PRL-3 exerts oncogenic functions in myeloid leukemia cells via aberrant dephosphorylation of stathmin and activation of STAT3 signaling

PRL-3: unveiling a new horizon in cancer therapy

PRL-3, a protein tyrosine phosphatase (PTP), has a significant influence on the pathogenesis of various cancers with its overexpression significantly correlating with tumor invasion, metastasis and poor prognosis. It significantly affects tumor cell behavior through its involvement in cell proliferation, migration and metabolic processes. Furthermore, the interaction between PRL-3 and the tumor microenvironment characterized by its adaptability to stress and its role in metabolic reprogramming enhances tumor cell survival and dissemination. Targeted therapies against PRL-3, encompassing small molecule inhibitors and the monoclonal antibody PRL-3-zumab, have shown promise in clinical and preclinical studies, presenting new avenues for cancer treatment. In addition, innovative approaches such as CAAX motif-targeting agents and PRL-3 degradation strategies hold promise for developing more precise and effective interventions. This review explores PRL-3's multifaceted roles across different tumor types and microenvironments, while discussing current and emerging therapeutic strategies aimed at exploiting its oncogenic potential.

Deletion of PTP4A3 phosphatase in high-grade serous ovarian cancer cells decreases tumorigenicity and produces marked changes in intracellular signaling pathways and cytokine release

The oncogenic protein tyrosine phosphatase PTP4A3 is frequently overexpressed in human ovarian cancers and is associated with poor patient prognosis. PTP4A3 is thought to regulate multiple oncogenic signaling pathways, including STAT3, SRC, and extracellular signal-regulated kinase. The objective of this study was to generate ovarian cancer cells with genetically depleted PTP4A3, to assess their tumorigenicity, to examine their cellular phenotype, and to uncover changes in their intracellular signaling pathways and cytokine release profiles. Genetic deletion of PTP4A3 using CRISPR/CRISPR-associated protein 9 enabled the generation of individual clones derived from single cells isolated from the polyclonal knockout population. We observed a >90% depletion of PTP4A3 protein levels by western blotting in the clonal cell lines compared with the sham-transfected wild-type population. The wild-type and polyclonal knockout cell lines shared similar monolayer growth rates, whereas the isolated clonal populations 2B4, 3C9, and 3C12 exhibited significantly lower monolayer growth characteristics consistent with their lower PTP4A3 levels. The clonal Ptp4a3 knockout cell lines also had substantially lower in vitro colony formation efficiencies compared with the wild-type cells and were less tumorigenic in vivo. The clonal knockout cells were markedly less responsive to interleukin-6-stimulated migration in a scratch wound assay compared with the wild-type cells. Antibody microarray assays documented differences in cytokine release and intracellular phosphorylation patterns in the Ptp4a3-deleted clones. Bioinformatic network analyses indicated alterations in cellular signaling nodes. These biochemical changes could ultimately form the foundation for pharmacodynamic endpoints useful for emerging anti-PTP4A3 therapeutics. SIGNIFICANCE STATEMENT: Clones of high-grade serous ovarian cancer cells were isolated, in which the oncogenic phosphatase Ptp4a3 gene was deleted using CRISPR/CRISPR-associated protein 9 methodologies. The Ptp4a3-null cells exhibited loss of in vitro proliferation, colony formation, and migration and reduced in vivo tumorigenesis. Marked differences in intracellular protein phosphorylation and cytokine release were seen. The newly developed Ptp4a3 knockout cells should provide useful tools to probe the role of PTP4A3 phosphatase in ovarian cancer cell survival, tumorigenicity, and cell signaling.

Protein Tyrosine Phosphatase PRL-3: A Key Player in Cancer Signaling

Protein phosphatases are primarily responsible for dephosphorylation modification within signal transduction pathways. Phosphatase of regenerating liver-3 (PRL-3) is a dual-specific phosphatase implicated in cancer pathogenesis. Understanding PRL-3's intricate functions and developing targeted therapies is crucial for advancing cancer treatment. This review highlights its regulatory mechanisms, expression patterns, and multifaceted roles in cancer progression. PRL-3's involvement in proliferation, migration, invasion, metastasis, angiogenesis, and drug resistance is discussed. Regulatory mechanisms encompass transcriptional control, alternative splicing, and post-translational modifications. PRL-3 exhibits selective expressions in specific cancer types, making it a potential target for therapy. Despite advances in small molecule inhibitors, further research is needed for clinical application. PRL-3-zumab, a humanized antibody, shows promise in preclinical studies and clinical trials. Our review summarizes the current understanding of the cancer-related cellular function of PRL-3, its prognostic value, and the research progress of therapeutic inhibitors.

