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iConcept Journal of Emerging Issues in Medical Diagnosis and Treatment
Title
iConcept Journal of Emerging Issues in Medical Diagnosis and Treatment
Editor
Eugenia Giannopoulou
ISSN
2309-3528
Publisher
iConcept Press

iConcept Journal of Emerging Issues in Medical Diagnosis and Treatment

Perspectives in Tumour Biology: Tumour Differentiation and Insights Into Embryogenesis

by Bhanu Iyengar

Volume: 2 (2013); Issue: 13
Status: Copy Editing and Typesetting

Abstract

Molecular aspects of the common pathways linking embryogenesis and oncogenesis have been well studied, protooncogenes and oncogenes playing a crucial role during proliferation in both situations. Briefly, transformation of proto-oncogenes into oncogenes leads to growth promotion and regulation in normal cells, during embryogenesis, but are typically \"turned off\" in adults. In carcinogenesis, genetic damage with DNA alterations leads to point mutations of genes, translocations of genetic material between chromosomes, and gene reduplication with amplification resulting in transformation of proto-oncogenes into oncogenes. Neoplasia, or uncontrolled cellular proliferation, can result either from mutations that \"turn on\" the oncogenes that stimulate growth, or from mutations that result in loss of tumor suppressor genes and their products that inhibit growth. Both embryogenesis and oncogenesis show intense proliferative activity with changing patterns of differentiation. In the present work, cellular patterns, cell interactions and behavior, of tumor growth and embryogenesis at different levels of differentiation, are compared, to get insights into these two very similar processes giving such drastically different outcomes. Included are: Germ cell tumors; Embryomas: Ectodermal and neuroectodermal tumors including melanomas. Special emphasis is on melanomas and neuroectodermal tumors and comparisons with early neurogenesis. Germ cell tumors: Ovarian and testicular tumors Patterns of differentiation show the formation of axis and directional differentiation to be due to the male component functioning upto 4 to 8 cell embryos, whereas the further differentiation to be contributed by the female. Placental and endodermal sinus tumors provide insights into invasive growth. Neural tube formation: Once directional development begins the ectoderm infolds to form the neural tube which separates from the surface ectoderm. Zones of high embryonal induction are reflected by the higher neuroectodermal and ectodermal tumor incidence in children and adults. Embryomas: Tumors arising in early childhood, depict patterns of differentiation seen during organogenesis as in neuroblastomas and other neuroectodermal tumors, Wilm’s tumor from renal analage, hepatoblastomas and others. Clues from skin tumors – Steps of differentiation of skin and adnexa are delineated by the basal cell carcinoma and skin adnexal tumors, each level giving rise to a distinct tumor type. Primitive neuroectodermal patterns within these remind one of common ancestry of the nervous system and skin. Cells from the neural crest migrate and differentiate into melanocytes to link with the keratinocytes in the epidermis. These form combined lesions. Melanocyte-keratinocyte interactions are well brought out in pigmented basal cell carcinoma, seborrheic keratosis, psoriasis and lichen planus. Melanocytes show dendritic extensions in response to biophoton UV emissions from mitotic basal cells being much like axonal growth reflecting the possible role in axonal growth and plasticity during embryogenesis. Melanomas: Embryonal neurogenesis is well spelt out during tumor vascular interaction in melanomas. Differentiation of biogenic-aminergic and hormone producing neurons are clarified. The self propagating system of vasculature in amelanotic melanomas is reminiscent of embryonal vasculogenesis.

Author Details

Bhanu Iyengar
Pigment Cell Center

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