C-KIT two mutation sites in patients with imatinib mesylate secondary resistance
All specimens were analyzed by RT-PCR amplification, DNA sequencing and analysis and then comparison with wild type c-KIT gene, C-KIT/PDGFR-α mutation were detection, secondary mutation were found in 3 GIST specimens with drug resistance. one case locus in the v654a of exon 13, one case locus in the T760I of exon 14, the other locus in the v654a of exon 17(Figure 1), which confirm the resistance of imatinib mesylate and offer a potential theoretical basic of the application probability of circRNAs.
Identification And Characteristics Of Circrnas
To explore circRNA expression profiles in N, Y or YC, and C group, we performed ribosomal RNA-depleted RNA sequencing and the number of circRNAs identified in each sample is shown in Figure 2A. Venn analysis showed that 11935 circRNAs were found between predicted circRNAs and circBase (Figure 2B). According to the circular RNAs array, a total of 30,550 were detected in 9 samples, and the length mostly distribute in 201-400bp and >2000bp (Figure 2C). Chr1, Chr2 and Chr3 are the three most located chromosomes (Figure 2D). Most circular RNAs have less than 6 exons (Figure 2E). Similarly, most of the identified circular RNAs (27050, 88.54%) came from the overlapping regions of meaning, indicating that the formation of circular RNAs is closely related to the pre-mRNA splicing mechanism (Figure 1F). Approximately 3.82% (1167) and 5.41% (1652) circular RNAs were derived from exons and intergenic regions. A small part of circular RNA is antisense circular RNA (383, 1.25%) and intronic circRNAs (298, 0.98%). General features of the circRNA sequencing data were list in Table 1.
Table 1
General features of the circRNA sequencing data
Sample
|
raw reads
|
raw bases
|
clean reads
|
clean bases
|
valid bases
|
Q30
|
GC
|
Sample_N1
Sample_N2
Sample_N3
Sample_C1
Sample_C2
Sample_C3
Sample_YC_1
Sample_YC_2
Sample_YC_3
|
84587074
91507150
91320298
84193988
82799646
85145886
84743526
83362440
82891684
|
10573384250
11438393750
11415037250
10524248500
10349955750
10643235750
10592940750
10420305000
10361460500
|
81651670
88469786
88647372
81676720
80243548
82621864
81602896
80906514
80622518
|
10201851969
11053620694
11076539842
10204694315
10025345565
10322885971
10186655571
10108276460
10073190258
|
96.48%
96.63%
97.03%
96.96%
96.86%
96.99%
96.16%
97.00%
97.21%
|
93.56%
93.73%
94.29%
94.20%
93.93%
94.11%
93.57%
94.37%
94.35%
|
55.50%
56.00%
57.00%
58.00%
58.00%
55.50%
57.00%
50.50%
55.50%
|
The Potential Functions Identification
Recent study has reported that circRNAs possess has tissue-specific expression characteristics. we used DEseq software to analyze circRNA expression profiles RPM to screen dysregulated circRNAs in three different GIST samples, found that that no abnormal expression was observed in three different GIST samples (Figure 3A). PCA (Principal Component Analysis) was performed to analyze the circRNA expression profiles of the three groups samples. The distance between points represented the similarity between the two samples, and the repeatability of the three groups of samples was ideal in Figure 3B. Differential analysis was conducted among the three comparison groups by Volcano plots. The circRNA differentially expressed was screened using the criteria of "adjusted pvalue < 0.05 and absolute value of log2Foldchange >1". The red dot on the volcano map was significantly increased circRNA, the green dot was significantly reduced circRNA, and the gray dot showed no obvious difference (Figure 3C).These were 159, 98, and 37 circRNAs up-regulated, 277, 284, and 23 circRNAs down-regulated in comparison C-vs-N, YC-vs-N and C-vs-YC, respectively(Figure 3D). Venn analysis of the three comparison groups was shown in Figure 3E. In general, the same kind of samples can be clustered in the same cluster, and the genes in the same cluster may have similar biological functions, our results show that all samples in paired groups have the co-regulated (up or down) genes (Figure 3F). The top ten different expression circRNA in the three comparison groups was shown in Table 2.
