn, with relevant therapeutic potential. Therefore, this review covered research on the antitumor activity of piplartine, and the studies reported herein confirm the antitumor properties of piplartine and highlight its possible application as an anticancer agent against various types of tumors. The evidence found serves as a reference for advancing mechanistic research on this metabolite and preparing synthetic derivatives or analogs with better antitumor activity in order to develop new drug candidates.

Antitumor Mechanisms of Molecules Secreted by Trypanosoma cruzi in Colon and Breast Cancer: A Review

BACKGROUND

Molecules secreted by Trypanosoma cruzi (T. cruzi) have beneficial effects on the immune system and can fight against cancer by inhibiting the growth of tumor cells, preventing angiogenesis, and promoting immune activation.

OBJECTIVE

This study aimed to investigate the effects of molecules secreted by Trypanosoma cruzi on the growth of colon and breast cancer cells, to understand the underlying mechanisms of action.

RESULTS

Calreticulin from T. cruzi, a 45 kDa protein, participates in essential changes in the tumor microenvironment by triggering an adaptive immune response, exerting an antiangiogenic effect, and inhibiting cell growth. On the other hand, a 21 kDa protein (P21) secreted at all stages of the parasite's life cycle can inhibit cell invasion and migration. Mucins, such as Tn, sialyl-Tn, and TF, are present both in tumor cells and on the surface of T. cruzi and are characterized as common antigenic determinants, inducing a cross-immune response. In addition, molecules secreted by the parasite are used recombinantly in immunotherapy against cancer for their ability to generate a reliable and long-lasting immune response.

CONCLUSION

By elucidating the antitumor mechanisms of the molecules secreted by T. cruzi, this study provides valuable insights for developing novel therapeutic strategies to combat colon and breast cancer.

GPC3-targeted CAR-T cells secreting B7H3-targeted BiTE exhibit potent cytotoxicity activity against hepatocellular carcinoma cell in the in vitro assay

Hepatocellular carcinoma (HCC), the most common primary liver cancer has a high mortality in China, and it is usually diagnosed at a late stage, thereby leaving patients with few effective treatment options. Chimeric antigen receptor-T (CAR-T) cell therapy, a novel immunotherapy that has shown promising results in leukemia, lymphoma and multiple myeloma, is also expected to work well in solid tumors, including HCC. However, the ideal therapeutic efficacy has not yet been achieved, in part due to tumor antigen escape caused by antigen heterogeneity. To overcome such challenge, we screened a panel of biomarkers in HCC cell lines and found that GPC3 and B7H3 were highly expressed on HCC with expression heterogeneity. Then we developed a novel bispecific T cell engagers CAR-T (CAR.T-BiTEs) that drives the expression of a CAR specific for GPC3 and BiTEs against CD3 and B7H3, herein referred to as “GPC3-BiTE CAR.” We found that BiTEs promoted the increased activation of untransduced T cells and IFN-γ release. Moreover, BiTEs secreted by GPC3-BiTE CAR-HEK293T cells promoted increased cytotoxicity activity of untransduced T cells against GPC3+/B7H3+ (GPC3 positive/B7H3 positive) and GPC3-/B7H3+(GPC3 negative/B7H3 positive) HCC cell lines. In vitro function assays showed that GPC3-BiTE CAR-T cells exhibited greater cytotoxicity activity against GPC3+/B7H3+ HCC cell lines than GPC3 CAR-T cells (GPC3-targeted CAR-T cells) and B7H3 CAR-T cells (B7H3-targeted CAR-T cells). Furthermore, GPC3-BiTE CAR-T cells exhibited superior cytotoxicity against GPC3 negative HCC cell lines compared with GPC3 CAR T cells. In conclusion, our study showed that GPC3-BiTE CAR T cells exhibited superior antitumor activity than single-target CAR-T cells and can overcome tumor escape induced by antigen heterogeneity, suggesting that this could be a promising therapeutic strategy for HCC.

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The expression of GPC3 and B7H3 was heterogeneous in HCC tissues.

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BiTEs enhanced the cytotoxicity of untransduced T cells against HCC cell lines.

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GPC3-BiTE CAR-T cells showed enhanced cytotoxicity against GPC3+/B7H3+ cells.

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GPC3-BiTE CAR-T cells can resist GPC3 antigen escape in the in vitro assay.

TRIM family proteins: roles in proteostasis and neurodegenerative diseases

Neurodegenerative diseases (NDs) are a diverse group of disorders characterized by the progressive degeneration of the structure and function of the central or peripheral nervous systems. One of the major features of NDs, such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD), is the aggregation of specific misfolded proteins, which induces cellular dysfunction, neuronal death, loss of synaptic connections and eventually brain damage. By far, a great amount of evidence has suggested that TRIM family proteins play crucial roles in the turnover of normal regulatory and misfolded proteins. To maintain cellular protein quality control, cells rely on two major classes of proteostasis: molecular chaperones and the degradative systems, the latter includes the ubiquitin-proteasome system (UPS) and autophagy; and their dysfunction has been established to result in various physiological disorders including NDs. Emerging evidence has shown that TRIM proteins are key players in facilitating the clearance of misfolded protein aggregates associated with neurodegenerative disorders. Understanding the different pathways these TRIM proteins employ during episodes of neurodegenerative disorder represents a promising therapeutic target. In this review, we elucidated and summarized the diverse roles with underlying mechanisms of members of the TRIM family proteins in NDs.

Synergistic Tumor Cytolysis by NK Cells in Combination With a Pan-HDAC Inhibitor, Panobinostat

Histone deacetylases (HDAC) are frequently overexpressed in tumors, and their inhibition has shown promising anti-tumor effects. However, the synergistic effects of HDAC inhibition with immune cell therapy have not been fully explored. Natural killer (NK) cells are cytotoxic lymphocytes for anti-tumor immune surveillance, with immunotherapy potential. We showed that a pan-HDAC inhibitor, panobinostat, alone demonstrated anti-tumor and anti-proliferative activities on all tested tumors in vitro. Additionally, panobinostat co-treatment or pretreatment synergized with NK cells to mediate tumor cell cytolysis. Mechanistically, panobinostat treatment increased the expression of cell adhesion and tight junction-related genes, promoted conjugation formation between NK and tumor cells, and modulates NK cell-activating receptors and ligands on tumor cells, contributing to the increased tumor cytolysis. Finally, panobinostat therapy led to better tumor control and synergized with anti-PD-L1 therapy. Our data highlights the anti-tumor potential of HDAC inhibition through tumor-intrinsic toxicity and enhancement of NK -based immunotherapy.

Exploiting the CRISPR-Cas9 gene-editing system for human cancers and immunotherapy

The discovery of clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR-Cas9) technology has brought advances in the genetic manipulation of eukaryotic cells, which has revolutionised cancer research and treatment options. It is increasingly being used in cancer immunotherapy, including adoptive T and natural killer (NK) cell transfer, secretion of antibodies, cytokine stimulation and overcoming immune checkpoints. CRISPR-Cas9 technology is used in autologous T cells and NK cells to express various innovative antigen designs and combinations of chimeric antigen receptors (CARs) targeted at specific antigens for haematological and solid tumors. Additionally, advanced engineering in immune cells to enhance their sensing circuits with sophisticated functionality is now possible. Intensive research on the CRISPR-Cas9 system has provided scientists with the ability to overcome the hostile tumor microenvironment and generate more products for future clinical use, especially off-the-shelf, universal cellular products, bringing exciting milestones for immunotherapy. This review discussed the application and challenges of CRISPR technology in cancer research and immunotherapy, its advances and prospects for promoting new cell-based therapeutic beyond immune oncology.