PTN signaling: Components and mechanistic insights in human ovarian cancer

PTPRZ1 dephosphorylates and stabilizes RNF26 to reduce the efficacy of TKIs and PD-1 blockade in ccRCC

Clear cell renal cell carcinoma (ccRCC), the most common subtype of renal cell carcinoma, often exhibits resistance to tyrosine kinase inhibitors (TKIs) when used as monotherapy. However, the integration of PD-1 blockade with TKIs has significantly improved patient survival, making it a leading therapeutic strategy for ccRCC. Despite these advancements, the efficacy of this combined therapy remains suboptimal, necessitating a deeper understanding of the underlying regulatory mechanisms. Through comprehensive analyses, including mass spectrometry, RNA sequencing, lipidomic profiling, immunohistochemical staining, and ex vivo experiments, we explored the interaction between PTPRZ1 and RNF26 and its impact on ccRCC cell behavior. Our results revealed a unique interaction where PTPRZ1 stabilized RNF26 protein expression by dephosphorylating it at the Y432 site. The modulation of RNF26 levels by PTPRZ1 was found to be mediated through the proteasome pathway. Additionally, PTPRZ1, via its interaction with RNF26, activated the TNF/NF-κB signaling pathway, thereby promoting cell proliferation, angiogenesis, and lipid metabolism in ccRCC cells. Importantly, inhibiting PTPRZ1 enhanced the sensitivity of ccRCC to TKIs and PD-1 blockade, an effect that was attenuated when RNF26 was simultaneously knocked down. These findings highlight the critical role of the PTPRZ1-RNF26 axis in ccRCC and suggest that combining PTPRZ1 inhibitors with current TKIs and PD-1 blockade therapies could significantly improve treatment outcomes for ccRCC patients.

scRNA-Seq Analysis Revealed CAFs Regulating HCC Cells via PTN Signaling

Background

Cancer-associated fibroblasts (CAFs) play a pivotal role in shaping the microenvironment of hepatocellular carcinoma (HCC). However, the mechanisms through which CAFs influence the progression of HCC remain incompletely understood.

Methods

Single-cell RNA sequencing datasets (GSE158723 and GSE112271) were retrieved from the Gene Expression Omnibus (GEO) database at the National Center for Biotechnology Information (NCBI) and analyzed using R software. Our analysis suggested that CAFs may promote liver cancer cell development, possibly through the interaction of pleiotrophin (PTN) and syndecan-2 (SDC2). Clinical samples from HCC patients were collected and processed into frozen sections and single-cell suspensions for Masson staining, immunofluorescence staining, and flow cytometry. Additionally, Huh7 liver cancer cells and LO2 normal liver cells were cultured and subjected to immunofluorescence assays using cell slides.

Results

The proportion of CAFs in cancerous tissues was higher than in adjacent non-cancerous tissues, and pleiotrophin (PTN) expression was elevated in cancer tissues compared to adjacent tissues. These findings aligned with the results of the single-cell RNA sequencing (scRNA-seq) analysis. Furthermore, SDC2 expression was significantly upregulated in Huh7 liver cancer cells compared to LO2 normal liver cells.

Discussion

This study suggests that CAFs may contribute to HCC progression via the PTN/SDC2 signaling pathway. Our findings provide deeper insights into the interactions between CAFs and HCC cells within the tumor microenvironment (TME).

Single-cell analysis reveals specific neuronal transition during mouse corticogenesis

Background: Currently, the mechanism(s) underlying corticogenesis is still under characterization. Methods: We curated the most comprehensive single-cell RNA-seq (scRNA-seq) datasets from mouse and human fetal cortexes for data analysis and confirmed the findings with co-immunostaining experiments. Results: By analyzing the developmental trajectories with scRNA-seq datasets in mice, we identified a specific developmental sub-path contributed by a cell-population expressing both deep- and upper-layer neurons (DLNs and ULNs) specific markers, which occurred on E13.5 but was absent in adults. In this cell-population, the percentages of cells expressing DLN and ULN markers decreased and increased, respectively, during the development suggesting direct neuronal transition (namely D-T-U). Whilst genes significantly highly/uniquely expressed in D-T-U cell population were significantly enriched in PTN/MDK signaling pathways related to cell migration. Both findings were further confirmed by co-immunostaining with DLNs, ULNs and D-T-U specific markers across different timepoints. Furthermore, six genes (co-expressed with D-T-U specific markers in mice) showing a potential opposite temporal expression between human and mouse during fetal cortical development were associated with neuronal migration and cognitive functions. In adult prefrontal cortexes (PFC), D-T-U specific genes were expressed in neurons from different layers between humans and mice. Conclusion: Our study characterizes a specific cell population D-T-U showing direct DLNs to ULNs neuronal transition and migration during fetal cortical development in mice. It is potentially associated with the difference of cortical development in humans and mice.

