Fatty Acid-Mediated Stromal Reprogramming of Pancreatic Stellate Cells Induces Inflammation and Fibrosis That Fuels Pancreatic Cancer

Decoding tumor-fibrosis interplay: mechanisms, impact on progression, and innovative therapeutic strategies

Malignant tumors are a category of diseases that possess invasive and metastatic capabilities, with global incidence and mortality rates remaining high. In recent years, the pivotal role of fibrosis in tumor progression, drug resistance, and immune evasion has increasingly been acknowledged. Fibrosis enhances the proliferation, migration, and invasion of tumor cells by modifying the composition and structure of the extracellular matrix, thereby offering protection for immune evasion by tumor cells. The activation of cancer-associated fibroblasts (CAFs) plays a significant role in this process, as they further exacerbate the malignant traits of tumors by secreting a variety of cytokines and growth factors. Anti-fibrotic tumor treatment strategies, including the use of anti-fibrotic drugs and inhibition of fibrosis-related signaling pathways such as Transforming Growth Factor-β (TGF-β), have demonstrated potential in delaying tumor progression and improving the effectiveness of chemotherapy, targeted therapy, and immunotherapy. In the future, by developing novel drugs that target the fibrotic microenvironment, new therapeutic options may be available for patients with various refractory tumors.

Lipid metabolism associated crosstalk: the bidirectional interaction between cancer cells and immune/stromal cells within the tumor microenvironment for prognostic insight

Cancer is closely related to lipid metabolism, with the tumor microenvironment (TME) containing numerous lipid metabolic interactions. Cancer cells can bidirectionally interact with immune and stromal cells, the major components of the TME. This interaction is primarily mediated by fatty acids (FAs), cholesterol, and phospholipids. These interactions can lead to various physiological changes, including immune suppression, cancer cell proliferation, dissemination, and anti-apoptotic effects on cancer cells. The physiological modulation resulting from this lipid metabolism-associated crosstalk between cancer cells and immune/stromal cells provides valuable insights into cancer prognosis. A comprehensive literature review was conducted to examine the function of the bidirectional lipid metabolism interactions between cancer cells and immune/stromal cells within the TME, particularly how these interactions influence cancer prognosis. A novel autophagy-extracellular vesicle (EV) pathway has been proposed as a mediator of lipid metabolism interactions between cancer cells and immune cells/stromal cells, impacting cancer prognosis. As a result, different forms of lipid metabolism interactions have been described as being linked to cancer prognosis, including those mediated by the autophagy-EV pathway. In conclusion, understanding the bidirectional lipid metabolism interactions between cancer cells and stromal/immune cells in the TME can help develop more advanced prognostic approaches for cancer patients.

Pancreatic parenchymal changes seen on endoscopic ultrasound are dynamic in the setting of fatty pancreas: A short-term follow-up study

OBJECTIVES

The impact of fatty pancreas on pancreatic parenchymal changes is unclear. The aim of this study is to assess parenchymal alterations over time in patients with fatty pancreas (FP).

METHODS

This is a retrospective study (2014-2021) of patients with FP identified on endoscopic ultrasound (EUS). Subjects with follow up imaging studies including Computed Tomography (CT) scan, Magnetic Resonance Imaging (MRI), and EUS at least two years after the initial EUS were included.

RESULTS

A total of 39 patients with a mean age of 51.21 ± 12.34 years were included. Mean initial weight was 80.17 ± 17.75 kg. Diabetes, hepatic steatosis, and EPI were present in 15%, 46% and 33% of the patients at baseline, respectively. In 25 patients with available follow up EUS over 2.4 ± 0.76 years, 16% progressed to chronic pancreatitis (CP) and 24% had progressive parenchymal changes without meeting the criteria for CP. One patient progressed from focal to diffuse FP, while one patient had resolution of FP. In multivariate analysis, progressive parenchymal changes on EUS were associated with an increase in weight over time (p-value 0.04), independent of the effects of gender, alcohol, or tobacco.

CONCLUSION

Progressive parenchymal changes were noted in 44%. Our result suggests that FP is a dynamic process with the possibility of progression or regression over time.

