Authors: Arora V, Knapp DC, Smith BL, Statdfield ML, Stein DA, Reddy MT, Weller DD, Iversen PL

Title: c-Myc antisense limits rat liver regeneration and indicates role for c-Myc in regulating cytochrome P-450 3A activity

Citation: Exp Ther 2000 Mar 292(3):921-8

Abstract: Expression of c-myc protein is associated with cell proliferation. The present study uses antisense oligomers to inhibit c-myc expression in the regenerating rat liver after 70% partial hepatectomy (PH). Antisense phosphorodiamidate morpholino oligomers (novel DNA analogs) were administered i.p. immediately after surgery to block expression of c-myc within the first 24 h after PH. A 20-mer PMO complimentary to the c-myc mRNA at the translation start site was an effective sequence (AVI-4126, 5'-ACGTTGAGGGGCATCGTCGC-3'). A single i.p. dose of 0.5 mg/kg AVI-4126 caused reduction of the regenerating liver c-myc protein in a sequence-specific and dose-dependent manner. Inhibition of c-myc expression resulted in reduction of proliferating cell nuclear antigen and arrested cells in the G(0)/G(1) phase of the cell cycle. The ratio of G(2):G(0) cell populations in the regenerating liver 24 h after PH dropped from 29.1 in saline vehicle-treated rats to 18.0 in rats treated with 2.5 mg/kg AVI-4126. The expression of cell cycle checkpoint protein p53 was inhibited with increasing doses of AVI-4126, but expression of p21(waf-1) was unaffected. The activity of cytochrome P-450 3A2 (CYP3A2) was evaluated by immunoblot analysis and erythromycin N-demethylation. AVI-4126 did not alter CYP3A activity in nonhepatectamized animals but showed a dose-dependent decrease in PH rats. We conclude that AVI-4126, antisense oligomer to c-myc, can reduce cell proliferation in the regenerating rat liver. Furthermore, inhibition of c-myc may indirectly influence the expression of CYP3A.

Organism: rats, Sprague Dawley

Delivery Method: Injection

First Oligo Name: AVI-4126

First Oligo Sequence: ACGTTGAGGGGCATCGTCGC

First GenBank Number: Y00396

First Oligo Type: splice-site

Second Oligo Name: 1-22-21

Second Oligo Sequence: GGGAGGUUGUCUGUCAGUGCUGCUACGGGG

Second GenBank Number:

Second Oligo Type: splice-site

Third Oligo Name: 1-22-111

Third Oligo Sequence: GGAGGTTGTCTGTCAGTGCTGC

Third GenBank Number:

Third Oligo Type: splice-site

Fourth Oligo Name: 1-22-115

Fourth Oligo Sequence: GCTACGGGGAGTTGCAATC

Fourth GenBank Number:

Fourth Oligo Type: splice-site

Fifth Oligo Name: avi-4126 scramb

Fifth Oligo Sequence: ACTGTGAGGGCGATCGCTGC

Fifth GenBank Number:

Fifth Oligo Type: negative control

Sixth Oligo Name: 1-0-367

Sixth Oligo Sequence: GCCCCTCGTTTTACTTCCCTCTCG

Sixth GenBank Number:

Sixth Oligo Type: negative control

Seventh Oligo Name: 1-0-368

Seventh Oligo Sequence: TACCTCTCCGAGGTCCCCGACG

Seventh GenBank Number:

Seventh Oligo Type: negative control

Eighth Oligo Name:

Eighth Oligo Sequence:

Eighth GenBank Number:

Eighth Oligo Type: