Fig. 3. NCAM1 is a PPB key regulatory molecule.

a qRT-PCR analysis revealed high NCAM1 expression in primary PPB tumor (n = 3) in comparison to healthy adult lung control sample (n = 3) (top) and in late passages. (n = 3) in comparison to primary tumor (bottom); *p < 0.01; Mann–Whitney U test. b FACS analysis revealed that in early passage PDX cells (P2), only 20% of cells were NCAM1⁺ in comparison to 76% of cells in late passage (P10). c IHC staining demonstrating an increased expression of NCAM1 along the passages; Scale bar, 100 μm. d qRT-PCR analysis reveals high gene expression of several self-renewal genes (e.g., BMI1, EZH2, OCT4 and KLF4) in the NCAM1⁺ cells; For qRT-PCR analyses the values of primary tumor cells were used to normalize (therefore = 1) and all other values were calculated accordingly. Results are presented as the mean ± S.E.M of three separated experiments. *p < 0.05, **p < 0.01. e IHC staining demonstrating NCAM1 expression in four different PPB primary tumors; Positive NCAM1 expression was estimated at 10% (tumors 1 and 2), 20% (tumor 3), and 30% (tumor 4) of primary tumor cells. Scale bar, 100 μm