Complex In Pancreatic Cancer Research Articles

Insights into the Precision Medicine of Pancreatic Cancer: Single-Cell Analysis

The rising incidence of pancreatic cancer (PC) is a global challenge of paramount importance. Understanding the complex nature of this disease is crucial for addressing various issues within the field, including early recurrence, metastasis, and the formidable resistance to chemotherapy and radiotherapy. The complexity of PC arises from the diverse biological phenotypes present in tumor cells, creating a mosaic-like diversity. The lack of comprehensive insights into the functional aspects of cellular and molecular components further complicates treatment, leading to suboptimal outcomes. To tackle these intricacies, researchers must explore the cellular and molecular foundations of this multifaceted disease. Profiling cellular transcriptomes becomes a powerful tool for understanding the subtle heterogeneity in complex cellular populations within tissues. This approach allows for the deconstruction of molecular processes at the individual cell level, revolutionizing our understanding of cellular identity and function. By carefully examining differences in single-cell genomes, transcriptomes, and epigenetic profiles among tumor cells, both primary and metastatic, collected from patient samples, we gain insights into the diverse landscape of tumor heterogeneity. This perspective has significant implications for precision oncology in the context of pancreatic cancer. The current study provides a comprehensive assessment of the empirical basis for RNA sequencing technologies, the methodologies for single-cell isolation, and the conceptual framework for integrating these elements into prognostic assessment, genomic accessibility, transcriptional dynamics, and proteomic landscapes. By combining these components, the study aims to establish a coherent framework that facilitates the development of precision medicine approaches tailored to the unique challenges presented by pancreatic cancer.

Synergistic effect of antagonists to KRas4B/PDE6 molecular complex in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis among all human cancers as it is highly resistant to chemotherapy. K-Ras mutations usually trigger the development and progression of PDAC. We hypothesized that compounds stabilizing the KRas4B/PDE6δ complex could serve as PDAC treatments. Using in silico approaches, we identified the small molecules C14 and P8 that reduced K-Ras activation in primary PDAC cells. Importantly, C14 and P8 significantly prevented tumor growth in patient-derived xenotransplants. Combined treatment with C14 and P8 strongly increased cytotoxicity in PDAC cell lines and primary cultures and showed strong synergistic antineoplastic effects in preclinical murine PDAC models that were superior to conventional therapeutics without causing side effects. Mechanistically, C14 and P8 reduced tumor growth by inhibiting AKT and ERK signaling downstream of K-RAS leading to apoptosis, specifically in PDAC cells. Thus, combined treatment with C14 and P8 may be a superior pharmaceutical strategy to improve the outcome of PDAC.

Histone acetyltransferase 1 promotes gemcitabine resistance by regulating the PVT1/EZH2 complex in pancreatic cancer

The poor prognosis of pancreatic cancer is primarily due to the development of resistance to therapies, including gemcitabine. The long noncoding RNA PVT1 (lncRNA PVT1) has been shown to interact with enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), promoting gemcitabine resistance in pancreatic cancer. In this study, we found histone acetyltransferase 1 (HAT1) enhanced the tolerance of pancreatic cancer cells to gemcitabine and HAT1-mediated resistance mechanisms were regulated by PVT1 and EZH2. Our results showed that the aberrant HAT1 expression promoted gemcitabine resistance, while silencing HAT1 restored gemcitabine sensitivity. Moreover, HAT1 depletion caused a notable increase of gemcitabine sensitivity in gemcitabine-resistant pancreatic cancer cell lines. Further research found that HAT1 increased PVT1 expression to induce gemcitabine resistance, which enhanced the binding of bromodomain containing 4 (BRD4) to the PVT1 promoter, thereby promoting PVT1 transcription. Besides, HAT1 prevented EZH2 degradation by interfering with ubiquitin protein ligase E3 component n-recognin 4 (UBR4) binding to the N-terminal domain of EZH2, thus maintaining EZH2 protein stability to elevate the level of EZH2 protein, which also promoted HAT1-mediated gemcitabine resistance. These results suggested that HAT1 induced gemcitabine resistance of pancreatic cancer cells through regulating PVT1/EZH2 complex. Given this, Chitosan (CS)-tripolyphosphate (TPP)-siHAT1 nanoparticles were developed to block HAT1 expression and improve the antitumor effect of gemcitabine. The results showed that CS-TPP-siHAT1 nanoparticles augmented the antitumor effects of gemcitabine in vitro and in vivo. In conclusion, HAT1-targeted therapy can improve observably gemcitabine sensitivity of pancreatic cancer cells. HAT1 is a promising therapeutic target for pancreatic cancer.

