Systemic transduction of p16INK4A antitumor peptide inhibits the growth of MBT-2 mouse bladder tumor cell line grafts

Abstract

p16(INK4a) (p16), a key molecule in bladder tumor development, inhibits the activities of cyclin-dependent kinases (CDKs) and maintains the retinoblastoma protein (pRb) in its active hypophosphorylated state. Following the finding that the p16 antitumor peptide dramatically inhibits the growth of aggressive leukemia/lymphoma through the restoration of p16 function using the Wr-T peptide transporter system, in this study, we developed a systemic therapy using mouse‑p16 peptide (m‑p16) in subcutaneous p16‑null mouse bladder tumors. In vitro analysis showed that the growth of p16‑null bladder tumor cells and the hyperphosphorylation of their pRbs were inhibited by p16 transduction in a concentration‑dependent manner. In an animal model, p16‑null MBT‑2 cells were injected subcutaneously into KSN/SKC nude mice. The systemic delivery of the m‑p16 peptide using Wr‑T by cardiac injection significantly inhibited the growth of solid MBT‑2 tumors compared with the control phosphate‑buffered saline (PBS) injection. Histological examination by TUNEL staining revealed that apoptosis was increased and pRb phosphorylation was inhibited. Thus, the systemic peptide delivery of p16 restores the hypophosphorylation of pRb and may be a useful tool for the treatment of bladder tumors.

Systemic transduction of p16INK4a antitumor peptide inhibits lung metastasis of the MBT‑2 bladder tumor cell line in mice

“…In urological cancer types, growth of renal cell carcinoma cell line graft was also inhibited by transduction of p16 peptide in mice (5). We previously reported the antitumor effect of a minimal inhibitory sequence peptide of p16 (p16-MIS) on allografts of solid tumor types, particularly urological cancer, derived from p16-deficient BT cell lines using a Wr-T system (6). In the present study, the suppression of BT metastasis with a p16-Wr-T peptide transfer system using a metastasis model of BT in mice was demonstrated, continuing on from our previous study.…”

“…The mouse BT cell line MBT-2 (Japanese Collection of Research Bioresources Cell Bank, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan) was cultured in RPMI-1640 containing 10% inactivated fetal bovine serum (Immuno-Biological Laboratories, Co., Ltd., Fujioka, Japan) at 37˚C in a humidified atmosphere containing 5% CO 2 . The MBT-2 cell line is a p16-deficient cell line with phosphorylation of the Rb protein (6). We previously confirmed the lack of expression of p16 in MBT-2 and that restoration of p16 function by peptide transduction resulted in downregulation of phosphorylated Rb expression (6).…”

“…The MBT-2 cell line is a p16-deficient cell line with phosphorylation of the Rb protein (6). We previously confirmed the lack of expression of p16 in MBT-2 and that restoration of p16 function by peptide transduction resulted in downregulation of phosphorylated Rb expression (6).…”

Up-regulation of p16 by miR-877-3p inhibits proliferation of bladder cancer

“…The frequent inactivation of p16 has been shown to be associated with the progression of bladder cancer to a more malignant phenotype [30–32]. Meanwhile, transduction of p16 antitumor peptide displayed inhibition of bladder cancer in mouse model, which indicated the restoration of p16 to be a probable treatment of bladder cancer [33]. Our data suggested that the increased expression of p16 induced by miR-877-3p could inhibit the growth of bladder cancer in vivo and in vitro through G1 phase arrest.…”

Research progress on bladder cancer molecular genetics

“…Further study revealed antitumor growth effect of systemic transduction of p16INK4A antitumor peptide in bladder tumor cell grafted mouse, indicating a potential treatment for bladder cancer. [86] Tuberous sclerosis complex 1 In bladder cancer, 9q34 deletion domain is consistent with tuberous sclerosis complex (TSC1) gene locus. Mutation analysis showed that it might be a target gene in 9q34.…”