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PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
One-way ANOVA with a post-hoc test was performed to compare multiple means (*p < 0.05, **p < 0.01, ***p < 0.001).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Error bars in G and H represent the standard deviation (SD) of the mean of three independent western blots.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
A, B Immunocytochemistry (ICC) analysis of KIT expression in gastrointestinal stromal tumor (GIST) (GIST430 and GIST882) and colon cancer (CC) cells (DLD-1 and Colo320DM) with or without permeabilization using triton X-100.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
C ICC analysis of KIT and calnexin (endoplasmic reticulum (ER) marker) in GIST cells.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
D ICC analysis of KIT, GM130 (cis-Golgi), mannosidase ll (medial-Golgi), and Golgin-97 (trans-Golgi) in GIST cells.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
E Lysates from GIST and CC cells were deglycosylated using endoglycosidase H (Endo-H) or PNGase-F, and analyzed by western blotting.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
F Biotinylation, streptavidin pull-down, and western blotting were performed using GIST and CC cells.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Because the surface expression of MT-KIT was low, twice the amount of biotin-labeled lysates was used for GIST cells than in CC cell lysates.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
G Quantification of the band intensities for the western blots as shown in F. H Stem cell factor (SCF)-treatment-mediated KIT degradation was measured by western blot lysates in GIST and CC cells.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Band intensities of the western blots were quantified.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
One-way ANOVA with a post-hoc test was performed to compare multiple means (*p < 0.05, **p < 0.01, ***p < 0.001).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Error bars in G and H represent the standard deviation (SD) of the mean of three independent western blots.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Although ICC analysis showed Golgi localization of MT-KIT, membranous MT-KIT expression in GISTs and CCs was quantitatively measured by biotin labeling and western blot analysis of PM proteins.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Since the membranous MT-KIT expression in GIST cells was too low, the amount of GIST whole-cell lysate used for biotin-labeled protein pulldown was doubled than that in CCs.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The ratios between membranous KIT levels compared with whole-cell lysates were approximately 0.40 and 0.20 for GIST430 and GIST882 cells, respectively, while those for CC cells were approximately 1.0 (Fig. 1F, G).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The surface expression of MT-KIT in GIST430 cells was higher than in GIST882 cells due to the heterozygous mutation in GIST430 cells .
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Despite a small fraction of the total MT-KIT, weak membranous KIT expression was detected in GIST cells (Fig. 1F).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Therefore, a ligand tolerance assay was performed to test if the membranous MT-KIT responds to its ligand, the stem cell factor (SCF).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
As previously reported , SCF treatment rapidly downregulated WT-KIT expression in CC cells.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
However, MT-KIT levels barely changed in GIST cells following SCF treatment (Fig. 1H).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The fate of membranous MT-KIT was tracked in a time-dependent manner to understand its role in GIST tumorigenesis.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
GIST882 cells harboring the homozygous KIT mutation were used for analysis.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
GIST882 cells were labeled with a fluorescent-dye-conjugated KIT antibody and examined over time using a confocal microscope.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Membranous MT-KIT was internalized within 15 min and disappeared within 1 h. Colocalization was not observed between MT-KIT and a Golgi complex marker, GM130, until MT-KIT disappeared, which excludes the possibility that Golgi retention of MT-KIT is mediated by the endosome-to-trans-Golgi retrieval pathway, a reported Golgi retention mechanism of the G-protein-coupled receptor (Supplementary Fig. S3A).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Next, the involvement of PM quality-control (PMQC) in the disappearance of MT-KIT was investigated.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The labeling experiment was repeated to evaluate the colocalization of MT-KIT with an early endosome marker, EEA1, or a lysosomal marker, LAMP1, involved in the PMQC processes .
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Colocalization of membranous MT-KIT with EEA1 and LAMP1 was clearly observed 15 and 30 min after tracking, and disappeared after 1 h (Supplementary Fig. S3B, C).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
To quantitatively validate the ICC results, western blot analysis of membranous KIT was performed in GISTs and CCs.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
In GISTs, the remaining membranous MT-KIT levels was measured through biotin-labeled protein pulldown assay and western blot at the indicated time-points.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Bafilomycin A1 (BafA1), a lysosomal inhibitor, was used to validate lysosome-mediated protein degradation.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
CCs were included as controls to determine the original stability of WT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Since WT-KIT is mostly expressed in the PM, the remaining WT-KIT abundance was measured at the indicated time-points after cycloheximide (CHX) treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
After 4 h, >50% of the original WT-KIT level remained (Supplementary Fig. S4A), whereas in GIST882 cells, 8% remained.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
MT-KIT degradation was efficiently blocked by BafA1 treatment (Supplementary Fig. S4B).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
These findings suggest that membranous MT-KIT is hardly involved in GIST tumorigenesis due to its low membranous protein level caused by Golgi retention and plasma membrane quality control (PMQC).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Because of low protein levels and rapid degradation of membranous MT-KIT, we hypothesized that the Golgi-localized MT-KIT is the primary contributor to sustained activation of downstream signaling in GISTs.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
We first aimed to exclude the possibility that ER- or PM-localized MT-KIT initiates downstream signaling.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Brefeldin A (BFA) was used to block ER-to-Golgi trafficking, thereby inducing ER retention of MT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
ICC analysis showed that BFA led to ER retention of MT-KIT (Supplementary Fig. S5).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Western blot analysis showed that BFA dramatically reduced phospho-KIT, phospho-AKT, and phospho-ERK levels, indicating that ER-retained MT-KIT was insufficient to activate downstream signaling (Fig. 2A).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
On the other hand, the levels of phospho-AKT and phospho-ERK were minimally affected by BFA treatment in CC cells, whereas KIT was retained in the ER (Supplementary Fig. S6A).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The involvement of membranous MT-KIT in downstream signaling was also investigated using 30N12, an inhibitor of trans-Golgi-to-PM trafficking .
