MSP-RON Signaling Is Activated in the Transition From Pancreatic Intraepithelial Neoplasia (PanIN) to Pancreatic Ductal Adenocarcinoma (PDAC)

Preliminary Observations of a Substrate-Based Radiotracer Biosensor for In Vivo Positron Emission Tomography Imaging of Tumor Transmembrane Protease ST14

Imaging protease proteolysis with positron emission tomography (PET) has not been well documented in the literature, primarily due to the absence of suitable radiotracers. This study aims to develop a substrate-based radiotracer biosensor for ST14 protease to facilitate direct in vivo PET imaging of proteolysis. The design of the substrate-based radiotracer RQARK-DOTA-68Ga is characterized by the inclusion of an ST14 substrate RQAR moiety and a Lys-DOTA-68Ga moiety, linked via an ST14 cleavage site. The enzymatic cleavage of this radiotracer by ST14 protease was characterized in vitro, and the proteolysis of ST14 was further confirmed through in vivo PET imaging in tumors expressing ST14. RQARK-DOTA-68Ga was specifically cleaved by ST14 protease to yield Lys-DOTA-68Ga and RQAR moieties, whereas the d-isomer, rqark-DOTA-68Ga, was not susceptible to cleavage by ST14 protease. In vivo PET imaging demonstrated high tumor uptake of radioactive signal postinjection RQARK-DOTA-68Ga in ST14-expressing AsPC-1 xenografts, with optimal accumulation observed 1 h postinjection. In contrast, the d-isomer radiotracer, rqark-DOTA-68Ga, exhibited negligible tumor uptake, indicating a distinct preference for the substrate-based radiotracer in regions of ST14-mediated proteolysis. Radio-HPLC analysis following extraction from AsPC-1 tumors injected with RQARK-DOTA-68Ga identified a radioactive peak corresponding to Lys-DOTA-68Ga, confirming enzymatic cleavage and the generation of the anticipated radioactive product in the tumor tissue. Preliminary results indicate that a novel strategy for noninvasive in vivo positron emission tomography imaging of the transmembrane protease ST14 in tumors has been introduced through the development and application of a substrate-based radiotracer biosensor. The radiotracer RQARK-DOTA-68Ga, capable of producing imaging signals through structural changes triggered by substrate cleavage, has proven its ST14-targeting potency in both in vitro enzymatic assays and in vivo PET imaging.

First-generation high-affinity ST14 radiopharmaceutical: Design, synthesis, and preclinical PET imaging evaluation for pancreatic cancer detection

The non-specificity of 18F-FDG, coupled with high false-positive rates in pancreatitis, underscores an unmet clinical need for using specific positron emission tomography (PET) radiopharmaceuticals in noninvasive pancreatic cancer detection. ST14, a trypsin-like protease and a member of the type II transmembrane serine protease family, is overexpressed in various solid malignancies, including pancreatic cancer. This study aimed to develop a 68Ga-labeled PET radiopharmaceutical targeting ST14 for pancreatic cancer detection. A precursor ST14-06 was designed, and molecular docking was employed to preliminarily predict the binding mode. ST14-06 emerged as the preferred precursor with experimental inhibition assays confirming its high affinity for ST14 (IC50 = 1.06 ± 0.08 nM). 68Ga-ST14-06 was successfully synthesized with high radiochemical purity (RCP, >95 %) and molar activity (25-30 GBq/μmol) and was stable in saline and serum. In vitro studies demonstrated specific binding of the tracer to ST14-positive AsPC-1 cells compared to the blocking group (11.45 ± 0.12 % vs. 2.48 ± 0.34 %, P < 0.01). PET/CT imaging in AsPC-1 tumor-bearing mice confirmed ST14-specific uptake, which was reduced by co-administration of an excess blocking agent. Biodistribution studies revealed higher distribution in AsPC-1 tumors (0.99 ± 0.08 %ID/g) than in PANC-1 tumors (0.32 ± 0.02 %ID/g) and the blocking group (0.32 ± 0.04 %ID/g) at 1 h post-injection. Immunohistochemistry results showed that ST14 was highly positive in AsPC-1 tumors, but was negative in PANC-1 tumors. These preliminary findings suggest that 68Ga-ST14-06 has potential as a first-generation PET radiopharmaceutical for ST14-specific imaging, offering a promising tool for pancreatic cancer detection.

