Protein tyrosine phosphatase nonreceptor type 2 controls colorectal cancer development

Tumor microenvironment responsive nano-herb and CRISPR delivery system for synergistic chemotherapy and immunotherapy

Chemoresistance remains a significant challenge for effective breast cancer treatment which leads to cancer recurrence. CRISPR-directed gene editing becomes a powerful tool to reduce chemoresistance by reprogramming the tumor microenvironment. Previous research has revealed that Chinese herbal extracts have significant potential to overcome tumor chemoresistance. However, the therapeutic efficacy is often limited due to their poor tumor targeting and in vivo durability. Here we have developed a tumor microenvironment responsive nanoplatform (H-MnO2(ISL + DOX)-PTPN2@HA, M(I + D)PH) for nano-herb and CRISPR codelivery to reduce chemoresistance. Synergistic tumor inhibitory effects were achieved by the treatment of isoliquiritigenin (ISL) with doxorubicin (DOX), which were enhanced by CRISPR-based gene editing to target protein tyrosine phosphatase non-receptor type 2 (PTPN2) to initiate long-term immunotherapy. Efficient PTPN2 depletion was observed after treatment with M(I + D)PH nanoparticles, which resulted in the recruitment of intratumoral infiltrating lymphocytes and an increase of proinflammatory cytokines in the tumor tissue. Overall, our nanoparticle platform provides a diverse technique for accomplishing synergistic chemotherapy and immunotherapy, which offers an effective treatment alternative for malignant neoplasms.

Protein tyrosine phosphatases: emerging role in cancer therapy resistance

BACKGROUND

Tyrosine phosphorylation of intracellular proteins is a post-translational modification that plays a regulatory role in signal transduction during cellular events. Dephosphorylation of signal transduction proteins caused by protein tyrosine phosphatases (PTPs) contributed their role as a convergent node to mediate cross-talk between signaling pathways. In the context of cancer, PTP-mediated pathways have been identified as signaling hubs that enabled cancer cells to mitigate stress induced by clinical therapy. This is achieved by the promotion of constitutive activation of growth-stimulatory signaling pathways or modulation of the immune-suppressive tumor microenvironment. Preclinical evidences suggested that anticancer drugs will release their greatest therapeutic potency when combined with PTP inhibitors, reversing drug resistance that was responsible for clinical failures during cancer therapy.

AREAS COVERED

This review aimed to elaborate recent insights that supported the involvement of PTP-mediated pathways in the development of resistance to targeted therapy and immune-checkpoint therapy.

EXPERT OPINION

This review proposed the notion of PTP inhibition in anticancer combination therapy as a potential strategy in clinic to achieve long-term tumor regression. Ongoing clinical trials are currently underway to assess the safety and efficacy of combination therapy in advanced-stage tumors.

TREM2 mediates MHCII-associated CD4+ T-cell response against gliomas

BACKGROUND

Myeloid cells comprise up to 50% of the total tumor mass in glioblastoma (GBM) and have been implicated in promoting tumor progression and immunosuppression. Modulating the response of myeloid cells to the tumor has emerged as a promising new approach for cancer treatment. In this regard, we focus on the Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), which has recently emerged as a novel immune modulator in peripheral tumors.

METHODS

We studied the TREM2 expression profile in various patient tumor samples and conducted single-cell transcriptomic analysis in both GBM patients and the GL261 mouse glioma model. We utilized multiple mouse glioma models and employed state-of-the-art techniques such as invivo 2-photon imaging, spectrum flow cytometry, and in vitro co-culture assays to study TREM2 function in myeloid cell-mediated phagocytosis of tumor cells, antigen presentation, and response of CD4+ T cells within the tumor hemispheres.

RESULTS

Our research revealed significantly elevated levels of TREM2 expression in brain tumors compared to other types of tumors in patients. TREM2 was predominantly localized in tumor-associated myeloid cells and was highly expressed in nearly all microglia, as well as various subtypes of macrophages. Surprisingly, in preclinical glioma models, TREM2 deficiency did not confer a beneficial effect; instead, it accelerated glioma progression. Through detailed investigations, we determined that TREM2 deficiency impaired the ability of tumor-myeloid cells to phagocytose tumor cells and led to reduced expression of MHCII. This deficiency further significantly decreased the presence of CD4+ T cells within the tumor hemispheres.

