Loss of the receptors ER, PR and HER2 promotes USP15-dependent stabilization of PARP1 in triple-negative breast cancer

In-situ injectable hydrogel for near-infrared-regulated hyperthermic perfusion therapy of triple-negative breast cancer

Hyperthermic perfusion therapy (HPT) is an emerging and effective treatment for intracavitary tumors, involving circulating a heated solution directly into body cavities such as the peritoneal or pleural spaces, targeting tumors more effectively while minimizing systemic toxicity. However, the clinical application of HPT is currently restricted to intracavitary tumors, and its efficacy is hampered by the up-regulation of thermal stress resistance genes, which enhance the thermal tolerance of cancer cells. Herein, we developed a temperature-sensitive methyl cellulose hydrogel with injectability and removability to enable targeted HPT for the triple-negative breast cancer (TNBC). Using bioinformatics screening, we identified 17-allylamino-17-demethoxygeldanamycin as a potent inhibitor and incorporated it alongside biocompatible cuttlefish ink-derived nanoparticles (CINPs), a natural photothermal agent, into the temperature-sensitive hydrogel. Under near-infrared (NIR) irradiation, CINPs mediate photothermal tumor ablation, while 17-allylamino-17-demethoxygeldanamycin reduces tumor cell resistance to hyperthermia. Moreover, the temperature-responsive phase transition of the hydrogel allows for its complete removal post-treatment, extending the scope of HPT beyond intracavitary tumors and minimizing inflammation at the injection site. This material-engineered HPT approach, achieved remarkable outcomes in both orthotopic and metastatic tumor models, inhibiting breast cancer progression and lung metastasis. These findings highlight the potential of materials-based HPT as an effective treatment for TNBC.

Bruceine A Inhibits Cell Proliferation by Targeting the USP13/PARP1 Signalling Pathway in Multiple Myeloma

Multiple myeloma (MM) is an incurable hematologic malignancy, driving significant interest in the discovery of novel therapeutic strategies. Bruceine A (BA), a tetracyclic triterpene quassinoid derived from Brucea javanica, has shown anticancer properties by modulating multiple intracellular signalling pathways and exhibiting various biological effects. However, the specific pharmacological mechanisms by which it combats MM remain unclear. In this study, we identified USP13 as a potential target of BA. We observed a significant increase in USP13 expression in patients with MM, which was strongly associated with a poorer prognosis. Furthermore, enhanced USP13 expression can stimulate MM cell proliferation both in vitro and in vivo. Mass spectrometry analysis, combined with co-immunoprecipitation and in vitro ubiquitination experiments, revealed PARP1 as a critical downstream target of USP13. USP13 can stabilize PARP1 protein through deubiquitination, promoting PARP1-mediated DNA damage repair (DDR) and facilitating MM progression. Notably, we utilized MM cell lines, an MM Patient-Derived Tumour Xenograft model, and a 5TMM3VT mouse model to determine the anticancer effects of BA on MM progression, revealing its potential to target USP13/PARP1 signalling and disrupt DDR in MM cells. In conclusion, these findings suggest that BA inhibiting USP13/PARP1-mediated DDR might be a promising therapeutic strategy for MM.

Visualization analysis of breast cancer-related ubiquitination modifications over the past two decades

BACKGROUND

Ubiquitination is a type of post-translational modification, referring to the process in which the small molecular protein ubiquitin covalently binds to target proteins under the catalysis of a series of enzymes. The process of ubiquitination is vital in the onset and progression of breast cancer. The use of the ubiquitin-protease system is expected to be a new way to treat human breast cancer. This research aimed to investigate the evolution patterns, key areas of interest, and future directions of ubiquitination in breast cancer via bibliometric analysis.

METHODS

Research articles on ubiquitination modifications in breast cancer were sourced from the Web of Science Core Collection database and analyzed via Microsoft Excel 2021, Bibliometrix, VOSviewer, and Citespace software for thorough bibliometrics.

RESULTS

From 2005-2024, 1850 English articles published in 405 journals by 1842 institutions/universities from 61 countries were included in the study. Keywords, research fields, co-cited literature and other information were included. Research on ubiquitination modifications has focused on breast cancer, expression, protein, activation, degradation, ubiquitination, phosphorylation, etc. Notably, the keywords that broke out in the past five years have focused on "triple-negative breast cancer", "promotion", and "metabolism". These findings suggest that key areas of current research are metabolism, immunity, survival, and prognosis in triple-negative breast cancer.

CONCLUSIONS

Our findings indicate that research on triple-negative breast cancer, as well as its immunological and metabolic aspects, is a burgeoning and promising area. Our work offers valuable guidance and fresh perspectives on the relationship between breast cancer and ubiquitin modification.

NOL6 Promotes Tumor Progression by Facilitating Cancer Cell-Induced Platelet Aggregation and Angiogenesis in Breast Cancer

BACKGROUND

Breast cancer (BC) is a prevalent malignancy among women, and numerous investigations have reported that platelet aggregation may play a role in BC progression. Thus, identifying new targets for BC is essential. In this regard, we focused on nucleolar protein 6 (NOL6), located on chromosome 9p13, which is implicated in tumor development.