Combined PET Radiotracer Approach Reveals Insights into Stromal Cell-Induced Metabolic Changes in Pancreatic Cancer In Vitro and In Vivo

Background/Objective Pancreatic stellate cells (PSCs) in pancreatic adenocarcinoma (PDAC) are producing extracellular matrix, which promotes the formation of a dense fibrotic microenvironment. This makes PDAC a highly heterogeneous tumor-stroma-driven entity, associated with reduced perfusion, limited oxygen supply, high interstitial fluid pressure, and limited bioavailability of therapeutic agents. Methods In this study, spheroid and tumor xenograft models of human PSCs and PanC-1 cells were characterized radiopharmacologically using a combined positron emission tomography (PET) radiotracer approach. [18F]FDG, [18F]FMISO, and [18F]FAPI-74 were employed to monitor metabolic activity, hypoxic metabolic state, and functional expression of fibroblast activation protein alpha (FAPα), a marker of activated PSCs. Results In vitro, PanC-1 and multi-cellular tumor spheroids demonstrated comparable glucose uptake and hypoxia, whereas FAPα expression was significantly higher in PSC spheroids. In vivo, glucose uptake as well as the transition to hypoxia were comparable in PanC-1 and multi-cellular xenograft models. In mice injected with PSCs, FAPα expression decreased over a period of four weeks post-injection, which was attributed to the successive death of PSCs. In contrast, FAPα expression increased in both PanC-1 and multi-cellular xenograft models over time due to invasion of mouse fibroblasts. Conclusion The presented models are suitable for subsequently characterizing stromal cell-induced metabolic changes in tumors using noninvasive molecular imaging techniques.

Matriptase-dependent epidermal pre-neoplasm in zebrafish embryos caused by a combination of hypotonic stress and epithelial polarity defects

Aberrantly up-regulated activity of the type II transmembrane protease Matriptase-1 has been associated with the development and progression of a range of epithelial-derived carcinomas, and a variety of signaling pathways can mediate Matriptase-dependent tumorigenic events. During mammalian carcinogenesis, gain of Matriptase activity often results from imbalanced ratios between Matriptase and its cognate transmembrane inhibitor Hai1. Similarly, in zebrafish, unrestrained Matriptase activity due to loss of hai1a results in epidermal pre-neoplasms already during embryogenesis. Here, based on our former findings of a similar tumor-suppressive role for the Na+/K+-pump beta subunit ATP1b1a, we identify epithelial polarity defects and systemic hypotonic stress as another mode of aberrant Matriptase activation in the embryonic zebrafish epidermis in vivo. In this case, however, a different oncogenic pathway is activated which contains PI3K, AKT and NFkB, rather than EGFR and PLD (as in hai1a mutants). Strikingly, epidermal pre-neoplasm is only induced when epithelial polarity defects in keratinocytes (leading to disturbed Matriptase subcellular localization) occur in combination with systemic hypotonic stress (leading to increased proteolytic activity of Matriptase). A similar combinatorial effect of hypotonicity and loss of epithelial polarity was also obtained for the activity levels of Matriptase-1 in human MCF-10A epithelial breast cells. Together, this is in line with the multi-factor concept of carcinogenesis, with the notion that such factors can even branch off from one and the same initiator (here ATP1a1b) and can converge again at the level of one and the same mediator (here Matriptase). In sum, our data point to tonicity and epithelial cell polarity as evolutionarily conserved regulators of Matriptase activity that upon de-regulation can constitute an alternative mode of Matriptase-dependent carcinogenesis in vivo.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

A potential signaling axis between RON kinase receptor and hypoxia-inducible factor-1 alpha in pancreatic cancer

The Cancer Genome Atlas (TCGA) of a pancreatic cancer cohort identified high MST1R (RON tyrosine kinase receptor) expression correlated with poor prognosis in human pancreatic cancer. RON expression is null/minimal in normal pancreas but elevates from pan-in lesions through invasive carcinomas. We report using multiple approaches RON directly regulates HIF-1α, a critical driver of genes involved in cancer cell invasion and metastasis. RON and HIF-1α are highly co-expressed in the 101 human PDAC tumors analyzed and RON expression correlated with HIF-1α expression in a subset of PDAC cell lines. knockdown of RON expression in RON positive cells blocked HIF-1α expression, whereas ectopic RON expression in RON null cells induced HIF-1α expression suggesting the direct regulation of HIF-1α by RON kinase receptor. RON regulates HIF-1α through an unreported transcriptional mechanism involving PI3 kinase-mediated AKT phosphorylation and Sp1-dependent HIF-1α promoter activity leading to increased HIF-1α mRNA expression. RON/HIF-1α modulation altered the invasive behavior of PDAC cells. A small-molecule RON kinase inhibitor decreased RON ligand, MSP-induced HIF-1α expression, and invasion of PDAC cells. Immunohistochemical analysis on RON knockdown orthotopic PDAC tumor xenograft confirmed that RON inhibition significantly blocked HIF-1α expression. RON/HIF-1α co-expression also exists in triple-negative breast cancer cells, a tumor type that also lacks molecular therapeutic targets. This is the first report describing RON/HIF-1α axis in any tumor type and is a potential novel therapeutic target.

