Down-regulation of mitochondrial F1F0-ATP synthase in human colon cancer cells with induced 5-fluorouracil resistance.

Abstract

5-Fluorouracil (5-FU) is widely used for treatment of advanced colorectal cancer. However, it is common for such patients to develop resistance to 5-FU, and this drug resistance becomes a critical problem for chemotherapy. The mechanisms underlying this resistance are largely unknown. To screen for proteins possibly responsible for 5-FU resistance, cells resistant to 5-FU were derived from human colon cancer cell lines and two-dimensional gel electrophoresis-based comparative proteomics was done. Two-dimensional gel electrophoresis data showed there was lower expression of the alpha subunit of mitochondrial F(1)F(0)-ATP synthase (ATP synthase) in 5-FU-resistant cells compared with parent cells. Western blotting showed that expression of other ATP synthase complex subunits was also lower in 5-FU-resistant cell lines and that these resistant cells also showed decreased ATP synthase activity and reduced intracellular ATP content. The ATP synthase inhibitor, oligomycin A, strongly antagonized 5-FU-induced suppression of cell proliferation. When 5-FU sensitivity was compared with ATP synthase activity in six different human colon cancer cell lines, a positive correlation has been found. Furthermore, suppressed ATP synthase d-subunit expression by siRNA transfection increased cell viability in the presence of 5-FU. Bioenergetic dysfunction of mitochondria has been reported as a hallmark of many types of cancers (i.e., down-regulation of ATP synthase beta-subunit expression in liver, kidney, colon, squamous oesophageal, and lung carcinomas, as well as in breast and gastric adenocarcinomas). Our findings show that ATP synthase down-regulation may not only be a bioenergetic signature of colorectal carcinomas but may also lead to cellular events responsible for 5-FU resistance.

• Authors: Young-Kyoung Shin, Byong Chul Yoo, Hee Jin Chang, Eunkyung Jeon, Sung-Hye Hong, Mi-Sun Jung, Soo-Jeong Lim, Jae-Gahb Park
• Journal: Cancer research (Cancer Res) Vol. 65 Issue 8 Pg. 3162-70 (Apr 15 2005) ISSN: 0008-5472 [Print] United States
• PMID: 15833846 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antimetabolites, Antineoplastic
• Aurovertins
• Enzyme Inhibitors
• Oligomycins
• RNA, Small Interfering
• oligomycin A
• aurovertin B
• F1F0-ATP synthase
• Mitochondrial Proton-Translocating ATPases
• Fluorouracil

Topics

• Antimetabolites, Antineoplastic (pharmacology)
• Aurovertins (pharmacology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Colonic Neoplasms (drug therapy, enzymology, genetics)
• Down-Regulation
• Drug Resistance, Neoplasm
• Energy Metabolism
• Enzyme Inhibitors (pharmacology)
• Fluorouracil (pharmacology)
• Humans
• Mitochondria (enzymology)
• Mitochondrial Proton-Translocating ATPases (antagonists & inhibitors, biosynthesis, genetics)
• Oligomycins (pharmacology)
• RNA, Small Interfering (genetics)
• Transfection