Overcoming Adaptive Resistance to KRAS and MEK Inhibitors by Co-targeting mTORC1/2 Complexes in Pancreatic Cancer

SummaryActivating KRAS mutations are found in over 90% of pancreatic ductal adenocarcinomas (PDACs), yet KRAS has remained a difficult target to inhibit pharmacologically. Here, we demonstrate, using several human and mouse models of PDACs, rapid acquisition of tumor resistance in response to targeting KRAS or MEK, associated with integrin-linked kinase (ILK)-mediated increased phosphorylation of the mTORC2 component Rictor, and AKT. Although inhibition of mTORC1/2 results in a compensatory increase in ERK phosphorylation, combinatorial treatment of PDAC cells with either KRAS (G12C) or MEK inhibitors, together with mTORC1/2 inhibitors, results in synergistic cytotoxicity and cell death reflected by inhibition of pERK and pRictor/pAKT and of downstream regulators of protein synthesis and cell survival. Relative to single agents alone, this combination leads to durable inhibition of tumor growth and metastatic progression in vivo and increased survival. We have identified an effective combinatorial treatment strategy using clinically viable inhibitors, which can be applied to PDAC tumors with different KRAS mutations.

The Emerging Roles of ATP-Dependent Chromatin Remodeling Complexes in Pancreatic Cancer.

Pancreatic cancer is an aggressive cancer with low survival rates. Genetic and epigenetic dysregulation has been associated with the initiation and progression of pancreatic tumors. Multiple studies have pointed to the involvement of aberrant chromatin modifications in driving tumor behavior. ATP-dependent chromatin remodeling complexes regulate chromatin structure and have critical roles in stem cell maintenance, development, and cancer. Frequent mutations and chromosomal aberrations in the genes associated with subunits of the ATP-dependent chromatin remodeling complexes have been detected in different cancer types. In this review, we summarize the current literature on the genomic alterations and mechanistic studies of the ATP-dependent chromatin remodeling complexes in pancreatic cancer. Our review is focused on the four main subfamilies: SWItch/sucrose non-fermentable (SWI/SNF), imitation SWI (ISWI), chromodomain-helicase DNA-binding protein (CHD), and INOsitol-requiring mutant 80 (INO80). Finally, we discuss potential novel treatment options that use small molecules to target these complexes.

925 – Neoplastic and Stromal Cell Cross-Talk Promotes a Collagen Signaling Complex in Pancreatic Cancer

925 – Neoplastic and Stromal Cell Cross-Talk Promotes a Collagen Signaling Complex in Pancreatic Cancer

Inhibition of hypoxic response decreases stemness and reduces tumorigenic signaling due to impaired assembly of HIF1 transcription complex in pancreatic cancer

Pancreatic tumors are renowned for their extremely hypoxic centers, resulting in upregulation of a number of hypoxia mediated signaling pathways including cell proliferation, metabolism and cell survival. Previous studies from our laboratory have shown that Minnelide, a water-soluble pro-drug of triptolide (anti-cancer compound), decreases viability of cancer cells in vitro as well as in vivo. However, its mechanism of action remain elusive. In the current study we evaluated the effect of Minnelide, on hypoxia mediated oncogenic signaling as well as stemness in pancreatic cancer. Minnelide has just completed Phase 1 trial against GI cancers and is currently awaiting Phase 2 trials. Our results showed that upon treatment with triptolide, HIF-1α protein accumulated in pancreatic cancer cells even though hypoxic response was decreased in them. Our studies showed even though HIF-1α is accumulated in the treated cells, there was no decrease in HIF-1 binding to hypoxia response elements. However, the HIF-1 transcriptional activity was significantly reduced owing to depletion of co-activator p300 upon treatment with triptolide. Further, treatment with triptolide resulted in a decreased activity of Sp1 and NF-kB the two major oncogenic signaling pathway in pancreatic cancer along with a decreased tumor initiating cell (TIC) population in pancreatic tumor.