OBJECTIVE

To investigate NOL6 expression in BC, examine its role in platelet aggregation and angiogenesis, and elucidate the underlying mechanisms.

METHODS

Bioinformatic analyses, immunoblotting, and quantitative real-time polymerase chain reaction (qPCR) were performed to assess NOL6 expression in BC. Cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were conducted to determine the impact of NOL6 on BC cell proliferation. Immunostaining, enzyme-linked immunosorbent assay (ELISA), and flow cytometry (FCM) assays were utilized to analyze the effects of NOL6 on platelet aggregation. Tube formation and transwell assays were performed to examine angiogenesis and invasion, immunoblot assays were used to confirm the underlying mechanisms, and tumor growth assays in mice were conducted to validate the findings in vivo.

RESULTS

NOL6 was found to be highly expressed in BC and was associated with patient prognosis, platelet aggregation, and angiogenesis. Its knockdown inhibited BC cell proliferation and reduced platelet aggregation induced by BC cells. Additionally, NOL6 depletion impaired angiogenesis and migration of BC cells. In vivo studies confirmed that NOL6 promotes tumor growth. Mechanistically, NOL6 enhances the Twisted spiral transcription factor 1 (Twist1)/galectin-3 axis, contributing to BC progression.

CONCLUSIONS

NOL6 can promote tumor progression by facilitating platelet aggregation and angiogenesis in BC cells through the Twist1/galectin-3 axis.

Decomposable STING nanoagonist-amplified oncolytic virotherapy through remodeling the immunosuppressive microenvironment of triple-negative breast cancer

Oncolytic viruses (OVs) are promising for cancer treatment as they specifically replicate in tumor cells. However, the systemic delivery of OVs still faces the challenges of poor tumor targeting, short circulation periods, and limited lytic efficacy. Herein, an OV-concealed targeting nanoagonist (OV-MnO2/HE) was prepared to enhance the delivery of OVs to triple-negative breast cancer (TNBC) via intravenous administration. Decomposable MnO2 biomineral shells covered the surface antigens of OVs to prevent their clearance after systemic administration. The targeting materials of HA-EGCG (HE) enhanced intratumoral accumulation via active targeting. After entering tumors, OV-MnO2/HE readily released Mn2+ and OVs, which could enhance the number of CD4+/CD8+ T cells and maturation dendritic cells (DCs) due to the synergetic effect of the STING pathway and OVs, thereby activating the immune response, resulting in the significant inhibition of TNBC growth. This work highlights the potential of the STING agonist in enhancing the antitumor efficacy of OVs and provides a potent platform for TNBC therapy.

p53 inhibits OTUD5 transcription to promote GPX4 degradation and induce ferroptosis in gastric cancer

BACKGROUND

Gastric cancer is one of the most prevalent malignant tumors within the digestive system, and ferroptosis playing a crucial role in its progression. Glutathione peroxidase 4 (GPX4), a key negative regulator of ferroptosis, is highly expressed in gastric cancer and contributes to tumor growth. Targeting the regulation of GPX4 has emerged as a promising approach to induce ferroptosis and develop effective therapy for gastric cancer.

METHODS

To confirm that OTUD5 is a deubiquitinase of GPX4 and regulates ferroptosis, we performed Western blotting, Co-IP, immunofluorescence, quantitative real-time PCR, Ub assay and flow cytometry experiments. To explore the physiological function of OUTD5, we knocked out the Otud5 gene in the mouse gastric cancer cell line (MFC) using CRISPR-Cas9 and eatablished the subcutaneous tumour model. Immunohistochemistry (IHC) analysis was used to inveatigate the pathological correlation in human gastric cancer.

RESULTS

We report that ovarian tumor domain-containing 5 (OTUD5) interacts with, deubiquitylates and stabilizes GPX4. OTUD5 depletion destabilizes GPX4, promotes lipid peroxidation and sensitizes gastric cancer cells to ferroptosis. Moreover, the p53 activator nutlin-3a suppresses OTUD5 transcription, leading to GPX4 degradation and ferroptosis of gastric cancer cells. Notably, only wild-type p53 has the capacity to inhibit OTUD5 transcription, while p53 mutations or deficiencies correlate with increased OTUD5 expression, promoting gastric cancer progression. Additionally, OTUD5 silencing and nutlin-3a-induced GPX4 degradation enhances the sensitivity of gastric cancer cells to ferroptosis in vivo. Subsequently, the p53/OTUD5/GPX4 axis is confirmed in clinical gastric cancer samples.

CONCLUSION

Collectively, these findings elucidate a mechanism whereby p53 inactivation upregulates OTUD5 transcription to deubiquitylate and stablize GPX4, resulting in ferroptosis inhibition and gastric cancer progression. This discovery highlights the potential therapeutic value of targeting OTUD5 to promote ferroptosis in p53-inactivated gastric cancer.

