Metastatic inefficiency: intravascular and intraperitoneal implantation of cancer cells

Can a morphological description of the peritoneal carcinomatosis in advanced ovarian cancer add prognostic information? Analysis of 1686 patients of the tumor bank ovarian cancer

Background

Peritoneal carcinomatosis in ovarian cancer is frequent and generally associated with higher stage and poorer outcome. The clinical features of peritoneal carcinomatosis are diverse and their relevance for surgical and long-term outcome remains unclear. We conducted this prospective study to describe intraoperatively the different features of peritoneal carcinomatosis(PC) and correlate them with clinicopathological features, progression-free(PFS) and overall survival (OS),.

Methods

We performed a systematic analysis of all patients with documented intraoperative PC and a primary diagnosis of epithelial ovarian, tubal, or peritoneal cancer from January 2001 to September 2018. All data were evaluated by using the systematic tumor bank tool. Specific PC features included texture(soft-hard), consistency(coarse-fine or both), wet vs dry(PC with ascites vs. PC without ascites), and localization(diffuse-local). PC characteristics were then evaluated for correlation with age, FIGO-stage, histology, lymph-node involvement, grade, and presence of residual tumor at primary surgery. Moreover, the influence of PC characteristics on OS and PFS was analyzed.

Results

A total of 1686 patients with PC and primary epithelial ovarian cancer were included. Majority of the patients were characterized by diffuse PC(73.9%). The majority of peritoneal nodules were fine in texture (55.3%) and hard in consistency (87.4%). Moreover, 27.6% of patients had dry PC. Diffuse PC localization was significantly associated with higher FIGO-stage (p<0.001), high-grade (p=0.003) and serous tumors (p=0.006) as well as residual tumor as compared to local PC (p<0.001). Wet PC also significantly correlated with diffuse localization (p <0.001) and residual tumor as compared to dry PC (p<0.001). Coarse PC was significantly associated with residual tumor as compared to fine PC (p=0.044). All other PC features didn´t correlate with clinicopathological features. As for survival outcomes, diffuse peritoneal localization (p<0.001), wet PC (p<0.001), and additional lymph node involvement (p<0.001) were associated with lower OS and PFS rates. Other PC features did not significantly impact survival.

Conclusion

Diffuse localization of peritoneal carcinomatosis was significant predictor of recurrence. Lower OS and PFS were associated with diffuse peritoneal localization, wet PC, and additional lymph node involvement. Further prospective trials are warranted with the inclusion of translational research aspects to better understand the different peritoneal carcinomatosis patterns.

Spontaneous and Induced Animal Models for Cancer Research

Considering the complexity of the current framework in oncology, the relevance of animal models in biomedical research is critical in light of the capacity to produce valuable data with clinical translation. The laboratory mouse is the most common animal model used in cancer research due to its high adaptation to different environments, genetic variability, and physiological similarities with humans. Beginning with spontaneous mutations arising in mice colonies that allow for pursuing studies of specific pathological conditions, this area of in vivo research has significantly evolved, now capable of generating humanized mice models encompassing the human immune system in biological correlation with human tumor xenografts. Moreover, the era of genetic engineering, especially of the hijacking CRISPR/Cas9 technique, offers powerful tools in designing and developing various mouse strains. Within this article, we will cover the principal mouse models used in oncology research, beginning with behavioral science of animals vs. humans, and continuing on with genetically engineered mice, microsurgical-induced cancer models, and avatar mouse models for personalized cancer therapy. Moreover, the area of spontaneous large animal models for cancer research will be briefly presented.

Engineering the pre-metastatic niche

The pre-metastatic niche — the accumulation of aberrant immune cells and extracellular matrix proteins in target organs — primes the initially healthy organ microenvironment and renders it amenable for subsequent metastatic cell colonization. By attracting metastatic cancer cells, mimics of the pre-metastatic niche offer both diagnostic and therapeutic potential. However, deconstructing the complexity of the niche by identifying the interactions between cell populations and the mediatory roles of the immune system, soluble factors, extracellular matrix proteins, and stromal cells has proved challenging. Experimental models need to recapitulate niche-population biology in situ and mediate in vivo tumour-cell homing, colonization and proliferation. In this Review, we outline the biology of the pre-metastatic niche and discuss advances in engineered niche-mimicking biomaterials that regulate the behaviour of tumour cells at an implant site. Such oncomaterials offer strategies for early detection of metastatic events, inhibiting the formation of the pre-metastatic niche, and attenuating metastatic progression.

