CTGF antagonism with mAb FG-3019 enhances chemotherapy response without increasing drug delivery in murine ductal pancreas cancer

A novel clinically relevant antagonistic interplay between prolactin and oncogenic YAP-CCN2 pathways as a differentiation therapeutic target in breast cancer

Cellular differentiation limits cellular plasticity allowing cells to attain their specialized functional characteristics and phenotypes, whereas loss of differentiation is a hallmark of cancer. Thus, characterizing mechanisms underlying differentiation is key to discover new cancer therapeutics. We report a novel functional antagonistic relationship between the prolactin (PRL)/prolactin receptor (PRLR) differentiation pathway and YAP-CCN2 oncogenic pathway in normal mammary epithelial cells and breast cancer cells that is essential for establishing/maintaining acinar morphogenesis, cell-cell junctions and the intracellular localization of apical-basal polarity protein complexes (Par, Crumb and Scrib). Importantly, using CRISPR knockout of the PRLR in MCF7, HR+ breast cancer cells, further revealed that the negative relationship between PRL/PRLR pathway and YAP-CCN2 pathway is critical in suppressing luminal-to-basal stem-like lineage plasticity. Furthermore, the clinical relevance of this interplay was evaluated using bioinformatics approaches on several human datasets, including samples from normal breast epithelium, breast cancer, and 33 other cancer types. This analysis revealed a positive correlation between PRLR and the YAP suppressor Hippo pathway and a co-expression gene network driving favourable patients' survival outcomes in breast cancer. The therapeutic potential of this interplay was also evaluated in vitro using MDA-MB-231 cells, a preclinical model of human triple-negative breast cancer, where treatment with PRL and Verteporfin, an FDA-approved pharmacological YAP-inhibitor, alone or their combination suppressed the expression of the mesenchymal marker vimentin and the stem cell marker CD44 as well as reduced their Ki67 proliferative marker expression. Collectively, our results emphasize the pro-differentiation role of PRL/PRLR pathway in mammary and breast cancer cells and highlight that promoting PRL/PRLR signaling while inhibiting the YAP-CCN2 oncogenic pathway can be exploited as a differentiation-based combination therapeutic strategy in breast cancer.

Cancer associated fibroblasts in cancer development and therapy

Cancer-associated fibroblasts (CAFs) are key players in cancer development and therapy, and they exhibit multifaceted roles in the tumor microenvironment (TME). From their diverse cellular origins, CAFs undergo phenotypic and functional transformation upon interacting with tumor cells and their presence can adversely influence treatment outcomes and the severity of the cancer. Emerging evidence from single-cell RNA sequencing (scRNA-seq) studies have highlighted the heterogeneity and plasticity of CAFs, with subtypes identifiable through distinct gene expression profiles and functional properties. CAFs influence cancer development through multiple mechanisms, including regulation of extracellular matrix (ECM) remodeling, direct promotion of tumor growth through provision of metabolic support, promoting epithelial-mesenchymal transition (EMT) to enhance cancer invasiveness and growth, as well as stimulating cancer stem cell properties within the tumor. Moreover, CAFs can induce an immunosuppressive TME and contribute to therapeutic resistance. In this review, we summarize the fundamental knowledge and recent advances regarding CAFs, focusing on their sophisticated roles in cancer development and potential as therapeutic targets. We discuss various strategies to target CAFs, including ECM modulation, direct elimination, interruption of CAF-TME crosstalk, and CAF normalization, as approaches to developing more effective treatments. An improved understanding of the complex interplay between CAFs and TME is crucial for developing new and effective targeted therapies for cancer.

Pancreatic CAF-Derived Autotaxin Drives Autocrine CTGF Expression to Modulate Protumorigenic Signaling

Autotaxin (ATX), encoded by ENPP2, is a clinical target in pancreatic ductal adenocarcinoma (PDAC). ATX catalyzes the production of lysophosphatidic acid (LPA), an important regulator within the tumor microenvironment (TME), yet the protumorigenic action of the ATX/LPA axis in PDAC remains unclear. In this study, by interrogating patient samples and cell line datasets, we show that the PDAC TME, rather than cancer cells, is responsible for the majority of ENPP2 expression and highlight a key role for cancer-associated fibroblast (CAF)-derived ATX in autocrine and paracrine protumorigenic signaling. Using the clinical-stage ATX inhibitor, IOA-289, we identified connective tissue growth factor (CTGF), also known as CCN2, as a downstream mediator of ATX signaling in the PDAC CAF-derived cell line, 0082T. Genetic ablation or pharmacologic inhibition of ATX in 0082T CAFs reduced CTGF secretion via modulation of LPA/LPA receptor signaling. Despite the loss of ATX function, extracellular levels of LPA were paradoxically increased, indicating a role for ATX beyond its enzymatic activity and suggesting a role for its LPA chaperone function in the LPA/LPA receptor signaling in CAFs. As CAFs are the main source for CTGF in the PDAC TME, these findings suggest a role for ATX in promoting a protumorigenic microenvironment via modulation of CAF secretion not only via its LPA-producing activity but also via its LPA chaperone function, providing a potential mechanism for the antitumor effects of ATX inhibition.

Targeting extracellular matrix stiffness for cancer therapy

The physical characteristics of the tumor microenvironment (TME) include solid stress, interstitial fluid pressure, tissue stiffness and microarchitecture. Among them, abnormal changes in tissue stiffness hinder drug delivery, inhibit infiltration of immune killer cells to the tumor site, and contribute to tumor resistance to immunotherapy. Therefore, targeting tissue stiffness to increase the infiltration of drugs and immune cells can offer a powerful support and opportunities to improve the immunotherapy efficacy in solid tumors. In this review, we discuss the mechanical properties of tumors, the impact of a stiff TME on tumor cells and immune cells, and the strategies to modulate tumor mechanics.

Targeting YAP Activity and Glutamine Metabolism Cooperatively Suppresses Tumor Progression by Preventing Extracellular Matrix Accumulation

Cancer cells use multiple mechanisms to evade the effects of glutamine metabolism inhibitors. The pathways that govern responses to alterations in glutamine availability within the tumor may represent therapeutic targets for combinatorial strategies with these inhibitors. Here, we showed that targeting glutamine utilization stimulated Yes-associated protein (YAP) signaling in cancer cells by reducing cyclic adenosine monophosphate/protein kinase A (PKA)-dependent phosphorylation of large tumor suppressor (LATS). Elevated YAP activation induced extracellular matrix (ECM) deposition by increasing the secretion of connective tissue growth factor that promoted the production of fibronectin and collagen by surrounding fibroblasts. Consequently, inhibiting YAP synergized with inhibition of glutamine utilization to effectively suppress tumor growth in vivo, along with a concurrent decrease in ECM deposition. Blocking ECM remodeling also augmented the tumor suppressive effects of the glutamine utilization inhibitor. Collectively, these data reveal mechanisms by which targeting glutamine utilization increases ECM accumulation and identify potential strategies to reduce ECM levels and increase the efficacy of glutamine metabolism inhibitors. Significance: Blocking glutamine utilization activates YAP to promote ECM deposition by fibroblasts, highlighting the potential of YAP inhibitors and antifibrotic strategies as promising approaches for effective combination metabolic therapies in cancer.

Pancreatic cancer: new approaches to drug therapy

Outcomes in pancreatic ductal adenocarcinoma (PDAC) remain poor due to a variety of biological, clinical, and societal factors. However, in recent years, PDAC has seen 1) increased precision of initial evaluation, 2) increased emphasis on supportive care, 3) deeper understanding of the translation biology of PDAC, especially as pertains to genomic alterations, and 4) foundational combination chemotherapy clinical trials across all disease stages. These advances have led to a wide range of new approaches to drug therapy for PDAC. Currently available drugs are showing added benefit, both by resequencing them with each other and also with respect to other therapeutic modalities. Molecular strategies are being developed to predict response to known therapeutic agents and to identify others. Additionally, a wide range of new drugs for PDAC are under development, including drugs which inhibit critical molecular pathways, drugs which attempt to capitalize on homologous repair deficiencies, immunotherapeutic approaches, antimetabolic agents, and drugs which attack the extracellular matrix which supports PDAC growth. These new approaches offer the promise of improved survival for future PDAC patients.