KEY POINTS

OTUD5 mediates GPX4 deubiquitination to regulate its stability. Deletion of OTUD5 promotes ferroptosis and inhibits tumor growth. Wild type p53 inhibits OTUD5 transcription, thereby promoting GPX4 degradation and inhibiting the development of gastric cancer. OTUD5, GPX4 expression and p53 activity are highly correlated and correlates with clinical progression in STAD.

The emerging regulatory interface between DNA repair and steroid hormone receptors in cancer

Human cells potentiate highly diverse functions through tight transcriptional regulation and maintenance of genome integrity. While the DNA damage response (DDR) safeguards the genome, ligand-activated transcription factors, such as steroid hormone receptors (SHRs), provide complex transcriptional outputs. Interestingly, an increasing body of evidence reveals a direct biological and functional interplay between DDR factors and SHR cascades in cancer. SHRs can directly affect DDR gene expression, but DDR factors in turn act as transcriptional coregulators, enabling oncogenic SHR-mediated signaling, which has the potential for novel therapeutic interventions. With a focus on breast and prostate cancer, we describe in this review recent developments in, and insights into, the complex interplay between SHR signaling and the DDR, highlighting opportunities for future clinical interventions.

Phaseolus acutifolius Recombinant Lectin Exerts Differential Proapoptotic Activity on EGFR+ and EGFR- Colon Cancer Cells and Provokes T Cell-Assisted Antitumor Responses in Mice

Background:rTBL-1, a recombinant lectin from Phaseolus acutifolius, exhibit proapoptotic activity on colon cancer cells and inhibitory properties on colon tumorigenesis in vivo. Apoptosis has been associated with a phospho-EGFR/phospho-p38/phospho-p53 mechanistic axis. Immunogenicity data have been observed in treated animals, but its possible involvement in the antitumor response remained unexplored. Objective: We investigated whether the cytotoxic activity of rTBL-1 depends on EGFR and its capacity to produce antitumor responses on syngeneic colon cancer in mice, with and without T cells, in order to explore its possible involvement in the process. Results:rTBL-1 exhibited cytotoxic effects in a concentration-dependent manner in both EGFR+ (MC-38) and EGFR- (CT-26) colon cancer cells with LC50 values of 23.50 and 30.01 µg/mL, respectively (p = 0.063). Apoptotic effects were slower and longer-lasting in MC-38 than in CT-26 cells. Significant increases in caspase-3 proteolytic activation and PARP1 cleavage were detected in both cell types, despite PARP1 rheostasis in CT-26 cells. Intralesional treatment with rTBL-1 inhibited the growth of established tumors in immunocompetent BALB/c mice in 27.81% (p = 0.0008) with a benefit in survival (p = 0.022), but not in immunodeficient BALB/c nude mice. Conclusions:rTBL-1 induces apoptosis in colon cancer cells by EGFR independent mechanisms, although its presence could be related to deeper responses. Unresponsiveness in nude mice indicated that rTBL-1 antitumor effect is the synergistic result of apoptosis induction and T cell-mediated cytotoxicity in the tumor. Future studies will focus on the immunogenic effects triggered by the antitumor activity of rTBL-1 in colon cancer.

HOXA3 activates USP15 to suppress autophagy and promote M2-type macrophage polarization in renal cell carcinoma via facilitating the deubiquitination of SQSTM1

The disease burden of renal cell carcinoma (RCC) has decreased in recent years with advances in treatment, but its pathogeny still remains elusive. We aim to study the role of homeobox A3 (HOXA3)/ubiquitin-specific peptidase 15 (USP15)/SQSTM1 axis on autophagy and M2-type macrophage polarization in RCC. In this study, cell apoptosis and proliferation were assessed by flow cytometry and CCK-8. Autolysosome fusion was observed by immunofluorescence detection of LC3 and LAMP2. The binding between HOXA3 and USP15 promoter was tested by chromatin immunoprecipitation (ChIP), EMSA, and dual-luciferase reporter assays. Also, the interaction between deubiquitinated enzyme (DUB) USP15 and SQSTM1, and ubiquitinated level of SQSTM1 were determined by co-immunoprecipitation (Co-IP) assay. Expression levels of HOXA3, USP15, C-C motif chemokine 2 (CCL2), CCL2 receptor (CCR2), M2-type macrophages, and autophagy-related markers were measured by Western blot, quantitative reverse transcription PCR (RT-qPCR), ELISA, and immunohistochemistry. Role of HOXA3/USP15 axis was verified by xenograft tumor experiment in vivo. We showed upregulated HOXA3 in RCC tissues and cells, and RCC tissues with metastasis showed higher HOXA3 level. The higher HOXA3 expression was relevant to worse overall survival in patients with RCC. HOXA3 induced RCC cell proliferation, and suppressed autophagy and apoptosis via transcriptionally activating USP15 expression. USP15 then induced deubiquitination modification of SQSTM1 in RCC cells. SQSTM1 supported M2-type macrophage polarization by inducing CCL2 secretion. HOXA3 or USP15 knockdown suppressed tumor growth and M2-type macrophage infiltration in vivo. In conclusion, HOXA3 transcriptionally activates USP15 expression, and upregulated USP15 facilitates the deubiquitination of SQSTM1 in RCC. This process on the one hand suppresses autophagy, on the other hand increases M2-type macrophage polarization through stimulating the secretion of CCL2.NEW & NOTEWORTHY We report a novel finding that highly expressed homeobox A3 (HOXA3) transcriptionally activates the expression of ubiquitin-specific peptidase 15 (USP15), resulting in the promotion of deubiquitination of SQSTM1. This process on the one hand suppresses autophagy in renal cell carcinoma (RCC), on the other hand increases M2-type macrophage polarization in the tumor microenvironment through stimulating the secretion of C-C motif chemokine 2 (CCL2).

