PAQR3 expression was elevated in human breast cancer
We compared the PAQR3 expression between breast cancer and paired normal tissues. A decrease in ER and/or PR positive (ER/PR+) tumor tissues was found compared with the paired normal tissues (P < 0.0500), whereas no such difference was identified in ER and PR negative (ER/PR-) breast cancer (P > 0.0500) (Fig. 1A). With an online dataset (http://co.bmc.lu.se/gobo) [17], we found PAQR3 expression was negatively associated with ER expression (P < 0.0001), whereas positively associated with tumor grade (P < 0.0001) (Fig. 1B).
Paqr3 Expression Was Associated With Breast Cancer Clinicopathological Features
The associations between PAQR3 expression and clinicopathological features were further explored in 1,873 cases of breast cancer (Cohort A). The demographics and baseline clinicopathological characteristics were listed (Table 1). Tumors with higher levels of PAQR3 were more likely to occur in the patients aged less than 70 years (P < 0.0001) and those at the period of premenopause (P < 0.0001). In addition, PAQR3 expression was associated with the higher tumor grade (III vs. I + II, P < 0.0001), lymphatic invasion (P = 0.0170), ER loss (P < 0.0001) and PR loss (P < 0.0001) (Table 2 and Fig. 2).
Table 1
Description of the training cohort characteristics (N = 1873)
|
Training Set
(n = 936)
|
Validation Set
(n = 937)
|
Whole Series
(n = 1,873)
|
Age at diagnosis (years)
< 35
35–70
> 70
|
19 (2.0)
655 (70.0)
262 (28.0)
|
23 (2.4)
675 (72.0)
239 (25.6)
|
42 (2.2)
1330 (71.0)
501 (26.8)
|
Menopausal status
Pre
Post
|
199 (21.2)
737 (78.8)
|
214 (22.8)
723 (77.2)
|
413 (22.0)
1460 (78.0)
|
Tumor grade
I
II
III
|
78 (8.3)
384 (41.0)
474 (50.7)
|
79 (8.4)
387 (41.3)
471 (50.3)
|
157 (8.3)
771 (41.2)
945 (50.5)
|
Tumor stage
T1
T2
T3
|
429 (45.8)
468 (50.0)
39 (4.2)
|
404 (43.1)
474 (50.6)
59 (6.3)
|
833 (44.5)
942 (50.3)
98 (5.2)
|
Lymph node status
Negative
Positive
|
484 (51.7)
452 (48.3)
|
482 (51.4)
455 (48.6)
|
966 (51.6)
907 (48.4)
|
ER
Negative
Positive
|
219 (23.4)
717 (76.6)
|
230 (24.5)
707 (75.5)
|
449 (24.0)
1424 (76.0)
|
PR
Negative
Positive
|
463 (49.5)
473 (50.5)
|
435 (46.4)
502 (53.6)
|
898 (48.0)
975 (52.0)
|
HER2
Negative
Positive
|
815 (87.1)
121 (12.9)
|
822 (87.8)
115 (12.2)
|
1637 (87.4)
236 (12.6)
|
Chemotherapy
Yes
No
|
201 (21.5)
735 (78.5)
|
202 (21.6)
735 (78.4)
|
403 (21.5)
1470 (78.5)
|
Radiotherapy
Yes
No
|
564 (60.2)
372 (39.8)
|
571 (60.9)
366 (39.1)
|
1135 (60.6)
738 (39.4)
|
Hormone therapy
Yes
No
|
582 (62.2)
354 (37.8)
|
579 (61.8)
358 (38.2)
|
1161 (62.0)
712 (38.0)
|
Table 2
Comparison of the clinicopathological parameters between low and high PAQR3 expression in training cohort of breast cancer patients (N = 1,873)