Characterization of NFATc1/Smad3 complexes in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes of cancer-related death all over the world. This disease is difficult to treat and patients have an overall 5-year survival rate of less than 5%. Although two drugs, gemcitabine (GEM) and 5-fluorouracil (5-FU) have been shown to improve the survival rate of patients systematically, they do not increase general survival to a clinically acceptable degree. Lack of ideal clinical response of pancreatic cancer patients to chemotherapy is likely to be due to intrinsic and acquired chemoresistance of tumor cells. Various mechanisms of drug resistance have been investigated in pancreatic cancer, including genetic and epigenetic changes in particular genes or signaling pathways. In addition, evidence suggests that microRNAs (miRNAs) play significant roles as key regulators of gene expression in many cellular processes, including drug resistance. Understanding underlying genes and mechanisms of drug resistance in pancreatic cancer is critical to develop new effective treatments for this deadly disease. This review illustrates the genes and miRNAs involved in resistance to gemcitabine in pancreatic cancer.

Characterization of NFATc1/Smad3 complexes in pancreatic cancer

Characterization of NFATc1/Smad3 complexes in pancreatic cancer

Identification and Evaluation in silico and in vitro of Small Molecules in the KRas4B‐PDEδ Molecular Complex in Pancreatic Cancer

Pancreatic cancer (PDAC) is the most lethal of all cancer types, characterized by an average survival of 6 months and a five‐years survival rate of less than 5%. To increase the survival rate of pancreatic cancer patients is necessary to search for improved tumor markers for an earliest diagnosis and new molecular targets for drug development. In most cases, PDAC is initiated by the mutant of GTPase KRas4B, which has been shown to drive pancreatic neoplasia. Furthermore, it has been demonstrated that nearly 95% of PDAC shown mutational activated KRas4B. Certainly, KRas4B protein has been used as a principal target in anticancer drugs development. Therefore, the identification of new organic molecules that recognize the KRas4B‐PDEδ molecular complex is of great interest for its stabilization for avoiding the activation of KRas4B in the cytoplasmic membrane. Thus, the objective of this work is to identify and evaluate new small molecules that stabilize the KRas4B‐PDEδ complex by using docking techniques. First, we constructed a homology model of KRas4B‐PDEδ complex and this revealed a set of exposed non‐conserved residues at the interface, which are considered an important target for ligand identification. Then, we carried out a docking simulation between the extensive database of drug‐like compounds from ENAMINE and the non‐conserved site at the Kras4B‐PDEδ model using a previous reported protocol. The in vitro evaluation of fourteen compounds with high scores from docking showed a significant specific effect in three of them on the viability of pancreatic cancer cell line MIAPaCa‐2 but not in the pancreatic cell line hTERT‐HPNE used as a control. Interestingly, the compounds decreased Ras‐GTP concentration in the cell line MIAPaCa‐2 in more than 50%, indicating a reduced activity. In conclusion, our results open the possibility to develop drugs against to PDCA; however, we need to perform more experiments in order to establish the specific mechanism of action of the compounds developed in this work.Support or Funding InformationThis work was sponsored by the CONACYT and ISSSTE project number: 002.2015 ISSSTE

Laparoscopic pancreatoduodenectomy: How far have we come and where are we headed?