Increased autophagic response in a population of metastatic breast cancer cells

Breast cancer cells are heterogeneous in their ability to invade and fully metastasize, and thus also in their capacity to survive the numerous stresses encountered throughout the multiple steps of the metastatic cascade. Considering the role of autophagy as a survival response to stress, the present study hypothesized that distinct populations of breast cancer cells may possess an altered autophagic capacity that influences their metastatic potential. It was observed that a metastatic breast cancer cell line, MDA-MB-231, that was sensitive to autophagic induction additionally possessed the ability to proliferate following nutrient deprivation. Furthermore, a selected subpopulation of these cells that survived multiple exposures to starvation conditions demonstrated a heightened response to autophagic induction compared to their parent cells. Although this subpopulation maintained a more grape-like pattern in three-dimensional culture compared to the extended spikes of the parent population, autophagic induction in this subpopulation elicited an invasive phenotype with extended spikes. Taken together, these results suggest that autophagic induction may contribute to the ability of distinct breast cancer cell populations to survive and invade.

Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis?

Environmental contributions to cancer development are widely accepted, but only a fraction of all pertinent exposures have probably been identified. Traditional toxicological approaches to the problem have largely focused on the effects of individual agents at singular endpoints. As such, they have incompletely addressed both the pro-carcinogenic contributions of environmentally relevant low-dose chemical mixtures and the fact that exposures can influence multiple cancer-associated endpoints over varying timescales. Of these endpoints, dysregulated metabolism is one of the most common and recognizable features of cancer, but its specific roles in exposure-associated cancer development remain poorly understood. Most studies have focused on discrete aspects of cancer metabolism and have incompletely considered both its dynamic integrated nature and the complex controlling influences of substrate availability, external trophic signals and environmental conditions. Emerging high throughput approaches to environmental risk assessment also do not directly address the metabolic causes or consequences of changes in gene expression. As such, there is a compelling need to establish common or complementary frameworks for further exploration that experimentally and conceptually consider the gestalt of cancer metabolism and its causal relationships to both carcinogenesis and the development of other cancer hallmarks. A literature review to identify environmentally relevant exposures unambiguously linked to both cancer development and dysregulated metabolism suggests major gaps in our understanding of exposure-associated carcinogenesis and metabolic reprogramming. Although limited evidence exists to support primary causal roles for metabolism in carcinogenesis, the universality of altered cancer metabolism underscores its fundamental biological importance, and multiple pleiomorphic, even dichotomous, roles for metabolism in promoting, antagonizing or otherwise enabling the development and selection of cancer are suggested.

Recent insights into the pathophysiology of omental metastases

Although, useful in inflammatory conditions, the greater omentum represents an important site of metastasis in peritoneal carcinomatosis and is therefore frequently removed as a staging or therapeutic tool. Apart from the milky spots, omental adipose stem cells, and adipocytes have recently been identified to play a role in the preferential homing of tumor cells to the omentum. The extent of omentectomy and whether a routine omentectomy should be done are still known unknowns.

Cyto-reductive Surgery combined with Hyperthermic Intra-peritoneal Chemotherapy for Peritoneal Surface Malignancies: current treatment and results

Cyto-reductive Surgery (CS) combined with Hyperthermic Intra-peritoneal Chemotherapy (HIPEC) as loco-regional treatment of Peritoneal Surface Malignancies (PSM) has increasingly gained acceptance in clinical practice. This review summarizes the more relevant studies on this topic. Indications, pre-operative work-up, technical aspects, outcome and future directions of this combined approach in the treatment of Peritoneal Surface Malignancies are discussed here and proposed in an informative and didactic manner.

Cancer stem cells in solid tumors: is 'evading apoptosis' a hallmark of cancer?

