Emerging role of microtubule-associated proteins on cancer metastasis

Discovery of Novel Diaryl-Substituted Fused Heterocycles Targeting Katanin and Tubulin with Potent Antitumor and Antimultidrug Resistance Efficacy

Disrupting microtubule dynamics has emerged as a promising strategy for cancer treatment. However, drug resistance remains a challenge hindering the development of microtubule-targeting agents. In this work, a novel class of diaryl substituted fused heterocycles were designed, synthesized, and evaluated, which were demonstrated as effective dual katanin and tubulin regulators with antitumor activity. Following three rounds of stepwise optimization, compound 21b, featuring a 3H-imidazo[4,5-b]pyridine core, displayed excellent targeting capabilities on katanin and tubulin, along with notable antiproliferative and antimetastatic effects. Mechanistic studies revealed that 21b disrupts the microtubule network in tumor cells, leading to G2/M cell cycle arrest and apoptosis induction. Importantly, 21b exhibited significant inhibition of tumor growth in MDA-MB-231 and A549/T xenograft tumor models without evident toxicity and side effects. In conclusion, compound 21b presents a novel mechanism for disrupting microtubule dynamics, warranting further investigation as a dual-targeted antitumor agent with potential antimultidrug resistance properties.

A prospective study of HER3 expression pre and post neoadjuvant therapy of different breast cancer subtypes: implications for HER3 imaging therapy guidance

PURPOSE

HER3, a member of the EGFR receptor family, plays a central role in driving oncogenic cell proliferation in breast cancer. Novel HER3 therapeutics are showing promising results while recently developed HER3 PET imaging modalities aid in predicting and assessing early treatment response. However, baseline HER3 expression, as well as changes in expression while on neoadjuvant therapy, have not been well-characterized. We conducted a prospective clinical study, pre- and post-neoadjuvant/systemic therapy, in patients with newly diagnosed breast cancer to determine HER3 expression, and to identify possible resistance mechanisms maintained through the HER3 receptor.

EXPERIMENTAL DESIGN

The study was conducted between May 25, 2018 and October 12, 2019. Thirty-four patients with newly diagnosed breast cancer of any subtype (ER ± , PR ± , HER2 ±) were enrolled in the study. Two core biopsy specimens were obtained from each patient at the time of diagnosis. Four patients underwent a second research biopsy following initiation of neoadjuvant/systemic therapy or systemic therapy which we define as neoadjuvant therapy. Molecular characterization of HER3 and downstream signaling nodes of the PI3K/AKT and MAPK pathways pre- and post-initiation of therapy was performed. Transcriptional validation of finings was performed in an external dataset (GSE122630).

RESULTS

Variable baseline HER3 expression was found in newly diagnosed breast cancer and correlated positively with pAKT across subtypes (r = 0.45). In patients receiving neoadjuvant/systemic therapy, changes in HER3 expression were variable. In a hormone receptor-positive (ER +/PR +/HER2-) patient, there was a statistically significant increase in HER3 expression post neoadjuvant therapy, while there was no significant change in HER3 expression in a ER +/PR +/HER2+ patient. However, both of these patients showed increased downstream signaling in the PI3K/AKT pathway. One subject with ER +/PR -/HER2- breast cancer and another subject with ER +/PR +/HER2 + breast cancer showed decreased HER3 expression. Transcriptomic findings, revealed an immune suppressive environment in patients with decreased HER3 expression post therapy.

CONCLUSION

This study demonstrates variable HER3 expression across breast cancer subtypes. HER3 expression can be assessed early, post-neoadjuvant therapy, providing valuable insight into cancer biology and potentially serving as a prognostic biomarker. Clinical translation of neoadjuvant therapy assessment can be achieved using HER3 PET imaging, offering real-time information on tumor biology and guiding personalized treatment for breast cancer patients.

CAMSAP3-mediated regulation of HMGB1 acetylation and subcellular localization in lung cancer cells: Implications for cell death modulation

BACKGROUND

Deregulation of cell death is a common characteristic of cancer, and resistance to this process often occurs in lung cancer. Understanding the molecular mechanisms underlying an aberrant cell death is important. Recent studies have emphasized the involvement of calmodulin-regulated spectrin-associated protein 3 (CAMSAP3) in lung cancer aggressiveness, its influence on cell death regulation remains largely unexplored.