Minimally invasive pancreatoduodenectomy is currently a feasible option in selected patients at high volume centers with available expertise. Although the procedure has been described two decades ago, laparoscopic surgeons have been reluctant to perform it since it is technically demanding. Currently there is no standardized training process for minimally invasive pancreatoduodenectomy and this is required to ensure the safety of the procedure. Even the open pancreatoduodenectomy can be a challenging procedure where the outcome depends much upon the patient volume and surgeon's experience. In the minimally invasive setting, all the current evidence comes from retrospective data with inherent selection bias. Although the proposed benefits have been reported in many series, a randomized trial comparing with the open approach is highly unlikely to happen, given the complexity of pancreatic cancer and patient selection for complex surgery. Rather, in a disease for which cure is an utopian statement, perhaps the ultimate aim of minimally invasive pancreatoduodenectomy can be the improvement in the quality of life. Also further studies are needed to assess the immunologic role affecting the oncologic outcomes in patients undergoing minimally invasive pancreatoduodenectomy. The robotic platforms have got easily accepted since they can overcome some of the limitations of the laparoscopic platforms such as limited range of motion, two dimensional visualization and poor ergonomics. The main limitations of robotic procedures are related to the high costs associated with the system and disposable equipment. Currently evidence is lacking regarding the cost effectiveness of the procedure and also the push from the industry is on rise. All these minimally invasive techniques have a long learning curve and prior extensive experience in hepatopancreatobiliary surgery is mandatory for surgeons embarking on these endeavours.

The Role of Exosomal Cargo in the Regulation of the Biological Complexity of Pancreatic Cancer

Pancreatic cancer is among the deadliest of all human cancers and remains incurable. There is an urgent need for the identification of specific diagnostic and therapeutic biomarkers with hopes that such markers could be targeted in the development of novel therapeutics for better treatment of pancreatic cancer. The concept that extracellular transport can be mediated by vesicular structure especially exosome was brought to the scientific community in the 1980s; however, it was only in the last 10 years that the field of exosome biology has gained momentum. The surge in research interest was supported by the realization that these vesicular structure can participate in several important cellular processes, and in cancer, these small vesicles are emerging to be recognized as powerful modulators of most of the well-known cancer hallmarks. Exosomes serve as important vehicle for delivering cargo containing proteins, lipids, and nucleic acids. They have been shown to mediate intercellular communication between different cell types in the body, and thus affecting the functioning of normal homeostasis as well as the functioning of different pathological conditions. This brief editorial touches upon some of the complex but expanding role of exosomal cargo in mediating the biology of pancreatic cancer. Some perspective is provided as to how the field of pancreatic cancer in the context of exosome is taking shape with the hope to bring forward successful clinical applications of exosome in guiding advancement for the treatment of pancreatic cancer.

Abstract A234: In vivo RNAi screening to identify major players in pancreatic tumor maintenance and growth.

Abstract Pancreatic cancer is one of the leading causes of cancer-related death in the United States and no effective therapeutic options are currently available. The lethality of pancreatic cancer, due to the aggressiveness of the disease and the lack of effective treatment, underscores the urgency for a clinical solution. Nevertheless the multiple failures suffered in clinical trials involving diverse compounds and approaches point to the necessity of a better understanding of the disease, in particular of the molecular and cellular mechanisms underlying tumor development and progression. We aim to identify new therapeutic targets for pancreatic cancer treatment by performing in vivo RNAi screens, either in combination with Gemcitabine treatment to isolate modulators of drug response or without any treatment seeking for genes that play a fundamental role in tumor growth and maintenance. Our model system is a cancer cell line derived from a genetically engineered mouse model that develops spontaneous pancreatic ductal adenocarcinoma (PDAC) after activation of a kras mutant (G12D) allele concomitantly with the deletion of the tumor suppressor p53 specifically in the pancreas. This cell line can be effectively transplanted orthotopically in syngeneic mice and preliminary data suggest that we can represent about 3.000 hairpins out of 10.000 per tumor when injecting 30.000 cells orthotopically in the pancreas in the absence of chemotherapy. Genes with established function in pancreatic cancer like Claudin4 and PDGFR scored as hits in the screening, and about 8 more were selected for further validation. In addition, our data show that the transplanted tumors are partially resistant to Gemcitabine treatment in vivo, despite the in vitro sensitivity, which indicate that the system is suitable for a synthetic lethal screen. We have established a model system suitable for in vivo screening in pancreatic cancer, either with or without chemotherapy. We challenged the complexity of pancreatic cancer by functional screening in order to focus our attention on potential key player of tumor progression with plausible clinical relevance. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A234. Citation Format: Silvia Fenoglio, Yadira Soto-Feliciano, Gregory Hannon, Michael Hemann. In vivo RNAi screening to identify major players in pancreatic tumor maintenance and growth. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A234.

