The olfactory receptor OR51E2 regulates prostate cancer aggressiveness and modulates STAT3 in prostate cancer cells and in xenograft tumors

Despite significant advancements in prostate cancer detection and treatment, the molecular mechanisms driving its progression remain elusive. This study aimed to explore the role of the receptor OR51E2, which is frequently upregulated in prostate cancer, in the disease's progression. Using CRISPR-Cas9 technology, we generated monoclonal OR51E2 knockout cells to investigate the receptor's physiological effects. We assessed the tumorigenic potential of these cells both in vitro and in vivo, and conducted transcriptomic and proteomic analyses on xenograft tumors derived from the knockout cells. Additionally, we examined how varying levels of OR51E2 expression in patients from a TCGA cohort impacted disease outcomes. The OR51E2-knockout cells displayed increased proliferation, migration, adhesion, anchorage-independent colony formation, and tumor growth, leading to a more aggressive cancer phenotype. Omics analyses identified several pathways associated with significant molecular changes, particularly an aberration in the STAT3 pathway linked to IL-6 signaling, underscoring a connection to inflammatory pathways. Analysis of the TCGA cohort further revealed that prostate cancer patients with lower OR51E2 expression had worse prognoses and higher average Gleason grades compared to those with higher expression levels. This analysis also supported a role for OR51E2 in modulating the STAT3 pathway within the cohort. Overall, our findings suggest that OR51E2 plays a critical role in regulating prostate cancer progression by influencing cancer cell physiology and aggressiveness. Reduced OR51E2 expression may lead to poorer patient outcomes, potentially through disruptions in the STAT3 pathway that alter cellular responses to inflammatory signaling. Overall design: To investigate the effects of OR51E2 on in vivo prostate cancer tumor growth, we designed a stable, monoclonal OR51E2-knockout LNCaP-derived cell line. LNCaP WT or OR51E2-KO cells were injected subcutaneously in male CIEA NOG mice and were allowed to grow to a size og 1000 mm3, where the tumors were harvested and snap frozen. Total RNA was extracted from these tumors, sequenced, and the expression data was analyzed (mouse reads removed prior to analysis). 9 WT tumors and 8 KO tumors were analyzed.

尽管前列腺癌的检测与治疗已取得显著进展，但其进展背后的分子机制仍不甚明晰。本研究旨在探究在前列腺癌中常呈高表达的受体OR51E2（OR51E2）在疾病进展中的作用。本研究借助CRISPR-Cas9技术构建了单克隆OR51E2敲除细胞系，以探究该受体的生理学功能。我们分别在体外与体内环境中评估了该细胞系的致瘤能力，并对敲除细胞系所形成的异种移植瘤开展转录组与蛋白质组学分析。此外，我们还分析了癌症基因组图谱（TCGA, The Cancer Genome Atlas）队列中患者体内OR51E2表达水平的差异对疾病转归的影响。
OR51E2敲除细胞的增殖、迁移、黏附能力以及非锚定依赖性集落形成能力与体内肿瘤生长能力均有所增强，表现出更具侵袭性的癌症表型。多组学分析鉴定出多个伴随显著分子改变的信号通路，其中尤以与白细胞介素6（IL-6）信号通路相关的信号转导与转录激活因子3（STAT3）通路异常最为突出，提示该受体与炎症通路存在关联。对TCGA队列的进一步分析显示，与OR51E2高表达的前列腺癌患者相比，OR51E2低表达患者的预后更差，平均格里森评分（Gleason grade）更高。该分析结果进一步证实，OR51E2在该队列中可调控STAT3信号通路。
综上，本研究结果表明，OR51E2可通过影响癌细胞的生理状态与侵袭能力，在前列腺癌进展过程中发挥关键调控作用。OR51E2表达下调可能通过破坏STAT3通路、改变细胞对炎症信号的应答，进而导致患者预后不良。
实验整体设计：为探究OR51E2对前列腺癌体内生长的影响，本研究构建了稳定的单克隆OR51E2敲除LNCaP源细胞系。将LNCaP野生型（WT）或OR51E2敲除（KO）细胞接种至雄性CIEA NOG小鼠皮下，待肿瘤生长至1000 mm³时收获肿瘤并快速冷冻保存。从上述肿瘤中提取总RNA并进行测序，随后对表达数据进行分析（分析前已剔除小鼠源测序读段）。本研究共分析9个野生型组肿瘤样本与8个敲除组肿瘤样本。