Protein Tyrosine Phosphatase Receptor Zeta 1 as a Potential Target in Cancer Therapy and Diagnosis

Protein tyrosine phosphatase receptor zeta 1 (PTPRZ1) is a type V transmembrane tyrosine phosphatase that is highly expressed during embryonic development, while its expression during adulthood is limited. PTPRZ1 is highly detected in the central nervous system, affecting oligodendrocytes' survival and maturation. In gliomas, PTPRZ1 expression is significantly upregulated and is being studied as a potential cancer driver and as a target for therapy. PTPRZ1 expression is also increased in other cancer types, but there are no data on the potential functional significance of this finding. On the other hand, low PTPRZ1 expression seems to be related to a worse prognosis in some cancer types, suggesting that in some cases, it may act as a tumor-suppressor gene. These discrepancies may be due to our limited understanding of PTPRZ1 signaling and tumor microenvironments. In this review, we present evidence on the role of PTPRZ1 in angiogenesis and cancer and discuss the phenomenal differences among the different types of cancer, depending on the regulation of its tyrosine phosphatase activity or ligand binding. Clarifying the involved signaling pathways will lead to its efficient exploitation as a novel therapeutic target or as a biomarker, and the development of proper therapeutic approaches.

Single-cell RNA sequencing of the Mongolia sheep testis reveals a conserved and divergent transcriptome landscape of mammalian spermatogenesis

Spermatogenesis is a highly coordinated and complex process, and is pivotal for transmitting genetic information between mammalian generations. In this study, we investigated the conservation, differences, and biological functions of homologous genes during spermatogenesis in Mongolia sheep, humans, cynomolgus monkey, and mice using single-cell RNA sequencing technology. We compared X chromosome meiotic inactivation events in Mongolia sheep, humans, cynomolgus monkey, and mice to uncover the concerted activity of X chromosome genes. Subsequently, we focused on the dynamics of gene expression, key biological functions, and signaling pathways at various stages of spermatogenesis in Mongolia sheep and humans. Additionally, the ligand-receptor networks of Mongolia sheep and humans in testicular somatic and germ cells at different developmental stages were mapped to reveal conserved germ cell-soma communication using single-cell resolution. These datasets provided novel information and insights to unravel the molecular regulatory mechanisms of Mongolia sheep spermatogenesis and highlight conservation in gene expression during spermatogenesis between Mongolia sheep and humans, providing a foundation for the establishment of a large mammalian disease model of male infertility.

Assessing the Angiogenic Efficacy of Pleiotrophin Released from Injectable Heparin-Alginate Gels

With this work, we design alginate-based hydrogels for therapeutically directing revascularization and repair processes in vivo. We immobilize pleiotrophin (PTN) in injectable hydrogel formulations as the target factor to stimulate proangiogenic responses in endothelial cells. The optimized heparin-alginate/chitosan hydrogels, produced by internal crosslinking with calcium carbonate, show good biocompatibility and injectability and allow controlling the release of immobilized proteins in the subcutaneous tissue over a period of 7 days. In vitro assays, performed with translational human induced pluripotent stem cell-derived endothelial cells, and the in vivo Matrigel plug assay are conducted to demonstrate the angiogenic effects of PTN on endothelial cells. Our results indicate that PTN stimulates endothelial cell morphogenesis in vitro and the migration of endothelial cells and macrophages as soon as 4 days after injections of the developed hydrogels, promoting the formation of structures similar to the healthy granulation tissue, which is an indicator of healing in ischemic wounds. These studies provide the rationale for further investigating this novel therapeutic for pursuing increased vascular density for efficient regeneration of ischemic tissues, by leveraging the host endothelial cell population to initiate angiogenic and reparative processes in vivo. Impact statement Localized, sustained, and controlled delivery of angiogenic factors is crucial for enabling the formation of novel vascular networks in ischemic tissues. This study describes the development of an injectable heparin-alginate/collagen hydrogel for controlling the in vivo release and bioactivity of pleiotrophin (PTN), a heparin-binding factor with significant angiogenic activity. We demonstrate that PTN promotes angiogenesis in an in vitro model of hypoxia and in preclinical subcutaneous models. These results advance our understanding of PTN function in guiding therapeutic angiogenesis and are critical to inform the development of novel translational strategies for ischemic tissue repair and regeneration.

