Adipocytes reprogram prostate cancer stem cell machinery

Multifaceted impact of adipose conditioned media: Obesity-driven promotion of prostate cancer and cancer stem cell dynamics

Obesity is an established risk factor for the development and progression of prostate cancer (PC). This study used adipose conditioned media (ACM) from differentiated adipocytes to assess its effect on PC development and aggressiveness. Due to limited research on ACM's impact on isolated PC stem cells (PCSCs), we also examined CD44+ PCSCs. ACM notably boosted interleukin-1β (IL-1β), IL-6, and IL-8 production in normal prostate epithelial cells and LNCaP cells. It also increased IL-6 and IL-8 production in PC3 and CD44+ LNCaP cells, and IL-1β and IL-6 production in CD44+ PC3 cells. This indicates that ACM induces the production of inflammatory cytokines in both cancer and prostate epithelial cells. Furthermore, ACM promoted proliferation in androgen receptor (AR)-negative PC3 cells, CD44+  PC3 PCSCs, and nonmalignant RWPE cells, without affecting AR-positive LNCaP cells. In addition, ACM-enhanced invasion and migration potential in both PC3 and CD44+  PC3 cells. Western blot analysis indicated the involvement of NF-κB and AKT pathways in ACM-induced proliferation in PC3 cells and NF-κB in PCSCs. In ACM-treated PC3 cells, E-cadherin was downregulated, while N-cadherin, Snail, vimentin, fibronectin, and Twist were upregulated, suggesting ACM-induced invasion via classical epithelial-to-mesenchymal transition (EMT) pathways. In response to ACM, PCSCs exhibited increased expression of E-cadherin, Snail, and vimentin, which are partial EMT markers promoting stemness and resistance to apoptosis. In addition, increased expressions of Nanog, Oct3/4, survivin, and Bcl-2 were observed. Although the molecules we studied have diverse effects on cellular regulation, our data emphasize obesity's multifaceted role in promoting and aggressing PC, notably affecting PCSC populations.

MMP11 and MMP14 contribute to the interaction between castration-resistant prostate cancer and adipocytes

Previous studies have demonstrated that adipocytes promote prostate cancer (PCa) cell progression, which facilitates the development of PCa into castration-resistant prostate cancer (CRPC); however, the underlying mechanisms are still not fully understood. Matrix metalloproteinases (MMPs) are a group of proteases responsible for the degradation of extracellular matrix (ECM) and the activation of latent factors. In our study, we detected that MMP11 expression was increased in PCa patients and that a high level of MMP11 was correlated with poor prognosis. Furthermore, siRNA knockdown of MMP11 in CRPC cells not only blocked the delipidation and dedifferentiation of mature adipocytes but also reduced the lipid uptake and utilization of CRPC cells in a cell co-culture model. The number of mitophagosomes and the expression level of Parkin were increased in MMP11-silenced CRPC cells. Moreover, we found that simultaneous downregulation of MMP14 and MMP11 expression may benefit patient survival. Indeed, MMP11/14 knockdown in CRPC cells significantly decreased lipid metabolism and cell invasion, at least partly through the mTOR/HIF1α/MMP2 signaling pathway. Importantly, MMP11/14 knockdown dramatically delayed tumor growth in a xenograft mouse model. Consistently, the decreased lipid metabolism, Ki67 and MMP2 expression, as well as the increased Parkin level were also confirmed in in vivo experiments, further demonstrating the mechanisms responsible for the tumor-promoting effects of MMP11/14. Collectively, our study elucidated the role of MMP11 and MMP14 in the bidirectional crosstalk between adipocytes and CRPC cells and provided the rationale of targeting MMP11/14 for the treatment of CRPC patients.

Exploring the role of the inflammasomes on prostate cancer: Interplay with obesity

Obesity is a weight-related disorder characterized by excessive adipose tissue growth and dysfunction which leads to the onset of a systemic chronic low-grade inflammatory state. Likewise, inflammation is considered a classic cancer hallmark affecting several steps of carcinogenesis and tumor progression. In this regard, novel molecular complexes termed inflammasomes have been identified which are able to react to a wide spectrum of insults, impacting several metabolic-related disorders, but their contribution to cancer biology remains unclear. In this context, prostate cancer (PCa) has a markedly inflammatory component, and patients frequently are elderly individuals who exhibit weight-related disorders, being obesity the most prevalent condition. Therefore, inflammation, and specifically, inflammasome complexes, could be crucial players in the interplay between PCa and metabolic disorders. In this review, we will: 1) discuss the potential role of each inflammasome component (sensor, molecular adaptor, and targets) in PCa pathophysiology, placing special emphasis on IL-1β/NF-kB pathway and ROS and hypoxia influence; 2) explore the association between inflammasomes and obesity, and how these molecular complexes could act as the cornerstone between the obesity and PCa; and, 3) compile current clinical trials regarding inflammasome targeting, providing some insights about their potential use in the clinical practice.

Adipocyte regulation of cancer stem cells

Cancer stem cells (CSCs) are a highly tumorigenic subpopulation of the cancer cells within a tumor that drive tumor initiation, progression, and therapy resistance. In general, stem cell niche provides a specific microenvironment in which stem cells are present in an undifferentiated and self-renewable state. CSC niche is a specialized tumor microenvironment for CSCs which provides cues for their maintenance and propagation. However, molecular mechanisms for the CSC-niche interaction remain to be elucidated. We have revealed that adipsin (complement factor D) and its downstream effector hepatocyte growth factor are secreted from adipocytes and enhance the CSC properties in breast cancers in which tumor initiation and progression are constantly associated with the surrounding adipose tissue. Considering that obesity, characterized by excess adipose tissue, is associated with an increased risk of multiple cancers, it is reasonably speculated that adipocyte-CSC interaction is similarly involved in many types of cancers, such as pancreas, colorectal, and ovarian cancers. In this review, various molecular mechanisms by which adipocytes regulate CSCs, including secretion of adipokines, extracellular matrix production, biosynthesis of estrogen, metabolism, and exosome, are discussed. Uncovering the roles of adipocytes in the CSC niche will propose novel strategies to treat cancers, especially those whose progression is linked to obesity.