Betulinic acid sensitization of low pH adapted human melanoma cells to hyperthermia

P. R. Wachsberger, Randy M Burd, M. L. Wahl, D. B. Leeper

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Betulinic acid is a known inducer of apoptosis in human melanoma that is most effective under conditions of low pH. It was hypothesized that betulinic acid, in combination with acute acidification and/or hyperthermia, would induce higher levels of apoptosis and cytotoxicity in low pH-adapted human melanoma cells than in cells grown at pH 7.3. DB-1 human melanoma cells, adapted to a tumour-like growth pH of 6.7, were exposed to hyperthermia (2 h at 42°C) and/or betulinic acid (4-10 μg/ml) and compared with cells grown at a physiological pH of 7.3 or after acute acidification from pH 7.3-6.3 or pH 6.7-6.3. Betulinic acid induced higher levels of apoptosis and cytotoxicity in low pH-adapted cells than in cells grown at pH 7.3, as measured by the terminal deoxynucleotidyl transferase (TdT) DNA fragmentation assay (TUNEL), the MTS cell viability assay, and single cell survival. Acute acidification of low pH adapted cells rendered them more susceptible to betulinic acid-induced apoptosis and cytotoxicity. In the presence of hyperthermia at 42°C for 2h, cells grown at pH 7.3 were not sensitized to heat killing by betulinic acid, whereas cells grown at pH 7.3 and acutely acidified to pH 6.3, cells adapted to growth at pH 6.7 and cells adapted to growth at pH 6.7 and acutely acidified to pH 6.3 were all similarly sensitized to heat killing by betulinic acid, with survival values of 5, 9 and 2%, respectively. It is concluded that betulinic acid may be useful in potentiating the therapeutic efficacy of hyperthermia as a cytotoxic agent in acidotic areas of tumours with minimal effect in normal tissues growing at pH 7.3.

Original languageEnglish (US)
Pages (from-to)153-164
Number of pages12
JournalInternational Journal of Hyperthermia
Volume18
Issue number2
DOIs
StatePublished - 2002
Externally publishedYes

Fingerprint

Melanoma
Fever
Apoptosis
betulinic acid
Cell Survival
Growth
Hot Temperature
Induced Hyperthermia
DNA Nucleotidylexotransferase
Cytotoxins
In Situ Nick-End Labeling
DNA Fragmentation
Neoplasms

Keywords

  • Apoptosis
  • Betulinic acid
  • Hyperthermia
  • Low pH

ASJC Scopus subject areas

  • Cancer Research
  • Radiological and Ultrasound Technology

Cite this

Betulinic acid sensitization of low pH adapted human melanoma cells to hyperthermia. / Wachsberger, P. R.; Burd, Randy M; Wahl, M. L.; Leeper, D. B.

In: International Journal of Hyperthermia, Vol. 18, No. 2, 2002, p. 153-164.

Research output: Contribution to journalArticle

Wachsberger, P. R. ; Burd, Randy M ; Wahl, M. L. ; Leeper, D. B. / Betulinic acid sensitization of low pH adapted human melanoma cells to hyperthermia. In: International Journal of Hyperthermia. 2002 ; Vol. 18, No. 2. pp. 153-164.
@article{6a15e560aa01467bbee8919da51c1a74,
title = "Betulinic acid sensitization of low pH adapted human melanoma cells to hyperthermia",
abstract = "Betulinic acid is a known inducer of apoptosis in human melanoma that is most effective under conditions of low pH. It was hypothesized that betulinic acid, in combination with acute acidification and/or hyperthermia, would induce higher levels of apoptosis and cytotoxicity in low pH-adapted human melanoma cells than in cells grown at pH 7.3. DB-1 human melanoma cells, adapted to a tumour-like growth pH of 6.7, were exposed to hyperthermia (2 h at 42°C) and/or betulinic acid (4-10 μg/ml) and compared with cells grown at a physiological pH of 7.3 or after acute acidification from pH 7.3-6.3 or pH 6.7-6.3. Betulinic acid induced higher levels of apoptosis and cytotoxicity in low pH-adapted cells than in cells grown at pH 7.3, as measured by the terminal deoxynucleotidyl transferase (TdT) DNA fragmentation assay (TUNEL), the MTS cell viability assay, and single cell survival. Acute acidification of low pH adapted cells rendered them more susceptible to betulinic acid-induced apoptosis and cytotoxicity. In the presence of hyperthermia at 42°C for 2h, cells grown at pH 7.3 were not sensitized to heat killing by betulinic acid, whereas cells grown at pH 7.3 and acutely acidified to pH 6.3, cells adapted to growth at pH 6.7 and cells adapted to growth at pH 6.7 and acutely acidified to pH 6.3 were all similarly sensitized to heat killing by betulinic acid, with survival values of 5, 9 and 2{\%}, respectively. It is concluded that betulinic acid may be useful in potentiating the therapeutic efficacy of hyperthermia as a cytotoxic agent in acidotic areas of tumours with minimal effect in normal tissues growing at pH 7.3.",
keywords = "Apoptosis, Betulinic acid, Hyperthermia, Low pH",
author = "Wachsberger, {P. R.} and Burd, {Randy M} and Wahl, {M. L.} and Leeper, {D. B.}",
year = "2002",
doi = "10.1080/02656730110091333",
language = "English (US)",
volume = "18",
pages = "153--164",
journal = "International Journal of Hyperthermia",
issn = "0265-6736",
publisher = "Informa Healthcare",
number = "2",

