Regulation of pancreatic cancer therapy resistance by chemokines

CXCL Gene Clusters Regulated by Enhancer-Mediated DNA Looping Alteration in Pancreatic Cancer Cells

Pancreatic cancer is one of the deadliest cancers. Chemokines affect the progression of pancreatic cancer through various mechanisms. Most of the CXC chemokine genes, CC chemokine genes and CX3C chemokine genes are clustered together within a very short region of chromatin. Transcription activity of gene clusters is usually influenced by the chromatin architecture and spatial organisation. Nevertheless, the chromatin-mediated regulatory mechanism on transcription of chemokine gene clusters has never been studied in pancreatic cancer. Herein, we determined that the expression of C-X-C motif chemokine ligand 8 (CXCL8), CXCL6, CXCL4L1, CXCL1, CXCL4, CXCL7, CXCL5, CXCL3 and CXCL2 was up-regulated, whereas CXCL9, CXCL10 and CXCL11 were down-regulated in pancreatic cancer cells compared with normal duct epithelial cells and further uncovered that four enhancer elements showed robust interaction to form DNA looping containing the up-regulated eight CXCL genes, whereas the other enhancer controlled CXCL9, CXCL10 and CXCL11 to form another DNA loop. Furthermore, after these enhancers were respectively destroyed by CRISPR-Cas9, we observed that the interaction with other enhancers was weakened as well as the expression of CXCL gene clusters and the tumour malignancy of pancreatic cancer cells was significantly changed. Taken together, our research exhibits the regulatory mechanism on transcription of CXCL gene clusters via enhance-dependent DNA looping alteration in pancreatic cancer cells.

RAW264.7 Macrophages as a Polarization Model in the Context of Pancreatic Cancer and Chemokine Release

The TME is a critical niche for determining the fate of cancer therapy. Tumor cells often polarize nontumor cells, including immune cells, in the TME to favor cancer growth. In pancreatic cancer, macrophages are associated with poor therapy outcomes and unfavorable survival, especially when rendered into M2 macrophages. The latter show features also found in so-called tumor-associated macrophages (TAM), which are described as protecting and propelling tumor growth. In this context, it has been understudied which pancreatic cancer chemokines contribute to macrophage polarization. To this end, we analyzed murine RAW264.7 macrophages and Panc02 and PDA6606 pancreatic cancer cells in mono- and coculture to identify release patterns of 13 chemokines. Artificial macrophage polarization confirmed prominent changes in surface receptor and chemokine secretion profiles. Strikingly, RAW264.7 cocultures with Panc02 or PDA6606 were congruent in showing elevated levels of CCL2, CCL5, CCL17, CCL20, CCL22, CXCL5, and CXCL10. Further underlining the suitability of our in vitro model, both pancreatic cancer cell lines showed similar modulation of the critical macrophage polarization markers arginase, CD206, and iNOS, as well as chemokine receptors CCR2 and CCR4. Collectively, we demonstrated that our model is suitable for testing the roles and functions of chemokines in macrophage polarization by pancreatic cancer cells.

SIN3B Loss Heats up Cold Tumor Microenvironment to Boost Immunotherapy in Pancreatic Cancer

Despite progress significant advances in immunotherapy for some solid tumors, pancreatic ductal adenocarcinoma (PDAC) remains unresponsive poorly responsive to such interventions, largely due to its highly immunosuppressive tumor microenvironment (TME) with limited CD8+ T cell infiltration. This study explores the role of the epigenetic factor Sin3B in the PDAC TME. Using murine PDAC models, we found that tumor cell-intrinsic Sin3B loss reshapes the TME, increasing CD8+ T cell infiltration and cytotoxicity, thus impeding tumor progression and enhancing sensitivity to anti-PD1 treatment. Sin3B-deficient tumor cells exhibited amplified CXCL9/10 secretion in response to Interferon-gamma (IFNγ), creating a positive feedback loop via the CXCL9/10-CXCR3 axis, thereby intensifying the anti-tumor immune response against PDAC. Mechanistically, extensive epigenetic regulation is uncovered by Sin3B loss, particularly enhanced H3K27Ac distribution on genes related to immune responses in PDAC cells. Consistent with the murine model findings, analysis of human PDAC samples revealed a significant inverse correlation between SIN3B levels and both CD8+ T cell infiltration and CXCL9/10 expression. Notebly, PDAC patients with lower SIN3B expression showed a more favorable response to anti-PD1 therapy. The findings suggest that targeting SIN3B can enhance cytotoxic T cell infiltration into the tumor site and improve immunotherapy efficacy in PDAC, offering potential avenues for therapeutic biomarker or target in this challenging disease.