Conventional wisdom has long held that once a cancer cell has developed it will inevitably progress to clinical disease. Updating this paradigm, it has more recently become apparent that the tumor interacts with its microenvironment and that some environmental bottlenecks, such as the angiogenic switch, must be overcome for the tumor to progress. In parallel, attraction has been drawn to the concept that there is a minority population of cells - the cancer stem cells - bestowed with the exclusive ability to self-renew and regenerate the tumor. With therapeutic targeting issues at stake, much attention has shifted to the identification of cancer stem cells, the thinking being that the remaining non-stem population, already fated to die, will play a negligible role in tumor development. In fact, the newly appreciated importance of intercellular interactions in cancer development also extends in a unique and unexpected way to interactions between the stem and non-stem compartments of the tumor. Here we discuss recent findings drawn from a hybrid mathematical-cellular automaton model that simulates growth of a heterogeneous solid tumor comprised of cancer stem cells and non-stem cancer cells. The model shows how the introduction of cell fate heterogeneity paradoxically influences the tumor growth dynamic in response to apoptosis, to reveal yet another bottleneck to tumor progression potentially exploitable for disease control.

Prospective cytological assessment of gastrointestinal luminal fluid acquired during EUS: a potential source of false-positive FNA and needle tract seeding

OBJECTIVES

Endoscopic ultrasound (EUS) fine needle aspiration (FNA) can result in false-positive cytology and can also cause needle tract seeding. Our goal was to evaluate a potential cause, namely, the presence of malignant cells within gastrointestinal (GI) luminal fluid, either as a result of tumor sloughing from luminal cancers or secondary to FNA of extraluminal sites.

METHODS

During EUS, luminal fluid that is usually aspirated through the echoendoscope suction channel and discarded was instead submitted for cytological analysis among patients with cancer and benign disease. Pre- and post-FNA luminal fluid samples were collected to discern the role of FNA in inducing a positive cytology. When not performing FNA, one sample was collected for the entire examination. The final diagnosis was based on strict clinicopathological criteria and >or=2-year follow-up. This study was conducted in a tertiary referral center.

RESULTS

We assessed the prevalence of luminal fluid-positive cytology among patients with luminal (e.g., esophageal), extraluminal (e.g., pancreatic), and benign disease. Among the 140 patients prospectively enrolled with sufficient sampling and follow-up, an examination of luminal fluid cytology showed positive results for malignancy in luminal and extraluminal cancer patients, 48 and 10%, respectively. This included 8 out of 23 esophageal, 4 of 5 gastric, and 9 of 15 rectal cancers. The positive luminal fluid cytology rate with luminal cancers was not affected by performing FNA. Post-FNA luminal fluid cytology was positive in 3 out of 26 with pancreatic cancers. Cytological examination of luminal fluid aspirates did not demonstrate malignant cells in any patient with nonmalignant disease.

CONCLUSIONS

Malignant cells are commonly present in the GI luminal fluid of patients with luminal cancers and can also be found in patients with pancreatic cancer after EUS FNA. Further study is needed to determine the impact of these findings on cytological interpretation, staging, risk of needle tract seeding, and patient care and outcomes.

A "class action" against the microenvironment: do cancer cells cooperate in metastasis?

The authors review how cancer cells may cooperate in metastasis by means of microenvironmental changes. The main mechanisms underlying this cooperation are clustered migration of cancer cells, extracellular matrix degradation, paracrine loops of released signaling factors and/or induction of adhesion molecules on stromal cells. Another critical factor could be temporal cooperation: successive waves of cancer cells may induce progressive conditioning of the microenvironment. The "class action" of cancer cells against the microenvironment involves successive steps of the metastatic process: invasion of the primary tumor microenvironment, collective migration through the extracellular matrix, blood vessel disruption, vascular or lymphatic tumor emboli, establishment of a premetastatic niche by secreted factors and endothelial precursor recruitment, induction of cell adhesion molecule expression in endothelial cells, extravasation, micrometastasis dormancy and establishment of a new growth in distant sites. As a result, after completion of the metastatic process, the series of microenvironmental changes from the primary tumor to the metastatic site may promote colonization of metastases by nonmetastatic cancer cells of the primary tumor.

Tumour dormancy in breast cancer: an update

Delayed recurrences, common in breast cancer, are well explained by the concept of tumour dormancy. Numerous publications describe clinical times to disease recurrence or death, using mathematical approaches to infer mechanisms responsible for delayed recurrences. However, most of the clinical literature discussing tumour dormancy uses data from over a half century ago and much has since changed. This review explores how current breast cancer treatment could change our understanding of the biology of breast cancer tumour dormancy, and summarizes relevant experimental models to date. Current knowledge gaps are highlighted and potential areas of future research are identified.

