Abstract
L-α-Difluoromethylornithine (DFMO) is a chemopreventive agent for colon cancer in clinical trials. Yet, the drug produces an across-frequency elevation of the hearing threshold, suggesting that DFMO may affect a common trait along the cochlear spiral. The mechanism for the ototoxic effects of DFMO remains uncertain. The cochlear duct is exclusively endowed with endocochlear potential (EP). EP is a requisite for normal sound transduction, as it provides the electromotive force that determines the magnitude of the receptor potential of hair cells. EP is generated by the high throughput of K+ across cells of the stria vascularis, conferred partly by the activity of Kir4.1 channels. Here, we show that the ototoxicity of DFMO may be mediated by alteration of the inward rectification of Kir4.1 channels, resulting in a marked reduction in EP. These findings are surprising given that the present model for EP generation asserts that Kir4.1 confers the outflow of K+ in the stria vascularis. We have proposed an alternative model. These findings should also enable the rational design of new pharmaceuticals devoid of the untoward effect of DFMO.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 15097-15102 |
| Number of pages | 6 |
| Journal | Journal of Biological Chemistry |
| Volume | 280 |
| Issue number | 15 |
| DOIs | |
| State | Published - Apr 15 2005 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Functional consequences of polyamine synthesis inhibition by L-α-difluoromethylornithine (DFMO) : Cellular mechanisms for DFMO-mediated ototoxicity. / Nie, Liping; Feng, Weihong; Diaz, Rodney C; Gratton, Michael A.; Doyle, Karen Jo; Yamoah, Ebenezer N.
In: Journal of Biological Chemistry, Vol. 280, No. 15, 15.04.2005, p. 15097-15102.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Functional consequences of polyamine synthesis inhibition by L-α-difluoromethylornithine (DFMO)
T2 - Cellular mechanisms for DFMO-mediated ototoxicity
AU - Nie, Liping
AU - Feng, Weihong
AU - Diaz, Rodney C
AU - Gratton, Michael A.
AU - Doyle, Karen Jo
AU - Yamoah, Ebenezer N.
PY - 2005/4/15
Y1 - 2005/4/15
N2 - L-α-Difluoromethylornithine (DFMO) is a chemopreventive agent for colon cancer in clinical trials. Yet, the drug produces an across-frequency elevation of the hearing threshold, suggesting that DFMO may affect a common trait along the cochlear spiral. The mechanism for the ototoxic effects of DFMO remains uncertain. The cochlear duct is exclusively endowed with endocochlear potential (EP). EP is a requisite for normal sound transduction, as it provides the electromotive force that determines the magnitude of the receptor potential of hair cells. EP is generated by the high throughput of K+ across cells of the stria vascularis, conferred partly by the activity of Kir4.1 channels. Here, we show that the ototoxicity of DFMO may be mediated by alteration of the inward rectification of Kir4.1 channels, resulting in a marked reduction in EP. These findings are surprising given that the present model for EP generation asserts that Kir4.1 confers the outflow of K+ in the stria vascularis. We have proposed an alternative model. These findings should also enable the rational design of new pharmaceuticals devoid of the untoward effect of DFMO.
AB - L-α-Difluoromethylornithine (DFMO) is a chemopreventive agent for colon cancer in clinical trials. Yet, the drug produces an across-frequency elevation of the hearing threshold, suggesting that DFMO may affect a common trait along the cochlear spiral. The mechanism for the ototoxic effects of DFMO remains uncertain. The cochlear duct is exclusively endowed with endocochlear potential (EP). EP is a requisite for normal sound transduction, as it provides the electromotive force that determines the magnitude of the receptor potential of hair cells. EP is generated by the high throughput of K+ across cells of the stria vascularis, conferred partly by the activity of Kir4.1 channels. Here, we show that the ototoxicity of DFMO may be mediated by alteration of the inward rectification of Kir4.1 channels, resulting in a marked reduction in EP. These findings are surprising given that the present model for EP generation asserts that Kir4.1 confers the outflow of K+ in the stria vascularis. We have proposed an alternative model. These findings should also enable the rational design of new pharmaceuticals devoid of the untoward effect of DFMO.
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U2 - 10.1074/jbc.M409856200
DO - 10.1074/jbc.M409856200
M3 - Article
VL - 280
SP - 15097
EP - 15102
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 15
ER -