Metastases from metastases: comparative metastatic potential of human cancer cell lines originated from primary tumors or metastases in various tissues

Although metastases from original (primary) tumors are highly studied, metastases from metastatic sites (secondary tumors) are far less studied. Here, using data from metastasis map (MetMap) project reported in a recent study (Jin et al. in Nature 588(7837): 331–336. 10.1038/s41586-020-2969-2, 2020), we found that human cancer cell lines isolated from metastatic sites have higher potential to metastasize to another site in mice, compared to human cancer cell lines isolated from primary sites, for certain types of cancer including liver, lung and pancreas cancer. In contrast, for cancer types such as ovarian and skin cancer, human cancer cell lines originated from primary tumors have increased metastatic potential in mice, compared to human cancer cell lines originated from metastatic sites. This preliminary analysis points that the potential of metastases to further metastasize compared to that of primary tumors might be cancer type-dependent, and further research is needed to understand why certain cancer cell lines isolated from metastatic sites are more likely to spread to other organs.     

A New Mouse Model for the Study of Human Breast Cancer Metastasis

Breast cancer is the most common cancer in women, and this prevalence has a major impact on health worldwide. Localized breast cancer has an excellent prognosis, with a 5-year relative survival rate of 85%. However, the survival rate drops to only 23% for women with distant metastases. To date, the study of breast cancer metastasis has been hampered by a lack of reliable metastatic models. Here we describe a novel in vivo model using human breast cancer xenografts in NOD scid gamma (NSG) mice; in this model human breast cancer cells reliably metastasize to distant organs from primary tumors grown within the mammary fat pad. This model enables the study of the entire metastatic process from the proper anatomical site, providing an important new approach to examine the mechanisms underlying breast cancer metastasis. We used this model to identify gene expression changes that occur at metastatic sites relative to the primary mammary fat pad tumor. By comparing multiple metastatic sites and independent cell lines, we have identified several gene expression changes that may be important for tumor growth at distant sites.     

Establishment of a Chinese bladder cancer cell line (T921) with high metastatic activity

Muscle-invasive bladder cancer is prone to metastasis without a standard organ preference. The current cell lines used to study bladder cancer have primarily been derived from individuals in Western populations, and no human bladder cancer cell line has been established from the Chinese population. A bladder cancer cell line was derived from a female Chinese patient with muscle-invasive bladder cancer, and these cells were then xenografted into the bladders of three nude mice. Five weeks later, these mice were killed to observe local invasion and distant metastasis. The metastatic tumors were also removed and analyzed to assess the metastatic mechanism. This bladder cancer cell line, named T921, was successfully established, as evidenced by karyotype and immunohistochemistry analyses. Multi-organ metastases were observed in all three of the nude mice 5 wk after the orthotopic transfer of the cell line. In addition, epithelial–mesenchymal transition (EMT)-related genes were involved in the tumor metastases. The T921 bladder cancer cell line was successfully established, and EMT was observed to play a role in bladder cancer metastasis.     

Origin and biology of cancer metastasis

Metastasis, the spread of cells from a primary neoplasm to distant sites where they grow, contributes to the death of most cancer patients. The process of metastasis is not random. Rather, the process consists of a series of linked, sequential steps that must be completed by tumor cells if a metastasis is to develop. Thus, metastatic cells must succeed in invasion and embolization, survive in the circulation, arrest in a distant capillary bed, and extravasate into and multiply in organ parenchyma. Although some of the steps in this process contain stochastic elements, as a whole metastasis favors the survival and growth of a few subpopulations of cells that preexist within the parent neoplasm. Moreover, metastases can have a clonal origin, and different metastases can originate from the proliferation of single cells. The outcome of metastasis depends on the interaction of metastatic cells with different organ environments. Organ-specific metastases have been demonstrated in a variety of experimental tumor systems, and even within one organ, site-specific tumor growth can be found. The conclusion that metastasis is a highly selective process that is influenced by both the intrinsic properties of tumor cells and by host factors is optimistic. A selective process is regulated and therefore can be studied and then manipulated.     

Micrometastases in bone marrow in patients with primary breast cancer: evaluation as an early predictor of bone metastases.

