The biology of cancer invasion and metastasis

Molecular Mechanism of lncRNAs in Regulation of Breast Cancer Metastasis; a Comprehensive Review

Although the number of breast cancer deaths has decreased, and there have been developments in targeted therapies and combination treatments for the management of metastatic illness, metastatic breast cancer is still the second most common cause of cancer-related deaths in U.S. women. Numerous phases and a vast number of proteins and signaling molecules are involved in the invasion-metastasis cascade. The tumor cells penetrate and enter the blood or lymphatic vessels, and travel to distant organs via the lymphatic or blood vessels. Tumor cells enter cell cycle arrest, adhere to capillary beds in the target organ, and then disseminate throughout the organ's parenchyma, proliferating and enhancing angiogenesis. Each of these processes is regulated by changes in the expression of different genes, in which lncRNAs play a role in this regulation. Transcripts that are longer than 200 nucleotides and do not translate into proteins are called RNAs. LncRNA molecules, whose function depends on their unique molecular structure, play significant roles in controlling the expression of genes at various epigenetic levels, transcription, and so on. LncRNAs have essential functions in regulating the expression of genes linked to cell development in healthy and pathological processes, specialization, programmed cell death, cell division, invasion, DNA damage, and spread to other parts of the body. A number of cancer types have been shown to exhibit aberrant expression of lncRNAs. In this review, we describe the general characteristics, potential molecular mechanisms and targeted therapy of lncRNAs and discuss the emerging functions of lncRNAs in breast cancer.

YAP localization mediates mechanical adaptation of human cancer cells during extravasation in vivo

Biophysical profiling of primary tumors has revealed that individual tumor cells fall along a highly heterogeneous continuum of mechanical phenotypes. One idea is that a subset of tumor cells is "softer" to facilitate detachment and escape from the primary site, a step required to initiate metastasis. However, it has also been postulated that cells must be able to deform and generate sufficient force to exit into distant sites. Here, we aimed to dissect the mechanical changes that occur during extravasation and organ colonization. Using multiplexed methods of intravital microscopy and optical tweezer based active microrheology, we obtained longitudinal images and mechanical profiles of cells during organ colonization in vivo. We determined that cells were softer, more liquid like upon exit of the vasculature but stiffened and became more solid like once in the new organ microenvironment. We also determined that a YAP mediated mechanogenotype influenced the global dissemination in our in vivo and in vitro models and that reducing mechanical heterogeneity could reduce extravasation. Moreover, our high throughput analysis of mechanical phenotypes of patient samples revealed that this mechanics was in part regulated by the external hydrodynamic forces that the cancer cells experienced within capillary mimetics. Our findings indicate that disseminated cancer cells can keep mutating with a continuum landscape of mechano-phenotypes, governed by the YAP-mediated mechanosensing of hydrodynamic flow.

Genetic and nongenetic mechanisms for colorectal cancer evolution

The stepwise accumulation of key driver mutations is responsible for the development and malignant progression of colorectal cancer in primary sites. Genetic mouse model studies have revealed combinations of driver gene mutations that induce phenotypic changes in tumors toward malignancy. However, cancer evolution is regulated by not only genetic alterations but also nongenetic mechanisms. For example, certain populations of metastatic cancer cells show a loss of malignant characteristics even after the accumulation of driver mutations, and such cells are eliminated in a negative selection manner. Furthermore, a polyclonal metastasis model has recently been proposed, in which cell clusters consisting of genetically heterogeneous cells break off from the primary site, disseminate to distant organs, and develop into heterogenous metastatic tumors. Such nongenetic mechanisms for malignant progression have been elucidated using genetically engineered mouse models as well as organoid transplantation experiments. In this review article, we discuss the role of genetic alterations in the malignant progression of primary intestinal tumors and nongenetic mechanisms for negative selection and polyclonal metastasis, which we learned from model studies.

Pathology and Molecular Biology of Melanoma

Almost every death in young patients with an advanced skin tumor is caused by melanoma. Today, with the help of modern treatments, these patients survive longer or can even achieve a cure. Advanced stage melanoma is frequently related with poor prognosis and physicians still find this disease difficult to manage due to the absence of a lasting response to initial treatment regimens and the lack of randomized clinical trials in post immunotherapy/targeted molecular therapy settings. New therapeutic targets are emerging from preclinical data on the genetic profile of melanocytes and from the identification of molecular factors involved in the pathogenesis of malignant transformation. In the current paper, we present the diagnostic challenges, molecular biology and genetics of malignant melanoma, as well as the current therapeutic options for patients with this diagnosis.

Defining clonal hematopoiesis of indeterminate potential: evolutionary dynamics and detection under aging and inflammation

Clonal hematopoiesis (CH), in which hematopoietic stem and progenitor cell (HSPC) clones and their progeny expand in the circulating blood cell population, occurs following the acquisition of somatic driver mutations. Individuals diagnosed with clonal hematopoiesis of indeterminate potential (CHIP) carry somatic mutations in hematological malignancy-associated driver genes, historically at or above a variant allele frequency of 2%, but do not exhibit abnormal blood cell counts or any other symptoms of hematologic disease. However, CHIP is associated with moderately increased risk of hematological cancer and a greater likelihood of cardiovascular and pulmonary disease. Recent advances in the resolution of high-throughput sequencing experiments suggest CHIP is much more prevalent in the population than once thought, particularly among those aged 60 and over. Although CHIP does elevate the risk of eventual hematological malignancy, only one in 10 individuals with CHIP will receive such a diagnosis; the problem lies in the continued difficulty in accurately separating the 10% of CHIP patients who are most likely to be in a premalignant state from those who are not, given the heterogeneity of this condition and the etiology of the associated hematological cancers. Concerns over the risk of eventual malignancies must be balanced with growing recognition of CH as a common age-dependent occurrence, and efforts to better characterize and differentiate oncogenic clonal expansion from that which is much more benign. In this review, we discuss evolutionary dynamics of CH and CHIP, the relationship of CH to aging and inflammation, and the role of the epigenome in promoting potentially pathogenic or benign cellular trajectories. We outline molecular mechanisms that may contribute to heterogeneity in the etiology of CHIP and the incidence of malignant disease among individuals. Finally, we discuss epigenetic markers and modifications for CHIP detection and monitoring with the potential for translational applications and clinical utility in the near future.

