Saatcioglu Lab, Department of Biosciences:
The overall focus of our laboratory is to understand the molecular mechanisms of hormone action, especially that of androgens (testosterone) and estrogens, as well as stress signalling in normal cells. In addition, since these pathways are often hijacked by cancer cells, we study as to how they relate to prostate and breast cancer. To achieve this, we use molecular, biochemical, cellular, and genetic approaches. Part of this work is translational in nature from basic science to the clinic. We thus have collaborations with clinical colleagues in Norway and internationally and have identified a number of potential biomarkers and therapeutic targets for cancer. This MSc project focuses on characterization of stress signaling pathways in prostate cancer cells that may have implications for other cancer types as well.
Background:
Prostate cancer (PCa) is the most common non-cutaneous cancer in men and remains a key challenge for men’s health and a significant economic burden on society (James et al., 2024) (Siegel et al., 2023). Majority of primary prostate tumors are treated successfully by radical prostatectomy or external beam radiotherapy, but often tumors progress to invasive and disseminated disease, and in many cases it is already metastatic at diagnosis (James et al., 2024). Patients with metastatic PCa are treated with androgen deprivation therapy (ADT); whereas the initial response is very high, complete remissions are rare and disease progression resumes after a median of 2-3 years. The emergent castration-resistant PCa (CRPC) generally responds to recently developed androgen receptor (AR) inhibitory drugs, but their effect is transient and resistance develops. AR-independent disease, such as neuroendocrine PCa emerges and at this point no effective therapy exists, with prognosis very unfavorable and a median survival of 18 months. The goal of our laboratory is to provide a detailed mechanistic understanding of stress signaling in PCa cells, which we recently found to be critical for PCa, and to develop biomarkers for disease progression as well as identifying potential therapeutic targets and testing of new therapies.
In this context, we have recently discovered that androgen signaling significantly regulates the endoplasmic reticulum (ER) stress pathways and the cellular response to establish homeostasis, the unfolded protein response (UPR) (Pallmann et al., 2021; Pallmann et al., 2019; Sheng et al., 2015; Sheng et al., 2019) (for reviews, see (Jin and Saatcioglu, 2020; Storm et al., 2016). We found that androgen receptor (AR) directly activated one of the canonical arms of the UPR, inositol-requiring enzyme 1 (IRE1) pathway (Sheng et al., 2015; Sheng et al., 2019). Consistent with the importance of IRE1 signaling in PCa, its genetic or pharmacological inhibition dramatically inhibited PCa growth in vitro and in vivo. In keeping with these observations, IRE1 expression and its gene signature, are deregulated in human PCa specimens. Further molecular characterization of IRE1 signaling in PCa showed that IRE1 pathway is involved in regulating oncogene signaling that drives PCa progression. In addition, we have shown that IRE1 signaling may be involved in CRPC progression and resistance to therapy (Sheng et al., 2019). In our most recent studies, we have shown that IRE1 signaling in PCa cells reshapes the tumor microenvironment to establish an immunosuppressive phenotype (unpublished).
We have also found that one of the other three canonical UPR pathways, mediated by PKR-like ER Kinase (PERK), eukaryotic Translation Initiation Factor 2 alpha (eIF2a), and Activating Transcription Factor 4 (ATF4) signaling, is also required for PCa growth and survival (Pallmann et al., 2019). We found that ATF4 expression is increased in human PCa compared with benign prostate; consistently, siRNA-mediated ATF4 knockdown inhibited PCa growth in vitro and in vivo in multiple PCa models. Parallel global transcriptomic and proteomic analyses of ATF4 knockdown confirmed previously reported target genes, but also identified novel ones; all gene classes were confirmed in rescue experiments with ATF4 re-expression. We have started to characterize the function of ATF4 target genes in PCa some of which provide a feedback loop on PERK pathway regulation (Pallmann et al., 2021), unpublished data).
Figure 1. In PCa cells, the androgen receptor (AR) directly activates IRE1α expression, which splices XBP1 mRNA and allows for XBP1s generation. XBP1s transcriptionally induces c-Myc expression, a potent oncoprotein that contributes to tumor progression (left panel). MKC8866 or siXBP1 inhibit XBP1s production, resulting in a significantly decreased c-Myc levels leading to tumor regression (right panel) (Sheng et al., 2019).
