Nucleolar organizer regions in aggressive and nonaggressive basal cell carcinoma of the skin

Article Abstract:

Ribosomes are complicated structures of RNA and protein necessary for the translation of messenger RNA molecules into proteins. The pieces of a ribosome are assembled in the cell nucleus and then transferred to the cell's cytoplasm before assembly into the protein-producing machinery. Within the nucleus, the ribosomal subunits are manufactured within a structure called the nucleolus; within the nucleolus is the DNA required for the transcription of the RNA necessary for the ribosome. These stretches of DNA and their associated proteins are called the nucleolar organizing regions. These regions are often studied using electron microscopy. The nucleolus itself is large enough to be visible under the light microscope, however, and special staining techniques have been found which make possible the visualization of the nucleolar organizing regions, although it is generally not possible to distinguish every nucleolar organizing region individually. These special staining techniques, which rely upon the affinity of proteins for silver, are collectively called the argyrophilic staining of nucleolar organizing region (AgNOR). AgNOR has now been used to evaluate differences in basal cell carcinomas of the skin which may contribute to the likelihood of cancer invasiveness. Twenty-two specimens of basal cell carcinoma of the skin, a very common form of skin cancer, were examined; in 11 cases the cancer was nonaggressive, and in 11 cases the cancer had recurred, metastasized, or both. Counting the number of discernable nucleolar organizing regions, researchers found that the average for the nonaggressive cancers was 6.56 and the average of the aggressive basal cell cancers was 9.48. This statistically significant difference may prove useful in the identification of patients at higher risk for cancer recurrence or disease spread. (Consumer Summary produced by Reliance Medical Information, Inc.)

Cancer invasiveness, Skin cancer, Nucleolus organizer region

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Characterization of epidermal growth factor receptor in normal and neoplastic human endometrium

Article Abstract:

Growth factors are protein compounds that attach to specific cell membrane sites called receptors and activate the growth of cells. One type of growth factor, epidermal growth factor (EGF), consists of 53 amino acids in a single chain-like arrangement with sulphur-hydrogen bonds. EGF has been shown to activate a series of biochemical reactions leading to the production of DNA, which carries the genetic code, and to mitosis, or cell division. Under certain conditions, EGF can inhibit the growth of cells. Previous studies have suggested a role for growth factors, including EGF, in the growth of certain types of cancer. The presence of EGF receptors was assessed in normal and cancerous endometrium, the mucous membrane lining the inner surface of the uterus. Tissue was removed by surgery and the endometrial membranes were isolated. Radioreceptor assays to determine the amount and characteristics of receptors showed the presence of EGF receptors with a dissociation constant of 0.64 nanomoles per liter in normal endometrium. The dissociation constant is a characteristic of the receptor that reflects the degree to which the ligand or binding molecule interacts with its specific receptor. The molecular weight of the receptor, a measure of the mass of a molecule, ranged from 150 to 170 kiloDaltons (KD). Examination of 37 tissue samples revealed a decrease in the numbers of receptors with increasing grade of cancer. However, the dissociation constant and molecular weight of the EGF receptor did not differ between normal and cancerous endometrium. These findings suggest that hormones and/or growth factors may decrease the number of EGF receptors. (Consumer Summary produced by Reliance Medical Information, Inc.)

Endometrial cancer, Epidermal growth factor, Epidermal growth factors

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Abnormal expression of G71 antibody at the epidermal basement membrane in basal cell carcinoma

Article Abstract:

A monoclonal antibody, designated G71, has been developed that recognizes an antigen in the basement membrane zone of human epithelial tissue, including normal skin. Since intact basement membrane is thought by some to provide a physical barrier against the invasion of tumor cells, the expression of G71 antigen on basement membrane was investigated in a number of different tumors by immunohistochemical staining. G71 was found to be absent or reduced surrounding 44 basal cell carcinomas tested. The antigen was present, however, in 18 squamous cell carcinomas. The staining pattern was normal in other conditions tested, including keratoacanthomas, solar keratoses, seborrheic keratoses, and intraepidermal squamous cell carcinoma. Why the antigen is absent in the basal cell carcinomas is not clear, and it is uncertain whether its absence represents a decreased production or an increased degradation. However, the lack of changes of G71 antigen in squamous cell carcinoma suggests that destruction of the basement membrane is not a prerequisite for successful invasion of tumor cells. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Skin, Monoclonal antibodies, Membrane, Basement, Basement membrane

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