Phosphorylated RB Promotes Cancer Immunity by Inhibiting NF-κB Activation and PD-L1 Expression

Targeting BATF2-RGS2 axis reduces T-cell exhaustion and restores anti-tumor immunity

OBJECTIVE

This study aims to investigate the role of RGS2 in immune regulation in lung cancer (LC) and explore the regulatory relationship between RGS2 and BATF2 in modulating T cell exhaustion and tumor immune evasion.

METHODS

Single-cell transcriptome-based analysis was performed to identify CD8+ T-cell profiles and regulatory factors in six LC patients receiving neoadjuvant PD-1 blockade therapy. Mouse 3LL cells or murine tumor organoid models were transplanted into wild-type, RGS2 knock-out (RGS2-/-), or BATF2 knock-out (BATF2-/-) mice to analyze the effects of RGS2 and BATF2 on tumor growth, metastasis, and immune cell infiltration. CD8+ from these mice were isolated and co-cultured with cancer cells to analyze T cell cytotoxicity in vitro. The transcriptional regulation of RGS2 by BATF2 was analyzed using luciferase reporter assays.

RESULTS

RGS2 was highly expressed in CD8+ T-exhausted (Tex) cells and was associated with pro-inflammatory pathways. High RGS2 expression predicted poor clinical outcomes and limited response to PD-1/PD-L1 blockade therapy. In RGS2-/- mice, tumor metastasis and angiogenesis were suppressed, CD8+ effector T cells were enhanced, and T cell exhaustion markers were reduced. BATF2 was identified as a key transcriptional regulator of RGS2, promoting T cell exhaustion through inhibition of CXCL13 secretion. Knockdown of BATF2 or RGS2 impaired lung cancer cell proliferation and enhanced sensitivity to NK cell-mediated cytotoxicity in vitro. In BATF2-/- mice, the populations of immune active CD8+ T cells were increased, while exhausted T cells were reduced, leading to improved anti-tumor immune responses.

CONCLUSIONS

RGS2, regulated by BATF2, plays a critical role in driving T cell exhaustion and tumor immune evasion in LC. Targeting the BATF2-RGS2 axis may enhance the effectiveness of immunotherapy by reversing T cell exhaustion and improving anti-tumor immunity.

Synergistic targeting strategies for prostate cancer

Prostate cancer is the second most commonly diagnosed cancer and the fifth leading cause of death among men worldwide. Androgen deprivation therapy is a common prostate cancer treatment, but its efficacy is often hindered by the development of resistance, which results in reducing survival benefits. Immunotherapy showed great promise in treating solid tumours; however, clinically significant improvements have not been demonstrated for patients with prostate cancer, highlighting specific drawbacks of this therapeutic modality. Hence, exploring novel strategies to synergistically enhance the efficacy of prostate cancer immunotherapy is imperative. Clinical investigations have focused on the combined use of targeted or gene therapy and immunotherapy for prostate cancer. Notably, tumour-specific antigens and inflammatory mediators are released from tumour cells after targeted or gene therapy, and the recruitment and infiltration of immune cells, including CD8+ T cells and natural killer cells activated by immunotherapy, are further augmented, markedly improving the efficacy and prognosis of prostate cancer. Thus, immunotherapy, targeted therapy and gene therapy could have reciprocal synergistic effects in prostate cancer in combination, resulting in a proposed synergistic model encompassing these three therapeutic modalities, presenting novel potential treatment strategies for prostate cancer.

The dual effects of propofol down-regulating PD-L1 expression and inhibiting autophagy to reduce cerebral ischemia reperfusion injury

Propofol, an anesthetic, has shown neuroprotective effects in animal and cellular models of cerebral ischemia-reperfusion (I/R) injury, likely by suppressing I/R-induced excessive autophagy. PD-L1 and immune escape are implicated in experimental stroke outcomes, but their mechanisms remain unclear. Here, we demonstrate that oxygen-glucose deprivation/reoxygenation (OGD/R) in astrocytes upregulates PD-L1 expression and autophagy, effects that are attenuated by propofol treatment via the NF-κB pathway. In vivo, propofol protects mice from I/R injury by downregulating PD-L1, inflammatory factors, and autophagy. Clinically, craniotomy patients receiving propofol exhibited higher CD3+ and CD4+ T lymphocyte percentages and lower PD-L1 and inflammatory factor levels. Our findings elucidate propofol's dual role in downregulating PD-L1 and inhibiting autophagy in cerebral I/R injury, suggesting its potential as a novel therapeutic strategy to mitigate inflammation and immune dysregulation.

The role of cGAS-STING in remodeling the tumor immune microenvironment induced by radiotherapy

The activation of the cGAS-STING pathway occurs when tumor cell DNA is damaged by ionizing radiation. Once triggered, this pathway reshapes the tumor immune microenvironment by promoting the maturation, activation, polarization, and immune-killing capacity of immune cells, as well as by inducing the release of interferons and the expression of immune-related genes. In addition, the gut microbiota and various mechanisms of programmed cell death interact with the cGAS-STING pathway, further influencing its function in remodeling the immune microenvironment after radiotherapy. Therefore, investigating the mechanisms of the cGAS-STING pathway in reshaping the tumor immune microenvironment post-radiotherapy can not only optimize the efficacy of combined radiotherapy and immunotherapy but also provide new research directions and potential targets for cancer treatment.

The RB protein: more than a sentry of cell cycle entry

Genomic instability is a hallmark of cancer. It fuels cancer progression and therapy resistance. As 'the guardian of the genome', the tumor suppressor protein p53 protects against genomic damage. Canonically, the retinoblastoma protein (RB) is 'the sentry of cell cycle entry', as it dictates whether a cell enters the cell cycle to divide. However, the RB pathway also controls myriad non-canonical cellular processes, including metabolism, stemness, angiogenesis, apoptosis, and immune surveillance. We discuss how frequent RB pathway inactivation and underlying mechanisms in cancers affect these processes. We focus on RB's - rather than p53's - 'guardian of the genome' functions in DNA replication, DNA repair, centrosome duplication, chromosome segregation, and chromatin organization. Finally, we review therapeutic strategies, challenges, and opportunities for targeting RB pathway alterations in cancer.

Recent Developments in Targeting the Cell Cycle in Melanoma

Melanoma is an aggressive cancer with rising incidence, particularly among older individuals. Despite advancements in targeted therapies for BRAF and MEK proteins and immunotherapies, many patients either fail to respond or develop resistance. For those progressing on immunotherapy, limited treatment options remain. The Cyclin D-CDK4/6-RB pathway is commonly dysregulated in melanoma, with up to 90% of cases showing alterations that activate it. Although targeting Cyclin-CDK complexes has shown promise in preclinical models, clinical responses have been suboptimal. This review explores the molecular mechanisms behind Cyclin-CDK dysregulation in melanoma and the challenges of targeting this pathway. It also discusses strategies to improve the efficacy of CDK4/6 inhibitors, including combination therapies to overcome resistance and enhance patient outcomes. Understanding these mechanisms can guide the development of more effective treatments for melanoma.

The transcription factor MEF2C restrains microglial overactivation by inhibiting kinase CDK2

Microglial intrinsic immune checkpoints are essential safeguards to maintain immune homeostasis by preventing microglial overactivation, a process that substantially influences neurological disorders such as autism spectrum disorder (ASD). MEF2C is a crucial immune checkpoint that regulates microglial activation, but the mechanism remains unclear. We found that MEF2C-deficient (MEF2C-/-) induced microglia-like cells (iMGLs) derived from human pluripotent stem cells (hPSCs) exhibited overactivation following lipopolysaccharide stimulation, mimicking patterns observed in various neuroinflammatory disorders. High-throughput screening identified BMS265246, a cyclin-dependent kinase 2 (CDK2) inhibitor, which suppressed overactivation of MEF2C-/- iMGLs and normalized their inflammatory responses. Mechanistically, MEF2C transcriptionally upregulated p21 to inhibit CDK2 activation-mediated retinoblastoma protein (RB) degradation, thereby preventing transcription factor nuclear factor κB (NFκB) nuclear translocation and consequent microglial overactivation. BMS265246 treatment substantially ameliorated microglial overactivation and ASD-like behaviors in Mef2c-deficient mice. Our findings identify the MEF2C-p21-CDK2-RB-NFκB axis as a critical pathway to maintain microglial homeostasis and highlight CDK2 as a potential therapeutic target for neuroinflammation.

