TTF1 control of LncRNA synthesis delineates a tumor suppressor pathway directly regulating the ribosomal RNA genes

The tumor suppressor p14/19ARF regulates ribosomal RNA (rRNA) synthesis by controlling the nucleolar localization of Transcription Termination Factor 1 (TTF1). However, the role played by TTF1 in regulating the rRNA genes and in potentially controlling growth has remained unclear. We now show that TTF1 expression regulates cell growth by determining the cellular complement of ribosomes. Unexpectedly, it achieves this by acting as a "roadblock" to synthesis of the noncoding LncRNA and pRNA that we show are generated from the "Spacer Promoter" duplications present upstream of the 47S pre-rRNA promoter on the mouse and human ribosomal RNA genes. Unexpectedly, the endogenous generation of these noncoding RNAs does not induce CpG methylation or gene silencing. Rather, it acts in cis to suppress 47S preinitiation complex formation and hence de novo pre-rRNA synthesis by a mechanism reminiscent of promoter interference or occlusion. Taken together, our data delineate a pathway from p19ARF to cell growth suppression via the regulation of ribosome biogenesis by noncoding RNAs and validate a key cellular growth law in mammalian cells.

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

A glycolytic metabolite bypasses "two-hit" tumor suppression by BRCA2

Knudson's "two-hit" paradigm posits that carcinogenesis requires inactivation of both copies of an autosomal tumor suppressor gene. Here, we report that the glycolytic metabolite methylglyoxal (MGO) transiently bypasses Knudson's paradigm by inactivating the breast cancer suppressor protein BRCA2 to elicit a cancer-associated, mutational single-base substitution (SBS) signature in nonmalignant mammary cells or patient-derived organoids. Germline monoallelic BRCA2 mutations predispose to these changes. An analogous SBS signature, again without biallelic BRCA2 inactivation, accompanies MGO accumulation and DNA damage in Kras-driven, Brca2-mutant murine pancreatic cancers and human breast cancers. MGO triggers BRCA2 proteolysis, temporarily disabling BRCA2's tumor suppressive functions in DNA repair and replication, causing functional haploinsufficiency. Intermittent MGO exposure incites episodic SBS mutations without permanent BRCA2 inactivation. Thus, a metabolic mechanism wherein MGO-induced BRCA2 haploinsufficiency transiently bypasses Knudson's two-hit requirement could link glycolysis activation by oncogenes, metabolic disorders, or dietary challenges to mutational signatures implicated in cancer evolution.

LINC01021 Attenuates Expression and Affects Alternative Splicing of a Subset of p53-Regulated Genes

BACKGROUND

Loss of the p53-inducible LINC01021 in p53-proficient CRC cell lines results in increased sensitivity to DNA-damaging chemotherapeutics. Here, we comprehensively analyze how LINC01021 affects the p53-induced transcriptional program.

METHODS

Using a CRISPR/Cas9-approach, we deleted the p53 binding site in the LINC01021 promoter of SW480 colorectal cancer cells and subjected them to RNA-Seq analysis after the activation of ectopic p53. RNA affinity purification followed by mass spectrometry was used to identify proteins associated with LINC01021.

RESULTS

Loss of the p53-inducibility of LINC01021 resulted in an ~1.8-fold increase in the number of significantly regulated mRNAs compared to LINC01021 wild-type cells after ectopic activation of p53. A subset of direct p53 target genes, such as NOXA and FAS, displayed significantly stronger induction when the p53-inducibility of LINC01021 was abrogated. Loss of the p53-inducibility of LINC01021 resulted in alternative splicing of a small number of mRNAs, such as ARHGAP12, HSF2, and LYN. Several RNA binding proteins involved in pre-mRNA splicing were identified as interaction partners of LINC01021 by mass spectrometry.

CONCLUSIONS

Our results suggest that LINC01021 may restrict the extent and strength of p53-mediated transcriptional changes via context-dependent regulation of the expression and splicing of a subset of p53-regulated genes.

Novel Spatially Asymmetric Copper Bismuthate-Mediated Augmentation of Energy Conversion to Realize "Three-Step" Tumor Suppression

The generally undesirable bandgap and electron-hole complexation of inorganic sonosensitizers limit the efficiency of reactive oxygen species (ROS) generation, affecting the effectiveness of sonodynamic therapy (SDT). Comparatively, the novel polyvinylpyrrolidone-modified copper bismuthate (PCBO) sonosensitizers are manufactured for a "three-step" SDT promotion. In brief, first, the strong hybridization between Bi 6s and O 2p orbitals in PCBO narrows the bandgap (1.83 eV), facilitating the rapid transfer of charge carriers. Additionally, nonequivalent [CuO4]6- layers reduce crystal symmetry, confer PCBO unique piezoelectricity, and improve electron-hole separation under ultrasonic (US) excitation. This allows PCBO to convert US energy into chemical energy to produce ROS, achieving the accumulation of abundant ROS, resulting in apoptosis and tumor suppression. Concurrently, PCBO also acts as a glutathione scavenger to reduce tumor antioxidant capacity and improve efficacy. To the best of authors understanding, this study reveals PCBO as an innovative piezoelectric sonosensitizer and provides a meaningful paradigm for designing energy conversion strategies for tumor suppression.

The roles of ferroptosis in cancer: Tumor suppression, tumor microenvironment, and therapeutic interventions

In cancer treatment, the recurrent challenge of inducing apoptosis through conventional therapeutic modalities, often thwarted by therapy resistance, emphasizes the critical need to explore alternative cell death pathways. Ferroptosis, an iron-dependent form of regulated cell death triggered by the lethal accumulation of lipid peroxides on cellular membranes, has emerged as one such promising frontier in oncology. Induction of ferroptosis not only suppresses tumor growth but also holds potential for augmenting immunotherapy responses and surmounting resistance to existing cancer therapies. This review navigates the role of ferroptosis in tumor suppression. Furthermore, we delve into the complex role of ferroptosis within the tumor microenvironment and its interplay with antitumor immunity, offering insights into the prospect of targeting ferroptosis as a strategic approach in cancer therapy.

PHLDA2-mediated phosphatidic acid peroxidation triggers a distinct ferroptotic response during tumor suppression

Although the role of ferroptosis in killing tumor cells is well established, recent studies indicate that ferroptosis inducers also sabotage anti-tumor immunity by killing neutrophils and thus unexpectedly stimulate tumor growth, raising a serious issue about whether ferroptosis effectively suppresses tumor development in vivo. Through genome-wide CRISPR-Cas9 screenings, we discover a pleckstrin homology-like domain family A member 2 (PHLDA2)-mediated ferroptosis pathway that is neither ACSL4-dependent nor requires common ferroptosis inducers. PHLDA2-mediated ferroptosis acts through the peroxidation of phosphatidic acid (PA) upon high levels of reactive oxygen species (ROS). ROS-induced ferroptosis is critical for tumor growth in the absence of common ferroptosis inducers; strikingly, loss of PHLDA2 abrogates ROS-induced ferroptosis and promotes tumor growth but has no obvious effect in normal tissues in both immunodeficient and immunocompetent mouse tumor models. These data demonstrate that PHLDA2-mediated PA peroxidation triggers a distinct ferroptosis response critical for tumor suppression and reveal that PHLDA2-mediated ferroptosis occurs naturally in vivo without any treatment from ferroptosis inducers.