Emerging role of mRNA methylation in regulating the hallmarks of cancer

The dynamic chemical modifications of DNA, RNA, and proteins can transform normal cells into malignant ones. While the DNA and protein modifications in cancer have been described extensively in the literature, there are fewer reports about the role of RNA modifications in cancer. There are over 100 forms of RNA modifications and one of these, mRNA methylation, plays a critical role in the malignant properties of the cells. mRNA methylation is a reversible modification responsible for regulating protein expression at the post-transcriptional level. Despite being discovered in the 1970s, a complete understanding of the different proteins involved and the mechanism behind mRNA methylation remains largely unknown. However, these mRNA methylations have been shown to foster cancer hallmarks via specific cellular targets inside the cell. In this review, we provide a brief overview of mRNA methylation and its emerging role in regulating the various hallmarks of cancer.

The roles of ERIANIN in tumor and innate immunity and its' perspectives in immunotherapy

Traditional Chinese medicine has been used in China for thousands of years. In 2022, the 14th Five-Year Plan for the Development of Traditional Chinese Medicine was released, aiming to enhance traditional Chinese medicine health services and improve policies and systems for high-quality traditional Chinese medicinal development by 2025. ERIANIN, the main component of the traditional Chinese medicine Dendrobium, plays an important role in anti-inflammatory, antiviral, antitumor, antiangiogenic, and other pharmacological effects. ERIANIN has broad-spectrum antitumor effects, and its tumor-suppressive effects have been confirmed in the study of various diseases, such as precancerous lesions of the stomach, gastric cancer, liver cancer, lung cancer, prostate cancer, bladder cancer, breast cancer, cervical cancer, osteosarcoma, colorectal cancer, leukaemia, nasopharyngeal cancer and melanoma through the multiple signaling pathways. Thus, the aim of this review was to systematically summarise the research on ERIANIN with the aim of serving as a reference for future research on this compound and briefly discuss some future perspectives development of ERIANIN in combined immunotherapy.

The metastatic niche formation: focus on extracellular vesicle-mediated dialogue between lung cancer cells and the microenvironment

Lung cancer is the deadliest cancer in the world, with the majority of patients presenting with advanced or metastatic disease at first diagnosis. The lungs are also one of the most common sites of metastasis from lung cancer and other tumors. Understanding the mechanisms that regulate metastasis formation from primary lung cancer and in the lungs is therefore fundamental unmet clinical need. One of the first steps during the establishment of lung cancer metastases includes the formation of the pre-metastatic niche (PMN) at distant organs, which may occur even during the early phases of cancer development. The PMN is established through intricate cross-talk between primary tumor-secreted factors and stromal components at distant sites. Mechanisms controlling primary tumor escape and seeding of distant organs rely on specific properties of tumor cells but are also tightly regulated by interactions with stromal cells at the metastatic niche that finally dictate the success of metastasis establishment. Here, we summarize the mechanisms underlying pre-metastatic niche formation starting from how lung primary tumor cells modulate distant sites through the release of several factors, focusing on Extracellular Vesicles (EVs). In this context, we highlight the role of lung cancer-derived EVs in the modulation of tumor immune escape. Then, we illustrate the complexity of Circulating Tumor Cells (CTCs) that represent the seeds of metastasis and how interactions with stromal and immune cells can help their metastatic dissemination. Finally, we evaluate the contribution of EVs in dictating metastasis development at the PMN through stimulation of proliferation and control of disseminated tumor cell dormancy. Overall, we present an overview of different steps in the lung cancer metastatic cascade, focusing on the EV-mediated interactions between tumor cells and stromal/immune cells.

CDCA7 promotes TGF-β-induced epithelial-mesenchymal transition via transcriptionally regulating Smad4/Smad7 in ESCC

Cell division cycle associated 7 (CDCA7) is a copy number amplification gene that contributes to the metastasis and invasion of tumors, including esophageal squamous cell carcinoma (ESCC). This present study aimed at clarifying whether high expression of CDCA7 promotes the metastasis and invasion of ESCC cell lines and exploring the underlying mechanisms implicated in epithelial-mesenchymal transition (EMT) of ESCC. The role of CDCA7 in the regulation of ESCC metastasis and invasion was evaluated using ESCC cell lines. Expression of EMT-related markers including E-cadherin, N-cadherin, Vimentin, Snail, and Slug, transforming growth factor β (TGF-β) signaling pathway including Smad2/3, p-Smad2/3, Smad4, and Smad7 were detected in CDCA7 knockdown and overexpressed cell lines. Dual-luciferase reporter assay and rescue assay were used to explore the underlying mechanisms that CDCA7 contributed to the metastasis and invasion of ESCC. High CDCA7 expression significantly promoted the metastasis and invasion of ESCC cell lines both in vivo and in vitro. Additionally, the expression of CDCA7 positively correlated with the expression of N-cadherin, Vimentin, Snail, Slug, TGF-β signaling pathway and negatively correlated with the expression of E-cadherin. Furthermore, CDCA7 transcriptionally regulated the expression of Smad4 and Smad7. Knockdown of CDCA7 inhibited the TGF-β signaling pathway and therefore inhibited EMT. Our data indicated that CDCA7 was heavily involved in EMT by regulating the expression of Smad4 and Smad7 in TGF-β signaling pathway. CDCA7 might be a new therapeutic target in the suppression of metastasis and invasion of ESCC.

Psychosocial stress and cancer risk: a narrative review

BACKGROUND

It is unclear which psychological factors (stressors, emotional correlates, and psychophysiological markers) induce cancer risk. This currently limits the potential for prevention strategies.

PURPOSE

The aim of this review is to bring forth evidence of stress as a determinant of cancer risk from a public health perspective, written for a broad public of practitioners and scientists.

METHODS

Based on a semisystematic literature search, the impact of different aspects/types of stress and the potential physiological and behavioral pathways are summarized, while highlighting further research, public health and clinical implications.

