Inhibition of hepatic tumor cell proliferation in vitro and tumor growth in vivo by taltobulin, a synthetic analogue of the tripeptide hemiasterlin

Figure 1 Inhibitory effect of HTI-286 on proliferation of MH, HepG2, and Hep3B cells. Inhibitory effect upon HTI-286 treatment was highly significant in all three hepatic carcinoma cell lines. MH (A), HepG2 (B) and Hep3B (C) cells were exposed to 1, 3, and 3 nmol/L of HTI-286, respectively, for two cell doubling times. Student’s t test analysis showed two-sided P values of 0.005, 0.002 and 0.001 for MH, HepG2, and Hep3B, respectively.

Figure 2 Effect of HTI-286 on primary human hepatocytes. Human hepatocytes were exposed to HTI-286 for 24 and 48 h at concentrations between 1 nmol/L and 1 mmol/L. No significant decrease in viable cells was detected in MTT assay at any concentration.

Figure 3 BrdU incorporation in MH cells treated with 1 nmol/L HTI-286. Decrease in S phase was observed as BrdU incorporation decreased significantly (P = 0.024) in MH cells compared to the untreated cells when exposed to 1 nmol/L HTI-286 for two cell doubling times.

Figure 4 Microtubule (MT) structure assessed by immunofluorescene microscopy with a specific α-tubulin antibody. A and B: Untreated Hep3B and HepG2 cells showed dense and complex MT network in the cytoplasm. Insets A and B represent cells after HTI-286 treatment at 3 nmol/L for two cell doubling times. Decreased cytoplasmic microtubule density and diffuse staining were observed. Magnification x 40 except for insets, which are magnified further to outline the morphological changes. C: MH cells treated with HTI-286 at 1 nmol/L for two cell doubling times showed multipolar spindles, indicating disruption of the microtubule network in mitotic cells.

Figure 5 In vivo inhibition of tumor growth under HTI-286 treatment. HTI-286 was injected on d 1, 5, 9 and 15. By d 7, tumor growth significantly differed between the control and HTI-286 group (^aP = 0.042; ^bP = 0.0001). Two weeks after the last HTI-286 injection, the inhibitory effect was diminished between both groups (P = 0.056).