CXCR2 Macromolecular Complex in Pancreatic Cancer: A Potential Therapeutic Target in Tumor Growth

The signaling mediated by the chemokine receptor CXC chemokine receptor 2 (CXCR2) plays an important role in promoting the progression of many cancers, including pancreatic cancer, one of the most lethal human malignancies. CXCR2 possesses a consensus PSD-95/DlgA/ZO-1 (PDZ) motif at its carboxyl termini, which might interact with potential PDZ scaffold/adaptor proteins. We have previously reported that CXCR2 PDZ motif-mediated protein interaction is an important regulator for neutrophil functions. Here, using a series of biochemical assays, we demonstrate that CXCR2 is physically coupled to its downstream effector phospholipase C-β3 (PLC-β3) that is mediated by PDZ scaffold protein Na+/H+ exchange regulatory factor 1 (NHERF1) into a macromolecular signaling complex both in vitro and in pancreatic cancer cells. We also observe that disrupting the CXCR2 complex, by gene delivery or peptide delivery of exogenous CXCR2 C-tail, significantly inhibits the biologic functions of pancreatic cancer cells (i.e., proliferation and invasion) in a PDZ motif-dependent manner. In addition, using a human pancreatic tumor xenograft model, we show that gene delivery of CXCR2 C-tail sequence (containing the PDZ motif) by adeno-associated virus type 2 viral vector potently suppresses human pancreatic tumor growth in immunodeficient mice. In summary, our results suggest the existence of a physical and functional coupling of CXCR2 and PLC-β3 mediated through NHERF1, forming a macromolecular complex that is critical for efficient and specific CXCR2 signaling in pancreatic cancer progression. Disrupting this CXCR2 complex could represent a novel and effective treatment strategy against pancreatic cancer.

The clinical significance of SWI/SNF complex in pancreatic cancer.

149 Background: Chromatin remodeling factors have been the subject of great interest in oncology. However, little is known about their role in pancreatic cancer. The objective of this study is to clarify the clinical significance of SWI/SNF complex, one of the major chromatin remodeling machineries, in patients with pancreatic cancer. Methods: 68 cases with pancreatic cancer who underwent R0, 1 resection were enrolled. Cancer tissues were processed to tissue microarray, then stained immunohistochemically by using antibody of SWI/SNF components; BRM, BRG1, BAF250a, BAF180, and BAF47. The correlation of expression level and clinicopathological outcome including overall survival were analyzed. Results: Expression level of the SWI/SNF components was categorized as low or high according to the median value of Histo score. Statistical analysis revealed that related factors were tumor size, T factor, M factor, lymphatic invasion, and Stage in BRM, histology and Stage in BRG1, tumor size in BAF180, lymphatic invasion in BAF47, respectively. Multivariate Cox propotional hazard analysis showed high-BRM and low-BAF180 expression level were independent predictors of worse survival in patients with pancreatic cancer. The hazard analysis was also examined in the patients treated with adjuvant gemcitabine, indicating that high-BRM, and low-BAF180 were independent prognostic factors for poor survival. Conclusions: These results suggest that the specific cofactors of SWI/SNF chromatin remodeling complex certainly have roles in pancreatic cancer. High-BRM, and low-BAF180 are useful markers for prognosis of pancreatic cancer.

