Blocked Cell Cycle Progression Research Articles

POLQ knockdown inhibits proliferation, migration, and invasion by inducing cell cycle arrest in colorectal cancer

BackgroundPolymerase θ (POLQ) is an error-prone translesion synthesis polymerase that participates in the repair of DNA double-strand breaks. Previous studies have reported that the level of POLQ expression is distinctly upregulated in colorectal cancer (CRC), but little attention has been given to its function and regulation of CRC progression. This study aimed to explore the specific function of POLQ in CRC.MethodsQuantitative real-time PCR and western blotting analysis were used to assess the transcription and translation levels of POLQ. Then, POLQ was stably silenced using small interfering RNA in SW480 and HCT116 cells. Afterwards, the function of POLQ in CRC cells was proven via Cell Counting Kit‑8, scratch wound healing, colony formation, and Boyden chamber assays. Furthermore, we investigated the effects of POLQ on the cell cycle signaling pathway that obtained from biological pathway enrichment analysis and further verified by activating the signaling pathway.ResultsThe results showed that POLQ was highly expressed in CRC tissues and cells and was associated with poor clinical outcomes of patients. Knockdown of POLQ significantly reduced the proliferation, migration and invasion of CRC cells. Additionally, POLQ knockdown markedly decreased the expression levels of MMP2 and MMP9, and blocked cell cycle progression by inhibiting the expression of G1/M and S/M phases proteins.ConclusionsPOLQ knockdown restrained the progression of CRC by blocking the cell cycle signaling pathway.

Evodiamine inhibits proliferation and induces apoptosis of nasopharyngeal carcinoma cells via the SRC/ERBB2-mediated MAPK/ERK signaling pathway

This study aimed to investigate the effect and potential mechanism of evodiamine (EVO) on proliferation and apoptosis of nasopharyngeal carcinoma (NPC) cells. EVO inhibited proliferation, blocked cell cycle progression, and induced apoptosis of NPC cells. There are 27 known anti-NPC targets of EVO, of which eight are core targets, namely SRC, ERBB2, STAT3, MAPK8, NOS3, CXCL8, APP, and HDAC1. Molecular docking analysis showed that the binding of EVO with its key targets (SRC, ERBB2) was good. EVO also reduced the expression of SRC and ERBB2, the key proteins p-MEK and p-ERK1/2 of the MAPK/ERK signaling pathway, and the downstream proteins PCNA and XIAP. EVO inhibited the growth of NPC xenografts in nude mice and reduced the expression levels of SRC, ERBB2, ERK1/2, p-ERK1/2, PCNA and XIAP in NPC tissue. When the MAPK/ERK signaling pathway was activated by epidermal growth factor (EGF), the expression levels of PCNA and XIAP increased, the cell proliferation index increased, and the apoptosis rate decreased in the EGF + EVO treatment group compared to treatment with EVO alone. These changes indicated that the inhibitory effect of EVO on proliferation and apoptosis of NPC cells was related to the down-regulation of SRC and ERBB2 expression, and further inhibition of the MAPK/ERK signaling pathway.

Enhancing efficacy of the MEK inhibitor trametinib with paclitaxel in KRAS -mutated colorectal cancer.

KRAS is frequently mutated in the tumors of patients with metastatic colorectal cancer (mCRC) and thus represents a valid target for therapy. However, the strategies of targeting KRAS directly and targeting the downstream effector mitogen-activated protein kinase kinase (MEK) via monotherapies have shown limited efficacy. Thus, there is a strong need for novel, effective combination therapies to improve MEK-inhibitor efficacy in patients with KRAS -mutated mCRC. Our objective was to identify novel drug combinations that enhance MEK-inhibitor efficacy in patients with KRAS -mutated mCRC. In this study, we performed unbiased high-throughput screening (HTS) to identify drugs that enhance the efficacy of MEK inhibitors in vitro , and we validated the efficacy of the drugs in vivo . HTS was performed using 3-dimensional CRC spheroids. Trametinib, the anchor drug, was probed with 2 clinically ready libraries of 252 drugs to identify effective drug combinations. The effects of the drug combinations on CRC cell proliferation and apoptosis were further validated using cell growth assays, flow cytometry, and biochemical assays. Proteomic and immunostaining studies were performed to determine the effects of the drugs on molecular signaling and cell division. The effects of the drug combinations were examined in vivo using CRC patient-derived xenografts. HTS identified paclitaxel as being synergistic with trametinib. In vitro validation showed that, compared with monotherapies, this drug combination demonstrated strong inhibition of cell growth, reduced colony formation, and enhanced apoptosis in multiple KRAS -mutated CRC cell lines. Mechanistically, combining trametinib with paclitaxel led to alterations in signaling mediators that block cell cycle progression and increases in microtubule stability that resulted in significantly higher defects in the mitosis. Finally, the combination of trametinib with paclitaxel exhibited significant inhibition of tumor growth in several KRAS -mutant patient-derived xenograft mouse models. Our data provide evidence supporting clinical trials of trametinib with paclitaxel as a novel therapeutic option for patients with KRAS -mutated, metastatic CRC.

