Suppression of colorectal cancer growth using an adenovirus vector expressing an antisense K-ras RNA.
In human colorectal cancer, K-ras point mutations occur in approximately 40-50% of the cases, a frequency second only to pancreatic cancer (80-90%). Unlike pancreatic and lung cancers, however, the tumor-suppressive effect of antisense K-ras RNA expression has not been examined for colorectal cancers. A recombinant adenovirus vector expressing an antisense or sense K-ras gene fragment (AxCA-AS-K-ras or AxCA-S-K-ras) was first transduced into seven human colorectal cancer cell lines. Stable expression of antisense or sense K-ras RNA was detected by RNA blot analysis. Western blot analysis confirmed a reduction of up to 25% of K-ras-specific p21 protein in the antisense K-ras-transduced HCT-15 cells. In contrast to our previous findings on pancreatic cancer, the status of K-ras point mutations was not correlated with the growth-suppressive effect of the antisense K-ras vector: both the K-ras-mutation-positive and -negative colorectal cancer cell lines were suppressed for their growth in vitro. There was no growth-inhibitory effect on normal cells such as hepatocytes. Next, to test the efficacy in vivo, HCT-15 cells were inoculated subcutaneously into the left flank of SCID mice, and AxCA-AS-K-ras was injected intratumorally three times after the tumor mass was established. The infection of AxCA-AS-K-ras, but not the control AxCA-S-K-ras, significantly suppressed the growth of the HCT-15 subcutaneous tumor. This study shows that the adenovirus-mediated in vivo gene transfer of the antisense K-ras construct may be a useful therapeutic strategy for colorectal cancer.
Nakano
M
M
Genetics Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan.
Aoki
K
K
Matsumoto
N
N
Ohnami
S
S
Hatanaka
K
K
Hibi
T
T
Terada
M
M
Yoshida
T
T
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D015179:Colorectal Neoplasms / Q000628:therapy*; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D011905:Genes, ras / Q000235:genetics*; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D008957:Models, Genetic; D016376:Oligonucleotides, Antisense / Q000096:biosynthesis / Q000235:genetics*; D017354:Point Mutation; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis; D012313:RNA / Q000235:genetics*; D013997:Time Factors; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D016376:Oligonucleotides, Antisense; D012313:RNA; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)