Journal: bioRxiv
Article Title: Ionic Regulation of Mechanosurveillance and Metastasis via the MRTFA/KCNMB1 Axis
doi: 10.64898/2026.01.13.699089
Figure Lengend Snippet: (A) Schematic of the experimental approach to qualitatively assess relative amounts of extracellular potassium in the tumor microenvironment. (B) Representative image from a lung section showing accumulated K + in a metastatic lesion. Green triangle points to accumulated [K + ] e . Scale: 50µm. (C) Schematic showing elevated Lamp1+ granules at the immune synapse during antigen mediated cancer cell targeting by OT-I+ CD8+ Cytotoxic T lymphocytes. Graph on the right shows OVA dependent increase in Lamp1+ positivity as a measure of T-lymphocyte granulation under different conditions. Results are representative of 3 independent experiments. (D) Measurements of time to death of a cancer cell after it has been contacted 1:1 by a CD8 + T lymphocyte as determined by PI accumulation in the cancer cell. Data are compiled from 4 independent experiments with. P-values are calculated by Kruskal-Wallis test with multiple comparisons. Mean values are shown. ***:P<0.001, ****:P<0.0001. Control = 119 cells, high [K + ] e = 117 cells, BMS = 107 cells, high [K + ] e +BMS = 109 cells. (E) AFM stiffness measurements of representative cancer cells treated with high [K + ] e (45 mM KCl) compared to control. Results are from 2 combined experiments. AT-3: Control = 30 cells, high [K + ] e = 33 cells; E0771: Control = 34 cells, high [K + ] e = 37 cells. Mann-Whitney test. All error bars are mean±s.e.m. ns, not significant; *P<0.05; **P<0.01; ***P<0.001. (F) AFM stiffness measurements of representative cancer cells treated with high [K + ] e and with/without 10 µM BMS-204352. Results are from 2 combined experiments. AT-3: high [K + ] e =25 cells, high [K + ] e +BMS = 21 cells; E0771: high [K + ] e = 20 cells, high [K + ] e +BMS = 20 cells. Mann-Whitney test. All error bars are mean±s.e.m. ns, not significant; *P<0.05; **P<0.01; ***P<0.001. (G) Schematic depiction of how cortical F-actin influences surface roughness and the surface roughness measurements performed by AFM. Data is combined from 4 independent experiments. AT-3: Control = 28 cells, high [K + ] e = 28 cells, BMS = 24 cells, high [K + ] e +BMS = 24 cells, E0771: Control = 23 cells, high [K + ] e = 25 cells, BMS = 24 cells, high [K + ] e +BMS = 23 cells. P-values calculated by Mann-Whitney rank sum test. Mean+/-s.e.m are shown. RMS: root-mean square. (H) Cell height of cells used in (G) measured by AFM. (I) Venn diagrams showing the number of differentially regulated genes in high [K + ] e . The intersections represent the genes “rescued” which means the BMS-204352 treatment caused differential expression in the opposite direction. “Commonly rescued” genes are conserved across two different cell types. (J) Gene ontology analyses of “Commonly rescued” genes in (F). See Table S6 for a full list of GO terms that are enriched. (K) Working model: MRTFA/SRF upregulates the expression of F-actin bundling proteins and BK channel subunit, KCNMB1, for promoting cellular stiffness. Elevated cancer cell stiffness triggers mechanosurveillance by cytotoxic lymphocytes for inhibiting metastatic colonization.
Article Snippet: TaqMan probes used were all purchased from Thermo Scientific: Gapdh (Mm99999915_g1), Acta2 (Mm00725412_s1), Actg2 (Mm00656102_m1), Tagln (Mm00441661_g1), Myh11 (Mm00443013_m1) , Mrtfa (Mm00461840_m1), Mrtfb (Mm00463877_m1), Srf (Mm00491032_m1), Kcnmb1 (Mm00466621_m1), Ccn2 (Mm01192933_g1), GAPDH (Hs99999905_m1), MRTFA (Hs01090249_g1), MRTFB (Hs00401867_m1), SRF (Hs00182371_m1), KCNMB1 (Hs00188073_m1).
Techniques: Control, MANN-WHITNEY, Quantitative Proteomics, Expressing