The bone marrow of 307 patients with primary breast cancer was examined for tumour cells by immunocytochemistry using an antiserum to epithelial membrane antigen. Micrometastases were found in 81 cases (26.4%) and their presence was related to various poor prognostic factors: spread to lymph nodes, vascular invasion, T stage, and pathological size. The median duration of follow up was 28 months. Seventy five patients relapsed, 60 at distant sites. Of these 60 patients, 26 had micrometastases detected at presentation and 34 were free of micrometastases initially. The relapse free interval was significantly shorter for patients with micrometastases, and these patients had a shorter survival. Analysis of the sites of relapse showed that the test predicted bone metastases only. Thus 10 out of 19 patients (53%) who developed bone metastases at first relapse had micrometastases at presentation compared with only 41 out of 288 patients (14%) who remained free of bone metastases or relapsed in non-skeletal sites. The presence of micrometastases detected at the time of initial surgery in a patient with primary breast cancer is a useful predictor of early relapse in bone and may help in selecting patients for subsequent systemic treatment.     

Failure to detect intra-abdominal metastases from breast cancer: a case for staging laparotomy

Two studies were performed to assess the accuracy of non-invasive methods in detecting intra-abdominal metastases from breast cancer. Firstly, the sites of spread detected at the time of first presentation with metastases were compared with the sites of spread shown at necropsy in the same patients. Although about two-thirds of the patients with bone and lung metastases at necropsy had had metastases detected at these sites when they first presented with metastases, only a third of the patients with liver metastases and none of those with other intra-abdominal metastases had had evidence of disease at first presentation with metastases. The second study confirmed a poor detection rate of liver and other intra-abdominal metastases in patients with breast cancer undergoing laparotomy and oophorectomy who were staged immediately before operation.Pre-mastectomy staging laparotomy should be considered in those patients with primary breast cancer who are most likely to have disseminated disease beyond the regional nodes. In the presence of occult gross metastases detected by staging laparotomy, mastectomy will not provide additional protection against loca recurrence of disease. Patients with occult gross metastases should also be excluded from studies on adjuvant chemotherapy (designed to treat micrometastases). Aggressive methods of staging are justified to protect the patient as far as possible against unnecessary mastectomy and to identify those patients who should be treated by therapeutic chemotherapy rather than adjuvant chemotherapy.     

Renal epithelial proliferation and its clinical expression in Brown Norway (BN) rats

Renal epithelial proliferation has previously been found to be a common condition in a colony of Lewis x Brown Norway (BN) F2 hybrid rats. The aim of this study was to investigate the prevalence and clinical consequences of this condition in pure inbred BN and Lewis rats. Renal epithelial proliferation was found in 29 of 49 BN rats (59%) examined and in four of 50 Lewis rats (8%) examined. Serum creatinine and serum corticosterone was not influenced by the condition. Haematuria was more common in BN rats with (74%) than without renal papillary proliferation (35%, P < 0.05), but it may not be used to diagnose renal epithelial proliferation, as we found rats having renal epithelial proliferation without showing haematuria and rats showing haematuria without having renal epithelial proliferation. Haematuria was also common in Lewis rats (16-56% dependent of age and gender), in which renal epithelial proliferation were found in only 8%. Fluctuating asymmetry, which was used as a measure of developmental instability, was found to be increased in rats with renal epithelial proliferation (P < 0.05). Haematuria was also found to be related to the degree of fluctuating asymmetry (P < 0.01). Although the prevalence of renal epithelial proliferation is clearly higher in BN rats than in Lewis rats (P < 0.01), and although in previous reports the condition was found in F2 BN x Lewis hybrids and not in F1 BN x Lewis hybrids it cannot clearly be defined as having been caused by a single Mendelian gene, as we found it in both inbred strains. Futhermore, we found that morphologically the proliferations could be placed on the papillary as well as the medullary wall of the renal pelvis, while previously it has only been described on the papillary wall.     

Protein signatures associated with tumor cell dissemination in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer worldwide. Strong prognostic indicators that predict development of distant metastases are the presence and number of lymph node metastases in the neck, and extranodal spread. Recently, it was shown in several studies that also the presence of disseminated tumor cells (DTC) in the bone marrow predicts development of distant metastases. We have investigated whether protein signatures could be detected in primary HNSCC that distinguish tumors that disseminate into the bone marrow from those that do not. Therefore, DTC-positive and -negative primary HNSCC tumors were analyzed by 2D-DIGE. A signature consisting of 51 differential protein spots was identified upon stratification for bone marrow status, which allowed a correct classification of DTC-positive and DTC-negative HNSCC tumors in 95% of cases, using hierarchical clustering. The most prominent feature within this signature was the down-regulation of CK19 in DTC-positive tumors. Our data show that tumor cell dissemination to the bone marrow, the onset of hematogenic metastasis, can be deduced from the protein profile in the primary tumor. The highly significant down-regulation of CK19 supports a model of epithelial-mesenchymal transition for tumors that show a high proclivity for hematogenic dissemination.     

