Intraluminal Epidermal Growth Factor Affects Growth of N‐Methyl‐N‐nitrosourea‐initiated Rat Bladder Carcinoma

Koji Kawai, Hitoshi Kawamata, Shuji Kameyama, Alfred Rademaker, Ryoichi Oyasu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


To confirm our recent finding that epidermal growth factor (EGF) appeared to contribute to the tumor‐enhancing effect demonstrated by normal rat urine, we conducted 2 experiments using our heterotopically transplanted rat urinary bladder model. In experiment 1, after a single dose (0.25 mg) of N‐methyl‐N‐nitrosourea (MNU), we intravesically administered EGF (0.5 ml of 500 ng/ml phosphate‐buffered saline) once a week for 30 weeks. Instillation of EGF induced a significantly larger number of tumors than did instillation of the vehicle (P=0.03). EGF without MNU initiation did not induce tumors. In experiment 2, 2 groups received instillation of killed Escherichia coli (5 × 108 cells)/0.5 ml phosphate‐buffered saline once a week for 4 weeks to expand the MNU‐initiated cell population. Subsequent EGF treatment significantly increased the incidence of tumors (P=0.01). In the groups which did not receive killed E. coli, EGF treatment induced a significantly higher number of tumors than did vehicle treatment (P<0.001). All of the tumors were low‐grade, superficial transitional cell carcinomas. These observations indicate that EGF acts as a growth‐stimulating factor on dormant neoplastic cells and thereby increases the number of tumors.

Original languageEnglish (US)
Pages (from-to)429-434
Number of pages6
JournalJapanese Journal of Cancer Research
Issue number5
StatePublished - May 1995


  • Bladder tumor
  • Epidermal growth factor
  • Growth stimulation
  • N‐Methyl‐N‐nitrosourea

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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