Unleashing the power of peptides in prostate cancer immunotherapy: mechanism, facts and perspectives

Prostate cancer, the second most common cancer in men, often progresses to castration-resistant prostate cancer despite androgen deprivation therapy. Immunotherapy, revolutionary in cancer treatment, has limited efficacy in prostate cancer due to its "cold tumor" nature. Peptides, with unique advantages, offer new hope. This review explores how peptide-based tumor immunotherapy can transform prostate cancer from a "cold" to a "hot" state. It modulates the immunosuppressive tumor microenvironment by regulating non-immune cells (such as cancer-associated fibroblasts, endothelial cells, and adipose stromal cells), repolarizing tumor-associated macrophages, activating NK cells, and tuning cytokines. Additionally, peptides can induce immunogenic cell death (ICD) in prostate cancer cells through ferroptosis, pyroptosis, and autophagy modulation. The review also revisits existing prostate cancer immunotherapies, including immune checkpoint blockade, CAR T cell therapy, and dendritic cell vaccines, highlighting how peptides can enhance their effectiveness and safety. Finally, two peptide-based immunotherapy strategies in the development stage, peptide-integrated Proteolysis-Targeting Chimera therapy and peptide-involved epigenomic therapy, are introduced, showing great potential for future prostate cancer treatment.

CDK4/6 inhibitors upregulate cIAP1/2, and Smac mimetic LCL161 enhances their antitumor effects in cholangiocarcinoma cells

Cholangiocarcinoma (CCA) is a highly aggressive bile duct cancer with a poor prognosis and high mortality rates, primarily due to the lack of early diagnosis and effective treatments. We have shown that cyclin D and CDK4/6, key regulators of cell cycle progression, are highly expressed in CCA patients. Moreover, high levels of cyclin D, CDK4, and CDK6 are associated with shorter survival in CCA patients, suggesting that cyclin D and CDK4/6 might be potential targets for CCA therapy. However, we have demonstrated that CDK4/6 inhibitor palbociclib monotherapy is less effective in CCA cells. We have identified Cellular Inhibitor of Apoptosis Proteins 1 and 2 (cIAP1/2), NF-κB target genes that their expression is associated with shorter survival in CCA patients, as potential key regulators of the CDK4/6 inhibitor response. We showed that palbociclib, a CDK4/6 inhibitor, increases phosphorylated p65 and its nuclear translocation, resulting in cIAP1/2 upregulation in CCA cells. Therefore, we hypothesized that the combination of a cIAP1/2 antagonist and a CDK4/6 inhibitor might enhance the CDK4/6 inhibitor response. Interestingly, combined treatment with the Smac mimetic LCL161, a cIAP1/2 antagonist, and palbociclib synergistically inhibits cell proliferation and induces cell death in both 2D monolayer and 3D spheroid CCA cultures. We further showed that this combination treatment has less effect on non-tumor cholangiocytes and human peripheral blood mononuclear cells (PBMCs). Our findings demonstrate for the first time that the combined treatment of Smac mimetics and CDK4/6 inhibitors is a promising novel targeted therapy for CCA patients.

Zinc-copper bimetallic nanoplatforms trigger photothermal-amplified cuproptosis and cGAS-STING activation for enhancing triple-negative breast cancer immunotherapy

Triple-negative breast cancer (TNBC) is characterized by high rates of metastasis and recurrence, along with a low sensitivity to immunotherapy, resulting in a paucity of effective therapeutic strategies. Herein, we have developed polydopamine-coated zinc-copper bimetallic nanoplatforms (Cu-ZnO2@PDA nanoplatforms, abbreviated CZP NPs) that can efficiently induce photothermal amplified cuproptosis and cGAS-STING signaling pathway activation, thereby reversing the immunosuppressive tumor microenvironment of TNBC, upregulating PD-L1 expression, and boosting the efficacy of anti-programmed death-ligand 1 antibody (αPD-L1)-based immunotherapy. Within the acidic tumor microenvironment (TME), CZP NPs spontaneously release copper and zinc ions and hydrogen peroxide, generating highly oxidative hydroxyl radicals and downregulating iron-sulfur cluster proteins. These actions lead to the disruption of mitochondrial integrity, the release of mitochondrial DNA (mtDNA) and irreversible cuproptosis. The further synergy between mtDNA and zinc ions potentiates the activation of the cGAS-STING signaling pathway, triggering a robust antitumor immune response and sensitizing TNBC to αPD-L1 therapy. Additionally, using an 808 nm near-infrared laser for photothermal therapy significantly augments these effects, resulting in a cascade amplification of therapeutic efficacy against TNBC. The strategic combination of CZP NPs with αPD-L1 markedly bolsters antitumor immunity and suppresses tumor growth. Collectively, our findings present a promising synergistic strategy for TNBC treatment by linking cuproptosis, cGAS-STING activation, photothermal therapy, and immunotherapy.

RB functions as a key regulator of senescence and tumor suppression

The Retinoblastoma (RB) protein is crucial for regulating gene transcription and chromatin remodeling, impacting cell cycle progression, cellular senescence, and tumorigenesis. Cellular senescence, characterized by irreversible growth arrest and phenotypic alterations, serves as a vital barrier against tumor progression and age-related diseases. RB is crucial in mediating senescence and tumor suppression by modulating the RB-E2F pathway and cross talking with other key senescence effectors such as p53 and p16INK4a. The interplay between RB-mediated cell cycle arrest and cellular senescence offers critical insights into tumorigenesis and potential therapeutic strategies. Leveraging RB-mediated senescence presents promising opportunities for cancer therapy, including novel approaches in tumor immunotherapy designed to enhance treatment efficacy. This review highlights recent advancements in the RB signaling pathway, focusing on its roles in cellular senescence and tumor suppression, and discusses its potential to improve tumor management and clinical outcomes.

PAK2 as a therapeutic target in cancer: Mechanisms, challenges, and future perspectives

P21-activated kinases (PAKs) are crucial regulators within cellular signaling pathways and have been implicated in a range of human diseases, including cancer. Among the PAK family, PAK2 is widely expressed across various tissues and has emerged as a significant driver of cancer progression. However, systematic studies on PAK2 remain limited. This review provides a comprehensive overview of PAK2's role in cancer, focusing on its involvement in processes such as angiogenesis, metastasis, cell survival, metabolism, immune response, and drug resistance. We also explore its function in key cancer signaling pathways and the potential of small-molecule inhibitors targeting PAK2 for therapeutic purposes. Despite promising preclinical data, no PAK2 inhibitors have reached clinical practice, underscoring challenges related to their specificity and therapeutic application. This review highlights the biological significance of PAK2 in cancer and its interactions with critical signaling pathways, offering valuable insights for future research. We also discuss the major obstacles in developing PAK inhibitors and propose strategies to overcome these barriers, paving the way for their clinical translation.

Interactions between key genes and pathways in prostate cancer progression and therapy resistance

Prostate cancer is one of the most prevalent malignant tumors in men, particularly in regions with a high Human Development Index. While the long-term survival rate for localized prostate cancer is relatively high, the mortality rate remains significantly elevated once the disease progresses to advanced stages, even with various intensive treatment modalities. The primary obstacle to curing advanced prostate cancer is the absence of comprehensive treatment strategies that effectively target the highly heterogeneous tumors at both genetic and molecular levels. Prostate cancer development is a complex, multigenic, and multistep process that involves numerous gene mutations, alteration in gene expression, and changes in signaling pathways. Key genetic and pathway alterations include the amplification and/or mutation of the androgen receptor, the loss of Rb, PTEN, and p53, the activation of the WNT signaling pathway, and the amplification of the MYC oncogene. This review summarizes the mechanisms by which these genes influence the progression of prostate cancer and highlights the interactions between multiple genes and their relationship with prostate cancer. Additionally, we reviewed the current state of treatments targeting these genes and signaling pathways, providing a comprehensive overview of therapeutic approaches in the context of prostate cancer.

