Hydroxylated benzo[c]phenanthrene metabolites cause osteoblast apoptosis and skeletal abnormalities in fish

Nobuo Suzuki, Masato Honda, Masayuki Sato, Shuhei Yoshitake, Kimi Kawabe, Yoshiaki Tabuchi, Toshiki Omote, Toshio Sekiguchi, Yukihiro Furusawa, Akira Toriba, Ning Tang, Yohei Shimasaki, Edward G. Nagato, Lulu Zhang, Ajai K. Srivastav, Thumronk Amornsakun, Yoichiro Kitani, Hajime Matsubara, Takashi Yazawa, Jun HirayamaAtsuhiko Hattori, Yuji Oshima, Kazuichi Hayakawa

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

To study the toxicity of 3-hydroxybenzo[c]phenanthrene (3-OHBcP), a metabolite of benzo[c]phenanthrene (BcP), first we compared it with its parent compound, BcP, using an in ovo-nanoinjection method in Japanese medaka. Second, we examined the influence of 3-OHBcP on bone metabolism using goldfish. Third, the detailed mechanism of 3-OHBcP on bone metabolism was investigated using zebrafish and goldfish. The LC50s of BcP and 3-OHBcP in Japanese medaka were 5.7 nM and 0.003 nM, respectively, indicating that the metabolite was more than 1900 times as toxic as the parent compound. In addition, nanoinjected 3-OHBcP (0.001 nM) induced skeletal abnormalities. Therefore, fish scales with both osteoblasts and osteoclasts on the calcified bone matrix were examined to investigate the mechanisms of 3-OHBcP toxicity on bone metabolism. We found that scale regeneration in the BcP-injected goldfish was significantly inhibited as compared with that in control goldfish. Furthermore, 3-OHBcP was detected in the bile of BcP-injected goldfish, indicating that 3-OHBcP metabolized from BcP inhibited scale regeneration. Subsequently, the toxicity of BcP and 3-OHBcP to osteoblasts was examined using an in vitro assay with regenerating scales. The osteoblastic activity in the 3-OHBcP (10-10 to 10-7 M)-treated scales was significantly suppressed, while BcP (10-11 to 10-7 M)-treated scales did not affect osteoblastic activity. Osteoclastic activity was unchanged by either BcP or 3-OHBcP treatment at each concentration (10-11 to 10-7 M). The detailed toxicity of 3-OHBcP (10-9 M) in osteoblasts was then examined using gene expression analysis on a global scale with fish scales. Eight genes, including APAF1, CHEK2, and FOS, which are associated with apoptosis, were identified from the upregulated genes. This indicated that 3-OHBcP treatment induced apoptosis in fish scales. In situ detection of cell death by TUNEL methods was supported by gene expression analysis. This study is the first to demonstrate that 3-OHBcP, a metabolite of BcP, has greater toxicity than the parent compound, BcP.

Original languageEnglish
Article number113401
JournalEcotoxicology and Environmental Safety
Volume234
DOIs
Publication statusPublished - Apr 1 2022

All Science Journal Classification (ASJC) codes

  • Pollution
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis

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