Inhibition Lysosomal Degradation of Clusterin by Protein Kinase D3 Promotes Triple-Negative Breast Cancer Tumor Growth

Effect of PRKD3 on cell cycle in gastric cancer progression and downstream regulatory networks

Protein kinase D3 (PRKD3), belonging to the protein kinase D family, significantly influences tumor development and progression. The role of PRKD3 in advancing gastric cancer (GC) and its effects on the cell cycle are not well understood, necessitating detailed investigation. Assessment of PRKD3 expression in both malignant and normal gastric tissues was performed using bioinformatics databases. The influence of PRKD3 on GC's malignant characteristics was evaluated through in vitro experiments utilizing cell line models of GC. Additionally, proteomic analyses were conducted to investigate the potential mechanisms of PRKD3 in GC progression. PRKD3 was notably overexpressed in GC tissues, correlating with adverse outcomes for patients. PRKD3 knockdown impaired GC cell malignancy, manifesting as a 2.12-fold decline in proliferation(p < 0.01), 2.64-fold suppression of migration(p < 0.01), 2.16-fold inhibition of invasion(p < 0.01), and G2/M phase arrest. Proteomic and Western blot analyses had revealed a substantial enrichment in differentially expressed proteins (DEPs) associated with tumor-related signaling pathways, including FoxO and p53, which was paralleled by significant alterations in the levels of key cell cycle proteins such as CDK1, CyclinB1, CHK1 and PLK1, with a 6.8-fold elevation in CHK1 levels(p < 0.05). The overexpression of PRKD3 was intricately linked with the aggressive behaviors of GC. Targeting PRKD3 activity offers potential for effective treatments of GC.

Engineered CAR-NK Cells with Tolerance to H2O2 and Hypoxia Can Suppress Postoperative Relapse of Triple-Negative Breast Cancers

Surgical resection is a primary treatment option for patients with triple-negative breast cancer (TNBC), but it is associated with a high rate of postoperative local and metastatic relapse. Although chimeric antigen receptor-engineered NK (CAR-NK) cell therapy can specifically recognize and eradicate tumor cells, its therapeutic potency toward TNBCs is markedly suppressed by the hostile tumor microenvironment, which restricts the infiltration, survival, and effector functions of CAR-NK cells inside tumor masses. In this study, HER1-overexpressing TNBC-targeted CAR-NK (HER1-CAR-NK) cells were genetically engineered with catalase to endow them with tolerance toward the high levels of oxidative stress and hypoxia inside TNBC tumors through the catalytic decomposition of hydrogen peroxide, which is a principle reactive oxygen species inside tumors, into O2. We refer to these cells as HER1-CAR-CAT-NK cells. Upon intratumoral fixation with an injectable alginate hydrogel, HER1-CAR-CAT-NK cells enabled sustained tumor hypoxia attenuation and exhibited markedly enhanced persistence and effector functions inside TNBC tumors. As a result, locoregional HER1-CAR-CAT-NK cell therapy not only inhibited the growth of local primary residual tumors but also elicited systemic antitumor activity to suppress the growth of distant tumors. This study highlights that genetic engineering of HER1-CAR-NK cells with catalase is a promising strategy to suppress the postoperative local and distant relapse of TNBC tumors.

An Injectable Puerarin Depot Can Potentiate Chimeric Antigen Receptor Natural Killer Cell Immunotherapy Against Targeted Solid Tumors by Reversing Tumor Immunosuppression

Chimeric antigen receptor natural killer (CAR-NK) cell therapy represents a potent approach to suppressing tumor growth because it has simultaneously inherited the specificity of CAR and the intrinsic generality of NK cells in recognizing cancer cells. However, its therapeutic potency against solid tumors is still restricted by insufficient tumor infiltration, immunosuppressive tumor microenvironments, and many other biological barriers. Motivated by the high potency of puerarin, a traditional Chinese medicine extract, in dilating tumor blood vessels, an injectable puerarin depot based on a hydrogen peroxide-responsive hydrogel comprising poly(ethylene glycol) dimethacrylate and ferrous chloride is concisely developed. Upon intratumoral fixation, the as-prepared puerarin depot (abbreviated as puerarin@PEGel) can activate nitrogen oxide production inside endothelial cells and thus dilate tumor blood vessels to relieve tumor hypoxia and reverse tumor immunosuppression. Such treatment can thus promote tumor infiltration, survival, and effector functions of customized epidermal growth factor receptor (HER1)-targeted HER1-CAR-NK cells after intravenous administration. Consequently, such puerarin@PEGel-assisted HER1-CAR-NK cell treatment exhibits superior tumor suppression efficacy toward both HER1-overexpressing MDA-MB-468 and NCI-H23 human tumor xenografts in mice without inducing obvious side effects. This study highlights a potent strategy to activate CAR-NK cells for augmented treatment of targeted solid tumors through reprogramming tumor immunosuppression.