Suppression of salivary adenoid cystic carcinoma growth and metastasis by ErbB3 binding protein Ebp1 gene transfer

Ebp1, an ErbB3 binding protein and downstream effector of the ErbB signaling network was shown to be a potent tumor suppressor in breast and prostate adenocarcinomas. We hypothesized that the inhibitory properties of the ebp1 gene could also be beneficial if ectopically expressed in salivary adenoid carcinoma. Salivary adenoid carcinoma cell line (ACC-M) cells were stably transfected with the full-length ebp1 cDNA sequence or the empty expression vector pcDNA3.1. Stable gene transfer was verified by Western blot analysis and reverse transcription (RT)-PCR. A significant reduction in cell proliferation, anchorage-independent growth, and a change in the cell cycle profile was observed in ebp1 transfectants. Matrigel assays demonstrated that the adenoid cystic carcinoma cell invasiveness was significantly reduced. A strong decrease in the metastatic potential of human adenoid cystic carcinoma cells in an experimental metastatic model was also observed. Our results suggest that ectopic expression of Ebp1 mediates multiple antitumor activities against adenoid cystic carcinoma cells and that ebp1 gene therapy might be a viable method suppressing malignant salivary adenoid tumors.

Current views concerning the influences of murine hepatic endothelial adhesive and cytotoxic properties on interactions between metastatic tumor cells and the liver

Substantial recent experimental evidence has demonstrated the existence of reciprocal interactions between the microvascular bed of a specific organ and intravascular metastatic tumor cells through expression of adhesion molecules and nitric oxide release, resulting in a significant impact upon metastatic outcomes.

This review summarizes the current findings of adhesive and cytotoxic endothelial-tumor cell interactions in the liver, the inducibility, zonal distribution and sinusoidal structural influences on the hepatic endothelial regulatory functions, and the effects of these functions on the formation of liver cancer metastases. New insights into the traditional cancer metastatic cascade are also discussed.

Human T-cell lymphotropic virus type I-infected cells extravasate through the endothelial barrier by a local angiogenesis-like mechanism

Extravasation of tumor cells through the endothelial barrier is a critical step in cancer metastasis. Human T-cell lymphotropic virus type I (HTLV-I)-associated adult T-cell leukemia/lymphoma (ATL) is an aggressive disease characterized by visceral invasion. We show that ATL and HTLV-I-associated myelopathy patients exhibit high plasma levels of functional vascular endothelial growth factor and basic fibroblast growth factor. The viral oncoprotein Tax transactivates the promoter of the gap-junction protein connexin-43 and enhances gap-junction-mediated heterocellular communication with endothelial cells. The interaction of HTLV-I-transformed cells with endothelial cells induces the gelatinase activity of matrix metalloproteinase (MMP)-2 and MMP-9 in endothelial cells and down-regulates the tissue inhibitor of MMP. This leads to subendothelial basement membrane degradation followed by endothelial cell retraction, allowing neoplastic lymphocyte extravasation. We propose a model that offers a mechanistic explanation for extravasation of HTLV-I-infected cells: after specific adhesion to endothelia of target organs, tumor cells induce a local and transient angiogenesis-like mechanism through paracrine stimulation and direct cell-cell communication with endothelial cells. This culminates in a breach of the endothelial barrier function, allowing cancer cell invasion. This local and transient angiogenesis-like sequence that may facilitate visceral invasion in ATL represents a potential target for ATL therapy.

The rationale of perioperative intraperitoneal chemotherapy in the treatment of peritoneal surface malignancies

In summary, the use of perioperative intraperitoneal chemotherapy is a rational and scientifically sound treatment option for patients with peritoneal carcinomatosis. By delivering chemotherapeutic agents directly into the peritoneal cavity in the perioperative period, after cytoreductive procedures resulting in minimal residual tumor load, the cytotoxicity, efficacy, and safety of these agents can be maximized. The use of this treatment strategy in the intraoperative or perioperative period ensures that the efficacy of the chemotherapeutic agents is not reduced by limitations of abdominal compartmentalization and scarring. Treating patients under hyperthermic conditions may confer an additional benefit. Although the use of perioperative chemotherapy or hyperthermic intraperitoneal chemotherapy is not yet part of the standard of care for the treatment of advanced abdominal malignancies, both basic science and clinical investigations have confirmed the validity of these regimens. Further clinical studies in a cooperative group setting are necessary to prove the efficacy of perioperative intraperitoneal chemotherapy in both the treatment and prevention of peritoneal surface malignancy.