METHODS

CAMSAP3 was knockout in lung cancer cells using CRISPR-Cas9 system. Cell death and autophagy were evaluated using MTT and autophagic detection assays. Protein interactions were performed by proteomic analysis and immunoprecipitation. Protein expressions and their cytoplasmic localization were analyzed through immunoblotting and immunofluorescence techniques.

RESULTS

This study reveals a significant correlation between low CAMSAP3 expression and poor overall survival rates in lung cancer patients. Proteomic analysis identified high mobility group box 1 (HMGB1) as a candidate interacting protein involved in the regulation of cell death. Treatment with trichostatin A (TSA), an inhibitor of histone deacetylases (HDACs) resulted in increased HMGB1 acetylation and its translocation to the cytoplasm and secretion, thereby inducing autophagic cell death. However, this process was diminished in CAMSAP3 knockout lung cancer cells. Mechanistically, immunoprecipitation indicated an interaction between CAMSAP3 and HMGB1, particularly with its acetylated form, in which this complex was elevated in the presence of TSA.

CONCLUSIONS

CAMSAP3 is prerequisite for TSA-mediated autophagic cell death by interacting with cytoplasmic acetylated HMGB1 and enhancing its release.

SIGNIFICANT

This finding provides molecular insights into the role of CAMSAP3 in regulating cell death, highlighting its potential as a therapeutic target for lung cancer treatment.

Updates in pharmacotherapy for non-small cell lung cancer: a focus on emerging tubulin inhibitors

INTRODUCTION

The treatment landscape of non-small cell lung cancer (NSCLC) has seen significant advancements in recent years, marked by a shift toward target agents and immune checkpoint inhibitors (ICIs). However, chemotherapy remains a cornerstone of treatment, alone or in combination. Microtubule-targeting agents, such as taxanes and vinca alkaloids, play a crucial role in clinical practice in both early and advanced settings in NSCLC.

AREA COVERED

This review outlines the mechanisms of action, present significance, and prospective advancements of microtubule-targeting agents (MTAs), with a special highlight on new combinations in phase 3 trials. The online databases PubMed, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched using the terms 'Microtubule-targeting agents' and 'non-small cell lung cancer' or synonyms, with a special focus over the last 5 years of publications.

EXPERT OPINION

Despite the emergence of immunotherapy, MTA remains crucial, often used alongside or after immunotherapy, especially in squamous cell lung cancer. Next-generation sequencing expands treatment options, but reliable biomarkers for immunotherapy are lacking. While antibody-drug conjugates (ADCs) show promise, managing toxicities remain vital. In the early stages, MTAs, possibly with ICIs, are standard, while ADCs may replace traditional chemotherapy in the advanced stages. Nevertheless, MTAs remain essential in subsequent lines or for patients with contraindications.

The anticancer potential of the CLK kinases inhibitors 1C8 and GPS167 revealed by their impact on the epithelial-mesenchymal transition and the antiviral immune response

The diheteroarylamide-based compound 1C8 and the aminothiazole carboxamide-related compound GPS167 inhibit the CLK kinases, and affect the proliferation of a broad range of cancer cell lines. A chemogenomic screen previously performed with GPS167 revealed that the depletion of components associated with mitotic spindle assembly altered sensitivity to GPS167. Here, a similar screen performed with 1C8 also established the impact of components involved in mitotic spindle assembly. Accordingly, transcriptome analyses of cells treated with 1C8 and GPS167 indicated that the expression and RNA splicing of transcripts encoding mitotic spindle assembly components were affected. The functional relevance of the microtubule connection was confirmed by showing that subtoxic concentrations of drugs affecting mitotic spindle assembly increased sensitivity to GPS167. 1C8 and GPS167 impacted the expression and splicing of transcripts in pathways relevant to tumor progression, including MYC targets and the epithelial mesenchymal transition (EMT). Finally, 1C8 and GPS167 altered the expression and alternative splicing of transcripts involved in the antiviral immune response. Consistent with this observation, depleting the double-stranded RNA sensor DHX33 suppressed GPS167-mediated cytotoxicity on HCT116 cells. Our study uncovered molecular mechanisms through which 1C8 and GPS167 affect cancer cell proliferation as well as processes critical for metastasis.