The validity of haematuria in the community diagnosis of urinary schistosomiasis infections

The validity and reliability of haematuria when used as screening criteria in community diagnosis of urinary schistosomiasis is presented. Between May and July, 1998, 1173 persons were screened for haematuria and examined for the presence of eggs of Schistosoma haematobium in their urine from all participating households in the Ozitem area of Bende Local Government Area, Abia State, Nigeria. Haematuria showed a sensitivity rate of 41.0% and specificity of 82.0% when used to identify cases of urinary schistosomiasis. Some factors that influenced the validity of haematuria as a diagnostic criterion are discussed. The use of haematuria amongst subjects in the first twenty years of their life is recommended.     

Adjacent thoracic lymph node metastases originating from two separate primary cancers: case report

Reported is an unusual case of adjacent thoracic lymph nodes demonstrating metastases from two different primary malignancies. A 51 year-old woman with a previous history of bilateral breast cancer underwent a radical gastro-oesophagectomy for adenocarcinoma of the lower third of the oesophagus. The resection specimen demonstrated breast and oesophageal metastases in adjacent thoracic lymph nodes. Mechanisms for this phenomenon, including the known local immune suppression on lymphoid cells by oesophageal carcinoma cells, are discussed.     

Metatarsal metastasis from transitional cell cancer of the urinary bladder

Urinary bladder cancers can be grouped into three general categories: superficial, invasive and metastatic. Approximately 90% of malignant tumors of the urinary bladder are of epithelial origin and the majority of them are transitional cell carcinomas (TCC). Metastatic spread of urinary bladder cancers usually includes regional lymph nodes, the lung, the liver and the bones. The presence of metastasis tends to correlate with muscular wall invasion as often demonstrated at the initial diagnosis; consequently clinical bladder cancer represents a late phase of the disease. Although skeletal metastases of bladder cancers are rather common, they have been rarely described to occur in distal bones. For that reason, we report metatarsal metastasis from transitional cell cancer of the urinary bladder in a 59-year-old woman.     

The cellular ratio of immune tolerance (immunoCRIT) is a definite marker for aggressiveness of solid tumors and may explain tumor dissemination patterns

The adaptive immune system is involved in tumor establishment and aggressiveness. Tumors of the ovaries, an immune-privileged organ, spread via transceolomic routes and rarely to distant organs. This is contrary to tumors of non-immune privileged organs, which often disseminate hematogenously to distant organs. Epigenetics-based immune cell quantification allows direct comparison of the immune status in benign and malignant tissues and in blood. Here, we introduce the “cellular ratio of immune tolerance” (immunoCRIT) as defined by the ratio of regulatory T cells to total T lymphocytes. The immunoCRIT was analyzed on 273 benign tissue samples of colorectal, bronchial, renal and ovarian origin as well as in 808 samples from primary colorectal, bronchial, mammary and ovarian cancers. ImmunoCRIT is strongly increased in all cancerous tissues and gradually augmented strictly dependent on tumor aggressiveness. In peripheral blood of ovarian cancer patients, immunoCRIT incrementally increases from primary diagnosis to disease recurrence, at which distant metastases frequently occur. We postulate that non-pathological immunoCRIT values observed in peripheral blood of immune privileged ovarian tumor patients are sufficient to prevent hematogenous spread at primary diagnosis. Contrarily, non-immune privileged tumors establish high immunoCRIT in an immunological environment equivalent to the bloodstream and thus spread hematogenously to distant organs. In summary, our data suggest that the immunoCRIT is a powerful marker for tumor aggressiveness and disease dissemination.     

Genetic Profiling Reveals Cross-Contamination and Misidentification of 6 Adenoid Cystic Carcinoma Cell Lines: ACC2, ACC3, ACCM,ACCNS, ACCS and CAC2

Adenoid cystic carcinoma (ACC) is the second most common malignant neoplasm of the salivary glands. Most patients survive more than 5 years after surgery and postoperative radiation therapy. The 10 year survival rate, however, drops to 40%, due to locoregional recurrences and distant metastases. Improving long-term survival in ACC requires the development of more effective systemic therapies based on a better understanding of the biologic behavior of ACC. Much preclinical research in this field involves the use of cultured cells and, to date, several ACC cell lines have been established. Authentication of these cell lines, however, has not been reported. We performed DNA fingerprint analysis on six ACC cell lines using short tandem repeat (STR) examinations and found that all six cell lines had been contaminated with other cells. ACC2, ACC3, and ACCM were determined to be cervical cancer cells (HeLa cells), whereas the ACCS cell line was composed of T24 urinary bladder cancer cells. ACCNS and CAC2 cells were contaminated with cells derived from non-human mammalian species: the cells labeled ACCNS were mouse cells and the CAC2 cells were rat cells. These observations suggest that future studies using ACC cell lines should include cell line authentication to avoid the use of contaminated or non-human cells.     

