Fig. 6: Verification of the specific role of SAA1 in lung cancer bone metastasis supported by the data of clinical cohorts.

a Schematic figure validating the role in lung cancer bone metastasis clinically. For the first validation cohort, three paired lung adenocarcinoma samples of primary and bone metastatic lesions were collected and analyzed through scRNA-seq. For the second validation cohort, 20 lung adenocarcinoma bone metastatic lesions were collected, and eight of them were analyzed through bulk RNA-seq and compared with the normal bone tissues from healthy controls, while IHC staining was conducted on the remaining 12 samples to confirm the expression of SAA1, YWHAE, EEF2, PSMB6, and RPS3A. Created in BioRender. Wen, Y. (2024) BioRender.com/c79s395. b UMAP plot demonstrating 19 cancer cell clusters. c UMAP plot of cancer cells, grouped by cell origin. d The major cell cluster constituents in lung or bone metastatic samples. e The expression percentage of SAA1 in each cancer cell cluster. f The variation of expression percentage of SAA1 in each cancer cell cluster and total cancer cell clusters from primary to bone metastatic lesions. g The heatmaps illustrated that many of the DNB genes prefiguring bone metastasis, including SAA1, were highly enriched in cancer cell clusters of bone metastatic lesions. h For the second validation cohort, the expression Log₂foldchange of the DNB genes indicating different metastases was examined, and SAA1 was the only gene denoting a Log₂foldchange of ~10 times between bone metastatic lesions and normal bone tissues. i The IHC staining results of SAA1 (1), YWHAE (2) PSMB6 (3), RPS3A (4), and EEF2 (5) in bone metastatic lesions in the second validation cohort and their corresponding statistical analysis (6), with n = 12 in each group. The data were presented as mean ± SD; P < 0.001 for the comparison between SAA1 and others. One-way ANOVA was performed to make inter-group comparison. j The serum level of SAA1 in groups of healthy controls (n = 30), bone (n = 10), "Brainplus" (n = 14), lung (n = 12), pleura (n = 11); P value for inter-group comparison was listed as follows: bone-healthy volunteers: P = 0.01; bone-Brainplus: P = 0.008; bone-lung: P = 0.005; bone-pleura: P = 0.005 (1); and YWHAE in groups of bone (n = 10), brainplus (n = 12), lung (n = 12), pleura (n = 11) were comparatively analyzed, with P value for inter-group comparison was listed as follows: bone-Brainplus: P = 0.305; bone-lung: P = 0.860; bone-pleura: P = 1.000 (2). The data were presented as mean ± SD. One-way ANOVA and Dunnett’s test corrections were performed to make inter-group comparison. *P < 0.05; **P < 0.01; ***P < 0.001; ns: not significant. Bone mets.: Bone metastasis.