The reactive stroma response regulates the immune landscape in prostate cancer

Prostate cancer remains the most commonly diagnosed and the second leading cause of cancer-related deaths in men in the United States. The neoplastic transformation of prostate epithelia, concomitant with modulations in the stromal compartment, known as reactive stromal response, is critical for the growth, development, and progression of prostate cancer. Reactive stroma typifies an emergent response to disrupted tissue homeostasis commonly observed in wound repair and pathological conditions such as cancer. Despite the significance of reactive stroma in prostate cancer pathobiology, our understanding of the ontogeny, phenotypic and functional heterogeneity, and reactive stromal regulation of the immune microenvironment in prostate cancer remains limited. Traditionally characterized to have an immunologically "cold" tumor microenvironment, prostate cancer presents significant challenges for advancing immunotherapy compared to other solid tumors. This review explores the detrimental role of reactive stroma in prostate cancer, particularly its immunomodulatory function. Understanding the molecular characteristics and dynamic transcriptional program of the reactive stromal populations in tandem with tumor progression could offer insights into enhancing immunotherapy efficacy against prostate cancer.

YAP/TAZ enhances P-body formation to promote tumorigenesis

The role of processing bodies (P-bodies) in tumorigenesis and tumor progression is not well understood. Here, we showed that the oncogenes YAP/TAZ promote P-body formation in a series of cancer cell lines. Mechanistically, both transcriptional activation of the P-body-related genes SAMD4A, AJUBA, and WTIP and transcriptional suppression of the tumor suppressor gene PNRC1 are involved in enhancing the effects of YAP/TAZ on P-body formation in colorectal cancer (CRC) cells. By reexpression of PNRC1 or knockdown of P-body core genes (DDX6, DCP1A, and LSM14A), we determined that disruption of P-bodies attenuates cell proliferation, cell migration, and tumor growth induced by overexpression of YAP5SA in CRC. Analysis of a pancancer CRISPR screen database (DepMap) revealed co-dependencies between YAP/TEAD and the P-body core genes and correlations between the mRNA levels of SAMD4A, AJUBA, WTIP, PNRC1, and YAP target genes. Our study suggests that the P-body is a new downstream effector of YAP/TAZ, which implies that reexpression of PNRC1 or disruption of P-bodies is a potential therapeutic strategy for tumors with active YAP.

Expression of gemcitabine metabolizing enzymes and stromal components reveal complexities of preclinical pancreatic cancer models for therapeutic testing

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) poorly responds to antineoplastic agents. Discrepancies between preclinical success and clinical failure of compounds has been a continuous challenge and major obstacle in PDAC research.

AIM

To investigate the association of the tumor microenvironment (TME) composition and gemcitabine metabolizing enzyme (GME) expression in vitro and several in vivo models.

METHODS

mRNA expression and protein levels of GME (cytosolic 5'-nucleotidase 1 A; NT5C1A, cytidine deaminase; CDA, deoxycytidine kinase; DCK), gemcitabine transporters (ENT1, ENT2, RRM1, RRM2) and stromal components (hyaluroninc acid, podoplanin, masson trichrome, picrosirius) were assessed by qRT-PCR and immunohistochemistry in murine LSL-KrasG12D/+;LSL-Trp53R172 H/+; Pdx-1-Cre (KPC), orthotopically transplanted mice (OTM), human primary resected PDAC tissue (hPRT), corresponding patient-derived xenograft (PDX) mice, and KPC-SPARC-/- mice. mRNA expression of GME was analyzed in PDAC cell lines (Panc-1, MIA PaCa, BXPC3 and L3.6) upon incubation on collagen or pancreatic stellate cell (PSC) conditioned media by qRT-PCR.

RESULTS

Endogenous KPC tumors exhibited significantly higher levels of GME compared to OTM. However, GME levels did not differ between hPRT and corresponding PDX mice. Using Kendalls Tau correlation coefficient we did not show a significant correlation of GME and components of the TME except for NT5C1A and hyaluronic acid in PDX mice (p=0.029). GME were not significantly altered upon SPARC depletion in vivo, and upon treatment with PSC-conditioned media or incubation on collagen plated dishes in vitro.

CONCLUSIONS

Our findings suggest that the expression of GME is independent from the deposition of stromal components. KPC mice are most appropriate to study stromal composition whereas PDX mice maintain GME expression of the corresponding hPRT and could be best suited for pharmacokinetic studies.

The role of yes activated protein (YAP) in melanoma metastasis

Hippo was first identified in a genetic screen as a protein that suppressed proliferation and cell growth. Subsequently, it was shown that hippo acted in a so-called canonical cascade to suppress Yorkie, the Drosophila equivalent of Yes-activated protein (YAP), a mechanosensitive transcriptional cofactor that enhances the activity of the TEAD family of transcription factors. YAP promotes fibrosis, activation of cancer-associated fibroblasts, angiogenesis and cancer cell invasion. YAP activates the expression of the matricellular proteins CCN1 (cyr61) and CCN2 (ctgf), themselves mediators of fibrogenesis and oncogenesis, and coordination of matrix deposition and angiogenesis. This review discusses how therapeutically targeting YAP through YAP inhibitors verteporfin and celastrol and its downstream mediators CCN1 and CCN2 might be useful in treating melanoma.

Neoadjuvant management of locally advanced pancreatic ductal adenocarcinoma - Heading towards a promising change in treatment paradigm

Traditional chemotherapy-based adjuvant therapies for locally advanced pancreatic ductal adenocarcinoma (PDAC) have been associated with poor clinical outcomes driven partly by its complex anatomy and molecular heterogeneity. Treatment for PDAC is challenged by presence of a dense tumour microenvironment involving an interplay of multiple tumoural and stromal components which promote metastatic oncogenic behaviour. PDAC also involves aberrations in multiple signalling pathways with paucity of treatment options against the most common mutations including KRAS, TP53, CDKN2A andSMAD4. However, recent discovery of new mechanisms implicated in pancreatic carcinogenesis have led to identification of promising mechanistic therapeutic targets such as NET1 and ULK1. Early evidence also suggests the utility of targeting multiple DNA repair processes, modulators of DNA replication and major DNA damage response regulators. We explore the clinical rationale behind a neoadjuvant therapeutic strategy and emerging predictors of survival benefit associated with this approach. We also discuss challenges and opportunities originating from recent clinical trials evaluating neoadjuvant treatments composed of various combinations of radiotherapy, chemotherapy and immunotherapeutic regimens that have aimed to address some of these biological challenges. Selective treatment of patients harbouring specific genomic aberrations with targeted agents and immunotherapy can translate into optimum survival outcomes in PDAC. We also share perspectives on emerging prospective clinical evidence regarding stromal modifying agents, such as Tumour Growth Factor-Beta and Connective Tissue Growth Factor inhibitors along with novel vaccination-based approaches in improving PDAC outcomes.

Pirfenidone alleviates fibrosis by acting on tumour-stroma interplay in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy with a 5-year survival rate of 12%. The abundant mesenchyme is partly responsible for the malignancy. The antifibrotic therapies have gained attention in recent research. However, the role of pirfenidone, an FDA-approved drug for idiopathic pulmonary fibrosis, remains unclear in PDAC.

METHODS

Data from RNA-seq of patient-derived xenograft (PDX) models treated with pirfenidone were integrated using bioinformatics tools to identify the target of cell types and genes. Using confocal microscopy, qRT-PCR and western blotting, we validated the signalling pathway in tumour cells to regulate the cytokine secretion. Further cocultured system demonstrated the interplay to regulate stroma fibrosis. Finally, mouse models demonstrated the potential of pirfenidone in PDAC.

RESULTS

Pirfenidone can remodulate multiple biological pathways, and exerts an antifibrotic effect through inhibiting the secretion of PDGF-bb from tumour cells by downregulating the TGM2/NF-kB/PDGFB pathway. Thus, leading to a subsequent reduction in collagen X and fibronectin secreted by CAFs. Moreover, the mice orthotopic pancreatic tumour models demonstrated the antifibrotic effect and potential to sensitise gemcitabine.

CONCLUSIONS

Pirfenidone may alter the pancreatic milieu and alleviate fibrosis through the regulation of tumour-stroma interactions via the TGM2/NF-kB/PDGFB signalling pathway, suggesting potential therapeutic benefits in PDAC management.