|
Low PAQR3
(N = 903)
|
High PAQR3
(N = 970)
|
P value
(χ2 test)
|
Age at diagnosis (years)
|
|
|
< 0.0001
|
< 35
|
12 (1.3%)
|
30 (3.1%)
|
|
35–70
|
579 (64.1%)
|
751 (77.4%)
|
|
> 70
|
312 (34.6%)
|
189 (19.5%)
|
|
Menopausal status
|
|
|
< 0.0001
|
Pre
|
164 (18.2%)
|
249 (25.7%)
|
|
Post
|
739 (81.8%)
|
721 (74.3%)
|
|
Tumor stage
|
|
|
0.8450
|
T1
|
399 (44.2%)
|
434 (44.7%)
|
|
T2 + T3
|
504 (55.8%)
|
536 (55.3%)
|
|
Tumor grade
|
|
|
< 0.0001
|
I + II
|
535 (59.2%)
|
393 (40.5%)
|
|
III
|
368 (40.8%)
|
577 (59.5%)
|
|
Lymph node status
|
|
|
0.0170
|
Negative
|
492 (54.5%)
|
474 (48.9%)
|
|
Positive
|
411 (45.5%)
|
496 (51.1%)
|
|
ER status
|
|
|
< 0.0001
|
Negative
|
113 (12.5%)
|
336 (34.6%)
|
|
Positive
|
790 (87.5%)
|
634 (65.4%)
|
|
PR status
|
|
|
< 0.0001
|
Negative
|
321 (35.5%)
|
577 (59.5%)
|
|
Positive
|
582 (64.5%)
|
393 (40.5%)
|
|
HER2 status
|
|
|
0.0640
|
Negative
|
803 (88.9%)
|
834 (86.0%)
|
|
Positive
|
100 (11.1%)
|
136 (14.0%)
|
|
Another cohort of 479 breast cancer patients were applied to validate the above findings (Cohort B). The age and baseline characteristics were described (Table S1). Similarly, PAQR3 was associated with the higher tumor grade (P = 0.0080), ER loss (P < 0.0001) and PR loss (P = 0.0020) (Table 3).
Table 3
Comparison of the clinicopathological parameters between low and high PAQR3 expression in validation cohort of breast cancer patients (N = 479)
|
Low PAQR3
(N = 276)
|
High PAQR3
(N = 203)
|
P value
(χ2 test)
|
Age at diagnosis
|
|
|
0.0660
|
< 35
|
19 ( 6.9%)
|
19 ( 9.4%)
|
|
35–70
|
245 (88.8%)
|
182 (89.7%)
|
|
> 70
|
12 ( 4.3%)
|
2 ( 1.0%)
|
|
Tumor stage
|
|
|
0.7280
|
T1
|
17 ( 6.2%)
|
15 ( 7.4%)
|
|
T2 + T3
|
259 (93.8%)
|
188 (92.6%)
|
|
Lymph node status
|
|
|
0.1960
|
Negative
|
94 (34.1%)
|
57 (28.1%)
|
|
Positive
|
182 (65.9%)
|
146 (71.9%)
|
|
Tumor grade
|
|
|
0.0080
|
I + II
|
134 (48.6%)
|
73 (36.0%)
|
|
III
|
142 (51.4%)
|
130 (64.0%)
|
|
AJCC.stage
|
|
|
0.4840
|
1
|
4 ( 1.4%)
|
4 ( 2.0%)
|
|
2
|
159 (57.6%)
|
106 (52.2%)
|
|
3
|
113 (40.9%)
|
93 (45.8%)
|
|
ER status
|
|
|
< 0.0001
|
Negative
|
92 (33.3%)
|
113 (55.7%)
|
|
Positive
|
184 (66.7%)
|
90 (44.3%)
|
|
PR status
|
|
|
0.0020
|
Negative
|
125 (45.3%)
|
122 (60.1%)
|
|
Positive
|
151 (54.7%)
|
81 (39.9%)
|
|
HER2 status
|
|
|
0.4360
|
Negative
|
258 (93.5%)
|
194 (95.6%)
|
|
Positive
|
18 ( 6.5%)
|
9 ( 4.4%)
|
|
Paqr3 Independently Predicted The Outcomes For Breast Cancer Patients
Patients with the higher levels of PAQR3 had a shorter overall survival (OS) (P = 0.0306) and recurrence free survival (RFS) (P < 0.0001), as compared to the patients with lower PAQR3 expression (Fig. 3).
