Stress signaling in breast cancer cells induces matrix comp. that promote chemoresistant metastasis (2018)
Figure 4

Figure 4. SPP1 and TNC are induced by active JNK and promote lung metastasis.

A SPP1 and TNC expression in the indicated breast cancer cells treated with increasing concentrations of JNKi.

B SPP1 and TNC expression in MDA231-LM2 cells transduced with pLVX-puro lentivirus without a transgene (control) or expressing constitutively-active JNK (MKK7-JNK) or mutated inactive JNK (MKK7-JNK(mut)).

C SPP1 and TNC expression in pleural effusion (1 and 2) and ascites (3 and 4) samples from four different patients treated with JNKi (4 μM, 48h) in culture. Values are mean ± SD from triplicates. The results from all four patient samples were included to calculate significance of JNKi on gene expression. SPP1, P = 0.0079; TNC, P = 0.0002. P values were determined by two tailed paired Student's t test.

D Analysis of SPP1 and TNC mRNA levels in SUM159-LM1 cells grown as monolayer or spheres and treated with vehicle or JNKi. For panels A-D, values represent the mean of qPCR triplicates ± SD.

E, F ChIP analysis of c-Jun binding to sequences in SPP1 or TNC promoters. (E) Diagrams of SPP1 and TNC promoters showing positions of primer pairs, flanking c-Jun/AP-1 consensus sites, that were used for qPCR following ChIP with an antibody against c-Jun. (F) Analysis of SPP1 and TNC promoter fragments pulled down by c-Jun and IgG antibodies. Values represent the mean of qPCR triplicates ± SD.

G Correlation analysis of SPP1 and TNC with JUN expression in dissected metastatic nodules from breast cancer patients (GSE14020). N = 65 metastasis samples. P values were acquired by two-tailed Student's t test.

H, I Lung metastasis in Spp1+/- mice implanted with MDA231-LM2 cells expressing control shRNA (control), and Spp1-/- mice implanted with MDA231-LM2 cells independently expressing one of two different SPP1 shRNAs (SPP1-deficient). Ex vivo lung luminescence was analyzed, panel H. Boxes show the median value with upper and lower quartiles. Whiskers represent minimum and maximum values. Control n = 16 mice, SPP1 deficient (1) n = 14 mice and SPP1 deficient (2) n = 15 mice. P values were determined by a two-tailed Mann-Whitney test. (I) Representative histological images of metastatic foci (top) and ex vivo lung bioluminescence (bottom). In histological samples, immunohistochemistry was used to determine metastatic nodules based on expression of human vimentin (arrows). Scale bar, 100 µm.

J, K SUM159-LM1 cells expressing either control shRNA (control), or one of two different TNC shRNAs (shTNC 1 and 2), were injected intravenously into NSG mice. (J) Metastatic colonization was quantified by lung bioluminescence. Control and shTNC (1) n = 8 mice per group, shTNC (2) n = 7 mice. P value was determined by a two-tailed Mann-Whitney test. (K) Representative images of metastatic foci (top) and ex vivo lung bioluminescence (bottom). Arrows denote vimentin-expressing cancer cells in metastases. Scale bar, 100 µm.

L Kaplan-Meier analysis of breast cancer patients (combined GSE2603 and GSE5327 datasets) showing a link between high SPP1 and TNC expression and poor lung metastasis-free survival. Patient samples, SPP1 and TNC low n = 70; SPP1 and TNC high n = 70. HR, Hazard ratio. P value was determined by log-rank test.