An Update on Gemcitabine-Based Chemosensitization Strategies in Pancreatic Ductal Adenocarcinoma

Pancreatic cancer is the seventh leading cause of cancer-related deaths, and chemotherapy is one of the most important treatments for pancreatic cancer. Unfortunately, pancreatic cancer cells can block chemotherapy drugs from entering the tumor. This is owing to interactions between the tumor's environment and the cancer cells. Here, we review the latest research on the mechanisms by which pancreatic cancer cells block the chemotherapy drug, gemcitabine. The results of our review can help identify potential therapeutic targets for the blocking of gemcitabine by pancreatic cancer cells and may provide new strategies to help chemotherapy drugs penetrate tumors.

Use of Stromal Intervention and Exogenous Neoantigen Vaccination to Boost Pancreatic Cancer Chemo-Immunotherapy by Nanocarriers

Despite the formidable treatment challenges of pancreatic ductal adenocarcinoma (PDAC), considerable progress has been made in improving drug delivery via pioneering nanocarriers. These innovations are geared towards overcoming the obstacles presented by dysplastic stroma and fostering anti-PDAC immune reactions. We are currently conducting research aimed at enhancing chemotherapy to stimulate anti-tumor immunity by inducing immunogenic cell death (ICD). This is accomplished using lipid bilayer-coated nanocarriers, which enable the attainment of synergistic results. Noteworthy examples include liposomes and lipid-coated mesoporous silica nanoparticles known as "silicasomes". These nanocarriers facilitate remote chemotherapy loading, as well as the seamless integration of immunomodulators into the lipid bilayer. In this communication, we elucidate innovative ways for further improving chemo-immunotherapy. The first is the development of a liposome platform engineered by the remote loading of irinotecan while incorporating a pro-resolving lipoxin in the lipid bilayer. This carrier interfered in stromal collagen deposition, as well as boosting the irinotecan-induced ICD response. The second approach was to synthesize polymer nanoparticles for the delivery of mutated KRAS peptides in conjunction with a TLR7/8 agonist. The dual delivery vaccine particle boosted the generation of antigen-specific cytotoxic T-cells that are recruited to lymphoid structures at the cancer site, with a view to strengthening the endogenous vaccination response achieved by chemo-immunotherapy.

Module 4-Deficient CCN2/Connective Tissue Growth Factor Attenuates the Progression of Renal Fibrosis via Suppression of Focal Adhesion Kinase Phosphorylation in Tubular Epithelial Cells

CCN2/connective tissue growth factor (CTGF) potentially serves as a therapeutic target for chronic kidney disease. Here we investigated CCN2 module-4, encoded by Ccn2 exon 5, through the generation of Ccn2 exon 5 knockout mice (Ex5-/- mice). To investigate renal fibrosis pathogenesis, Ex5-/- mice were employed to model unilateral ureteral obstruction (UUO), unilateral ischemic-reperfusion injury (UIRI), and 5/6 nephrectomy. Interstitial fibrosis was significantly attenuated in the Ex5-/- mice in the three models. Furthermore, phosphorylated focal adhesion kinase (FAK) levels in tubular epithelial cells were significantly lower in the kidneys of the UUO- and UIRI-Ex5-/- mice than those of the Ex5+/+ mice. Moreover, CCN2 module 4-mediated renal tubule FAK and promoted fibrosis. These findings indicate that CCN2 module-4-FAK pathway components will serve as therapeutic targets for effectively attenuating renal fibrosis.

New insight into the role of fibroblasts in the epithelial immune microenvironment in the single-cell era

The skin is exposed to environmental challenges and contains heterogeneous cell populations such as epithelial cells, stromal cells, and skin-resident immune cells. As the most abundant type of stromal cells, fibroblasts have been historically considered silent observers in the immune responses of the cutaneous epithelial immune microenvironment (EIME), with little research conducted on their heterogeneity and immune-related functions. Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) have overcome the limitations of bulk RNA sequencing and help recognize the functional and spatial heterogeneity of fibroblasts, as well as their crosstalk with other types of cells in the cutaneous EIME. Recently, emerging single-cell sequencing data have demonstrated that fibroblasts notably participate in the immune responses of the EIME and impact the initiation and progression of inflammatory skin diseases. Here, we summarize the latest advances in the role of fibroblasts in the cutaneous EIME of inflammatory skin diseases and discuss the distinct functions and molecular mechanisms of activated fibroblasts in fibrotic skin diseases and non-fibrotic inflammatory skin diseases. This review help unveil the multiple roles of fibroblasts in the cutaneous EIME and offer new promising therapeutic strategies for the management of inflammatory skin diseases by targeting fibroblasts or the fibroblast-centered EIME.

Fibroblast diversity and plasticity in the tumor microenvironment: roles in immunity and relevant therapies

Cancer-associated fibroblasts (CAFs), enriched in the tumor stroma, have received increasing attention because of their multifaceted effects on tumorigenesis, development, metastasis, and treatment resistance in malignancies. CAFs contributed to suppressive microenvironment via different mechanisms, while CAFs also exerted some antitumor effects. Therefore, CAFs have been considered promising therapeutic targets for their remarkable roles in malignant tumors. However, patients with malignancies failed to benefit from current CAFs-targeted drugs in many clinical trials, which suggests that further in-depth investigation into CAFs is necessary. Here, we summarize and outline the heterogeneity and plasticity of CAFs mainly by exploring their origin and activation, highlighting the regulation of CAFs in the tumor microenvironment during tumor evolution, as well as the critical roles performed by CAFs in tumor immunity. In addition, we summarize the current immunotherapies targeting CAFs, and conclude with a brief overview of some prospects for the future of CAFs research in the end. Video Abstract.

Blocking CCN2 Reduces Established Palmar Neuromuscular Fibrosis and Improves Function Following Repetitive Overuse Injury

The matricellular protein cell communication factor 2/connective tissue growth factor (CCN2/CTGF) is critical to development of neuromuscular fibrosis. Here, we tested whether anti-CCN2 antibody treatment will reduce established forepaw fibro-degenerative changes and improve function in a rat model of overuse injury. Adult female rats performed a high repetition high force (HRHF) task for 18 weeks. Tissues were collected from one subset after 18 wks (HRHF-Untreated). Two subsets were provided 6 wks of rest with concurrent treatment with anti-CCN2 (HRHF-Rest/anti-CCN2) or IgG (HRHF-Rest/IgG). Results were compared to IgG-treated Controls. Forepaw muscle fibrosis, neural fibrosis and entheseal damage were increased in HRHF-Untreated rats, compared to Controls, and changes were ameliorated in HRHF-Rest/anti-CCN2 rats. Anti-CCN2 treatment also reduced phosphorylated-β-catenin (pro-fibrotic protein) in muscles and distal bone/entheses complex, and increased CCN3 (anti-fibrotic) in the same tissues, compared to HRHF-Untreated rats. Grip strength declines and mechanical sensitivity observed in HRHF-Untreated improved with rest; grip strength improved further in HRHF-Rest/anti-CCN2. Grip strength declines correlated with muscle fibrosis, entheseal damage, extraneural fibrosis, and decreased nerve conduction velocity, while enhanced mechanical sensitivity (a pain-related behavior) correlated with extraneural fibrosis. These studies demonstrate that blocking CCN2 signaling reduces established forepaw neuromuscular fibrosis and entheseal damage, which improves forepaw function, following overuse injury.

Inkjet-printed morphogenesis of tumor-stroma interface using bi-cellular bioinks of collagen-poly(N-isopropyl acrylamide-co-methyl methacrylate) mixture

Recent advances in biomaterials and 3D printing/culture methods enable various tissue-engineered tumor models. However, it is still challenging to achieve native tumor-like characteristics due to lower cell density than native tissues and prolonged culture duration for maturation. Here, we report a new method to create tumoroids with a mechanically active tumor-stroma interface at extremely high cell density. This method, named "inkjet-printed morphogenesis" (iPM) of the tumor-stroma interface, is based on a hypothesis that cellular contractile force can significantly remodel the cell-laden polymer matrix to form densely-packed tissue-like constructs. Thus, differential cell-derived compaction of tumor cells and cancer-associated fibroblasts (CAFs) can be used to build a mechanically active tumor-stroma interface. In this methods, two kinds of bioinks are prepared, in which tumor cells and CAFs are suspended respectively in the mixture of collagen and poly (N-isopropyl acrylamide-co-methyl methacrylate) solution. These two cellular inks are inkjet-printed in multi-line or multi-layer patterns. As a result of cell-derived compaction, the resulting structure forms tumoroids with mechanically active tumor-stroma interface at extremely high cell density. We further test our working hypothesis that the morphogenesis can be controlled by manipulating the force balance between cellular contractile force and matrix stiffness. Furthermore, this new concept of "morphogenetic printing" is demonstrated to create more complex structures beyond current 3D bioprinting techniques.