RESULTS

Between 2007 and 2020, 65 case-control or cohort studies have been identified. Apart from overall cancer ( N = 24), 12 cancer types have been associated with psychological stress with most for breast ( N = 21), colorectal ( N = 11) and lung/prostate/pancreas cancer ( N = 8 each). Although the evidence regarding the mechanisms is still scarce, cancer development in relation to stress might be due to interacting and combined effects of different stress(or) types, but such interaction has not really been tested yet. The path from stress towards cancer incidence consists of a biological pathway with endocrinology and immunology as well as stress-induced behavioral pathways, including smoking, alcoholism, sleep disruption, an unhealthy diet, and low physical activity together with the related phenomenon of obesity.

CONCLUSION

Not only the stress but also the stress-induced lifestyle should be targeted for cancer prevention and treatment. Future research should include a more diverse spectrum of cancer types (not only hormonal related like breast cancer) and of stress measures while also considering behavioral covariates.

Overview of radiomics in prostate imaging and future directions

Recent advancements in imaging technology and analysis methods have led to an analytic framework known as radiomics. This framework extracts comprehensive high-dimensional features from imaging data and performs data mining to build analytical models for improved decision-support. Its features include many categories spanning texture and shape; thus, it can provide abundant information for precision medicine. Many studies of prostate radiomics have shown promising results in the assessment of pathological features, prediction of treatment response, and stratification of risk groups. Herein, we aimed to provide a general overview of radiomics procedures, discuss technical issues, explain various clinical applications, and suggest future research directions, especially for prostate imaging.

Metastatic Breast Cancer, Organotropism and Therapeutics: A Review

The final stage of breast cancer involves spreading breast cancer cells to the vital organs like the brain, liver lungs and bones in the process called metastasis. Once the target organ is overtaken by the metastatic breast cancer cells, its usual function is compromised causing organ dysfunction and death. Despite the significant research on breast cancer metastasis, it's still the main culprit of breast cancer-related deaths. Exploring the complex molecular pathways associated with the initiation and progression of breast cancer metastasis could lead to the discovery of more effective ways of treating the devastating phenomenon. The present review article highlights the recent advances to understand the complexity associated with breast cancer metastases, organotropism and therapeutic advances.

Intra-heterogeneity in transcription and chemoresistant property of leukemia-initiating cells in murine Setd2-/- acute myeloid leukemia

BACKGROUND

Heterogeneity of leukemia-initiating cells (LICs) is a major obstacle in acute myeloid leukemia (AML) therapy. Accumulated evidence indicates that the coexistence of multiple types of LICs with different pathogenicity in the same individual is a common feature in AML. However, the functional heterogeneity including the drug response of coexistent LICs remains unclear. Therefore, this study aimed to clarify the intra-heterogeneity in LICs that can help predict leukemia behavior and develop more effective treatments.

METHODS

Spleen cells from the primary Setd2^-/- -AML mouse were transplanted into C57BL/6 recipient mice to generate a transplantable model. Flow cytometry was used to analyze the immunophenotype of the leukemic mice. Whole-genome sequencing was conducted to detect secondary hits responsible for leukemia transformation. A serial transplantation assay was used to determine the self-renewal potential of Setd2^-/- -AML cells. A limiting-dilution assay was performed to identify the LIC frequency in different subsets of leukemia cells. Bulk and single-cell RNA sequencing were performed to analyze the transcriptional heterogeneity of LICs. Small molecular inhibitor screening and in vivo drug treatment were employed to clarify the difference in drug response between the different subsets of LICs.

RESULTS

In this study, we observed an aged Setd2^-/- mouse developing AML with co-mutation of Nras^G12S and Braf^K520E . Further investigation identified two types of LICs residing in the c-Kit⁺ B220⁺ Mac-1^- and c-Kit⁺ B220⁺ Mac-1⁺ subsets, respectively. In vivo transplantation assay disclosed the heterogeneity in differentiation between the coexistent LICs. Besides, an intrinsic doxorubicin-resistant transcriptional signature was uncovered in c-Kit⁺ B220⁺ Mac-1⁺ cells. Indeed, doxorubicin plus cytarabine (DA), the standard chemotherapeutic regimen used in AML treatment, could specifically kill c-Kit⁺ B220⁺ Mac-1^- cells, but it hardly affected c-Kit⁺ B220⁺ Mac-1⁺ cells. Transcriptome analysis unveiled a higher activation of RAS downstream signaling pathways in c-Kit⁺ B220⁺ Mac-1⁺ cells than in c-Kit⁺ B220⁺ Mac-1^- cells. Combined treatment with DA and RAS pathway inhibitors killed both c-Kit⁺ B220⁺ Mac-1^- and c-Kit⁺ B220⁺ Mac-1⁺ cells and attenuated disease progression.

CONCLUSIONS

This study identified two cell subsets enriched for LICs in murine Setd2^-/- -AML and disclosed the transcriptional and functional heterogeneity of LICs, revealing that the coexistence of different types of LICs in this model brings about diverse drug response.

The evolution of leukaemia from pre-leukaemic and leukaemic stem cells

Haematopoietic stem and progenitor cells (HSPCs) are defined as unspecialized cells that give rise to more differentiated cells. In a similar way, leukaemic stem and progenitor cells (LSPCs) are defined as unspecialized leukaemic cells, which can give rise to more differentiated cells. Leukaemic cells carry leukaemic mutations/variants and have clear differentiation abnormalities. Pre-leukaemic HSPCs (PreL-HSPCs) carry pre-leukaemic mutations/variants (pLMs) and are capable of producing mature functional cells, which will carry the same variants. Under the roof of LSPCs, one can find a broad range of cell types genetic and disease phenotypes. Present-day knowledge suggests that this phenotypic heterogeneity is the result of interactions between the cell of origin, the genetic background and the microenvironment background. The combination of these attributes will define the LSPC phenotype, frequency, differentiation capacity and evolutionary trajectory. Importantly, as LSPCs are leukaemia-initiating cells that sustain clinical remission and are the source of relapse, an improved understanding of LSPCs phenotype would offer better clinical opportunities for the treatment and hopefully prevention of human leukaemia. The current review will focus on LSPCs attributes in the context of human haematologic malignancies.

Tumor-associated neutrophils (TANs) in human carcinoma-draining lymph nodes: a novel TAN compartment

Objectives

The role of tumor‐associated neutrophils (TANs) in the nodal spread of cancer cells remains unexplored. The present study evaluates the occurrence and clinical significance of human nodal TANs.

