B16 melanoma is a murine tumor cell line used for research as a model for human skin cancers. B16 cells are useful models for the study of metastasis and solid tumor formation, and were one of the first effective murine tools for metastasis research. These cells readily metastasize to lymph nodes and lungs. The black melanin pigment they produce facilitates easy visualization of metastatic colonies in these organs. [1]
B16 cells were discovered and maintained in the Jackson Laboratories in Maine in 1954 when a tumor developed naturally behind the ear of a C57BL/6 mouse. [2] The cells were resected, transplanted, and maintained in vivo, and still are today.
B16 models were in use to an extent in the 1970s, but it was Dr. Isaiah J. Fidler, a Jerusalem-born, Oklahoma State-trained veterinarian, and University of Pennsylvania-trained biological researcher, now at M.D. Anderson Cancer Center in Houston, Texas, who established solid protocols for use the B16 model. [3] One of his first major studies involving B16 was in 1970. Dr. Fidler stained B16s, having cultured them in vitro, with 125I-5-iodo-2′-deoxyuridine for tracking, and implanted the cells into C57BL/6J mice, the common host, sacrificed the mice at different times, and measured the cells in the blood and in different organs. [4] He ascertained that 99% of the original cell population had perished within a day, and that a cohort of about 400 cells had colonized the lung. The study was seminal because it established the existence of a reliable metastasis pathway that was uncomplicated to perturb and view changes. It also showed that metastasis is not guaranteed simply by the presence of tumor cells. Only a certain few are able to circulate and latch on to the right organ and begin to form a tumor.
In the 1980s it was discovered that B16 cells express very low levels of mouse class I major histocompatibility complex glycoproteins, H-2Kb and H-2Db, [5] and that in vitro treatment with gamma interferon simultaneously induced a high expression of H-2 and an increase in the metastatic potential of B16 cells. [6]
B16 cells originate in melanin-producing epithelia of mice, and are easy to track in vivo post-transplantation. Their fidelity of metastasis from skin to lung, liver, and spleen makes them useful and predictable tools to study metastatic pathways. [7] [8]
In the 1962 edition of the Handbook of Genetically Standardized Jax Mice, the cells were described thus: [9]
Gross: soft gray tissue, frequently hemorrhagic. Microscopic: tumor cells polyhedral or spindle-shaped, arranged in perivascular mantles and diffuse masses; some cells contain fine pigmented granules, a few are obscured by large, very dark globules of pigment; stoma delicate and vascular. Pigment greatly decreased in comparison with early transplant generation.
Varying surface proteins were shown to play an important part in the locative destiny of the cells on which they are affixed. [10] [11] The presence of high numbers of particular proteins correspond to a cell's affinity for particular organs was selected for in many of the lines perpetuated in labs in the seventies and eighties. Tumor cells from lungs, for instance, would be harvested from a deceased mouse and transplanted into another mouse's skin, and that mouse, upon death, would have its resultant lung tumors transplanted to the next mouse, and so on. Over time, cells in that line injected into the skin would almost always become lung tumors. The same directed etiology, moreover, has been undertaken for many other organs, leading to separate sub-lines with titles such as B16-F10, B16-BL6, B164A5, B16GMCSF, and B16FLT3.
Today, B16 melanoma remains indispensable for metastasis studies. Current research projects focus on the cells’ immunological response to vaccines, microRNA mediated metastatic properties, especially miR-21, a noted aggressor of tumor suppressors and anti-proliferative factors. [12] [13] B16 is also used as a pre-clinical model to study immunotherapy. [14] Those are just a few examples, but the undergirding idea is that the B16 melanoma model is a powerful research tool, and a staple for metastasis studies, and its development as such can be considered a huge benefit to the cancer research community. [2]
Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, are metastases (mets). It is generally distinguished from cancer invasion, which is the direct extension and penetration by cancer cells into neighboring tissues.