Polarization of Cancer-Associated Macrophages Maneuver Neoplastic Attributes of Pancreatic Ductal Adenocarcinoma

Mounting evidence links the phenomenon of enhanced recruitment of tumor-associated macrophages towards cancer bulks to neoplastic growth, invasion, metastasis, immune escape, matrix remodeling, and therapeutic resistance. In the context of cancer progression, naïve macrophages are polarized into M1 or M2 subtypes according to their differentiation status, gene signatures, and functional roles. While the former render proinflammatory and anticancer effects, the latter subpopulation elicits an opposite impact on pancreatic ductal adenocarcinoma. M2 macrophages have gained increasing attention as they are largely responsible for molding an immune-suppressive landscape. Through positive feedback circuits involving a paracrine manner, M2 macrophages can be amplified by and synergized with neighboring neoplastic cells, fibroblasts, endothelial cells, and non-cell autonomous constituents in the microenvironmental niche to promote an advanced disease state. This review delineates the molecular cues expanding M2 populations that subsequently convey notorious clinical outcomes. Future therapeutic regimens shall comprise protocols attempting to abolish environmental niches favoring M2 polarization; weaken cancer growth typically assisted by M2; promote the recruitment of tumoricidal CD8⁺ T lymphocytes and dendritic cells; and boost susceptibility towards gemcitabine as well as other chemotherapeutic agents.

Chemoresistance in pancreatic ductal adenocarcinoma: Overcoming resistance to therapy

Pancreatic ductal adenocarcinoma (PDAC), a prominent cause of cancer deaths worldwide, is a highly aggressive cancer most frequently detected at an advanced stage that limits treatment options to systemic chemotherapy, which has provided only marginal positive clinical outcomes. More than 90% of patients with PDAC die within a year of being diagnosed. PDAC is increasing at a rate of 0.5-1.0% per year, and it is expected to be the second leading cause of cancer-related mortality by 2030. The resistance of tumor cells to chemotherapeutic drugs, which can be innate or acquired, is the primary factor contributing to the ineffectiveness of cancer treatments. Although many PDAC patients initially responds to standard of care (SOC) drugs they soon develop resistance caused partly by the substantial cellular heterogeneity seen in PDAC tissue and the tumor microenvironment (TME), which are considered key factors contributing to resistance to therapy. A deeper understanding of molecular mechanisms involved in PDAC progression and metastasis development, and the interplay of the TME in all these processes is essential to better comprehend the etiology and pathobiology of chemoresistance observed in PDAC. Recent research has recognized new therapeutic targets ushering in the development of innovative combinatorial therapies as well as enhancing our comprehension of several different cell death pathways. These approaches facilitate the lowering of the therapeutic threshold; however, the possibility of subsequent resistance development still remains a key issue and concern. Discoveries, that can target PDAC resistance, either alone or in combination, have the potential to serve as the foundation for future treatments that are effective without posing undue health risks. In this chapter, we discuss potential causes of PDAC chemoresistance and approaches for combating chemoresistance by targeting different pathways and different cellular functions associated with and mediating resistance.

Overcoming the Fibrotic Fortress in Pancreatic Ductal Adenocarcinoma: Challenges and Opportunities

An overabundance of desmoplasia in the tumour microenvironment (TME) is one of the defining features that influences pancreatic ductal adenocarcinoma (PDAC) development, progression, metastasis, and treatment resistance. Desmoplasia is characterised by the recruitment and activation of fibroblasts, heightened extracellular matrix deposition (ECM) and reduced blood supply, as well as increased inflammation through an influx of inflammatory cells and cytokines, creating an intrinsically immunosuppressive TME with low immunogenic potential. Herein, we review the development of PDAC, the drivers that initiate and/or sustain the progression of the disease and the complex and interwoven nature of the cellular and acellular components that come together to make PDAC one of the most aggressive and difficult to treat cancers. We review the challenges in delivering drugs into the fortress of PDAC tumours in concentrations that are therapeutic due to the presence of a highly fibrotic and immunosuppressive TME. Taken together, we present further support for continued/renewed efforts focusing on aspects of the extremely dense and complex TME of PDAC to improve the efficacy of therapy for better patient outcomes.

Recent advances in targeted therapy for pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is a fatal disease with a 5-year survival rate of 8% and a median survival of 6 mo. In PDAC, several mutations in the genes are involved, with Kirsten rat sarcoma oncogene (90%), cyclin-dependent kinase inhibitor 2A (90%), and tumor suppressor 53 (75%–90%) being the most common. Mothers against decapentaplegic homolog 4 represents 50%. In addition, the self-preserving cancer stem cells, dense tumor microenvironment (fibrous accounting for 90% of the tumor volume), and suppressive and relatively depleted immune niche of PDAC are also constitutive and relevant elements of PDAC. Molecular targeted therapy is widely utilized and effective in several solid tumors. In PDAC, targeted therapy has been extensively evaluated; however, survival improvement of this aggressive disease using a targeted strategy has been minimal. There is currently only one United States Food and Drug Administration-approved targeted therapy for PDAC – erlotinib, but the absolute benefit of erlotinib in combination with gemcitabine is also minimal (2 wk). In this review, we summarize current targeted therapies and clinical trials targeting dysregulated signaling pathways and components of the PDAC oncogenic process, analyze possible reasons for the lack of positive results in clinical trials, and suggest ways to improve them. We also discuss emerging trends in targeted therapies for PDAC: combining targeted inhibitors of multiple pathways. The PubMed database and National Center for Biotechnology Information clinical trial website (www.clinicaltrials.gov) were queried to identify completed and published (PubMed) and ongoing (clinicaltrials.gov) clinical trials (from 2003-2022) using the keywords pancreatic cancer and targeted therapy. The PubMed database was also queried to search for information about the pathogenesis and molecular pathways of pancreatic cancer using the keywords pancreatic cancer and molecular pathways.

Emerging Role of Cancer-Associated Fibroblasts in Progression and Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide and the fourth leading cause of cancer-related death globally. Tumor cells recruit and remodel various types of stromal and inflammatory cells to form a tumor microenvironment (TME), which encompasses cellular and molecular entities, including cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), immune cells, myeloid-derived suppressor cells (MDSCs), immune checkpoint molecules and cytokines that promote cancer cell growth, as well as their drug resistance. HCC usually arises in the context of cirrhosis, which is always associated with an enrichment of activated fibroblasts that are owed to chronic inflammation. CAFs are a major component of the TME, providing physical support in it and secreting various proteins, such as extracellular matrices (ECMs), hepatocyte growth factor (HGF), insulin-like growth factor 1/2 (ILGF1/2) and cytokines that can modulate tumor growth and survival. As such, CAF-derived signaling may increase the pool of resistant cells, thus reducing the duration of clinical responses and increasing the degree of heterogeneity within tumors. Although CAFs are often implicated to be associated with tumor growth, metastasis and drug resistance, several studies have reported that CAFs have significant phenotypic and functional heterogeneity, and some CAFs display antitumor and drug-sensitizing properties. Multiple studies have highlighted the relevance of crosstalk between HCC cells, CAFs and other stromal cells in influence of HCC progression. Although basic and clinical studies partially revealed the emerging roles of CAFs in immunotherapy resistance and immune evasion, a better understanding of the unique functions of CAFs in HCC progression will contribute to development of more effective molecular-targeted drugs. In this review article, molecular mechanisms involved in crosstalk between CAFs, HCC cells and other stromal cells, as well as the effects of CAFs on HCC-cell growth, metastasis, drug resistance and clinical outcomes, are comprehensively discussed.

CXCL10 is a prognostic marker for pancreatic adenocarcinoma and tumor microenvironment remodeling

BACKGROUND

The tumor microenvironment (TME) plays a crucial role in the progression of pancreatic adenocarcinoma (PAAD). However, challenges remain regarding the role played by TME associated genes in the prognosis of PAAD.