}

TY - JOUR

T1 - Betulinic acid sensitization of low pH adapted human melanoma cells to hyperthermia

AU - Wachsberger, P. R.

AU - Burd, Randy M

AU - Wahl, M. L.

AU - Leeper, D. B.

PY - 2002

Y1 - 2002

N2 - Betulinic acid is a known inducer of apoptosis in human melanoma that is most effective under conditions of low pH. It was hypothesized that betulinic acid, in combination with acute acidification and/or hyperthermia, would induce higher levels of apoptosis and cytotoxicity in low pH-adapted human melanoma cells than in cells grown at pH 7.3. DB-1 human melanoma cells, adapted to a tumour-like growth pH of 6.7, were exposed to hyperthermia (2 h at 42°C) and/or betulinic acid (4-10 μg/ml) and compared with cells grown at a physiological pH of 7.3 or after acute acidification from pH 7.3-6.3 or pH 6.7-6.3. Betulinic acid induced higher levels of apoptosis and cytotoxicity in low pH-adapted cells than in cells grown at pH 7.3, as measured by the terminal deoxynucleotidyl transferase (TdT) DNA fragmentation assay (TUNEL), the MTS cell viability assay, and single cell survival. Acute acidification of low pH adapted cells rendered them more susceptible to betulinic acid-induced apoptosis and cytotoxicity. In the presence of hyperthermia at 42°C for 2h, cells grown at pH 7.3 were not sensitized to heat killing by betulinic acid, whereas cells grown at pH 7.3 and acutely acidified to pH 6.3, cells adapted to growth at pH 6.7 and cells adapted to growth at pH 6.7 and acutely acidified to pH 6.3 were all similarly sensitized to heat killing by betulinic acid, with survival values of 5, 9 and 2%, respectively. It is concluded that betulinic acid may be useful in potentiating the therapeutic efficacy of hyperthermia as a cytotoxic agent in acidotic areas of tumours with minimal effect in normal tissues growing at pH 7.3.

AB - Betulinic acid is a known inducer of apoptosis in human melanoma that is most effective under conditions of low pH. It was hypothesized that betulinic acid, in combination with acute acidification and/or hyperthermia, would induce higher levels of apoptosis and cytotoxicity in low pH-adapted human melanoma cells than in cells grown at pH 7.3. DB-1 human melanoma cells, adapted to a tumour-like growth pH of 6.7, were exposed to hyperthermia (2 h at 42°C) and/or betulinic acid (4-10 μg/ml) and compared with cells grown at a physiological pH of 7.3 or after acute acidification from pH 7.3-6.3 or pH 6.7-6.3. Betulinic acid induced higher levels of apoptosis and cytotoxicity in low pH-adapted cells than in cells grown at pH 7.3, as measured by the terminal deoxynucleotidyl transferase (TdT) DNA fragmentation assay (TUNEL), the MTS cell viability assay, and single cell survival. Acute acidification of low pH adapted cells rendered them more susceptible to betulinic acid-induced apoptosis and cytotoxicity. In the presence of hyperthermia at 42°C for 2h, cells grown at pH 7.3 were not sensitized to heat killing by betulinic acid, whereas cells grown at pH 7.3 and acutely acidified to pH 6.3, cells adapted to growth at pH 6.7 and cells adapted to growth at pH 6.7 and acutely acidified to pH 6.3 were all similarly sensitized to heat killing by betulinic acid, with survival values of 5, 9 and 2%, respectively. It is concluded that betulinic acid may be useful in potentiating the therapeutic efficacy of hyperthermia as a cytotoxic agent in acidotic areas of tumours with minimal effect in normal tissues growing at pH 7.3.

KW - Apoptosis

KW - Betulinic acid

KW - Hyperthermia

KW - Low pH

UR - http://www.scopus.com/inward/record.url?scp=0036126037&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036126037&partnerID=8YFLogxK

U2 - 10.1080/02656730110091333

DO - 10.1080/02656730110091333

M3 - Article

C2 - 11911485

AN - SCOPUS:0036126037

VL - 18

SP - 153

EP - 164

JO - International Journal of Hyperthermia

JF - International Journal of Hyperthermia

SN - 0265-6736

IS - 2

ER -