Impact of Calu-6 cell density on expression of <i>TERT</i> splice variants.

A) Representative phase contrast micrograph images 24 hours after seeding. The number of seeded Calu-6 cells are indicated. Scale bar for image is 1000 μm. B,C, and E-K) Expression of TERT splice variants are reduced with higher cell density. Potential FL (B), minus beta (C), minus alpha (E), INS3 (F), INS4 (G), minus gamma (H), plus gamma (I), intron 11 retention (J), and intron 14 retention (K) transcripts were quantified (determined by ddPCR; n = 6 biological replicates per condition). D) Exons 7/8 alternative splicing ratio did not change significantly in different cell densities. L) Telomerase activity in different cell densities (determined by ddTRAP; n = 6 biological replicates per condition). One-way ANOVA with uncorrected Fisher’s LSD for post hoc comparisons were used to compare medium (Med) and high-density (High) conditions with low-density (Low) condition (B-L; ns, P > 0.05; *, P P P P < 0.0001). Data are presented as means ± standard deviations where applicable.