METHODS

The scores of tumor infiltrating immune cells (TICs), the immune and stroma scores of 182 PAAD patients in the Cancer Genome Atlas (TCGA) database were determined using CIBERSORT and ESTIMATE calculations. The final genes were identified by protein-protein interaction (PPI) networks and univariate Cox regression of differentially expressed genes. Finally, the correlation between gene expression and TCGA and clinical characteristics of patients in local hospital database was discussed. Gene set enrichment analysis (GSEA), the association between CXCL10 expression and TICs components were conducted.

RESULTS

In TCGA database and local hospital data, CXCL10 expression was correlated with the survival rate and TNM classification of patients with PAAD. Immune-related activities were enriched in the CXCL10 high expression group, while metabolic pathways were enriched in the CXCL10 low expression group. The expression of CXCL10 correlated with the proportion of TICs. CXCL10 expression was correlated with the proportion of TICs.

CONCLUSION

CXCL10 is a potential prognostic marker for PAAD and provide additional insights into the treatment of PAAD based on TME transformation. However, more independent experimentation with the CXCL10 is need.

Therapeutic Strategies to Overcome Fibrotic Barriers to Nanomedicine in the Pancreatic Tumor Microenvironment

Pancreatic cancer is notorious for its dismal prognosis. The enhanced permeability and retention (EPR) effect theory posits that nanomedicines (therapeutics in the size range of approximately 10-200 nm) selectively accumulate in tumors. Nanomedicine has thus been suggested to be the "magic bullet"-both effective and safe-to treat pancreatic cancer. However, the densely fibrotic tumor microenvironment of pancreatic cancer impedes nanomedicine delivery. The EPR effect is thus insufficient to achieve a significant therapeutic effect. Intratumoral fibrosis is chiefly driven by aberrantly activated fibroblasts and the extracellular matrix (ECM) components secreted. Fibroblast and ECM abnormalities offer various potential targets for therapeutic intervention. In this review, we detail the diverse strategies being tested to overcome the fibrotic barriers to nanomedicine in pancreatic cancer. Strategies that target the fibrotic tissue/process are discussed first, which are followed by strategies to optimize nanomedicine design. We provide an overview of how a deeper understanding, increasingly at single-cell resolution, of fibroblast biology is revealing the complex role of the fibrotic stroma in pancreatic cancer pathogenesis and consider the therapeutic implications. Finally, we discuss critical gaps in our understanding and how we might better formulate strategies to successfully overcome the fibrotic barriers in pancreatic cancer.

Targeting the tumor stroma for cancer therapy

Tumors are comprised of both cancer cells and surrounding stromal components. As an essential part of the tumor microenvironment, the tumor stroma is highly dynamic, heterogeneous and commonly tumor-type specific, and it mainly includes noncellular compositions such as the extracellular matrix and the unique cancer-associated vascular system as well as a wide variety of cellular components including activated cancer-associated fibroblasts, mesenchymal stromal cells, pericytes. All these elements operate with each other in a coordinated fashion and collectively promote cancer initiation, progression, metastasis and therapeutic resistance. Over the past few decades, numerous studies have been conducted to study the interaction and crosstalk between stromal components and neoplastic cells. Meanwhile, we have also witnessed an exponential increase in the investigation and recognition of the critical roles of tumor stroma in solid tumors. A series of clinical trials targeting the tumor stroma have been launched continually. In this review, we introduce and discuss current advances in the understanding of various stromal elements and their roles in cancers. We also elaborate on potential novel approaches for tumor-stroma-based therapeutic targeting, with the aim to promote the leap from bench to bedside.

STAT3 is Activated by CTGF-mediated Tumor-stroma Cross Talk to Promote HCC Progression

BACKGROUND & AIMS

Signal transducer and activator of transcription 3 (STAT3) is known as a pro-oncogenic transcription factor. Regarding liver carcinogenesis, however, it remains controversial whether activated STAT3 is pro- or anti-tumorigenic. This study aimed to clarify the significance and mechanism of STAT3 activation in hepatocellular carcinoma (HCC).

METHODS

Hepatocyte-specific Kras-mutant mice (Alb-Cre KrasLSL-G12D/+; KrasG12D mice) were used as a liver cancer model. Cell lines of hepatoma and stromal cells including stellate cells, macrophages, T cells, and endothelial cells were used for culture. Surgically resected 12 HCCs were used for human analysis.

RESULTS

Tumors in KrasG12D mice showed up-regulation of phosphorylated STAT3 (p-STAT3), together with interleukin (IL)-6 family cytokines, STAT3 target genes, and connective tissue growth factor (CTGF). Hepatocyte-specific STAT3 knockout (Alb-Cre KrasLSL-G12D/+ STAT3fl/fl) downregulated p-STAT3 and CTGF and suppressed tumor progression. In coculture with stromal cells, proliferation, and expression of p-STAT3 and CTGF, were enhanced in hepatoma cells via gp130/STAT3 signaling. Meanwhile, hepatoma cells produced CTGF to stimulate integrin/nuclear factor kappa B signaling and up-regulate IL-6 family cytokines from stromal cells, which could in turn activate gp130/STAT3 signaling in hepatoma cells. In KrasG12D mice, hepatocyte-specific CTGF knockout (Alb-Cre KrasLSL-G12D/+ CTGFfl/fl) downregulated p-STAT3, CTGF, and IL-6 family cytokines, and suppressed tumor progression. In human HCC, single cell RNA sequence showed CTGF and IL-6 family cytokine expression in tumor cells and stromal cells, respectively. CTGF expression was positively correlated with that of IL-6 family cytokines and STAT3 target genes in The Cancer Genome Atlas.

CONCLUSIONS

STAT3 is activated by CTGF-mediated tumor-stroma crosstalk to promote HCC progression. STAT3-CTGF positive feedback loop could be a therapeutic target.

Therapeutic advances in metastatic pancreatic cancer: a focus on targeted therapies

Mortality from pancreatic ductal adenocarcinoma (PDAC) is increasing worldwide and effective new treatments are urgently needed. The current treatment of metastatic PDAC in fit patients is based on two chemotherapy combinations (FOLFIRINOX and gemcitabine plus nab-paclitaxel) which were validated more than 8 years ago. Although almost all treatments targeting specific molecular alterations have failed so far when administered to unselected patients, encouraging results were observed in the small subpopulations of patients with germline BRCA 1/2 mutations, and somatic gene fusions (neurotrophic tyrosine receptor kinase, Neuregulin 1, which are enriched in KRAS wild-type PDAC), KRAS G12C mutations, or microsatellite instability. While targeted tumor metabolism therapies and immunotherapy have been disappointing, they are still under investigation in combination with other drugs. Optimizing pharmacokinetics and adapting available chemotherapies based on molecular signatures are other promising avenues of research. This review evaluates the current expectations and limits of available treatments and analyses the existing trials. A permanent search for actionable vulnerabilities in PDAC tumor cells and microenvironments will probably result in a more personalized therapeutic approach, keeping in mind that supportive care must also play a major role if real clinical efficacy is to be achieved in these patients.

Emerging kinase inhibitors for the treatment of pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic cancer is one of the deadliest solid organ cancers. In the absence of specific warning symptoms pancreatic cancer is diagnosed notoriously late. Current systemic chemotherapy regimens extend survival by a mere few months. With the advances in genetic, proteomic, and immunological profiling there is strong rationale to test kinase inhibitors to improve outcome.

AREAS COVERED

This review article provides a comprehensive summary of approved treatments and past, present, and future developments of kinase inhibitors in pancreatic cancer. Emerging roles of protein kinase inhibitors are discussed in the context of the unique stroma, the lack of high-prevalence therapeutic targets and rapid emergence of acquired resistance, novel immuno-oncology kinase targets, and recent medicinal chemistry advances.

EXPERT OPINION

Due to the to-date frequent failure of protein kinase inhibitors indiscriminately administered to unselected pancreatic cancer patients, there is a shift toward the development of these agents in molecularly defined subgroups which are more likely to respond. The development of accurate biomarkers to select patients who are the best candidates based on a detailed understanding of mechanism of action, pro-survival roles, and mediation of resistance of targeted kinases will be critical for the future development of protein kinase inhibitors in this disease.