CONCLUSIONS

Our study unveiled a previously unrecognized protective role of tumor-myeloid TREM2. Specifically, we found that TREM2 enhances the phagocytosis of tumor cells and promotes an immune response by facilitating MHCII-associated CD4+ T-cell responses against gliomas.

Protein tyrosine phosphatases as emerging targets for cancer immunotherapy

Contemporary strategies in cancer immunotherapy, despite remarkable success, remain constrained by inherent limitations such as suboptimal patient responses, the emergence of drug resistance, and the manifestation of pronounced adverse effects. Consequently, the need for alternative strategies for immunotherapy becomes clear. Protein tyrosine phosphatases (PTPs) wield a pivotal regulatory influence over an array of essential cellular processes. Substantial research has underscored the potential in targeting PTPs to modulate the immune responses and/or regulate antigen presentation, thereby presenting a novel paradigm for cancer immunotherapy. In this review, we focus on recent advances in genetic and biological validation of several PTPs as emerging targets for immunotherapy. We also highlight recent development of small molecule inhibitors and degraders targeting these PTPs as novel cancer immunotherapeutic agents.

A small molecule inhibitor of PTP1B and PTPN2 enhances T cell anti-tumor immunity

The inhibition of protein tyrosine phosphatases 1B (PTP1B) and N2 (PTPN2) has emerged as an exciting approach for bolstering T cell anti-tumor immunity. ABBV-CLS-484 is a PTP1B/PTPN2 inhibitor in clinical trials for solid tumors. Here we have explored the therapeutic potential of a related small-molecule-inhibitor, Compound-182. We demonstrate that Compound-182 is a highly potent and selective active site competitive inhibitor of PTP1B and PTPN2 that enhances T cell recruitment and activation and represses the growth of tumors in mice, without promoting overt immune-related toxicities. The enhanced anti-tumor immunity in immunogenic tumors can be ascribed to the inhibition of PTP1B/PTPN2 in T cells, whereas in cold tumors, Compound-182 elicited direct effects on both tumor cells and T cells. Importantly, treatment with Compound-182 rendered otherwise resistant tumors sensitive to α-PD-1 therapy. Our findings establish the potential for small molecule inhibitors of PTP1B and PTPN2 to enhance anti-tumor immunity and combat cancer.

A small molecule inhibitor of PTP1B and PTPN2 enhances T cell anti-tumor immunity

The inhibition of protein tyrosine phosphatases (PTPs), such as PTP1B and PTPN2 that function as intracellular checkpoints, has emerged as an exciting new approach for bolstering T cell anti-tumor immunity to combat cancer. ABBV-CLS-484 is a dual PTP1B and PTPN2 inhibitor currently in clinical trials for solid tumors. Here we have explored the therapeutic potential of targeting PTP1B and PTPN2 with a related small molecule inhibitor, Compound 182. We demonstrate that Compound 182 is a highly potent and selective active site competitive inhibitor of PTP1B and PTPN2 that enhances antigen-induced T cell activation and expansion ex vivo and represses the growth of syngeneic tumors in C57BL/6 mice without promoting overt immune-related toxicities. Compound 182 repressed the growth of immunogenic MC38 colorectal and AT3-OVA mammary tumors as well as immunologically cold AT3 mammary tumors that are largely devoid of T cells. Treatment with Compound 182 increased both the infiltration and activation of T cells, as well as the recruitment of NK cells and B cells that promote anti-tumor immunity. The enhanced anti-tumor immunity in immunogenic AT3-OVA tumors could be ascribed largely to the inhibition of PTP1B/PTPN2 in T cells, whereas in cold AT3 tumors, Compound 182 elicited both direct effects on tumor cells and T cells to facilitate T cell recruitment and thereon activation. Importantly, treatment with Compound 182 rendered otherwise resistant AT3 tumors sensitive to anti-PD1 therapy. Our findings establish the potential for small molecule active site inhibitors of PTP1B and PTPN2 to enhance anti-tumor immunity and combat cancer.

