The Hepatic Microenvironment and TRAIL-R2 Impact Outgrowth of Liver Metastases in Pancreatic Cancer after Surgical Resection

Awakening of Dormant Breast Cancer Cells in the Bone Marrow

Up to 40% of patients with breast cancer (BC) have metastatic cells in the bone marrow (BM) at the initial diagnosis of localized disease. Despite definitive systemic adjuvant therapy, these cells survive in the BM microenvironment, enter a dormant state and recur stochastically for more than 20 years. Once they begin to proliferate, recurrent macrometastases are not curable, and patients generally succumb to their disease. Many potential mechanisms for initiating recurrence have been proposed, but no definitive predictive data have been generated. This manuscript reviews the proposed mechanisms that maintain BC cell dormancy in the BM microenvironment and discusses the data supporting specific mechanisms for recurrence. It addresses the well-described mechanisms of secretory senescence, inflammation, aging, adipogenic BM conversion, autophagy, systemic effects of trauma and surgery, sympathetic signaling, transient angiogenic bursts, hypercoagulable states, osteoclast activation, and epigenetic modifications of dormant cells. This review addresses proposed approaches for either eliminating micrometastases or maintaining a dormant state.

Serum-Free Production of Human Stem Cell-Derived Liver Spheres for Cancer Metastasis Research

Renewable and scalable human liver tissue platforms are a powerful tool to study organ physiology and model diseases, such as cancer. Stem cell-derived models provide an alternative to cell lines, which can display limited relevance to primary cells and tissue. Historically, two-dimensional (2D) cultures have been used to model liver biology as they are easy to scale and deploy. However, 2D liver models lack functional diversity and phenotypic stability in long-term culture. To address those issues, protocols for generating the three-dimensional (3D) tissue aggregates have been developed. Here, we describe a methodology to generate 3D liver spheres from pluripotent stem cells. Liver spheres are composed of three key liver cell types (hepatic progenitor cells, endothelial cells, and hepatic stellate cells) and have been used to study human cancer cell metastasis.

C-Reactive Protein as Predictor for Infectious Complications after Robotic and Open Esophagectomies

Introduction: The value of C-reactive protein (CRP) as a predictor of anastomotic leakage (AL) after esophagectomy has been addressed by numerous studies. Despite its increasing application, robotic esophagectomy (RAMIE) has not been considered separately yet in this context. We, therefore, aimed to evaluate the predictive value of CRP in RAMIE. Material and Methods: Patients undergoing RAMIE or completely open esophagectomy (OE) at our University Center were included. Clinical data, CRP- and Procalcitonin (PCT)-values were retrieved from a prospectively maintained database and evaluated for their predictive value for subsequent postoperative infectious complications (PIC) (AL, gastric conduit leakage or necrosis, pneumonia, empyema). Results: Three hundred and five patients (RAMIE: 160, OE: 145) were analyzed. PIC were noted in 91 patients on postoperative day (POD) 10 and 123 patients on POD 30, respectively. Median POD of diagnosis of PIC was POD 8. Post-operative CRP-values in the robotic-group peaked one and two days later, respectively, and converged from POD 5 onward compared to the open-group. In the group with PIC, CRP-levels in the robotic-group were initially lower and started to differ significantly from POD 3 onward. In the open-group, increases were already noticed from POD 3 on. Procalcitonin levels did not differ. Best Receiver operating curve (ROC)-results were on POD 4, highest negative predictive values at POD 5 (RAMIE) and POD 4 (OE) with cut-off values of 70 mg/L and 88.3 mg/L, respectively. Conclusion: Post-operative CRP is a good negative predictor for PIC, after both RAMIE and OE. After RAMIE, CRP peaks later with a lower cut-off value.