Role of drug catabolism, modulation of oncogenic signaling and tumor microenvironment in microbe-mediated pancreatic cancer chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) has one of the highest incidence/death ratios among all neoplasms due to its late diagnosis and dominant chemoresistance. Most PDAC patients present with an advanced disease characterized by a multifactorial, inherent and acquired resistance to current anticancer treatments. This remarkable chemoresistance has been ascribed to several PDAC features including the genetic landscape, metabolic alterations, and a heterogeneous tumor microenvironment that is characterized by dense fibrosis, and a cellular contexture including functionally distinct subclasses of cancer-associated fibroblasts, immune suppressive cells, but also a number of bacteria, shaping a specific tumor microbiome microenvironment. Thus, recent studies prompted the emergence of a new research avenue, by describing the role of the microbiome in gemcitabine resistance, while next-generation-sequencing analyses identified a specific microbiome in different tumors, including PDAC. Functionally, the contribution of these microbes to PDAC chemoresistance is only beginning to be explored. Here we provide an overview of the studies demonstrating that bacteria have the capacity to metabolically transform and hence inactivate anticancer drugs, as exemplified by the inhibition of the efficacy of 10 out of 30 chemotherapeutics by Escherichia coli. Moreover, a number of bacteria modulate specific oncogenic pathways, such as Fusobacterium nucleatum, affecting autophagy and apoptosis induction by 5-fluorouracil and oxaliplatin. We hypothesize that improved understanding of how chemoresistance is driven by bacteria could enhance the efficacy of current treatments, and discuss the potential of microbiome modulation and targeted therapeutic approaches as well as the need for more reliable models and biomarkers to translate the findings of preclinical/translational research to the clinical setting, and ultimately overcome PDAC chemoresistance, hence improving clinical outcome.

Identification of prognostic genes in the pancreatic adenocarcinoma immune microenvironment by integrated bioinformatics analysis

PURPOSE

Pancreatic adenocarcinoma (PAAD) is one of the most common causes of death among solid tumors, and its pathogenesis remains to be clarified. This study aims to elucidate the value of immune/stromal-related genes in the prognosis of PAAD through comprehensive bioinformatics analysis based on the immune microenvironment and validated in Chinese pancreatic cancer patients.

METHODS

Gene expression profiles of pancreatic cancer patients were obtained from TCGA database. Differentially expressed genes (DEGs) were identified based on the ESTIMATE algorithm. Gene co-expression networks were constructed using WGCNA. In the key module, survival analysis was used to reveal the prognostic value. Subsequently, we performed functional enrichment analysis to construct a protein-protein interaction (PPI) network. The relationship between tumor immune infiltration and hub genes was analyzed by TIMER and CIBERSORT. Finally, it was validated in the GEO database and in tissues of Chinese pancreatic cancer patients.

RESULTS

In the TCGA pancreatic cancer cohort, a low immune/stromal score was associated with a good prognosis. After bioinformatic analysis, 57 genes were identified to be significantly associated with pancreatic cancer prognosis. Among them, up-regulation of four genes (COL6A3, PLAU, MMP11 and MMP14) indicated poor prognosis and was associated with multiple immune cell infiltration. IHC results showed that PLAU protein levels from Chinese pancreatic cancer tissues were significantly higher than those from adjacent non-tumor tissues and were also associated with tumor TNM stage and lymph node metastasis.

CONCLUSION

In conclusion, this study demonstrates that PLAU may serve as a new diagnostic and therapeutic target, which is highly expressed in Chinese pancreatic cancer tissues and associated with lymph node metastasis.

Targeting Tumour-Associated Fibroblasts in Cancers

Tumours develop within complex tissue environments consisting of aberrant oncogenic cancer cells, diverse innate and adaptive immune cells, along with structural stromal cells, extracellular matrix and vascular networks, and many other cellular and non-cellular soluble constituents. Understanding the heterogeneity and the complex interplay between these cells remains a key barrier in treating tumours and cancers. The immune status of the pre-tumour and tumour milieu can dictate if the tumour microenvironment (TME) supports either a pro-malignancy or an anti-malignancy phenotype. Identification of the factors and cell types that regulate the dysfunction of the TME is crucial in order to understand and modulate the immune status of tumours. Among these cell types, tumour-associated fibroblasts are emerging as a major component of the TME that is often correlated with poor prognosis and therapy resistance, including immunotherapies. Thus, a deeper understanding of the complex roles of tumour-associated fibroblasts in regulating tumour immunity and cancer therapy could provide new insight into targeting the TME in various human cancers. In this review, we summarize recent studies investigating the role of immune and key stromal cells in regulating the immune status of the TME and discuss the therapeutic potential of targeting stromal cells, especially tumour-associated fibroblasts, within the TME as an adjuvant therapy to sensitize immunosuppressive tumours and prevent cancer progression, chemo-resistance and metastasis.

Activity of acute pancreatitis is modified by secreted protein acidic and rich in cysteine ablation

Background

Acute pancreatitis (AP) is a frequent cause for hospitalization. However, molecular determinants that modulate severity of experimental pancreatitis are only partially understood.

Objective

To investigate the role of secreted protein acidic and rich in cysteine (SPARC) during cerulein‐induced AP in mice.

Methods

AP was induced by repeated cerulein injections in SPARC knock‐out mice (SPARC^−/−) and control littermates (SPARC^+/+). Secreted protein acidic and rich in cysteine expression and severity of AP were determined by histopathological scoring, immunohistochemistry, and biochemical assays. For functional analysis, primary murine acinar cell cultures with subsequent amylase release assays were employed. Proteome profiler assay and ELISA were conducted from pancreatic tissue lysates, and co‐immunofluorescence was performed.

Results

Upon cerulein induction, SPARC expression was robustly induced in pancreatic stellate cells (PSCs) but not in acinar cells. Genetic SPARC ablation resulted in attenuated severity of AP with significantly reduced levels of pancreatic necrosis, apoptosis, immune cell infiltration, and reduced fibrosis upon chronic stimulation. However, the release of amylase upon cerulein stimulation in primary acinar cell culture from SPARC^+/+ and SPARC^−/− was indistinguishable. Notably, immune cell derived C‐C Motif Chemokine Ligand 2 (CCL2) was highly elevated in SPARC^+/+ pancreatic tissue potentially linking PSC derived SPARC with CCL2 induction in AP.

Conclusion

SPARC mediates the severity of AP. The potential link between SPARC and the CCL2 axis could open new avenues for tailored therapeutic interventions in AP patients and warrants further investigations.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

A new era: tumor microenvironment in chemoresistance of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a solid malignant tumor with an extremely poor prognosis. Gemcitabine (GEM)-based chemotherapy remains one of the most important treatment choices for PDAC. However, either as monotherapy or as a part of the combination chemotherapy, GEM achieved only limited success in improving the survival of patients with advanced PDAC, primarily due to GEM resistance. PDAC is characterized by an extensive desmoplasia in the tumor microenvironment (TME). Increasing evidence indicates that this fibrotic TME not only actively participates in the tumor growth and spread of PDAC but also contributes to the induction of GEM resistance. Here we review the current advances of how TME components are involved in the induction of GEM resistance.

Diverse and precision therapies open new horizons for patients with advanced pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a common cause of cancer-related death, and most patients are with advanced disease when diagnosed. At present, despite a variety of treatments have been developed for PDAC, few effective treatment options are available; on the other hand, PDAC shows significant resistance to chemoradiotherapy, targeted therapy, and immunotherapy due to its heterogeneous genetic profile, molecular signaling pathways, and complex tumor immune microenvironment. Nevertheless, over the past decades, there have been many new advances in the key theory and understanding of the intrinsic mechanisms and complexity of molecular biology and molecular immunology in pancreatic cancer, based on which more and more diverse new means and reasonable combination strategies for PDAC treatment have been developed and preliminary breakthroughs have been made. With the continuous exploration, from surgical local treatment to comprehensive medical management, the research-diagnosis-management system of pancreatic cancer is improving. This review focused on the variety of treatments for advanced PDAC, including traditional chemotherapy, targeted therapy, immunotherapy, microenvironment matrix regulation as well as the treatment targeting epigenetics, metabolism and cancer stem cells. We pointed out the current research bottlenecks and future exploration directions.

Cancer-Associated Fibroblasts and Tumor Cells in Pancreatic Cancer Microenvironment and Metastasis: Paracrine Regulators, Reciprocation and Exosomes

Simple Summary

Cancer-associated fibroblasts in the stromal tumor microenvironment play a key role in cancer progression, invasion, metastasis, and therapy resistance. Cancer-associated fibroblasts communicate with tumor cells through diverse factors, such as growth factors, hedgehog proteins, cytokines, and chemokines, regulating signaling activity in paracrine as well as paracrine-reciprocal ways. Furthermore, cancer-associated fibroblasts, not only tumor cells, secrete exosomes that drive pre-metastatic niche formation and metastasis.

