Open AccessDevelopment and Distribution of 2‐Amino‐1‐methyl‐6‐phenylimidazo[4,5‐ b ]‐pyridine (PhIP)‐induced Aberrant Crypt Foci in the Rat Large Intestine
Author(s) -
Tsukamoto Tetsuya,
Kozaki Kenichi,
Nishikawa Yoko,
Yamamoto Masami,
Fukami Hiroko,
Inoue Manami,
Wakabayashi Keiji,
Tatematsu Masae
Publication year - 1999
Publication title -
japanese journal of cancer research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 0910-5050
DOI - 10.1111/j.1349-7006.1999.tb00806.x
Subject(s) - crypt , aberrant crypt foci , cecum , large intestine , pathology , biology , epithelium , colorectal cancer , chemistry , cancer , medicine , endocrinology , biochemistry , colonic disease , ecology , genetics
Aberrant crypt foci (ACF) are generally considered to be preneoplastic lesions for colon cancer. To assess their induction by 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐ b ]pyridine (PhIP), a colon carcinogen, we performed a sequential study of ACF morphology and localization. F344 male rats were given PhIP, and methylene blue‐stained colon epithelium and isolated crypts were analyzed at weeks 12, 25, 50, and 75. Each crypt was classified into 2 groups, “single” with round bottoms and “bifurcating” displaying V‐shaped clefts (indicating proliferation). In combination with the number of crypts in an ACF, this classification was a good indicator for the generation of ACF in line with the fission mechanism of growth. Increasing numbers of crypts in ACF through weeks 12 to 75 and decreased percentages of ACF with bifurcating crypts at the late time points indicated that proliferation of crypts occurs predominantly during the early stages. The distribution pattern showed a significant shift ( P < 0.5) from the distal to the proximal part of the large intestine between weeks 25 and 50. Adenocarcinomas were first found to develop at week 50 in the ascending colon and cecum where bifurcating crypts were generally lacking at weeks 12 and 25. These data suggest the existence of (1) proliferating ACF which contains bifurcating crypt(s) and (2) quiescent or senescent ACF which consists of only single crypts.