Methods

The relevance, derivation, phenotype and interactions of nodal TANs were explored via a large immunohistochemical analysis of carcinoma‐draining lymph nodes, and their clinical significance was evaluated on a retrospective cohort of oral squamous cell carcinomas (OSCC). The tumor‐promoting function of nodal TAN was probed in the OSCC TCGA dataset combining TAN and epithelial‐to‐mesenchymal transition (EMT) signatures.

Results

The pan‐carcinoma screening identified a consistent infiltration (59%) of CD66b⁺  TANs in tumor‐draining lymph nodes (TDLNs). Microscopic findings, including the occurrence of intra‐lymphatic conjugates of TANs and cancer cells, indicate that TANs migrate through lymphatic vessels. In vitro experiments revealed that OSCC cell lines sustain neutrophil viability and activation via release of GM‐CSF. Moreover, by retrospective analysis, a high CD66b⁺ TAN density in M‐TDLNs of OSCC (n = 182 patients) predicted a worse prognosis. The analysis of the OSCC‐TCGA dataset unveiled that the expression of a set of neutrophil‐specific genes in the primary tumor (PT) is highly associated with an EMT signature, which predicts nodal spread. Accordingly, in the PT of OSCC cases, CD66b⁺TANs co‐localised with PDPN⁺S100A9⁻ EMT‐switched tumor cells in areas of lymphangiogenesis. The pro‐EMT signature is lacking in peripheral blood neutrophils from OSCC patients, suggesting tissue skewing of TANs.

Conclusion

Our findings are consistent with a novel pro‐tumoral TAN compartment that may promote nodal spread via EMT, through the lymphatics.

Plasma protein-based signature predicts distant metastasis and induction chemotherapy benefit in Nasopharyngeal Carcinoma

Rationale: Currently, for locoregionally advanced nasopharyngeal carcinoma (LA-NPC), there is no effective blood-based method to predict distant metastasis. We aimed to detect plasma protein profiles to identify biomarkers that could distinguish patients with NPC who are at high risk of posttreatment distant metastasis.

Methods: A high-throughput antibody array was initially applied to detect 1000 proteins in pretreatment plasma from 16 matched LA-NPC patients with or without distant metastasis after radical treatment. Differentially expressed proteins were further examined using a low-throughput array to construct a plasma protein-based signature for distant metastasis (PSDM) in a cohort of 226 patients.

Results: Fifty circulating proteins were differentially expressed between metastatic and non-metastatic patients and 18 were proven to be strongly correlated with distant metastasis-free survival (DMFS) in NPC. A PSDM signature consisting of five proteins (SLAMF5, ESM-1, MMP-8, INSR, and Serpin A5) was established to assign patients with NPC into a high-risk group and a low-risk group. Patients in the high-risk group had shorter DMFS (P < 0.001), disease-free survival (DFS) (P < 0.001) and overall survival (OS) (P < 0.001). Moreover, the PSDM performed better than N stage and Epstein-Barr virus (EBV) DNA load at effectively identifying patients with NPC at high risk of metastasis. For patients in the high-risk group, induction chemotherapy significantly improved DMFS, DFS, and OS.

Conclusions: The PSDM could be a useful liquid biopsy tool to effectively predict distant metastasis and the benefit of induction chemotherapy in patients with LA-NPC.

p53: An Attractive Therapeutic Target for Cancer

Cancer is a leading cause of death worldwide. It initiates when cell cycle regulatory genes lose their function either by environmental and/or by internal factors. Tumor suppressor protein p53, known as "Guardian of genome", plays a central role in maintaining genomic stability of the cell. Mutation of TP53 is documented in more than 50% of human cancers, usually by overexpression of negative regulator protein MDM2. Hence, reactivation of p53 by blocking the protein-protein interaction between the murine double minute 2 (MDM2) and the tumor suppressor protein p53 has become the most promising therapeutic strategy in oncology. Several classes of small molecules have been identified as potent, selective and efficient p53-MDM2 inhibitors. Herein, we review the druggability of p53-MDM2 inhibitors and their optimization approaches as well as clinical candidates categorized by scaffold type.

New insights into the mechanisms of epithelial-mesenchymal transition and implications for cancer

Epithelial-mesenchymal transition (EMT) is a cellular programme that is known to be crucial for embryogenesis, wound healing and malignant progression. During EMT, cell-cell and cell-extracellular matrix interactions are remodelled, which leads to the detachment of epithelial cells from each other and the underlying basement membrane, and a new transcriptional programme is activated to promote the mesenchymal fate. In the context of neoplasias, EMT confers on cancer cells increased tumour-initiating and metastatic potential and a greater resistance to elimination by several therapeutic regimens. In this Review, we discuss recent findings on the mechanisms and roles of EMT in normal and neoplastic tissues, and the cell-intrinsic signals that sustain expression of this programme. We also highlight how EMT gives rise to a variety of intermediate cell states between the epithelial and the mesenchymal state, which could function as cancer stem cells. In addition, we describe the contributions of the tumour microenvironment in inducing EMT and the effects of EMT on the immunobiology of carcinomas.

Fluorescent Polysaccharide Nanogels for the Detection of Tumor Heterogeneity in Drug-Surviving Cancer Cells

Tumor metastasis, recurrence, and drug resistance have been associated with tumor heterogeneity, and thus the identification of tumor heterogeneity has great significance in medicine. The approach provides a way to identify and isolate various cell subtypes from drug-surviving ovarian cancer cells, by synthesizing a series of polysaccharide nanogels and using them in flow cytometry analysis. The results show that the drug-surviving OVCAR-3 cells that are subjected to paclitaxel intervention comprise various cell subtypes, including drug-resistant and non-drug-resistant cell subtypes. Besides, there are significant differences between the drug-resistant cell subtype and non-drug-resistant cell subtype in terms of their migration and invasion behavior. In addition, the phenotype switch genes are detected by mRNA sequencing, and it is found that different subtypes show significant genetic differences with regard to their drug resistance, metastasis, and proliferation. In particular, modifying polysaccharide nanogels with lipids can promote the uptake of nanogels by drug-resistant cells, and thus the lipid modification can enhance the effectiveness of a chemotherapy drug carrier against drug-resistant cells. These studies reveal the heterogeneity of drug-surviving tumor cells, as well as the significant differences in drug-resistance, migration, and invasion capabilities of different subtypes, and demonstrate a way to overcome drug resistance.