Graphene Quantum Dots Reduce Hypertrophic Scar by Inducing Myofibroblasts To Be a Quiescent State.

Contrary to the initial belief that myofibroblasts are terminally differentiated cells, myofibroblasts have now been widely recognized as an activation state that is reversible. Therefore, strategies targeting myofibroblast to be a quiescent state may be an effective way for antihypertrophic scar therapy. Graphene quantum dots (GQDs), a novel zero-dimensional and carbon-based nanomaterial, have recently garnered significant interest in nanobiomedicine, owing to their excellent biocompatibility, tunable photoluminescence, and superior physiological stability. Although multiple nanoparticles have been used to alleviate hypertrophic scars, a GQD-based therapy has not been reported. Our in vivo studies showed that GQDs exhibited significant antiscar efficacy, with scar appearance improvement, collagen reduction and rearrangement, and inhibition of myofibroblast overproliferation. Further in vitro experiments revealed that GQDs inhibited α-SMA expression, collagen synthesis, and cell proliferation and migration, inducing myofibroblasts to become quiescent fibroblasts. Mechanistic studies have demonstrated that the effect of GQDs on myofibroblast proliferation blocked cell cycle progression by disrupting the cyclin-CDK-E2F axis. This study suggests that GQDs, which promote myofibroblast-to-fibroblast transition, could be a novel antiscar nanomedicine for the treatment of hypertrophic scars and other types of pathological fibrosis.

ITGAM sustains MAPK signaling and serves as an adverse prognostic factor and therapeutic target in acute myeloid leukemia.

Acute myeloid leukemia (AML) is the second most frequently occurring type of leukemia in adults. Despite breakthroughs in genetics, the prognosis of AML patients remains dismal. The aim of this study is to find new therapeutic targets and diagnostic markers for AML and to explore their mechanisms of action. The expression patterns of integrin subunit alpha M (ITGAM) were investigated across different cell types using the Human Protein Atlas (HPA) database. The ITGAM levels across cancer types were analyzed using the Gene Expression Profiling Interactive Analysis (GEPIA) database. Prognostic correlations in AML individuals were evaluated using The Cancer Genome Atlas (TGCA) database. ITGAM-associated functions were evaluated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The AML cells were transfected with short-hairpin RNA targeting ITGAM or a control, and subsequently subjected to analysis in order to ascertain the impact of ITGAM on proliferation and apoptosis. The expression of ITGAM was significantly higher in the AML patient samples compared to the control samples. High ITGAM expression was significantly associated with poor overall survival (OS). The knockdown of ITGAM in the AML cells resulted in a decrease in proliferation and an increase in apoptosis. This was accompanied by cell cycle arrest at the G1 phase and a downregulation of protein production for cyclin D1, cyclin E1, cyclin-dependent kinase 2 (CDK2), and cyclin-dependent kinase 4 (CDK4). A pathway analysis and a western blot analysis revealed that ITGAM positively regulated mitogen-activated protein kinase (MAPK) signaling by silencing attenuated p38 MAPK (P38), c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) phosphorylation, while the total protein levels remained unchanged. ITGAM can serve as a potential prognostic biomarker and therapeutic target for AML. ITGAM production was elevated in AML and indicated poor survival. Silencing ITGAM suppressed AML cell viability and induced apoptosis by blocking cell cycle progression, likely by impeding the activation of the MAPK pathway. Further investigations that directly target the ITGAM-MAPK axis may offer novel strategies for mitigating AML pathogenesis and overcoming chemotherapy resistance.

Actinomycin D and bortezomib disrupt protein homeostasis in Wilms tumor.

Wilms tumor is the most common kidney cancer in children, and diffusely anaplastic Wilms tumor is the most chemoresistant histological subtype. Here we explore how Wilms tumor cells evade the common chemotherapeutic drug actinomycin D, which inhibits ribosomal RNA biogenesis. Using ribosome profiling, protein arrays, and a genome-wide knockout screen, we describe how actinomycin D disrupts protein homeostasis and blocks cell cycle progression. We found that, when ribosomal capacity is limited by actinomycin D treatment, anaplastic Wilms tumor cells preferentially translate proteasome components and upregulate proteasome activity. Furthermore, the proteasome inhibitor bortezomib sensitizes cells to actinomycin D treatment by inducing apoptosis both in vitro and in vivo. Lastly, we show that increased levels of proteasome components are associated with anaplastic histology and with worse prognosis in non-anaplastic Wilms tumor. In sum, maintaining protein homeostasis is critical for Wilms tumor proliferation, and it can be therapeutically disrupted by blocking protein synthesis or turnover.