Biomarkers in Liquid Biopsies for Prediction of Early Liver Metastases in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid malignancies with poor survival rates. Only 20% of the patients are eligible for R0-surgical resection, presenting with early relapses, mainly in the liver. PDAC patients with hepatic metastases have a worse outcome compared to patients with metastases at other sites. Early detection of hepatic spread bears the potential to improve patient outcomes. Thus, this study sought for serum-based perioperative biomarkers allowing discrimination of early (EHMS ≤ 12 months) and late hepatic metastatic spread (LHMS > 12 months). Serum samples from 83 resectable PDAC patients were divided into EHMS and LHMS and analyzed for levels of inflammatory mediators by LEGENDplexTM, which was validated and extended by Olink® analysis. CA19-9 serum levels served as control. Results were correlated with clinicopathological data. While serum CA19-9 levels were comparable, Olink® analysis confirmed distinct differences between both groups. It revealed significantly elevated levels of factors involved in chemotaxis and migration of immune cells, immune activity, and cell growth in serum of LHMS-patients. Overall, Olink® analysis identified a comprehensive biomarker panel in serum of PDAC patients that could provide the basis for predicting LHMS. However, further studies with larger cohorts are required for its clinical translation.

Thorny ground, rocky soil: Tissue-specific mechanisms of tumor dormancy and relapse

Disseminated tumor cells (DTCs) spread systemically yet distinct patterns of metastasis indicate a range of tissue susceptibility to metastatic colonization. Distinctions between permissive and suppressive tissues are still being elucidated at cellular and molecular levels. Although there is a growing appreciation for the role of the microenvironment in regulating metastatic success, we have a limited understanding of how diverse tissues regulate DTC dormancy, the state of reversible quiescence and subsequent awakening thought to contribute to delayed relapse. Several themes of microenvironmental regulation of dormancy are beginning to emerge, including vascular association, co-option of pre-existing niches, metabolic adaptation, and immune evasion, with tissue-specific nuances. Conversely, DTC awakening is often associated with injury or inflammation-induced activation of the stroma, promoting a proliferative environment with DTCs following suit. We review what is known about tissue-specific regulation of tumor dormancy on a tissue-by-tissue basis, profiling major metastatic organs including the bone, lung, brain, liver, and lymph node. An aerial view of the barriers to metastatic growth may reveal common targets and dependencies to inform the therapeutic prevention of relapse.

The Heterogeneity of the Tumor Microenvironment as Essential Determinant of Development, Progression and Therapy Response of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is commonly diagnosed at advanced stages and most anti-cancer therapies have failed to substantially improve prognosis of PDAC patients. As a result, PDAC is still one of the deadliest tumors. Tumor heterogeneity, manifesting at multiple levels, provides a conclusive explanation for divergent survival times and therapy responses of PDAC patients. Besides tumor cell heterogeneity, PDAC is characterized by a pronounced inflammatory stroma comprising various non-neoplastic cells such as myofibroblasts, endothelial cells and different leukocyte populations which enrich in the tumor microenvironment (TME) during pancreatic tumorigenesis. Thus, the stromal compartment also displays a high temporal and spatial heterogeneity accounting for diverse effects on the development, progression and therapy responses of PDAC. Adding to this heterogeneity and the impact of the TME, the microbiome of PDAC patients is considerably altered. Understanding this multi-level heterogeneity and considering it for the development of novel therapeutic concepts might finally improve the dismal situation of PDAC patients. Here, we outline the current knowledge on PDAC cell heterogeneity focusing on different stromal cell populations and outline their impact on PDAC progression and therapy resistance. Based on this information, we propose some novel concepts for treatment of PDAC patients.

Regulation of Cancer Metastasis by TRAIL/Death Receptor Signaling

Death ligands such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL; TNFSF10) and their corresponding death receptors (e.g., DR5) not only initiate apoptosis through activation of the extrinsic apoptotic pathway but also exert non-apoptotic biological functions such as regulation of inflammation and cancer metastasis. The involvement of the TRAIL/death receptor signaling pathway in the regulation of cancer invasion and metastasis is complex as both positive and negative roles have been reported. The underlying molecular mechanisms are even more complicated. This review will focus on discussing current knowledge in our understanding of the involvement of TRAIL/death receptor-mediated signaling in the regulation of cancer cell invasion and metastasis.