Pleiotrophin: Activity and mechanism

Pleiotrophin (PTN) is a potent mitogenic cytokine with a high affinity for the polysaccharide glycosaminoglycan (GAG). Although it is most strongly associated with neural development during embryogenesis and the neonatal period, its expression has also been linked to a plethora of other physiological events including cancer metastasis, angiogenesis, bone development, and inflammation. A considerable amount of research has been carried out to understand the mechanisms by which PTN regulates these events. In particular, PTN has now been shown to bind a diverse collection of receptors including many GAG-containing proteoglycans. These interactions lead to the activation of many intracellular kinases and, ultimately, activation and transformation of cells. Structural studies of PTN in complex with both GAG and domains from its non-proteoglycan receptors reveal a binding mechanism that relies on electrostatic interactions and points to PTN-induced receptor oligomerization as one of the possible ways PTN uses to control cellular functions.

Protein tyrosine phosphatases: promising targets in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. It is the fourth leading cause of cancer-related death and is associated with a very poor prognosis. KRAS driver mutations occur in approximately 95% of PDAC cases and cause the activation of several signaling pathways such as mitogen-activated protein kinase (MAPK) pathways. Regulation of these signaling pathways is orchestrated by feedback loops mediated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), leading to activation or inhibition of its downstream targets. The human PTPome comprises 125 members, and these proteins are classified into three distinct families according to their structure. Since PTP activity description, it has become clear that they have both inhibitory and stimulatory effects on cancer-associated signaling processes and that deregulation of PTP function is closely associated with tumorigenesis. Several PTPs have displayed either tumor suppressor or oncogenic characteristics during the development and progression of PDAC. In this sense, PTPs have been presented as promising candidates for the treatment of human pancreatic cancer, and many PTP inhibitors have been developed since these proteins were first associated with cancer. Nevertheless, some challenges persist regarding the development of effective and safe methods to target these molecules and deliver these drugs. In this review, we discuss the role of PTPs in tumorigenesis as tumor suppressor and oncogenic proteins. We have focused on the differential expression of these proteins in PDAC, as well as their clinical implications and possible targeting for pharmacological inhibition in cancer therapy.

The polypeptide GALNT6 Displays Redundant Functions upon Suppression of its Closest Homolog GALNT3 in Mediating Aberrant O-Glycosylation, Associated with Ovarian Cancer Progression

Epithelial ovarian cancer (EOC) represents the most lethal gynecologic malignancy; a better understanding of the molecular mechanisms associated with EOC etiology could substantially improve EOC management. Aberrant O-glycosylation in cancer is attributed to alteration of N-acetylgalactosaminyltransferases (GalNAc-Ts). Reports suggest a genetic and functional redundancy between GalNAc-Ts, and our previous data are indicative of an induction of GALNT6 expression upon GALNT3 suppression in EOC cells. We performed single GALNT3 and double GALNT3/T6 suppression in EOC cells, using a combination of the CRISPR-Cas9 system and shRNA-mediated gene silencing. The effect of single GALNT3 and double GALNT3/T6 inhibition was monitored both in vitro (on EOC cells roliferation, migration, and invasion) and in vivo (on tumor formation and survival of experimental animals). We confirmed that GALNT3 gene ablation leads to strong and rather compensatory GALNT6 upregulation in EOC cells. Moreover, double GALNT3/T6 suppression was significantly associated with stronger inhibitory effects on EOC cell proliferation, migration, and invasion, and accordingly displayed a significant increase in animal survival rates compared with GALNT3-ablated and control (Ctrl) EOC cells. Our data suggest a possible functional redundancy of GalNAc-Ts (GALNT3 and T6) in EOC, with the perspective of using both these enzymes as novel EOC biomarkers and/or therapeutic targets.