The CYLD-PARP1 feedback loop regulates DNA damage repair and chemosensitivity in breast cancer cells

Poly(ADP-ribose) polymerase 1 (PARP1) plays a crucial role in DNA repair and genomic stability maintenance. However, the regulatory mechanisms governing PARP1 activity, particularly through deubiquitination, remain poorly elucidated. Using a deubiquitinase (DUB) library binding screen, we identified cylindromatosis (CYLD) as a bona fide DUB for PARP1 in breast cancer cells. Mechanistically, CYLD is recruited by PARP1 to DNA lesions upon genotoxic stress, where it cleaves K63-linked polyubiquitin chains on PARP1 at residues K748, K940, and K949, resulting in compromised PARP1 activation. In a reciprocal manner, PARP1 PARylates CYLD at sites E191, E231, E259, and E509, thereby enhancing its DUB activity. Consequently, depletion of CYLD leads to increased efficiency in base excision repair and confers breast cancer cells with resistance to alkylating agents. Conversely, overexpression of CYLD enhances sensitivity to PARP inhibitors (PARPi) even in homologous recombination-proficient breast cancer cells. These findings offer unique insights into the intricate interplay between CYLD and PARP1 in DNA repair, underscoring the pivotal role of targeting this regulatory axis for breast cancer chemotherapy.

Review of recent preclinical and clinical research on ligand-targeted liposomes as delivery systems in triple negative breast cancer therapy

Triple-negative breast Cancer (TNBC) is one of the deadliest types, making up about 20% of all breast cancers. Chemotherapy is the traditional manner of progressed TNBC treatment; however, it has a short-term result with a high reversibility pace. The lack of targeted treatment limited and person-dependent treatment options for those suffering from TNBC cautions to be the worst type of cancer among breast cancer patients. Consequently, appropriate treatment for this disease is considered a major clinical challenge. Therefore, various treatment methods have been developed to treat TNBC, among which chemotherapy is the most common and well-known approach recently studied. Although effective methods are chemotherapies, they are often accompanied by critical limitations, especially the lack of specific functionality. These methods lead to systematic toxicity and, ultimately, the expansion of multidrug-resistant (MDR) cancer cells. Therefore, finding novel and efficient techniques to enhance the targeting of TNBC treatment is an essential requirement. Liposomes have demonstrated that they are an effective method for drug delivery; however, among a large number of liposome-based drug delivery systems annually developed, a small number have just received authorization for clinical application. The new approaches to using liposomes target their structure with various ligands to increase therapeutic efficiency and diminish undesired side effects on various body tissues. The current study describes the most recent strategies and research associated with functionalizing the liposomes' structure with different ligands as targeted drug carriers in treating TNBCs in preclinical and clinical stages.

PRDM1 promotes the ferroptosis and immune escape of thyroid cancer by regulating USP15-mediated SELENBP1 deubiquitination

BACKGROUND

The deubiquitinating enzyme Ubiquitin-specific peptidase 15 (USP15) is upregulated in various cancers and promotes tumor progression by increasing the expression of several oncogenes. This project is designed to explore the role and mechanism of USP15 in thyroid cancer (TC) progression.

METHODS

Selenium-binding protein 1 (SELENBP1), USP15, CCL2/5, CXCL10/11, IL-4, and TGF-β1 mRNA levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR). SELENBP1, USP15, GPX4, IL-10, Arg-1, Granzyme B, TNF-α, and PR domain zinc finger protein 1 (PRDM1) protein levels were examined by western blot assay. Fe+ level, malondialdehyde (MDA), and lipid-ROS levels were determined using special kits. The proportion of CD11b+CD206+ positive cells was detected using a flow cytometry assay. The role of SELENBP1 on TC cell growth was examined using a xenograft tumor model in vivo. After GeneMANIA prediction, the interaction between USP15 and SELENBP1 was verified using Co-immunoprecipitation (CoIP) assay. The binding between PRDM1 and USP15 promoter was predicted by JASPAR and validated using Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays.

