Syed Mulazim Hussain Bukhari, Shahzad S Q, Samina Naeem, Qureshi G R, Naveed L A.
Role of Chemical Carcinogens in Epithelial and Mesenchymal Neoplasms with Tumor Initiation-Promotion Protocol and the effect of 13-Cis retinoic acid IN CHEMOPREVENTION.
J Coll Physicians Surg Pak Jan ;12(5):302-6.

Objective: To study the effects of chemical carcinogens on epithelial and mesenchymal tumorigenesis with tumor initiation-promotion protocol and the use of 13-cis retinoic acid as a chemopreventive agent. Design: It was an experimental study. Place and Duration of Study: The study was conducted at Postgraduate Medical Institute (PGMI) Lahore for 20 weeks. Materials and Methods: Sixty albino rats were divided into six groups of ten animals each. First group of animals (control) was not given carcinogens and 13-cis retinoic acid in second group DMBA was applied on the dorsal skin in repeated dose of 100mcg/ml in acetone, twice a week. In the third group DMBA was given 100mcg/ml as single dose while TPA was given 10mcg/ml in acetone, twice a week after two weeks of DMBA application. In fourth group only DMBA 100mcg/ml in acetone was applied as a single dose. In fifth and sixth groups 13-cis retinoic acid was given topically before and after the application of DMBA and TPA. Results: First and fourth groups did not develop any tumor. In second group 2 animals developed malignant fibrous histiocytoma, 4 squamous cell carcinoma while 1 dysplasia and 1 carcinoma in situ. Third group developed osteoma (3 animals), papilloma (3 animals), squamous cell carcinoma (01) and dysplasia (01). Conclusion: Our results showed that DMBA acts as tumor initiator while TPA as promoter. DMBA also produces tumors itself when given alone in repeated doses. The chemical carcinogens are not only a cause of epithelial carcinogenesis but also responsible for mesenchymal tumorigenesis. 13-cis retinoic acid was equally effective in both stages of tumorigenesis. It also prevents malignant conversion of chemically induced benign tumors.

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