Olfactomedin 4 mediation of prostate stem/progenitor-like cell proliferation and differentiation via MYC.

Olfactomedin 4 (OLFM4) is expressed in normal prostate epithelial cells and immortalized normal human prostate epithelial cells (RWPE1), but the identity of OLFM4-expressing cells within these populations and OLFM4’s physiological functions in these cells have not been elucidated. Using single-cell RNA sequencing analysis, we found here that OLFM4 was expressed in multiple stem/progenitor-like cell populations in both the normal prostate epithelium and RWPE1 cells and was frequently co-expressed with KRT13 and LY6D in RWPE1 cells. Functionally, OLFM4-knockout RWPE1 cells exhibited enhanced proliferation of the stem/progenitor-like cell population, shifts stem/progenitor-like cell division to favor symmetric division and differentiated into higher levels PSA expression cells in organoid assays compared with OLFM4-wild RWPE1 cells. Bulk-cell RNA sequencing analysis pinpointed that cMYC expression were enhanced in the OLFM4-knockout RWPE1 cells compared with OLFM4-wild cells. Molecular and signaling pathway studies revealed an increase in the WNT/APC/MYC signaling pathway gene signature, as well as that of MYC target genes that regulate multiple biological processes, in OLFM4-knockout RWPE1 cells. These findings indicated that OLFM4 is co-expressed with multiple stem/progenitor cell marker genes in prostate epithelial cells and acts as a novel mediator in prostate stem/progenitor cell proliferation and differentiation.

嗅介蛋白4（OLFM4）在正常前列腺上皮细胞和永生化的正常人前列腺上皮细胞（RWPE1）中表达，但这些细胞群中表达OLFM4的细胞的特性以及OLFM4在这些细胞中的生理功能尚未阐明。通过单细胞RNA测序分析，我们在此发现OLFM4在正常前列腺上皮和RWPE1细胞的多个干/祖细胞样细胞群中表达，并且在RWPE1细胞中经常与KRT13和LY6D共表达。在功能上，与野生型OLFM4的RWPE1细胞相比，OLFM4敲除的RWPE1细胞表现出干/祖细胞样细胞群的增殖增强，使干/祖细胞样细胞分裂偏向对称分裂，并且在类器官实验中分化为更高水平表达前列腺特异抗原（PSA）的细胞。大量细胞RNA测序分析明确指出，与野生型OLFM4细胞相比，OLFM4敲除的RWPE1细胞中cMYC表达增强。分子和信号通路研究显示，在OLFM4敲除的RWPE1细胞中，WNT/APC/MYC信号通路基因特征以及调节多种生物学过程的MYC靶基因特征增加。这些发现表明OLFM4在前列腺上皮细胞中与多个干/祖细胞标记基因共表达，并作为前列腺干/祖细胞增殖和分化的一种新型调节因子。