Dynamic immunoediting by macrophages in homologous recombination deficiency-stratified pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease, notably resistant to existing therapies. Current research indicates that PDAC patients deficient in homologous recombination (HR) benefit from platinum-based treatments and poly-ADP-ribose polymerase inhibitors (PARPi). However, the effectiveness of PARPi in HR-deficient (HRD) PDAC is suboptimal, and significant challenges remain in fully understanding the distinct characteristics and implications of HRD-associated PDAC. We analyzed 16 PDAC patient-derived tissues, categorized by their homologous recombination deficiency (HRD) scores, and performed high-plex immunofluorescence analysis to define 20 cell phenotypes, thereby generating an in-situ PDAC tumor-immune landscape. Spatial phenotypic-transcriptomic profiling guided by regions-of-interest (ROIs) identified a crucial regulatory mechanism through localized tumor-adjacent macrophages, potentially in an HRD-dependent manner. Cellular neighborhood (CN) analysis further demonstrated the existence of macrophage-associated high-ordered cellular functional units in spatial contexts. Using our multi-omics spatial profiling strategy, we uncovered a dynamic macrophage-mediated regulatory axis linking HRD status with SIGLEC10 and CD52. These findings demonstrate the potential of targeting CD52 in combination with PARPi as a therapeutic intervention for PDAC.

Inflammatory cytokine-regulated tRNA-derived fragment tRF-21 suppresses pancreatic ductal adenocarcinoma progression.

The tumorigenic mechanism for pancreatic ductal adenocarcinoma (PDAC) is not clear, although chronic inflammation is implicated. Here, we identified an inflammatory cytokine-regulated transfer RNA-derived (tRNA-derived) fragment, tRF-21-VBY9PYKHD (tRF-21), as a tumor suppressor in PDAC progression. We found that the biogenesis of tRF-21 could be inhibited by leukemia inhibitory factor and IL-6 via the splicing factor SRSF5. Reduced tRF-21 promoted AKT2/1-mediated heterogeneous nuclear ribonucleoprotein L (hnRNP L) phosphorylation, enhancing hnRNP L to interact with dead-box helicase 17 (DDX17) to form an alternative splicing complex. The provoked hnRNP L-DDX17 activity preferentially spliced Caspase 9 and mH2A1 pre-mRNAs to form Caspase 9b and mH2A1.2, promoting PDAC cell malignant phenotypes. The tRF-21 levels were significantly lower in PDACs than in normal tissues, and patients with low tRF-21 levels had a poor prognosis. Treatment of mouse PDAC xenografts or patient-derived xenografts (PDXs) with tRF-21 mimics repressed tumor growth and metastasis. These results demonstrate that tRF-21 has a tumor-suppressive effect and is a potential therapeutic agent for PDAC.

Genome-wide identification and characterization of circular RNA m6A modification in pancreatic cancer.

BACKGROUND: N6-methyladenosine (m6A) is the most abundant modification of RNA in eukaryotic cells and play critical roles in cancer. While most related studies focus on m6A modifications in linear RNA, transcriptome-wide profiling and exploration of m6A modification in circular RNAs in cancer is still lacking. METHODS: For the detection of m6A modification in circRNAs, we developed a new bioinformatics tools called Circm6A and applied it to the m6A-seq data of 77 tissue samples from 58 individuals with pancreatic ductal adenocarcinoma (PDAC). RESULTS: Circm6A performs better than the existing circRNA identification tools, which achieved highest F1 score among these tools in the detection of circRNAs with m6A modifications. By using Circm6A, we identified a total of 8807 m6A-circRNAs from our m6A-seq data. The m6A-circRNAs tend to be hypermethylated in PDAC tumor tissues compared with normal tissues. The hypermethylated m6A-circRNAs were associated with a significant gain of circRNA-mRNA coexpression network, leading to the dysregulation of many important cancer-related pathways. Moreover, we found the cues that hypermethylated m6A-circRNAs may promote the circularization and translation of circRNAs. CONCLUSIONS: These comprehensive findings further bridged the knowledge gaps between m6A modification and circRNAs fields by depicting the m6A-circRNAs genomic landscape of PDAC patients and revealed the emerging roles played by m6A-circRNAs in pancreatic cancer. Circm6A is available at https://github.com/canceromics/circm6a .