Prognostic role of the recepteur d'origine nantais (RON) expression in primary high-grade osteosarcoma

BACKGROUND

Osteosarcoma is a common primary malignant bone tumor susceptible to distant metastasis. The clinical outcome for patients remains poor due to the resistance to chemotherapy and lacking effective therapeutic targets. Recepteur d'origine nantais (RON), a transmembrane protein of the c-MET proto-oncogene family, has been reported to contribute to the malignant progression and bone metastasis in several tumors. The present study aimed to explore the prognostic significance of RON in primary high-grade osteosarcoma.

METHODS

Immunohistochemistry (IHC) and western blotting (WB) were used to investigate the protein expression of RON in 80 surgically resected specimens (50 high-grade osteosarcoma specimens and 30 non-neoplastic bone tissues) and 6 cell lines. The χ² test or independent-sample Student's t-test was used to assess the significance of RON difference between osteosarcoma and non-neoplastic bone tissues. The χ² test and Fisher's exact test were used to analyze the association of RON with the clinicopathological features of osteosarcoma patients. Kaplan-Meier method and Cox proportional hazards model were used to assess the significance of RON for the survival of osteosarcoma patients.

RESULTS

The results of IHC and WB observed significant overexpression of RON in osteosarcoma specimens (P < 0.001) and osteosarcoma cell lines. Moreover, immunohistochemical high expression of RON was associated with a poor response to chemotherapy (P = 0.032) as well as worse progression-free (P = 0.003) and overall (P < 0.001) survival of osteosarcoma patients. Multivariate analysis revealed that high expression of RON was independently associated with reduced progression-free (P = 0.027, HR = 2.31) and overall survival (P = 0.004, HR = 5.06) time of osteosarcoma patients.

CONCLUSIONS

The present study demonstrated that high expression of RON held independent value for unfavorable survival in primary high-grade osteosarcoma. Its potential role as a therapeutic target for osteosarcoma treatment deserves further research.

Mucin Expression and Splicing Determine Novel Subtypes and Patient Mortality in Pancreatic Ductal Adenocarcinoma

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy demonstrating aberrant and progressive expression of mucins. The contribution of individual mucins has been extensively investigated in PDAC; however, comprehensive mucin profiling including splice variants in PDAC tumors has not been reported.

EXPERIMENTAL DESIGN

Using publicly available RNA sequencing (RNA-seq) datasets, we assess the expression of mucin family members and their splice variants (SV) in PDAC tumor samples for the first time. Mucin SVs that are correlated with PDAC patient survival are validated in a cohort of patient tumor samples. Further, we use computational methods to derive novel pancreatic tumor subtypes using mucin expression signatures and their associated activated pathways.

RESULTS

Principal component analysis identified four novel mucin-based PDAC subtypes. Pathway analysis implicated specific biological signatures for each subtype, labeled (i) immune activated, (ii) progressive, (iii) pancreatitis-initiated, and (iv) anti-inflammatory/PanIN-initiated. Assessing mucin SVs, significantly longer survival is observed with higher expression of 4 MUC1 and 1 MUC13 SVs, whereas patients expressing 2 MUC4 and 1 MUC16 SVs had shorter survival. Using a whole-transcriptome correlation, a three-gene panel, including ESRP2, PTK6, and MAGEH1, is designated to assess PDAC tumor sample cellularity by PCR. One MUC4 SV and one MUC13 SV are quantified in a separate PDAC patient cohort, and their effects on survival are experimentally validated.

CONCLUSIONS

Altogether, we demonstrate the unique expression pattern of mucins, four mucin-based PDAC subtypes, and the contribution of MUC1, MUC4, and MUC16 SVs in PDAC patient survival.