Univariate survival analysis showed that higher PAQR3 expression, younger age, premenopause, higher tumor grade, lymphatic invasion, ER loss, PR loss, and HER2 overexpression predicted an increased risk of death. When multivariate survival analysis using Cox regression was performed, higher PAQR3 expression remained as the significant predictor for increased risk of death (HR = 1.20, 95%CI = 1.06–1.37, P = 0.0055). Other significant predictors included younger age, premenopause, higher tumor grade, lymphatic invasion and HER2 overexpression (Table 4).
Table 4
Univariate and multivariate analysis of predictive factors for survival in patients with breast cancer
Variable
|
Overall survival
|
Recurrence free survival
|
Univariate Analysis
|
HR
|
95% CI
|
P value
|
HR
|
95% CI
|
P value
|
PAQR3
(high/low)
|
1.14
|
1.01–1.29
|
0.0310
|
1.44
|
1.23–1.69
|
< 0.0001
|
Age at diagnosis (< 35/>70/35–70)
|
2.08
|
1.84–2.36
|
< 0.0001
|
--
|
--
|
NS
|
Menopausal status
(Post/Pre)
|
1.68
|
1.42–1.98
|
< 0.0001
|
--
|
--
|
NS
|
Tumor stage
(T2 + T3/T1)
|
--
|
--
|
NS
|
--
|
--
|
NS
|
Tumor grade
(III/I + II)
|
1.34
|
1.18–1.51
|
< 0.0001
|
1.83
|
1.56–2.15
|
< 0.0001
|
Lymph node status
(Positive/Negative)
|
1.70
|
1.50–1.91
|
< 0.0001
|
2.28
|
1.94–2.68
|
< 0.0001
|
ER status
(Positive/Negative)
|
0.84
|
0.73–0.96
|
0.0130
|
0.59
|
0.50–0.70
|
< 0.0001
|
PR status
(Positive/Negative)
|
0.76
|
0.68–0.86
|
< 0.0001
|
0.61
|
0.52–0.72
|
< 0.0001
|
HER2 status
(Positive/Negative)
|
1.49
|
1.26–1.78
|
< 0.0001
|
2.05
|
1.68–2.51
|
< 0.0001
|
Chemotherapy
(Yes/No)
|
1.28
|
1.1–1.48
|
0.0010
|
2.17
|
1.83–2.58
|
< 0.0001
|
Radiotherapy
(Yes/No)
|
0.85
|
0.75–0.95
|
0.0070
|
--
|
--
|
NS
|
Hormone therapy
(Yes/No)
|
1.25
|
1.10–1.42
|
0.0010
|
--
|
--
|
NS
|
Multivariable Analysis
|
HR
|
95%CI
|
P value
|
HR
|
95%CI
|
P value
|
PAQR3
(low/high)
|
1.20
|
1.06–1.37
|
0.0055
|
1.28
|
1.04–1.45
|
0.0170
|
Age at diagnosis (< 35/35–70/>70)
|
2.14
|
1.86–2.46
|
< 0.0001
|
--
|
--
|
NS
|
Menopausal status
(Pre/Post)
|
1.47
|
1.23–1.78
|
< 0.0001
|
--
|
--
|
NS
|
Tumor grade
(I + II/III)
|
1.25
|
1.10–1.43
|
0.0010
|
1.41
|
1.18–1.68
|
0.0002
|
Lymph node status
(Negative/Positive)
|
1.61
|
1.39–1.86
|
< 0.0001
|
1.98
|
1.65–2.38
|
< 0.0001
|
HER2 status
(Negative/Positive)
|
1.37
|
1.14–1.65
|
0.0008
|
1.62
|
1.31–2.01
|
< 0.0001
|
Chemotherapy
(Yes/No)
|
1.28
|
1.04–1.58
|
0.0194
|
--
|
--
|
NS
|
Radiotherapy
(Yes/No)
|
0.77
|
0.68–0.88
|
< 0.0001
|
--
|
--
|
NS
|
NS, none significance. |
Univariate survival analysis showed that higher PAQR3 expression, higher tumor grade, lymphatic invasion, ER loss, PR loss, and HER2 overexpression predicted an increased risk of tumor recurrence. When multivariate survival analysis using Cox regression was applied, higher PAQR3 expression remained as the significant predictor for shorter RFS (HR = 1.28, 95%CI = 1.04–1.45, P = 0.0170). Other significant predictors included higher tumor grade, lymphatic invasion and HER2 overexpression (Table 4).