IL8 derived from macrophages inhibits CD8+ T-cell function by downregulating TIM3 expression through IL8-CXCR2 axis in patients with advanced colorectal cancer

BACKGROUND

T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) is a vital immune checkpoint that regulates the immune response. However, the specific role of TIM3 in patients with colorectal cancer (CRC) have rarely been studied. In this study, we investigated the effect of TIM3 on CD8⁺ T cells in CRC and explored the mechanism of TIM3 regulation in tumor microenvironment (TME).

METHODS

Peripheral blood and tumor tissues of patients with CRC were collected to evaluate TIM3 expression using flow cytometry. Cytokines in the serum of healthy donors and patients with early- and advanced-stage CRC were screened using a multiplex assay. The effects of interleukin-8 (IL8) on TIM3 expression on CD8⁺ T cells were analyzed using cell incubation experiments in vitro. The correlation between TIM3 or IL8 and prognosis was verified using bioinformatics analysis.

RESULTS

TIM3 expression on CD8⁺ T cells was obviously reduced in patients with advanced-stage CRC, whereas a lower TIM3 expression level was associated with poorer prognosis. Macrophage-derived IL8, which could inhibit TIM3 expression on CD8⁺ T cells, was significantly increased in the serum of patients with advanced CRC. In addition, the function and proliferation of CD8⁺ and TIM3⁺CD8⁺ T cells were inhibited by IL8, which was partly depending on TIM3 expression. The inhibitory effects of IL8 were reversed by anti-IL8 and anti-CXCR2 antibodies.

CONCLUSIONS

In summary, macrophages-derived IL8 suppresses TIM3 expression on CD8⁺ T cells through CXCR2. Targeting the IL8/CXCR2 axis may be an effective strategy for treating patients with advanced CRC.

TREM2 mediates MHCII-associated CD4+ T cell response against gliomas

Triggering receptor expressed on myeloid cells 2 (TREM2) was recently highlighted as a novel immune suppressive marker in peripheral tumors. The aim of this study was to characterize TREM2 expression in gliomas and investigate its contribution in glioma progression by using Trem2-/- mouse line. Our results showed that higher TREM2 expression was correlated with poor prognosis in glioma patients. Unexpectedly, TREM2 deficiency did not have a beneficial effect in a pre-clinical model of glioma. The increased TREM2 expression in glioma was likely due to increased myeloid cell infiltration, as evidenced by our single-cell analysis showing that almost all microglia and macrophages in gliomas were TREM2+. Furthermore, we found that deficiency of TREM2 impaired tumor-myeloid phagocytosis and MHCII presentation, and significantly reduced CD4+ T cells in tumor hemispheres. Our results revealed a previously unrecognized protective role of tumor-myeloid TREM2 in promoting MHCII-associated CD4+ T cell response against gliomas.

Targeting protein phosphatases in cancer immunotherapy and autoimmune disorders

Protein phosphatases act as key regulators of multiple important cellular processes and are attractive therapeutic targets for various diseases. Although extensive effort has been dedicated to phosphatase-targeted drug discovery, early expeditions for competitive phosphatase inhibitors were plagued by druggability issues, leading to the stigmatization of phosphatases as difficult targets. Despite challenges, persistent efforts have led to the identification of several drug-like, non-competitive modulators of some of these enzymes - including SH2 domain-containing protein tyrosine phosphatase 2, protein tyrosine phosphatase 1B, vascular endothelial protein tyrosine phosphatase and protein phosphatase 1 - reigniting interest in therapeutic targeting of phosphatases. Here, we discuss recent progress in phosphatase drug discovery, with emphasis on the development of selective modulators that exhibit biological activity. The roles and regulation of protein phosphatases in immune cells and their potential as powerful targets for immuno-oncology and autoimmunity indications are assessed.

PTPN2 in the Immunity and Tumor Immunotherapy: A Concise Review

PTPN2 (protein tyrosine phosphatase non-receptor 2), also called TCPTP (T cell protein tyrosine phosphatase), is a member of the PTP family signaling proteins. Phosphotyrosine-based signaling of this non-transmembrane protein is essential for regulating cell growth, development, differentiation, survival, and migration. In particular, PTPN2 received researchers’ attention when Manguso et al. identified PTPN2 as a cancer immunotherapy target using in vivo CRISPR library screening. In this review, we attempt to summarize the important functions of PTPN2 in terms of its structural and functional properties, inflammatory reactions, immunomodulatory properties, and tumor immunity. PTPN2 exerts synergistic anti-inflammatory effects in various inflammatory cells and regulates the developmental differentiation of immune cells. The diversity of PTPN2 effects in different types of tumors makes it a potential target for tumor immunotherapy.