Prognostic assessment value of immune escape-related genes in patients with acute myeloid leukemia

This study explores the prognostic value of immune escape-related genes in acute myeloid leukemia (AML) patients. Using TARGET_AML and GSE37642 datasets, we identified CEP55, DNAJC13, and EMC2 as significant prognostic indicators, with high transcript abundance correlating with poor outcomes. Consensus clustering divided patients into two groups, with Cluster 1 showing worse prognosis. A prognostic signature based on these genes stratified patients into high- and low-risk groups, with the high-risk group experiencing worse outcomes. The risk score was an independent prognostic factor. Functional analysis revealed that high-risk genes could promote cell cycle progression. The selected genes were strongly associated with immune cells, particularly mast cells and CD8+ T cells. This study enriches the prognostic evaluation system for AML and suggests a new therapeutic direction.

Resistance mechanisms and therapeutic strategies of CDK4 and CDK6 kinase targeting in cancer

Cyclin-dependent kinases (CDKs) 4 and 6 (CDK4/6) are important regulators of the cell cycle. Selective CDK4/6 small-molecule inhibitors have shown clinical activity in hormonal receptor-positive (HR+) metastatic breast cancer, but their effectiveness remains limited in other cancer types. CDK4/6 degradation and improved selectivity across CDK paralogs are approaches that could expand the effectiveness of CDK4/6 targeting. Recent studies also suggest the use of CDK4/6-targeting agents in cancer immunotherapy. In this Review, we highlight recent advancements in the mechanistic understanding and development of pharmacological approaches targeting CDK4/6. Collectively, these developments pose new challenges and opportunities for rationally designing more effective treatments.

Pancreatic ductal adenocarcinoma cells reshape the immune microenvironment: Molecular mechanisms and therapeutic targets

Pancreatic ductal adenocarcinoma (PDAC) is a digestive system malignancy characterized by challenging early detection, limited treatment alternatives, and generally poor prognosis. Although there have been significant advancements in immunotherapy for hematological malignancies and various solid tumors in recent decades, with impressive outcomes in recent preclinical and clinical trials, the effectiveness of these therapies in treating PDAC continues to be modest. The unique immunological microenvironment of PDAC, especially the abnormal distribution, complex composition, and variable activation states of tumor-infiltrating immune cells, greatly restricts the effectiveness of immunotherapy. Undoubtedly, integrating data from both preclinical models and human studies helps accelerate the identification of reliable molecules and pathways responsive to targeted biological therapies and immunotherapies, thereby continuously optimizing therapeutic combinations. In this review, we delve deeply into how PDAC cells regulate the immune microenvironment through complex signaling networks, affecting the quantity and functional status of immune cells to promote immune escape and tumor progression. Furthermore, we explore the multi-modal immunotherapeutic strategies currently under development, emphasizing the transformation of the immunosuppressive environment into an anti-tumor milieu by targeting specific molecular and cellular pathways, providing insights for the development of novel treatment strategies.

Double-Faced Immunological Effects of CDK4/6 Inhibitors on Cancer Treatment: Challenges and Perspectives

Cyclin-dependent kinases (CDKs) are generally involved in the progression of cell cycle and cell division in normal cells, while abnormal activations of CDKs are deemed to be a driving force for accelerating cell proliferation and tumorigenesis. Therefore, CDKs have become ideal therapeutic targets for cancer treatment. The U.S FDA has approved three CDK4/6 inhibitors (CDK4/6is) for the treatment of patients with hormone receptor-positive (HR+) or human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer, and these drugs showed impressive results in clinics. Besides cell-cycle arrest, there is growing evidence that CDK4/6is exert paradoxical roles on cancer treatment by altering the immune system. Indeed, clinical data showed that CDK4/6is could change the immune system to exert antitumor effects, while these changes also caused tumor resistance to CDK4/6i. However, the molecular mechanism for the regulation of the immune system by CDK4/6is is unclear. In this review, we comprehensively discuss the paradoxical immunological effects of CDK4/6is in cancer treatment, elucidating their anticancer mechanisms through immunomodulatory activity and induction of acquired drug resistance by dysregulating the immune microenvironment. More importantly, we suggest a few strategies including combining CDK4/6is with immunotherapy to overcome drug resistance.

Integrative Multiomic Profiling of Triple-Negative Breast Cancer for Identifying Suitable Therapies

PURPOSE

Triple-negative breast cancer (TNBC) is a heterogeneous disease that carries the poorest prognosis of all breast cancers. Although novel TNBC therapies in development are frequently targeted toward tumors carrying a specific genomic, transcriptomic, or protein biomarker, it is poorly understood how these biomarkers are correlated.

EXPERIMENTAL DESIGN

To better understand the molecular features of TNBC and their correlation with one another, we performed multimodal profiling on a cohort of 95 TNBC. Our approach involved quantifying tumor-infiltrating lymphocytes through hematoxylin and eosin staining, assessing the abundance of retinoblastoma, androgen receptor, and PDL1 proteins through IHC, and carrying out transcriptomic profiling using the NanoString BC360 platform, targeted DNA sequencing on a subset of cases, as well as evaluating associations with overall survival.

RESULTS

Levels of RB1 mRNA and RB proteins are better correlated with markers of retinoblastoma functionality than RB1 mutational status. Luminal androgen receptor tumors clustered into two groups with transcriptomes that cluster with either basal or mesenchymal tumors. Tumors classified as PDL1-positive by the presence of immune or tumor cells showed similar biological characteristics. HER2-low TNBC showed no distinct biological phenotype when compared with HER2-zero. The majority of TNBC were classified as basal or HER2-enriched by PAM50, the latter showing significantly improved overall survival.

CONCLUSIONS

Our study contributes new insights into biomarker utility for identifying suitable TNBC therapies and the intercorrelations between genomic, transcriptomic, protein, and cellular biomarkers. Additionally, our rich data resource can be used by other researchers to explore the interplay between DNA, RNA, and protein biomarkers in TNBC.

Prostate cancer microenvironment: multidimensional regulation of immune cells, vascular system, stromal cells, and microbiota

BACKGROUND

Prostate cancer (PCa) is one of the most prevalent malignancies in males worldwide. Increasing research attention has focused on the PCa microenvironment, which plays a crucial role in tumor progression and therapy resistance. This review aims to provide a comprehensive overview of the key components of the PCa microenvironment, including immune cells, vascular systems, stromal cells, and microbiota, and explore their implications for diagnosis and treatment.

METHODS

Keywords such as "prostate cancer", "tumor microenvironment", "immune cells", "vascular system", "stromal cells", and "microbiota" were used for literature retrieval through online databases including PubMed and Web of Science. Studies related to the PCa microenvironment were selected, with a particular focus on those discussing the roles of immune cells, vascular systems, stromal cells, and microbiota in the development, progression, and treatment of PCa. The selection criteria prioritized peer-reviewed articles published in the last five years, aiming to summarize and analyze the latest research advancements and clinical relevance regarding the PCa microenvironment.

RESULTS

The PCa microenvironment is highly complex and dynamic, with immune cells contributing to immunosuppressive conditions, stromal cells promoting tumor growth, and microbiota potentially affecting androgen metabolism. Vascular systems support angiogenesis, which fosters tumor expansion. Understanding these components offers insight into the mechanisms driving PCa progression and opens avenues for novel therapeutic strategies targeting the tumor microenvironment.

CONCLUSIONS

A deeper understanding of the PCa microenvironment is crucial for advancing diagnostic techniques and developing precision therapies. This review highlights the potential of targeting the microenvironment to improve patient outcomes, emphasizing its significance in the broader context of PCa research and treatment innovation.