RESULTS

SELENBP1 was increased in TC subjects and cell lines, and its knockdown repressed TC cell proliferation, migration, invasion, immune escape, and induced ferroptosis in vitro, as well as blocked tumor growth in vivo. In mechanism, USP15 interacted with SELENBP1 and maintained its stabilization by removing ubiquitin. Meanwhile, the upregulation of USP15 was induced by the transcription factor PRDM1.

CONCLUSION

USP15 transcriptionally mediated by PRDM1 might boost TC cell malignant behaviors through deubiquitinating SELENBP1, providing a promising therapeutic target for TC treatment.

USP1 deubiquitinates PARP1 to regulate its trapping and PARylation activity

PARP inhibitors (PARPi) represent a game-changing treatment for patients with ovarian cancer with tumors deficient for the homologous recombination (HR) pathway treated with platinum (Pt)-based therapy. PARPi exert their cytotoxic effect by both trapping PARP1 on the damaged DNA and by restraining its enzymatic activity (PARylation). How PARP1 is recruited and trapped at the DNA damage sites and how resistance to PARPi could be overcome are still matters of investigation. Here, we described PARP1 as a substrate of the deubiquitinase USP1. At molecular level, USP1 binds PARP1 to remove its K63-linked polyubiquitination and controls PARP1 chromatin trapping and PARylation activity, regulating sensitivity to PARPi. In both Pt/PARPi-sensitive and -resistant cells, USP1/PARP1 combined blockade enhances replicative stress, DNA damage, and cell death. Our work dissected the biological interaction between USP1 and PARP1 and recommended this axis as a promising and powerful therapeutic choice for not only sensitive but also chemoresistant patients with ovarian cancer irrespective of their HR status.

SMAD4 Limits PARP1 dependent DNA Repair to Render Pancreatic Cancer Cells Sensitive to Radiotherapy

Dysregulation of SMAD4 (i.e. somatic mutation) is strongly associated with poor pancreatic ductal adenocarcinoma (PDAC) prognosis, yet the molecular mechanisms remain underlying this relationship obscure. Previously, we discovered that SMAD4 mutation renders pancreatic cancer resistant to radiotherapy via promotion of autophagy. In the current work, we observed a downregulation of the protein level of SMAD4 in PDAC as compared with adjacent normal tissue, and that such SMAD4low PDAC failed to benefit from chemotherapy. Furthermore, we observed that SMAD4 depletion dramatically enhanced DNA repair capacity in response to irradiation (IR) or a radiomimetic chemical. Interestingly, we found the radiomimetic chemical having induced a robust translocation of SMAD4 into the nucleus, where a direct interaction was shown to occur between the MH1 domain of SMAD4 and the DBD domain of PARP1. Functionally, the SMAD4-PARP1 interaction was found to perturb the recruitment of PARP1 to DNA damage sites. Accordingly, the combination of olaparib and radiotherapy was indicated in vivo and in vitro to specifically reduce the growth of SMAD4-deficient PDAC by attenuating PARP1 activity. Collectively, our results revealed a novel molecular mechanism for the involvement of the SMAD4-PARP1 interaction in DNA repair with a vital role in radiotherapy response in PDAC. Based on our set of findings, our findings offer a new combined therapeutic strategy for SMAD4 deficient PDAC that can significantly reduce pancreatic cancer radiotherapy resistance.

Discovery of dual-targeted molecules based on Olaparib and Rigosertib for triple-negative breast cancer with wild-type BRCA

PARP inhibitors (PARPis) demonstrate significant potential efficacy in the clinical treatment of BRCA-mutated triple-negative breast cancer (TNBC). However, a majority of patients with TNBC do not possess BRCA mutations, and therefore cannot benefit from PARPis. Previous studies on multi-targeted molecules derived from PARPis or disruptors of RAF-RAF pathway have offered an alternative approach to develop novel anti-TNBC agents. Hence, to broaden the application of PARP inhibitors for TNBC patients with wild-type BRCA, a series of dual-targeted molecules were constructed via integrating the key pharmacophores of Olaparib (Ola) and Rigosertib into a single entity. Subsequent studies exhibited that the resulting compounds 13a-14c obtained potential anti-proliferative activity against BRCA-defected or wild-type TNBC cells. Among them, an optimal compound 13b showed good inhibitory activity toward PARP-1, displayed approximately 34-fold higher inhibitory activity than that of Ola in MDA-MB-231 cells, and exerted multi-functional mechanisms to induce apoptosis. Moreover, 13b displayed superior antitumor efficacy (TGI, 61.3 %) than the single administration of Ola (TGI, 38.5 %), 11b (TGI, 51.8 %) or even their combined administration (TGI, 56.7 %), but did not show significant systematic toxicity. These findings suggest that 13b may serve as a potential candidate for BRCA wild-type TNBC.

