Basal-cell carcinoma
Basal-cell carcinoma (BCC), also known as basal-cell cancer, is the most common type of skin cancer. It often appears as a painless raised area of skin, which may be shiny with small blood vessels running over it; or it may present as a raised area with ulceration. Basal-cell cancer grows slowly and can damage the tissue around it but is unlikely to spread to distant areas or to result in death.
Risk factors include exposure to ultraviolet light, having lighter skin, radiation therapy, long-term exposure to arsenic, and poor immune-system function. Exposure to UV light during childhood is particularly harmful. Tanning beds have become another common source of ultraviolet radiation. Diagnosis often depends on skin examination, confirmed by tissue biopsy.
It remains unclear whether sunscreen affects the risk of basal-cell cancer. Treatment is typically by surgical removal. This can be by simple excision if the cancer is small; otherwise Mohs surgery is generally recommended. Other options may include application of cold, topical chemotherapy, laser surgery, or the use of imiquimod. In the rare cases in which distant spread has occurred, chemotherapy or targeted therapy may be used.
Basal-cell cancer accounts for at least 32% of all cancers globally. Of skin cancers other than melanoma, about 80% are basal-cell cancers. In the United States, about 35% of white males and 25% of white females are affected by BCC at some point in their lives.
Individuals with a basal-cell carcinoma typically present with a shiny, pearly skin nodule. However, superficial basal-cell cancer can present as a red patch similar to eczema. Infiltrative or morpheaform basal-cell cancers can present as a skin thickening or scar tissue – making diagnosis difficult without using tactile sensation and a skin biopsy. It is often difficult to visually distinguish basal-cell cancer from acne scar, actinic elastosis, and recent cryodestruction inflammation.
About two thirds of basal-cell carcinomas occur on sun-exposed areas of the body. One-third occur on areas of the body that are not exposed to sunlight, emphasizing the genetic susceptibility of basal-cell cancer.
P19 cell
Cancer cells in humans may result in the patient's death if the aggressive cancer cell grows and metastasizes. However, researchers utilize these cells to study the development of cancer cells in order to find more specific treatments. For developmental biologists, embryonal carcinoma, which is derived from teratocarcinoma, is a good object for developmental study. In 1982, McBurney and Rogers transplanted a 7.5 day mouse embryo into the testis to induce tumor growth. Cell cultures containing undifferentiatied stem cells were isolated from the primary tumor which have a euploid karyotype. These stem cells were named embryonal carcinoma P19 cells. These derived P19 cells grew rapidly without feeder cells and were easy to maintain. Moreover, the multipotency of P19 cells was then confirmed by injecting the cells into blastocysts of another mouse strain. The researchers found that there were tissues from all three germ layers growing in the recipient mouse. Based on their continuous studies, they further derived subtype cell lines from original P19 cells: P19S18, P19D3, P19RAC65 and P19C16. The difference between these subtype cell lines is the ability to differentiate into neuronal cells or muscle cells in response to treatment with retinoic acid or DMSO, respectively.
More recently, various studies generate cell lines that were initially derived from differentiated P19 cells. Due to the pluripotency of P19 cells, those new derived cell lines can be ectoderm, mesoderm and endoderm-like cells.