The clinical significance of SWI/SNF complex in pancreatic cancer

Chromatin remodeling factors have been the subject of great interest in oncology. However, little is known about their role in pancreatic cancer. The objective of this study was to clarify the clinical significance of the SWItch/sucrose nonfermentable (SWI/SNF) complex in patients with pancreatic cancer. A total of 68 patients with pancreatic cancer who underwent R0, 1 resection were enrolled. Cancer tissues were processed to tissue microarray, then stained immunohistochemically by using antibody of SWI/SNF components; BRM, BRG1, BAF250a, BAF180 and BAF47. The correlation of expression levels and clinicopathological outcomes were analyzed, followed by the multivariate analysis of prognostic factors for overall survival. The expression levels of the SWI/SNF components were categorized as low or high according to the median value of Histoscore. Statistical analysis revealed that BRM expression was related to tumor size, T factor, M factor, lymphatic invasion and stage BRG1 expression to histology and stage BAF180 expression to tumor size and BAF47 expression to lymphatic invasion, respectively. Multivariate Cox proportional hazard analysis showed that high BRM and low BAF180 expression levels were independent predictors of worse survival in patients with pancreatic cancer. High BRM, and low BAF180 were also independent prognostic factors for poor survival in the subgroup with adjuvant gemcitabine. These results suggest that the specific cofactors of SWI/SNF chromatin remodeling complex certainly have roles in pancreatic cancer. High BRM, and low BAF180 are useful biomarkers for poor prognosis in pancreatic cancer.

Mutant K-Ras increases GSK-3β gene expression via an ETS-p300 transcriptional complex in pancreatic cancer

Glycogen synthase kinase-3 beta (GSK-3β) is overexpressed in a number of human malignancies and has been shown to contribute to tumor cell proliferation and survival. Although regulation of GSK-3β activity has been extensively studied, the mechanisms governing GSK-3β gene expression are still unknown. Using pancreatic cancer as a model, we find that constitutively active Ras signaling increases GSK-3β gene expression via the canonical mitogen-activated protein kinase signaling pathway. Analysis of the mechanism revealed that K-Ras regulates the expression of this kinase through two highly conserved E-twenty six (ETS) binding elements within the proximal region. Furthermore, we demonstrate that mutant K-Ras enhances ETS2 loading onto the promoter, and ETS requires its transcriptional activity to increase GSK-3β gene transcription in pancreatic cancer cells. Lastly, we show that ETS2 cooperates with p300 histone acetyltransferase to remodel chromatin and promote GSK-3β expression. Taken together, these results provide a general mechanism for increased expression of GSK-3β in pancreatic cancer and perhaps other cancers, where Ras signaling is deregulated.

Convergent structural alterations define SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeler as a central tumor suppressive complex in pancreatic cancer

Defining the molecular genetic alterations underlying pancreatic cancer may provide unique therapeutic insight for this deadly disease. Toward this goal, we report here an integrative DNA microarray and sequencing-based analysis of pancreatic cancer genomes. Notable among the alterations newly identified, genomic deletions, mutations, and rearrangements recurrently targeted genes encoding components of the SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeling complex, including all three putative DNA binding subunits (ARID1A, ARID1B, and PBRM1) and both enzymatic subunits (SMARCA2 and SMARCA4). Whereas alterations of each individual SWI/SNF subunit occurred at modest-frequency, as mutational "hills" in the genomic landscape, together they affected at least one-third of all pancreatic cancers, defining SWI/SNF as a major mutational "mountain." Consistent with a tumor-suppressive role, re-expression of SMARCA4 in SMARCA4-deficient pancreatic cancer cell lines reduced cell growth and promoted senescence, whereas its overexpression in a SWI/SNF-intact line had no such effect. In addition, expression profiling analyses revealed that SWI/SNF likely antagonizes Polycomb repressive complex 2, implicating this as one possible mechanism of tumor suppression. Our findings reveal SWI/SNF to be a central tumor suppressive complex in pancreatic cancer.