Multi-Enzyme Activity of MIL-101 (Fe)-Derived Cascade Nano-Enzymes for Antitumor and Antimicrobial Therapy

The clinical application of oncology therapy is hampered by high glutathione concentrations, hypoxia, and inefficient activation of cell death mechanisms in cancer cells. In this study, Fe and Mo bimetallic sulfide nanomaterial (FeS2@MoS2) based on metal-organic framework structure is rationally prepared with peroxidase (POD)-, catalase (CAT)-, superoxide dismutase (SOD)-like activities and glutathione depletion ability, which can confer versatility for treating tumors and mending wounds. In the lesion area, FeS2@MoS2 with SOD-like activity can facilitate the transformation of superoxide anions (O2 -) to hydrogen peroxide (H2O2), and then the resulting H2O2 serves as a substrate for the Fenton reaction with FMS to produce highly toxic hydroxyl radicals (∙OH). Simultaneously, FeS2@MoS2 has an ability to deplete glutathione (GSH) and catalyze the decomposition of nicotinamide adenine dinucleotide phosphate (NADPH) to curb the regeneration of GSH from the source. Thus it can realize effective tumor elimination through synergistic apoptosis-ferroptosis strategy. Based on the alteration of the H2O2 system, free radical production, glutathione depletion and the alleviation of hypoxia in the tumor microenvironment, FeS2@MoS2 NPS can not only significantly inhibit tumors in vivo and in vitro, but also inhibit multidrug-resistant bacteria and hasten wound healing. It may open the door to the development of cascade nanoplatforms for effective tumor treatment and overcoming wound infection.

In Situ Nanofiber Formation Blocks AXL and GAS6 Binding to Suppress Ovarian Cancer Development

Anexelekto (AXL) is an attractive molecular target for ovarian cancer therapy because of its important role in ovarian cancer initiation and progression. To date, several AXL inhibitors have entered clinical trials for the treatment of ovarian cancer. However, the disadvantages of low AXL affinity and severe off-target toxicity of these inhibitors limit their further clinical applications. Herein, by rational design of a nonapeptide derivative Nap-Phe-Phe-Glu-Ile-Arg-Leu-Arg-Phe-Lys (Nap-IR), a strategy of in situ nanofiber formation is proposed to suppress ovarian cancer growth. After administration, Nap-IR specifically targets overexpressed AXL on ovarian cancer cell membranes and undergoes a receptor-instructed nanoparticle-to-nanofiber transition. In vivo and in vitro experiments demonstrate that in situ formed Nap-IR nanofibers efficiently induce apoptosis of ovarian cancer cells by blocking AXL activation and disrupting subsequent downstream signaling events. Remarkably, Nap-IR can synergistically enhance the anticancer effect of cisplatin against HO8910 ovarian tumors. It is anticipated that the Nap-IR can be applied in clinical ovarian cancer therapy in the near future.

A mismatch in the expression of cell surface molecules induces tissue-intrinsic defense against aberrant cells

Tissue-intrinsic error correction enables epithelial cells to detect abnormal neighboring cells and facilitate their removal from the tissue. One of these pathways, "interface surveillance," is triggered by cells with aberrant developmental and cell-fate-patterning pathways. It remains unknown which molecular mechanisms provide cells with the ability to compare fate between neighboring cells. We demonstrate that Drosophila imaginal discs express an array of cell surface molecules previously implicated in neuronal axon guidance processes. They include members of the Robo, Teneurin, Ephrin, Toll-like, or atypical cadherin families. Importantly, a mismatch in expression levels of these cell surface molecules between adjacent cells is sufficient to induce interface surveillance, indicating that differences in expression levels between neighboring cells, rather than their absolute expression levels, are crucial. Specifically, a mismatch in Robo2 and Robo3, but not Robo1, induces enrichment of actin, myosin II, and Ena/Vasp, as well as activation of JNK and apoptosis at clonal interfaces. Moreover, Robo2 can induce interface surveillance independently of its cytosolic domain and without the need for the Robo-ligand Slit. The expression of Robo2 and other cell surface molecules, such as Teneurins or the Ephrin receptor is regulated by fate-patterning pathways intrinsic and extrinsic to the wing disc, as well as by expression of oncogenic RasV12. Combined, we demonstrate that neighboring cells respond to a mismatch in surface code patterns mediated by specific transmembrane proteins and reveal a novel function for these cell surface proteins in cell fate recognition and removal of aberrant cells during development and homeostasis of epithelial tissues.

Deficiency of factor-inhibiting HIF creates a tumor-promoting immune microenvironment

Hypoxia signaling influences tumor development through both cell-intrinsic and -extrinsic pathways. Inhibiting hypoxia-inducible factor (HIF) function has recently been approved as a cancer treatment strategy. Hence, it is important to understand how regulators of HIF may affect tumor growth under physiological conditions. Here we report that in aging mice factor-inhibiting HIF (FIH), one of the most studied negative regulators of HIF, is a haploinsufficient suppressor of spontaneous B cell lymphomas, particular pulmonary B cell lymphomas. FIH deficiency alters immune composition in aged mice and creates a tumor-supportive immune environment demonstrated in syngeneic mouse tumor models. Mechanistically, FIH-defective myeloid cells acquire tumor-supportive properties in response to signals secreted by cancer cells or produced in the tumor microenvironment with enhanced arginase expression and cytokine-directed migration. Together, these data demonstrate that under physiological conditions, FIH plays a key role in maintaining immune homeostasis and can suppress tumorigenesis through a cell-extrinsic pathway.

Nanosensors Monitor Intracellular GSH Depletion: GSH Triggers Cu(II) for Tumor Imaging and Inhibition

Glutathione (GSH) is the primary antioxidant in cells, and GSH consumption will break the redox balance in cells. Based on this, a method that uses high concentrations of GSH in the tumor microenvironment to trigger the redox reaction of Cu(II) to generate copper nanoprobes with fluorescence and tumor growth inhibition properties is proposed. The nanoprobe mainly exists in the form of Cu(I) and catalyzes the decomposition of hydrogen peroxide into hydroxyl radicals. At the same time, a simple and controllable carbon micro-nano electrode is used to construct a single-cell sensing platform, which enable the detection of glutathione content in single living cells after Cu(II) treatment, providing an excellent example for detecting single-cell biomolecules.

Smad4 sequestered in SFPQ condensates prevents TGF-β tumor-suppressive signaling

Loss of TGF-β growth-inhibitory responses is a hallmark of human cancer. However, the molecular mechanisms underlying the TGF-β resistance of cancer cells remain to be fully elucidated. Splicing factor proline- and glutamine-rich (SFPQ) is a prion-like RNA-binding protein that is frequently upregulated in human cancers. In this study, we identified SFPQ as a potent suppressor of TGF-β signaling. The ability of SFPQ to suppress TGF-β responses depends on its prion-like domain (PrLD) that drives liquid-liquid phase separation (LLPS). Mechanistically, SFPQ physically restrained Smad4 in its condensates, which excluded Smad4 from the Smad complex and chromatin occupancy and thus functionally dampened Smad-dependent transcriptional responses. Accordingly, SFPQ deficiency or loss of phase separation activities rendered human cells hypersensitive to TGF-β responses. Together, our data identify an important function of SFPQ through LLPS that suppresses Smad transcriptional activation and TGF-β tumor-suppressive activity.

Unraveling the Concealed Transcriptomic Landscape of PTEN in Human Malignancies

Background

Phosphatase and tensin homolog, widely known as PTEN, is a major negative regulator of the PI3K/AKT/mTOR signaling pathway, involved in the regulation of a variety of important cellular processes, including cell proliferation, growth, survival, and metabolism. Since most of the molecules involved in this biological pathway have been described as key regulators in cancer, the study of the corresponding genes at several levels is crucial.

Objective

Although previous studies have elucidated the physiological role of PTEN under normal conditions and its involvement in carcinogenesis and cancer progression, the transcriptional profile of PTEN has been poorly investigated.