To verify the predictive role of PAQR3 expression for breast cancer patients’ outcomes, we randomly divided 1,873 patients into the training (N = 936) and validation (N = 937) sets. The demographics and baseline clinicopathological characteristics were summarized (Table 1). After adjustment for other predictors including younger age, premenopause, higher tumor grade, lymphatic invasion and HER2 overexpression, the higher PAQR3 expression remained serving as an independent predictor for shorter OS in the training set (HR = 1.24, P = 0.0206), and was likely to predict the OS in the validation set (HR = 1.18, P = 0.0884) (Table S2). However, we did not find that the higher PAQR3 expression predicted shorter RFS in training and validation sets.
Paqr3 Better Predicted The Outcomes In Er/pr + breast Cancer
As ER/PR status was associated with PAQR3 expression, we stratified the 1,873 patients according to the ER and PR status, and then studied if PAQR3 expression predicted the outcomes in ER + and PR + breast cancer, respectively.
In ER + breast cancer, multivariate survival analysis using Cox regression showed that PAQR3 independently predicted shorter OS (HR = 1.28, 95%CI = 1.11–1.48, P = 0.0006) and RFS (HR = 1.46, 95%CI = 1.19–1.77, P = 0.0002) (Table 5 and Fig. 4). Nevertheless, no such a predictive role of PAQR3 expression was found in ER- breast cancer.
Table 5
Multivariate analysis of predictive factors for survival in patients with ER/PR positive breast cancer
Variable
|
Overall survival
|
Recurrence free survival
|
ER positive group
|
PR positive group
|
ER positive group
|
PR positive group
|
Multivariable Analysis
|
HR
|
P value
|
HR
|
P value
|
HR
|
P value
|
HR
|
P value
|
PAQR3
(high/low)
|
1.28
|
0.0006
|
1.30
|
0.0037
|
1.46
|
0.0002
|
1.48
|
0.0016
|
Age at diagnosis (< 35/35–70/>70)
|
2.21
|
< 0.0001
|
2.44
|
< 0.0001
|
1.44
|
0.0010
|
1.72
|
0.0001
|
Menopausal status
(Post/Pre)
|
1.75
|
< 0.0001
|
1.79
|
0.0001
|
--
|
NS
|
--
|
NS
|
Tumor grade
(III/I + II)
|
1.25
|
0.0025
|
1.45
|
0.0001
|
1.49
|
0.0001
|
1.75
|
< 0.0001
|
Lymph node status
(Positive/Negative)
|
1.58
|
< 0.0001
|
1.45
|
0.0004
|
2.09
|
< 0.0001
|
2.02
|
< 0.0001
|
HER2 status
(Positive/Negative)
|
1.46
|
0.0038
|
1.49
|
0.0327
|
1.85
|
0.0001
|
1.86
|
0.0053
|
Chemotherapy (Yes/No)
|
1.40
|
0.0118
|
1.55
|
0.0092
|
1.45
|
0.0145
|
1.62
|
0.0132
|
Radiotherapy
(Yes/No)
|
0.76
|
0.0002
|
0.71
|
0.0001
|
--
|
NS
|
--
|
NS
|
Hormone therapy
(Yes/No)
|
--
|
NS
|
--
|
NS
|
0.772
|
0.0492
|
--
|
NS
|
NS, none significance. |
In PR + breast cancer, PAQR3 also independently predicted shorter OS (HR = 1.30, 95%CI = 1.09–1.56, P = 0.0037) and RFS (HR = 1.48, 95%CI = 1.16–1.89, P = 0.0016), as showed in the multivariate survival analysis using Cox regression (Table 5 and Fig. 4). However, no such a role was found for PAQR3 expression in PR- breast cancer.