A novel anastomosis technique facilitates pancreaticojejunostomy in total laparoscopic pancreaticoduodenectomy (with video).

BACKGROUND: While the best technique for pancreatic anastomosis during Whipple's procedure remains controversial, laparoscopic pancreaticoduodenectomy (LPD) has been rapidly increasing in popularity. Because of their feasibility and reliability, new pancreatic anastomosis techniques may have vital roles when adapted for LPD. Here, we describe a new pancreaticojejunostomy (PJ) technique using three sutures (termed the "three sutures" PJ technique), which facilitates pancreatic anastomosis during total LPD. METHODS: A total of 149 patients who underwent LPD using the "three sutures" PJ technique at three hospitals were included in this study (81 patients at Guangdong Provincial People's Hospital [GDPH], 60 patients at Sun Yat-Sen Memorial Hospital [SMH], and 8 patients at Affiliated Hospital of Guangdong Medical University [AHGMU]). Data on the demographic characteristics, operative outcomes, and postoperative results (pancreatic fistula rate, mortality rate, and length of hospital stay) of these patients were collected and analyzed. RESULTS: A surgical video showing the details of the "three sutures" PJ method was included. The mean operation times at GDPH, SMH, and AHGMU were 4.08 ± 0.99 h, 4.65 ± 1.53 h, and 4.67 ± 0.64 h, respectively, and the average PJ times were 17.96 ± 3.49 min, 18.19 ± 2.63 min, and 22.5 ± 3.96 min, respectively. The numbers of grade B pancreatic fistulas were 9 (11.11%), 2 (3.33%), and 1 (12.50%), respectively, and two patients had grade C fistulas, one each at GDPH and SMH. The numbers of clinically relevant postoperative pancreatic fistula (CR-POPF) were 10 (12.35%), 3 (5.00%), and 1 (12.50%) in each center, respectively. The overall rate of CR-POPF was 9.40% (14/149) among patients of all three centers. The perioperative mortality rate was 0%. CONCLUSIONS: The "three sutures" PJ technique for total LPD is a safe and reliable method, with a low risk of pancreatic fistula, short anastomosis time, and steep learning curve.

N6 -methyladenosine-Mediated Upregulation of WTAPP1 Promotes WTAP Translation and Wnt Signaling to Facilitate Pancreatic Cancer Progression.

Pseudogenes may play important roles in cancer. Here, we explore the mechanism and function of a pseudogene WTAPP1 in the progress of pancreatic ductal adenocarcinoma (PDAC). WTAPP1 RNA was significantly elevated in PDAC and was associated with poor prognosis in patients. Overexpression of WTAPP1 RNA promoted PDAC proliferation and invasiveness in vitro and in vivo. Mechanistically, N 6-methyladenosine (m6A) modification stabilized WTAPP1 RNA via CCHC-type zinc finger nucleic-acid binding protein (CNBP), resulting in increased levels of WTAPP1 RNA in PDAC cells. Excessive WTAPP1 RNA bound its protein-coding counterpart WT1-associated protein (WTAP) mRNA and recruited more EIF3 translation initiation complex to promote WTAP translation. Increased WTAP protein enhanced the activation of Wnt signaling and provoked the malignant phenotypes of PDAC. Decreasing WTAPP1 RNA significantly suppressed the in vivo growth and metastasis of PDAC cell lines and patient-derived xenografts. These results indicate that m6A-mediated increases in WTAPP1 expression promote PDAC progression and thus may serve as a therapeutic target. SIGNIFICANCE: This study reveals how aberrant m6A modification of the WTAPP1 pseudogene results in increased translation of its protein-coding counterpart to promote Wnt signaling, which contributes to pancreatic cancer progression.