MAP7 drives EMT and cisplatin resistance in ovarian cancer via wnt/β-catenin signaling

Methods

Our approach encompasses analyzing MAP7's expression levels across various datasets and clinical specimens, evaluating its association with patient outcomes, and probing its influence on ovarian cancer cell dynamics such as proliferation, migration, invasion, and apoptosis.

Results

We have identified significant upregulation of MAP7 in ovarian cancer tissues, which correlates with advanced disease stages, higher pathological grades, and unfavorable prognoses. Functionally, the inhibition of MAP7 suppresses cancer cell proliferation, migration, and invasion while promoting apoptosis. Notably, the silencing of MAP7 attenuates the epithelial-mesenchymal transition (EMT) and disrupts Wnt/β-catenin pathway signaling-two critical processes implicated in metastasis and chemoresistance. In cisplatin-resistant A2780-DDP cells, the downregulation of MAP7 effectively reverses their resistance to cisplatin. Furthermore, the nuclear localization of MAP7 in these cells underscores its pivotal role in driving cisplatin resistance by modulating the transcriptional regulation and interaction dynamics of β-catenin.

Conclusion

Our findings position MAP7 as a pivotal element in ovarian cancer advancement and cisplatin resistance, primarily through its modulation of EMT and the Wnt/β-catenin pathway. Its association with poor clinical outcomes underscores its potential as both a prognostic marker and a therapeutic target. Strategies aimed at MAP7 could represent a new frontier in combating chemotherapy resistance in ovarian cancer, emphasizing its significance in crafting complementary treatments for this disease.

CAMSAP2 enhances lung cancer cell metastasis by mediating RASAL2 degradation

AIMS

Cancer metastasis significantly contributes to mortality in lung cancer patients. Calmodulin-regulated spectrin-associated protein family member 2 (CAMSAP2) plays a significant role in cancer cell migration; however, its role in lung cancer metastasis and the underlying mechanism remain largely unknown. The present study aimed to investigate the impact of CAMSAP2 on lung cancer.

MAIN METHODS

The clinical relevance of CAMSAP2 in lung cancer patients was assessed using public database. RNA interference experiments were conducted to investigate role of CAMSAP2 in cell migration through transwell and wound healing assays. Molecular mechanisms were explored by identifying the possible interacting partners and pathways using the BioGRID and KEGG pathway analyses. The impact of CAMSAP2 on Ras protein activator-like 2 (RASAL2)-mediated lung cancer metastasis was investigated through biochemical assays. Additionally, in vivo experimentation using a murine tail vein metastasis model was performed to comprehend CAMSAP2's influence on metastasis.

KEY FINDINGS

A high expression level of CAMSAP2 was associated with poor overall survival in lung cancer patients and it positively correlated with cell migration in non-small cell lung cancer (NSCLC) cell lines. Knockdown of CAMSAP2 inhibited lung cancer cell motility in vitro and metastasis in vivo. Proteomic and biochemical analyses revealed the interaction between CAMSAP2 and RASAL2, which facilitates the degradation of RASAL2 through the ubiquitin-proteasome system. These degradation processes resulted in the activation of the extracellular signal-regulated kinase (ERK) signaling pathway, thereby promoting lung cancer metastasis. Collectively, the results of this study suggest that CAMSAP2 is a crucial regulator of cancer cell migration and metastasis and a promising therapeutic target for lung cancer.

Gene expression profiling and protein-protein network analysis revealed prognostic hub biomarkers linking cancer risk in type 2 diabetic patients

Type 2 diabetes mellitus (T2DM) and cancer are highly prevalent diseases imposing major health burden globally. Several epidemiological studies indicate increased susceptibility to cancer in T2DM patients. However, genetic factors linking T2DM with cancer have been poorly studied. In this study, we followed computational approaches using the raw gene expression data of peripheral blood mononuclear cells of T2DM and cancer patients available in the gene expression omnibus (GEO) database. Our analysis identified shared differentially expressed genes (DEGs) in T2DM and three common cancer types, namely, pancreatic cancer (PC), liver cancer (LC), and breast cancer (BC). The functional and pathway enrichment analysis of identified common DEGs highlighted the involvement of critical biological pathways, including cell cycle events, immune system processes, cell morphogenesis, gene expression, and metabolism. We retrieved the protein-protein interaction network for the top DEGs to deduce molecular-level interactions. The network analysis found 7, 6, and 5 common hub genes in T2DM vs. PC, T2DM vs. LC, and T2DM vs. BC comparisons, respectively. Overall, our analysis identified important genetic markers potentially able to predict the chances of PC, LC, and BC onset in T2DM patients.