Cryptolepine: A naturally derived alkaloid inhibits breast cancer progression by blocking cell cycle progression and inducing apoptosis.

e13151 Background: Triple Negative Breast cancer is an aggressive breast cancer subtype. TNBC has a more aggressive clinical course, an earlier age of beginning, a larger propensity for metastasis, and worse clinical outcomes as evidenced by a higher risk of recurrence and a shorter survival rate when compared to hormone receptor-positive or HER2-positive illness. Currently, the primary options for TNBC treatment are surgery, radiation, and chemotherapy. These treatments, however, remain ineffective due to recurrence. However, given that p53 mutations have been identified in more than 60–88% of TNBC, translating p53 into the clinical situation is particularly important in TNBC. Given the scope that some natural drugs can be used as specifically targeting prospective therapeutic in TNBC and to sensitize this aggressive malignancy while reducing side effects. In this study, we screened and evaluated the therapeutic potential of CRP in TNBC in-vitro models being an anti-malarial drug it could be repurposed as an anti-cancer therapeutic in TNBC. Moreover, the cytotoxicity activity of cryptolepine to TNBC cells and a detailed anti-tumor mechanism in mutant P53 has not been reported. Methods: MTT assays were used to examine the cytotoxicity and cell viability activity of Cryptolepine in TNBC, non-TNBC T47D and MCF-7 and non-malignant MCF10A cells. Scratch wound and clonogenic assay was used to evaluate cryptolepine’s effect on migration and colony forming ability of TNBC cells. Flow cytometry, MMP and DAPI was used to assess cell cycle arrest and cell apoptosis. The expression of proteins was detected by western blots. The differential expression of RNAs was evaluated by RT-PCR and the interaction between P53 and drug was evaluated computationally using in-silico approach and in-vitro using ChIP assay. Results: In this study, we found that cryptolepine has more preferential cytotoxicity in TNBC than non-TNBC cells. Notably, our studies revealed the mechanism that cryptolepine can induce intrinsic apoptosis and inhibit migration, colony formation ability, induce cell cycle arrest by inducing conformational change in the mutant P53 thereby increasing its DNA binding ability and also inducing its own transcriptional activation to synthesize new P53 protein and hence activating its tumor suppressing potential significantly. Conclusions: Our study revealed that CRP significantly reduced the proliferation, migration and colony forming ability of TNBC cells lines. Moreover, it was revealed that CRP induces cell cycle arrest and apoptosis by activating mutant P53 and enhancing its DNA binding ability to induce its tumor suppressing ability.

Single cell and bulk RNA expression analyses identify enhanced hexosamine biosynthetic pathway and O-GlcNAcylation in acute myeloid leukemia blasts and stem cells.

Acute myeloid leukemia (AML) is the most common acute leukemia in adults with an overall poor prognosis and high relapse rate. Multiple factors including genetic abnormalities, differentiation defects and altered cellular metabolism contribute to AML development and progression. Though the roles of oxidative phosphorylation and glycolysis are defined in AML, the role of the hexosamine biosynthetic pathway (HBP), which regulates the O-GlcNAcylation of cytoplasmic and nuclear proteins, remains poorly defined. We studied the expression of the key enzymes involved in the HBP in AML blasts and stem cells by RNA sequencing at the single-cell and bulk level. We performed flow cytometry to study OGT protein expression and global O-GlcNAcylation. We studied the functional effects of inhibiting O-GlcNAcylation on transcriptional activation in AML cells by Western blotting and real time PCR and on cell cycle by flow cytometry. We found higher expression levels of the key enzymes in the HBP in AML as compared to healthy donors in whole blood. We observed elevated O-GlcNAc Transferase (OGT) and O-GlcNAcase (OGA) expression in AML stem and bulk cells as compared to normal hematopoietic stem and progenitor cells (HSPCs). We also found that both AML bulk cells and stem cells show significantly enhanced OGT protein expression and global O-GlcNAcylation as compared to normal HSPCs, validating our in silico findings. Gene set analysis showed substantial enrichment of the NF-κB pathway in AML cells expressing high OGT levels. Inhibition of O-GlcNAcylation decreased NF-κB nuclear translocation and the expression of selected NF-κB-dependent genes controlling cell cycle. It also blocked cell cycle progression suggesting a link between enhanced O-GlcNAcylation and NF-κB activation in AML cell survival and proliferation. Our study suggests the HBP may prove a potential target, alone or in combination with other therapeutic approaches, to impact both AML blasts and stem cells. Moreover, as insufficient targeting of AML stem cells by traditional chemotherapy is thought to lead to relapse, blocking HBP and O-GlcNAcylation in AML stem cells may represent a novel promising target to control relapse.