LINC00842 inactivates transcription co-regulator PGC-1α to promote pancreatic cancer malignancy through metabolic remodelling.

The molecular mechanism underlying pancreatic ductal adenocarcinoma (PDAC) malignancy remains unclear. Here, we characterize a long intergenic non-coding RNA LINC00842 that plays a role in PDAC progression. LINC00842 expression is upregulated in PDAC and induced by high concentration of glucose via transcription factor YY1. LINC00842 binds to and prevents acetylated PGC-1α from deacetylation by deacetylase SIRT1 to form PGC-1α, an important transcription co-factor in regulating cellular metabolism. LINC00842 overexpression causes metabolic switch from mitochondrial oxidative catabolic process to fatty acid synthesis, enhancing the malignant phenotypes of PDAC cells. High LINC00842 levels are correlated with elevated acetylated- PGC-1α levels in PDAC and poor patient survival. Decreasing LINC00842 level and inhibiting fatty acid synthase activity significantly repress PDAC growth and invasiveness in mouse pancreatic xenograft or patient-derived xenograft models. These results demonstrate that LINC00842 plays a role in promoting PDAC malignancy and thus might serve as a druggable target.

Cancer-associated fibroblasts-mediated ATF4 expression promotes malignancy and gemcitabine resistance in pancreatic cancer via the TGF-ß1/SMAD2/3 pathway and ABCC1 transactivation.

Cancer-associated fibroblasts (CAFs) contribute to malignant progression and chemoresistance in pancreatic ductal adenocarcinoma (PDAC). However, little is known about the underlying mechanism. In this study, we investigated the potential role and mechanisms of activating transcription factor 4 (ATF4) in CAFs-induced malignancy and gemcitabine resistance. We demonstrated that ATF4 is overexpressed in PDAC and associated with a poor prognosis. Silencing ATF4 expression decreased proliferation, colony formation, migration, gemcitabine sensitivity, and sphere formation. Subsequently, we revealed that CAFs secrete TGF-ß1 to upregulate the expression of ATF4 in PDAC cells via the SMAD2/3 pathway and induce cancer progression, cancer stemness, and gemcitabine resistance. Furthermore, we demonstrated that ATF4 directly binds to the ABCC1 promoter region to activate transcription. In summary, these data demonstrate that CAFs contribute to malignancy and gemcitabine resistance in PDAC by upregulating the expression of ATF4 via the TGF-ß1/SMAD2/3 axis and highlight that ATF4 is an attractive therapeutic target for combating gemcitabine resistance in PDAC.

Macrophage-expressed CD51 promotes cancer stem cell properties via the TGF-ß1/smad2/3 axis in pancreatic cancer.

Macrophage-targeted therapy offers new options for intractable pancreatic ductal adenocarcinoma (PDAC), which has a low 5-year survival rate. However, the factors regulating the biological function and phenotype of macrophages in PDAC are incompletely understood. Here, we found that CD51 was positively associated with the poor prognosis of PDAC patients and was highly expressed on macrophages but not on pancreatic cancer cells. Subsequently, we found that CD51 was a marker of macrophages, which promoted the stemness of pancreatic cancer cells. Furthermore, knockdown of CD51 in macrophages drove macrophages toward an M1-like phenotype. Mechanistically, macrophage-expressed CD51 contributed to the acquisition of stemness traits of pancreatic cancer cells by regulating the TGF-ß1/smad2/3 pathway. Our data demonstrate the central role played by macrophage-expressed CD51 in the acquisition of stemness traits of pancreatic cancer cells through the paracrine induction of TGF-ß1. We first show the connection between the CD51/TGF-ß1/smad2/3 axis and PDAC cancer stem cell properties and then indicate that CD51-targeted therapy is a new therapeutic modality for PDAC.

Cancer-associated fibroblasts promote progression and gemcitabine resistance via the SDF-1/SATB-1 pathway in pancreatic cancer.