A Network of 17 Microtubule-Related Genes Highlights Functional Deregulations in Breast Cancer

A wide panel of microtubule-associated proteins and kinases is involved in coordinated regulation of the microtubule cytoskeleton and may thus represent valuable molecular markers contributing to major cellular pathways deregulated in cancer. We previously identified a panel of 17 microtubule-related (MT-Rel) genes that are differentially expressed in breast tumors showing resistance to taxane-based chemotherapy. In the present study, we evaluated the expression, prognostic value and functional impact of these genes in breast cancer. We show that 14 MT-Rel genes (KIF4A, ASPM, KIF20A, KIF14, TPX2, KIF18B, KIFC1, AURKB, KIF2C, GTSE1, KIF15, KIF11, RACGAP1, STMN1) are up-regulated in breast tumors compared with adjacent normal tissue. Six of them (KIF4A, ASPM, KIF20A, KIF14, TPX2, KIF18B) are overexpressed by more than 10-fold in tumor samples and four of them (KIF11, AURKB, TPX2 and KIFC1) are essential for cell survival. Overexpression of all 14 genes, and underexpression of 3 other MT-Rel genes (MAST4, MAPT and MTUS1) are associated with poor breast cancer patient survival. A Systems Biology approach highlighted three major functional networks connecting the 17 MT-Rel genes and their partners, which are centered on spindle assembly, chromosome segregation and cytokinesis. Our studies identified mitotic Aurora kinases and their substrates as major targets for therapeutic approaches against breast cancer.

Expression of Genes Associated With Epithelial-Mesenchymal Transition in Merkel Cell Polyomavirus-Negative Merkel Cell Carcinoma

Two accepted possible pathways for Merkel cell carcinoma (MCC) pathogenesis include the clonal integration of the Merkel cell polyomavirus (MCPyV) into the neoplastic cells and by UV irradiation. We hypothesize that, in UV etiology, the expression of genes associated with epithelial-mesenchymal transition (EMT) would be higher in MCPyV-negative MCCs. We compared RNA expression in 16 MCPyV-negative with that in 14 MCPyV-positive MCCs in 30 patients using NanoString panel of 760 gene targets as an exploratory method. Subsequently, we confirmed the findings with a publicly available RNA sequencing data set. The NanoString method showed that 29 of 760 genes exhibited significant deregulation. Ten genes (CD44, COL6A3, COL11A1, CXCL8, INHBA, MMP1, NID2, SPP1, THBS1, and THY1) were part of the EMT pathway. The expression of CDH1/E-cadherin, a key EMT gene, and TWIST1, regulator gene of EMT, was higher in MCPyV-negative tumors. To further investigate the expression of EMT genes in MCPyV-negative MCCs, we analyzed publicly available RNA sequencing data of 111 primary MCCs. Differential expression and gene set enrichment analysis of 35 MCPyV-negative versus 76 MCPyV-positive MCCs demonstrated significantly higher expression of EMT-related genes and associated pathways such as Notch signaling, TGF-β signaling, and Hedgehog signaling, and UV response pathway in MCPyV-negative MCCs. The significance of the EMT pathway in MCPyV-negative MCCs was confirmed independently by a coexpression module analysis. One of the modules (M3) was specifically activated in MCPyV-negative MCCs and showed significant enrichment for genes involved in EMT. A network analysis of module M3 revealed that CDH1/E-cadherin was among the most connected genes (hubs). E-cadherin and LEF1 immunostains demonstrated significantly more frequent expression in MCPvV-negative versus MCPyV-positive tumors (P < .0001). In summary, our study showed that the expression of EMT-associated genes is higher in MCPyV-negative MCC. Because EMT-related proteins can be targeted, the identification of EMT pathways in MCPyV-negative MCCs is of potential therapeutic relevance.