Pancreatic CT density is an optimal imaging biomarker for earlier detection of malignancy in the pancreas with intraductal papillary mucinous neoplasm

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are typically detected as incidental findings by computed tomography (CT); however, the conventional surveillance is not valid for the early detection of concomitant pancreatic cancer. The pancreas of IPMN is often accompanied by fatty infiltration in the parenchyma, and pancreatic fatty infiltration could be evaluated by pancreatic CT density (pancreatic index, PI). We aimed to investigate whether PI could be an imaging biomarker for the early prediction of malignancies in the pancreas with IPMN.

METHODS

Two different cohorts were investigated. (Investigation cohort): A total of 1137 patients with initially low-risk IPMN were compensated by initial IPMN findings, and 2 groups (malignancy/possible benign, 50 cases each) were investigated for yearly changes in PI and for the cutoff value of PI indicating the development of malignancies. (Validation cohort): To validate the cutoff value, 256 patients radiologically suspected of having IPMNs were investigated.

RESULTS

(Investigation-cohort): The malignancy group showed a gradual decrease in PI every year, and PI significantly differed among the 2 groups 1 year prior to the last investigation. The cutoff value of PI was set at 0.65. (Validation-cohort): A total of 55% of the patients with a PI below the cutoff value had malignancy in the pancreas, including concomitant pancreatic cancer, and the cutoff value was the most significant risk factors for the development of malignancies in the pancreas compared to the conventional risk factors for IPMN.

CONCLUSIONS

Decreasing PI would be an optimal imaging biomarker for earlier detection of malignancies in the pancreas with IPMN.

Ponicidin suppresses pancreatic cancer growth by inducing ferroptosis: Insight gained by mass spectrometry-based metabolomics

BACKGROUND

Pancreatic cancer is one of the most common malignant tumors of the digestive tract. Ponicidin, a tetracyclic diterpenoid active ingredient extracted from the traditional phytomedicine Rubescens, has high safety and great inhibitory effect on the proliferation of a variety of cancer cells, especially malignant tumor cells of the digestive tract. However, the inhibitory effect and mechanism of ponicidin on pancreatic cancer cells is still unclear. Our study aimed to use metabonomics technology to analyze and explore the suppressive effect of ponidicin against pancreatic cancer cells.

METHODS

MTT and flow cytometry were conducted to study the potential effect of ponicidin on SW1990 cells. Secondly, UPLC-MS/MS was used to analyze the small molecule metabolites and relevant differential metabolic pathways induced by ponicidin treatment. Furthermore, through the determination of glutathione peroxidase 4 (GPX4) activity and molecular docking simulation experiments, the effects of intracellular GPX4 activity and GSH/GSSG ratio after ponicidin were evaluated. Finally, the determination of the content of iron ions and malondialdehyde in cells, and the experiment of the effect of ferroptosis inhibitors on cell viability, the effect of ponicidin on the induction of ferroptosis in SW1990 cells was also detected.

RESULTS

The IC50 of ponicidin on SW1990 cells was 20 μM, which could significantly induce cell apoptosis and arrest the cells in G2/M phase. Metabolomics results showed that the contents of endogenous small molecules such as gamma-glutamylcysteine, 5-oxoproline, glutamic acid, reduced glutathione (GSH), oxidized glutathione (GSSG) and arachidonic acid have changed significantly. Main differential compounds were involved in the gamma-glutamyl cycle and polyunsaturated fatty acid metabolism of pancreatic cancer cell lines. Additionally, ponicidin could covalently bind to GSH in SW1990 cells to form a conjugate Pon-GSH, which further reduced the content of free GSH and GPX4 activity in cells. Notably, ponicidin dose-dependently increased levels of iron ions, malondialdehyde and reactive oxygen species in SW1990 cells, and the ferroptosis inhibitors could significantly block the effects of ponicidin on the proliferation of SW1990 cells.

CONCLUSION

Ponicidin could suppress the pancreatic cancer cell proliferation via inducing ferroptosis by inhibiting the gamma-glutamyl cycle and regulating the polyunsaturated fatty acid metabolism in SW1990 cells.