Treating tumors with minimally invasive therapy: A review

With high level of morbidity and mortality, tumor is one of the deadliest diseases worldwide. Aiming to tackle tumor, researchers have developed a lot of strategies. Among these strategies, the minimally invasive therapy (MIT) is very promising, for its capability of targeting tumor cells and resulting in a small incision or no incisions. In this review, we will first illustrate some mechanisms and characteristics of tumor metastasis from the primary tumor to the secondary tumor foci. Then, we will briefly introduce the history, characteristics, and advantages of some of the MITs. Finally, emphasis will be, respectively, focused on an overview of the state-of-the-art of the HIFU-, PDT-, PTT-and SDT-based anti-tumor strategies on each stage of tumor metastasis.

Nanomedicinal strategies as efficient therapeutic interventions for delivery of cancer vaccines

The applications of gene therapy-based treatment of cancers were started almost two decades back as a boon over the chemotherapeutic treatment strategies. Gene therapy helps in correcting the genetic sequences for treatment of cancers, thus also acts like a vaccine to induce the cellular and humoral immunity. However, the cancer vaccines typically suffer from a series of biopharmaceutical challenges due to poor solubility, low systemic availability and lack of targeting ability. Owing to these challenges, the physicians and pharmaceutical scientists have explored the applications of nanocarriers as quite promising systems for effective treatment against the tumors. A series of nanotherapeutic systems are available to date for diverse drug therapy applications. Systematic understanding on the preparation, evaluation and application of nanomedicines as a carrier system for delivering the cancer vaccines is highly important. The present review article provides an in-depth understanding on the challenges associated with cancer vaccine delivery and current opportunities with diverse nanomedicinal carriers being available for treatment of cancers.

Observations on Solitary Versus Multiple Isolated Pancreatic Metastases of Renal Cell Carcinoma: Another Indication of a Seed and Soil Mechanism?

Isolated pancreas metastases are a rare type of metastasis of renal cell carcinoma, characterized by the presence of pancreatic metastases, while all other organs remain unaffected. In a previous study, we determined arguments from the literature which (a) indicate a systemic-haematogenic metastasis route (uniform distribution of the metastases across the pancreas and independence of the metastatic localization in the pancreas of the side of the renal carcinoma); and (b) postulate a high impact of a seed and soil mechanism (SSM) on isolated pancreatic metastasis of renal cell carcinoma (isPM) as an explanation for exclusive pancreatic metastases, despite a systemic haematogenous tumor cell embolization. The objective of the study presented was to search for further arguments in favor of an SSM with isPM. For that purpose, the factor's histology, grading, and singular/multiple pancreas metastases were analyzed on the basis of 814 observations published up to 2018. While histology and grading allowed for no conclusions regarding the importance of an SSM, the comparison of singular/multiple pancreas metastases produced arguments in favor of an SSM: 1. The multiple pancreas metastases observed in 38.1% prove that multiple tumor cell embolisms occur with isPM, the exclusive "maturation" of which in the pancreas requires an SSM; 2. The survival rates (SVR), which are consistent with singular and multiple pancreas metastases (despite the higher total tumor load with the latter), prove that the metastasized tumor cells are not able to survive in all other organs because of an SSM, which results in identical SVR when the pancreatic foci are treated adequately.

A new proposal of utilizing intraoperative electron radiation therapy on the surface of liver to prevent postoperative liver metastasis of pancreatic cancer

Pancreatic cancer is a lethal cancer with high rate of liver metastasis worldwide, whereas its treatment choices are limited to a large extent. The limitation of current therapeutic strategies calls for an effective approach which can lower the postoperative liver metastasis rate in order to improve the overall prognosis and survival rate. Comprehensively considering the basic knowledge and clinical practice of tumor treatment worldwide, we proposed three points of hypotheses. Basically, the existing evidences indicated that tumor cells shedding from pancreatic cancer localized in the marginal liver preferentially through the Portal vein. Then, the percentage depth dose distribution of electron radiation is consistent with the marginal distribution of liver metastasis from pancreatic cancer. Based on the characteristics of liver metastasis of pancreatic cancer and the percentage depth dose of electron radiation, we provide a new propose of preventing postoperative liver metastasis in a way of prophylactic intraoperative electron radiation therapy on the surface of liver. Intraoperative electron radiation is relatively easy to control radiation dose and treatment area under direct vision, effectively inhibiting the metastasis and growth of cancer cells and preventing further deterioration of pancreatic cancer patients' condition. Therefore, this hypothesis has an important clinical significance for postoperative rehabilitation and improvement of patients' survival.

Isolated pancreatic metastases from renal cell carcinoma: an outcome of a special metastatic pathway or of specific tumor cell selection?

Isolated pancreatic metastases (isPM) are a rare metastasizing pattern in the natural history of renal cell cancer. Their clinical hallmark is that they are confined to a single organ, the pancreas, while all other organs are unaffected for a long time. Almost all workers in the field suggested that mechanical tumor cell propagation to the pancreas may be the mechanism underlying this metastasizing pattern. In 2006 our group, by contrast, proposed an alternative mechanism, i.e. a special affinity of the tumor cells for the pancreas. In the present study an attempt was made to shed more light on the settlement of isPM by reviewing recent literature data. 666 observations of isPM reported in the literature were reviewed. The analyses showed that local lymphatic spread does not play a major role because the lymphatic system is, in general, rarely involved in isPM. This also applies to a local venous spread, because the site of pancreatic metastases is independent of the side affected by the primary renal cancer. But the results are compatible with a systemic metastatic pathway. That metastases in other organs, which would be expected given a systemic spread, are absent can plausibly be explained by a seed and soil mechanism: only the pancreas offers the tumor cell emboli an environment which is conducive to the growth of clinically manifest metastases, while settlement of metastatic tumor cells is prevented in all other organs.

Metastatic efficiency of tumour cells can be impaired by intraoperative cell salvage process: truth or conjecture?

