Plexin-B1 Mutation Drives Metastasis in Prostate Cancer Mouse Models

A combined immune and exosome-related risk signature as prognostic biomakers in acute myeloid leukemia

OBJECTIVES

Acute myeloid leukemia (AML) is one of the common hematological diseases with low survival rates. Studies have highlighted the dysregulated expression of immune-related and exosome-related genes (ERGs) in cancers. Nevertheless, it remains to be determined whether combining these genes have a prognostic significance in AML.

METHODS

Immune-ERG profiles for 151 AML patients from TCGA were analyzed. A risk model was constructed and optimized through the combination of univariate Cox regression and LASSO regression analysis. GEO datasets were utilized as the external validation for the robustness of the risk model. In addition, we performed KEGG and GO enrichment analyses to investigate the role played by these genes in AML. The variations in immune cell infiltrations among risk groups were assessed through four algorithms. Expression of hub gene in specific cell was analyzed by single-cell RNA seq.

RESULTS

A total of 85 immune-ERGs associated with prognosis were identified, enabling the construction of a risk model for AML. The risk model based on five immune-ERGs (CD37, NUCB2, LSP1, MGST1, and PLXNB1) demonstrated a correlation with the clinical outcomes. Additionally, age, FAB classification, cytogenetics risk, and risk score were identified as independent prognostic factors. The five immune-ERGs exhibited correlations with cytokine-cytokine receptor interaction, and antigen processing and presentation. Notably, the risk model demonstrated significant associations with immune responses and the expression of immune checkpoints.

CONCLUSIONS

An immune-ERG-based risk model was developed to effectively predict prognostic outcomes for AML patients. There is potential for immune therapy in AML targeting the five hub genes.

The metastasis-promoting P1597L mutation in PlexinB1 enhances Ras activity

BACKGROUND

Metastatic prostate cancer is a leading cause of cancer-related morbidity and mortality in men, yet the underlying molecular mechanisms are poorly understood. Plexins are transmembrane receptors for semaphorins with divergent roles in many forms of cancer. We recently found that a single clinically relevant specific amino acid change (Proline1597Leucine, (P1597L)), found in metastatic deposits of prostate cancer patients, converts PlexinB1 from a metastasis suppressor to a gene that drives prostate cancer metastasis in vivo. However, the mechanism by which PlexinB1(P1597L) promotes metastasis is not known.

METHODS

Pull down assays using GST-RalGDS or -GSTRaf1-RBD were used to reveal the effect of mutant or wild-type PlexinB1 expression on Rap and Ras activity respectively. Protein-protein interactions were assessed in GST pulldown assays, Akt/ERK phosphorylation by immunoblotting and protein stability by treatment with cycloheximide. Rho/ROCK activity was monitored by measuring MLC2 phosphorylation and actin stress fiber formation. PlexinB1 function was measured using cell-collapse assays.

RESULTS

We show here that the single clinically relevant P1597L amino acid change converts PlexinB1 from a repressor of Ras to a Ras activator. The PlexinB1(P1597L) mutation inhibits the RapGAP activity of PlexinB1, promoting a significant increase in Ras activity. The P1597L mutation also blocks PlexinB1-mediated reduction in Rho/ROCK activity, restraining the decrease in MLC2 phosphorylation and actin stress fiber formation induced by overexpression of wild-type PlexinB1. PlexinB1(P1597L) has little effect on the interaction of PlexinB1 with small GTPases or receptor tyrosine kinases and does not inhibit PlexinB1-stimulated Akt or ERK phosphorylation. These results indicate that the mutation affects Rho signalling via the Rap/Ras pathway. The PlexinB1(P1597L) mutation inhibits morphological cell collapse induced by wild-type PlexinB1 expression, suggesting that the mutation induces a loss of an inhibitory tumour suppressor function.

CONCLUSION

These results suggest that the clinically relevant P1597L mutation in PlexinB1 may transform PlexinB1 from a suppressor to a driver of metastasis in mouse models of prostate cancer by reducing the RapGAP activity of PlexinB1, leading to Ras activation. These findings highlight the PlexinB1-Rap-Ras pathway for therapeutic intervention in prostate cancer.

Cancer Metastasis-on-a-Chip for Modeling Metastatic Cascade and Drug Screening

Microfluidic chips are valuable tools for studying intricate cellular and cell-microenvironment interactions. Traditional in vitro cancer models lack accuracy in mimicking the complexities of in vivo tumor microenvironment. However, cancer-metastasis-on-a-chip (CMoC) models combine the advantages of 3D cultures and microfluidic technology, serving as powerful platforms for exploring cancer mechanisms and facilitating drug screening. These chips are able to compartmentalize the metastatic cascade, deepening the understanding of its underlying mechanisms. This article provides an overview of current CMoC models, focusing on distinctive models that simulate invasion, intravasation, circulation, extravasation, and colonization, and their applications in drug screening. Furthermore, challenges faced by CMoC and microfluidic technologies are discussed, while exploring promising future directions in cancer research. The ongoing development and integration of these models into cancer studies are expected to drive transformative advancements in the field.

The intricate dance of tumor evolution: Exploring immune escape, tumor migration, drug resistance, and treatment strategies

Recent research has unveiled fascinating insights into the intricate mechanisms governing tumor evolution. These studies have illuminated how tumors adapt and proliferate by exploiting various factors, including immune evasion, resistance to therapeutic drugs, genetic mutations, and their ability to adapt to different environments. Furthermore, investigations into tumor heterogeneity and chromosomal aberrations have revealed the profound complexity that underlies the evolution of cancer. Emerging findings have also underscored the role of viral influences in the development and progression of cancer, introducing an additional layer of complexity to the field of oncology. Tumor evolution is a dynamic and complex process influenced by various factors, including immune evasion, drug resistance, tumor heterogeneity, and viral influences. Understanding these elements is indispensable for developing more effective treatments and advancing cancer therapies. A holistic approach to studying and addressing tumor evolution is crucial in the ongoing battle against cancer. The main goal of this comprehensive review is to explore the intricate relationship between tumor evolution and critical aspects of cancer biology. By delving into this complex interplay, we aim to provide a profound understanding of how tumors evolve, adapt, and respond to treatment strategies. This review underscores the pivotal importance of comprehending tumor evolution in shaping effective approaches to cancer treatment.