Pancreatic Ductal Adenocarcinoma: Characteristics of Tumor Microenvironment and Barriers to Treatment

Pulse and CW EPR Oximetry Using Oxychip in Gemcitabine-Treated Murine Pancreatic Tumors

PURPOSE

The goal of this work was to compare pO2 measured using both continuous wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopy. The Oxychip particle spin probe enabled longitudinal monitoring of pO2 in murine pancreatic tumor treated with gemcitabine during the course of therapy.

PROCEDURES

Pancreatic PanO2 tumors were growing in the syngeneic mice, in the leg. Five doses of saline in control animals or gemcitabine were administered every 3 days, and pO2 was measured after each dose at several time points. Oxygen partial pressure was determined from the linewidth of the CW EPR signal (Bruker E540L) or from the T2 measured using the electron spin echo sequence (Jiva-25™).

RESULTS

The oxygen sensitivity was determined from a calibration curve as 6.1 mG/mm Hg in CW EPR and 68.5 ms-1/mm Hg in pulse EPR. A slight increase in pO2 of up to 20 mm Hg was observed after the third dose of gemcitabine compared to the control. The maximum delta pO2 during the therapy correlated with better survival.

CONCLUSIONS

Both techniques offer fast and reliable oximetry in vivo, allowing to follow the effects of pharmaceutic intervention.

High beta integrin expression is differentially associated with worsened pancreatic ductal adenocarcinoma outcomes

Outcomes in pancreatic ductal adenocarcinoma (PDAC) are known to be worse in tumors with high integrin β1 expression, but targeted monotherapy against this integrin has not been effective. Seven other beta integrins are expressed in mammalian biology and they are known to have overlapping and compensatory signaling in biological systems. However, their roles in PDAC are poorly understood and have not been systematically compared to integrin β1 biology. In this study, we analyzed the clinical outcomes against beta integrin 1-8 (ITGB1-8) expression in PDAC samples from two large independent cohorts, The Cancer Genome Atlas (TCGA) and GSE21501. Biological function and tumor microenvironment composition were studied using Gene Set Enrichment Analysis and xCell. Expression of all eight beta integrins is significantly increased in PDACs relative to normal pancreatic tissues (all P<0.001). ITGB1, 2, 5, and 6 have similarly enriched gene patterns related to transforming growth factor (TGF)-β, epithelial mesenchymal transition, inflammation, stemness, and angiogenesis pathways. Homologous recombination defects and neoantigens are increased in high-ITGB4, 5, and 6 tumors, with decreased overall survival in high-ITGB1, 5, and 6 tumors compared to low expression tumors (hazard ratios 1.5-2.0). High-ITGB1, 2, and 5 tumors have increased fibroblast infiltration (all P<0.01) while endothelial cells are increased in high-ITGB2 and 3 tumors (all P<0.05). Overall, beta integrin expression does not correlate to immune cell populations in PDACs. Therefore, while all beta integrins are overexpressed in PDACs, they exert differential effects on PDAC biology. ITGB2, 5, and 6 have a similar profile to ITGB1, suggesting that future research in PDAC integrin therapy needs to consider the complementary signaling profiles mediated by these integrins.

The novel subclusters based on cancer-associated fibroblast for pancreatic adenocarcinoma

Introduction

Pancreatic adenocarcinoma (PAAD) is a fatal disease characterized by promoting connective tissue proliferation in the stroma. Activated cancer-associated fibroblasts (CAFs) play a key role in fibrogenesis in PAAD. CAF-based tumor typing of PAAD has not been explored.

Methods

We extracted single-cell sequence transcriptomic data from GSE154778 and CRA001160 datasets from Gene Expression Omnibus or Tumor Immune Single-cell Hub to collect CAFs in PAAD. On the basis of Seurat packages and new algorithms in machine learning, CAF-related subtypes and their top genes for PAAD were analyzed and visualized. We used CellChat package to perform cell-cell communication analysis. In addition, we carried out functional enrichment analysis based on clusterProfiler package. Finally, we explored the prognostic and immunotherapeutic value of these CAF-related subtypes for PAAD.

Results

CAFs were divided into five new subclusters (CAF-C0, CAF-C1, CAF-C2, CAF-C3, and CAF-C4) based on their marker genes. The five CAF subclusters exhibited distinct signaling patterns, immune status, metabolism features, and enrichment pathways and validated in the pan-cancer datasets. In addition, we found that both CAF-C2 and CAF-C4 subgroups were negatively correlated with prognosis. With their top genes of each subclusters, the sub-CAF2 had significantly relations to immunotherapy response in the patients with pan-cancer and immunotherapy.

Discussion

We explored the heterogeneity of five subclusters based on CAF in signaling patterns, immune status, metabolism features, enrichment pathways, and prognosis for PAAD.

Intraoperative radiation therapy induces immune response activity after pancreatic surgery

Background

Pancreatic cancer has highly aggressive features, such as local recurrence that leads to significantly high morbidity and mortality and recurrence after successful tumour resection. Intraoperative radiation therapy (IORT), which delivers targeted radiation to a tumour bed, is known to reduce local recurrence by directly killing tumour cells and modifying the tumour microenvironment.

Methods

Among 30 patients diagnosed with pancreatic cancer, 17 patients received IORT immediately after surgical resection. We investigated changes in the immune response induced by IORT by analysing the peritoneal fluid (PF) and blood of patients with and without IORT treatment after pancreatic cancer surgery. Further, we treated three pancreatic cell lines with PF to observe proliferation and activity changes.

Results

Levels of cytokines involved in the PI3K/SMAD pathway were increased in the PF of IORT-treated patients. Moreover, IORT-treated PF inhibited the growth, migration, and invasiveness of pancreatic cancer cells. Changes in lymphocyte populations in the blood of IORT-treated patients indicated an increased immune response.

Conclusions

Based on the characterisation and quantification of immune cells in the blood and cytokine levels in the PF, we conclude that IORT induced an anti-tumour effect by activating the immune response, which may prevent pancreatic cancer recurrence.

Clinical trial registration

NCT03273374.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08807-3.