Liposome-Encapsulated Bacillus Calmette-Guérin Cell Wall Skeleton Enhances Antitumor Efficiency for Bladder Cancer In Vitro and In Vivo via Induction of AMP-Activated Protein Kinase.

The Mycobacterium Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS), the main immune active center of BCG, is a potent candidate non-infectious immunotherapeutic drug and an alternative to live BCG for use against urothelial carcinoma. However, its application in anticancer therapy is limited, as BCG-CWS tends to aggregate in both aqueous and non-aqueous solvents. To improve the internalization of BCG-CWS into bladder cancer cells without aggregation, BCG-CWS was nanoparticulated at a 180 nm size in methylene chloride and subsequently encapsulated with conventional liposomes (CWS-Nano-CL) using an emulsified lipid (LEEL) method. In vitro cell proliferation assays showed that CWS-Nano-CL was more effective at suppressing bladder cancer cell growth compared to nonenveloped BCG-CWS. In an orthotopic implantation model of luciferase-tagged MBT2 bladder cancer cells, encapsulated BCG-CWS nanoparticles could enhance the delivery of BCG-CWS into the bladder and suppress tumor growth. Treatment with CWS-Nano-CL induced the inhibition of the mammalian target of rapamycin (mTOR) pathway and the activation of AMP-activated protein kinase (AMPK) phosphorylation, leading to apoptosis, both in vitro and in vivo. Furthermore, the antitumor activity of CWS-Nano-CL was mediated predominantly by reactive oxygen species (ROS) generation and AMPK activation, which induced endoplasmic reticulum (ER) stress, followed by c-Jun N-terminal kinase (JNK) signaling-mediated apoptosis. Therefore, our data suggest that the intravesical instillation of liposome-encapsulated BCG-CWS nanoparticles can facilitate BCG-CW cellular endocytosis and provide a promising drug-delivery system as a therapeutic strategy for BCG-mediated bladder cancer treatment.

Rapamycin enhances growth inhibition on urothelial carcinoma cells through LKB1 deficiency-mediated mitochondrial dysregulation.

Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, has significant potential for application in the treatment of urothelial carcinoma (URCa) of the bladder. Previous studies have shown that regulation of the AMP-activated serine/threonine protein kinase (AMPK)-mTOR signaling pathway enhances apoptosis by inducing autophagy or mitophagy in bladder cancer. Alteration of liver kinase B1 (LKB1)-AMPK signaling leads to mitochondrial dysfunction and the accumulation of autophagy-related proteins as a result of mitophagy, resulting in enhanced cell sensitivity to drug treatments. Therefore, we hypothesized that LKB1 deficiency in URCa cells could lead to increased sensitivity to rapamycin by inducing mitochondrial defect-mediated mitophagy. To test this, we established stable LKBI-knockdown URCa cells and analyzed the effects of rapamycin on their growth. Rapamycin enhanced growth inhibition and apoptosis in stable LKB1-knockdown URCa cells and in a xenograft mouse model. In spite of the stable downregulation of LKB1 expression, rapamycin induced AMPK activation in URCa cells, causing loss of the mitochondrial membrane potential, ATP depletion, and ROS accumulation, indicating an alteration of mitochondrial biogenesis. Our findings suggest that the absence of LKB1 can be targeted to induce dysregulated mitochondrial biogenesis by rapamycin treatment in the design of novel therapeutic strategies for bladder cancer.