The use of salvaged blood in oncological surgery has been a matter of controversy over the years. This is due to the concern of systemic dissemination of reinfused tumour cells. Recent literature, across disciplines, has shed considerable light on its safety in terms of tumour recurrence, progression and overall survival rates. This clinical safety demonstrates the apparent metastatic inefficiency of reinfused tumour cells. The proof of this concept comes from various studies that have shown that salvaged blood has no tumour cells, or has a significantly lower count as compared to the patient's original circulatory tumour load. Recently, we took a step further and found that the tumour cells in the salvaged blood lose the capacity to replicate. In this review, we revisited the safety of salvaged blood from the point of view of metastatic potential. We have presented basic and applied science evidence regarding the innocuous nature of tumour cells that have been subjected to the cell salvage process. The understanding of the metastatic efficiency or the lack of it in tumour cells subjected to salvage process is key to allay the concerns conventionally associated with the use of salvaged blood in tumour surgery. Based on the available literature, we surmise that the prevalent apprehensions on the usage of salvaged blood are ill-founded and further substantiate why tumour cells in the salvaged blood could be regarded as cells with non-metastatic potential.

The evolving concept of liver cancer stem cells

Liver cancer is an often fatal malignant tumor with a high recurrence rate and chemoresistance. The major malignant phenotypes of cancer, including recurrence, metastasis, and chemoresistance, are related to the presence of cancer stem cells (CSCs). In the past few decades, CSCs have been identified and characterized in many tumors including liver cancer. Accumulated evidence has revealed many aspects of the biological behavior of liver CSCs and the mechanism of their regulation. Based on these findings, a number of studies have investigated eradication of liver CSCs. This review focuses on the recent advances in our understanding of the biology of liver CSCs and the development of strategies for their treatment.

Extract of Monascus purpureus CWT715 Fermented from Sorghum Liquor Biowaste Inhibits Migration and Invasion of SK-Hep-1 Human Hepatocarcinoma Cells

Liver cancer is the most endemic cancer in a large region of the world. This study investigated the anti-metastatic effects of an extract of Monascus purpureus CWT715 (MP) fermented from sorghum liquor biowaste and its mechanisms of action in highly metastatic human hepatocarcinoma SK-Hep-1 cells. Kinmen sorghum liquor waste was used as the primary nutrient source to produce metabolites (including pigments) of MP. In the presence of 10 µg/mL MP-fermented broth (MFB), the anti-invasive activity increased with increasing fermentation time reaching a maximum at six days of fermentation. Interestingly, MFB also produced maximal pigment content at six days. Treatment for 24 h with MFB (10–100 µg/mL) obtained from fermentation for six days significantly inhibited cell migration and invasion, and these effects were concentration-dependent. MFB also significantly enhanced nm23-H1 protein expression in a concentration-dependent manner, which was highly correlated with migration and invasion. These results suggest that MFB has significant anti-migration and anti-invasion activities and that these effects are associated with the induction of nm23-H1 protein expression.

Cultured circulating tumor cells and their derived xenografts for personalized oncology

Recent cancer research has demonstrated the existence of circulating tumor cells (CTCs) in cancer patient's blood. Once identified, CTC biomarkers will be invaluable tools for clinical diagnosis, prognosis and treatment. In this review, we propose ex vivo culture as a rational strategy for large scale amplification of the limited numbers of CTCs from a patient sample, to derive enough CTCs for accurate and reproducible characterization of the biophysical, biochemical, gene expressional and behavioral properties of the harvested cells. Because of tumor cell heterogeneity, it is important to amplify all the CTCs in a blood sample for a comprehensive understanding of their role in cancer metastasis. By analyzing critical steps and technical issues in ex vivo CTC culture, we developed a cost-effective and reproducible protocol directly culturing whole peripheral blood mononuclear cells, relying on an assumed survival advantage in CTCs and CTC-like cells over the normal cells to amplify this specified cluster of cancer cells.

Curculigoside augments cell-mediated immune responses in metastatic tumor-bearing animals

A positive modulation of immune system is necessary for preparing the body to fight against malignant tumor cells. In the present study, the stimulatory effect of Curculigoside on cell-mediated immune response against the metastasis of B16F10 melanoma cells was analyzed in C57BL/6 mice. Curculigoside is a phenolic glucoside present in the plant Curculigo orchioides Gaertn. (Family - Amaryllidaceae). Administration of Curculigoside enhanced the natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity and complement-mediated cytotoxicity in metastatic tumor-bearing animals, when compared to the untreated control animals. The compound was also found to be effective in reducing the levels of proinflammatory cytokines such as TNF-α, IL-1β, IL-6 and GM-CSF during metastasis. Besides these, levels of TH1 cytokines, such as IL-2 and IFN-γ, were significantly enhanced (p < 0.001) by Curculigoside administration and thereby reduces the metastatic lung colony formation along with an increased lifespan of the experimental animals. These studies provide an evidence for the stimulation of cell-mediated immune responses by Curculigoside against B16F10-induced metastatic tumor progression in experimental animals.

Minimal residual disease in breast cancer: an overview of circulating and disseminated tumour cells

Within the field of cancer research, focus on the study of minimal residual disease (MRD) in the context of carcinoma has grown exponentially over the past several years. MRD encompasses circulating tumour cells (CTCs)—cancer cells on the move via the circulatory or lymphatic system, disseminated tumour cells (DTCs)—cancer cells which have escaped into a distant site (most studies have focused on bone marrow), and resistant cancer cells surviving therapy—be they local or distant, all of which may ultimately give rise to local relapse or overt metastasis. Initial studies simply recorded the presence and number of CTCs and DTCs; however recent advances are allowing assessment of the relationship between their persistence, patient prognosis and the biological properties of MRD, leading to a better understanding of the metastatic process. Technological developments for the isolation and analysis of circulating and disseminated tumour cells continue to emerge, creating new opportunities to monitor disease progression and perhaps alter disease outcome. This review outlines our knowledge to date on both measurement and categorisation of MRD in the form of CTCs and DTCs with respect to how this relates to cancer outcomes, and the hurdles and future of research into both CTCs and DTCs.

