ritonavir and Urinary-Bladder-Neoplasms

Simultaneous inhibition of histone deacetylase and proteasomes induces endoplasmic reticulum (ER) stress efficiently. RTS-V5 is the first dual histone deacetylase-proteasome inhibitor, and we anticipated that combining it with the cytochrome P450 family 3 subfamily A member 4 inhibitor ritonavir would enhance its activity in bladder cancer cells.. Using bladder cancer cells (human T-24, J-82, murine MBT-2), we evaluated the ability and mechanism by which the combination of RTS-V5 and ritonavir induced ER stress and killed cancer cells.. The combination of RTS-V5 and ritonavir triggered robust apoptosis and inhibited bladder cancer growth effectively in vitro and in vivo. It caused ubiquitinated protein accumulation and induced ER stress synergistically. The combination inhibited the mammalian target of rapamycin pathway by increasing the expression of AMP-activated protein kinase. We also found that the combination caused histone and tubulin hyperacetylation.. Ritonavir enhances the ability of RTS-V5 to cause ER stress in bladder cancer cells.

Topics: Acetylation; Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Drug Synergism; Endoplasmic Reticulum Stress; Histone Deacetylase Inhibitors; Histones; Humans; Mice; Proteasome Inhibitors; Ritonavir; Signal Transduction; TOR Serine-Threonine Kinases; Urinary Bladder Neoplasms; Xenograft Model Antitumor Assays

The human immunodeficiency virus (HIV) protease inhibitor nelfinavir acts against malignancies by inducing endoplasmic reticulum (ER) stress. The HIV protease inhibitor ritonavir, on the other hand, not only induces ER stress but also inhibits P-glycoprotein's pump activity and thereby enhances the effects of its substrate drugs. We therefore postulated that ritonavir in combination with nelfinavir would kill bladder cancer cells effectively by inducing ER stress cooperatively and also enhancing nelfinavir's effect. Nelfinavir was shown to be a P-glycoprotein substrate, and the combination of nelfinavir and ritonavir inhibited bladder cancer cell growth synergistically. It also suppressed colony formation significantly. The combination significantly increased the number of cells in the sub-G1 fraction and also the number of annexin V+ cells, confirming robust apoptosis induction. The combination induced ER stress synergistically, as evidenced by the increased expression of glucose-regulated protein 78, ER-resident protein 44, and endoplasmic oxidoreductin-1-like protein. It also increased the expression of the mammalian target of rapamycin (mTOR) inhibitor AMP-activated protein kinase and caused dephosphorylation of S6 ribosomal protein, demonstrating that the combination also inhibited the mTOR pathway. We also found that the combination enhanced histone acetylation synergistically by decreasing the expression of HDACs 1, 3, and 6.

Topics: Acetylation; Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Synergism; Endoplasmic Reticulum Stress; Histones; Humans; Nelfinavir; Ritonavir; Urinary Bladder Neoplasms

There is no curative treatment for advanced bladder cancer. Causing ubiquitinated protein accumulation and endoplasmic reticulum stress is a novel approach to cancer treatment. The HIV protease inhibitor ritonavir has been reported to suppress heat shock protein 90 and increase the amount of unfolded proteins in the cell. If the proteasome functions normally, however, they are rapidly degraded. We postulated that the novel proteasome inhibitor ixazomib combined with ritonavir would kill bladder cancer cells effectively by inhibiting degradation of these unfolded proteins and thereby causing ubiquitinated proteins to accumulate. The combination of ritonavir and ixazomib induced drastic apoptosis and inhibited the growth of bladder cancer cells synergistically. The combination decreased the expression of cyclin D1 and cyclin-dependent kinase 4, and increased the sub-G

Topics: Acetylation; Antineoplastic Agents; Apoptosis; Boron Compounds; Cell Line, Tumor; Cyclin D1; Cyclin-Dependent Kinase 4; Drug Synergism; Endoplasmic Reticulum Stress; Glycine; Humans; Proteasome Inhibitors; Ritonavir; Ubiquitinated Proteins; Ubiquitination; Urinary Bladder Neoplasms