STNM1 in human cancers: role, function and potential therapy sensitizer

STMN1 belongs to the stathmin gene family, it encodes a cytoplasmic phosphorylated protein, stathmin1, which is commonly observed in vertebrate cells. STMN1 is a structural microtubule-associated protein (MAP) that binds to microtubule protein dimers rather than microtubules, with each STMN1 binding two microtubule protein dimers and preventing their aggregation, leading to microtubule instability. STMN1 expression is elevated in a number of malignancies, and inhibition of its expression can interfere with tumor cell division. Its expression can change the division of tumor cells, thereby arresting cell growth in the G2/M phase. Moreover, STMN1 expression affects tumor cell sensitivity to anti-microtubule drug analogs, including vincristine and paclitaxel. The research on MAPs is limited, and new insights on the mechanism of STMN1 in different cancers are emerging. The effective application of STMN1 in cancer prognosis and treatment requires further understanding of this protein. Here, we summarize the general characteristics of STMN1 and outline how STMN1 plays a role in cancer development, targeting multiple signaling networks and acting as a downstream target for multiple microRNAs, circRNAs, and lincRNAs. We also summarize recent findings on the function role of STMN1 in tumor resistance and as a therapeutic target for cancer.

PRL3 as a therapeutic target for novel cancer immunotherapy in multiple cancer types

Phosphatase of Regenerating Liver-3 (PRL3) was discovered in 1998 and was subsequently found to be correlated with cancer progression and metastasis in 2001. Extensive research in the past two decades has produced significant findings on PRL3-mediated cancer signaling and functions, as well as its clinical relevance in diverse types of cancer. PRL3 has been established to play a role in many cancer-related functions, including but not limited to metastasis, proliferation, and angiogenesis. Importantly, the tumor-specific expression of PRL3 protein in multiple cancer types has made it an attractive therapeutic target. Much effort has been made in developing PRL3-targeted therapy with small chemical inhibitors against intracellular PRL3, and notably, the development of PRL3-zumab as a novel cancer immunotherapy against PRL3. In this review, we summarize the current understanding of the role of PRL3 in cancer-related cellular functions, its prognostic value, as well as perspectives on PRL3 as a target for unconventional immunotherapy in the clinic with PRL3-zumab.

Phosphoproteomic Analysis Reveals Downstream PKA Effectors of AKAP Cypher/ZASP in the Pathogenesis of Dilated Cardiomyopathy

Background: Dilated cardiomyopathy (DCM) is a major cause of heart failure worldwide. The Z-line protein Cypher/Z-band alternatively spliced PDZ-motif protein (ZASP) is closely associated with DCM, both clinically and in animal models. Our earlier work revealed Cypher/ZASP as a PKA-anchoring protein (AKAP) that tethers PKA to phosphorylate target substrates. However, the downstream PKA effectors regulated by AKAP Cypher/ZASP and their relevance to DCM remain largely unknown.

Methods and Results: For the identification of candidate PKA substrates, global quantitative phosphoproteomics was performed on cardiac tissue from wild-type and Cypher-knockout mice with PKA activation. A total of 216 phosphopeptides were differentially expressed in the Cypher-knockout mice; 31 phosphorylation sites were selected as candidates using the PKA consensus motifs. Bioinformatic analysis indicated that differentially expressed proteins were enriched mostly in cell adhesion and mRNA processing. Furthermore, the phosphorylation of β-catenin Ser675 was verified to be facilitated by Cypher. This phosphorylation promoted the transcriptional activity of β-catenin, and also the proliferative capacity of cardiomyocytes. Immunofluorescence staining demonstrated that Cypher colocalised with β-catenin in the intercalated discs (ICD) and altered the cytoplasmic distribution of β-catenin. Moreover, the phosphorylation of two other PKA substrates, vimentin Ser72 and troponin I Ser23/24, was suppressed by Cypher deletion.

Conclusions: Cypher/ZASP plays an essential role in β-catenin activation via Ser675 phosphorylation, which modulates cardiomyocyte proliferation. Additionally, Cypher/ZASP regulates other PKA effectors, such as vimentin Ser72 and troponin I Ser23/24. These findings establish the AKAP Cypher/ZASP as a signalling hub in the progression of DCM.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.