Cytogenetic Alterations During Malignant Transformation
Interest in the degree of chromosomal stability of normal cells in vitro and in the same cells under conditions leading to “malignant transformation” obviously relates to various theories of cancer which can be assembled under the term “somatic mutation.” Only in the past 7 or 8 years have techniques been available for adequate studies of mammalian chromosomes. The comments of Schultz (18) are appropriate in this regard: “It is a truism by now that the change from the normal to the neoplastic cell must involve a change in cellular heredity. However, this statement is now so general as to be meaningless; it demands a rephrasing in concrete terms and a more definite conceptual analysis.” Schultz pointed out that alternative hypotheses often consist of nothing more than restatements “specified in terms of a particular phenotype” which also applies to the viral theory of tumorigenesis. The virus may act only at one point during infection and its subsequent loss would be immaterial since it functions as an initiator, an agent of gene or structural mutation. Viral DNA may possibly become incorporated into the mammalian host cell genome in the manner of lysogenic systems but again this can be classified as a special case of a somatic cell mutation.
KeywordsMigration Attenuation Defend Measle Papilloma
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