Ubiquitin modification in the regulation of tumor immunotherapy resistance mechanisms and potential therapeutic targets

Although immune checkpoint-based cancer immunotherapy has shown significant efficacy in various cancers, resistance still limits its therapeutic effects. Ubiquitination modification is a mechanism that adds different types of ubiquitin chains to proteins, mediating protein degradation or altering their function, thereby affecting cellular signal transduction. Increasing evidence suggests that ubiquitination modification plays a crucial role in regulating the mechanisms of resistance to cancer immunotherapy. Drugs targeting ubiquitination modification pathways have been shown to inhibit tumor progression or enhance the efficacy of cancer immunotherapy. This review elaborates on the mechanisms by which tumor cells, immune cells, and the tumor microenvironment mediate resistance to cancer immunotherapy and the details of how ubiquitination modification regulates these mechanisms, providing a foundation for enhancing the efficacy of cancer immunotherapy by intervening in ubiquitination modification.

Molecular understanding and clinical aspects of tumor-associated macrophages in the immunotherapy of renal cell carcinoma

Renal cell carcinoma (RCC) is one of the most common tumors that afflicts the urinary system, accounting for 90-95% of kidney cancer cases. Although its incidence has increased over the past decades, its pathogenesis is still unclear. Tumor-associated macrophages (TAMs) are the most prominent immune cells in the tumor microenvironment (TME), comprising more than 50% of the tumor volume. By interacting with cancer cells, TAMs can be polarized into two distinct phenotypes, M1-type and M2-type TAMs. In the TME, M2-type TAMs, which are known to promote tumorigenesis, are more abundant than M1-type TAMs, which are known to suppress tumor growth. This ratio of M1 to M2 TAMs can create an immunosuppressive environment that contributes to tumor cell progression and survival. This review focused on the role of TAMs in RCC, including their polarization, impacts on tumor proliferation, angiogenesis, invasion, migration, drug resistance, and immunosuppression. In addition, we discussed the potential of targeting TAMs for clinical therapy in RCC. A deeper understanding of the molecular biology of TAMs is essential for exploring innovative therapeutic strategies for the treatment of RCC.

Calpain 8 as a potential biomarker regulates the progression of pancreatic cancer via EMT and AKT/ERK pathway

Calpain is a non-lysozyme, calcium-dependent intracellular cysteine protease that has been shown to play a role in tumor proliferation, survival, migration, invasion, and apoptosis. Dysregulation of calpain expression is closely related to tumorigenesis. However, the role of calpain-8 (CAPN8), as a member of the calpain family, in pancreatic cancer (PC) is remains unclear. In elucidating the mechanism of CAPN8 in PC, a comprehensive bioinformatics analysis and in vitro experiments were conducted. The TCGA database was used to explore the expression level of CAPN8, and the results in PC tissues and cell lines were verified. Then, the correlation between CAPN8 and clinicopathological features was analyzed. Additionaly, promoter methylation, immune infiltration, and GO/KEGG enrichment analyses were performed. Lastly, the molecular mechanism of CAPN8 in PC was investigated by using cell counting kit (CCK) 8, transwell, wound healing, Western blot assays, and so on. Results indicate that CAPN8 was highly expressed in PC and correlated with poor prognosis and advanced TNM stage. In addition, a low level of immune infiltration was closely associated with the high expression level of CAPN8. Based on these findings, we hypothesized that CAPN8 is a potential biomarker that regulates progression of PC via EMT and the AKT/ERK pathway. SIGNIFICANCE: Through comprehensive biological information and in vitro experiments, CAPN8 has been confirmed to play an important role in regulating pancreatic cancer (PC) proliferation, migration and invasion. CAPN8 is found to be closely related to the diagnosis, survival and prognosis of PC. Above all, CAPN8 may be a potential biomarker for the diagnosis and prognosis of PC.