Projects:
As noted above, we have strong evidence for the involvement of UPR signaling on PCa cellular phenotype and disesase progression. Building on our recent findings, we are investigating the possible mechanisms through which IRE1 and PERK signaling arms of UPR increase proliferation and inhibit cell death in PCa. We use both cell lines in vitro, as well as xenografts in immunodeficient and syngeneic mice in vivo, to determine the exact molecular mechanisms that are involved. We have established both genetic manipulation as well as pharmacological targeting of these pathways to evaluate their potential as therapeutic targets/biomarkers in PCa. Molecular details and potential feedback mechanisms within each arm of the UPR are being investigated to discover the molecular details of their regulation. In addition, we are exploring the possibility that these two closely related pathways may crosstalk with each other, which may also be provide nodes of control that can be targeted for improved therapeutic applications. To that end, we are using novel reporter cell lines that we have generated by a precise CRISPR knock-in approach that enable examination of UPR signalling simultaneously as well as genome wide CRISPR screen approaches.
If you join one of these projects, you will gain expertise in the following experimental techniques: mammalian cell culture, siRNA-mediated gene silencing in vitro and in vivo, biochemical assays, qPCR and Western analysis, CRISPR-mediated gene editing, advanced microscopy methods, and experiments in mice, as well as some bioinformatics tools. Since we are a molecular and cell biology laboratory with a keen interest in translation into the clinic, we use a variety of methods, which is one of the strengths of our research environment for a MSc project. In addition, during the weekly lab meetings, everyone take turns (one person per week) to either present her/his work or an article from the field, which will help improve your scientific presentation skills.
You will work closely with a PhD student and/or a postdoctoral fellow for daily guidance for your experiments; we will also have small group meetings every few weeks to discuss the progress in the project. We are especially interested in those students who are already considering a career in science and would like to get experience in an internationally competitive laboratory. For more detailed information on the projects and our laboratory, please see our website at https://saatcioglulab.org. For questions and more information, please do not hesitate to contact Fahri Saatcioglu at fahris@uio.no.
References:
James, N.D., Tannock, I., N'Dow, J., Feng, F., Gillessen, S., Ali, S.A., Trujillo, B., Al-Lazikani, B., Attard, G., Bray, F., et al. (2024). The Lancet Commission on prostate cancer: planning for the surge in cases. Lancet 403, 1683-1722.
Jin, Y., and Saatcioglu, F. (2020). Targeting the Unfolded Protein Response in Hormone-Regulated Cancers. Trends Cancer 6, 160-171.
Pallmann, N., Deng, K., Livgard, M., Nenseth, H.Z., Fazli, L., Rennie, P., Danielsen, H.E., Kahraman, N., Mokhlis, H.M., Ozpolat, B., et al. (2021). MTHFD2 is a novel therapeutic target in prostate cancer. Cancer Res 81, 4066-4078.
Pallmann, N., Livgard, M., Tesikova, M., Zeynep Nenseth, H., Akkus, E., Sikkeland, J., Jin, Y., Koc, D., Kuzu, O.F., Pradhan, M., et al. (2019). Regulation of the unfolded protein response through ATF4 and FAM129A in prostate cancer. Oncogene 38, 6301-6318.
Sheng, X., Arnoldussen, Y.J., Storm, M., Tesikova, M., Nenseth, H.Z., Zhao, S., Fazli, L., Rennie, P., Risberg, B., Waehre, H., et al. (2015). Divergent androgen regulation of unfolded protein response pathways drives prostate cancer. EMBO Mol Med 7, 788-801.
Sheng, X., Nenseth, H.Z., Qu, S., Kuzu, O., Frahnow, T., Simon, L., Greene, S., Zeng, Q., Fazli, L., Rennie, P., et al. (2019). IRE1α-XBP1s pathway promotes prostate cancer by activating c-MYC signaling. Nature Communications 10, 323-334.
Siegel, R.L., Miller, K.D., Wagle, N.S., and Jemal, A. (2023). Cancer statistics, 2023. CA Cancer J Clin 73, 17-48.
Storm, M., Sheng, X., Arnoldussen, Y.J., and Saatcioglu, F. (2016). Prostate cancer and the unfolded protein response. Oncotarget 7, 54051-54066.