Phase separation of phospho-HDAC6 drives aberrant chromatin architecture in triple-negative breast cancer

How dysregulated liquid-liquid phase separation (LLPS) contributes to the oncogenesis of female triple-negative breast cancer (TNBC) remains unknown. Here we demonstrate that phosphorylated histone deacetylase 6 (phospho-HDAC6) forms LLPS condensates in the nuclei of TNBC cells that are essential for establishing aberrant chromatin architecture. The disordered N-terminal domain and phosphorylated residue of HDAC6 facilitate effective LLPS, whereas nuclear export regions exert a negative dominant effect. Through phase-separation-based screening, we identified Nexturastat A as a specific disruptor of phospho-HDAC6 condensates, which effectively suppresses tumor growth. Mechanistically, importin-β interacts with phospho-HDAC6, promoting its translocation to the nucleus, where 14-3-3θ mediates the condensate formation. Disruption of phospho-HDAC6 LLPS re-established chromatin compartments and topologically associating domain boundaries, leading to disturbed chromatin loops. The phospho-HDAC6-induced aberrant chromatin architecture affects chromatin accessibility, histone acetylation, RNA polymerase II elongation and transcriptional profiles in TNBC. This study demonstrates phospho-HDAC6 LLPS as an emerging mechanism underlying the dysregulation of chromatin architecture in TNBC.

FANCI Inhibition Induces PARP1 Redistribution to Enhance the Efficacy of PARP Inhibitors in Breast Cancer

Breast cancer is a global public health concern with high mortality rates, necessitating the development of innovative treatment strategies. PARP inhibitors have shown efficacy in certain patient populations, but their application is largely limited to cancers with homologous recombination deficiency. Here, we identified the suppression of FANCI as a therapeutic strategy to enhance the efficacy of PARP inhibitors in breast cancer. Elevated FANCI expression in breast cancer was associated with poor prognosis and increased cell proliferation and migration. FANCI interacted with PARP1, and suppressing FANCI limited the nuclear localization and functionality of PARP1. Importantly, FANCI inhibition sensitized breast cancer cells to the PARP inhibitor talazoparib in the absence of BRCA mutations. Additionally, the CDK4/6 inhibitor palbociclib enhanced the sensitivity of breast cancer cells to talazoparib through FANCI inhibition. These findings highlight the potential of targeting FANCI to enhance the efficacy of PARP inhibitors in treating breast cancer. Significance: Targeting FANCI is a promising therapeutic strategy for enhancing PARP inhibitor sensitivity in breast cancer that holds potential for broader therapeutic applications beyond cancers harboring BRCA mutations.

Biomimetic Activation of N-Nitrosamides with Red Light-Triggered Nitric Oxide Release via Mediated Electron Transfer

Mediated electron transfer (MET) is fundamental to many biological functions, including cellular respiration, photosynthesis, and enzymatic catalysis. However, leveraging the MET process to enable the release of therapeutic gases has been largely unexplored. Herein, we report the bio-inspired activation of a series of UV-absorbing N-nitrosamide derivatives (NOA) under red light exposure, enabling the quantitative release of nitric oxide (NO) gasotransmitter via an MET process. The cornerstone of our design is the covalent linkage of a 2,4-dinitroaniline moiety, which acts as an electron mediator to the N-nitrosamide groups. This facilitates efficient electron transfer from the excited palladium(II) meso-tetraphenyltetrabenzoporphyrin (PdTPTBP) photocatalyst and the selective activation of NOA. Our approach has been validated with distinct photocatalysts and various N-nitrosamides, including those derived from carbamates, amides, and ureas. Notably, the modulation of the linker length between the electron mediator and N-nitrosamide groups serves as a regulatory mechanism for controlling NO release kinetics. Moreover, this biomimetic NO release platform demonstrates effective operation under both normoxic and hypoxic conditions, and it enables localized delivery of NO under physiological conditions, exhibiting significant anticancer efficacy within the phototherapeutic window and enhanced selectivity towards tumor cells.

The role of ubiquitination in health and disease

Ubiquitination is an enzymatic process characterized by the covalent attachment of ubiquitin to target proteins, thereby modulating their degradation, transportation, and signal transduction. By precisely regulating protein quality and quantity, ubiquitination is essential for maintaining protein homeostasis, DNA repair, cell cycle regulation, and immune responses. Nevertheless, the diversity of ubiquitin enzymes and their extensive involvement in numerous biological processes contribute to the complexity and variety of diseases resulting from their dysregulation. The ubiquitination process relies on a sophisticated enzymatic system, ubiquitin domains, and ubiquitin receptors, which collectively impart versatility to the ubiquitination pathway. The widespread presence of ubiquitin highlights its potential to induce pathological conditions. Ubiquitinated proteins are predominantly degraded through the proteasomal system, which also plays a key role in regulating protein localization and transport, as well as involvement in inflammatory pathways. This review systematically delineates the roles of ubiquitination in maintaining protein homeostasis, DNA repair, genomic stability, cell cycle regulation, cellular proliferation, and immune and inflammatory responses. Furthermore, the mechanisms by which ubiquitination is implicated in various pathologies, alongside current modulators of ubiquitination are discussed. Enhancing our comprehension of ubiquitination aims to provide novel insights into diseases involving ubiquitination and to propose innovative therapeutic strategies for clinical conditions.