Internally validating the predictive role of PAQR3 in ER/PR + breast cancer
We verified the predictive role of PAQR3 expression for breast cancer patients’ outcomes according to the ER and PR status. The previously assigned training (N = 936) and validation (N = 937) sets were utilized here.
In ER + breast cancer, PAQR3 consistently served as an independent predictor for OS (HR = 1.30, P = 0.0109; HR = 1.31, P = 0.0106) and RFS (HR = 1.41, P = 0.0168; HR = 1.52, P = 0.0034) in both of training and validation sets (Table 6).
Table 6
Multivariate analysis of predictive factors for survival in ER/PR positive training/validation cohort of breast cancer
|
Overall survival
|
Recurrence free survival
|
ER positive
|
training cohort
|
validation cohort
|
training cohort
|
validation cohort
|
Multivariable analysis
|
HR
|
P value
|
HR
|
P value
|
HR
|
P value
|
HR
|
P value
|
PAQR3
(high/low)
|
1.30
|
0.0109
|
1.31
|
0.0106
|
1.41
|
0.0168
|
1.52
|
0.0034
|
Age at diagnosis (< 35/35–70/>70)
|
1.99
|
< 0.0001
|
2.38
|
< 0.0001
|
1.37
|
0.0445
|
1.53
|
0.0087
|
Menopausal status
(Post/Pre)
|
1.75
|
0.0014
|
1.69
|
0.0035
|
--
|
NS
|
--
|
NS
|
Tumor grade
(III/I + II)
|
--
|
NS
|
1.39
|
0.0020
|
--
|
NS
|
1.93
|
< 0.0001
|
Lymph node status
(Positive/Negative)
|
1.93
|
< 0.0001
|
1.31
|
0.0235
|
2.32
|
< 0.0001
|
1.88
|
0.0002
|
HER2 status
(Positive/Negative)
|
1.44
|
0.0377
|
1.52
|
0.0360
|
1.84
|
0.0042
|
1.83
|
0.0091
|
Chemotherapy (Yes/No)
|
--
|
NS
|
1.66
|
0.0077
|
--
|
NS
|
1.62
|
0.0283
|
Radiotherapy
(Yes/No)
|
0.78
|
0.0130
|
0.74
|
0.0045
|
--
|
NS
|
--
|
NS
|
|
Overall survival
|
Recurrence free survival
|
PR positive
|
training cohort
|
validation cohort
|
training cohort
|
validation cohort
|
Multivariable analysis
|
HR
|
P value
|
HR
|
P value
|
HR
|
P value
|
HR
|
P value
|
PAQR3
(high/low)
|
1.53
|
0.0013
|
1.18
|
0.2101
|
1.91
|
0.0004
|
1.21
|
0.2716
|
Age at diagnosis (< 35/35–70/>70)
|
2.24
|
< 0.0001
|
2.39
|
< 0.0001
|
1.82
|
0.0028
|
1.65
|
0.0075
|
Menopausal status
(Post/Pre)
|
1.87
|
0.0027
|
1.65
|
0.0124
|
--
|
NS
|
--
|
NS
|
Tumor grade
(III/I + II)
|
1.40
|
0.0105
|
1.56
|
0.0007
|
--
|
NS
|
2.24
|
< 0.0001
|
Lymph node status
(Positive/Negative)
|
1.96
|
< 0.0001
|
--
|
NS
|
2.76
|
< 0.0001
|
--
|
NS
|
HER2 status
(Positive/Negative)
|
--
|
NS
|
2.47
|
0.0005
|
--
|
NS
|
2.69
|
0.0006
|
Chemotherapy (Yes/No)
|
--
|
NS
|
1.71
|
0.0185
|
--
|
NS
|
--
|
NS
|
Radiotherapy
(Yes/No)
|
1.96
|
0.0004
|
0.74
|
0.0176
|
--
|
NS
|
--
|
NS
|
NS, none significance |
Nevertheless, in PR + breast cancer, the prognostic value of PAQR3 expression could not be internally confirmed (Table 6).