Methods

In this study, instead of conducting the "gold-standard" direct RNA sequencing that fails to detect less abundant novel mRNAs due to the decreased sequencing depth, we designed and implemented a multiplexed PTEN-targeted sequencing approach that combined both short- and long-read sequencing.

Results

Our study has highlighted a broad spectrum of previously unknown PTEN mRNA transcripts and assessed their expression patterns in a wide range of human cancer and non-cancer cell lines, shedding light on the involvement of PTEN in cell cycle dysregulation and thus tumor development.

Conclusion

The identification of the described novel PTEN splice variants could have significant implications for understanding PTEN regulation and function, and provide new insights into PTEN biology, opening new avenues for monitoring PTEN-related diseases, including cancer.

Crucial roles of the BRCA1-BARD1 E3 ubiquitin ligase activity in homology-directed DNA repair

The tumor-suppressor breast cancer 1 (BRCA1) in complex with BRCA1-associated really interesting new gene (RING) domain 1 (BARD1) is a RING-type ubiquitin E3 ligase that modifies nucleosomal histone and other substrates. The importance of BRCA1-BARD1 E3 activity in tumor suppression remains highly controversial, mainly stemming from studying mutant ligase-deficient BRCA1-BARD1 species that we show here still retain significant ligase activity. Using full-length BRCA1-BARD1, we establish robust BRCA1-BARD1-mediated ubiquitylation with specificity, uncover multiple modes of activity modulation, and construct a truly ligase-null variant and a variant specifically impaired in targeting nucleosomal histones. Cells expressing either of these BRCA1-BARD1 separation-of-function alleles are hypersensitive to DNA-damaging agents. Furthermore, we demonstrate that BRCA1-BARD1 ligase is not only required for DNA resection during homology-directed repair (HDR) but also contributes to later stages for HDR completion. Altogether, our findings reveal crucial, previously unrecognized roles of BRCA1-BARD1 ligase activity in genome repair via HDR, settle prior controversies regarding BRCA1-BARD1 ligase functions, and catalyze new efforts to uncover substrates related to tumor suppression.

MEF2C and miR-194-5p: New Players in Triple Negative Breast Cancer Tumorigenesis

Among breast cancer (BC) subtypes, the most aggressive is triple negative BC (TNBC), which is prone to metastasis. We previously found that microRNA (miR)-194-5p is downregulated at the early stages of TNBC brain metastasis development. Additionally, the transcription factor myocyte enhancer factor 2 (MEF2)C, a bioinformatically predicted miR-194-5p target, was increasingly expressed throughout TNBC brain metastasis formation and disease severity. However, the contributions of these two players to malignant cells' features remain undetermined. This study aimed at disclosing the role of miR-194-5p and MEF2C in TNBC tumorigenesis. The transfection of 4T1 cells with a silencer for MEF2C or with a pre-miRNA for miR-194-5p was employed to study TNBC cells' phenotypic alterations regarding epithelial and mesenchymal markers, as well as migratory capability alterations. MEF2C-silenced cells presented a decline in both vimentin and cytokeratin expression, whereas the overexpression of miR-194-5p promoted an increase in cytokeratin and a reduction in vimentin, reflecting the acquisition of an epithelial phenotype. Both treatments reduced TNBC cells' migration. These results suggest that MEF2C may determine TNBC cells' invasive properties by partially determining the occurrence of epithelial-mesenchymal transition, while the overexpression of miR-194-5p promotes a decline in TNBC cells' aggressive behavior and reinforces this miRNA's role as a tumor suppressor in TNBC.

A p53/LINC00324 positive feedback loop suppresses tumor growth by counteracting SET-mediated transcriptional repression

The p53 tumor suppressor exerts antitumor functions through its ability to regulate the transcription of its downstream targets. Long noncoding RNAs (lncRNAs) act as oncogenes or tumor suppressors implicated in tumorigenesis and tumor progression. Here, we identify the lncRNA LINC00324 (long intergenic noncoding RNA 00324) as a direct p53 transcriptional target. Knockdown of LINC00324 expression promotes tumor growth by reducing p53 transcriptional activity, whereas ectopic LINC00324 expression demonstrates a reverse effect. Notably, LINC00324 is present in the endogenous p53 complex in tumor cells and directly binds to the C-terminal domain of p53 in vitro. Mechanistically, LINC00324 enables p53 transactivation by competitively disrupting the p53-SET interaction, resulting in an increase of p300/CBP-mediated H3K18 and H3K27 acetylation on the p53 target promoters. Lower LINC00324 expression is associated with more aggressive disease status and predicts worse overall survival of patients with cancer. Our study identifies a p53/LINC00324 positive feedback loop that suppresses tumor growth by counteracting SET-mediated transcriptional repression.

Molecular Mechanism Underlying the Action of a Celastrol-Loaded Layered Double Hydroxide-Coated Magnesium Alloy in Osteosarcoma Inhibition and Bone Regeneration

Osteosarcoma (OS) is a malignant bone tumor that threatens human health. Surgical removal of the tumor and followed by implantation with a graft is the golden standard for its clinical treatment. However, avoiding recurrence by enhancing the antitumor properties of the implants and improving osteogenesis around the implants remain a challenge. Here, we developed a layered double hydroxide (LDH)-coated magnesium (Mg) alloy and loaded it with celastrol. The celastrol-loaded Mg alloy exhibited enhanced corrosion resistance and sustained release of celastrol. In vitro cell culture suggested that the modified Mg alloy loaded with an appropriate amount of celastrol significantly inhibited the proliferation and migration of bone tumor cells while having little influence on normal cells. A mechanistic study revealed that the celastrol-loaded Mg alloy upregulated reactive oxygen species (ROS) generation in bone tumor cells, resulting in mitochondrial dysfunction due to reduced membrane potential, thereby inducing bone tumor cell apoptosis. Furthermore, it was found that celastrol-induced autophagy in tumor cells inhibited cell apoptosis in the initial 6 h. After ≥12 h of culture, inhibition of the PI3K-Akt-mTOR signaling pathway was noted, resulting in excessive autophagy in tumor cells, finally causing cell apoptosis. The celatsrol-loaded Mg alloy also exhibited effective antitumor properties in a subcutaneous tumor model. In vitro tartrate-resistant acid phosphatase (TRAP) staining and gene expression results revealed that the modified Mg alloy reduced the viability of osteoclasts, inducing a potential pathway for the increased bone regeneration around the modified Mg alloy seen in vivo. Together, the results of our study show that the celatsrol-loaded Mg alloy might be a promising implant for treating OS.

Regulation of VKORC1L1 is critical for p53-mediated tumor suppression through vitamin K metabolism

Here, we identified vitamin K epoxide reductase complex subunit 1 like 1 (VKORC1L1) as a potent ferroptosis repressor. VKORC1L1 protects cells from ferroptosis by generating the reduced form of vitamin K, a potent radical-trapping antioxidant, to counteract phospholipid peroxides independent of the canonical GSH/GPX4 mechanism. Notably, we found that VKORC1L1 is also a direct transcriptional target of p53. Activation of p53 induces downregulation of VKORC1L1 expression, thus sensitizing cells to ferroptosis for tumor suppression. Interestingly, a small molecular inhibitor of VKORC1L1, warfarin, is widely prescribed as an FDA-approved anticoagulant drug. Moreover, warfarin represses tumor growth by promoting ferroptosis in both immunodeficient and immunocompetent mouse models. Thus, by downregulating VKORC1L1, p53 executes the tumor suppression function by activating an important ferroptosis pathway involved in vitamin K metabolism. Our study also reveals that warfarin is a potential repurposing drug in cancer therapy, particularly for tumors with high levels of VKORC1L1 expression.