Xenotransplantation elicits salient tumorigenicity of adult T-cell leukemia-derived cells via aberrant AKT activation

The transplantation of human cancer cells into immunodeficient NOD/SCID/IL‐2Rγc^null (NOG) mice often causes highly malignant cell populations like cancer stem cells to emerge. Here, by serial transplantation in NOG mice, we established two highly tumorigenic adult T‐cell leukemia‐derived cell lines, ST1‐N6 and TL‐Om1‐N8. When transplanted s.c., these cells formed tumors significantly earlier and from fewer initial cells than their parental lines ST1 and TL‐Om1. We found that protein kinase B (AKT) signaling was upregulated in ST1‐N6 and TL‐Om1‐N8 cells, and that this upregulation was due to the decreased expression of a negative regulator, INPP5D. Furthermore, the introduction of a constitutively active AKT mutant expression vector into ST1 cells augmented the tumorigenicity of the cells, whereas treatment with the AKT inhibitor MK‐2206 attenuated the progression of tumors induced by ST1‐N6 cells. Collectively, our results reveal that the AKT signaling pathway plays a critical role in the malignancy of adult T‐cell leukemia‐derived cells.

Phase 1 trial design: is 3 + 3 the best?

BACKGROUND

Concerns have been recognized about the operating characteristics of the standard 3 + 3 dose-escalation design. Various innovative phase 1 trial designs have been proposed to address the issues and new challenges posed by molecularly targeted agents. However, in spite of these proposals, the conventional design is still the most widely utilized.

METHODS

A review of the literature of phase 1 trials and relevant statistical studies was performed.

RESULTS

Beyond statistical simulations, sparse clinical data exist to support or refute many of the shortcomings ascribed to the 3 + 3 rule method. Data from phase 1 trials demonstrate that traditional designs identified the correct dose and relevant toxicities with an acceptable level of precision in some instances; however, no single escalation method was proven superior in all circumstances.

CONCLUSIONS

Design selection should be guided by the principle of slow escalation in the face of toxicity and rapid dose increases in the setting of minimal or no adverse events. When the toxicity of a drug is uncertain or a narrow therapeutic window is suggested from preclinical testing, then a conservative 3 + 3 method is generally appropriate. However, if the therapeutic window is wide and the expected toxicity is low, then rapid escalation with a novel rule- or model-based design should be employed.

Lanthanide-doped luminescent nano-bioprobes for the detection of tumor markers

Sensitive and specific biodetection of tumor markers is essential for early-stage cancer diagnosis and therapy, and will ultimately increase the patient survival rate. As a new generation of luminescent bioprobes, lanthanide (Ln(3+))-doped inorganic luminescent nanoparticles have attracted considerable interest for a variety of biomedical applications due to their superior physicochemical properties. In this feature article, we provide a brief overview of the most recent advances in the development of Ln(3+)-doped luminescent nano-bioprobes and their promising applications for in vitro detection of tumor markers with an emphasis on the establishment of state-of-the-art assay techniques, such as heterogeneous time-resolved (TR) luminescent bioassay, dissolution-enhanced luminescent bioassay, upconversion (UC) luminescent bioassay, homogeneous TR Förster resonance energy transfer (TR-FRET) and UC-FRET bioassays. Some future prospects and efforts towards this emerging field are also envisioned.

CARP is a potential tumor suppressor in gastric carcinoma and a single-nucleotide polymorphism in CARP gene might increase the risk of gastric carcinoma

Background

The caspase-associated recruitment domain-containing protein (CARP) is expressed in almost all tissues. Recently, the tumor-suppressive function of CARP was discovered and attracted increasing attention. This study aimed to investigate the role of CARP in the carcinogenesis of human gastric carcinoma.

Methodology/Principal Findings

Compared with normal gastric tissue, the downregulation of CARP expression was observed in gastric carcinoma tissue by cDNA array and tissue microarray assay. In vitro, the gastric carcinoma cell line (BGC-823) was stably transfected with pcDNA3.1B-CARP or plus CARP siRNA, and we used MTT, flow cytometry, cell migration on type I collagen, cell-matrix adhesion assay and western blot analysis to investigate the potential anti-tumor effects of CARP. The data showed that overexpressing CARP suppressed the malignancy of gastric carcinoma BGC-823 cell line, including significant increases in apoptosis, as well as obvious decreases in cell proliferation, migration, adhesion ability, and tumor growth. The tumor-suppressive effects of CARP were almost restored by siRNA-directed CARP silence. In addition, overexpression of CARP induced G1 arrest, decreased the expressions of cyclin E and CDK2, and increased the expressions of p27, p53 and p21. In vivo, the tumor-suppressive effect of CARP was also verified. A single-nucleotide polymorphism (SNP) genotype of CARP (rs2297882) was located in the Kozak sequence of the CARP gene. The reporter gene assay showed that rs2297882 TT caused an obvious downregulation of activity of CARP gene promoter in BGC-823 cells. Furthermore, the association between rs2297882 and human gastric carcinoma susceptibility was analyzed in 352 cases and 889 controls. It displayed that the TT genotype of rs2297882 in the CARP gene was associated with an increased risk of gastric carcinoma.

Conclusions/Significance

CARP is a potential tumor suppressor of gastric carcinoma and the rs2297882 C>T phenotype of CARP may serve as a predictor of gastric carcinoma.

History of myeloid-derived suppressor cells

Tumour-induced granulocytic hyperplasia is associated with tumour vasculogenesis and escape from immunity via T cell suppression. Initially, these myeloid cells were identified as granulocytes or monocytes; however, recent studies have revealed that this hyperplasia is associated with populations of multipotent progenitor cells that have been identified as myeloid-derived suppressor cells (MDSCs). The study of MDSCs has provided a wealth of information regarding tumour pathobiology, has extended our understanding of neoplastic progression and has modified our approaches to immune adjuvant therapy. In this Timeline article, we discuss the history of MDSCs, their influence on tumour progression and metastasis, and the crosstalk between tumour cells, MDSCs and the host macroenvironment.

Emerging insights into head and neck cancer metastasis

The purpose of this review was to provide biological concepts of head and neck cancer metastasis. To attain this goal, we analyzed peer-reviewed articles related to head and neck cancer metastasis obtained though PubMed and archived articles. Articles related to the biologic principles of head and neck cancer metastasis were reviewed and summarized. As locoregional control has improved for patients with head and neck cancer, rates of distant metastasis have not decreased. As patients live longer, many will die of complications related to the development of disease at sites below the clavicles. Emerging evidence now suggests a more complicated framework of metastatic behavior for head and neck cancer. Here, we review the role of regional lymph nodes in containing advanced head and neck cancer, evidence for active as opposed to passive tumor cell metastasis, and clinical implications these concepts have on both treatment of head and neck cancer and future research.