Ectopic CXCR2 expression cells improve the anti-tumor efficiency of CAR-T cells and remodel the immune microenvironment of pancreatic ductal adenocarcinoma

BACKGROUND

Recent progressions in CAR-T cell therapy against pancreatic ductal adenocarcinoma (PDAC) remain disappointing, which are partially attributed to the immunosuppressive microenvironment including macrophage-mediated T cell repletion.

METHODS

We first characterized the expression patterns of macrophage-relevant chemokines and identified CXCR2 as the key factor regulating T cell trafficking and tumor-specific accumulation in PDAC microenvironment. After that, we synthesized and introduced a CXCR2 expression cascade into Claudin18.2 CAR-T cells and compared the behaviors of CAR-T cells in vitro and in vivo. The therapeutic potential of CXCR2 CAR-T was evaluated in two different allogeneic models: subcutaneous allografts and metastatic PDAC models.

RESULTS

The results showed that CXCR2 CAR-T not only reduced the size of allografted PDAC tumors, but also completely eliminated the formation of metastases. Lastly, we investigated the tumor tissues and found that expression of ectopic CXCR2 significantly improved tumor-targeted infiltration and residence of T cells and reduced the presence of MDSCs and CXCR2 + macrophages in PDAC microenvironment.

CONCLUSION

Our studies suggested that ectopic CXCR2 played a significant and promising role in improving the efficiency of CAR-T therapy against primary and metastatic PDAC and partially reversed the immune-suppressive microenvironment.

Cancer-Associated Fibroblasts Promote Lymphatic Metastasis in Cholangiocarcinoma via the PDGF-BB/PDGFR-β Mediated Paracrine Signaling Network

Patients with cholangiocarcinoma (CCA) with lymph node metastasis (LNM) have the worst prognosis, even after complete resection; however, the underlying mechanism remains unclear. Here, we established CAF-derived PDGF-BB as a regulator of LMN in CCA. Proteomics analysis revealed upregulation of PDGF-BB in CAFs derived from patients with CCA with LMN (LN+CAFs). Clinically, the expression of CAF-PDGF-BB correlated with poor prognosis and increased LMN in patients with CCA, while CAF-secreted PDGF-BB enhanced lymphatic endothelial cell (LEC)-mediated lymphangiogenesis and promoted the trans-LEC migration ability of tumor cells. Co-injection of LN+CAFs and cancer cells increased tumor growth and LMN in vivo. Mechanistically, CAF-derived PDGF-BB activated its receptor PDGFR-β and its downstream ERK1/2-JNK signaling pathways in LECs to promote lymphoangiogenesis, while it also upregulated the PDGFR-β-GSK-P65-mediated tumor cell migration. Finally, targeting PDGF-BB/PDGFR-β or the GSK-P65 signaling axis prohibited CAF-mediated popliteal lymphatic metastasis (PLM) in vivo. Overall, our findings revealed that CAFs promote tumor growth and LMN via a paracrine network, identifying a promising therapeutic target for patients with advanced CCA.

The Role of Chemokines in Orchestrating the Immune Response to Pancreatic Ductal Adenocarcinoma

Chemokines are small molecules that function as chemotactic factors which regulate the migration, infiltration, and accumulation of immune cells. Here, we comprehensively assess the structural and functional role of chemokines, examine the effects of chemokines that are present in the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME), specifically those produced by cancer cells and stromal components, and evaluate their impact on immune cell trafficking, both in promoting and suppressing anti-tumor responses. We further explore the impact of chemokines on patient outcomes in PDAC and their role in the context of immunotherapy treatments, and review clinical trials that have targeted chemokine receptors and ligands in the treatment of PDAC. Lastly, we highlight potential strategies that can be utilized to harness chemokines in order to increase cytotoxic immune cell infiltration and the anti-tumor effects of immunotherapy.

Exosomes: Another intercellular lipometabolic communication mediators in digestive system neoplasms?