The SASP factor IL-6 sustains cell-autonomous senescent cells via a cGAS-STING-NFκB intracrine senescent noncanonical pathway

Senescent cells produce a Senescence-Associated Secretory Phenotype (SASP) that involves factors with diverse and sometimes contradictory activities. One key SASP factor, interleukin-6 (IL-6), has the potential to amplify cellular senescence in the SASP-producing cells in an autocrine action, while simultaneously inducing proliferation in the neighboring cells. The underlying mechanisms for the contrasting actions remain unclear. We found that the senescence action does not involve IL-6 secretion nor the interaction with the receptor expressed in the membrane but is amplified through an intracrine mechanism. IL-6 sustains intracrine senescence interacting with the intracellular IL-6 receptor located in anterograde traffic specialized structures, with cytosolic DNA, cGAS-STING, and NFκB activation. This pathway triggered by intracellular IL-6 significantly contributes to cell-autonomous induction of senescence and impacts in tumor growth control. Inactivation of IL-6 in somatotrophic senescent cells transforms them into strongly tumorigenic in NOD/SCID mice, while re-expression of IL-6 restores senescence control of tumor growth. The intracrine senescent IL-6 pathway is further evidenced in three human cellular models of therapy-induced senescence. The compartmentalization of the intracellular signaling, in contrast to the paracrine tumorigenic action, provides a pathway for IL-6 to sustain cell-autonomous senescent cells, driving the SASP, and opens new avenues for clinical consideration to senescence-based therapies.

Identification of CDK4/6 Inhibitors as Small Molecule NLRP3 Inflammasome Activators that Facilitate IL-1β Secretion and T Cell Adjuvanticity

Several FDA-approved adjuvants signal through the NLRP3 inflammasome and IL-1β release. Identifying small molecules that induce IL-1β release could allow targeted delivery and structure-function optimization, thereby improving safety and efficacy of next-generation adjuvants. In this work, we leverage our existing high throughput data set to identify small molecules that induce IL-1β release. We find that ribociclib induces IL-1β release when coadministered with a TLR4 agonist in an NLRP3- and caspase-dependent fashion. Ribociclib was formulated with a TLR4 agonist into liposomes, which were used as an adjuvant in an ovalbumin prophylactic vaccine model. The liposomes induced antigen-specific immunity in an IL-1 receptor-dependent fashion. Furthermore, the liposomes were coadministered with a tumor antigen and used in a therapeutic cancer vaccine, where they facilitated rejection of E.G7-OVA tumors. While further chemical optimization of the ribociclib scaffold is needed, this study provides proof-of-concept for its use as an IL-1 producing adjuvant in various immunotherapeutic contexts.

Programmed death receptor (PD-)1/PD-ligand (L)1 in urological cancers : the "all-around warrior" in immunotherapy

Programmed death receptor-1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1) are essential molecules that are key in modulating immune responses. PD-L1 is constitutively expressed on various immune cells, epithelial cells, and cancer cells, where it functions as a co-stimulatory molecule capable of impairing T-cell mediated immune responses. Upon binding to PD-1 on activated T-cells, the PD-1/PD-L1 interaction triggers signaling pathways that can induce T-cell apoptosis or anergy, thereby facilitating the immune escape of tumors. In urological cancers, including bladder cancer (BCa), renal cell carcinoma (RCC), and prostate cancer (PCa), the upregulation of PD-L1 has been demonstrated. It is linked to poor prognosis and enhanced tumor immune evasion. Recent studies have highlighted the significant role of the PD-1/PD-L1 axis in the immune escape mechanisms of urological cancers. The interaction between PD-L1 and PD-1 on T-cells further contributes to immunosuppression by inhibiting T-cell activation and proliferation. Clinical applications of PD-1/PD-L1 checkpoint inhibitors have shown promising efficacy in treating advanced urological cancers, significantly improving patient outcomes. However, resistance to these therapies, either intrinsic or acquired, remains a significant challenge. This review aims to provide a comprehensive overview of the role of the PD-1/PD-L1 signaling pathway in urological cancers. We summarize the regulatory mechanism underlying PD-1 and PD-L1 expression and activity, including genetic, epigenetic, post-transcriptional, and post-translational modifications. Additionally, we discuss current clinical research on PD-1/PD-L1 inhibitors, their therapeutic potential, and the challenges associated with resistance. Understanding these mechanisms is crucial for developing new strategies to overcome therapeutic limitations and enhance the efficacy of cancer immunotherapy.

NLRP4 renders pancreatic cancer resistant to olaparib through promotion of the DNA damage response and ROS-induced autophagy

Olaparib has been approved as a therapeutic option for metastatic pancreatic ductal adenocarcinoma patients with BRCA1/2 mutations. However, a significant majority of pancreatic cancer patients have inherent resistance or develop tolerance to olaparib. It is crucial to comprehend the molecular mechanism underlying olaparib resistance to facilitate the development of targeted therapies for pancreatic cancer. In this study, we conducted an analysis of the DepMap database to investigate gene expression variations associated with olaparib sensitivity. Our findings revealed that NLRP4 upregulation contributes to increased resistance to olaparib in pancreatic cancer cells, both in vitro and in vivo. RNA sequencing and Co-IP MS analysis revealed that NLRP4 is involved in the DNA damage response and autophagy pathway. Our findings confirmed that NLRP4 enhances the capacity for DNA repair and induces the production of significant levels of reactive oxygen species (ROS) and autophagy in response to treatment with olaparib. Specifically, NLRP4-generated mitochondrial ROS promote autophagy in pancreatic cancer cells upon exposure to olaparib. However, NLRP4-induced ROS do not affect DNA damage. The inhibition of mitochondrial ROS using MitoQ and autophagy using chloroquine (CQ) may render cells more susceptible to the effects of olaparib. Taken together, our findings highlight the significant roles played by NLRP4 in the processes of autophagy and DNA repair when pancreatic cancer cells are treated with olaparib, thereby suggesting the potential therapeutic utility of olaparib in pancreatic cancer patients with low NLRP4 expression.

CD58 defines regulatory macrophages within the tumor microenvironment

CD58 has been implicated in immune suppression and is associated with stemness in various types of cancer. Nonetheless, efficient biomarkers for assessing cancer patient response to immunotherapy are lacking. The present work focused on assessing the immune predictive significance of CD58 for patients with glioma. The expression of CD58 correlates with the clinicopathologic characteristics of patients with glioma, suggesting CD58high cells to signify glioma with tumorigenic potential. The CD58high cells displayed accelerated tumor formation compared to CD58low cells in vivo. Taken together, CD58 could potentially serve as a marker for glioma. CD58high glioma induces macrophage polarization through CXCL5 secretion, where M2 macrophages regulate PD-L1 expression within CD58high glioma via IL-6 production in vitro. Moreover, it was found that combination treatment with CD58 significantly increased the volume of tumors in the xenograft specimens. Evaluating CD58 expression represents a promising approach for identifying patients who can benefit from immunotherapy.

CDK4/6 Alters TBK1 Phosphorylation to Inhibit the STING Signaling Pathway in Prostate Cancer

The efficacy of immunotherapy in patients with prostate cancer is limited due to the "cold" tumor microenvironment and the paucity of neoantigens. The STING-TBK1-IRF3 signaling axis is involved in innate immunity and has been increasingly recognized as a candidate target for cancer immunotherapy. Here, we found that treatment with CDK4/6 inhibitors stimulates the STING pathway and enhances the antitumor effect of STING agonists in prostate cancer. Mechanistically, CDK4/6 phosphorylated TBK1 at S527 to inactivate the STING signaling pathway independent of RB1 in prostate cancer cells. CDK4/6-mediated phosphorylation of RB1 at S249/T252 also induced the interaction of RB1 with TBK1 to diminish the phosphorylation of TBK1 at S172, which suppressed STING pathway activation. Overall, this study showed that CDK4/6 suppresses the STING pathway through RB1-dependent and RB1-independent pathways, indicating that CDK4/6 inhibition could be a potential strategy to overcome immunosuppression in prostate cancer. Significance: Inhibiting CDK4/6 activates STING-TBK1-IRF3 signaling in prostate cancer by regulating TBK1 phosphorylation, suggesting that the combination of CDK4/6 inhibitors and STING agonists could be an effective approach to stimulate innate immunity.

miR-122-3p targets UBE2I to regulate the immunosuppression of liver cancer and the intervention of Liujunzi formula

ETHNOPHARMACOLOGICAL RELEVANCE

Liujunzi formula has been used to treat liver cancer in China for many years, but its underlying mechanism remains unclear. We previously found that decreased expression of miR-122-3p was associated with liver cancer. In this study, we aimed to explore the target of miR-122-3p and the effect of the Liujunzi formula on miR-122-3p and its downstream events in liver cancer.

