Proteomic profiling of small extracellular vesicles derived from mouse pancreatic cancer and stellate cells: Role in pancreatic cancer

Small extracellular vesicles (sEVs) are cell-derived vesicles evolving as important elements involved in all stages of cancers. sEVs bear unique protein signatures that may serve as biomarkers. Pancreatic cancer (PC) records a very poor survival rate owing to its late diagnosis and several cancer cell-derived proteins have been reported as candidate biomarkers. However, given the pivotal role played by stellate cells (PSCs, which produce the collagenous stroma in PC), it is essential to also assess PSC-sEV cargo in biomarker discovery. Thus, this study aimed to isolate and characterise sEVs from mouse PC cells and PSCs cultured alone or as co-cultures and performed proteomic profiling and pathway analysis. Proteomics confirmed the enrichment of specific markers in the sEVs compared to their cells of origin as well as the proteins that are known to express in each of the culture types. Most importantly, for the first time it was revealed that PSC-sEVs are enriched in proteins (including G6PI, PGAM1, ENO1, ENO3, and LDHA) that mediate pathways related to development of diabetes, such as glucose metabolism and gluconeogenesis revealing a potential role of PSCs in pancreatic cancer-related diabetes (PCRD). PCRD is now considered a harbinger of PC and further research will enable to identify the role of these components in PCRD and may develop as novel candidate biomarkers of PC.

HGF/c-Met pathway inhibition combined with chemotherapy increases cytotoxic T-cell infiltration and inhibits pancreatic tumour growth and metastasis

Pancreatic cancer (PC) is a deadly cancer with a high mortality rate. The unique characteristics of PC, including desmoplasia and immunosuppression, have made it difficult to develop effective treatment strategies. Pancreatic stellate cells (PSCs) play a crucial role in the progression of the disease by interacting with cancer cells. One of the key mediators of PSC - cancer cell interactions is the hepatocyte growth factor (HGF)/c-MET pathway. Using an immunocompetent in vivo model of PC as well as in vitro experiments, this study has shown that a combined approach using HGF/c-MET inhibitors to target stromal-tumour interactions and chemotherapy (gemcitabine) to target cancer cells effectively decreases tumour volume, EMT, and stemness, and importantly, eliminates metastasis. Notably, HGF/c-MET inhibition decreases TGF-β secretion by cancer cells, resulting in an increase in cytotoxic T-cell infiltration, thus contributing to cancer cell death in tumours. HGF/c-MET inhibition + chemotherapy was also found to normalise the gut microbiome and improve gut microbial diversity. These findings provide a strong platform for assessment of this triple therapy (HGF/c-MET inhibition + chemotherapy) approach in the clinical setting.

Metastatic phenotype and immunosuppressive tumour microenvironment in pancreatic ductal adenocarcinoma: Key role of the urokinase plasminogen activator (PLAU)

Background

Previous studies have revealed the role of dysregulated urokinase plasminogen activator (encoded by PLAU) expression and activity in several pathways associated with cancer progression. However, systematic investigation into the association of PLAU expression with factors that modulate PDAC (pancreatic ductal adenocarcinoma) progression is lacking, such as those affecting stromal (pancreatic stellate cell, PSC)-cancer cell interactions, tumour immunity, PDAC subtypes and clinical outcomes from potential PLAU inhibition.

Methods

This study used an integrated bioinformatics approach to identify prognostic markers correlated with PLAU expression using different transcriptomics, proteomics, and clinical data sets. We then determined the association of dysregulated PLAU and correlated signatures with oncogenic pathways, metastatic phenotypes, stroma, immunosuppressive tumour microenvironment (TME) and clinical outcome. Finally, using an in vivo orthotopic model of pancreatic cancer, we confirmed the predicted effect of inhibiting PLAU on tumour growth and metastasis.

Results

Our analyses revealed that PLAU upregulation is not only associated with numerous other prognostic markers but also associated with the activation of various oncogenic signalling pathways, aggressive phenotypes relevant to PDAC growth and metastasis, such as proliferation, epithelial-mesenchymal transition (EMT), stemness, hypoxia, extracellular cell matrix (ECM) degradation, upregulation of stromal signatures, and immune suppression in the tumour microenvironment (TME). Moreover, the upregulation of PLAU was directly connected with signalling pathways known to mediate PSC-cancer cell interactions. Furthermore, PLAU upregulation was associated with the aggressive basal/squamous phenotype of PDAC and significantly reduced overall survival, indicating that this subset of patients may benefit from therapeutic interventions to inhibit PLAU activity. Our studies with a clinically relevant orthotopic pancreatic model showed that even short-term PLAU inhibition is sufficient to significantly halt tumour growth and, importantly, eliminate visible metastasis.

Conclusion

Elevated PLAU correlates with increased aggressive phenotypes, stromal score, and immune suppression in PDAC. PLAU upregulation is also closely associated with the basal subtype type of PDAC; patients with this subtype are at high risk of mortality from the disease and may benefit from therapeutic targeting of PLAU.

HGF/c-Met Inhibition as Adjuvant Therapy Improves Outcomes in an Orthotopic Mouse Model of Pancreatic Cancer

BACKGROUND

Inhibition of hepatocyte growth factor (HGF)/c-MET pathway, a major mediator of pancreatic stellate cell (PSC)-PC cell interactions, retards local and distant cancer progression. This study examines the use of this treatment in preventing PC progression after resection. We further investigate the postulated existence of circulating PSCs (cPSCs) as a mediator of metastatic PC.