Abstract 2874: Cancer metabolism in radiation resistance: Complementary roles of O-GlcNAc transferase and PARP1

Abstract The efficacy of image-guided radiotherapy (RT) has been linked to directing increased chromosomal double strand breaks (DSBs) to tumor cells while sparing surrounding normal tissue. DSBs can block cell cycle progression and promote mitotic catastrophe, cell death and senescence. End processing of persistent DSBs releases single strand DNA (ssDNA), driving cGAS/STING signaling and anti-tumor immune response. DSB repair, whether by non-homologous end-joining (NHEJ) or homologous recombination (HR), is a resistance mechanism, supporting cell survival, repopulation and immune evasion. Decades of effort to block DSB repair to enhance benefits of RT has yet to produce approved agents. Toxicity due to lack of cancer specificity may prevent the current generation of targeted agents from reaching the clinic. An answer may come from examining cancer metabolic reprogramming as a determinant of intrinsic radiation resistance. Along with other glucose metabolites, the Warburg effect increases N-acetyl glucosamine (GlcNAc) biosynthesis, which not only supports N-glycosylation but also modification of nucleocytoplasmic proteins by O-GlcNAc transferase (OGT). OGT-dependent O-GlcNAcylation confers radiation resistance, in part by accelerating DSB repair. OGT regulates γH2AX, 53BP1 and BRCA1 foci kinetics and suppresses ssDNA formation at DSB ends, limiting HR but favoring NHEJ for S/G2 DSB repair. Blocking OGT induces radiation sensitization in vitro and in vivo. In cells, OGT inhibition results in hyperresection, persistent RPA and RAD51 foci and accumulation of cytosolic DNA. One mediator may be the histone methyltransferase EZH2, which is rapidly recruited to deposit H3K27me3 at DSBs, promoting NHEJ repair. Irradiation of EZH2 KO cells results in hyperresection that cannot be suppressed by O-GlcNAcylation. Cancer cells may also accumulate NAD+, a substrate for PARP1 incorporated into poly-ADP-ribose to initiate DSB repair. Much like OGT inhibition, blocking PARP1 induces hyperresection and shifts repair toward HR and away from NHEJ. Importantly, increasing O-GlcNAcylation can suppress ssDNA formation even in PARP1 KO cells. In turn, inhibiting PARP1 enhances hyperesection in EZH2 KO cells, leading to a marked increase in cytosolic ssDNA. Our data assign complementary roles for EZH2 and PARP1 in DSB repair pathway choice by independently limiting 5' end resection. This directs DSBs to rapid, imprecise repair by NHEJ over slow and precise repair by HR. An implication is that PARP inhibitor resistance due to the Warburg effect may be mediated by EZH2. Driving hyperresection by targeting O-GlcNAcylation or H3K27 trimethylation along with PARP inhibition may saturate the capacity of HR and produce irreversible damage in cancer cells. Targeting impacts of metabolic reprogramming on DSB repair may not only enhance the therapeutic index of radiation but also sharpen synthetic lethality with HR deficiency. Citation Format: Elena E. Efimova, Sera Averbek, Donald J. Wolfgeher, Ding Wu, Yue Liu, Stephen J. Kron. Cancer metabolism in radiation resistance: Complementary roles of O-GlcNAc transferase and PARP1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2874.

Abstract 5703: Development of RVL-101, a CDK4/6-selective, small molecule inhibitor with superior CNS penetration and combinability potential for the effective treatment of primary and metastatic brain tumors