MATERIAL AND METHODS

Bioinformatics pinpointed potential targets of miR-122-3p. The actual target was confirmed by miRNA mimic/inhibitor transfections and a dual-luciferase reporter assay. RNA-seq looked at downstream genes impacted by this target. Flow cytometry checked for changes in T cell apoptosis levels after exposing them to liver cancer cells. Gene expression was measured by RT-qPCR, western blotting, and immunofluorescence staining.

RESULTS

Cell experiments found the Liujunzi extract (LJZ) upregulated miR-122-3p and in a dose-dependent manner. Bioinformatics analysis found UBE2I was a potential target of miR-122-3p, which was validated through experiments using miRNA mimics/inhibitors and a dual-luciferase reporter assay. RNA-seq data implicated the NF-κB pathway as being downstream of the miR-122-3p/UBE2I axis, further confirmed by forcing overexpression of UBE2I. Bioinformatic evidence suggested a link between UBE2I and T cell infiltration in liver cancer. Given that the NF-κB pathway drives PD-L1 expression, which can inhibit T cell infiltration, we investigated whether PD-L1 is a downstream effector of miR-122-3p/UBE2I. This was corroborated through mining public databases, UBE2I overexpression studies, and tumor-T cell co-culture assays. In addition, we also confirmed that LJZ downregulates UBE2I and NF-κB/PD-L1 pathways through miR-122-3p. LJZ also suppressed SUMOylation in liver cancer cells and protected PD-1+ T cells from apoptosis induced by co-culture with tumor cells. Strikingly, a miR-122-3p inhibitor abrogated LJZ's effects on UBE2I and PD-L1, and UBE2I overexpression rescued the LJZ-mediated effects on NF-κB and PD-L1.

CONCLUSIONS

miR-122-3p targets UBE2I, thereby suppressing the NF-κB signaling cascade and downregulating PD-L1 expression, which potentiates anti-tumor immune responses. LJZ bolsters anti-tumor immunity by modulating the miR-122-3p/UBE2I/NF-κB/PD-L1 axis in liver cancer cells.

Immunopeptides: immunomodulatory strategies and prospects for ocular immunity applications

Immunopeptides have low toxicity, low immunogenicity and targeting, and broad application prospects in drug delivery and assembly, which are diverse in application strategies and drug combinations. Immunopeptides are particularly important for regulating ocular immune homeostasis, as the eye is an immune-privileged organ. Immunopeptides have advantages in adaptive immunity and innate immunity, treating eye immune-related diseases by regulating T cells, B cells, immune checkpoints, and cytokines. This article summarizes the application strategies of immunopeptides in innate immunity and adaptive immunity, including autoimmunity, infection, vaccine strategies, and tumors. Furthermore, it focuses on the mechanisms of immunopeptides in mediating ocular immunity (autoimmune diseases, inflammatory storms, and tumors). Moreover, it reviews immunopeptides' application strategies and the therapeutic potential of immunopeptides in the eye. We expect the immune peptide to get attention in treating eye diseases and to provide a direction for eye disease immune peptide research.

Targeting STAT3 potentiates CDK4/6 inhibitors therapy in head and neck squamous cell carcinoma

Anti-CDK4/6 therapy has been employed for the treatment for head and neck squamous cell carcinoma (HNSCC) with CDK4/6 hyperactivation, but the response rate is relatively low. In this study, we first showed that CDK4 and CDK6 was over-expressed and conferred poor prognosis in HNSCC. Moreover, in RB-positive HNSCC, STAT3 signaling was activated induced by CDK4/6 inhibition and STAT3 promotes RB deficiency by upregulation of MYC. Thirdly, the combination of Stattic and CDK4/6 inhibitor results in striking anti-tumor effect in vitro and in Cal27 derived animal models. Additionally, phospho-STAT3 level negatively correlates with RB expression and predicts poor prognosis in patients with HNSCC. Taken together, our findings suggest an unrecognized function of STAT3 confers to CDK4/6 inhibitors resistance and presenting a promising combination strategy for patients with HNSCC.

A CD36-dependent non-canonical lipid metabolism program promotes immune escape and resistance to hypomethylating agent therapy in AML

Environmental lipids are essential for fueling tumor energetics, but whether these exogenous lipids transported into cancer cells facilitate immune escape remains unclear. Here, we find that CD36, a transporter for exogenous lipids, promotes acute myeloid leukemia (AML) immune evasion. We show that, separately from its established role in lipid oxidation, CD36 on AML cells senses oxidized low-density lipoprotein (OxLDL) to prime the TLR4-LYN-MYD88-nuclear factor κB (NF-κB) pathway, and exogenous palmitate transfer via CD36 further potentiates this innate immune pathway by supporting ZDHHC6-mediated MYD88 palmitoylation. Subsequently, NF-κB drives the expression of immunosuppressive genes that inhibit anti-tumor T cell responses. Notably, high-fat-diet or hypomethylating agent decitabine treatment boosts the immunosuppressive potential of AML cells by hijacking CD36-dependent innate immune signaling, leading to a dampened therapeutic effect. This work is of translational interest because lipid restriction by US Food and Drug Administration (FDA)-approved lipid-lowering statin drugs improves the efficacy of decitabine therapy by weakening leukemic CD36-mediated immunosuppression.

Immune Microenvironment in Childhood Cancers: Characteristics and Therapeutic Challenges

The tumor immune microenvironment is pivotal in cancer initiation, advancement, and regulation. Its molecular and cellular composition is critical throughout the disease, as it can influence the balance between suppressive and cytotoxic immune responses within the tumor's vicinity. Studies on the tumor immune microenvironment have enriched our understanding of the intricate interplay between tumors and their immunological surroundings in various human cancers. These studies illuminate the role of significant components of the immune microenvironment, which have not been extensively explored in pediatric tumors before and may influence the responsiveness or resistance to therapeutic agents. Our deepening understanding of the pediatric tumor immune microenvironment is helping to overcome challenges related to the effectiveness of existing therapeutic strategies, including immunotherapies. Although in the early stages, targeted therapies that modulate the tumor immune microenvironment of pediatric solid tumors hold promise for improved outcomes. Focusing on various aspects of tumor immune biology in pediatric patients presents a therapeutic opportunity that could improve treatment outcomes. This review offers a comprehensive examination of recent literature concerning profiling the immune microenvironment in various pediatric tumors. It seeks to condense research findings on characterizing the immune microenvironment in pediatric tumors and its impact on tumor development, metastasis, and response to therapeutic modalities. It covers the immune microenvironment's role in tumor development, interactions with tumor cells, and its impact on the tumor's response to immunotherapy. The review also discusses challenges targeting the immune microenvironment for pediatric cancer therapies.

Induced dual-target rebalance simultaneously enhances efficient therapeutical efficacy in tumors

Multiple gene abnormalities are major drivers of tumorigenesis. NF-κB p65 overactivation and cGAS silencing are important triggers and genetic defects that accelerate tumorigenesis. However, the simultaneous correction of NF-κB p65 and cGAS abnormalities remains to be further explored. Here, we propose a novel Induced Dual-Target Rebalance (IDTR) strategy for simultaneously correcting defects in cGAS and NF-κB p65. By using our IDTR approach, we showed for the first time that oncolytic adenovirus H101 could reactivate silenced cGAS, while silencing GAU1 long noncoding RNA (lncRNA) inhibited NF-κB p65 overactivation, resulting in efficient in vitro and in vivo antitumor efficacy in colorectal tumors. Intriguingly, we further demonstrated that oncolytic adenoviruses reactivated cGAS by promoting H3K4 trimethylation of the cGAS promoter. In addition, silencing GAU1 using antisense oligonucleotides significantly reduced H3K27 acetylation at the NF-κB p65 promoter and inhibited NF-κB p65 transcription. Our study revealed an aberrant therapeutic mechanism underlying two tumor defects, cGAS and NF-κB p65, and provided an alternative IDTR approach based on oncolytic adenovirus and antisense oligonucleotides for efficient therapeutic efficacy in tumors.

