CLONING AND SEQUENCING OF HUMAN BETA(III)-TUBULIN CDNA - INDUCTION OFBETA(III) ISOTYPE IN HUMAN PROSTATE CARCINOMA-CELLS BY ACUTE EXPOSURETO ANTIMICROTUBULE AGENTS

Antimicrotubule drugs are used as chemotherapeutic agents due to their effects on essential cellular functions such as mitosis, organelle tr ansport and maintenance of cell shape. When used in combination, pacli taxel with estramustine or vinblastine has demonstrated activity again st hormone refractory prostate cancer. To understand the mechanism of resistance that develops in patients as a result of antimicrotubule dr ug therapy, we exposed human prostate carcinoma cells to IC20 and IC40 doses of estramustine, paclitaxel or vinblastine for 48 h and examine d the P-tubulin (the cellular target) isotype composition. The results revealed an increase in the beta(III)-tubulin isotype as a result of drug treatment both at protein and message levels. In addition, examin ation of human brain cell lines with different intrinsic levels of bet a(III) showed that cell lines with higher beta(III) levels were more r esistant to paclitaxel. These results are in agreement with our previo us findings in human prostate carcinoma cell lines that were made resi stant to estramustine or paclitaxel and suggest an important function for beta(III) in antimicrotubule drug resistance. Also, the complete c oding sequence of human beta(III) tubulin reported here will provide m olecular tools for future investigations. (C) 1998 Elsevier Science B. V.