Abstract Cyclin-dependent kinases 4 and 6 (CDK4/6) are key regulators of the cell cycle that are frequently dysregulated in cancer, leading to unchecked cell growth. CDK4/6 inhibitors have emerged as a promising class of anticancer agents that selectively target this pathway. The primary mode of action of CDK4/6 inhibitors relies on the disruption of retinoblastoma (Rb) protein phosphorylation, which thereby blocks cell cycle progression from G1 to S phase and reduces proliferation of cancer cells by a cytostatic mechanism. However, despite their efficacy, approved and clinical-stage CDK4/6 inhibitors have modest penetration of unbound drug into the brain, limiting their utility in the treatment of brain metastases and primary brain tumors. Additionally, despite the potential benefits of CDK4/6 inhibitors as combination therapies with cytotoxic agents, adjunctive treatment options remain underexplored due to the poor safety profiles of existing therapies. RVL-101 is a preclinical, investigational drug with a novel pharmacophore that has a low nanomolar activity against CDK4, is CDK2,6,7,9-sparing, and maintains >500-fold selectivity over CDK1. To maximize the potential of RVL-101 as a preferred combination partner, this novel agent has been engineered to have exquisite kinome- and safety-panel selectivity with no measured CYP inhibition or induction liabilities. RVL-101 is differentiated from approved and clinical stage CDK4/6 inhibitors having both high partitioning into the brain (Kp) and high free-brain (Kpu,u = 0.7) levels resulting in equal levels of unbound drug in all relevant compartments at steady state. Like other CDK4/6 agents, RVL-101 is broadly efficacious in vivo in ER+/HER2- xenograft models at well-tolerated doses. However, RVL-101 has also demonstrated robust activity in HR-/HER2+ xenograft models as a single-agent and has uniquely shown improved tumor inhibition effect in combination with approved HER2 cytotoxic therapeutics tucatinib and fam-trastuzumab-deruxtecan. RVL-101 was also tested in a GBM model as a monotherapy and in conjunction with the cytotoxic agent temozolomide (TMZ). Remarkably, QD dosing of the cytostatic agent, RVL-101, after pulsatile pretreatment with TMZ led to dramatic synergistic efficacy compared to either agent alone, leading to 100% survival of all animals on the dual therapy arm for more than 3 weeks post discontinuation of dosing. RVL-101 offers the combination of substantial therapeutic benefit and consistent free-drug levels in plasma and CNS that could lead to safe and effective treatment for a broader patient population. Citation Format: John E. Campbell, Bo-Sheng Pan, Michael Bower, Peter Bertinato, Nisha Perez, Victoria Gras Andreu, Neha Rana, Sophia Tabchouri, Ankit Gupta, Jonah Kallenbach. Development of RVL-101, a CDK4/6-selective, small molecule inhibitor with superior CNS penetration and combinability potential for the effective treatment of primary and metastatic brain tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5703.

Abstract 4549: Combinations of ciclopirox olamine and metformin exert synergistic antitumor activity in triple-negative breast cancer

Abstract Introduction: Triple-negative breast cancer (TNBC) represents a challenging subtype of breast cancer because of its limited treatment options. Recent research has highlighted the potential benefits of combining pharmacological agents to enhance therapeutic outcomes. Studies show that Ciclopirox olamine (CPX), an off-patent anti-fungal drug, induces cell cycle G1-phase arrest and activates the intrinsic apoptosis pathway by downregulating the anti-apoptotic proteins. Meanwhile, metformin, a safe and first-line drug for the treatment of type II diabetes, has been shown to induce cell cycle S-phase arrest and activates the extrinsic apoptosis pathway via induction of endogenous TRAIL in TNBC cells. However, whether the combinations of CPX and metformin would exert potent antitumor activity against TNBC remains unclear. Methods: Cell proliferation (MTS) assays and LIVE/DEAD cell imaging were used to determine the combined inhibitory effects on TNBC cells. IC50s and the combination index (CI) were calculated. Flow cytometry assays were carried out to analyze if the combinations are more potent to block cell cycle progression. Apoptotic-specific ELISA and flow cytometry analysis of Annexin V-PI staining were performed to assess if the combinations are significantly more effective to induce apoptosis. Western blot assays were used to examine if the combinations markedly induced the expression of TRAIL and cleavages of PARP and caspases. Tumor xenograft models will be established to test the in vivo antitumor activity of CPX and metformin either alone or in combinations. Results: Data indicated that both CPX and metformin independently inhibited the proliferation of TNBC cells. A synergistic effect was observed when CPX and metformin were used in combination, resulting in a more potent inhibition of TNBC cell proliferation. The combinatorial treatment effectively suppressed colony formation of TNBC cells. Synergy between CPX and metformin was partially linked to the enhanced activation of the AMPK-mTOR pathway, as the combination significantly enhanced the phosphorylation of AMPKα. The combinations also induced enhanced apoptosis in TNBC cells through both the intrinsic and extrinsic pathways. The combinatorial effects of CPX and metformin on in vivo tumor growth are under investigation. Conclusions: Combinations of CPX and metformin show synergistic effects on inhibiting TNBC cell proliferation. Our studies suggest a potential therapeutic strategy for TNBC, with the combinations of these agents exhibiting an enhanced antitumor activity. Further investigation is warranted to validate the results and explore their clinical applications. Key words: Triple-negative breast cancer, Ciclopirox olamine, Metformin, Combination, Apoptosis Citation Format: Yakun Wu, Hui Lyu, Congcong Tan, Margaret E. Larsen, Shile Huang, Bolin Liu. Combinations of ciclopirox olamine and metformin exert synergistic antitumor activity in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4549.

