G. Barry Pierce

Differentiation and cancer

SummaryCancer is discussed from a standpoint of a postembryonic differentiation. A differentiation requires the interaction of an exogenous inductive stimulus with competent precursor cell, which then evolve a new tissue with unique, stable heritable properties distinguishable from the progenitor. Evidence is cited pinpointing the normal stem cells of tissues as the competent target precursor cells in carcinogenesis. The resultant phenotype differs from its progenitor and has stable and unique characteristics. All of the characteristics associated with malignancy are expressed during some stage of development, suggesting that the normal genome contains the information necessary for malignant expression, and that the mechanism of malignancy is probably an alteration of control of genomic expression.Malignant tissue, like normal tissue, maintains itself by proliferation and differentiation of its stem cells; at least, that is what was observed in two tumors examined. In each of these tumors the differentiated progeny of the malignant stem cells proved to be benign.A third tumor was adapted to growth in vitro and under the conditions of the experiments could be modulated by altering the in vitro conditions. These data suggest that direction of the naturally occurring differentiation that occurs in tumors may be a suitable therapeutic alternative to cytotoxic chemotherapy.

Changes in antigenicity of basement membrane during wound healing.

Abstract The healing of cutaneous wounds of mice was examined by immunofluorescent, phase, and electron microscopy. The results suggested that the epithelial basement membrane appeared to undergo degradation early in the healing process and did not regain all characteristics until remodeling of the redundant epidermis was completed. It did not appear to function as a substratum for epithelial migration; instead it appeared that the basement membrane may be partially responsible for the maintenance of the microenvironment of the epidermis. Phase micrographs illustrated a large number of degenerating basal cells at the completion of reepithelialization. These cells were confined to the basal layer and suggested that wound remodeling was initiated by selective cell death.

Cancer Cells as Probes of Embryonic Development

Five embryonic fields have been shown to regulate appropriate carcinomas. Specificity for the reaction has been established in two of these fields, suggesting that a close developmental correspondence between the field and the cancer cell is required- Inhibitors of mitosis are present in two of these embryonic fields, and in one case it is likely that the inhibitor plus cell contact is required for regulation to occur.