PPARγ agonist inhibits c-Myc-mediated colorectal cancer tumor immune escape

As a master transcription factor, c-Myc plays an important role in promoting tumor immune escape. In addition, PPARγ (peroxisome proliferator-activated receptor γ) regulates cell metabolism, inflammation, and tumor progression, while the effect of PPARγ on c-Myc-mediated tumor immune escape is still unclear. Here we found that cells treated with PPARγ agonist pioglitazone (PIOG) reduced c-Myc protein expression in a PPARγ-dependent manner. qPCR analysis showed that PIOG had no significant effect on c-Myc gene levels. Further analysis showed that PIOG decreased c-Myc protein half-life. Moreover, PIOG increased the binding of c-Myc to PPARγ, and induced c-Myc ubiquitination and degradation. Importantly, c-Myc increased PD-L1 and CD47 immune checkpoint protein expression and promoted tumor immune escape, while PIOG inhibited this event. These findings suggest that PPARγ agonist inhibited c-Myc-mediated tumor immune escape by inducing its ubiquitination and degradation.

A VEGFB-Based Peptidomimetic Inhibits VEGFR2-Mediated PI3K/Akt/mTOR and PLCγ/ERK Signaling and Elicits Apoptotic, Antiangiogenic, and Antitumor Activities

Vascular endothelial growth factor receptor 2 (VEGFR2) mediates VEGFA signaling mainly through the PI3K/AKT/mTOR and PLCγ/ERK1/2 pathways. Here we unveil a peptidomimetic (VGB3) based on the interaction between VEGFB and VEGFR1 that unexpectedly binds and neutralizes VEGFR2. Investigation of the cyclic and linear structures of VGB3 (named C-VGB3 and L-VGB3, respectively) using receptor binding and cell proliferation assays, molecular docking, and evaluation of antiangiogenic and antitumor activities in the 4T1 mouse mammary carcinoma tumor (MCT) model showed that loop formation is essential for peptide functionality. C-VGB3 inhibited proliferation and tubulogenesis of human umbilical vein endothelial cells (HUVECs), accounting for the abrogation of VEGFR2, p-VEGFR2 and, subsequently, PI3K/AKT/mTOR and PLCγ/ERK1/2 pathways. In 4T1 MCT cells, C-VGB3 inhibited cell proliferation, VEGFR2 expression and phosphorylation, the PI3K/AKT/mTOR pathway, FAK/Paxillin, and the epithelial-to-mesenchymal transition cascade. The apoptotic effects of C-VGB3 on HUVE and 4T1 MCT cells were inferred from annexin-PI and TUNEL staining and activation of P53, caspase-3, caspase-7, and PARP1, which mechanistically occurred through the intrinsic pathway mediated by Bcl2 family members, cytochrome c, Apaf-1 and caspase-9, and extrinsic pathway via death receptors and caspase-8. These data indicate that binding regions shared by VEGF family members may be important in developing novel pan-VEGFR inhibitors that are highly relevant in the pathogenesis of angiogenesis-related diseases.

The Structural Dynamics, Complexity of Interactions, and Functions in Cancer of Multi-SAM Containing Proteins

SAM domains are crucial mediators of diverse interactions, including those important for tumorigenesis or metastasis of cancers, and thus SAM domains can be attractive targets for developing cancer therapies. This review aims to explore the literature, especially on the recent findings of the structural dynamics, regulation, and functions of SAM domains in proteins containing more than one SAM (multi-SAM containing proteins, MSCPs). The topics here include how intrinsic disorder of some SAMs and an additional SAM domain in MSCPs increase the complexity of their interactions and oligomerization arrangements. Many similarities exist among these MSCPs, including their effects on cancer cell adhesion, migration, and metastasis. In addition, they are all involved in some types of receptor-mediated signaling and neurology-related functions or diseases, although the specific receptors and functions vary. This review also provides a simple outline of methods for studying protein domains, which may help non-structural biologists to reach out and build new collaborations to study their favorite protein domains/regions. Overall, this review aims to provide representative examples of various scenarios that may provide clues to better understand the roles of SAM domains and MSCPs in cancer in general.

The mechanism of sodium butyrate on the growth of mouse B16 melanoma cells by inhibiting the differentiation of M2-type macrophages and down-regulating the expressions of VEGF and TGF-β

Melanoma is a highly malignant cancer with a high differentiation potential and metastatic capacity. Sodium butyrate, known for its anti-cancer activity, is used in various types of solid tumors. This study aimed to investigate the effects of sodium butyrate on B16 melanoma cells using in vitro and in vivo mouse models. The study utilized MTT assay, flow cytometry, and immunoblot analysis. Mice were treated with normal saline (control) or 1 mM, 2 mM, 3 mM, or 5 mM sodium butyrate. Results showed that cell viabilities were significantly reduced in 2 mM, 3 mM, and 5 mM sodium butyrate groups after 24 to 48 hours (p < 0.01 for all). Moreover, sodium butyrate exhibited a tumor suppression effect that was time-dependent and lasted for 30 days (p < 0.01 for all). A significant tumor suppression effect was observed in the case of 5 mM sodium butyrate after 30 days (p < 0.001 for all). As compared to control (no sodium butyrate), tumor-associated macrophages were decreased in 2 mM, 3 mM, and 5 mM sodium butyrate groups (<0.01 for all). The maximum reduction was observed in 5 mM sodium butyrate groups. Sodium borate decreased the release of interleukin-10, vascular endothelial growth factor, transforming growth factor beta, and β-actin (<0.01 for all). A significant reduction was observed in the case of 5 mM concentration. Overall, these findings suggest that sodium butyrate is effective in the treatment of melanoma and may offer a promising new avenue for melanoma therapy.

Specific regulation of BACH1 by the hotspot mutant p53R175H reveals a distinct gain-of-function mechanism

Although the gain of function (GOF) of p53 mutants is well recognized, it remains unclear whether different p53 mutants share the same cofactors to induce GOFs. In a proteomic screen, we identified BACH1 as a cellular factor that recognizes the p53 DNA-binding domain depending on its mutation status. BACH1 strongly interacts with p53R175H but fails to effectively bind wild-type p53 or other hotspot mutants in vivo for functional regulation. Notably, p53R175H acts as a repressor for ferroptosis by abrogating BACH1-mediated downregulation of SLC7A11 to enhance tumor growth; conversely, p53R175H promotes BACH1-dependent tumor metastasis by upregulating expression of pro-metastatic targets. Mechanistically, p53R175H-mediated bidirectional regulation of BACH1 function is dependent on its ability to recruit the histone demethylase LSD2 to target promoters and differentially modulate transcription. These data demonstrate that BACH1 acts as a unique partner for p53R175H in executing its specific GOFs and suggest that different p53 mutants induce their GOFs through distinct mechanisms.

Potential Anti-Inflammatory and Growth Inhibitory Effect of Cyrtopodion scabrum Extract on Colon Cancer; An in vivo Study

BACKGROUND

The use of complementary and/or alternative medicine to increase the efficacy and decrease the side effects of current cancer treatment is highly required. In this in-vivo study, we aimed to investigate the anti-tumor activity and probable side effects of a natural treatment, Cyrtopodion scabrum extract (CsE), in a model of tumor bearing mice.

METHODS

We established 28 female CT26-tumor bearing balb/c-mice model. We divided them randomly into four groups (n=7): Negative control received distilled water (DW) and the three treatment groups were administered with 5-FU and two different doses (300 and 600 mg/kg) of the gecko aqueous extract, respectively. The changes in the tumor volumes and weights during and after treatment, along with the blood cell counts; spleen and thymus indices were assessed in the treatment groups. We have also measured the serum TNF-α, VEGF, AST, ALT and GSH, as well as the physical activities of the experimental mice.