SOSTDC1 Nuclear Translocation Facilitates BTIC Maintenance and CHD1-Mediated HR Repair to Promote Tumor Progression and Olaparib Resistance in TNBC

Breast tumor-initiating cells (BTICs) of triple-negative breast cancer (TNBC) tissues actively repair DNA and are resistant to treatments including chemotherapy, radiotherapy, and targeted therapy. Herein, it is found that a previously reported secreted protein, sclerostin domain containing 1 (SOSTDC1), is abundantly expressed in BTICs of TNBC cells and positively correlated with a poor patient prognosis. SOSTDC1 knockdown impairs homologous recombination (HR) repair, BTIC maintenance, and sensitized bulk cells and BTICs to Olaparib. Mechanistically, following Olaparib treatment, SOSTDC1 translocates to the nucleus in an importin-α dependent manner. Nuclear SOSTDC1 interacts with the N-terminus of the nucleoprotein, chromatin helicase DNA-binding factor (CHD1), to promote HR repair and BTIC maintenance. Furthermore, nuclear SOSTDC1 bound to β-transducin repeat-containing protein (β-TrCP) binding motifs of CHD1 is found, thereby blocking the β-TrCP-CHD1 interaction and inhibiting β-TrCP-mediated CHD1 ubiquitination and degradation. Collectively, these findings identify a novel nuclear SOSTDC1 pathway in regulating HR repair and BTIC maintenance, providing insight into the TNBC therapeutic strategies.

Proteostatic reactivation of the developmental transcription factor TBX3 drives BRAF/MAPK-mediated tumorigenesis

MAPK pathway-driven tumorigenesis, often induced by BRAFV600E, relies on epithelial dedifferentiation. However, how lineage differentiation events are reprogrammed remains unexplored. Here, we demonstrate that proteostatic reactivation of developmental factor, TBX3, accounts for BRAF/MAPK-mediated dedifferentiation and tumorigenesis. During embryonic development, BRAF/MAPK upregulates USP15 to stabilize TBX3, which orchestrates organogenesis by restraining differentiation. The USP15-TBX3 axis is reactivated during tumorigenesis, and Usp15 knockout prohibits BRAFV600E-driven tumor development in a Tbx3-dependent manner. Deleting Tbx3 or Usp15 leads to tumor redifferentiation, which parallels their overdifferentiation tendency during development, exemplified by disrupted thyroid folliculogenesis and elevated differentiation factors such as Tpo, Nis, Tg. The clinical relevance is highlighted in that both USP15 and TBX3 highly correlates with BRAFV600E signature and poor tumor prognosis. Thus, USP15 stabilized TBX3 represents a critical proteostatic mechanism downstream of BRAF/MAPK-directed developmental homeostasis and pathological transformation, supporting that tumorigenesis largely relies on epithelial dedifferentiation achieved via embryonic regulatory program reinitiation.

Comprehensive characterization of stemness-related lncRNAs in triple-negative breast cancer identified a novel prognostic signature related to treatment outcomes, immune landscape analysis and therapeutic guidance: a silico analysis with in vivo experiments

BACKGROUND

Cancer stem cells (CSCs) and long non-coding RNAs (lncRNAs) are known to play a crucial role in the growth, migration, recurrence, and drug resistance of tumor cells, particularly in triple-negative breast cancer (TNBC). This study aims to investigate stemness-related lncRNAs (SRlncRNAs) as potential prognostic indicators for TNBC patients.

METHODS

Utilizing RNA sequencing data and corresponding clinical information from the TCGA database, and employing Weighted Gene Co-expression Network Analysis (WGCNA) on TNBC mRNAsi sourced from an online database, stemness-related genes (SRGs) and SRlncRNAs were identified. A prognostic model was developed using univariate Cox and LASSO-Cox analysis based on SRlncRNAs. The performance of the model was evaluated using Kaplan-Meier analysis, ROC curves, and ROC-AUC. Additionally, the study delved into the underlying signaling pathways and immune status associated with the divergent prognoses of TNBC patients.

RESULTS

The research identified a signature of six SRlncRNAs (AC245100.6, LINC02511, AC092431.1, FRGCA, EMSLR, and MIR193BHG) for TNBC. Risk scores derived from this signature were found to correlate with the abundance of plasma cells. Furthermore, the nominated chemotherapy drugs for TNBC exhibited considerable variability between different risk score groups. RT-qPCR validation confirmed abnormal expression patterns of these SRlncRNAs in TNBC stem cells, affirming the potential of the SRlncRNAs signature as a prognostic biomarker.