Table 2
Top 10 differentially expressed circRNAs in the three comparison groups
circRNA_id
|
circBase_id
|
log2FoldChange
|
P-value
|
Adjusted P-value
|
Regulation
|
Host genes
|
C-vs-N
|
|
|
|
|
|
|
circRNA_09533
|
hsa_circ_0006867
|
-8.62
|
9.25E-90
|
2.61E-85
|
Down
|
LRBA
|
circRNA_17427
|
hsa_circ_0018064
|
-inf
|
3.05E-64
|
4.30E-60
|
Down
|
SVIL
|
circRNA_20776
|
hsa_circ_0026782
|
-9.86
|
7.21E-53
|
6.78E-49
|
Down
|
ITGA7
|
circRNA_09530
|
-
|
-inf
|
2.72E-46
|
1.92E-42
|
Down
|
LRBA
|
circRNA_13055
|
hsa_circ_0079284
|
-5.41
|
2.84E-43
|
1.60E-39
|
Down
|
RNF216
|
circRNA_11884
|
hsa_circ_0004119
|
-5.40
|
1.63E-41
|
7.69E-38
|
Down
|
RAB23
|
circRNA_01991
|
hsa_circ_0005230
|
5.26
|
1.57E-35
|
6.32E-32
|
Up
|
DNM3
|
circRNA_13811
|
hsa_circ_0004365
|
-inf
|
7.44E-35
|
2.62E-31
|
Down
|
SEMA3C
|
circRNA_03576
|
hsa_circ_0000994
|
-4.03
|
2.99E-30
|
8.43E-27
|
Down
|
SLC8A1
|
circRNA_26953
|
hsa_circ_0000825
|
-5.70
|
2.70E-30
|
8.43E-27
|
Down
|
MTCL1
|
C-vs-YC
|
|
|
|
|
|
|
circRNA_01991
|
hsa_circ_0005230
|
3.92
|
1.33E-19
|
2.49E-15
|
Up
|
DNM3
|
circRNA_03862
|
hsa_circ_0004435
|
-2.74
|
1.07E-12
|
6.67E-09
|
Down
|
FANCL
|
circRNA_15734
|
-
|
Inf
|
9.93E-13
|
6.67E-09
|
Up
|
-
|
circRNA_11269
|
hsa_circ_0003718
|
-4.00
|
6.83E-12
|
3.20E-08
|
Down
|
RANBP17
|
circRNA_02957
|
hsa_circ_0002922
|
-2.17
|
2.05E-11
|
7.68E-08
|
Down
|
ZNF124
|
circRNA_30179
|
-
|
-inf
|
3.18E-11
|
9.95E-08
|
Down
|
DIAPH2
|
circRNA_30540
|
hsa_circ_0009024
|
-inf
|
7.27E-11
|
1.95E-07
|
Down
|
-
|
circRNA_03489
|
hsa_circ_0000992
|
3.91
|
4.07E-10
|
9.55E-07
|
Up
|
PRKD3
|
circRNA_04497
|
-
|
-2.60
|
5.75E-10
|
1.20E-06
|
Down
|
DPP10
|
circRNA_25651
|
-
|
Inf
|
9.34E-10
|
1.75E-06
|
Up
|
ZC3H18
|
YC-vs-N
|
|
|
|
|
|
|
circRNA_09533
|
hsa_circ_0006867
|
-8.15
|
1.75E-86
|
4.41E-82
|
Down
|
LRBA
|
circRNA_17427
|
hsa_circ_0018064
|
-inf
|
1.81E-67
|
2.28E-63
|
Down
|
SVIL
|
circRNA_13055
|
hsa_circ_0079284
|
-7.80
|
8.02E-60
|
6.75E-56
|
Down
|
RNF216
|
circRNA_04497
|
-
|
Inf
|
5.19E-58
|
3.27E-54
|
Up
|
DPP10
|
circRNA_09530
|
-
|
-inf
|
4.50E-47
|
2.27E-43
|
Down
|
LRBA
|
circRNA_11884
|
hsa_circ_0004119
|
-4.77
|
1.01E-39
|
4.26E-36
|
Down
|
RAB23
|
circRNA_20776
|
hsa_circ_0026782
|
-6.94
|
1.03E-33
|
3.70E-30
|
Down
|
ITGA7
|
circRNA_26999
|
hsa_circ_0008821
|
-inf
|
5.42E-32
|
1.71E-28
|
Down
|
RAB31
|
circRNA_13811
|
hsa_circ_0004365
|
-6.68
|
1.69E-29
|
4.74E-26
|
Down
|
SEMA3C
|
circRNA_18913
|
hsa_circ_0000277
|
6.50
|
1.12E-27
|
2.82E-24
|
Up
|
PDE3B
|
GO enrichment analysis for the host genes of differentially expressed circRNAs
After get the differentially expressed genes, we selected the top10 functional enrichment analysis. The enriched functional terms were used as the predicted functional term of given circRNAs. Analysis the difference gene expression with GO analysis, to describe its function (with GO annotation). GO analyses covered three subgroups: biological process (BP), cellular component (CC), and Molecular function (MF). The GO analysis with the most significant enrichment in the BP, CC, and MF subgroups by C-vs-N comparison groups is regulation of transcription, DNA-templated, cytosol and metal ion binding, respectively. In C-vs-YC group, the GO analysis with the most significant enrichment in the BP, CC, and MF subgroups is regulation of transcription, DNA-templated, nucleoplasm and double-stranded DNA binding. In YC-vs-N group, the GO analysis with the most significant enrichment in the BP, CC, and MF subgroups is regulation of transcription from RNA polymerase II promoter, cytosol and metal ion binding (Figure 4A-C).
Construction Of The Circrna-mirna Interaction Network In Drug Resistance/hif-1
We combined the chip data (OE2016Q1031Y) from another of our published articles to draw the cirRNA-miRNA-mRNA network in the group C vs YC, and found that, 15 cirRNA were up-regulated (Red), 8 cirRNA was down-regulated (Green) (Figure 5A). GO enrichment analysis of the cirRNA-miRNA-mRNA network, the bubble diagram shows the top 20 enriched GO terms (P<0.05) (Figure 5B). KEGG pathway enrichment analysis of the cirRNA-miRNA-mRNA network, and found out potential relationship between differential expression genes with changes of cell pathways, such as HIF-1 pathway, Central carbon metabolism in cancer, AMPK signaling pathway, Autophagy-animal and so on (Figure 5C). Later, we analyzed the cirRNA-miRNA-mRNA network involved in the HIF-1 pathway, found that the correlation between each dysregulated circRNA-miRNAs-mRNA, circRNA_06551, circRNA_14668, circRNA_04497, circRNA_08683, circRNA_09923(Green, down-regulation) and circRNA_23636, circRNA_15734(Red, up-regulation) (Figure 5D).