RESULTS

We found that the means of tumor weights and volumes in both CsE and 5-FU treated groups were significantly lower than the untreated group (p<0.05). Serum TNF-α and VEGF levels in both CsE treated groups were remarkably lower than 5-FU and untreated groups (p<0.05). The 5-FU treatment caused a remarkably decrease in serum GSH, RBC count, WBC count, thymus index, and spleen index , while CsE treatment maintained these quantities, with no significant changes, compared to the control group. AST and ALT were not significantly changed in none of the treated groups compared to control.

CONCLUSION

Altogether, data suggest C. scabrum, as an effective and safe anti-cancer natural source, which could be used as an alternative/complementary medicine for the treatment of patients who suffer from colon cancer.

Gut Microbiome Composition and Its Metabolites Are a Key Regulating Factor for Malignant Transformation, Metastasis and Antitumor Immunity

The genetic and metabolomic abundance of the microbiome exemplifies that the microbiome comprises a more extensive set of genes than the entire human genome, which justifies the numerous metabolic and immunological interactions between the gut microbiota, macroorganisms and immune processes. These interactions have local and systemic impacts that can influence the pathological process of carcinogenesis. The latter can be promoted, enhanced or inhibited by the interactions between the microbiota and the host. This review aimed to present evidence that interactions between the host and the gut microbiota might be a significant exogenic factor for cancer predisposition. It is beyond doubt that the cross-talk between microbiota and the host cells in terms of epigenetic modifications can regulate gene expression patterns and influence cell fate in both beneficial and adverse directions for the host's health. Furthermore, bacterial metabolites could shift pro- and anti-tumor processes in one direction or another. However, the exact mechanisms behind these interactions are elusive and require large-scale omics studies to better understand and possibly discover new therapeutic approaches for cancer.

NIR Light-Mediated Mitochondrial RNA Modification for Cancer RNA Interference Therapeutics

Mitochondrial RNA (mtRNA) plays a critical role in synthesis of mitochondrial proteins. Interfering mtRNA is a highly effective way to induce cell apoptosis. Herein, we report a near-infrared (NIR) light-mediated mitochondrial RNA modification approach for long-term imaging and effective suppression of tumors. A tumor-targetable NIR fluorescent probe f-CRI consisting of a cyclic RGD peptide, a NIR fluorophore IR780, and a singlet oxygen (1O2)-labile furan group for RNA modification was rationally designed and synthesized. This probe was demonstrated to dominantly accumulate in cellular mitochondria and could be covalently conjugated onto mtRNA upon 808 nm irradiation resulting in prolonged retention in tumors. More notably, thie covalent modification of mtRNA by f-CRI could perturb the function of mitochondria leading to remarkable tumor suppression. We thus envision that our current approach would offer a potential approach for cancer RNA interference therapeutics.

The role of transcription factor Yin Yang-1 in colorectal cancer

BACKGROUND

Yin Yang-1 (YY1) is identified as a transcription factor with multiple functions. However, the role of YY1 in tumorigenesis remains controversial and its regulatory effects may depend upon not only cancer types, but also its interacting partners, chromatin structure, and the context in which it acts. It has been detected that YY1 was highly expressed in colorectal cancer (CRC). Intriguingly, many YY1-repressed genes exhibit tumor suppressive potential while YY1 silencing is related to chemotherapy resistance. Therefore, it is crucial to meticulously explore YY1 protein structure and the dynamic alteration of its interactome in each cancer type. This review attempts to describe the structure of YY1, summarize the mechanism that influence the expression level of YY1 and also highlight the recent advances in our understanding of regulatory insights of YY1 functions in CRC.

METHODS

Related studies were identified through scoping search of PubMed, Web of science, Scopus and Emhase concerning the terms of "colorectal cancer", colorectal carcinoma" or CRC with "YY1". The retrieval strategy included title, abstract, and keywords with no language limitations. All the included articles were categorized depending on the mechanisms they explored.

RESULTS

In total, 170 articles were identified for further screening. After removing the duplication, not relevant outcomes and review articles, 34 were finally included in the review. Among them, 10 articles revealed the reasons of YY1 high expression in CRC, 13 articles explored YY1 function in CRC, and 11 articles fell into both aspects. In addition, we also summarized 10 clinical trials concerning the expression and activity of YY1 in various diseases, which offers a hint for future application.

CONCLUSIONS

YY1 is highly expressed in CRC and broadly recognized as an oncogenic factor during the whole course of CRC. Sporadic controversial views are raised in term of CRC treatment, reminding us that future studies should take the influence of therapeutic regimens into concern.

A tetramerization domain in prokaryotic and eukaryotic transcription regulators homologous to p53

Transcriptional regulation usually requires the action of several proteins that either repress or activate a promotor of an open reading frame. These proteins can counteract each other, thus allowing tight regulation of the transcription of the corresponding genes, where tight repression is often linked to DNA looping or cross-linking. Here, the tetramerization domain of the bacterial gene repressor Rco from Bacillus subtilis plasmid pLS20 (Rco_pLS20) has been identified and its structure is shown to share high similarity to the tetramerization domain of the well known p53 family of human tumor suppressors, despite lacking clear sequence homology. In Rco_pLS20, this tetramerization domain is responsible for inducing DNA looping, a process that involves multiple tetramers. In accordance, it is shown that Rco_pLS20 can form octamers. This domain was named TetD_loop and its occurrence was identified in other Bacillus species. The TetD_loop fold was also found in the structure of a transcriptional repressor from Salmonella phage SPC32H. It is proposed that the TetD_loop fold has evolved through divergent evolution and that the TetD_loop originates from a common ancestor predating the occurrence of multicellular life.

A fetal tumor suppressor axis abrogates MLL-fusion-driven acute myeloid leukemia

MLL-rearrangements (MLL-r) are recurrent genetic events in acute myeloid leukemia (AML) and frequently associate with poor prognosis. In infants, MLL-r can be sufficient to drive transformation. However, despite the prenatal origin of MLL-r in these patients, congenital leukemia is very rare with transformation usually occurring postnatally. The influence of prenatal signals on leukemogenesis, such as those mediated by the fetal-specific protein LIN28B, remains controversial. Here, using a dual-transgenic mouse model that co-expresses MLL-ENL and LIN28B, we investigate the impact of LIN28B on AML. LIN28B impedes the progression of MLL-r AML through compromised leukemia-initiating cell activity and suppression of MYB signaling. Mechanistically, LIN28B directly binds to MYBBP1A mRNA, resulting in elevated protein levels of this MYB co-repressor. Functionally, overexpression of MYBBP1A phenocopies the tumor-suppressor effects of LIN28B, while its perturbation omits it. Thereby, we propose that developmentally restricted expression of LIN28B provides a layer of protection against MYB-dependent AML.