CAMSAP3 negatively regulates lung cancer cell invasion and angiogenesis through nucleolin/HIF-1α mRNA complex stabilization

AIMS

Cancer metastasis is a major cause of lung cancer-related mortality, so identification of related molecular mechanisms is of interest. Calmodulin-regulated spectrin-associated protein 3 (CAMSAP3) has been implicated in lung cancer malignancies; however, its role in metastatic processes, including invasion and angiogenesis, is largely unknown.

MAIN METHOD

The clinical relevance of CAMSAP3 expression in lung cancer was evaluated. The relevance of CAMSAP3 expression to in vitro cell invasion and angiogenesis was assessed in human lung cancer cells and endothelial cells, respectively. The molecular mechanism was identified by qRT-PCR, immunoprecipitation, mass spectrometry, and RNA immunoprecipitation. The in vivo metastatic and angiogenic activities of lung cancer cells were assessed.

KEY FINDINGS

Low CAMSAP3 expression was found in malignant lung tissues and strongly correlated with a poor prognosis in lung adenocarcinoma (LUAD). CAMSAP3-knockout NSCLC exhibited high invasive ability, and CAMSAP3 knockout induced HUVEC proliferation and tube formation; these effects were significantly attenuated by reintroduction of exogenous wild-type CAMSAP3. Mechanistically, in the absence of CAMSAP3, the expression of hypoxia-inducible factor-1α (HIF-1α) was upregulated, which increased the levels of downstream HIF-1α targets such as vascular endothelial growth factor A (VEGFA) and matrix metalloproteinases (MMPs) 2 and 9. Proteomic analysis revealed that nucleolin (NCL) bound to CAMSAP3 to regulate HIF-1α mRNA stabilization. In addition, CAMSAP3-knockout lung cancer cells displayed highly aggressive behavior in metastasis and angiogenesis in vivo.

SIGNIFICANCE

This study reveals that CAMSAP3 plays a negative regulatory role in lung cancer cell metastatic behavior both in vitro and in vivo through NCL/HIF-1α mRNA complex stabilization.

Dynamic Regulation Genes at Microtubule Plus Ends: A Novel Class of Glioma Biomarkers

Simple Summary

Microtubule plus-end-related genes (MPERGs) encode a group of proteins that specifically aggregate at the microtubule plus ends to play critical biological roles in the cell cycle, cell movement, ciliogenesis, and neuronal development by coordinating microtubule assembly and dynamics; however, the MPERG correlations and their clinical significance in glioma are not fully understood. This study is the first to systematically analyze and define a seven-gene signature (CTTNBP2, KIF18A, NAV1, SLAIN2, SRCIN1, TRIO, and TTBK2) and nomogram model closely associated with clinical factors and the tumor microenvironment as a reliable and independent prognostic biomarker to guide personalized choices of immunotherapy and chemotherapy for glioma patients.

Abstract

Glioma is the most prevalent and aggressive primary nervous system tumor with an unfavorable prognosis. Microtubule plus-end-related genes (MPERGs) play critical biological roles in the cell cycle, cell movement, ciliogenesis, and neuronal development by coordinating microtubule assembly and dynamics. This research seeks to systematically explore the oncological characteristics of these genes in microtubule-enriched glioma, focusing on developing a novel MPERG-based prognostic signature to improve the prognosis and provide more treatment options for glioma patients. First, we thoroughly analyzed and identified 45 differentially expressed MPERGs in glioma. Based on these genes, glioma patients were well distinguished into two subgroups with survival and tumor microenvironment infiltration differences. Next, we further screened the independent prognostic genes (CTTNBP2, KIF18A, NAV1, SLAIN2, SRCIN1, TRIO, and TTBK2) using 36 prognostic-related differentially expressed MPERGs to construct a signature with risk stratification and prognostic prediction ability. An increased risk score was related to the malignant progression of glioma. Therefore, we also designed a nomogram model containing clinical factors to facilitate the clinical use of the risk signature. The prediction accuracy of the signature and nomogram model was verified using The Cancer Genome Atlas and Chinese Glioma Genome Atlas datasets. Finally, we examined the connection between the signature and tumor microenvironment. The signature positively correlated with tumor microenvironment infiltration, especially immunoinhibitors and the tumor mutation load, and negatively correlated with microsatellite instability and cancer stemness. More importantly, immune checkpoint blockade treatment and drug sensitivity analyses confirmed that this prognostic signature was helpful in anticipating the effect of immunotherapy and chemotherapy. In conclusion, this research is the first study to define and validate an MPERG-based signature closely associated with the tumor microenvironment as a reliable and independent prognostic biomarker to guide personalized choices of immunotherapy and chemotherapy for glioma patients.