RON in hepatobiliary and pancreatic cancers: Pathogenesis and potential therapeutic targets

The receptor protein tyrosine kinase RON belongs to the c-MET proto-oncogene family. Research has shown that RON has a role in cancer pathogenesis, which places RON on the frontline of the development of novel cancer therapeutic strategies. Hepatobiliary and pancreatic (HBP) cancers have a poor prognosis, being reported as having higher rates of cancer-related death. Therefore, to combat these malignant diseases, the mechanism underlying the aberrant expression and signaling of RON in HBP cancer pathogenesis, and the development of RON as a drug target for therapeutic intervention should be investigated. Abnormal RON expression and signaling have been identified in HBP cancers, and also act as tumorigenic determinants for HBP cancer malignant behaviors. In addition, RON is emerging as an important mediator of the clinical prognosis of HBP cancers. Thus, not only is RON significant in HBP cancers, but also RON-targeted therapeutics could be developed to treat these cancers, for example, therapeutic monoclonal antibodies and small-molecule inhibitors. Among them, antibody-drug conjugates have become increasingly popular in current research and their potential as novel anti-cancer biotherapeutics will be determined in future clinical trials.

Recepteur d'origine nantais contributes to the development of endometriosis via promoting epithelial-mesenchymal transition of a endometrial epithelial cells

Endometriosis is a benign, chronic inflammatory disease that commonly occurs in reproductive‐aged women. Epithelial‐mesenchymal transition (EMT) of endometrial epithelial cells plays an important role in the development of endometriosis. Recepteur d'origine nantais (RON), a receptor tyrosine kinase, has been reported to promote EMT and progression in tumours. However, whether and how RON mediates the EMT and endometriosis development is not known. Here, we found that RON activation could improve the migratory and invasive capabilities, change cellular morphologies, and decrease expression of E‐cadherin and increase expression of N‐cadherin in endometrial epithelial cells. Inhibition or knockdown of RON expression suppressed the migration and invasion of endometrial epithelial cells. Our studies also indicated that RON played its part in endometrial epithelial cells through protein kinase B (Akt) and mitogen‐activated protein kinase (MAPK) pathways. Treatment with a RON inhibitor could decrease the number of ectopic lesions in a mouse model of endometriosis and mediate expression of EMT markers in endometriotic lesions. These data suggest that RON contributed to endometriosis development by promoting EMT of endometrial epithelial cells. Therefore, RON may be a new therapeutic target for endometriosis.

Revealing the link between macrophage in microenvironment of osteosarcoma and poor prognosis by utilizing the Integrated analysis

OBJECTIVES

Osteosarcoma (OS) is the most common type of primary malignant bone tumor, The effect of tumor microenvironment components on OS oncogenesis remains unknown.

METHODS

To investigate the function of immune cells in osteosarcoma, we provided a text-based GMT (Gene Matrix Transposed) file in which each line defines one of lm22 with their markers. We used STRING to draw DEG's PPI network and selected hub genes and modules. Then, survival analysis was conducted to hub genes. We identified 10,390 common genes, and identified 218 DEGs based on the combined t-value and Z scores.

RESULTS

The KEGG and GSEA enrichment analysis showed that macrophages are significantly activated in osteosarcoma. PPI network analysis revealed that hub gene CD163 molecule. We found that the expression of CD163 was negatively associated with the OS of osteosarcoma patients. These results suggest that macrophages are a risk factor in patients with osteosarcoma.

CONCLUSIONS

This study has systematically validated results of the studies carried out previously and filled up the gap in the field of OS on large-scaled meta-analysis. In addition, for the hub gene (CD163) and the macrophage cell capable of being used as a novel biomarker in promoting early diagnosis and development of therapeutic approaches.

Ligand-based Discovery of Novel Small Molecule Inhibitors of RON Receptor Tyrosine Kinase

BACKGROUND

RON (Recepteur d'Origine Nantais) receptor tyrosine kinase is a promising target for anti-cancer therapeutics. The aim of this study was to identify new RON inhibitors using virtual screening methods.

METHODS

To this end, a ligand-based virtual screening approach was employed for screening of ZINC database on the homology model of RON receptor. All the selected hits were inspected in terms of drug-likeness, ADME properties, and toxicity profiles. Ligand-based similarity searches along with further filtering criteria led to the identification of two compounds, TKI1 and TKI2 that were evaluated using in vitro cell-based RON inhibition assays.