Potential application of Nardostachyos Radix et Rhizoma-Rhubarb for the treatment of diabetic kidney disease based on network pharmacology and cell culture experimental verification.

Diabetic kidney disease (DKD) is one of the serious complications of diabetes mellitus, and the existing treatments cannot meet the needs of today's patients. Traditional Chinese medicine has been validated for its efficacy in DKD after many years of clinical application. However, the specific mechanism by which it works is still unclear. Elucidating the molecular mechanism of the Nardostachyos Radix et Rhizoma-rhubarb drug pair (NRDP) for the treatment of DKD will provide a new way of thinking for the research and development of new drugs. To investigate the mechanism of the NRDP in DKD by network pharmacology combined with molecular docking, and then verify the initial findings by in vitro experiments. The Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to screen active ingredient targets of NRDP. Targets for DKD were obtained based on the Genecards, OMIM, and TTD databases. The VENNY 2.1 database was used to obtain DKD and NRDP intersection targets and their Venn diagram, and Cytoscape 3.9.0 was used to build a "drug-component-target-disease" network. The String database was used to construct protein interaction networks. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and Gene Ontology analysis were performed based on the DAVID database. After selecting the targets and the active ingredients, Autodock software was used to perform molecular docking. In experimental validation using renal tubular epithelial cells (TCMK-1), we used the Cell Counting Kit-8 assay to detect the effect of NRDP on cell viability, with glucose solution used to mimic a hyperglycemic environment. Flow cytometry was used to detect the cell cycle progression and apoptosis. Western blot was used to detect the protein expression of STAT3, p-STAT3, BAX, BCL-2, Caspase9, and Caspase3. A total of 10 active ingredients and 85 targets with 111 disease-related signaling pathways were obtained for NRDP. Enrichment analysis of KEGG pathways was performed to determine advanced glycation end products (AGEs)-receptor for AGEs (RAGE) signaling as the core pathway. Molecular docking showed good binding between each active ingredient and its core targets. In vitro experiments showed that NRDP inhibited the viability of TCMK-1 cells, blocked cell cycle progression in the G0/G1 phase, and reduced apoptosis in a concentration-dependent manner. Based on the results of Western blot analysis, NRDP differentially downregulated p-STAT3, BAX, Caspase3, and Caspase9 protein levels (P < 0.01 or P < 0.05). In addition, BAX/BCL-2 and p-STAT3/STAT3 ratios were reduced, while BCL-2 and STAT3 protein expression was upregulated (P < 0.01). NRDP may upregulate BCL-2 and STAT3 protein expression, and downregulate BAX, Caspase3, and Caspase9 protein expression, thus activating the AGE-RAGE signaling pathway, inhibiting the vitality of TCMK-1 cells, reducing their apoptosis. and arresting them in the G0/G1 phase to protect them from damage by high glucose.

DHODH inhibition represents a therapeutic strategy and improves abiraterone treatment in castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) is an aggressive disease with poor prognosis, and there is an urgent need for more effective therapeutic targets to address this challenge. Here, we showed that dihydroorotate dehydrogenase (DHODH), an enzyme crucial in the pyrimidine biosynthesis pathway, is a promising therapeutic target for CRPC. The transcript levels of DHODH were significantly elevated in prostate tumors and were negatively correlated with the prognosis of patients with prostate cancer. DHODH inhibition effectively suppressed CRPC progression by blocking cell cycle progression and inducing apoptosis. Notably, treatment with DHODH inhibitor BAY2402234 activated androgen biosynthesis signaling in CRPC cells. However, the combination treatment with BAY2402234 and abiraterone decreased intratumoral testosterone levels and induced apoptosis, which inhibited the growth of CWR22Rv1 xenograft tumors and patient-derived xenograft organoids. Taken together, these results establish DHODH as a key player in CRPC and as a potential therapeutic target for advanced prostate cancer.

PR55α-controlled protein phosphatase 2A inhibits p16 expression and blocks cellular senescence induction by γ-irradiation.