Unraveling Biomarker Signatures in Triple-Negative Breast Cancer: A Systematic Review for Targeted Approaches

Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer, marked by poor outcomes and dismal prognosis. Due to the absence of targetable receptors, chemotherapy still represents the main therapeutic option. Therefore, current research is now focusing on understanding the specific molecular pathways implicated in TNBC, in order to identify novel biomarker signatures and develop targeted therapies able to improve its clinical management. With the aim of identifying novel molecular features characterizing TNBC, elucidating the mechanisms by which these molecular biomarkers are implicated in the tumor development and progression, and assessing the impact on cancerous cells following their inhibition or modulation, we conducted a literature search from the earliest works to December 2023 on PubMed, Scopus, and Web Of Science. A total of 146 studies were selected. The results obtained demonstrated that TNBC is characterized by a heterogeneous molecular profile. Several biomarkers have proven not only to be characteristic of TNBC but also to serve as potential effective therapeutic targets, holding the promise of a new era of personalized treatments able to improve its prognosis. The pre-clinical findings that have emerged from our systematic review set the stage for further investigation in forthcoming clinical trials.

The role and function of CLU in cancer biology and therapy

Clusterin (CLU) is a highly evolutionary conserved glycoprotein with multiple isoform-specific functions and is widely distributed in different species. Accumulated evidence has shown the prominent role of CLU in regulating several essential physiological processes, including programmed cell death, metastasis, invasion, proliferation and cell growth via regulating diverse signaling pathways to mediate cancer progression in various cancers, such as prostate, breast, lung, liver, colon, bladder and pancreatic cancer. Several studies have revealed the potential benefit of inhibiting CLU in CLU inhibition-based targeted cancer therapies in vitro, in vivo or in human, suggesting CLU is a promising therapeutic target. This review discusses the multiple functions and mechanisms of CLU in regulating tumor progression of various cancers and summarizes the inhibitors of CLU used in CLU inhibition-based targeted cancer therapies.

Clusterin Is a Prognostic Biomarker of Lower-Grade Gliomas and Is Associated with Immune Cell Infiltration

Dysregulation of clusterin (CLU) has been demonstrated in many cancers and has been proposed as a regulator of carcinogenesis. However, the roles of CLU in gliomas remain unclear. The expression of CLU was assessed using TIMER2.0, GEPIA2, and R package 4.2.1 software, leveraging data from TCGA and/or GTEx databases. Survival analysis and Cox regression were employed to investigate the prognostic significance of CLU. Immune infiltration was evaluated utilizing TIMER2.0, ESTIMATE, and CIBERSORT. The findings reveal the dysregulated expression of CLU in many cancers, with a marked increase observed in glioblastoma and lower-grade glioma (LGG). High CLU expression indicated worse survival outcomes and was an independent risk factor for the prognosis in LGG patients. CLU was involved in immune status as evidenced by its strong correlations with immune and stromal scores and the infiltration levels of multiple immune cells. Additionally, CLU was co-expressed with multiple immune-related genes, and high CLU expression was associated with the activation of immune-related pathways, such as binding to the antigen/immunoglobulin receptor and aiding the cytokine and cytokine receptor interaction. In conclusion, CLU appears to play crucial roles in tumor immunity within gliomas, highlighting its potential as a biomarker or target in glioma immunotherapy.

Membrane trafficking in breast cancer progression: protein kinase D comes into play

Protein kinase D (PKD) is a serine/threonine kinase family that controls important cellular functions, most notably playing a key role in the secretory pathway at the trans-Golgi network. Aberrant expression of PKD isoforms has been found mainly in breast cancer, where it promotes various cellular processes such as growth, invasion, survival and stem cell maintenance. In this review, we discuss the isoform-specific functions of PKD in breast cancer progression, with a particular focus on how the PKD controlled cellular processes might be linked to deregulated membrane trafficking and secretion. We further highlight the challenges of a therapeutic approach targeting PKD to prevent breast cancer progression.

Clusterin is a biomarker of breast cancer prognosis and correlated with immune microenvironment

Background

It has been established that clusterin is involved in the invasion of immune cells in the tumor microenvironment, but it remains unknown how it promotes immune invasion in breast cancer.

Methods

We used Tumor Immune Estimation Resource (TIMER) and Gene Expression Profiling Interactive Analysis (GEPIA) databases to assess the relation between expression of clusterin and immunoinfiltration-related marker genes. TIMER database was used to evaluate the expression of clusterin, and its relation to tumor immune invasion was examined. Based on Kaplan-Meier plotter database, we investigated the association between clusterin expression and prognosis in patients with cancer, and the impact of clinicopathological factors and cancer-related outcomes.