Retinoblastoma-associated protein is important for TRIM24-mediated activation of the mTOR signaling pathway through DUSP2 action in prostate cancer

RB transcriptional corepressor 1 (RB) deletion is the most important genomic factor associated with the prognosis of castration-resistant prostate cancer (CRPC) patients receiving androgen receptor (AR) signaling inhibitor therapy. Loss of RB could support prostate cancer cell growth in a hormone-independent manner, but the underlying mechanism by which RB regulates tumor progression extends far beyond the cell cycle pathway. A previous study indicated that RB inactivates AKT signaling but has no effect on mTOR signaling in cancer cells. Here, we found that the S249/T252 site in RB is key to regulating the transcriptional activity of the tumor-promoting factor TRIM24 in CRPC, as identified through FXXXV mapping. The RB/TRIM24 complex functions through DUSP2, which serves as an intermediate bridge, to activate the mTOR pathway and promote prostate cancer progression. Accordingly, we designed RB-linker-proteolysis-targeting chimera (PROTAC) molecules, which decreased TRIM24 protein levels and inactivated the mTOR signaling pathway, thereby inhibiting prostate cancer. Therefore, this study not only elucidates the novel function of RB but also provides a theoretical basis for the development of new drugs for treating prostate cancer.

The gut microbiome-prostate cancer crosstalk is modulated by dietary polyunsaturated long-chain fatty acids

The gut microbiota modulates response to hormonal treatments in prostate cancer (PCa) patients, but whether it influences PCa progression remains unknown. Here, we show a reduction in fecal microbiota alpha-diversity correlating with increase tumour burden in two distinct groups of hormonotherapy naïve PCa patients and three murine PCa models. Fecal microbiota transplantation (FMT) from patients with high PCa volume is sufficient to stimulate the growth of mouse PCa revealing the existence of a gut microbiome-cancer crosstalk. Analysis of gut microbial-related pathways in mice with aggressive PCa identifies three enzymes responsible for the metabolism of long-chain fatty acids (LCFA). Supplementation with LCFA omega-3 MAG-EPA is sufficient to reduce PCa growth in mice and cancer up-grading in pre-prostatectomy PCa patients correlating with a reduction of gut Ruminococcaceae in both and fecal butyrate levels in PCa patients. This suggests that the beneficial effect of omega-3 rich diet is mediated in part by modulating the crosstalk between gut microbes and their metabolites in men with PCa.

Therapeutic Strategies for RB1-Deficient Cancers: Intersecting Gene Regulation and Targeted Therapy

The retinoblastoma (RB) transcriptional corepressor 1 (RB1) is a critical tumor suppressor gene, governing diverse cellular processes implicated in cancer biology. Dysregulation or deletion in RB1 contributes to the development and progression of various cancers, making it a prime target for therapeutic intervention. RB1's canonical function in cell cycle control and DNA repair mechanisms underscores its significance in restraining aberrant cell growth and maintaining genomic stability. Understanding the complex interplay between RB1 and cellular pathways is beneficial to fully elucidate its tumor-suppressive role across different cancer types and for therapeutic development. As a result, investigating vulnerabilities arising from RB1 deletion-associated mechanisms offers promising avenues for targeted therapy. Recently, several findings highlighted multiple methods as a promising strategy for combating tumor growth driven by RB1 loss, offering potential clinical benefits in various cancer types. This review summarizes the multifaceted role of RB1 in cancer biology and its implications for targeted therapy.

Effect of CDK4/6 Inhibitors on Tumor Immune Microenvironment

Cancer is an abnormal proliferation of cells that is stimulated by cyclin-dependent kinases (CDKs) and defective cell cycle regulation. The essential agent that drive the cell cycle, CDK4/6, would be activated by proliferative signals. Activated CDK4/6 results in the phosphorylation of the neuroblastoma protein (RB) and the release of the transcription factor E2F, which promotes the cell cycle progression. CDK4/6 inhibitor (CDK4/6i) has been currently a research focus, which inhibits the CDK4/6-RB-E2F axis, thereby reducing the cell cycle transition from G1 to S phase and mediating the cell cycle arrest. This action helps achieve an anti-tumor effect. Recent research has demonstrated that CDK4/6i, in addition to contributing to cell cycle arrest, is also essential for the interaction between the tumor cells and the host immune system, i.e., activating the immune system, strengthening the tumor antigen presentation, and reducing the number of regulatory T cells (Treg). Additionally, CDK4/6i would elevate the level of PD-L1, an immunosuppressive factor, in tumor cells, and CDK4/6i in combination with anti-PD-L1 therapy would more effectively reduce the tumor growth. Our results showed that CDK4/6i caused autophagy and senescence in tumor cells. Herein, the impact of CDK4/6i on the immune microenvironment of malignant tumors was mainly focused, as well as their interaction with immune checkpoint inhibitors in affecting anti-tumor immunity.

Patterns in the tapestry of chromatin-bound RB

The retinoblastoma protein (RB)-mediated regulation of E2F is a component of a highly conserved cell cycle machine. However, RB's tumor suppressor activity, like RB's requirement in animal development, is tissue-specific, context-specific, and sometimes appears uncoupled from cell proliferation. Detailed new information about RB's genomic distribution provides a new perspective on the complexity of RB function, suggesting that some of its functional specificity results from context-specific RB association with chromatin. Here we summarize recent evidence showing that RB targets different types of chromatin regulatory elements at different cell cycle stages. RB controls traditional RB/E2F targets prior to S-phase, but, when cells proliferate, RB redistributes to cell type-specific chromatin loci. We discuss the broad implications of the new data for RB research.

Recent advances and mechanisms of action of PD-L1 degraders as potential therapeutic agents

PD-L1 is an important immune checkpoint protein that can bind to T cells' PD-1 receptor, thereby promoting immune escape from tumors. In recent years, many researchers have developed strategies to degrade PD-L1 to improve the effect of immunotherapy. The study of degrading PD-L1 provides new opportunities for immunotherapy. Here, we mainly summarize and review the current active molecules and mechanisms that mediate the degradation of immature and mature PD-L1 during the post-translational modification stages, involving PD-L1 phosphorylation, glycosylation, palmitoylation, ubiquitination, and the autophagy-lysosomal process. This review expects that by degrading PD-L1 protein, we will not only gain a better understanding of oncogenic mechanisms involving tumor PD-L1 protein but also provide a new way to improve immunotherapy.

Recent progress in retinoblastoma: Pathogenesis, presentation, diagnosis and management

Retinoblastoma, the primary ocular malignancy in pediatric patients, poses a substantial threat to mortality without prompt and effective management. The prognosis for survival and preservation of visual acuity hinges upon the disease severity at the time of initial diagnosis. Notably, retinoblastoma has played a crucial role in unraveling the genetic foundations of oncogenesis. The process of tumorigenesis commonly begins with the occurrence of biallelic mutation in the RB1 tumor suppressor gene, which is then followed by a cascade of genetic and epigenetic alterations that correspond to the clinical stage and pathological features of the tumor. The RB1 gene, recognized as a tumor suppressor, encodes the retinoblastoma protein, which plays a vital role in governing cellular replication through interactions with E2F transcription factors and chromatin remodeling proteins. The diagnosis and treatment of retinoblastoma necessitate consideration of numerous factors, including disease staging, germline mutation status, family psychosocial factors, and the resources available within the institution. This review has systematically compiled and categorized the latest developments in the diagnosis and treatment of retinoblastoma which enhanced the quality of care for this pediatric malignancy.