METHODS

Two orthotopic PC mouse models, produced by implantation of a mixture of luciferase-tagged human pancreatic cancer cells (AsPC-1), and human PSCs were used. Model 1 mice underwent distal pancreatectomy 3-weeks post-implantation (n = 62). One-week post-resection, mice were randomised to four treatments of 8 weeks: (i) IgG, (ii) gemcitabine (G), (iii) HGF/c-MET inhibition (HiCi) and (iv) HiCi + G. Tumour burden was assessed longitudinally by bioluminescence. Circulating tumour cells and cPSCs were enriched by filtration. Tumours of Model 2 mice progressed for 8 weeks prior to the collection of primary tumour, metastases and blood for single-cell RNA-sequencing (scRNA-seq).

RESULTS

HiCi treatments: (1) reduced both the risk and rate of disease progression after resection; (2) demonstrated an anti-angiogenic effect on immunohistochemistry; (3) reduced cPSC counts. cPSCs were identified using immunocytochemistry (α-smooth muscle actin+, pan-cytokeratin-, CD45-), and by specific PSC markers. scRNA-seq confirmed the existence of cPSCs and identified potential genes associated with development into cPSCs.

CONCLUSIONS

This study is the first to demonstrate the efficacy of adjuvant HGF/c-Met inhibition for PC and provides the first confirmation of the existence of circulating PSCs.

An Orthotopic Resectional Mouse Model of Pancreatic Cancer

There is a lack of satisfactory animal models to study adjuvant and/or neoadjuvant therapy in patients being considered for surgery of pancreatic cancer (PC). To address this deficiency, we describe a mouse model involving orthotopic implantation of PC followed by distal pancreatectomy and splenectomy. The model has been demonstrated to be safe and suitably flexible for the study of various therapeutic approaches in adjuvant and neo adjuvant settings. In this model, a pancreatic tumor is first generated by implanting a mixture of human pancreatic cancer cells (luciferase-tagged AsPC-1) and human cancer associated pancreatic stellate cells into the distal pancreas of Balb/c athymic nude mice. After three weeks, the cancer is resected by re-laparotomy, distal pancreatectomy and splenectomy. In this model, bioluminescence imaging can be used to follow the progress of cancer development and effects of resection/treatments. Following resection, adjuvant therapy can be given. Alternatively, neoadjuvant treatment can be given prior to resection. Representative data from 45 mice are presented. All mice underwent successful distal pancreatectomy/splenectomy with no issues of hemostasis. A macroscopic proximal pancreatic margin greater than 5 mm was achieved in 43 (96%) mice. The technical success rate of pancreatic resection was 100%, with 0% early mortality and morbidity. None of the animals died during the week after resection. In summary, we describe a robust and reproducible technique for a surgical resection model of pancreatic cancer in mice which mimics the clinical scenario. The model may be useful for the testing of both adjuvant and neoadjuvant treatments.

Targeting the HGF/c-MET pathway in advanced pancreatic cancer: a key element of treatment that limits primary tumour growth and eliminates metastasis

Background

Stromal–tumour interactions facilitate pancreatic cancer (PC) progression. The hepatocyte growth factor (HGF)/c-MET pathway is upregulated in PC and mediates the interaction between cancer cells and stromal pancreatic stellate cells (PSCs). This study assessed the effect of HGF/c-MET inhibition plus gemcitabine (G) on the progression of advanced PC.

Methods

Orthotopic PC was produced by implantation of luciferase-tagged human cancer cells + human PSCs into mouse pancreas. Tumours were allowed to develop without treatment for 4 weeks. Mice were then treated for 6 weeks with one of the following: IgG, G, HGF inhibitor (Hi), c-MET inhibitor (Ci), Hi + Ci, Hi + G, Ci + G, or Hi + Ci + G.

Results

Bioluminescence imaging showed similar tumour sizes in all mice at the initiation of treatments. Triple therapy (Hi + Ci + G): (1) completely eliminated metastasis; (2) significantly reduced tumour size as assessed by bioluminescence and at necropsy; (3) significantly reduced proliferating cancer cell density and stem cell marker DCLK1 expression in tumours. In vitro 3D culture studies supported our in vivo findings.

Conclusion

Even at an advanced disease stage, a two-pronged approach, targeting (a) HGF/c-MET with relevant inhibitors and (b) cancer cells with chemotherapy, completely eliminated metastasis and significantly decreased tumour growth, suggesting that this is a promising treatment approach for PC.

Evaluation of the wound healing efficacy of chemical and phytogenic silver nanoparticles

Wound healing requires a series of cellular events and a cascade of co-ordinated and systemic biochemical events. Silver nanoparticles possess many beneficial properties for wound management including antibacterial, anti-inflammatory and pro-healing properties. In this study, the authors investigated the wound healing properties of Cinnamomum verum extract mediated nanosilver (CENS) particles in comparison with 1% povidone iodine, citrate mediate NS and CE treatments. The topical application of CENS showed good antibacterial activity and accelerated wound healing with complete epithelialisation and normal re-growth of hair in all three models of study: namely, excision, incision and dead space models in rats compared with all other treatments. CENS was also found to promote collagen synthesis, stabilise wound besides countering oxidative stress and stimulating cellular proliferation CENS could be a novel therapeutic agent for wound management.