| Budget Amount *help |
¥8,700,000 (Direct Cost: ¥8,700,000)
Fiscal Year 1995: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1994: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1993: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Research Abstract |
Uterine cervical cancer is the most common genital malignancy, and a strong association with human papillomaviruses (HPV) has been suggested. Only part of the HPV genome, encoding the E6 and E7 proteins, is consistently retained and expressed in Cancer cells. One important function of the E6 protein is its ability to form a complex with the cellular p53 protein, resulting in an ubiguitin-dependent degradation of the letter. Likewise, the E7 oncoprotein also forms a complex with the cell-encoded Rb protein. In the present study, first of all, we tried to confirm the association of cervical cancer with HPV infection. HPV DNA sequences were present in 43 out of 47 primary cervical cancers (91.5%). One of these cancers contained a p53 gene mutation. In addition, One of the remaining four HPV-negative cancers also contained a p53 mutation. As a result, p53 inactivation either by E6 or p53 gene mutations corresponded to the development of 44 primary cervical cancers (93.6%). We obtained both
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primary and recurrent tumors from 4 cases. In two of these cases, the HPV genomes that were present in an episomal state in the primary tumors were observed to have disappeared in the recurrent tumors. One of these recurrent tumors also contained a p53 gene mutation, which suggested the possibility that p53 inactivation was required in order to maintain the aggressive behavior this cancer either by an HPV infection or by a p53 gene umtation.
Antisense oligodeoynucleotides (oligomers) have a critical role for dregs targeted specifically against oncogene. The importance of HPV E6 and E7 has been identified to include the cervical cancer and maintain its phenotype. Thus, we tried to obtain evidence for the inhibitory effects of antisense oligomers to the E6/E7 region of HPV16 on transformed cervical epithelial cell lines. The oligomers greatly reduced both cell numbers and H^3-Thymidine uptake in PHK16 and C4II cells. This potent antiproliferative activity accompanied the suppression of target gene expression. In contrast, the effects on SiHa cells were less remarkable. These inhibitory effects were not accompanied any noticeable inhibition of E7 protein synthesis. Thus, we design more efficient antisense molecules by binding the psolaren that is a strong DNA adduct, to the oligomors. The psolaren-conjugated oligomers showed the strong inhibitory effects on SiHa cells. The psolaren conjugation was able to lessen the concentration into 1/40, that showed the similar degree of growth inhibition, compared to the 20muM phospborothioate oligomers. However, the psolaren conjugated oligomers did not show any inhibitory effect on growth of the normal human epidermal karatinocytes. Less
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