A multiplexed in vivo approach to identify driver genes in small cell lung cancer

Small cell lung cancer (SCLC) is a lethal form of lung cancer. Here, we develop a quantitative multiplexed approach on the basis of lentiviral barcoding with somatic CRISPR-Cas9-mediated genome editing to functionally investigate candidate regulators of tumor initiation and growth in genetically engineered mouse models of SCLC. We found that naphthalene pre-treatment enhances lentiviral vector-mediated SCLC initiation, enabling high multiplicity of tumor clones for analysis through high-throughput sequencing methods. Candidate drivers of SCLC identified from a meta-analysis across multiple human SCLC genomic datasets were tested using this approach, which defines both positive and detrimental impacts of inactivating 40 genes across candidate pathways on SCLC development. This analysis and subsequent validation in human SCLC cells establish TSC1 in the PI3K-AKT-mTOR pathway as a robust tumor suppressor in SCLC. This approach should illuminate drivers of SCLC, facilitate the development of precision therapies for defined SCLC genotypes, and identify therapeutic targets.

p53 engages the cGAS/STING cytosolic DNA sensing pathway for tumor suppression

Tumor suppression by TP53 involves cell-autonomous and non-cell-autonomous mechanisms. TP53 can suppress tumor growth by modulating immune system functions; however, the mechanistic basis for this activity is not well understood. We report that p53 promotes the degradation of the DNA exonuclease TREX1, resulting in cytosolic dsDNA accumulation. We demonstrate that p53 requires the ubiquitin ligase TRIM24 to induce TREX1 degradation. The cytosolic DNA accumulation resulting from TREX1 degradation activates the cytosolic DNA-sensing cGAS/STING pathway, resulting in induction of type I interferons. TREX1 overexpression sufficed to block p53 activation of the cGAS/STING pathway. p53-mediated induction of type I interferon (IFNB1) is suppressed by cGAS/STING knockout, and p53's tumor suppressor activities are compromised by the loss of signaling through the cGAS/STING pathway. Thus, our study reveals that p53 utilizes the cGAS/STING innate immune system pathway for both cell-intrinsic and cell-extrinsic tumor suppressor activities.

Ganoderic Acid A Enhances Tumor Suppression Function of Oxaliplatin via Inducing the Cytotoxicity of T Cells

BACKGROUND

Various natural products have been demonstrated for their anti-tumor activities. As a natural triterpenoid, the effects of ganoderic acid A on oxaliplatin chemotherapy for cancer treatment remain unclear.

METHODS

A xenograft mouse model of colon cancer was constructed using the HT-29 cells. Ganoderic acid A was intravenously administered with or without oxaliplatin. The CCK-8 method was performed to assess cell viability. Flow cytometry was used to determine cell apoptosis and subtyping of T cells. Cytotoxicity of the T cells was assayed using a lymphocyte-tumor co-culture system in vitro.

RESULTS

Ganoderic acid A enhanced tumor suppression of oxaliplatin in the xenograft model, while single administration showed no obvious anti-tumor effect. Ganoderic acid A didn't affect cell proliferation and apoptosis of HT-29 cells treated by oxaliplatin in vitro. Additionally, ganoderic acid A co-administered with oxaliplatin didn't impact T cell subtyping in the xenograft model. Cytotoxicity of T cells in co-administered mice was remarkably enhanced compared with oxaliplatin-treated mice.

CONCLUSION

Our findings reveal that ganoderic acid A synergistically enhances tumor suppression of oxaliplatin possibly via increasing the cytotoxicity of T cells.

The repression of oncoprotein SET by the tumor suppressor p53 reveals a p53-SET-PP2A feedback loop for cancer therapy

The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms, including the hijacking of the tumor suppressors p53 and PP2A. Targeting aberrant SET represents a promising strategy for cancer intervention. However, the mechanism by which endogenous SET is regulated in cancer cells remains largely unknown. Here, we identified the tumor suppressor p53 as a key regulator that transcriptionally repressed the expression of SET in both normal and cancer cells. In addition, p53 stimulated PP2A phosphatase activity via p53-mediated transcriptional repression of SET, whereby SET-mediated inhibition of PP2A was alleviated. Moreover, targeting the interaction between SET and PP2A catalytic subunit (PP2Ac) with FTY720 enhanced stress-induced p53 activation via PP2A-mediated dephosphorylation of p53 on threonine 55 (Thr55). Therefore, our findings uncovered a previously unknown p53-SET-PP2A regulatory feedback loop. To functionally potentiate this feedback loop, we designed a combined therapeutic strategy by simultaneously administrating a p53 activator and SET antagonist in cancer cells and observed a dramatic synergistic effect on tumor suppression. Our study reveals mechanistic insight into the regulation of the oncoprotein SET and raises a potential strategy for cancer therapy by stimulating the p53-SET-PP2A feedback loop.

Unaffected Li-Fraumeni Syndrome Carrier Parent Demonstrates Allele-Specific mRNA Stabilization of Wild-Type TP53 Compared to Affected Offspring

Li-Fraumeni Syndrome (LFS) is an autosomal dominant disorder where an oncogenic TP53 germline mutation is inherited by offspring of a carrier parent. p53 is a key tumor suppressor regulating cell cycle arrest in response to DNA damage. Unexpectedly, some mutant TP53 carriers remain unaffected, while their children develop cancer early in life. To begin unravelling this paradox, the response of dermal fibroblasts (dFb) isolated from a child with LFS was compared to those from her unaffected father after UV exposure. Phospho-Chk1[S345], a key activator of cell cycle arrest, was increased by UV induction in the LFS patient compared to their unaffected parent dFb. This result, along with previous findings of reduced CDKN1A/p21 UV induction in affected dFb, suggest that cell cycle dysregulation may contribute to cancer onset in the affected LFS subject but not the unaffected parent. Mutant p53 protein and its promoter binding affinity were also higher in dFb from the LFS patient compared to their unaffected parent. These results were as predicted based on decreased mutant TP53 allele-specific mRNA expression previously found in unaffected dFb. Investigation of the potential mechanism regulating this TP53 allele-specific expression found that, while epigenetic promoter methylation was not detectable, TP53 wild-type mRNA was specifically stabilized in the unaffected dFb. Hence, the allele-specific stabilization of wild-type TP53 mRNA may allow an unaffected parent to counteract genotoxic stress by means more characteristic of homozygous wild-type TP53 individuals than their affected offspring, providing protection from the oncogenesis associated with LFS.

Molecular links between allergy and cancer

Epidemiologic studies show both positive and negative associations between allergies and cancer. Allergic diseases may protect against tumorigenesis by promoting the immune surveillance, while carcinogenesis may be promoted through inflammatory responses from allergies. Histamine receptor antagonists are the focus of recent cancer studies because of their promising beneficial effect on tumor development. Also, cytokines, particularly IL-4 or IL-33, IgE as well as allergy-related immune cells such as eosinophils can contribute to tumor growth suppression. Depending on cancer types, cancer therapy may be more beneficial when considering combinatorial immunotherapy. In this review, we give an overview on molecular links between allergies and cancer.

Dickkopf-3: An Update on a Potential Regulator of the Tumor Microenvironment

Dickkopf-3 (Dkk-3) is a member of the Dickkopf family protein of secreted Wingless-related integration site (Wnt) antagonists that appears to modulate regulators of the host microenvironment. In contrast to the clear anti-tumorigenic effects of Dkk-3-based gene therapies, the role of endogenous Dkk-3 in cancer is context-dependent, with elevated expression associated with tumor promotion and suppression in different settings. The receptors and effectors that mediate the diverse effects of Dkk-3 have not been characterized in detail, contributing to an ongoing mystery of its mechanism of action. This review compares the various functions of Dkk-3 in the tumor microenvironment, where Dkk-3 has been found to be expressed by subpopulations of fibroblasts, endothelial, and immune cells, in addition to epithelial cells. We also discuss how the activation or inhibition of Dkk-3, depending on tumor type and context, might be used to treat different types of cancers.