Neoplasms are one of the most concerned public health problems worldwide. Digestive system neoplasms, with a high morbidity and mortality, is one of the most common malignant tumors in human being. It is found that exosomes act as an intercellular communication media to carry the metabolic and genetic information of parental cells to target cells. Likely, exosomes participate in lipid metabolism and regulates multiple processes in digestive system neoplasms, including the information transmission among cancer cells, the formation of neoplastic microenvironment, and the neoplastic biological behaviors like metastasis, invasion, and the chemotherapy resistance. In this review, we firstly introduce the main mechanisms whereas exosomes act as intercellular lipometabolic communication mediator in digestive system neoplasms. Thereafter we introduce the relationship between exosomes lipid metabolism and various type of digestive system neoplasms, including gastric cancer, hepatocellular carcinoma, pancreatic cancer, and colorectal cancer. Eventually, we summarized and prospected the development and implication of exosomes in digestive system neoplasms. The further research of exosomes as intercellular lipid metabolism mediator will contribute to accurate and efficient diagnosis and treatment of digestive system neoplasms.

CCR4 Blockade Diminishes Intratumoral Macrophage Recruitment and Augments Survival of Syngeneic Pancreatic Cancer-Bearing Mice

Pancreatic cancer is known for its tumor microenvironment (TME), which is rich in stromal and immune cells supporting cancer growth and therapy resistance. In particular, tumor-associated macrophages (TAMs) are known for their angiogenesis- and metastasis-promoting properties, which lead to the failure of conventional therapies for pancreatic cancer. Hence, treatment options targeting TAMs are needed. The C-C chemokine receptor type 4 (CCR4) is critical for immune cell recruitment into the TME, and in this paper we explore the effects of its genetic or immunotherapeutic blockade in pancreatic-cancer-bearing mice. Murine PDA6606 pancreatic cancer cells and murine peritoneal macrophages were used for in vitro migration assays. In vivo, a syngeneic, orthotropic pancreatic cancer model was established. Tumor growth and survival were monitored under prophylactic and therapeutic application of a CCR4 antagonist (AF-399/420/18025) in wildtype (CCR4^wt) and CCR4-knockout (CCR4^-/-) mice. Immune infiltration was monitored in tumor tissue sections and via flow cytometry of lysed tumors. PDA6606 cells induced less migration in CCR4^-/- than in CCR4^wt macrophages in vitro. Pancreatic TAM infiltration was higher, and survival was reduced in CCR4^wt mice compared to CCR4^-/- mice. Antagonizing CCR4 in wildtype mice revealed similar results as in CCR4^-/- mice without antagonization. Prophylactic CCR4 antagonist application in wildtype mice was more efficient than therapeutic antagonization. CCR4 seems to be critically involved in TAM generation and tumor progression in pancreatic cancer. CCR4 blockade may help prolong the relapse-free period after curative surgery in pancreatic cancer and improve prognosis.

DA7R: A 7-Letter Zip Code to Target PDAC

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer, and is among the most aggressive and still incurable cancers. Innovative and successful therapeutic strategies are extremely needed. Peptides represent a versatile and promising tool to achieve tumor targeting, thanks to their ability to recognize specific target proteins (over)expressed on the surface of cancer cells. A7R is one such peptide, binding neuropilin-1 (NRP-1) and VEGFR2. Since PDAC expresses these receptors, the aim of this study was to test if A7R-drug conjugates could represent a PDAC-targeting strategy. PAPTP, a promising mitochondria-targeted anticancer compound, was selected as the cargo for this proof-of-concept study. Derivatives were designed as prodrugs, using a bioreversible linker to connect PAPTP to the peptide. Both the retro-inverso (DA7R) and the head-to-tail cyclic (cA7R) protease-resistant analogs of A7R were tested, and a tetraethylene glycol chain was introduced to improve solubility. Uptake of a fluorescent DA7R conjugate, as well as of the PAPTP-DA7R derivative into PDAC cell lines was found to be related to the expression levels of NRP-1 and VEGFR2. Conjugation of DA7R to therapeutically active compounds or nanovehicles might allow PDAC-targeted drug delivery, improving the efficacy of the therapy and reducing off-target effects.

Novel chemokine related LncRNA signature correlates with the prognosis, immune landscape, and therapeutic sensitivity of esophageal squamous cell cancer

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is closely correlated with malignant biological characteristics and poor survival. Recently, chemokines have been reported to be involved in the progression of tumors, and they can also regulate the tumor microenvironment. However, it is unclear whether chemokine-related long noncoding RNAs (lncRNAs) affect the prognosis of ESCC.

