Linked Life Data

9287159

Source:http://linkedlifedata.com/resource/pubmed/id/9287159

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
37
pubmed:dateCreated
1997-10-14
pubmed:abstractText
Several laboratories have reported that overexpression of the multidrug resistance (MDR) protein is associated with intracellular alkalinization, and several investigators have reported that cells induced to undergo programmed cell death (apoptosis) acidify quite significantly. Because it is difficult to fully explain the resistance to apoptosis-inducing chemotherapeutic drugs that is exhibited by MDR tumor cells solely via altered drug transport alone [Hoffman et al. (1996) J. Gen. Physiol. 108, 295-313], we have investigated whether overexpression of the hu MDR 1 protein alters progression of the apoptotic cascade. LR73 fibroblasts induced to undergo apoptosis either via treatment with the chemotherapeutic drug colchicine or by serum withdrawal exhibit cellular volume changes, intracellular acidification, nuclear condensation, and chromosomal digestion ("ladder formation"), characteristic of apoptosis, in a temporally well-defined pattern. However, multidrug resistant LR73/20E or LR73/27 hu MDR 1 transfectants recently created in our laboratory without selection on chemotherapeutic drug are significantly delayed in the onset of apoptosis as defined by the above criteria, regardless of whether apoptosis is induced by colchicine treatment or by serum withdrawal. Thus, the delay cannot simply be due to the well-known ability of MDR protein overexpression to lower chemotherapeutic drug accumulation in MDR cells. LR73/27V500 "selectants", exhibiting similar levels of MDR protein overexpression but higher multidrug resistance due to selection with the chemotherapeutic drug vincristine, exhibit a slightly longer delay in the progression of apoptosis. Normal apoptotic cascade kinetics are partially restored by pre-treatment of the MDR cells with the MDR protein inhibitor verapamil. Untransfected LR73 cells not expressing MDR protein but elevated in pHi via manipulation of CO2/HCO3- as described [Hoffman et al. (1996) J. Gen. Physiol. 108, 295-313] are inhibited in DNA ladder formation, similar to LR73/hu MDR 1 transfectants. These results uncover an additional mechanism whereby MDR protein overexpression may promote the survival of tumor cells and further support the notion that in some systems intracellular acidification may be either causal or permissive for proper progression of the apoptotic cascade.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
16
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11169-78
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Human MDR 1 protein overexpression delays the apoptotic cascade in Chinese hamster ovary fibroblasts.
pubmed:affiliation
Molecular Pharmacology and Therapeutics Program at the Raymond and Beverly Sackler Foundation Laboratory, Memorial Sloan-Kettering Cancer Center, Pharmacology, Cornell University Medical College, New York, New York 10021, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't