The Expression, Functions, Interactions and Prognostic Values of PTPRZ1: A Review and Bioinformatic Analysis

Available studies demonstrate that receptor-type tyrosine-protein phosphatase zeta (PTPRZ1) is expressed in different tumor tissues, and functions in cell proliferation, cell adhesion and migration, epithelial-to-mesenchymal transition, cancer stem cells and treatment resistance by interacting with or binding to several molecules. These included pleiotrophin (PTN), midkine, interleukin-34, β-catenin, VEGF, NF-κB, HIF-2, PSD-95, MAGI-3, contactin and ErbB4. PTPRZ1 was involved in survival signaling and could predict the prognosis of several tumors. This review discusses: the current knowledge about PTPRZ1, its expression, co-receptors, ligands, functions, signaling pathway, prognostic values and therapeutic agents that target PTPRZ1.

Hmgb3 Induces the Differentiation of Uterine Stromal Cells Through Targeting Ptn

Uterine decidualization is crucial for placenta formation and pregnancy maintenance. Although previous studies have reported that high mobility group box 3 (Hmgb3) is involved in the regulation of cellular proliferation and differentiation, little is known regarding its physiological role in uterine decidualization. Here, in situ hybridization result exhibited a dynamic expression pattern of Hmgb3 messenger RNA (mRNA) during early gestation, and it was mainly localized to the decidua on days 6 to 8 of gestation. Consistently, elevated Hmgb3 expression was noted in the decidualizing stromal cells after intraluminal oil infusion. In uterine luminal epithelium of ovariectomized mice, estrogen induced the accumulation of Hmgb3 mRNA, which was dependent on the existence of implanting blastocyst. Simultaneously, Hmgb3 could stimulate the proliferation of uterine stromal cells and promote the expression of Prl8a2, a reliable marker for stromal cell differentiation. Further analysis evidenced that Hmgb3 might modulate the expression of pleiotropin (Ptn) in uterine stromal cells. Moreover, silencing of Ptn could impede the upregulation of Prl8a2 elicited by Hmgb3 overexpression, while overexpression of Ptn reversed the repressive effects of Hmgb3 siRNA on Prl8a2 expression. Collectively, Hmgb3 may direct uterine decidualization through targeting Ptn.

Stepping out of the shadows: Oncogenic and tumor-promoting protein tyrosine phosphatases

Protein tyrosine phosphorylation is critical for proper function of cells and organisms. Phosphorylation is regulated by the concerted but generically opposing activities of tyrosine kinases (PTKs) and tyrosine phosphatases (PTPs), which ensure its proper regulation, reversibility, and ability to respond to changing physiological situations. Historically, PTKs have been associated mainly with oncogenic and pro-tumorigenic activities, leading to the generalization that protein dephosphorylation is anti-oncogenic and hence that PTPs are tumor-suppressors. In many cases PTPs do suppress tumorigenesis. However, a growing body of evidence indicates that PTPs act as dominant oncogenes and drive cell transformation in a number of contexts, while in others PTPs support transformation that is driven by other oncogenes. This review summarizes the known transforming and tumor-promoting activities of the classical, tyrosine specific PTPs and highlights their potential as drug targets for cancer therapy.

Midkine and pleiotrophin concentrations in needle biopsies of breast and lung masses

BACKGROUND/OBJECTIVE

Midkine (MDK) and pleiotrophin (PTN) are two closely related heparin-binding growth factors which are overexpressed in a wide variety of human cancers. We hypothesized that the concentrations of these factors in washout of biopsy needles would be higher in breast and lung cancer than in benign lesions.