Results

Clusterin expression was markedly associated with prognosis of a variety of tumors, specifically breast cancer. Enhanced clusterin expression was markedly associated with molecular typing of breast cancer and expression of multiple markers related to specific immune cell subsets.

Conclusions

These results indicate that clusterin is connected to prognosis of breast cancer patients and tumor immune cell infiltration. This demonstrates that clusterin may be a biomarker of immune cell recruitment into breast tumors and an important biomarker for immune cell infiltration; consequently being a valuable prognostic factor in breast cancer patients.

Small Molecule Inhibitors of Protein Kinase D: Early Development, Current Approaches, and Future Directions

Now entering its fourth decade, research on the biological function, small molecule inhibition, and disease relevance of the three known isoforms of protein kinase D, PKD1, PKD2, and PKD3, has entered a mature development stage. This mini-perspective focuses on the medicinal chemistry that provided a structurally diverse set of mainly active site inhibitors, which, for a brief time period, moved through preclinical development stages but have yet to be tested in clinical trials. In particular, between 2006 and 2012, a rapid expansion of synthetic efforts led to several moderately to highly PKD-selective chemotypes but did not yet achieve PKD subtype selectivity or resolve general toxicity and pharmacokinetic challenges. In addition to cancer, other unresolved medical needs in cardiovascular, inflammatory, and metabolic diseases would, however, benefit from a renewed focus on potent and selective PKD modulators.

Clusterin negatively modulates mechanical stress-mediated ligamentum flavum hypertrophy through TGF-β1 signaling

Ligamentum flavum hypertrophy (LFH) is a major cause of lumbar spinal canal stenosis (LSCS). The pathomechanisms for LFH have not been fully elucidated. Isobaric tags for relative and absolute quantitation (iTRAQ) technology, proteomics assessments of human ligamentum flavum (LF), and successive assays were performed to explore the effect of clusterin (CLU) upregulation on LFH pathogenesis. LFH samples exhibited higher cell positive rates of the CLU, TGF-β1, α-SMA, ALK5 and p-SMAD3 proteins than non-LFH samples. Mechanical stress and TGF-β1 initiated CLU expression in LF cells. Notably, CLU inhibited the expression of mechanical stress-stimulated and TGF-β1-stimulated COL1A2 and α-SMA. Mechanistic studies showed that CLU inhibited mechanical stress-stimulated and TGF-β1-induced SMAD3 activities through suppression of the phosphorylation of SMAD3 and by inhibiting its nuclear translocation by competitively binding to ALK5. PRKD3 stabilized CLU protein by inhibiting lysosomal distribution and degradation of CLU. CLU attenuated mechanical stress-induced LFH in vivo. In summary, the findings showed that CLU attenuates mechanical stress-induced LFH by modulating the TGF-β1 pathways in vitro and in vivo. These findings imply that CLU is induced by mechanical stress and TGF-β1 and inhibits LF fibrotic responses via negative feedback regulation of the TGF-β1 pathway. These findings indicate that CLU is a potential treatment target for LFH.

The protein clusterin regulates the body’s response to lower back pain induced by mechanical stress and could be a target for treatments. Lower back pain is common and is exacerbated by our upright stance. A major cause of the pain is excessive cell growth (hypertrophy) in the ligaments between vertebrae. This growth narrows the spinal canal and compresses nerves. Using a unique mouse model bred to walk upright, Zhongmin Zhang and Liang Wang at Southern Medical University in Guangzhou, China, and co-workers showed that clusterin, a protein involved in regulation of cell survival, can reduce the hypertrophy caused by mechanical stresses, and could be used in back pain treatments. Clusterin regulates the activity of the growth factor TGF-β1, which plays a role in synthesizing new tissues after injury, but can spur excessive growth.

Nanomediator-Effector Cascade Systems for Amplified Protein Kinase Activity Imaging and Phosphorylation-Induced Drug Release In Vivo

Protein kinases constitute a rich pool of biomarkers and therapeutic targets of tremendous diseases including cancer. However, sensing kinase activity in vivo while implementing treatments according to kinase hyperactivation remains challenging. Herein, we present a nanomediator-effector cascade system that can in situ magnify the subtle events of kinase-catalyzed phosphorylation via DNA amplification machinery to achieve kinase activity imaging and kinase-responsive drug release in vivo. In this cascade, the phosphorylation-mediated disassembly of DNA/peptide complex on the nanomediators initiated the detachment of fluorescent hairpin DNAs from the nanoeffectors via hybridization chain reaction (HCR), leading to fluorescence recovery and therapeutic cargo release. We demonstrated that this nanosystem simultaneously enabled trace protein kinase A (PKA) activity imaging and on-demand drug delivery for inhibition of tumor cell growth both in vitro and in vivo, affording a kinase-specific sense-and-treat paradigm for cancer theranostics.