Figure 5

Association of SNAI2 and ERα expression with metastasis. A cohort of 557 BCa tumors compiled from the GEO datasets GSE2034, GSE2603 and GSE12276 [37–39], was dichotomized into groups expressing either high or low levels of either SNAI2 or ESR1/ERα, and Kaplan-Meier curves were constructed for the probability of overall or organ-specific metastasis-free survival in each group. (A-D) Kaplan-Meier curves of overall, brain, lung and bone metastasis-free survival in the cohort of 557 patients according to SNAI2 expression status. (E-H) Kaplan-Meier curves of overall, brain, lung and bone metastasis-free survival in the cohort according to ERα expression status.(I-L) Kaplan-Meier curves of overall, brain, lung and bone metastasis-free survival were generated for the 342 ERα-positive (black and grey curves) and 215 ERα-negative (blue and pink curves) tumors based on high versus low expression of SNAI2. Significance of association was determined by logrank test and the P-values are depicted for ERα-positive (green), and ERα-negative tumors (red). (M-Q) Expression status of SNAI2 and ERα in tumors that either have not relapsed (M) or metastasized to any tissue (N), to brain (O), to lung (P), or to bone (Q). (R) Expression of SNAI2 mRNA in lung-seeking tumors expressing ESR1/ERα at high versus low levels. The difference is significant (*, P < 0.05) based on unpaired t-test with Welch correction of the log2-transformed signal intensities. (S) Expression of SNAI2 mRNA in bone-seeking tumors expressing ESR1/ERα at high versus low levels. The difference is insignificant (NS, P = 0.23) based on unpaired t-test with Welch correction of the log2-transformed signal intensities. (T-U) Correlation between SNAI2 mRNA and ESR1/ERα mRNA in lung-seeking (T) and bone-seeking (U) tumors with high ERα. Values represent log2 transformed normalized signal intensities. (V) Standardized intensity plot of RUNX2, SNAI2 and ESR1/ERα gene expressions in 58 human BCa metastases. Expression data of metastatic tissues was extracted from the GEO dataset GSE14020 [9]. BCa, breast cancer; ESR1/ER, estrogen receptor alpha; GEO, Gene Expression Omnibus; RUNX2, runt related transcription factor 2; SNAI2, snail homolog 2.