Cutaneous squamous-cell carcinoma (cSCC), also known as squamous-cell carcinoma of the skin or squamous-cell skin cancer, is one of the three principal types of skin cancer, alongside basal-cell carcinoma and melanoma. cSCC typically presents as a hard lump with a scaly surface, though it may also present as an ulcer. Onset and development often occurs over several months. Compared to basal cell carcinoma, cSCC is more likely to spread to distant areas. When confined to the epidermis, the outermost layer of the skin, the pre-invasive or in situ form of cSCC is termed Bowen's disease.
Melanoma is the most dangerous type of skin cancer; it develops from the melanin-producing cells known as melanocytes. It typically occurs in the skin, but may rarely occur in the mouth, intestines, or eye. In women, melanomas most commonly occur on the legs; while in men, on the back. Melanoma is frequently referred to as malignant melanoma. However, the medical community stresses that there is no such thing as a 'benign melanoma' and recommends that the term 'malignant melanoma' should be avoided as redundant.
Cancer stem cells (CSCs) are cancer cells that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample. CSCs are therefore tumorigenic (tumor-forming), perhaps in contrast to other non-tumorigenic cancer cells. CSCs may generate tumors through the stem cell processes of self-renewal and differentiation into multiple cell types. Such cells are hypothesized to persist in tumors as a distinct population and cause relapse and metastasis by giving rise to new tumors. Therefore, development of specific therapies targeted at CSCs holds hope for improvement of survival and quality of life of cancer patients, especially for patients with metastatic disease.
Uveal melanoma is a type of eye cancer in the uvea of the eye. It is traditionally classed as originating in the iris, choroid, and ciliary body, but can also be divided into class I and class II. Symptoms include blurred vision, loss of vision or photopsia, but there may be no symptoms.
Actibind is an actin-binding fungal T(2)-RNase protein that is produced by the black mold Aspergillus niger, a microorganism used in biotechnology and food technology. In plants, actibind binds actin, a major component of the cytoskeleton, interfering with the plants' pollen tubes and halting cell growth. Research published in the journal Cancer on 15 May 2006 reports evidence that actibind has antiangiogenic and anticarcinogenic characteristics. In human colon cancer, breast cancer and melanoma, increasing the level of actibind was found to reduce the ability of these cells to form tumorogenic colonies. In animal models, increased actibind inhibited the growth of colon cancer-derived tumors, metastases and blood vessel formation. During the completion of the Human Genome Project, the gene encoding for RNaseT2, the human actibind-like protein, was found on chromosome 6.
Ipilimumab, sold under the brand name Yervoy, is a monoclonal antibody medication that works to activate the immune system by targeting CTLA-4, a protein receptor that downregulates the immune system.
Melanocyte protein PMEL also known as premelanosome protein (PMEL), silver locus protein homolog (SILV) or Glycoprotein 100 (gp100), is a protein that in humans is encoded by the PMEL gene. Its gene product may be referred to as PMEL, silver, ME20, gp100 or Pmel17.
A metastasis suppressor is a protein that acts to slow or prevent metastases from spreading in the body of an organism with cancer. Metastasis is one of the most lethal cancer processes. This process is responsible for about ninety percent of human cancer deaths. Proteins that act to slow or prevent metastases are different from those that act to suppress tumor growth. Genes for about a dozen such proteins are known in humans and other animals.
Transcription factor 21 (TCF21), also known as pod-1, capsuling, or epicardin, is a protein that in humans is encoded by the TCF21 gene on chromosome 6. It is ubiquitously expressed in many tissues and cell types and highly significantly expressed in lung and placenta. TCF21 is crucial for the development of a number of cell types during embryogenesis of the heart, lung, kidney, and spleen. TCF21 is also deregulated in several types of cancers, and thus known to function as a tumor suppressor. The TCF21 gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.
Adoptive cell transfer (ACT) is the transfer of cells into a patient. The cells may have originated from the patient or from another individual. The cells are most commonly derived from the immune system with the goal of improving immune functionality and characteristics. In autologous cancer immunotherapy, T cells are extracted from the patient, genetically modified and cultured in vitro and returned to the same patient. Comparatively, allogeneic therapies involve cells isolated and expanded from a donor separate from the patient receiving the cells.