CD36(+) Fibroblasts Secrete Protein Ligands That Growth-Suppress Triple-Negative Breast Cancer Cells While Elevating Adipogenic Markers for a Model of Cancer-Associated Fibroblast

Tumor and stroma coevolve to facilitate tumor growth. Hence, effective tumor therapeutics would not only induce growth suppression of tumor cells but also revert pro-tumor stroma into anti-tumoral type. Previously, we showed that coculturing triple-negative or luminal A breast cancer cells with CD36⁺ fibroblasts (FBs) in a three-dimensional extracellular matrix induced their growth suppression or phenotypic reversion, respectively. Then, we identified SLIT3, FBLN-1, and PENK as active protein ligands secreted from CD36⁺ FBs that induced growth suppression of MDA-MB-231 breast cancer cells and determined their minimum effective concentrations. Here, we have expanded our analyses to include additional triple-negative cancer cell lines, BT549 and Hs578T, as well as HCC1937 carrying a BRCA1 mutation. We show that the ectopic addition of each of the three ligands to cancer-associated fibroblasts (CAFs) elevates the expression of CD36, as well as the adipogenic marker FABP4. Lastly, we show that an agonist antibody for one of the PENK receptors induces growth suppression of all cancer cell lines tested but not for non-transformed MCF10A cells. These results clearly suggest that proteins secreted from CD36⁺ FBs induce not only growth suppression of tumor cells through binding the cognate receptors but also increasing adipogenic markers of CAFs to reprogram tumor stroma.

Myokines derived from contracting skeletal muscle suppress anabolism in MCF7 breast cancer cells by inhibiting mTOR

There is strong evidence that physical activity has a profound protective effect against multiple types of cancer. Here, we show that this effect may be mediated by factors released from skeletal muscle during simulated exercise, in situ, which suppress canonical anabolic signaling in breast cancer. We report attenuated growth of MCF7 breast cancer cells in the presence of a rodent-derived exercise conditioned perfusate, independent of prior exercise training. This reduction was concomitant with increased levels of DEPTOR protein and reduced mTOR activity.

Assessment of Early Growth Response 1 in Tumor Suppression of Esophageal Squamous Cell Carcinoma

Background: Esophageal squamous cell carcinoma (ESCC) is associated with poor survival despite surgical resection, and its pathogenesis has been broadly investigated in the past decade. Early growth response 1 (EGR-1) could involve regulating tumor development in ESCC cells. Methods: An attempt was made to examine the molecular and cellular influence of EGR-1 in esophageal cancer cells by RNA extraction, real-time PCR (qRT-PCR), cell culture, small interfering RNA (siRNA) knockdown, western blot, migration assay, and cell viability assay. One hundred and forty-four samples of ESCC were collected from our hospital and analyzed. Significantly higher EGR-1 expression was noted in tumor-adjacent normal tissue compared with tumor lesions. Results: The univariate analysis showed no significant impacts of EGR-1 expression on patients’ survival. However, after adjusting for the pathological stage, patients with EGR-1 expression > 68th percentile had lower risks of cancer-related death. Moreover, knockdown of EGR-1 significantly enhanced cell migration, invasion, and resistance to chemotherapeutic agents in two ESCC cell lines. Conclusions: EGR-1 plays a key role in tumor suppression involving tumor viability suppression and reflects the treatment effect of current chemotherapy for ESCC.

A nuclear cAMP microdomain suppresses tumor growth by Hippo pathway inactivation

Cyclic AMP (cAMP) signaling is localized to multiple spatially distinct microdomains, but the role of cAMP microdomains in cancer cell biology is poorly understood. Here, we present a tunable genetic system that allows us to activate cAMP signaling in specific microdomains. We uncover a nuclear cAMP microdomain that activates a tumor-suppressive pathway in a broad range of cancers by inhibiting YAP, a key effector protein of the Hippo pathway, inside the nucleus. We show that nuclear cAMP induces a LATS-dependent pathway leading to phosphorylation of nuclear YAP solely at serine 397 and export of YAP from the nucleus with no change in YAP protein stability. Thus, nuclear cAMP inhibition of nuclear YAP is distinct from other known mechanisms of Hippo regulation. Pharmacologic targeting of specific cAMP microdomains remains an untapped therapeutic approach for cancer; thus, drugs directed at the nuclear cAMP microdomain may provide avenues for the treatment of cancer.

Toxoplasma gondii infection possibly reverses host immunosuppression to restrain tumor growth

Tumor cells can successfully escape the host immune attack by inducing the production of immunosuppressive cells and molecules, leading to an ineffective tumor treatment and poor prognosis. Although immunotherapies have improved the survival rate of cancer patients in recent years, more effective drugs and therapies still need to be developed. As an intracellular parasite, Toxoplasma gondii can trigger a strong Th1 immune response in host cells, including upregulating the expression of interleukin-12 (IL-12) and interferon-γ (IFN-γ). Non-replicating uracil auxotrophic strains of T. gondii were used to safely reverse the immunosuppression manipulated by the tumor microenvironment. In addition to the whole lysate antigens, T. gondii-secreted effectors, including Toxoplasma profilin, rhoptry proteins (ROPs), and dense granule antigens (GRAs), are involved in arousing the host’s antigen presentation system to suppress tumors. When T. gondii infection relieves immunosuppression, tumor-related myeloid cells, including macrophages and dendritic cells (DCs), are transformed into immunostimulatory phenotypes, showing a powerful Th1 immune response mediated by CD8⁺ T cells. Afterwards, they target and kill the tumor cells, and ultimately reduce the size and weight of tumor tissues. This article reviews the latest applications of T. gondii in tumor therapy, including the activation of cellular immunity and the related signal pathways, which will help us understand why T. gondii infection can restrain tumor growth.

Near-Infrared Light-Responsive Nanoinhibitors for Tumor Suppression through Targeting and Regulating Anion Channels

The gated state of anion channels is involved in the regulation of proliferation and migration of tumors. Specific regulators are urgently needed for efficacious cancer ablation. For this purpose, it is essential to understand the molecular mechanisms of interaction between the regulators and anion channels and apply this knowledge to regulate anion channels. Transmembrane 16A (TMEM16A) is the molecular basis of the calcium-activated chloride channels. It is an anion channel activated by Ca²⁺, and the inhibition of TMEM16A is associated with a decrease in tumorigenesis. Herein, we characterized a natural compound procyanidin (PC) as an efficacious and selective inhibitor of TMEM16A with an IC₅₀ of 10.6 ± 0.6 μM. Our research revealed the precise sites (D383, R535, and E624) of electrostatic interactions between PC and TMEM16A. Near-infrared (NIR)-light-responsive photothermal conjugated polymer nanoparticles encapsulating PC (CPNs-PC) were established to remotely target and regulate the TMEM16A anion channel. Upon NIR irradiation, CPNs-PC downregulated the signaling pathway downstream of TMEM16A and arrested the cell cycle progression of cancer cells and improved the bioavailability of PC. The tumor inhibition ratio of CPNs-PC was superior to PC by 13.4%. Our findings enabled the development of a strategy to accurately and remotely regulate anion channels to promote tumor regression using NIR-light-responsive conjugated polymer nanoparticles containing specific inhibitors of TMEM16A.

Understanding the mechanistic regulation of ferroptosis in cancer: gene matters

Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases, such as tumor suppression. Though initially being found from anti-cancer drug screening and considered not essential as apoptosis for growth and development, numerous studies have demonstrated that ferroptosis is tightly regulated by key genetic pathways and/or genes, including several tumor suppressors and oncogenes. In this review, we will first introduce the basic concepts of ferroptosis, characterized by the features of non-apoptotic, iron-dependent and overwhelmed accumulation of lipid peroxides, and the underlying regulated circuits are considered to be pro-ferroptotic pathways. Then we discuss several established lipid peroxidation defending systems within cells, including SLC7A11/GPX4, FSP1/CoQ, GCH1/BH4, and mitochondria DHODH/CoQ, all of which serve as anti-ferroptoic pathways to prevent ferroptosis. Moreover, we provide a comprehensive summary of the genetic regulation of ferroptosis via targeting the above-mentioned pro-ferroptotic or anti-ferroptotic pathways. The regulation of pro- and anti-ferroptotic pathways gives rise to more specific responses to the tumor cells in a context-dependent manner, highlighting the unceasing study and deeper understanding of mechanistic regulation of ferroptosis for the purpose of applying ferroptosis induction in cancer therapy.

