GDC-0980 (apitolisib) treatment with gemcitabine and/or cisplatin synergistically reduces cholangiocarcinoma cell growth by suppressing the PI3K/Akt/mTOR pathway.

Since conventional chemotherapy (gemcitabine and cisplatin) has marginal survival benefit in patients with advanced cholangiocarcinoma (CCA), an effective targeted therapeutic agent is urgently required. Activation of the PI3K/Akt/mTOR signaling pathway is frequently observed in CCA, and thus, PI3K and mTOR are promising therapeutic targets in CCA. Recently a new dual PI3K/mTOR inhibitor GDC-0980 (apitolisib) was introduced. This study was undertaken to examine the activity of apitolisib against CCA cells in vitro and in vivo. Apitolisib treatment strongly reduced Akt and mTOR active phosphorylation levels and attenuated cell growth in two different CCA cell lines (SNU478 and SNU1196). In addition, the cytotoxic activity of apitolisib enhanced the effects of gemcitabine or cisplatin in vitro and increased PARP cleavage. Moreover, we observed these co-treatments significantly reduced colony formation by SNU478 and SNU1196 cells and potently inhibited tumor growth in a mouse xenograft model. The results of the present study show that apitolisib effectively reduces CCA cell growth by suppressing the PI3K/Akt/mTOR pathway. In addition, co-treatments with apitolisib and gemcitabine or cisplatin synergistically enhanced apitolisib activity, which suggests a means of improving the chemotherapeutic sensitivity of CCA.

Protocol for evaluation of tumor-derived exosome-induced cancer cell metastasis in a mouse model.

Exosomes mediate intracellular communication between cancer cells and the local/distant microenvironment, which promotes systemic dissemination of cancer. Here, we present a protocol for tumor-derived exosome isolation and in vivo metastasis evaluation in a mouse model. We describe steps for isolating and characterizing exosomes, establishing a metastatic mouse model, and injecting exosomes into mouse. We then detail hematoxylin and eosin staining and analysis. This protocol can be used to investigate exosome function and identify unexplored metastatic regulators related to exosome biogenesis. For complete details on the use and execution of this protocol, please refer to Lee et al. (2023).1.

Heat shock protein 60 couples an oxidative stress-responsive p38/MK2 signaling and NF-κB survival machinery in cancer cells.

Mitochondria communicate with other cellular compartments via the secretion of protein factors. Here, we report an unexpected messenger role for heat shock protein 60 (HSP60) as a mitochondrial-releasing protein factor that couples stress-sensing signaling and cell survival machineries. We show that mild oxidative stress predominantly activates the p38/MK2 complex, which phosphorylates mitochondrial fission factor 1 (MFF1) at the S155 site. Such phosphorylated MFF1 leads to the oligomerization of voltage anion-selective channel 1, thereby triggering the formation of a mitochondrial membrane pore through which the matrix protein HSP60 passes. The liberated HSP60 associates with and activates the IκB kinase (IKK) complex in the cytosol, which consequently induces the NF-κB-dependent expression of survival genes in nucleus. Indeed, inhibition of the HSP60 release or HSP60-IKK interaction sensitizes the cancer cells to mild oxidative stress and regresses the tumorigenic growth of cancer cells in the mouse xenograft model. Thus, this study reveals a novel mitonuclear survival axis responding to oxidative stress.

Androgen-induced expression of DRP1 regulates mitochondrial metabolic reprogramming in prostate cancer.

Androgen receptor (AR) signaling plays a central role in metabolic reprogramming for prostate cancer (PCa) growth and progression. Mitochondria are metabolic powerhouses of the cell and support several hallmarks of cancer. However, the molecular links between AR signaling and the mitochondria that support the metabolic demands of PCa cells are poorly understood. Here, we demonstrate increased levels of dynamin-related protein 1 (DRP1), a mitochondrial fission mediator, in androgen-sensitive and castration-resistant AR-driven PCa. AR signaling upregulates DRP1 to form the VDAC-MPC2 complex, increases pyruvate transport into mitochondria, and supports mitochondrial metabolism, including oxidative phosphorylation and lipogenesis. DRP1 inhibition activates the cellular metabolic stress response, which involves AMPK phosphorylation, induction of autophagy, and the ER unfolded protein response, and attenuates androgen-induced proliferation. Additionally, DRP1 expression facilitates PCa cell survival under diverse metabolic stress conditions, including hypoxia and oxidative stress. Moreover, we found that increased DRP1 expression was indicative of poor prognosis in patients with castration-resistant PCa. Collectively, our findings link androgen signaling-mediated mitochondrial dynamics to metabolic reprogramming; moreover, they have important implications for understanding PCa progression.