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
To validate the effects of 30N12, western blot and ICC analysis of WT-KIT was performed in SCF-treated CC cells treated with or without 30N12.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Treatment with 30N12 efficiently induced WT-KIT retention in the Golgi complex, and reduced phospho-KIT, phospho-AKT, and phospho-ERK levels, that were upregulated by SCF treatment (Supplementary Fig. S6B, C).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
However, in GIST cells, 30N12 treatment did not change the phosphorylation levels of effector molecules, indicating that PM-localized MT-KIT was also insufficient to activate downstream signaling (Fig. 2B).Fig.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
2Golgi complex is the main site where MT-KIT initiates downstream oncogenic signaling.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
A The status of downstream effector molecules in the KIT signaling pathway was analyzed by western blotting GIST cells with or without treatment with Brefeldin A (BFA, 5 µg/mL) for 4 h, a compound that blocks ER to Golgi trafficking.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
B The same analysis was performed as in A using GIST cells with or without treatment for 18 h with 1 or 10 µM 30N12, a compound that blocks trans-Golgi trafficking to the plasma membrane (PM).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
C Immunoprecipitation of GIST430 and GIST882 cell lysates was performed to evaluate the interaction of MT-KIT with P85 and GRB2, the most upstream molecules of the PI3K/AKT pathway and MAPK/ERK pathway, respectively.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
D, E Confocal microscopic analysis of KIT, GRB2, P85, and GM130 in GIST cells transfected with HA-GRB2 or HA-P85 expression vectors was performed.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
HA-GRB2 and HA-P85 were labeled with hemagglutinin (HA).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
A The status of downstream effector molecules in the KIT signaling pathway was analyzed by western blotting GIST cells with or without treatment with Brefeldin A (BFA, 5 µg/mL) for 4 h, a compound that blocks ER to Golgi trafficking.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
B The same analysis was performed as in A using GIST cells with or without treatment for 18 h with 1 or 10 µM 30N12, a compound that blocks trans-Golgi trafficking to the plasma membrane (PM).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
C Immunoprecipitation of GIST430 and GIST882 cell lysates was performed to evaluate the interaction of MT-KIT with P85 and GRB2, the most upstream molecules of the PI3K/AKT pathway and MAPK/ERK pathway, respectively.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
D, E Confocal microscopic analysis of KIT, GRB2, P85, and GM130 in GIST cells transfected with HA-GRB2 or HA-P85 expression vectors was performed.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
HA-GRB2 and HA-P85 were labeled with hemagglutinin (HA).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
To investigate whether Golgi-retained MT-KIT primarily contributes to downstream oncogenic signaling activation, we investigated the interaction of MT-KIT with P85 and GRB2, the upstream effectors of the PI3K/AKT and MAPK/ERK pathways, respectively.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Immunoprecipitation assays were performed using GIST cell lysates incubated with IgG (control) or KIT antibody.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
This analysis showed that the endogenous MT-KIT bound to both P85 and GRB2 (Fig. 2C).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The interaction of MT-KIT with GRB2 and P85 was further verified through ICC analysis.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Since there are no commercial antibodies for ICC analysis of P85 and GRB2, HA-tagged P85 and GRB2 expression vectors were constructed.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
After vector transfection into GIST cells, cellular localization of MT-KIT, HA-P85, and HA-GRB2 were examined.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
GRB2 and P85 clearly showed colocalization with MT-KIT and GM130 (Fig. 2D, E).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Quantification of immunofluorescence intensity further demonstrated that GRB2 and P85 colocalize with MT-KIT and GM130 at the Golgi complex (Supplementary Fig. S7).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The localization of GRB2 and P85 after SCF treatment in CC cells was further investigated to compare the PI3K/AKT and MAPK/ERK pathway activation mediated by WT-KIT and MT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
In contrast to GIST cells, ICC analysis showed that SCF treatment recruited P85 and GRB2 to the peri-PM region, where activated WT-KIT was localized (Supplementary Fig. S8).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