RESULTS

The results showed that TKI1 and TKI2 could reduce phosphorylation of RON. Both compounds showed inhibitory activity of the downstream mTOR pathway with no apparent effects on other signaling mediators in a dose-dependent manner.

CONCLUSION

These compounds can provide a basis for developing novel anti-RON inhibitors applicable to cancer therapy using medicinal chemistry-oriented optimization strategies.

Single-cell transcriptomics of human islet ontogeny defines the molecular basis of β-cell dedifferentiation in T2D

OBJECTIVE

Dedifferentiation of pancreatic β-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown.

METHODS

We employed single-cell RNAseq to detail the maturation program of α- and β-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals.

RESULTS

Both α- and β-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while β-cells attain a full β-cell specific gene expression program. In islets from T2D donors, both α- and β-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of β-cells displaying suboptimal function observed in T2D islets.

CONCLUSIONS

These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.

Mechanically stressed cancer microenvironment: Role in pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies in the world due to its insensitivity to current therapies and its propensity to metastases from the primary tumor mass. This is largely attributed to its complex microenvironment composed of unique stromal cell populations and extracellular matrix (ECM). The recruitment and activation of these cell populations cause an increase in deposition of ECM components, which highly influences the behavior of malignant cells through disrupted forms of signaling. As PDAC progresses from premalignant lesion to invasive carcinoma, this dynamic landscape shields the mass from immune defenses and cytotoxic intervention. This microenvironment influences an invasive cell phenotype through altered forms of mechanical signaling, capable of enacting biochemical changes within cells through activated mechanotransduction pathways. The effects of altered mechanical cues on malignant cell mechanotransduction have long remained enigmatic, particularly in PDAC, whose microenvironment significantly changes over time. A more complete and thorough understanding of PDAC's physical surroundings (microenvironment), mechanosensing proteins, and mechanical properties may help in identifying novel mechanisms that influence disease progression, and thus, provide new potential therapeutic targets.

Targeting RON receptor tyrosine kinase for treatment of advanced solid cancers: antibody-drug conjugates as lead drug candidates for clinical trials

The recepteur d'origine nantais (RON) receptor tyrosine kinase, belonging to the mesenchymal-to-epithelial transition proto-oncogene family, has been implicated in the pathogenesis of cancers derived from the colon, lung, breast, and pancreas. These findings lay the foundation for targeting RON for cancer treatment. However, development of RON-targeted therapeutics has not gained sufficient attention for the last decade. Although therapeutic monoclonal antibodies (TMABs) targeting RON have been validated in preclinical studies, results from clinical trials have met with limited success. This outcome diminishes pharmaceutical enthusiasm for further development of RON-targeted therapeutics. Recently, antibody-drug conjugates (ADCs) targeting RON have drawn special attention owing to their increased therapeutic activity. The rationale for developing anti-RON ADCs is based on the observation that cancer cells are not sufficiently addicted to RON signaling for survival. Thus, TMAB-mediated inhibition of RON signaling is ineffective for clinical application. In contrast, anti-RON ADCs combine a target-specific antibody with potent cytotoxins for cancer cell killing. This approach not only overcomes the shortcomings in TMAB-targeted therapies but also holds the promise for advancing anti-RON ADCs into clinical trials. In this review, we discuss the latest advancements in the development of anti-RON ADCs for targeted cancer therapy including drug conjugation profile, pharmacokinetic properties, cytotoxic effect in vitro, efficacy in tumor models, and toxicological activities in primates.

RON receptor tyrosine kinase in pancreatic ductal adenocarcinoma: Pathogenic mechanism in malignancy and pharmaceutical target for therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers with poor prognosis and high mortality. Molecular aberrations associated with PDAC pathogenesis and progression have been extensively investigated. Nevertheless, these findings have not been translated into clinical practice. Lack of therapeutics for PDAC treatment is another challenge. Recent application of molecularly targeted and immunoregulatory therapies appears to be disappointing. Thus, discovery of new targets and therapeutics is urgently needed to combat this malignant disease. The RON receptor tyrosine kinase is a tumorigenic determinant in PDAC malignancy, which provides the rationale to target RON for PDAC treatment. In this review, we summarize the latest evidence of RON in PDAC pathogenesis and the development of anti-RON antibody-drug conjugates for potential PDAC therapy. The finding that anti-RON antibody-drug conjugates show efficacy in preclinical animal models highlights the potential of this novel class of anti-cancer biotherapeutics in future clinical trials.