Cancer-associated fibroblasts (CAFs), a dominant component of the pancreatic tumor microenvironment, are mainly considered as promotors of malignant progression, but the underlying molecular mechanism remains unclear. Here, we show that SDF-1 secreted by CAFs stimulates malignant progression and gemcitabine resistance in pancreatic cancer, partially owing to paracrine induction of SATB-1 in pancreatic cancer cells. CAF-secreted SDF-1 upregulated the expression of SATB-1 in pancreatic cancer cells, which contributed to the maintenance of CAF properties, forming a reciprocal feedback loop. SATB-1 was verified to be overexpressed in human pancreatic cancer tissues and cell lines by quantitative real-time PCR, western blot, and immunohistochemical staining, which correlated with tumor progression and clinical prognosis in pancreatic cancer patients. We found that SATB-1 knockdown inhibited proliferation, migration, and invasion in SW1990 and PANC-1 cells in vitro, whereas overexpression of SATB-1 in Capan-2 and BxPC-3 cells had the opposite effect. Immunofluorescence staining showed that conditioned medium from SW1990 cells expressing SATB-1 maintained the local supportive function of CAFs. Furthermore, downregulation of SATB-1 inhibited tumor growth in mouse xenograft models. In addition, we found that overexpression of SATB-1 in pancreatic cancer cells participated in the process of gemcitabine resistance. Finally, we investigated the clinical correlations between SDF-1 and SATB-1 in human pancreatic cancer specimens. In summary, these findings demonstrated that the SDF-1/CXCR4/SATB-1 axis may be a potential new target of clinical interventions for pancreatic cancer patients.

The Regulation of Mesenchymal Stem Cell Therapy Through Magnetic Resonance Imaging Agents-Based Cellular Condition and Oxygen Environment.

Repairing articular cartilage defects is difficult due to the hypovascular biostructure and poor self-repairing capacity of articular cartilage. Currently, mesenchymal stem cells (MSCs) with excellent differentiation potential are considered as a promising biological approach for cartilage regeneration. The effect, however, remains far from satisfactory for clinical applications owing to the main drawbacks of tracking the retention of cells and a low differentiation efficiency. As known, the nanoparticles with superparamagnetic properties has been used to monitor the MSCs in vivo through magnetic resonance imaging (MRI) in clinical application. In this study, different external and internal bio-conditions were applied to regulate the biological behavior of cells. Here, intracellular MRI contrast agents, superparamagnetic iron oxide nanocrystals (SPIONs), and a hypoxic culture environment were found to exert synergistic effects on gene and protein expression, and the cell viability, cell cycle, apoptosis, reactive oxygen species and the stem cell differentiations were measured. The levels of chondrogenic and migrant markers (including collagen II, collagen X, aggrecan, SOX9, MMPs and CXCR4) increased, triggering directional differentiation and enhancing cell migration to the inflammatory site. Moreover, SPION-labeled hypoxia-preconditioned MSCs were found without reactive oxygen species generation and transplanted into rat models with articular cartilage disorders. Interestingly, MRI and histological identification confirmed that new cartilage-like tissue was regenerated and that defects were repaired, and this method is more efficient for cartilage regeneration than SPION-labeled normoxia MSCs. The synergistic effect of hypoxia-precondition and SPIONs based cellular iron source could improve the cell migration and facilitate chondrogenic differentiation.

LncRNA HOTAIR epigenetically suppresses miR-122 expression in hepatocellular carcinoma via DNA methylation.