Abstract

Pancreatic cancer is currently the fourth leading cause of cancer deaths in the United States, and the overall 5 year survival rate is still only around 10%. Pancreatic cancer exhibits a remarkable resistance to established therapeutic options such as chemotherapy and radiotherapy, in part due to the dense stromal tumor microenvironment, where cancer-associated fibroblasts are the major stromal cell type. Cancer-associated fibroblasts further play a key role in cancer progression, invasion, and metastasis. Cancer-associated fibroblasts communicate with tumor cells, not only through paracrine as well as paracrine-reciprocal signaling regulators but also by way of exosomes. In the current manuscript, we discuss intercellular mediators between cancer-associated fibroblasts and pancreatic cancer cells in a paracrine as well as paracrine-reciprocal manner. Further recent findings on exosomes in pancreatic cancer and metastasis are summarized.

HIF-1 and NRF2; Key Molecules for Malignant Phenotypes of Pancreatic Cancer

Simple Summary

Pancreatic cancer progression involves interactions between cancer cells and stromal cells in harsh tumor microenvironments, which are characterized by hypoxia, few nutrients, and oxidative stress. Clinically, cancer cells overcome therapeutic interventions, such as chemotherapy and radiotherapy, to continue to survive. Activation of the adaptation mechanism is required for cancer cell survival under these conditions, and it also contributes to the acquisition of the malignant phenotype. Stromal cells, especially pancreatic stellate cells, play a critical role in the formation of a cancer-promoting microenvironment. We here review the roles of key molecules, hypoxia inducible factor-1 and KEAP1-NRF2, in stress response mechanisms for the adaptation to hypoxia and oxidative stress in pancreatic cancer cells and stellate cells. Various cancer-promoting properties associated with these molecules have been identified, and they might serve as novel therapeutic targets in the future.

Abstract

Pancreatic cancer is intractable due to early progression and resistance to conventional therapy. Dense fibrotic stroma, known as desmoplasia, is a characteristic feature of pancreatic cancer, and develops through the interactions between pancreatic cancer cells and stromal cells, including pancreatic stellate cells. Dense stroma forms harsh tumor microenvironments characterized by hypoxia, few nutrients, and oxidative stress. Pancreatic cancer cells as well as pancreatic stellate cells survive in the harsh microenvironments through the altered expression of signaling molecules, transporters, and metabolic enzymes governed by various stress response mechanisms. Hypoxia inducible factor-1 and KEAP1-NRF2, stress response mechanisms for hypoxia and oxidative stress, respectively, contribute to the aggressive behaviors of pancreatic cancer. These key molecules for stress response mechanisms are activated, both in pancreatic cancer cells and in pancreatic stellate cells. Both factors are involved in the mutual activation of cancer cells and stellate cells, by inducing cancer-promoting signals and their mediators. Therapeutic interventions targeting these pathways are promising approaches for novel therapies. In this review, we summarize the roles of stress response mechanisms, focusing on hypoxia inducible factor-1 and KEAP1-NRF2, in pancreatic cancer. In addition, we discuss the potential of targeting these molecules for the treatment of pancreatic cancer.

Emerging agents for metastatic pancreatic cancer: spotlight on early phase clinical trials

INTRODUCTION

Despite the recent development of new chemotherapeutic regimens and combination strategies, metastatic pancreatic cancer (mPC) still shows only a modest response to conventional cytotoxic agents. However, several novel therapeutic agents targeting the unique features of mPC are showing promise in clinical trials.

AREA COVERED

This article reviews the current state of development of new agents targeting various systems and molecular pathways. We searched PubMed and clinicaltrials.gov in September 2021 with a special focus on ongoing early phase clinical trials to identify the promising therapeutic strategies for mPC.

EXPERT OPINION

Extensive tumor heterogeneity, complex tumor microenvironment, genetic alterations of the oncogenic signaling pathways, metabolic dysregulation, and a low immunogenicity are hurdles for current treatment approaches. Ongoing research efforts strive to overcome these hurdles and are showing some promising early results.

Atractylenolide-I Sensitizes Triple-Negative Breast Cancer Cells to Paclitaxel by Blocking CTGF Expression and Fibroblast Activation

This investigation was conducted to elucidate whether atractylenolide-I (ATL-1), which is the main component of Atractylodes macrocephala Koidz, can sensitize triple-negative breast cancer (TNBC) cells to paclitaxel and investigate the possible mechanism involved. We discovered that ATL-1 could inhibit tumor cell migration and increase the sensitivity of tumor cells to paclitaxel. ATL-1 downregulated the expression and secretion of CTGF in TNBC cells. Apart from inhibiting TNBC cell migration via CTGF, ATL-1 downregulated the expression of CTGF in fibroblasts and decreased the ability of breast cancer cells to transform fibroblasts into cancer-associated fibroblasts (CAFs), which in turn increased the sensitivity of TNBC cells to paclitaxel. In a mouse model, we found that ATL-1 treatments could enhance the chemotherapeutic effect of paclitaxel on tumors and reduce tumor metastasis to the lungs and liver. Primary cultured fibroblasts derived from inoculated tumors in mice treated with ATL-1 combined with paclitaxel expressed relatively low levels of CAF markers. Collectively, our data indicate that ATL-1 can sensitize TNBC cells to paclitaxel by blocking CTGF expression and fibroblast activation and could be helpful in future research to determine the value of ATL-1 in the clinical setting.

Matrix stiffness drives stromal autophagy and promotes formation of a protumorigenic niche

Increased stiffness of solid tissues has long been recognized as a diagnostic feature of several pathologies, most notably malignant diseases. In fact, it is now well established that elevated tissue rigidity enhances disease progression and aggressiveness and is associated with a poor prognosis in patients as documented, for instance, for lung fibrosis or the highly desmoplastic cancer of the pancreas. The underlying mechanisms of the interplay between physical properties and cellular behavior are, however, not very well understood. Here, we have found that switching culture conditions from soft to stiff substrates is sufficient to evoke (macro) autophagy in various fibroblast types. Mechanistically, this is brought about by stiffness-sensing through an Integrin αV-focal adhesion kinase module resulting in sequestration and posttranslational stabilization of the metabolic master regulator AMPKα at focal adhesions, leading to the subsequent induction of autophagy. Importantly, stiffness-induced autophagy in stromal cells such as fibroblasts and stellate cells critically supports growth of adjacent cancer cells in vitro and in vivo. This process is Integrin αV dependent, opening possibilities for targeting tumor-stroma crosstalk. Our data thus reveal that the mere change in mechanical tissue properties is sufficient to metabolically reprogram stromal cell populations, generating a tumor-supportive metabolic niche.

T Cell-Mediated Antitumor Immunity Cooperatively Induced By TGFβR1 Antagonism and Gemcitabine Counteracts Reformation of the Stromal Barrier in Pancreatic Cancer

The desmoplastic stroma of pancreatic cancers forms a physical barrier that impedes intratumoral drug delivery. Attempts to modulate the desmoplastic stroma to increase delivery of administered chemotherapy have not shown positive clinical results thus far, and preclinical reports in which chemotherapeutic drugs were coadministered with antistromal therapies did not universally demonstrate increased genotoxicity despite increased intratumoral drug levels. In this study, we tested whether TGFβ antagonism can break the stromal barrier, enhance perfusion and tumoral drug delivery, and interrogated cellular and molecular mechanisms by which the tumor prevents synergism with coadministered gemcitabine. TGFβ inhibition in genetically engineered murine models (GEMM) of pancreas cancer enhanced tumoral perfusion and increased intratumoral gemcitabine levels. However, tumors rapidly adapted to TGFβ-dependent stromal modulation, and intratumoral perfusion returned to pre-treatment levels upon extended TGFβ inhibition. Perfusion was governed by the phenotypic identity and distribution of cancer-associated fibroblasts (CAF) with the myelofibroblastic phenotype (myCAFs), and myCAFs which harbored unique genomic signatures rapidly escaped the restricting effects of TGFβ inhibition. Despite the reformation of the stromal barrier and reversal of initially increased intratumoral exposure levels, TGFβ inhibition in cooperation with gemcitabine effectively suppressed tumor growth via cooperative reprogramming of T regulatory cells and stimulation of CD8 T cell-mediated antitumor activity. The antitumor activity was further improved by the addition of anti-PD-L1 immune checkpoint blockade to offset adaptive PD-L1 upregulation induced by TGFβ inhibition. These findings support the development of combined antistroma anticancer therapies capable of impacting the tumor beyond the disruption of the desmoplastic stroma as a physical barrier to improve drug delivery.