Steps in metastasis: an updated review

Metastasis is the most complex and deadly event. Tumor-stromal interface is a place where invasion of tumor cells in the form of single-cell or collective migration occurs, with the latter being less common but more efficient. Initiation of metastasis relies on the tumor cell cross-talking with stromal cells and taking an epithelial-mesenchymal transition (EMT) in single cells, and a hybrid EMT in collective migratory cells. Stromal cross-talking along with an abnormal leaky vasculature facilitate intravasation of tumor cells, here the cells are called circulating tumor cells (CTCs). Tumor cells isolated from the primary tumor exploit several mechanisms to maintain their survival including rewiring metabolic demands to use sources available within the new environments, avoiding anoikis cell death when cells are detached from extracellular matrix (ECM), adopting flow mechanic by acquiring platelet shielding and immunosuppression by negating the activity of suppressor immune cells, such as natural killer (NK) cells. CTCs will adhere to the interstituim of the secondary organ/s, within which the newly arrived disseminative tumor cells (DTCs) undergo either dormancy or proliferation. Metastatic outgrowth is under the influence of several factors, such as the activity of macrophages, impaired autophagy and secondary site inflammatory events. Metastasis can be targeted by multiple ways, such as repressing the promoters of pre-metastatic niche (PMN) formation, suppressing environmental contributors, such as hypoxia, oxidative and metabolic stressors, and targeting signaling and cell types that take major contribution to the whole process. These strategies can be used in adjuvant with other therapeutics, such as immunotherapy.

Development of a cost-effective automated platform to produce human liver spheroids for basic and applied research

Liver disease represents an increasing cause of global morbidity and mortality. Currently, liver transplant is the only treatment curative for end-stage liver disease. Donor organs cannot meet the demand and therefore scalable treatments and new disease models are required to improve clinical intervention. Pluripotent stem cells represent a renewable source of human tissue. Recent advances in three-dimensional cell culture have provided the field with more complex systems that better mimic liver physiology and function. Despite these improvements, current cell-based models are variable in performance and expensive to manufacture at scale. This is due, in part, to the use of poorly defined or cross-species materials within the process, severely affecting technology translation. To address this issue, we have developed an automated and economical platform to produce liver tissue at scale for modelling disease and small molecule screening. Stem cell derived liver spheres were formed by combining hepatic progenitors with endothelial cells and stellate cells, in the ratios found within the liver. The resulting tissue permitted the study of human liver biology 'in the dish' and could be scaled for screening. In summary, we have developed an automated differentiation system that permits reliable self-assembly of human liver tissue for biomedical application. Going forward we believe that this technology will not only serve as anin vitroresource, and may have an important role to play in supporting failing liver function in humans.

The current paradigm and challenges ahead for the dormancy of disseminated tumor cells

Disseminated tumor cells (DTCs) are known to enter a state of dormancy that is achieved via growth arrest of DTCs and/or a form of population equilibrium state, strongly influenced by the organ microenvironment. During this time, expansion of residual disseminated cancer is paused and DTCs survive to fuel relapse, sometimes decades later. This notion has opened a new window of opportunity for intervening and preventing relapse. Here we review recent data that have further augmented the understanding of cancer dormancy and discuss how this is leading to new strategies for monitoring and targeting dormant cancer.

Oncolytic Adenovirus Expressing ST13 Increases Antitumor Effect of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Against Pancreatic Ductal Adenocarcinoma

Oncolytic adenoviruses (OAds) are promising agents for cancer therapy, representing a novel therapeutic strategy for pancreatic ductal adenocarcinoma (PDAC). However, there are challenges associated with the successful use of an OAd alone, involving the security of the viral vector and screening of an effective antitumor gene. In the present study, a novel OAd CD55-ST13-tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was constructed in which the dual therapeutic genes ST13 and TRAIL were inserted, featuring the carcinoembryonic antigen (CEA) as a promoter to control E1A and deletion of the 55 kDa E1B gene. ST13, known as a colorectal cancer suppressor gene, exhibited lower expression in PDAC than in tumor-adjacent tissues and was associated with poor prognosis in PDAC patients. In vitro studies demonstrated that CD55-ST13-TRAIL was effective in promoting the expression of ST13 and TRAIL in CEA-positive pancreatic cancer cells. Moreover, CD55-ST13-TRAIL exhibited a synergistic effect toward tumor cell death compared with CD55-ST13 alone or CD55-TRAIL alone, and inhibited tumor cell proliferation and induced cell apoptosis dependent on caspase pathways in PDAC cells. Furthermore, xenograft experiments in a mouse model indicated that CD55-ST13-TRAIL significantly inhibited tumor growth and improved the survival of animals with xenografts. The findings demonstrate that oncolytic virotherapy under the control of the promoter CEA enables safe and efficient treatment of PDAC, and suggest that it represents a promising candidate for the treatment of metastatic diseases.