Critical roles of PTPN family members regulated by non-coding RNAs in tumorigenesis and immunotherapy

Since tyrosine phosphorylation is reversible and dynamic in vivo, the phosphorylation state of proteins is controlled by the opposing roles of protein tyrosine kinases (PTKs) and protein tyrosine phosphatase (PTPs), both of which perform critical roles in signal transduction. Of these, intracellular non-receptor PTPs (PTPNs), which belong to the largest class I cysteine PTP family, are essential for the regulation of a variety of biological processes, including but not limited to hematopoiesis, inflammatory response, immune system, and glucose homeostasis. Additionally, a substantial amount of PTPNs have been identified to hold crucial roles in tumorigenesis, progression, metastasis, and drug resistance, and inhibitors of PTPNs have promising applications due to striking efficacy in antitumor therapy. Hence, the aim of this review is to summarize the role played by PTPNs, including PTPN1/PTP1B, PTPN2/TC-PTP, PTPN3/PTP-H1, PTPN4/PTPMEG, PTPN6/SHP-1, PTPN9/PTPMEG2, PTPN11/SHP-2, PTPN12/PTP-PEST, PTPN13/PTPL1, PTPN14/PEZ, PTPN18/PTP-HSCF, PTPN22/LYP, and PTPN23/HD-PTP, in human cancer and immunotherapy and to comprehensively describe the molecular pathways in which they are implicated. Given the specific roles of PTPNs, identifying potential regulators of PTPNs is significant for understanding the mechanisms of antitumor therapy. Consequently, this work also provides a review on the role of non-coding RNAs (ncRNAs) in regulating PTPNs in tumorigenesis and progression, which may help us to find effective therapeutic agents for tumor therapy.

PTPN2, A Key Predictor of Prognosis for Pancreatic Adenocarcinoma, Significantly Regulates Cell Cycles, Apoptosis, and Metastasis

Objective

This study conducted a comprehensive analysis of the members of the PTPN family and emphasized the key role of PTPN2 as a potential therapeutic target and diagnostic biomarker in improving the survival rate of PAAD.

Method

Oncomine was used to analyze the pan-cancer expression of the PTPN gene family. The Cancer Genome Atlas (TCGA) data as well as Genotype-Tissue Expression (GTEx) data were downloaded to analyze the expression and prognosis of PTPNs. The diagnosis of PTPNs was evaluated by the experimental ROC curve. The protein-protein interaction (PPI) network was constructed by combining STRING and Cytoscape. The genes of 50 proteins most closely related to PTPN2 were screened and analyzed by GO and KEGG enrichment. The differentially expressed genes of PTPN2 were found by RNA sequencing, and GSEA enrichment analysis was carried out to find the downstream pathways and targets, which were verified by online tools and experiments. Finally, the relationship between PTPN2 and immune cell infiltration in PAAD, and the relationship with immune score and immune checkpoint were studied.

Result

The expression patterns and the prognostic value of multiple PTPNs in PAAD have been reported through bioinformatic analyzes. Among these members, PTPN2 is the most important prognostic signature that regulates the progression of PAAD by activating JAK-STAT signaling pathway. Comparison of two PAAD cell lines with normal pancreatic epithelial cell lines revealed that PTPN2 expression was up-regulated as a key regulator of PAAD, which was associated with poor prognosis. Knockdown of PTPN2 caused a profound decrease in PAAD cell growth, migration, invasion, and induced PAAD cell cycle and apoptosis. In addition, we conducted a series of enrichment analyses to investigate the PTPN2-binding proteins and the PTPN2 expression-correlated genes. We suggest that STAT1 and EGFR are the key factors to regulate PTPN2, which are involved in the progression of PAAD. Meanwhile, the silencing of PTPN2 induced the repression of STAT1 and EGFR expression.

Conclusion

These findings provide a comprehensive analysis of the PTPN family members, and for PAAD, they also demonstrate that PTPN2 is a diagnostic biomarker and a therapeutic target.

