Parotin subunit and its synthetic peptide possess interleukin 1-like activity and exert stimulating effects on liver...

We have investigated whether parotin subunit (PS) and its partial synthetic peptide (P-10.2: TDDTAIVLLK), possess interleukin 1 (IL-1)-like activities, and act on cell lines other than lymphocytes. When Chang liver cells were cultured with P-10.2, PS or IL-1, P-10.2 and PS augmented the growth of Chang liver cells. On the other hand, IL-1 enhanced the growth of Change liver cells at 1 day of the initial culture and subsequently failed to enhance during at least 4-day incubation. Next, effects of P-10.2 and PS on the growth of Alexander cells and MH134 were investigated. The proliferation of Alexander cells was inhibited with P-10.2 or PS but not with IL-1. P-10.2 inhibited the growth of MH134 at day 1 and 3, while the growth of MH134 was shown not to be inhibited with PS and IL-1 at day 1, but rather suppressed them at day 3. These results suggest that P-10.2 augments the growth of non-malignant liver cells (Chang liver cells) but inhibits that of hepatoma cells (Alexander cells and MH134). P-10.2 enhanced fibrinogen and hepatoglobin secretion from Chang liver cells. In addition to their liver cell activation, P-10.2 and PS stimulated ACTH and beta-endorphin secretion from AtT-20 cells.