Cellular senescence is a permanent cell cycle arrest that can be triggered by both internal and external genotoxic stressors, such as telomere dysfunction and DNA damage. The execution of senescence is mainly by two pathways, p16/RB and p53/p21, which lead to CDK4/6 inhibition and RB activation to block cell cycle progression. While the regulation of p53/p21 signaling in response to DNA damage and other insults is well-defined, the regulation of the p16/RB pathway in response to various stressors remains poorly understood. Here, we report a novel function of PR55α, a regulatory subunit of PP2A Ser/Thr phosphatase, as a potent inhibitor of p16 expression and senescence induction by ionizing radiation (IR), such as γ-rays. The results show that ectopic PR55α expression in normal pancreatic cells inhibits p16 transcription, increases RB phosphorylation, and blocks IR-induced senescence. Conversely, PR55α-knockdown by shRNA in pancreatic cancer cells elevates p16 transcription, reduces RB phosphorylation, and triggers senescence induction after IR. Furthermore, this PR55α function in the regulation of p16 and senescence is p53-independent because it was unaffected by the mutational status of p53. Moreover, PR55α only affects p16 expression but not p14 (ARF) expression, which is also transcribed from the same CDKN2A locus but from an alternative promoter. In normal human tissues, levels of p16 and PR55α proteins were inversely correlated and mutually exclusive. Collectively, these results describe a novel function of PR55α/PP2A in blocking p16/RB signaling and IR-induced cellular senescence.

Broccoli extracellular vesicles enhance the therapeutic effects and restore the chemosensitivity of 5-fluorouracil on colon cancer

Broccoli contains an amount of biologically active substances, which bring beneficial effects on human health. Plant extracellular vesicles have been shown to be novel key factors in cancer diagnosis and tumor therapy. To date, the challenge of overcoming chemoresistance to 5-fluorouracil (5-FU) to facilitate the clinical management of colorectal cancer (CRC) has not been successful. Nevertheless, the functions of broccoli extracellular vesicles (BEVs) in the progression of CRC and 5-FU resistance are predominantly unclear. Herein, we showed that BEVs isolated from broccoli juice were effectively taken up by colorectal cancer HT-29 cells. The co-administration of BEVs and 5-FU significantly inhibited the proliferation and migration of colorectal cancer HT-29 cells, effectively blocking cell cycle progression. Furthermore, the co-administration of BEVs and 5-FU induced apoptosis by stimulating ROS production and disrupting mitochondrial function. Importantly, we found that BEVs reversed 5-FU resistance in HT-29 cells by suppressing the abnormal activation of the PI3K/Akt/mTOR signaling pathway. Collectively, our findings represent a novel strategy for utilizing BEVs to improve the efficacy of colorectal cancer treatment and enhance 5-FU chemosensitivity.

Myb overexpression synergizes with the loss of Pten and is a dependency factor and therapeutic target in T-cell lymphoblastic leukemia.

T-lineage acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that accounts for 10%-15% of pediatric and 25% of adult ALL cases. Although the prognosis of T-ALL has improved over time, the outcome of T-ALL patients with primary resistant or relapsed leukemia remains poor. Therefore, further progress in the treatment of T-ALL requires a better understanding of its biology and the development of more effective precision oncologic therapies. The proto-oncogene MYB is highly expressed in diverse hematologic malignancies, including T-ALLs with genomic aberrations that further potentiate its expression and activity. Previous studies have associated MYB with a malignant role in the pathogenesis of several cancers. However, its role in the induction and maintenance of T-ALL remains relatively poorly understood. In this study, we found that an increased copy number of MYB is associated with higher MYB expression levels, and might be associated with inferior event-free survival of pediatric T-ALL patients. Using our previously described conditional Myb overexpression mice, we generated two distinct MYB-driven T-ALL mouse models. We demonstrated that the overexpression of Myb synergizes with Pten deletion but not with the overexpression of Lmo2to accelerate the development of T-cell lymphoblastic leukemias. We also showed that MYB is a dependency factor in T-ALL since RNA interference of Myb blocked cell cycle progression and induced apoptosis in both human and murine T-ALL cell lines. Finally, we provide preclinical evidence that targeting the transcriptional activity of MYB can be a useful therapeutic strategy for the treatment of T-ALL.

AF1q is a universal marker of neuroblastoma that sustains N-Myc expression and drives tumorigenesis

