Journal: Cancers
Article Title: Exosome-Mediated Activation of the Prostasin-Matriptase Serine Protease Cascade in B Lymphoma Cells.
doi: 10.3390/cancers15153848
Figure Lengend Snippet: Figure 6. Impact of prostasin–matriptase cascade activation on B cancer cells. (a) Bar graph of cell count for two consecutive days of B cells treated with exosomes. Namalwa, n = 7; Ramos, n = 6; Raji, n = 5; Jeko-1, n = 6. * denotes p < 0.05. (b) Growth curves of NamalwaTR-Vec and NamalwaTR-Pro cells under tetracycline induction. Left graph, cells were set at 2.5 × 105/mL on day 0 and cultured in the growth medium containing 10%FBS for 4 days. Right graph, on day 4 (reset, indicated by the arrow), the cells were diluted in OPTI-MEM I/2%FBS to 5 × 105/mL and cultured for another 5 days. Tetracycline at 1 µg/mL was added into the culture on day 0 and maintained through culturing. n = 4 for each cell line, and * denotes p < 0.05. (c) Trypsin-like serine protease activity in the conditioned media of NamalwaTR-Vec and NamalwaTR-Pro cells (n = 4). Data were analyzed in Excel with student’s t test. * denotes p < 0.05 between the two sample groups. (d) Bar graph of annexin-V-positive cells analyzed by flow cytometry. Cells under tetracycline induction were cultured for various times (week 1, n = 3; week 2, n = 4; week 3, n = 3) and subjected to direct labeling of annexin V conjugated with fluorophore allophycocyanin (APC). Ten thousand cells for each sample were analyzed on the CytoFLEX S flow cytometer. Propidium iodide staining and FSC/SSC discrimination were used for gating the live singlets, which were further analyzed for annexin V staining. (e) Bar graph of migrated cells treated with exosomes for 24 h. * denotes p < 0.05. (f) Bar graph of migrated Namalwa sublines with the induction of prostasin expression for 2–4 days and reconditioned in RPMI medium for 1 day before seeding in Transwells for migration (n = 7). * denotes p < 0.05. (g) Bar graph of invaded cells treated with exosomes for 24 h. (h) Bar graph of invaded Namalwa sublines (n = 5) treated as in (f). * denotes p < 0.05. (i) Gelatin zymography and western blot analysis. Top panel, the Ramos cells (2 × 106) in 500 µL of RPMI/0.1%BSA were treated with vector exosomes (Vexo), prostasin exosomes (Pexo), or a purified recombinant human matriptase serine protease domain (r-Mat SPD) overnight. One-fifth of the cell lysate (lanes 1–3) or 20 µL of the conditioned medium (lanes 4–6) were analyzed. The Vexo or Pexo exosomes or the r-Mat SPD alone were incubated in RPMI/0.1%BSA and used as controls (lanes 7–9). The clear bands at ~70 kDa marked by a filled arrow are matriptase. These were recognized by matriptase antibodies (middle panel). Unidentified bands with gelatinase activity marked at * locations in lanes 4, 5, 7, 8 are inherited from the exosomes, as shown in the samples with the exosomes alone (lanes 7 and 8). The band marked by the white circle is unknown. Bands at ~28 kDa marked by an unfilled arrow are r-Mat SPD. Bottom panel is GAPDH, which is detected only in the cell lysate, not in media samples or the controls without cells. (j) Gelatin zymography of B cancer cells treated as described in (i). The matriptase gelatinase activity is decreased in the cell lysate (lanes 2, 6, 10, 14) but increased in the corresponding media samples (lanes 4, 8, 12, 16) upon Pexo treatment in comparison to that of the Vexo-treated samples (in lysate, lanes 1, 5, 9, 13; in media, lanes 3, 7, 11, 15), correspondingly.
Article Snippet: A purified recombinant human matriptase serine protease domain (r-Mat SPD, R&D Systems), when added (0.2 nM) in the Ramos cell culture, also reduced the quantity of the endogenous matriptase (Figure 6i, middle panel, lane 3) and the gelatinase activity of the endogenously expressed matriptase (Figure 6i, top panel, lane 3), suggesting that the soluble active matriptase can further activate more cellular matriptase zymogen.
Techniques: Activation Assay, Cell Counting, Cell Culture, Activity Assay, Cytometry, Labeling, Staining, Expressing, Migration, Zymography, Western Blot, Plasmid Preparation, Recombinant, Incubation, Comparison