Protein arginine methyltransferases (PRMTs): Orchestrators of cancer pathogenesis, immunotherapy dynamics, and drug resistance

Protein Arginine Methyltransferases (PRMTs) are a family of enzymes regulating protein arginine methylation, which is a post-translational modification crucial for various cellular processes. Recent studies have highlighted the mechanistic role of PRMTs in cancer pathogenesis, immunotherapy, and drug resistance. PRMTs are involved in diverse oncogenic processes, including cell proliferation, apoptosis, and metastasis. They exert their effects by methylation of histones, transcription factors, and other regulatory proteins, resulting in altered gene expression patterns. PRMT-mediated histone methylation can lead to aberrant chromatin remodeling and epigenetic changes that drive oncogenesis. Additionally, PRMTs can directly interact with key signaling pathways involved in cancer progression, such as the PI3K/Akt and MAPK pathways, thereby modulating cell survival and proliferation. In the context of cancer immunotherapy, PRMTs have emerged as critical regulators of immune responses. They modulate immune checkpoint molecules, including programmed cell death protein 1 (PD-1), through arginine methylation. Drug resistance is a significant challenge in cancer treatment, and PRMTs have been implicated in this phenomenon. PRMTs can contribute to drug resistance through multiple mechanisms, including the epigenetic regulation of drug efflux pumps, altered DNA damage repair, and modulation of cell survival pathways. In conclusion, PRMTs play critical roles in cancer pathogenesis, immunotherapy, and drug resistance. In this overview, we have endeavored to illuminate the mechanistic intricacies of PRMT-mediated processes. Shedding light on these aspects will offer valuable insights into the fundamental biology of cancer and establish PRMTs as promising therapeutic targets.

MYC induces CDK4/6 inhibitors resistance by promoting pRB1 degradation

CDK4/6 inhibitors (CDK4/6i) show anticancer activity in certain human malignancies, such as breast cancer. However, their application to other tumor types and intrinsic resistance mechanisms are still unclear. Here, we demonstrate that MYC amplification confers resistance to CDK4/6i in bladder, prostate and breast cancer cells. Mechanistically, MYC binds to the promoter of the E3 ubiquitin ligase KLHL42 and enhances its transcription, leading to RB1 deficiency by inducing both phosphorylated and total pRB1 ubiquitination and degradation. We identify a compound that degrades MYC, A80.2HCl, which induces MYC degradation at nanomolar concentrations, restores pRB1 protein levels and re-establish sensitivity of MYC high-expressing cancer cells to CDK4/6i. The combination of CDK4/6i and A80.2HCl result in marked regression in tumor growth in vivo. Altogether, these results reveal the molecular mechanisms underlying MYC-induced resistance to CDK4/6i and suggest the utilization of the MYC degrading molecule A80.2HCl to potentiate the therapeutic efficacy of CDK4/6i.

Targeting the NF-κB pathway as a potential regulator of immune checkpoints in cancer immunotherapy

Advances in cancer immunotherapy over the last decade have led to the development of several agents that affect immune checkpoints. Inhibitory receptors expressed on T cells that negatively regulate the immune response include cytotoxic T‑lymphocyte antigen 4 (CTLA4) and programmed cell death protein 1 (PD1), which have been studied more than similar receptors. Inhibition of these proteins and other immune checkpoints can stimulate the immune system to attack cancer cells, and prevent the tumor from escaping the immune response. However, the administration of anti-PD1 and anti-CTLA4 antibodies has been associated with adverse inflammatory responses similar to autoimmune diseases. The current review discussed the role of the NF-κB pathway as a tumor promoter, and how it can govern inflammatory responses and affect various immune checkpoints. More precise knowledge about the communication between immune checkpoints and NF-κB pathways could increase the effectiveness of immunotherapy and reduce the adverse effects of checkpoint inhibitor therapy.

IGFBP3 induces PD-L1 expression to promote glioblastoma immune evasion

BACKGROUND

Glioblastoma (GBM) characterized by immune escape is the most malignant primary brain tumors, which has strong immunosuppressive effect. Programmed death ligand-1 (PD-L1) is a recognized immunosuppressive member on the surface of tumor cells, and plays a crucial role in immune evasion of tumors. Actually, little is known about the regulation of PD-L1 expression in GBM. Insulin-like growth factor binding protein 3 (IGFBP3) is upregulated in GBM and is related to poor patient prognosis. However, it remains unclear whether IGFBP3 plays a role in the regulation of PD-L1 expression in GBM.

METHODS

The role of IGFBP3 in the glioma immune microenvironment was investigated using the CIBERSORT algorithm. The correlation between IGFBP3 and PD-L1 expression was analyzed using TCGA and CGGA databases. QRT-PCR, immunoblotting and RNA-seq were used to examine the regulatory effect of IGFBP3 on PD-L1 expression. Co-culture assay, cell counting kit (CCK-8), qRT-PCR, ELISA and flow cytometry were performed to explore the function of IGFBP3 in inducing immunosuppression. The biological role of IGFBP3 was verified using immunohistochemical, immunofluorescence and mice orthotopic tumor model.

RESULTS

In this study, we analyzed immune cells infiltration in gliomas and found that IGFBP3 may be associated with an immunosuppressive microenvironment. Then, by analyzing TCGA and CGGA databases, our results showed that IGFBP3 and PD-L1 expression were positively correlated in GBM patients, but not in LGG patients. In vitro experiments conducted on different GBM cell lines revealed that the overexpression of IGFBP3 led to an increase in PD-L1 expression, which was reversible upon knockdown IGFBP3. Mechanistically, IGFBP3 activated the JAK2/STAT3 signaling pathway, leading to an increase in PD-L1 expression. Additionally, co-culture experiments results showed IGFBP3 overexpression induced upregulation of PD-L1 expression promoted apoptosis in Jurkat cells, and this effect was blocked by IGFBP3 antibody and PDL-1 inhibitors. Importantly, in vivo experiments targeting IGFBP3 suppressed tumor growth and significantly prolonged the survival of mice.

CONCLUSIONS

This research demonstrated IGFBP3 is a novel regulator for PD-L1 expression in GBM, and identified a new mechanism by which IGFBP3 regulates immune evasion through PD-L1, suggesting that IGFBP3 may be a potential novel target for GBM therapy.

CDK4/6 inhibitors in lung cancer: current practice and future directions

Lung cancer is the leading cause of cancer-related deaths worldwide, and ∼85% of lung cancers are classified as nonsmall cell lung cancer (NSCLC). These malignancies can proliferate indefinitely, in part due to dysregulation of the cell cycle and the resulting abnormal cell growth. The specific activation of cyclin-dependent kinases 4 and 6 (CDK4/6) is closely linked to tumour proliferation. Approximately 80% of human tumours exhibit abnormalities in the cyclin D-CDK4/6-INK4-RB pathway. Specifically, CDK4/6 inhibitors either as monotherapy or combination therapy have been investigated in pre-clinical and clinical studies for the treatment of NSCLC, and promising results have been achieved. This review article focuses on research regarding the use of CDK4/6 inhibitors in NSCLC, including the characteristics and mechanisms of action of approved drugs and progress of pre-clinical and clinical research.

Beyond cell cycle regulation: The pleiotropic function of CDK4 in cancer

CDK4, along with its regulatory subunit, cyclin D, drives the transition from G1 to S phase, during which DNA replication and metabolic activation occur. In this canonical pathway, CDK4 is essentially a transcriptional regulator that acts through phosphorylation of retinoblastoma protein (RB) and subsequent activation of the transcription factor E2F, ultimately triggering the expression of genes involved in DNA synthesis and cell cycle progression to S phase. In this review, we focus on the newly reported functions of CDK4, which go beyond direct regulation of the cell cycle. In particular, we describe the extranuclear roles of CDK4, including its roles in the regulation of metabolism, cell fate, cell dynamics and the tumor microenvironment. We describe direct phosphorylation targets of CDK4 and decipher how CDK4 influences these physiological processes in the context of cancer.

IL-18 serves as a main effector of CAF-derived METTL3 against immunosuppression of NSCLC via driving NF-κB pathway

Background: N6-methyladenosine (m6A) is the most abundant modification in eukaryotic mRNA. However, its role in non-small cell lung cancer (NSCLC) has not been completely elucidated.Objective: To explore whether methyltransferase like 3 (METTL3) in cancer associated fibroblasts (CAFs) affects the secretion of IL-18, which drives NSCLC cells to regulate PD-L1-mediated immunosuppression via the nuclear factor kappa B (NF-κB) pathway.Methods: Histopathological features of NSCLC tissues were identified by H&E and IHC staining. The levels of m6A writers (METTL3), IL-18 and NF-κB pathway related genes were assessed. The quantity of CD8+ T cells was evaluated by flow cytometry (FCM). The direct binding relationship between METTL3 and IL-18 mRNA was detected by RIP assay and RNA pulldown and confirmed by dual - luciferase reporter assay. The level of RNA m6A was detected by RNA m6A dot blot and meRIP assays. A heterotopic implantation model of NSCLC was established in NOD-SCID mice for further explore the effect of CAF derived METTL3 on immunosuppression of NSCLC in vivo.Results: Our results illustrated that METTL3 was down-regulated in CAFs, and CAF derived METTL3 alleviated PD-L1-mediated immunosuppression of NSCLC through IL-18. Subsequently, we found that IL-18 was main effector of CAF-derived METTL3 against immunosuppression of NSCLC, and IL-18 accelerated immunosuppression of NSCLC by driving NF-κB pathway. In vivo, METTL3 knockdown-derived CAFs accelerated immunosuppression of NSCLC.Conclusion: IL-18 served as a main effector of CAF-derived METTL3 against immunosuppression of NSCLC via driving NF-κB pathway.

