Vincristine‐resistant Human Cancer KB Cell Line and Increased Expression of Multidrug‐resistance Gene

Abstract

A multidrug‐resistant clone of human cancer KB cells was isolated by stepwise selection on exposure to increasing doses of vincristine. The final clone, VJ‐300, obtained after ethylmethane sulfonate mutagenesis showed 400‐fold higher resistance to vincristine than did KB cells. Cellular accumulation of vincristine in VJ‐300 was decreased to less than one‐tenth of that in KB. The cells were also cross‐resistant to daunomycin, adriamycin, actinomycin D, colchicine and VP‐16. During continuous culturing in the absence of any drug for several months, a different colchicine‐resistant and multidrug‐resistant clone, KB‐C1, reverted almost completely to drug sensitivity, whereas drug resistance in VJ‐300 was stably maintained. Amplification of the multidrug‐resistance‐1 (mdr‐1) gene was more than 20‐fold in KB‐C1, but less than 2‐fold in VJ‐300, mdr‐1 mRNA was, however, expressed in VJ‐300 at a rate comparable to KB‐C1. Acquisition of high multidrug resistance in VJ‐300 might be correlated with both activated transcription of mdr‐1 gene and amplification.

Expression of multidrug resistance-associated protein (MRP), MDR1 and DNA topoisomerase II in human multidrug-resistant bladder cancer cell lines

“…The accumulation of vincristine is often decreased in cancer cell lines overexpressing P-gp or the MDRl gene, and is consistent with the findings of our previous study (Nakagawa et al, 1986;Shiraishi et al, 1987;Kohno et al, 1988). A decreased accumulation of etoposide was observed in bladder cancer cell lines overexpressing the MRP gene or its product.…”

“…Figure 4b, Table II). The cellular MDR1 mRNA level in KK47/ ADM cels was similar to that of a multidrug-resistant ceUl line, VJ-300, which overexpresses P-gp, derived from human epidermoid cancer KB ceUls (Kohno et al, 1988) (Cole et al, 1992;Grant et al, 1994), the MRP-specific probe hybridised to 6.5 kb RNA species (Figure 4b Figure 4a and b.…”

“…Cellular accumulation of vincristine, etoposide and doxorubicin The cellular accumulation of vincristine, etoposide and doxorubicin is often reduced in multidrug-resistant cell lines (Kohno et al, 1988;Matsuo et al, 1990 Doxorubicin accumulation in T24, T24/ADM-2 and T24/ VCR cells was compared using fluorescence microscopy. As seen in Figure 3a, doxorubicin accumulated in the nuclei of T24 cells when incubated for 40 min with the drug.…”

Chemosensitisation of spontaneous multidrug resistance by a 1,4-dihydropyridine analogue and verapamil in human glioma cell lines overexpressing MRP or MDR1

“…The cellular accumulation of vincristine, etoposide and doxorubicin is often reduced in multidrug-resistant cell lines (Kohno et al, 1988;Matsuo et al, 1990). The reduced accumulation of etoposide appears to be involved in the relatively higher drug resistance of T98G (Abe et al, 1994a).…”

A YAC-based contig of 1.5 Mb spanning the human multidrug resistance gene region and delineating the amplification unit in three human multidrug-resistant cell lines.

“…The vincristine-resistant sublines, Kst-VlO0 and Kst-V500, were isolated by increasing the concentration of vincristine in the selection media to 100 or 500 ng/ml (Nacalai Tesque, Inc., Kyoto, Japan), respectively (Kohno et al 1994). Cells were grown as described previously (Kohno et al 1988(Kohno et al , 1994.…”