BACKGROUND: MicroRNA-122 (miR-122), a pivotal liver-specific miRNA, is frequently repressed in hepatocellular carcinoma (HCC) and associated with poor prognosis. Long non-coding RNA (lncRNA) HOTAIR has been proved to function as an oncogene in multiple cancers including HCC. However, the relationship between HOTAIR and miR-122 in HCC remains largely unknown. METHODS: We investigated the function of HOTAIR and miR-122 in HCC cell models and a xenograft mouse model. The regulatory network between HOTAIR and miR-122 was further detected following overexpression or knockdown of HOTAIR. DNA methylation status of miR-122 promoter region, as well as expression levels of DNMTs, EZH2 and Cyclin G1 were analyzed. FINDINGS: In this study, we found that HOTAIR was highly expressed whereas miR-122 was suppressed in HCC, and HOTAIR negatively regulated miR-122 expression in HCC cells. Furthermore, knockdown of HOTAIR dramatically inhibited HCC cell proliferation and induced cell cycle arrest in vitro and suppressed tumorigenicity in vivo by upregulating miR-122 expression. Mechanistically, a CpG island was located in the miR-122 promoter region. HOTAIR epigenetically suppressed miR-122 expression via DNMTs-mediated DNA methylation. Moreover, HOTAIR upregulated DNMTs expression via EZH2. In addition, suppression of miR-122 induced by HOTAIR directly reactivated oncogene Cyclin G1 expression. Collectively, our results suggest that HOTAIR epigenetically suppresses miR-122 expression via DNA methylation, leading to activation of Cyclin G1 and promotion of tumorigenicity in HCC, which provide new insight into the mechanism of HOTAIR-mediated hepatocarcinogenesis via suppressing miR-122.

Tumor-associated macrophages promote progression and the Warburg effect via CCL18/NF-kB/VCAM-1 pathway in pancreatic ductal adenocarcinoma.

Tumor-associated macrophages (TAMs) are frequently found near pancreatic cancer cells, but it is uncertain whether they are involved in pancreatic cancer progression and the Warburg effect. Here, we show that CCL18 secreted by TAMs facilitates malignant progression and induced a glycolytic phenotype in pancreatic cancer, partially owing to paracrine induction of VCAM-1 in pancreatic cancer cells. Reciprocally, VCAM-1-induced lactate production from pancreatic cancer cells with enhanced aerobic glycolysis activates macrophages to a TAM-like phenotype, forming a positive feedback loop. VCAM-1 was found to be highly expressed in human pancreatic ductal adenocarcinoma (PDAC) tissues and cell lines, and is associated with disease progression and predicts clinical outcome in PDAC patients. Flow cytometry analysis further demonstrated that VCAM-1 downregulation induced an accumulation of PDAC cells in G0/G1 phase, accompanied by a significant decrease in S phase. Downregulation of VCAM-1 significantly inhibited proliferation, colony formation, migration, and invasion of PDAC cells in vitro, whereas the ectopic expression of VCAM-1 had the opposite effect. VCAM-1 on pancreatic cancer cells might tethers THP-1 monocytes to cancer cells via counter-receptor interaction, providing a survival advantage to pancreatic cancer cells that infiltrate leukocyte-rich microenvironments. Furthermore, downregulation of VCAM-1 could repress tumor growth in mouse xenograft models. In particular, our results highlighted the contribution of VCAM-1 to the maintenance of the Warburg effect in PDAC cells. Finally, we investigated the clinical correlations of CCL18 and VCAM-1 in human PDAC specimens. In summary, these findings indicate that the CCL18/PITPNM3/NF-kB/VCAM-1 regulatory network might provide a potential new therapeutic strategy for PDAC.

FEZF1-AS1/miR-107/ZNF312B axis facilitates progression and Warburg effect in pancreatic ductal adenocarcinoma.