These data showed that MT-KIT directly initiates downstream signals from the Golgi complex, whereas WT-KIT initiates signals from the PM.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Since the Golgi complex is a hub for constant protein trafficking, a complementary mechanism is necessary for the retention of MT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Therefore, we aimed to identify a possible MT-KIT-binding partner from the Golgi-related proteins that could tether MT-KIT to the Golgi complex during trafficking.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Since there are only a few reported Golgi-related proteins [13–15], all possible candidates with commercially available antibodies were selected.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Western blot was performed on ten Golgi proteins (GBF1, GM130, Golgin97, TGN38, GRASP65, GRASP55, BLZF1, STX3, STX6, and GOLPH3) in small-cell lung cancer (SCLC), leukemia, colon cancer, and GIST cell lines expressing WT-KIT or MT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
All Golgi proteins showed variable levels in the cell lines, except for BLZF1 that selectively showed high protein levels in GIST 430 and GIST 882 cells (Fig. 3A).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
BLZF1 expression was also similarly high in imatinib-resistant GIST430-V654A and GIST48 cells (Supplementary Fig. S9).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Moreover, immunoprecipitation with KIT antibody revealed that MT-KIT specifically bound to BLZF1 (Fig. 3B).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
The colocalization of MT-KIT and BLZF1 in the Golgi complex of GIST cells was validated by ICC analysis (Fig. 3C, D).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
On the other hand, fluorescence signal of BLZF was barely detected in the Golgi complex of CC and leukemia cell lines (DLD-1 and HMC-1) (Supplementary Fig. S10).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
BLZF1 knockdown with short hairpin RNA (shRNA) dramatically downregulated MT-KIT expression, as demonstrated by ICC and western blot analyses (Fig. 3C–E).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
BLZF1 knockdown strongly inhibited cell growth in both imatinib-sensitive GIST430 and GIST 882 cells, and in imatinib-resistant GIST430-V654A and GIST48 cells (Fig. 3F and Supplementary Fig. S11).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
These findings collectively suggest that BLZF1 is required for Golgi retention and stable expression of MT-KIT, and consequently for GIST cell growth.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Fig. 3BLZF1 is a novel KIT binding partner, which is indispensable for tethering MT-KIT in the Golgi complex.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
A Western botting was performed using antibodies against ten Golgi-related proteins in small cell lung carcinoma (SCLC), leukemia, CC, and GIST cell lines expressing WT-KIT or MT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
B Immunoprecipitation analysis was performed in GIST cells using a KIT antibody and binding between KIT and Golgi-related proteins was evaluated by western blotting.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
C, D Confocal microscopic analysis of GM130, BLZF1, and KIT in GIST cells with or without BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
E Western blotting analysis of KIT and BLZF1 in GIST cells with or without BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
F A proliferation assay was performed in GIST cells with or without BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Cell growth was measured by MTT analysis 72 h after BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Error bars in F represents the SD of the mean of three independent experiments.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
One-way ANOVA with a post-hoc test was performed to compare multiple means (*p < 0.05, **p < 0.01, ***p < 0.001).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
A Western botting was performed using antibodies against ten Golgi-related proteins in small cell lung carcinoma (SCLC), leukemia, CC, and GIST cell lines expressing WT-KIT or MT-KIT.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
B Immunoprecipitation analysis was performed in GIST cells using a KIT antibody and binding between KIT and Golgi-related proteins was evaluated by western blotting.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
C, D Confocal microscopic analysis of GM130, BLZF1, and KIT in GIST cells with or without BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
E Western blotting analysis of KIT and BLZF1 in GIST cells with or without BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
F A proliferation assay was performed in GIST cells with or without BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Cell growth was measured by MTT analysis 72 h after BLZF1 shRNA treatment.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Error bars in F represents the SD of the mean of three independent experiments.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
One-way ANOVA with a post-hoc test was performed to compare multiple means (*p < 0.05, **p < 0.01, ***p < 0.001).
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
It remains unclear how MT-KIT bypasses ERQC to reach the Golgi complex.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
As shown in Fig. 1E, MT-KIT in GISTs was primarily in the post-ER form, which indicates that MT-KIT is folded enough to avoid ER accumulation and stress induction.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Since GIST cells are constantly exposed to nutrient deficiency and hypoxia that cause ER stress.
PMC10589262
Identification of novel pathogenic roles of BLZF1/ATF6 in tumorigenesis of gastrointestinal stromal tumor showing Golgi-localized mutant KIT
Therefore, we hypothesized that GISTs might have acquired a UPR-related intrinsic mechanism to relieve ER stress during tumorigenesis.