Neuroblastoma is the most common extracranial malignant tumor of childhood, accounting for 15% of all pediatric cancer deaths. Despite significant advances in our understanding of neuroblastoma biology, five-year survival rates for high-risk disease remain less than 50%, highlighting the importance of identifying novel therapeutic targets to combat the disease. MYCN amplification is the most frequent and predictive molecular aberration correlating with poor outcome in neuroblastoma. N-Myc is a short-lived protein primarily due to its rapid proteasomal degradation, a potentially exploitable vulnerability in neuroblastoma. AF1q is an oncoprotein with established roles in leukemia and solid tumor progression. It is normally expressed in brain and sympathetic neurons and has been postulated to play a part in neural differentiation. However, no role for AF1q in tumors of neural origin has been reported. In this study, we found AF1q to be a universal marker of neuroblastoma tumors. Silencing AF1q in neuroblastoma cells caused proteasomal degradation of N-Myc through Ras/ERK and AKT/GSK3β pathways, activated p53 and blocked cell cycle progression, culminating in cell death via the intrinsic apoptotic pathway. Moreover, silencing AF1q attenuated neuroblastoma tumorigenicity in vivo signifying AF1q’s importance in neuroblastoma oncogenesis. Our findings reveal AF1q to be a novel regulator of N-Myc and potential therapeutic target in neuroblastoma.

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells

The CDK4/6 inhibitor palbociclib blocks cell cycle progression in Estrogen receptor-positive, human epidermal growth factor 2 receptor-negative (ER+/HER2-) breast tumor cells. Despite the drug's success in improving patient outcomes, a small percentage of tumor cells continues to divide in the presence of palbociclib-a phenomenon we refer to as fractional resistance. It is critical to understand the cellular mechanisms underlying fractional resistance because the precise percentage of resistant cells in patient tissue is a strong predictor of clinical outcomes. Here, we hypothesize that fractional resistance arises from cell-to-cell differences in core cell cycle regulators that allow a subset of cells to escape CDK4/6 inhibitor therapy. We used multiplex, single-cell imaging to identify fractionally resistant cells in both cultured and primary breast tumor samples resected from patients. Resistant cells showed premature accumulation of multiple G1 regulators including E2F1, retinoblastoma protein, and CDK2, as well as enhanced sensitivity to pharmacological inhibition of CDK2 activity. Using trajectory inference approaches, we show how plasticity among cell cycle regulators gives rise to alternate cell cycle "paths" that allow individual tumor cells to escape palbociclib treatment. Understanding drivers of cell cycle plasticity, and how to eliminate resistant cell cycle paths, could lead to improved cancer therapies targeting fractionally resistant cells to improve patient outcomes.

Transforming Growth Factor-β/Smad Signaling Inhibits Melanoma Cancer Stem Cell Self-Renewal, Tumor Formation and Metastasis.

The secreted protein transforming growth factor-beta (TGFβ) plays essential roles, ranging from cell growth regulation and cell differentiation in both normal and cancer cells. In melanoma, TGFβ acts as a potent tumor suppressor in melanoma by blocking cell cycle progression and inducing apoptosis. In the present study, we found TGFβ to regulate cancer stemness in melanoma through the Smad signaling pathway. We discovered that TGFβ/Smad signaling inhibits melanosphere formation in multiple melanoma cell lines and reduces expression of the CD133+ cancer stem cell subpopulation in a Smad3-dependent manner. Using preclinical models of melanoma, we further showed that preventing Smad3/4 signaling, by means of CRISPR knockouts, promoted both tumorigenesis and lung metastasis in vivo. Collectively, our results define new functions for the TGFβ/Smad signaling axis in melanoma stem-cell maintenance and open avenues for new therapeutic approaches to this disease.

Resveratrol protects mesangial cells under high glucose by regulating the miR-1231/IGF1/ERK pathway.

Diabetic nephropathy (DN) is one of the complications of diabetes mellitus and the main cause of end-stage renal disease (ESRD), which is a serious threat to human health. In DN, mesangial cells (MCs) are a critical target cell that perform a variety of key functions, and abnormal proliferation of MCs is a common and prominent pathological change in DN. In recent years, the investigation of Chinese medicine interventions for DN has increased significantly in recent years due to the many potential adverse effects and controversies associated with the treatment of DN with Western medicines. In this study, we evaluated the protective effect of resveratrol (RES), an active ingredient known as a natural antioxidant, on HMCs under high glucose and explored its possible mechanism of action. We found that RES inhibited the proliferation of human mesangial cell (HMC) under high glucose and blocked cell cycle progression. In the high glucose environment, RES upregulated miR-1231, reduced IGF1 expression, inhibited the activity of the extracellular signal-regulated kinase (ERK) signaling pathway and reduced levels of the inflammatory factors TNF-α and IL-6. In addition, we found that miR-1231 mimics were synergistically inhibited with RES, whereas miR-1231 inhibitor attenuated the protective effect of RES on HMCs. Thus, our results suggest that the protective effect of RES on HMCs under high glucose is achieved, at least in part, through modulation of the miR-1231/IGF1/ERK pathway. The discovery of this potential mechanism may provide a new molecular therapeutic target for the prevention and treatment of DN, and may also bring new ideas for the clinical research in DN.