METHODS

Seventy subjects underwent pre-operative core needle biopsies of 78 breast masses (16 malignancies). In 11 subjects, fine needle aspiration was performed ex vivo on 7 non-small cell lung cancers and 11 normal lung specimens within surgically excised lung tissue. The biopsy needle was washed with buffer for immunoassay.

RESULTS

The MDK/DNA and the PTN/DNA ratio in most of the malignant breast masses were similar to the ratios in benign masses except one lobular carcinoma in situ (24-fold higher PTN/DNA ratio than the average benign mass). The MDK/DNA and PTN/DNA ratio were similar in most malignant and normal lung tissue except one squamous cell carcinoma (38-fold higher MDK/DNA ratio than the average of normal lung tissue).

CONCLUSIONS

Both MDK and PTN are readily measurable in washout of needle biopsy samples from breast and lung masses and levels are highly elevated only in a specific subset of these malignancies.

Aurora A kinase regulates non-homologous end-joining and poly(ADP-ribose) polymerase function in ovarian carcinoma cells

Ovarian cancer is usually diagnosed at late stages when cancer has spread beyond the ovary and patients ultimately succumb to the development of drug-resistant disease. There is an urgent and unmet need to develop therapeutic strategies that effectively treat ovarian cancer and this requires a better understanding of signaling pathways important for ovarian cancer progression. Aurora A kinase (AURKA) plays an important role in ovarian cancer progression by mediating mitosis and chromosomal instability. In the current study, we investigated the role of AURKA in regulating the DNA damage response and DNA repair in ovarian carcinoma cells. We discovered that AURKA modulated the expression and activity of PARP, a crucial mediator of DNA repair that is a target of therapeutic interest for the treatment of ovarian and other cancers. Further, specific inhibition of AURKA activity with the small molecule inhibitor, alisertib, stimulated the non-homologous end-joining (NHEJ) repair pathway by elevating DNA-PKcs activity, a catalytic subunit required for double-strand break (DSB) repair, as well as decreased the expression of PARP and BRCA1/2, which are required for high-fidelity homologous recombination-based DNA repair. Further, AURKA inhibition stimulates error-prone NHEJ repair of DNA double-strand breaks with incompatible ends. Consistent with in vitro findings, alisertib treatment increased phosphorylated DNA-PKcs(pDNA-PKcsT2609) and decreased PARP levels in vivo. Collectively, these results reveal new non-mitotic functions for AURKA in the regulation of DNA repair, which may inform of new therapeutic targets and strategies for treating ovarian cancer.

Therapeutic silence of pleiotrophin by targeted delivery of siRNA and its effect on the inhibition of tumor growth and metastasis

Pleiotrophin (PTN) is a secreted cytokine that is expressed in various cancer cell lines and human tumor such as colon cancer, lung cancer, gastric cancer and melanoma. It plays significant roles in angiogenesis, metastasis, differentiation and cell growth. The expression of PTN in the adult is limited to the hippocampus in an activity-dependent manner, making it a very attractive target for cancer therapy. RNA interference (RNAi) offers great potential as a new powerful therapeutic strategy based on its highly specific and efficient silencing of a target gene. However, efficient delivery of small interfering RNA (siRNA) in vivo remains a significant hurdle for its successful therapeutic application. In this study, we first identified, on a cell-based experiment, applying a 1:1 mixture of two PTN specific siRNA engenders a higher silencing efficiency on both mRNA and protein level than using any of them discretely at the same dose. As a consequence, slower melanoma cells growth was also observed for using two specific siRNA combinatorially. To establish a robust way for siRNA delivery in vivo and further investigate how silence of PTN affects tumor growth, we tested three different methods to deliver siRNA in vivo: first non-targeted in-vivo delivery of siRNA via jetPEI; second lung targeted delivery of siRNA via microbubble coated jetPEI; third tumor cell targeted delivery of siRNA via transferrin-polyethylenimine (Tf-PEI). As a result, we found that all three in-vivo siRNAs delivery methods led to an evident inhibition of melanoma growth in non-immune deficiency C57BL/6 mice without a measureable change of ALT and AST activities. Both targeted delivery methods showed more significant curative effect than jetPEI. The lung targeted delivery by microbubble coated jetPEI revealed a comparable therapeutic effect with Tf-PEI, indicating its potential application for target delivery of siRNA in vivo.