Tumor microenvironment and metabolic remodeling in gemcitabine-based chemoresistance of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a solid malignant tumor with a very low operative rate and a poor patient prognosis. Therefore, gemcitabine (GEM)-based chemotherapy remains one of the most important treatment choices for PDAC. However, the efficacy of GEM monotherapy or GEM combination chemotherapy in improving the survival of patients with advanced PDAC is very limited, primarily due to GEM resistance. The mechanism of GEM resistance is complex and unclear. An extensive and dense fibrous matrix in the tumor microenvironment (TME) is an important feature of PDAC. Increasing evidence indicates that this fibrotic TME not only actively participates in the growth and spread of PDAC but also contributes to the induction of GEM resistance. Metabolic remodeling reduces GEM transport and synthesis in PDAC. This review focuses on the main cellular and molecular mechanisms underlying the involvement of the extracellular matrix (ECM), immune cells, and metabolic remodeling in the induction of GEM resistance; highlights the prospect of targeting the TME as an essential strategy to overcome GEM resistance; and provides new precise interventions for chemotherapy sensitization and improving the overall prognosis of patients with PDAC.

Targeting REG3β limits pancreatic ductal adenocarcinoma progression through CTGF downregulation

The crosstalk between the transformed tumoral cells and their microenvironment is a key aspect for pancreatic ductal adenocarcinoma (PDAC) progression. This molecular dialog is intensively studied because it may result in an efficient therapeutic target. Contrary to this near microenvironment, the stromal portion in direct contact with the transformed cells, a far microenvironment, placed at the periphery of the tumor mass, produces factors signaling tumors. Among these factors, REG3β, produced by this part of the pancreas, is an important factor in promoting tumor progression. This paper demonstrated that targeting REG3β protein with specific antibodies limits the PDAC tumor growth in an orthotopic, syngeneic mice model induced by injection of Panc02 cells. Then, we showed that CTGF is over-expressed in response to REG3β in PDAC-derived cells. Moreover, inactivation of REG3β by treating tumors with anti-REG3β antibodies results in a strong decrease of CTGF in PDAC tumors. Lastly, we demonstrated that forced expression of CTGF in xenografted Panc02 cells abolishes the therapeutic effect of the anti-REG3β antibody treatment. Altogether, these results indicate that the effect of REG3β in promoting PDAC progression is mediated by CTGF over-activation. Thus, REG3β is a promising therapeutic target to treat PDAC with an original rationale. In conclusion, we demonstrated that the far microenvironment is essential for PDAC progression by producing active secretory factors, and some of them could be used as therapeutic targets.

Emerging roles for the YAP/TAZ transcriptional regulators in brain tumour pathology and targeting options

The transcriptional co-activators Yes-associated protein 1/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) have emerged as significant regulators of a wide variety of cellular and organ functions with impact in early embryonic development, especially during the expansion of the neural progenitor cell pool. YAP/TAZ signalling regulates organ size development, tissue homeostasis, wound healing and angiogenesis by participating in a complex network of various pathways. However, recent evidence suggests an association of these physiologic regulatory effects of YAP/TAZ with pro-oncogenic activities. Herein, we discuss the physiological functions of YAP/TAZ as well as the extensive network of signalling pathways that control their expression and activity, leading to brain tumour development and progression. Furthermore, we describe current targeting approaches and drug options including direct YAP/TAZ and YAP-TEA domain transcription factor (TEAD) interaction inhibitors, G-protein coupled receptors (GPCR) signalling modulators and kinase inhibitors, which may be used to successfully attack YAP/TAZ-dependent tumours.

Biological Significance of YAP/TAZ in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal types of cancer. Despite major advances in defining the molecular mutations driving PDAC, this disease remains universally lethal with an overall 5-year survival rate of only about 7–8%. Genetic alterations in PDAC are exemplified by four critical genes (KRAS, TP53, CDKN2A, and SMAD4) that are frequently mutated. Among these, KRAS mutation ranges from 88% to 100% in several studies. Hippo signaling is an evolutionarily conserved network that plays a key role in normal organ development and tissue regeneration. Its core consists of the serine/threonine kinases mammalian sterile 20-like kinase 1 and 2 (MST1/2) and large tumor suppressor 1 and 2. Interestingly, pancreas-specific MST1/2 double knockout mice have been reported to display a decreased pancreas mass. Many of the genes involved in the Hippo signaling pathway are recognized as tumor suppressors, while the Hippo transducers Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are identified as oncogenes. By dephosphorylation, YAP and TAZ accumulate in the nucleus and interact with transcription factors such as TEA domain transcription factor-1, 2, 3, and 4. Dysregulation of Hippo signaling and activation of YAP/TAZ have been recognized in a variety of human solid cancers, including PDAC. Recent studies have elucidated that YAP/TAZ play a crucial role in the induction of acinar-to-ductal metaplasia, an initial step in the progression to PDAC, in genetically engineered mouse models. YAP and TAZ also play a key role in the development of PDAC by both KRAS-dependent and KRAS-independent bypass mechanisms. YAP/TAZ have become extensively studied in PDAC and their biological importance during the development and progression of PDAC has been uncovered. In this review, we summarize the biological significance of a dysregulated Hippo signaling pathway or activated YAP/TAZ in PDAC and propose a role for YAP/TAZ as a therapeutic target.

Gemcitabine/nab-paclitaxel with pamrevlumab: a novel drug combination and trial design for the treatment of locally advanced pancreatic cancer

Purpose

Pancreatic ductal adenocarcinomas exhibit a high degree of desmoplasia due to extensive extracellular matrix deposition. Encasement of mesenteric vessels by stroma in locally advanced pancreatic cancer (LAPC) prevents surgical resection. This study sought to determine if the addition of a monoclonal antibody to connective tissue growth factor, pamrevlumab, to neoadjuvant chemotherapy would be safe and lead to improved resectability in this surgically adverse patient population.

Methods

In this phase I/II trial, 37 patients with LAPC were randomised 2:1 to gemcitabine/nab-paclitaxel plus (Arm A, n=24) or minus (Arm B, n=13) pamrevlumab. Those who completed six cycles of treatment were assessed for surgical eligibility by protocol-defined criteria. Resection rates, progression-free and overall survival were evaluated.

Results

Eighteen (75%) patients in Arm A and seven (54%) in Arm B completed six cycles of therapy with similar toxicity patterns. In Arms A and B, carbohydrate antigen 19–9 response, as defined by ≥50% decline from baseline, occurred in 13 (65%) and 5 (42%), respectively. Sixteen (16%) per cent of patients were radiographically downstaged by National Comprehensive Cancer Network criteria (5 in Arm A (21%) and 1 (8%) in Arm B). Positron emission tomography normalised in 9 (38%) vs 3 (23%) of patients in Arm A vs Arm B, respectively, and correlated with surgical exploration. Eligibility for surgical exploration was 17 (71%) vs 2 (15%) (p=0.0019) and resection was achieved in 8 (33%) vs 1 (8%) of patients in Arm A vs Arm B (p=0.1193), respectively. Postoperative complication rates were not different between arms.

Conclusions

Neoadjuvant chemotherapy with pamrevlumab holds promise for enhancing resection rates in patients with LAPC without added toxicity. This combination merits evaluation in a larger patient cohort.

Targeting the Stroma in the Management of Pancreatic Cancer

Pancreatic cancer (PC) presents extremely aggressive tumours and is associated with poor survival. This is attributed to the unique features of the tumour microenvironment (TME), which is known to create a dense stromal formation and poorly immunogenic condition. In particular, the TME of PC, including the stromal cells and extracellular matrix, plays an essential role in the progression and chemoresistance of PC. Consequently, several promising agents that target key components of the stroma have already been developed and are currently in multiple stages of clinical trials. Therefore, the authors review the latest available evidence on novel stroma-targeting approaches, highlighting the potential impact of the stroma as a key component of the TME in PC.