Comparative Pathobiology of Canine and Human Prostate Cancer: State of the Art and Future Directions

First described in 1817, prostate cancer is considered a complex neoplastic entity, and one of the main causes of death in men in the western world. In dogs, prostatic carcinoma (PC) exhibits undifferentiated morphology with different phenotypes, is hormonally independent of aggressive character, and has high rates of metastasis to different organs. Although in humans, the risk factors for tumor development are known, in dogs, this scenario is still unclear, especially regarding castration. Therefore, with the advent of molecular biology, studies were and are carried out with the aim of identifying the main molecular mechanisms and signaling pathways involved in the carcinogenesis and progression of canine PC, aiming to identify potential biomarkers for diagnosis, prognosis, and targeted treatment. However, there are extensive gaps to be filled, especially when considering the dog as experimental model for the study of this neoplasm in humans. Thus, due to the complexity of the subject, the objective of this review is to present the main pathobiological aspects of canine PC from a comparative point of view to the same neoplasm in the human species, addressing the historical context and current understanding in the scientific field.

miR‑4730 suppresses the progression of liver cancer by targeting the high mobility group A1 pathway

As liver cancer (LC) is the sixth most commonly diagnosed malignancy, it is necessary to elucidate the molecular mechanisms responsible for LC progression. MicroRNAs (miRNAs/miRs) play crucial roles in tumor progression by regulating target gene expression. The present study assessed miRNA-4730 expression and function in LC. The effects of miR-4730 overexpression were examined in LC cell lines, and the target genes of miR-4730 were evaluated using microarray analysis and TargetScan data. In addition, the association between miR-4730 expression in tissue samples and the prognosis of 70 patients with LC was evaluated. miR-4730 expression was suppressed in LC tissues and cell lines. miR-4730 overexpression suppressed cell proliferation and cell cycle progression and promoted apoptosis. High mobility group A1 (HMGA1) was revealed as the direct target of miR-4730 using luciferase reporter assay, and the inhibition of downstream integrin-linked kinase (ILK) expression and Akt or glycogen synthase kinase 3β (GSK3β) phosphorylation was confirmed. The lower expression of miR-4730 in tissue samples was significantly associated with a worse recurrence-free survival of patients with LC. On the whole, miR-4730 suppressed tumor progression by directly targeting HMGA1 and inhibiting the ILK/Akt/GSK3β pathway. miR-4730 thus has potential for use as a prognostic marker and may prove to be a therapeutic target for miRNA-based therapies.

The p53 network: cellular and systemic DNA damage responses in cancer and aging

The tumor protein TP53 gene, encoding the cellular tumor antigen p53, is the single most frequently mutated gene in human cancers. p53 plays a central role in responding to DNA damage and determines the outcome of the DNA damage checkpoint response by regulating cell cycle arrest and apoptosis. As a consequence of this function, dysfunctional p53 results in cells that, despite a damaged genome, continue to proliferate thus fueling malignant transformation. New insights have recently been gained into the complexity of the p53 regulation of the DNA damage response (DDR) and how it impacts a wide variety of cellular processes. In addition to cell-autonomous signaling mechanisms, non-cell-autonomous regulatory inputs influence p53 activity, which in turn can have systemic consequences on the organism. New inroads have also been made toward therapeutic targeting of p53 that for a long time has been anticipated.

Rapid recruitment of p53 to DNA damage sites directs DNA repair choice and integrity

Our work focuses on the critical longstanding question of the nontranscriptional role of p53 in tumor suppression. We demonstrate here that poly(ADP-ribose) polymerase (PARP)–dependent modification of p53 enables rapid recruitment of p53 to damage sites, where it in turn directs early repair pathway selection. Specifically, p53-mediated recruitment of 53BP1 at early time points promotes nonhomologous end joining over the more error-prone microhomology end-joining. Similarly, p53 directs nucleotide excision repair by mediating DDB1 recruitment. This property of p53 also correlates with tumor suppression in vivo. Our study provides mechanistic insight into how certain transcriptionally deficient p53 mutants may retain tumor-suppressive functions through regulating the DNA damage response.

p53 is primarily known as a downstream transcriptional effector in the DNA damage-response cascade. We report that endogenous p53 rapidly accumulates at DNA damage sites within 2 s of UVA microirradiation. The kinetics of p53 recruitment mimics those of known DNA damage-response proteins, such as Ku70 and poly(ADP-ribose) polymerase (PARP), and precedes recruitment of Nbs1, 53BP1, and DDB1. Mutations in the DNA-binding and C-terminal domains significantly suppress this rapid recruitment. The C-terminal domain of p53 contains key residues for PARP interaction that are required for rapid recruitment of p53 to DNA damage sites, as is PARP-dependent modification. The presence of p53 at damage sites influences the recruitment kinetics of 53BP1 and DDB1 and directs the choice of nonhomologous end joining repair (NHEJ) and nucleotide excision repair. Mutations that suppressed rapid recruitment of p53 promoted error-prone alternative end-joining (alt-NHEJ) and inhibited nucleotide excision repair. Our finding that p53 is a critical early responder to DNA damage stands in contrast with its extensively studied role as a downstream transcriptional regulator in DNA damage repair. We highlight an unrecognized role of p53 in directing DNA repair dynamics and integrity and suggest a parallel mode of p53 tumor suppression apart from its function as a transcription factor.

Cancer Chemoprevention: A Strategic Approach Using Phytochemicals

Cancer chemoprevention approaches are aimed at preventing, delaying, or suppressing tumor incidence using synthetic or natural bioactive agents. Mechanistically, chemopreventive agents also aid in mitigating cancer development, either by impeding DNA damage or by blocking the division of premalignant cells with DNA damage. Several pre-clinical studies have substantiated the benefits of using various dietary components as chemopreventives in cancer therapy. The incessant rise in the number of cancer cases globally is an issue of major concern. The excessive toxicity and chemoresistance associated with conventional chemotherapies decrease the success rates of the existent chemotherapeutic regimen, which warrants the need for an efficient and safer alternative therapeutic approach. In this scenario, chemopreventive agents have been proven to be successful in protecting the high-risk populations from cancer, which further validates chemoprevention strategy as rational and promising. Clinical studies have shown the effectiveness of this approach in managing cancers of different origins. Phytochemicals, which constitute an appreciable proportion of currently used chemotherapeutic drugs, have been tested for their chemopreventive efficacy. This review primarily aims to highlight the efficacy of phytochemicals, currently being investigated globally as chemopreventives. The clinical relevance of chemoprevention, with special emphasis on the phytochemicals, curcumin, resveratrol, tryptanthrin, kaempferol, gingerol, emodin, quercetin genistein and epigallocatechingallate, which are potential candidates due to their ability to regulate multiple survival pathways without inducing toxicity, forms the crux of this review. The majority of these phytochemicals are polyphenols and flavanoids. We have analyzed how the key molecular targets of these chemopreventives potentially counteract the key drivers of chemoresistance, causing minimum toxicity to the body. An overview of the underlying mechanism of action of these phytochemicals in regulating the key players of cancer progression and tumor suppression is discussed in this review. A summary of the clinical trials on the important phytochemicals that emerge as chemopreventives is also incorporated. We elaborate on the pre-clinical and clinical observations, pharmacokinetics, mechanism of action, and molecular targets of some of these natural products. To summarize, the scope of this review comprises of the current status, limitations, and future directions of cancer chemoprevention, emphasizing the potency of phytochemicals as effective chemopreventives.