New perspectives on hereditary influences in metastatic progression

Metastasis, the process by which cancer cells spread to distant sites and form secondary tumors, depends upon the ability of cells to escape the primary tumor, and colonize and proliferate in a novel microenvironment. Many mechanisms have been proposed to explain this phenomenon although no theory has comprehensively explained all biological observations. There is growing evidence that host hereditary factors modulate the ability of tumor cells to form metastatic lesions, and host genetic polymorphism could be a significant variable in this process. This review is intended to illustrate the role of hereditary variation in metastatic progression, how this integrates with currently proposed metastatic mechanisms, and the potential clinical impact on this frequently fatal consequence of cancer.     

A haematuria diagnostic service.

In a haematuria diagnostic service, covering experience with 95 patients, 12 new cases of cancer of the bladder, one of cancer of the kidney, and one of cancer of the penis were identified--all at an early stage. Patients presenting with haematuria were investigated rapidly without disruption of the routine work of the urological unit. Patients who identified the symptoms and sought advice early were given a definite diagnosis quickly, and treatment for any malignant disease was started early. The delay that undoubtedly endangers patients'' lives has been considerably reduced by this service.     

Cancer stem cells: implications for the progression and treatment of metastatic disease

Metastasis is the major cause of death for cancer patients with solid tumours, due mainly to the ineffectiveness of current therapies once metastases begin to form. Further insight into the biology of metastasis is therefore essential in order to gain a greater understanding of this process and ultimately to develop better cancer therapies. Metastasis is an inefficient process, such that very few cells that leave a tumour successfully form macrometastases in distant sites. This suggests that only a small subset of cells can successfully navigate the metastatic cascade and eventually re-initiate tumour growth to form life-threatening metastases. Recently, there has been growing support for the cancer stem cell (CSC) hypothesis which stipulates that primary tumours are initiated and maintained by a small subpopulation of cancer cells that possess "stem-like" characteristics. Classical properties of normal stem cells are strikingly reminiscent of the observed experimental and clinical behaviour of metastatic cancer cells, including an unlimited capacity for self renewal; the requirement for a specific 'niche' or microenvironment to grow; use of the stromal cell-derived factor 1 (SDF-1)/chemokine receptor 4 (CXCR4) axis for migration; enhanced resistance to apoptosis and an increased capacity for drug resistance. Therefore, in addition to playing a role in primary tumour formation, we believe that CSCs are also key players in the metastatic process. We will review the current evidence supporting this idea and discuss the potential implications of the CSC hypothesis with regards to experimental investigation and treatment of metastatic disease.     

Atypical presentations and rare metastatic sites of renal cell carcinoma: a review of case reports

Renal cell carcinoma is a potentially lethal cancer with aggressive behavior and a propensity for metastatic spread. Due to the fact that the patterns of metastases from renal cell carcinomas are not clearly defined, there have been several reports of cases of renal cell carcinoma associated with rare metastatic sites and atypical presenting symptoms. The present review focuses on these atypical rare clinical presentations of renal cell carcinomas both at the time of diagnosis of the primary tumor but also in the years after radical nephrectomy.     

Metastasis mechanisms

Metastasis, the spread of malignant cells from a primary tumor to distant sites, poses the biggest problem to cancer treatment and is the main cause of death of cancer patients. It occurs in a series of discrete steps, which have been modeled into a “metastatic cascade”. In this review, we comprehensively describe the molecular and cellular mechanisms underlying the different steps, including Epithelial–Mesenchymal Transition (EMT), invasion, anoikis, angiogenesis, transport through vessels and outgrowth of secondary tumors. Furthermore, we implement recent findings that have broadened and challenged the classical view on the metastatic cascade, for example the establishment of a “premetastatic niche”, the requirement of stem cell-like properties, the role of the tumor stroma and paracrine interactions of the tumor with cells in distant anatomical sites. A better understanding of the molecular processes underlying metastasis will conceivably present us with novel targets for therapeutic intervention.