Alterations of Cytoskeleton Networks in Cell Fate Determination and Cancer Development

Cytoskeleton proteins have been long recognized as structural proteins that provide the necessary mechanical architecture for cell development and tissue homeostasis. With the completion of the cancer genome project, scientists were surprised to learn that huge numbers of mutated genes are annotated as cytoskeletal or associated proteins. Although most of these mutations are considered as passenger mutations during cancer development and evolution, some genes show high mutation rates that can even determine clinical outcomes. In addition, (phospho)proteomics study confirms that many cytoskeleton-associated proteins, e.g., β-catenin, PIK3CA, and MB21D2, are important signaling mediators, further suggesting their biofunctional roles in cancer development. With emerging evidence to indicate the involvement of mechanotransduction in stemness formation and cell differentiation, mutations in these key cytoskeleton components may change the physical/mechanical properties of the cells and determine the cell fate during cancer development. In particular, tumor microenvironment remodeling triggered by such alterations has been known to play important roles in autophagy, metabolism, cancer dormancy, and immune evasion. In this review paper, we will highlight the current understanding of how aberrant cytoskeleton networks affect cancer behaviors and cellular functions through mechanotransduction.

Evaluating the Expression and Prognostic Value of Genes Encoding Microtubule-Associated Proteins in Lung Cancer

Microtubule-associated proteins (MAPs) play essential roles in cancer development. This study aimed to identify transcriptomic biomarkers among MAP genes for the diagnosis and prognosis of lung cancer by analyzing differential gene expressions and correlations with tumor progression. Gene expression data of patients with lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) from the Cancer Genome Atlas (TCGA) database were used to identify differentially expressed MAP genes (DEMGs). Their prognostic value was evaluated by Kaplan-Meier and Cox regression analysis. Moreover, the relationships between alterations in lung cancer hallmark genes and the expression levels of DEMGs were investigated. The candidate biomarker genes were validated using three independent datasets from the Gene Expression Omnibus (GEO) database and by quantitative reverse transcription polymerase chain reaction (qRT-PCR) on clinical samples. A total of 88 DEMGs were identified from TCGA data. The 20 that showed the highest differential expression were subjected to association analysis with hallmark genes. Genetic alterations in TP53, EGFR, PTEN, NTRK1, and PIK3CA correlated with the expression of most of these DEMGs. Of these, six candidates-NUF2, KIF4A, KIF18B, DLGAP5, NEK2, and LRRK2-were significantly differentially expressed and correlated with the overall survival (OS) of the patients. The mRNA expression profiles of these candidates were consistently verified using three GEO datasets and qRT-PCR on patient lung tissues. The expression levels of NUF2, KIF4A, KIF18B, DLGAP5, NEK2, and LRRK2 can serve as diagnostic biomarkers for LUAD and LUSC. Moreover, the first five can serve as prognostic biomarkers for LUAD, while LRRK2 can be a prognostic biomarker for LUSC. Our research describes the novel role and potential application of MAP-encoding genes in clinical practice.

Cytoskeletal and Cytoskeleton-Associated Proteins: Key Regulators of Cancer Stem Cell Properties

Cancer stem cells (CSCs) are a subpopulation of cancer cells possessing stemness characteristics that are closely associated with tumor proliferation, recurrence and resistance to therapy. Recent studies have shown that different cytoskeletal components and remodeling processes have a profound impact on the behavior of CSCs. In this review, we outline the different cytoskeletal components regulating the properties of CSCs and discuss current and ongoing therapeutic strategies targeting the cytoskeleton. Given the many challenges currently faced in targeted cancer therapy, a deeper comprehension of the molecular events involved in the interaction of the cytoskeleton and CSCs will help us identify more effective therapeutic strategies to eliminate CSCs and ultimately improve patient survival.