Targeting CBX3 with a Dual BET/PLK1 Inhibitor Enhances the Antitumor Efficacy of CDK4/6 Inhibitors in Prostate Cancer

The development of castration-resistant prostate cancer (CRPC) is a significant factor that reduces life expectancy among patients with prostate cancer. Previously, it is reported that CDK4/6 inhibitors can overcome the resistance of CRPC to BET inhibitors by destabilizing BRD4, suggesting that the combination of CDK4/6 inhibitors and BET inhibitors is a promising approach for treating CRPC. In this study, candidates that affect the combined antitumor effect of CDK4/6 inhibitors and BET inhibitors on CRPC is aimed to examine. The data demonstrates that CBX3 is abnormally upregulated in CDK4/6 inhibitors-resistant cells. CBX3 is almost positively correlated with the cell cycle in multiple malignancies and is downregulated by BET inhibitors. Mechanistically, it is showed that CBX3 is transcriptionally upregulated by BRD4 in CRPC cells. Moreover, it is demonstrated that CBX3 modulated the sensitivity of CRPC to CDK4/6 inhibitors by binding with RB1 to release E2F1. Furthermore, it is revealed that PLK1 phosphorylated CBX3 to enhance the interaction between RB1 and CBX3, and desensitize CRPC cells to CDK4/6 inhibitors. Given that BRD4 regulates CBX3 expression and PLK1 affects the binding between RB1 and CBX3, it is proposed that a dual BRD4/PLK1 inhibitor can increase the sensitivity of CRPC cells to CDK4/6 inhibitors partially through CBX3.

Characterization of tumor microenvironment infiltration and therapeutic responses of cell cycle-related genes' signature in breast cancer

BACKGROUND

It is unknown how the cell cycle plays a role in breast cancer (BC). This study aimed to establish a clinically applicable predictive model to predict the therapeutic responses and overall survival in BC patients.

MATERIALS AND METHODS

Cell cycle-related genes (CCGs) were identified within the Cancer Genome Atlas cohort (n is equal to 1001) and the Gene Expression Omnibus cohort (n is equal to 3265). An analysis of univariate and multivariate Cox was then conducted to develop a nomogram based on CCGs. After validating the nomogram, risk cohort stratification was established and the predictive value was examined. Finally, immune cell infiltration and therapeutic responses were analysed.

RESULTS

Based on 15 CCGs, 4 prognostic predictors were identified and entered into the nomogram. According to the curves of calibration, the estimated and observed value of the nomogram is in optimal agreement. Subsequently, stratification into two risk cohorts showed that the predictive value, immune cell infiltration and overall survival were better among patients with low risk. Immune checkpoint expression in patients with BC at higher risk was downregulated. Furthermore, the results of the study revealed that doxorubicin, paclitaxel, docetaxel, cisplatin and vinorelbine all had higher IC50 values in patients with high-risk BC.

CONCLUSION

The nomogram based on CCG could assess tumour immune micro-environment regulation and therapeutic responses of immunotherapy in BC. Moreover, it may provide novel information on the control of immune micro-environment infiltration in BC and aid in the development of targeted immunotherapy.

The Evolving Pathways of the Efficacy of and Resistance to CDK4/6 Inhibitors in Breast Cancer

The approval of cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) in combination with endocrine therapy (ET) has remarkably improved the survival outcomes of patients with advanced hormone receptor-positive (HR+) breast cancer (BC), becoming the new standard of care treatment in these patients. Despite the efficacy of this therapeutic combination, intrinsic and acquired resistance inevitably occurs and represents a major clinical challenge. Several mechanisms associated with resistance to CDK4/6i have been identified, including both cell cycle-related and cell cycle-nonspecific mechanisms. This review discusses new insights underlying the mechanisms of action of CDK4/6i, which are more far-reaching than initially thought, and the currently available evidence of the mechanisms of resistance to CDK4/6i in BC. Finally, it highlights possible treatment strategies to improve CDK4/6i efficacy, summarizing the most relevant clinical data on novel combination therapies involving CDK4/6i.

Critical Role of Novel O-GlcNAcylation of S550 and S551 on the p65 Subunit of NF-κB in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a mere 5-year survival of ~10%. This highlights the urgent need for innovative treatment options for PDAC patients. The nuclear factor κB (NF-κB) is a crucial transcription factor that is constitutively activated in PDAC. It mediates the transcription of oncogenic and inflammatory genes that facilitate multiple PDAC phenotypes. Thus, a better understanding of the mechanistic underpinnings of NF-κB activation holds great promise for PDAC diagnosis and effective therapeutics. Here, we report a novel finding that the p65 subunit of NF-κB is O-GlcNAcylated at serine 550 and 551 upon NF-κB activation. Importantly, the overexpression of either serine-to-alanine (S-A) single mutant (S550A or S551A) or double mutant (S550A/S551A) of p65 in PDAC cells impaired NF-κB nuclear translocation, p65 phosphorylation, and transcriptional activity, independent of IκBα degradation. Moreover, the p65 mutants downregulate a category of NF-κB-target genes, which play a role in perpetuating major cancer hallmarks. We further show that overexpression of the p65 mutants inhibited cellular proliferation, migration, and anchorage-independent growth of PDAC cells compared to WT-p65. Collectively, we discovered novel serine sites of p65 O-GlcNAcylation that drive NF-κB activation and PDAC phenotypes, thus opening new avenues by inhibiting the NF-κB O-GlcNAcylation enzyme, O-GlcNAc transferase (OGT), for PDAC treatment in the future.

The NEDD8-activating enzyme E1 UBA3 orchestrates the immunosuppressive microenvironment in lung adenocarcinoma via the NF-кB pathway

Immunosuppressive cells play important roles in generating an immunosuppressive tumor microenvironment and facilitating tumor immune escape. However, the molecular mechanisms underlying their immunosuppressive effects remain unclear. UBA3, the sole catalytic subunit of the neural precursor cell expressed developmentally down-regulated protein 8 (NEDD8)-activating enzyme E1, is highly expressed in various human malignancies, along with an activated neddylation pathway. In this study, we investigated the relationships between the UBA3-dependent neddylation pathway and the infiltration of several immunosuppressive cell populations in lung adenocarcinoma (LUAD). We explored the regulatory mechanisms of UBA3 in LUAD cells by using mRNA sequencing and functional enrichment analyses. Correlations between neddylation and immune infiltrates were assessed by Western blotting, real-time PCR, and analyses of public databases. We found elevated levels of UBA3 expression in LUAD tissues compared to adjacent normal tissues. Blocking UBA3 and the neddylation pathway promoted the accumulation of the phosphorylated nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (p-IκBα), inhibiting the gene expression of tumor cell-derived cytokines such as C-C motif chemokine ligand (CCL) 2, C-X-C motif ligand (CXCL)1, CXCL2, colony-stimulating factor (CSF) 1, CSF2 interleukin (IL)-6, and IL-1B. Moreover, the overexpression of UBA3 in LUAD cells was associated with the secretion of these cytokines, and the recruitment and infiltration of immunosuppressive cells including tumor-associated macrophages (TAMs), plasmacytoid dendritic cells (pDCs), Th2 cells and T-regulatory cells (Tregs). This could facilitate the tumor immune escape and malignant progression of LUAD. Our findings provide new insights into the role of UBA3 in establishing an immunosuppressive tumor microenvironment by modulating nuclear factor kappa B (NF-кB) signaling and the neddylation pathway.