objective:
To induce tolerance to hexadecylphosphocholine(HePC) in human epidermoid tumour cell line
KB with
gradually increasing
concentration of HePC. To study the characteristic of the
resistance subline KBr cells. Methods: KB cells were adapted to HePC starting from low
concentration of HePC, the concentration of HePC was raised gradually until the KB cells had
obvious resistance to it.MTT assay was used for test of cross resistance to chemotherapeutics
agents in KBr cells.The
expression of mdr1,mrp and GSTpi gene was determined by RTPCR.
Immunocytochemistry was used for expression of Pglycoprotein(Pgp).ZResults: KB cells were
adapted to HePC starting from a concentration at 004 mol/L. When the cells tolertated to HePC
and showed normal growth and high viability, the concentration of HePC was raised
accordingly.The adaptation was stopped when the concentration of HePC reached to 45 mol/L,
cells had obvious resistance to HePC. MTT assay showed the KBr cells had 32fold higher IC50
of HePC than parental KB cells.KBr cells also had significant resistance to vincristine and
colchicine although KBr cells were still sensitive to mechlorethamine,carmustine,actinomycin
D, etoposide,doxorubicin and 5fluorouracil.The IC50 of vincristine and colchicine on KBr cells
were respectively 1354fold and 44697fold much higher than that of KB cells. Our study showed
that Kbr cells had no expression of mrp and GSTpi gene, but there were mdr1 gene and Pgp
positive expression in resistant KBr cells. Conclusion: KB cells show obvious resistance to
HePC after long term induction.The resistant subline KBr cells have cross resistance to
vincristine and colchicine.The positive expression of mdr1 and Pgp in KBr cells might be
associated with the resistance.