PTPN2 elicits cell autonomous and non-cell autonomous effects on antitumor immunity in triple-negative breast cancer

The tumor-suppressor PTPN2 is diminished in a subset of triple-negative breast cancers (TNBCs). Paradoxically, PTPN2-deficiency in tumors or T cells in mice can facilitate T cell recruitment and/or activation to promote antitumor immunity. Here, we explored the therapeutic potential of targeting PTPN2 in tumor cells and T cells. PTPN2-deficiency in TNBC associated with T cell infiltrates and PD-L1 expression, whereas low PTPN2 associated with improved survival. PTPN2 deletion in murine mammary epithelial cells TNBC models, did not promote tumorigenicity but increased STAT-1-dependent T cell recruitment and PD-L1 expression to repress tumor growth and enhance the efficacy of anti-PD-1. Furthermore, the combined deletion of PTPN2 in tumors and T cells facilitated T cell recruitment and activation and further repressed tumor growth or ablated tumors already predominated by exhausted T cells. Thus, PTPN2-targeting in tumors and/or T cells facilitates T cell recruitment and/or alleviates inhibitory constraints on T cells to combat TNBC.

Synergistic photothermal cancer immunotherapy by Cas9 ribonucleoprotein-based copper sulfide nanotherapeutic platform targeting PTPN2

Photothermal therapy (PTT) is a promising strategy for the treatment of advanced malignant neoplasm. However, the anti-tumor efficacy by PTT alone is insufficient to control tumor growth and metastasis. Here, we report a multifunctional nanotherapeutic system exerting a combined PTT and immunotherapy to synergistically enhance the therapeutic effect on melanoma. In particular, we selected the semiconductor nanomaterial copper sulfide (CuS), which served not only as a near-infrared (NIR) light-triggered photothermal converter for tumor hyperthermia but as a basic carrier to modify Cas9 ribonucleoprotein targeting PTPN2 on its surface. Efficient PTPN2 depletion was observed after the treatment of CuS-RNP@PEI nanoparticles, which caused the accumulation of intratumoral infiltrating CD8 T lymphocytes in tumor-bearing mice and upregulated the expression levels of IFN-ᵧ and TNF-α in tumor tissue, thus sensitizing tumors to immunotherapy. In addition, the effect worked synergistically with tumor ablation and immunogenic cell death (ICD) induced by PTT to amplify anti-tumor efficacy. Taken together, this exogenously controlled method provides a simple and effective treatment option for advanced malignant neoplasm.

Protein tyrosine phosphatome metabolic screen identifies TC-PTP as a positive regulator of cancer cell bioenergetics and mitochondrial dynamics

Metabolic reprogramming occurs in cancer cells and is regulated partly by the opposing actions of tyrosine kinases and tyrosine phosphatases. Several members of the protein tyrosine phosphatase (PTP) superfamily have been linked to cancer as either pro-oncogenic or tumor-suppressive enzymes. In order to investigate which PTPs can modulate the metabolic state of cancer cells, we performed an shRNA screen of PTPs in HCT116 human colorectal cancer cells. Among the 72 PTPs efficiently targeted, 24 were found to regulate mitochondrial respiration, 8 as negative and 16 as positive regulators. Of the latter, we selected TC-PTP (PTPN2) for further characterization since inhibition of this PTP resulted in major functional defects in oxidative metabolism without affecting glycolytic flux. Transmission electron microscopy revealed an increase in the number of damaged mitochondria in TC-PTP-null cells, demonstrating the potential role of this PTP in regulating mitochondrial homeostasis. Downregulation of STAT3 by siRNA-mediated silencing partially rescued the mitochondrial respiration defect observed in TC-PTP-deficient cells, supporting the role of this signaling axis in regulating mitochondrial activity. In addition, mitochondrial stress prevented an increased expression of electron transport chain-related genes in cells with TC-PTP silencing, correlating with decreased ATP production, cellular proliferation, and migration. Our shRNA-based metabolic screen revealed that PTPs can serve as either positive or negative regulators of cancer cell metabolism. Taken together, our findings uncover a new role for TC-PTP as an activator of mitochondrial metabolism, validating this PTP as a key target for cancer therapeutics.