Long non-coding RNAs (lncRNAs) play a pivotal role in pathological processes. However, little information has been published regarding the underlying functions and mechanisms of lncRNAs in pancreatic ductal adenocarcinoma (PDAC). A novel lncRNA FEZF1-AS1 and its sense-cognate gene ZNF312B were found to be highly expressed in human PDAC tissues and cell lines, which is associated with disease progression and predicts clinical outcome in PDAC patients. Of note, bioinformatics analysis, luciferase assays and RNA immunoprecipitation assays indicated that FEZF1-AS1 may act as an endogenous sponge by competing for miR-107, thereby modulating the derepression of ZNF312B. Downregulation of FEZF1-AS1 or ZNF312B significantly inhibited proliferation, colony formation, migration, and invasion of PDAC cells in vitro, whereas the miR-107 inhibitor abrogated the effect of dow-regulation of FEZF1-AS1 or ZNF312B in reducing oncogenic capacities of PDAC cells. In addition, FEZF1-AS1/miR-107/ZNF312B axis-induced promotion of PDAC cells proliferation appeared to be mediated by modulation of the apoptosis and the G1-S checkpoint. Furthermore, downregulation of FEZF1-AS1 repressed tumor growth in mouse xenograft models. In particular, our results highlight the contribution of FEZF1-AS1/miR-107/ZNF312B axis to Warburg effect maintenance of PDAC cells. Collectively, our findings demonstrate that the FEZF1-AS1/miR-107/ZNF312B axis regulatory network might provide a potential new therapeutic strategy for PDAC.

Endogenous miRNA Sponge LincRNA-ROR promotes proliferation, invasion and stem cell-like phenotype of pancreatic cancer cells.

The long intergenic non-coding RNA, regulator of reprogramming (linc-ROR) is an oncogene and plays a key role in the embryonic stem cell maintenance and is involved in cancer progression. The objective of this study was to analyze linc-ROR expression in pancreatic ductal adenocarcinoma (PDAC) and determine the regulation effects of linc-ROR on proliferation and invasion of cancer cells, as well as properties of cancer stem-like cells (CSLCs). In this study, we found that linc-ROR was up-regulated in PDAC tissues and related to poor prognosis. Linc-ROR knockdown in pancreatic cancer cells inhibited cell growth and arrested in G1 phrase. Suppressed linc-ROR expression also attenuated cancer cell migration, invasion, and epithelial-mesenchymal transition. We observed that linc-ROR expression was increased in CSLCs. Importantly, linc-ROR knockdown impaired the properties and tumorigenesis of pancreatic CSLCs in vivo. Mechanistically, we found that linc-ROR functioned as a competing endogenous RNA (ceRNA) to several tumor suppressor microRNAs, particularly some members of let-7 family. We conclude that, as a crucial oncogene, linc-ROR promotes cell proliferation, invasiveness and contributes to stem cell properties of CSLCs in PDAC via acting as a ceRNA to regulate function of microRNAs. The linc-ROR is a potential therapeutic target for PDAC.

HIF-2α regulates non-canonical glutamine metabolism via activation of PI3K/mTORC2 pathway in human pancreatic ductal adenocarcinoma.

Hypoxia-inducible factor-2α (HIF-2α) plays an important role in increasing cancer progression and distant metastasis in a variety of tumour types. We aimed to investigate its biological function and clinical significance in human pancreatic ductal adenocarcinoma (PDAC). A total of 283 paired PDAC tissues and adjacent normal tissues were collected from patients who underwent surgery or biopsy at Sun Yat-sen Memorial Hospital between February 2004 and October 2016. In this study, we noted that HIF-2α expression was significantly up-regulated in PDAC, positively associated with disease stage, lymph-node metastasis and patient survival, and identified as an independent prognostic factor of PDAC patients. We demonstrated that HIF-2α silencing could reduce proliferation, migration and invasion of PDAC cells in vitro. The similar effect on growth was demonstrated in vivo. Furthermore, we noted that knock-down of HIF-2α significantly decreased the expression of glutamate oxaloacetate transaminase 1 (GOT1). Importantly, we confirmed that the PI3K/mTORC2 pathway promoted GOT1 expression by targeting HIF-2α. Our study validated HIF-2α was an important factor in PDAC progression and poor prognosis and may promote non-canonical glutamine metabolism via activation of PI3K/mTORC2 pathway. Targeting HIF-2α represents a novel prognostic biomarker and therapeutic target for patients with PDAC.