According to previous studies, luminal and basal cells are the possible initiating cells of PCa [
17]. UMAP analysis of luminal cells identified a total of seven subgroups (Fig.
2A) and demonstrated gene expression patterns in different luminal cell subgroups (Fig.
2B, Supplementary Material 13). The top five merker genes in each subgroup of luminal cells were also demonstrated (Fig.
2C), which were
EEF1A2, HBB, IGKC, NPY, and FOLH1 in the luminal 1. HBB and IGKC were highly expressed in the luminal 5, while NPY and FOLH1 were highly expressed in the luminal 7 (Fig.
2C). GSVA showed that MYC and oxidative phosphorylation signaling pathways were enriched in the luminal 1 subgroup, while TNF-α signaling pathway activity was enhanced in the luminal 3 subgroup. In addition, the luminal 4 subgroup had high protein secretion and androgen response pathway enrichment score, while the E2F and G2M signaling pathways were enriched in the luminal 6 subgroup. The luminal 7 subgroup demonstrated enhanced activity in the angiogenesis signaling pathway (Fig.
2D).
The InferCNV algorithm was used to identify chromosomal CNAs to further verify the presence of malignant cells in the seven luminal subgroups. As described previously [
18], this method can identify typical PCa genomic alterations [
10,
19], including the chromosome 8q gain and chromosome 8p, 13, and 16q loss. Chen et al. found that only an inflection point was observed in a few PCa samples, which can separate putative malignant cells from non-malignant cells in PCa. However, this distinction was not so precise in other samples [
17], which may be because some localized PCa tumors have been shown to have a silent genome [
20]. Furthermore, previous DNA sequencing studies have revealed that 0–50% of PCa genomes have CNAs and that CNAs are also a prognostic factor for PCa [
21]. Moreover, the subclone CNA load far exceeds the clonal load in most PCa cases [
22]. The InferCNV results of our study are shown in Fig.
2E. All cells in the luminal subgroups 1 and 5, as well as 3 and 7, were clustered together. All cells in the other subgroups were grouped separately (Fig.
2E). In the CNA heatmap, red and blue represent excessive and low gene expression values in the fragment chromosomes, respectively. This means that the darker the red color, the higher the degree of chromosome amplification, and the darker the blue color is, the higher the degree of chromosome loss. Therefore, the study results showed that luminal subgroups 1 and 5, as well as 3 and 7, had a much higher degree of chromosome CNAs than other clusters. Therefore, cells in the luminal subgroups 1 and 5, as well as 3 and 7, may be malignant ones (Fig.
2E). Furthermore, luminal subgroups 1 and 5 only appeared in metastatic lesions, implying that these two subgroups may contain cells with metastatic ability among the malignant cells (Fig.
2G). The DEGs and their functional enrichment between primary lesion and LNM were further analyzed to reveal specific gene expression patterns of LNM in PCa (Fig.
2H-I, Supplementary Material 14). The results showed that the main enriched functional DEG pathways were immune-related, such as regulation of leukocyte and lymphocyte activity and B cell activity (Fig.
2I), indicating that tumor immunity may contribute to lymphatic metastasis in PCa. Furthermore, the transcriptional regulators of luminal cells were analyzed and compared between primary lesions and LNM (Fig.
2F and J). JDP2, IRF1, ENO1, HOXB2, IRF8, NELFE, ESRRA, SP8, KLF9, SF1, TFAP2A, IRF7, CREB3, GTF2F1, MXI1, CREB5, EGR3, FOXO3, NFATC3, and CREM were all activated in LNM, but not in the primary lesions (Fig.
2F and J; Supplementary Fig.
1A–G). In particular, the expression of NELFE in lymphatic metastases was significantly higher than that in the primary lesion. It has been reported that NELFE can promote the invasion and metastasis in many cancers. Therefore, the above results demonstrated that these TFs may be involved in lymphatic metastasis of PCa (Fig.
2J, Supplementary Fig.
1H). Subsequently, markers gene EEF1A2 and CCL5 with specificity in EEF2 + and FOLH1 + luminal subgroups were selected for immunohistochemical staining on our PCa tissue chips, and the results showed negative results in normal tissues.The positive expression of some PCa cells in the primary and lymphatic metastases suggests the existence of these two subgroups of cells in PCa (Fig.
3A). Immunofluorescence demonstrated that MEEF1A2 and CCL5 were all expressed in LNCap cells (Fig.
3B). Down-regulating the expression of MEEF1A2 and CCL5 in LNCap cells could significantly reduced the ability of cell proliferation and metastasis ((Fig.
3C-F).