METHODS

We downloaded RNA-seq and clinical data from the Gene Expression Omnibus (GEO database. Chemokine-related lncRNAs were screened by differential analysis and Pearson correlation analysis. Then, prognosis-related lncRNAs were screened by using univariate COX regression, and risk models were constructed after the least absolute shrinkage and selection operator (LASSO) regression and multivariate COX regression. The predictive value of the signature was assessed using Kaplan-Meier test, time-dependent receiver operating characteristic (ROC) curves, decision curve analysis (DCA) and calibration curve. Moreover, a nomogram to predict patients' 1-year 3-year and 5-year prognosis was constructed. Gene set enrichment analyses (GSEA), Gene Ontology/Kyoto Encyclopedia of Genes and Genomes (GO/KEGG), evaluation of immune cell infiltration, and estimation of drug sensitivity were also conducted.

RESULTS

In this study, 677 chemokine-related lncRNAs were first obtained by differential analysis and Pearson correlation. Then, six chemokine-related lncRNAs were obtained by using univariate COX, LASSO and multivariate COX to construct a novel chemokine-related lncRNAs risk model. The signature manifested favorable predictive validity and accuracy both in the testing and training cohorts. The chemokine-related signature could classify ESCC patients into two risk groups well, which indicated that high-risk group exhibited poor prognostic outcome. In addition, this risk model played an important role in predicting signaling pathways, immune cell infiltration, stromal score, and drug sensitivity in ESCC patients.

CONCLUSIONS

These findings elucidated the critical role of novel prognostic chemokine-related lncRNAs in prognosis, immune landscape, and drug therapy, thus throwing light on prognostic evaluation and therapeutic targets for ESCC patients.

The role of macrophages in the tumor microenvironment and tumor metabolism

The complexity and plasticity of the tumor microenvironment (TME) make it difficult to fully understand the intratumoral regulation of different cell types and their activities. Macrophages play a crucial role in the signaling dynamics of the TME. Among the different subtypes of macrophages, tumor-associated macrophages (TAMs) are often associated with poor prognosis, although some subtypes of TAMs can at the same time improve treatment responsiveness and lead to favorable clinical outcomes. TAMs are key regulators of cancer cell proliferation, metastasis, angiogenesis, extracellular matrix remodeling, tumor metabolism, and importantly immunosuppression in the TME by modulating various chemokines, cytokines, and growth factors. TAMs have been identified as a key contributor to resistance to chemotherapy and cancer immunotherapy. In this review article, we aim to discuss the mechanisms by which TAMs regulate innate and adaptive immune signaling in the TME and summarize recent preclinical research on the development of therapeutics targeting TAMs and tumor metabolism.

A Novel Prognostic Chemokine-Related lncRNAs Signature Associated with Immune Landscape in Colon Adenocarcinoma

Chemokines have been reported to be involved in tumorigenesis and progression and can also modulate the tumor microenvironment. However, it is still unclear whether chemokine-related long noncoding RNAs (lncRNAs) can affect the prognosis of colon adenocarcinoma (COAD). We summarized chemokine-related genes and downloaded RNA-seq and clinical data from The Cancer Genome Atlas (TCGA) database. A total of 52 prognostic chemokine-related lncRNAs were screened by univariate Cox regression analysis; patients were grouped according to cluster analysis results. Lasso regression analysis was applied to determine chemokine-related lncRNAs to construct a risk model for further research. This study first investigated the differences between the prognosis and immune status of two chemokine-related lncRNAs clusters by consensus clustering. Then, using various algorithms, we obtained ten chemokine-related lncRNAs to construct a new prognostic chemokine-related lncRNAs risk model. The risk model's predictive efficiency, validity, and accuracy were further validated and determined in the test and training cohorts. Furthermore, this risk model played a vital role in predicting immune cell infiltration, immune checkpoint gene expression, tumor mutational burden (TMB), immunotherapy score, and drug sensitivity in COAD patients. These findings elucidated the critical role of novel prognostic chemokine-related lncRNAs in prognosis, immune landscape, and drug therapy, thereby providing valuable insights for prognosis assessment and personalized treatment strategies for COAD patients.