Single‐cell RNA‐seq dissecting heterogeneity of tumor cells and comprehensive dynamics in tumor microenvironment during lymph nodes metastasis in gastric cancer

Abstract

Lymph node metastasis is the common metastasis route of gastric cancer. However, until now, heterogeneities of tumor cells and tumor microenvironment in primary tumors (PT) and metastatic lymph nodes (MLN) of gastric cancer (GC) remains uncharacterized. In our study, single cell RNA sequencing was performed on tissues from PT and MLN of gastric cancer. Trajectory analysis and function enrichment analyses were conducted to decode the underlying mechanisms contributing to LN metastasis of gastric cancer. Heterogeneous composition of immune cells and distinct intercellular interactions in PT and MLN were analyzed. Based on the generated single cell transcriptome profiles, dynamics of gene expressions in cancer cells between PT and MLN were characterized. Moreover, we reconstructed the developmental trajectory of GC cells' metastasis to LN and identified two subtypes of GC cells with distinct potentials of having malignant biological behaviors. We characterized the repression of neutrophil polarization associated genes, like LCN2, which would contribute to LN metastasis, and histochemistry experiments validated our findings. Additionally, heterogeneity in neutrophils, rather than macrophages, was characterized. Immune checkpoint associated interaction of SPP1 was found active in MLN. In conclusion, we decode the dynamics of tumor cells during LN metastasis in GC and to identify a subtype of GC cells with potentials of LN metastasis. Our data indicated that the disordering the neutrophils polarization and maturation and the activation of immune checkpoint SPP1 might contribute to LN metastasis in GC, providing a novel insight on the mechanism and potential therapeutic targets of LN metastasis in GC.

Reprogramming of sentinel lymph node microenvironment during tumor metastasis

“…Our results showed that angiogenesis-related gene sets were significantly upregulated in Cd4 + , and Cd8 + T-cells and Tregs. Consistent with our findings, a recent study demonstrated an increase in the proportion of T cells, B cells, DCs and natural killer (NK) cells in metastatic lymph nodes [ 67 ]. Interestingly, the accumulation of N2 type neutrophil (Cd54 low ) was significantly enhanced.…”

Multi‐omics analyses reveal spatial heterogeneity in primary and metastatic oesophageal squamous cell carcinoma

“…61 Qian et al revealed the heterogeneities of the TME in primary tumours and metastatic LNs of gastric cancer. 62 Liu et al generated single-cell maps of PT and paired LN met in eight patients with breast cancer and reported that B and CD4 T cells were enriched in the microenvironment of LN met ; however, CD8 T cells, cancer-associated fibroblasts and mast cells were abundant in PT. 63 TME heterogeneity between the primary tumour and locoregional metastases in the same patient may account for differences in response to immunotherapy.…”

The double‐edged role of neutrophil heterogeneity in inflammatory diseases and cancers

“…Through single‐cell RNA sequencing, researchers from another team mapped the lymph node metastasis landscape of GC and found that lipocalin 2 (LCN2) + neutrophils served as a promotor in lymph node metastasis. This suggested that neutrophil subsets might drive metastatic in specific tumor sites 291 . The number of PD‐L1 + neutrophils and CD66b + neutrophils are associated with the survival of GC patients 292–294 .…”

“…Targeting tumor‐associated CXCR2 + neutrophils and CCR2 + macrophages was reported to improve chemotherapeutic responses in pancreatic ductal adenocarcinoma 342 . In a nutshell, a series of studies have shown that it is necessary to investigate neutrophil heterogeneity in the context of pancreatic cancer treatment 266–343 . For subsequent investigation, the inductive factors of the emergence of diverse neutrophil subsets may be probed, enabling a brand‐new viewpoint for the treatment of pancreatic cancer.…”