A brain metastasis is a cancer that has metastasized (spread) to the brain from another location in the body and is therefore considered a secondary brain tumor. The metastasis typically shares a cancer cell type with the original site of the cancer. Metastasis is the most common cause of brain cancer, as primary tumors that originate in the brain are less common. The most common sites of primary cancer which metastasize to the brain are lung, breast, colon, kidney, and skin cancer. Brain metastases can occur months or even years after the original or primary cancer is treated. Brain metastases have a poor prognosis for cure, but modern treatments allow patients to live months and sometimes years after the diagnosis.
Lewis lung carcinoma is a hypermutated Kras/Nras–mutant cancer with extensive regional mutation clusters in its genome. A tumor that spontaneously developed as an epidermoid carcinoma in the lung of a C57BL mouse. It was discovered in 1951 by Dr. Margaret Lewis of the Wistar Institute and became one of the first transplantable tumors.
Skin cancer, or neoplasia, is the most common type of cancer diagnosed in horses, accounting for 45 to 80% of all cancers diagnosed. Sarcoids are the most common type of skin neoplasm and are the most common type of cancer overall in horses. Squamous-cell carcinoma is the second-most prevalent skin cancer, followed by melanoma. Squamous-cell carcinoma and melanoma usually occur in horses greater than 9-years-old, while sarcoids commonly affect horses 3 to 6 years old. Surgical biopsy is the method of choice for diagnosis of most equine skin cancers, but is contraindicated for cases of sarcoids. Prognosis and treatment effectiveness varies based on type of cancer, degree of local tissue destruction, evidence of spread to other organs (metastasis) and location of the tumor. Not all cancers metastasize and some can be cured or mitigated by surgical removal of the cancerous tissue or through use of chemotherapeutic drugs.
Nivolumab, sold under the brand name Opdivo, is an anti-cancer medication used to treat a number of types of cancer. This includes melanoma, lung cancer, malignant pleural mesothelioma, renal cell carcinoma, Hodgkin lymphoma, head and neck cancer, urothelial carcinoma, colon cancer, esophageal squamous cell carcinoma, liver cancer, gastric cancer, and esophageal or gastroesophageal junction cancer. It is administered intravenously.
Patient derived xenografts (PDX) are models of cancer where the tissue or cells from a patient's tumor are implanted into an immunodeficient or humanized mouse. It is a form of xenotransplantation. PDX models are used to create an environment that allows for the continued growth of cancer after its removal from a patient. In this way, tumor growth can be monitored in the laboratory, including in response to potential therapeutic options. Cohorts of PDX models can be used to determine the therapeutic efficiency of a therapy against particular types of cancer, or a PDX model from a specific patient can be tested against a range of therapies in a 'personalized oncology' approach.
Breast cancer metastatic mouse models are experimental approaches in which mice are genetically manipulated to develop a mammary tumor leading to distant focal lesions of mammary epithelium created by metastasis. Mammary cancers in mice can be caused by genetic mutations that have been identified in human cancer. This means models can be generated based upon molecular lesions consistent with the human disease.
Axelopran is a drug which is under development by Theravance Biopharma and licensed to Glycyx for all indications. It acts as a peripherally acting μ-opioid receptor antagonist and also acts on κ-, and δ-opioid receptors, with similar affinity for the μ- and κ-opioid receptors and about an order of magnitude lower affinity for the δ-opioid receptor. Recent data suggests that μ-opioid antagonists have a direct effect on overall survival in patients with advanced cancer.
4T1 is a breast cancer cell line derived from the mammary gland tissue of a mouse BALB/c strain. 4T1 cells are epithelial and are resistant to 6-thioguanine. In preclinical research, 4T1 cells have been used to study breast cancer metastasis as they can metastasize to the lung, liver, lymph nodes, brain and bone. The cells are known to be highly aggressive in live tissues.
Yona Keisari is an Israeli Immunologist and cancer researcher, professor emeritus at the Department of Microbiology and Clinical Immunology in the Faculty of Medical and Health Sciences, Tel Aviv University. An expert in the field of immunology of cancerous tumors, and co-founder of the radiotherapy company "Alpha Tau Medical".