Correlation of Collagen Triple Helix Repeat Containing 1 Overexpression With Lymph Node and Peritoneal Metastasis in Epithelial Ovarian Cancer

OBJECTIVE

This study aimed to reveal whether collagen triple helix repeat containing 1 (CTHRC1) was a predictor of peritoneal and lymph node metastases in epithelial ovarian cancer, which had not been researched by others previously.

MATERIALS AND METHODS

Western blot analysis showed that dramatic overexpression of CTHRC1 could be seen in most metastatic tissues. Univariate and multivariate logistic regression analyses demonstrated that overexpression of CTHRC1 was linked with peritoneal dissemination and lymph node metastasis in epithelial ovarian cancer.

RESULTS

The negative and sensitivity-predictive values of CTHRC1 staining were excellent for both lymph node and peritoneal metastases. The odds ratio of high versus low staining for peritoneal dissemination was 2.250 (95% confidence interval, 1.126-4.496), and that for lymph node metastasis was 13.102 (95% confidence interval, 6.036-28.439).

CONCLUSIONS

Collagen triple helix repeat containing 1 may potentially be used as a predictive marker of clinical progression in ovarian cancer either alone or in combination with other markers.

High expression of CTHRC1 promotes EMT of epithelial ovarian cancer (EOC) and is associated with poor prognosis

Collagen triple helix repeat-containing 1 (CTHRC1) is aberrantly overexpressed in multiple malignant tumors. However, the expression characteristics and function of CTHRC1 in epithelial ovarian cancer (EOC) remain unclear. We found that CTHRC1 expression was up-regulated in the paraffin-embedded EOC tissues compared to borderline or benign tumor tissues. CTHRC1 expression was positively correlated with tumor size (p = 0.008), menopause (p = 0.037), clinical stage (p = 0.002) and lymph node metastasis (p < 0.001) and was also an important prognostic factor for the overall survival of EOC patients, as revealed by Kaplan-Meier analysis. CTHRC1 increased the invasive capabilities of EOC cells in vitro by activating the Wnt/β-catenin signaling pathway. We showed that ectopic transfection of CTHRC1 in EOC cells up-regulated the expression of EMT markers such as N-cadherin and vimentin, and EMT-associated transcriptional factor Snail. Knockdown of CTHRC1 expression in EOC cells resulted in down-regulation of N-cadherin, vimentin, Snail and translocation of β-catenin. Collectively, CTHRC1 may promote EOC metastasis through the induction of EMT process and serve as a potential biomarker for prognosis as well as a target for therapy.

Increased Pleiotrophin Concentrations in Papillary Thyroid Cancer

Background

Thyroid nodules are common, and approximately 5% of these nodules are malignant. Pleiotrophin (PTN) is a heparin-binding growth factor which is overexpressed in many cancers. The expression of PTN in papillary thyroid cancer (PTC) is unknown.

Method and Findings

74 subjects (age 47 ± 12 y, 15 males) who had thyroidectomy with a histological diagnosis: 79 benign nodules and 23 PTCs (10 classic, 6 tall cell, 6 follicular variant and 1 undetermined). Fine-needle aspiration (FNA) samples were obtained ex vivo from surgically excised tissue and assayed for PTN and thyroglobulin (Tg). Immunohistochemistry (IHC) was performed on tissue sections. In FNA samples, PTN concentration normalized to Tg was significantly higher in PTC than in benign nodules (16 ± 6 vs 0.3 ± 0.1 ng/mg, p < 0.001). In follicular variant of PTC (n = 6), the PTN/Tg ratio was also higher than in benign nodules (1.3 ± 0.6 vs 0.3 ± 0.1 ng/mg, P < 0.001, respectively). IHC showed cytoplasmic localization of PTN in PTC cells.

Conclusion

In ex vivo FNA samples, the PTN to thyroglobulin ratio was higher in PTCs, including follicular variant PTC, than in benign thyroid nodules. The findings raise the possibility that measurement of the PTN to Tg ratio may provide useful diagnostic and/or prognostic information in the evaluation of thyroid nodules.