Inhibitory effect of serum from rats administered with coffee on the proliferation and invasion of rat ascites hepatoma cells

The action of coffee on the proliferation and invasion of a rat ascites hepatoma cell line of AH109A was investigated using in vitro and ex vivo assay systems. When rats were given oral intubation of instant coffee powder solution, the sera of those rats had the potent inhibitory activity on both the proliferation and invasion of AH109A. The activity of rat serum was both time- and dose-dependent. The instant coffee powder also inhibited the proliferation and invasion of AH109A in vitro. These results indicate that coffee has anti-proliferative and anti-invasive activity both in vitro and ex vivo. They also suggest that some anti-proliferative and anti-invasive material(s), which may be the ingredient(s) of coffee or their metabolites, appear in rat serum when rats are given oral intubation of coffee, although a possibility that host defense systems may be activated by the oral intubation of coffee cannot be ruled out.

Assay systems for screening food components that have anti-proliferative and anti-invasive activity to rat ascites hepatoma cells: In vitro and ex vivo effects of green tea extract

We have developed in vitro and ex vivo assay systems for screening food components and natural substances that suppress the proliferation and/or invasion of a rat ascites hepatoma cell line of AH109A and have used them to study the effect of green tea extract. AH109A cells were found to penetrate underneath the monolayer of primary cultured mesothelial cells isolated from Donryu rat mesentery in the presence of 10% newborn bovine serum. Green tea extract inhibited this AH109A penetration in a dose dependent manner and also inhibited AH109A proliferation in vitro dose-dependently. Green tea tannin, the major polyphenolic substances in green tea extract, also inhibited the proliferation and invasion of AH109A in vitro in a dose dependent manner. When rat serum obtained 0.5 h after oral intubation of green tea extract was added to the culture media instead of newborn bovine serum at a concentration of 10%, the invasion of AH109A was significantly inhibited as compared to control rat serum (before green tea extract intubation); the inhibitory effect lasted for 1 h and disappeared 3 h after oral intubation of green tea extract, but those rat sera showed no inhibition of AH109A proliferation. These results suggest that green tea extract has an inhibitory effect on the invasion of AH109A both in vitro and ex vivo, but on the proliferation of AH109A only in vitro, and that these assay systems are effective for the screening of food components which inhibit tumor cell proliferation and invasion.

Host proteolytic activity is necessary for infectious bursal disease virus capsid protein assembly

In many viruses, a precursor particle, or procapsid, is assembled and undergoes massive chemical and physical modification to produce the infectious capsid. Capsid assembly and maturation are finely tuned processes in which viral and host factors participate. We show that the precursor of the VP2 capsid protein (pVP2) of the infectious bursal disease virus (IBDV), a double-stranded RNA virus, is processed at the C-terminal domain (CTD) by a host protease, the puromycin-sensitive aminopeptidase (PurSA). The pVP2 CTD (71 residues) has an important role in determining the various conformations of VP2 (441 residues) that build the T = 13 complex capsid. pVP2 CTD activity is controlled by co- and posttranslational proteolytic modifications of different targets by the VP4 viral protease and by VP2 itself to yield the mature VP2-441 species. Puromycin-sensitive aminopeptidase is responsible for the peptidase activity that cleaves the Arg-452-Arg-453 bond to generate the intermediate pVP2-452 polypeptide. A pVP2 R453A substitution abrogates PurSA activity. We used a baculovirus-based system to express the IBDV polyprotein in insect cells and found inefficient formation of virus-like particles similar to IBDV virions, which correlates with the absence of puromycin-sensitive aminopeptidase in these cells. Virus-like particle assembly was nonetheless rescued efficiently by coexpression of chicken PurSA or pVP2-452 protein. Silencing or pharmacological inhibition of puromycin-sensitive aminopeptidase activity in cell lines permissive for IBDV replication caused a major blockade in assembly and/or maturation of infectious IBDV particles, as virus yields were reduced markedly. PurSA activity is thus essential for IBDV replication.

Inhibitory effect of ascorbic Acid on the proliferation and invasion of hepatoma cells in culture

Effect of ascorbic acid (AsA) on the proliferation and invasion of rat ascites hepatoma AH109A cells was investigated by measuring [(3)H]thymidine incorporation into acid-insoluble fraction of the cells and by co-culturing the hepatoma cells with rat mesentery-derived mesothelial cells, respectively. AsA suppressed the invasion of AH109A cells in a dose-dependent manner at concentrations of 62.5-500 muM, while it inhibited the proliferation of the cells at higher concentrations of 250 and 500 muM. Hepatoma cells previously cultured with hypoxanthine (HX) and xanthine oxidase (XO) or with hydrogen peroxide showed increased invasive activities. AsA suppressed the reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with AsA, HX and XO or with AsA and hydrogen peroxide. Furthermore, AsA reduced the intracellular peroxide levels in AH109A cells. These results suggest that the antioxidative property of AsA may be involved in its anti-invasive action on hepatoma cells.

Bone metastasis: mechanisms and therapeutic opportunities

The skeleton is one of the most common sites for metastatic cancer, and tumors arising from the breast or prostate possess an increased propensity to spread to this site. The growth of disseminated tumor cells in the skeleton requires tumor cells to inhabit the bone marrow, from which they stimulate local bone cell activity. Crosstalk between tumor cells and resident bone and bone marrow cells disrupts normal bone homeostasis, which leads to tumor growth in bone. The metastatic tumor cells have the ability to elicit responses that stimulate bone resorption, bone formation or both. The net result of these activities is profound skeletal destruction that can have dire consequences for patients. The molecular mechanisms that underlie these painful and often incurable consequences of tumor metastasis to bone are beginning to be recognized, and they represent promising new molecular targets for therapy.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

Biology of human cutaneous melanoma

A review of the natural behavior of cutaneous melanoma, clinical and pathological factors, prognostic indicators, some basic research and the present and possible futuristic strategies in the management of this disease are presented. While surgery remains to be the most effective therapeutic approach in the management of early primary lesions, there is no standard adjuvant therapy after surgical resection, or for metastatic disease.