The dynamic behavior of lipid droplets in the pre-metastatic niche

The pre-metastatic niche is a favorable microenvironment for the colonization of metastatic tumor cells in specific distant organs. Lipid droplets (LDs, also known as lipid bodies or adiposomes) have increasingly been recognized as lipid-rich, functionally dynamic organelles within tumor cells, immune cells, and other stromal cells that are linked to diverse biological functions and human diseases. Moreover, in recent years, several studies have described the indispensable role of LDs in the development of pre-metastatic niches. This review discusses current evidence related to the biogenesis, composition, and functions of LDs related to the following characteristics of the pre-metastatic niche: immunosuppression, inflammation, angiogenesis/vascular permeability, lymphangiogenesis, organotropism, reprogramming. We also address the function of LDs in mediating pre-metastatic niche formation. The potential of LDs as markers and targets for novel antimetastatic therapies will be discussed.

Clinical Utility of Bile Duct Axis Deviation for Differential Diagnosis Between Pancreatic Head Cancer and Bile Duct Cancer

BACKGROUNDS

Differential diagnosis between pancreatic head cancer (PHC) and intrapancreatic bile duct cancer (BDC) is important, but no clinical standard has been established. Here we examine the diagnostic utility of bile duct axis deviation and other clinical factors for this differential diagnosis.

METHODS

This study enrolled patients who underwent pancreaticoduodenectomy for PHC or BDC at our center between 2009 and 2016. PHCs in groove or uncinate portions were excluded from analysis. From contrast-enhanced computed tomography images, the bile duct angle (BDA) was measured using three points: the junction of intrahepatic bile ducts, upper pancreatic edge, and Vater papilla. Logistic regression was performed to evaluate the diagnostic performance of BDA and other clinical factors for differential diagnosis.

RESULTS

During the study period, 22 PHCs and 31 BDCs were resected. The combination of BDA ≤ 130°, main pancreatic duct diameter ≥ 4.3 mm, and absence of jaundice predicted PHC rather than BDC with an area under the curve of the receiver-operator characteristics curve of .856 (95% confidence interval, .766-.947).

CONCLUSION

Clinical findings of larger bile duct axis deviation, main pancreatic duct dilation, and the absence of jaundice may be useful for distinguishing PHC from BDC.

Investigation of human pancreatic cancer tissues by Fourier Transform Infrared Hyperspectral Imaging

Fourier-transform infrared hyperspectral imaging (FTIR-HSI) provides hyperspectral images containing both morphological and chemical information. It is widely applied in the biomedical field to detect tumor lesions, even at the early stage, by identifying specific spectral biomarkers. Pancreatic neoplasms present different prognoses and are not always easily classified by conventional analyses. In this study, tissue samples with diagnosis of pancreatic ductal adenocarcinoma and pancreatic neuroendocrine tumor were analyzed by FTIR-HSI and the spectral data compared with those from healthy and dysplastic samples. Multivariate/univariate approaches were complemented to hyperspectral images, and definite spectral markers of the different lesions identified. The malignant lesions were recognizable both from healthy/dysplastic pancreatic tissues (high values of phospholipids and triglycerides with shorter, more branched and less unsaturated alkyl chains) and between each other (different amounts of total lipids, phosphates and carbohydrates). These findings highlight different metabolic pathways characterizing the different samples, well detectable by FTIR-HSI.

Impact of fatty pancreas and lifestyle on the development of subclinical chronic pancreatitis in healthy people undergoing a medical checkup

Background

Although fat accumulation in human organs is associated with a variety of diseases, there is little evidence about the effect of a fatty pancreas on the development of subclinical chronic pancreatitis over the clinical course.

Methods

We conducted a prospective cohort study from 2008 to 2014 of patients who underwent a medical checkup consultation for fat accumulated in the pancreas. Patients included in the analysis were divided into a non-fatty pancreas group (n = 9710) and fatty pancreas group (n = 223). The primary end point was the odds ratio (OR) for chronic pancreatitis associated with fatty pancreas, which was diagnosed using ultrasonography. We used a multiple logistic regression model to estimate the OR and the corresponding 95% confidence interval (CI).

Results

Ninety-two people were diagnosed with chronic pancreatitis, including both presumptive and definitive diagnoses. Twelve people were diagnosed with chronic pancreatitis by ultrasonography among the 223 patients with fatty pancreas, and 80 patients among 9710 were diagnosed with non-fatty pancreas. The crude OR was 6.85 (95% CI 3.68, 12.75), and the multiple adjusted OR was 3.96 (95% CI 2.04, 7.66).

Conclusions

Fat accumulation in the pancreas could be a risk factor for developing subclinical chronic pancreatitis.