CONCLUSION

The identified signature not only demonstrates predictive power in terms of patient outcomes but also provides insights into the underlying biology, signaling pathways, and immune status associated with TNBC prognosis. The findings suggest the possibility of guiding personalized treatments, including immune checkpoint gene therapy and chemotherapy strategies, based on the risk scores derived from the SRlncRNA signature. Overall, this research contributes valuable knowledge towards advancing precision medicine in the context of TNBC.

Pimpinellin ameliorates macrophage inflammation by promoting RNF146-mediated PARP1 ubiquitination

Macrophage inflammation plays a central role during the development and progression of sepsis, while the regulation of macrophages by parthanatos has been recently identified as a novel strategy for anti-inflammatory therapies. This study was designed to investigate the therapeutic potential and mechanism of pimpinellin against LPS-induced sepsis. PARP1 and PAR activation were detected by western blot or immunohistochemistry. Cell death was assessed by flow cytometry and western blot. Cell metabolism was measured with a Seahorse XFe24 extracellular flux analyzer. C57, PARP1 knockout, and PARP1 conditional knock-in mice were used in a model of sepsis caused by LPS to assess the effect of pimpinellin. Here, we found that pimpinellin can specifically inhibit LPS-induced macrophage PARP1 and PAR activation. In vitro studies showed that pimpinellin could inhibit the expression of inflammatory cytokines and signal pathway activation in macrophages by inhibiting overexpression of PARP1. In addition, pimpinellin increased the survival rate of LPS-treated mice, thereby preventing LPS-induced sepsis. Further research confirmed that LPS-induced sepsis in PARP1 overexpressing mice was attenuated by pimpinellin, and PARP1 knockdown abolished the protective effect of pimpinellin against LPS-induced sepsis. Further study found that pimpinellin can promote ubiquitin-mediated degradation of PARP1 through RNF146. This is the first study to demonstrate that pimpinellin inhibits excessive inflammatory responses by promoting the ubiquitin-mediated degradation of PARP1.

PARP1 roles in DNA repair and DNA replication: The basi(c)s of PARP inhibitor efficacy and resistance

Genome integrity is under constant insult from endogenous and exogenous sources. In order to cope, eukaryotic cells have evolved an elaborate network of DNA repair that can deal with diverse lesion types and exhibits considerable functional redundancy. PARP1 is a major sensor of DNA breaks with established and putative roles in a number of pathways within the DNA repair network, including repair of single- and double-strand breaks as well as protection of the DNA replication fork. Importantly, PARP1 is the major target of small-molecule PARP inhibitors (PARPi), which are employed in the treatment of homologous recombination (HR)-deficient tumors, as the latter are particularly susceptible to the accumulation of DNA damage due to an inability to efficiently repair highly toxic double-strand DNA breaks. The clinical success of PARPi has fostered extensive research into PARP biology, which has shed light on the involvement of PARP1 in various genomic transactions. A major goal within the field has been to understand the relationship between catalytic inhibition and PARP1 trapping. The specific consequences of inhibition and trapping on genomic stability as a basis for the cytotoxicity of PARP inhibitors remain a matter of debate. Finally, PARP inhibition is increasingly recognized for its capacity to elicit/modulate anti-tumor immunity. The clinical potential of PARP inhibition is, however, hindered by the development of resistance. Hence, extensive efforts are invested in identifying factors that promote resistance or sensitize cells to PARPi. The current review provides a summary of advances in our understanding of PARP1 biology, the mechanistic nature, and molecular consequences of PARP inhibition, as well as the mechanisms that give rise to PARPi resistance.

TKT-PARP1 axis induces radioresistance by promoting DNA double-strand break repair in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) stands as the fifth most prevalent malignant tumor on a global scale and presents as the second leading cause of cancer-related mortality. DNA damage-based radiotherapy (RT) plays a pivotal role in the treatment of HCC. Nevertheless, radioresistance remains a primary factor contributing to the failure of radiation therapy in HCC patients. In this study, we investigated the functional role of transketolase (TKT) in the repair of DNA double-strand breaks (DSBs) in HCC. Our research unveiled that TKT is involved in DSB repair, and its depletion significantly reduces both non-homologous end joining (NHEJ) and homologous recombination (HR)-mediated DSB repair. Mechanistically, TKT interacts with PARP1 in a DNA damage-dependent manner. Furthermore, TKT undergoes PARylation by PARP1, resulting in the inhibition of its enzymatic activity, and TKT can enhance the auto-PARylation of PARP1 in response to DSBs in HCC. The depletion of TKT effectively mitigates the radioresistance of HCC, both in vitro and in mouse xenograft models. Moreover, high TKT expression confers resistance of RT in clinical HCC patients, establishing TKT as a marker for assessing the response of HCC patients who received cancer RT. In summary, our findings reveal a novel mechanism by which TKT contributes to the radioresistance of HCC. Overall, we identify the TKT-PARP1 axis as a promising potential therapeutic target for improving RT outcomes in HCC.