Pancreatic Stellate Cells Serve as a Brake Mechanism on Pancreatic Acinar Cell Calcium Signaling Modulated by Methionine Sulfoxide Reductase Expression

Although methionine sulfoxide reductase (Msr) is known to modulate the activity of multiple functional proteins, the roles of Msr in pancreatic stellate cell physiology have not been reported. In the present work we investigated expression and function of Msr in freshly isolated and cultured rat pancreatic stellate cells. Msr expression was determined by RT-PCR, Western blot and immunocytochemistry. Msr over-expression was achieved by transfection with adenovirus vectors. Pancreatic stellate cells were co-cultured with pancreatic acinar cells AR4-2J in monolayer culture. Pancreatic stellate and acinar cell function was monitored by Fura-2 calcium imaging. Rat pancreatic stellate cells were found to express MsrA, B1, B2, their expressions diminished in culture. Over-expressions of MsrA, B1 or B2 were found to enhance ATP-stimulated calcium increase but decreased reactive oxygen species generation and lipopolysaccharide-elicited IL-1 production. Pancreatic stellate cell-co-culture with AR4-2J blunted cholecystokinin- and acetylcholine-stimulated calcium increases in AR4-2J, depending on acinar/stellate cell ratio, this inhibition was reversed by MsrA, B1 over-expression in stellate cells or by Met supplementation in the co-culture medium. These data suggest that Msr play important roles in pancreatic stellate cell function and the stellate cells may serve as a brake mechanism on pancreatic acinar cell calcium signaling modulated by stellate cell Msr expression.

Pancreatic stellate cells facilitate pancreatic cancer cell viability and invasion

The biological features of pancreatic cancer and the associated hypoxic environment around the cancer cells often lead to resistance to radiotherapy and chemotherapy. The present study was performed in order to explore the effect pancreatic stellate cells (PSCs) have on the proliferation of pancreatic cancer cells. In the present study, PSCs from human pancreatic cancer tissues were isolated, and the PSCs markers α-smooth muscle actin and desmin were overexpressed in the cytoplasm of PSCs. An MTT assay revealed that PSCs promoted the viability of pancreatic cancer cells. However, the viability of pancreatic cancer cells promoted by PSCs was partially blocked by SB525334. Cellular invasion analysis demonstrated that PSCs promoted the invasion ability of pancreatic cancer cells. An apoptosis assay indicated that PSCs decreased the level of apoptosis induced by gemcitabine. In vivo experiments consisting of mice bearing MIA-PaCa-2 and PSCs demonstrated an increase in the rate of tumor growth compared with MIA-PaCA-2 alone, whereas SB525334 may delay the tumor progression induced by PSCs. The present findings indicated that PSCs promoted the viability and invasion of pancreatic cancer cells, and decreased the apoptosis of pancreatic cancer cells induced by gemcitabine.

Bile duct angulation and tumor vascularity are useful radiographic features for differentiating pancreatic head cancer and intrapancreatic bile duct cancer

BACKGROUND AND PURPOSE

To perform radical resection without leaving residual cancer, surgeons must distinguish between pancreatic head cancer (PHC) and intrapancreatic bile duct cancer (IPBDC) preoperatively. The aim of this study was to establish the points of difference between these two cancers, especially on preoperative multi-detector computed tomography (MDCT) images.

METHODS

The subjects of this study were 28 patients with PHC and proven bile duct invasion who underwent pancreatoduodenectomy (PHC group) and 22 patients with IPBDC and upstream bile duct dilation (IPBDC group). We compared the preoperative clinical and radiographic features, including the bile duct angle, calculated on coronal images of MDCT, and the vascularity of the tumor.

RESULTS

The optimal cut-off values for the bile duct angle, the CT value ratio of the tumor (late arterial phase/non-enhanced), and the main pancreatic duct (MPD) ratio (diameter of MPD/diameter of parenchyma) were 110°, 3.0, and 0.2, respectively. Multivariate analysis revealed that a bile duct angle < 110°, a CT value ratio of the tumor < 3, and an MPD ratio ≥ 0.2 were independently associated with PHC.

CONCLUSIONS

A bile duct angle and CT value reflecting the vascularity of the tumor might be useful radiographic features for differentiating PHC and IPBDC, in addition to MPD dilatation.