H4K20me3, H3K4me2 and H3K9me2 mediate the effect of ER on prognosis in breast cancer

Figures & data

Figure 1. Model of histone methylations mediating the association between ER and breast cancer prognosis.

Table 1. Characteristics at baseline and the associations with prognosis of 1045 breast cancer patients.

		Overall mortality		Disease progression
Characteristics	Total^a (%)	Events	HR (95%CI)	Events		HR (95%CI)
Age at diagnosis	Continuous (Median, IQR) 48 (41–56)
≤40	244 (23.4)	43	1.15 (0.81–1.64)	74		1.44 (1.09–1.90)
41–60	677 (65.0)	110	1.00	158		1.00
≥61	121 (11.6)	28	1.38 (0.91–2.09)	33		1.14 (0.78–1.66)
Menopausal status
Pre-menopausal	585 (59.0)	88	1.00	135		1.00
Post-menopausal	406 (41.0)	84	1.35 (1.00–1.82)	116		1.22 (0.96–1.57)
Educational level
Below junior school	290 (56.0)	41	1.00	64		1.00
Senior high school	113 (21.8)	23	1.24 (0.74–2.06)	35		1.35 (0.89–2.03)
College or above	115 (22.2)	14	0.78 (0.42–1.43)	30		1.14 (0.74–1.76)
Parity
0	38 (3.8)	8	1.00	13		1.00
≥1	964 (96.2)	163	0.73 (0.36–1.48)	241		0.65 (0.37–1.13)
BMI (kg/m^2)
<23	511 (51.8)	96	1.00	137		1.00
23–24.9	229 (23.2)	32	0.74 (0.49–1.10)	52		0.82 (0.59–1.13)
≥25	246 (24.6)	43	0.94 (0.65–1.34)	64		0.94 (0.70–1.27)
Clinical stage
I/II	706 (70.0)	86	1.00	137		1.00
III/IV	303 (30.0)	89	2.99 (2.22–4.02)	118		2.50 (1.95–3.20)
ER status
Negative	263 (26.4)	56	1.00	78		1.00
Positive	733 (73.6)	115	0.67 (0.48–0.92)	175		0.73 (0.56–0.95)
PR status
Negative	271 (27.3)	54	1.00	73		1.00
Positive	723 (72.7)	117	0.72 (0.52–1.00)	179		0.83 (0.63–1.09)
HER2 status
Negative	697 (66.9)	118	1.00	180		1.00
Equivocal	90 (8.6)	20	1.27 (0.79–2.04)	26		1.13 (0.75–1.70)
Positive	255 (24.5)	43	1.05 (0.74–1.49)	59		0.93 (0.69–1.25)
Ki-67
≤14%	232 (29.6)	28	1.00	47		1.00
>14%	553 (70.4)	96	1.48 (0.97–2.26)	148		1.38 (0.99–1.92)
Histological grade
I/II	696 (73.3)	116	1.00	172		1.00
III	253 (26.7)	52	1.37 (0.99–1.91)	67		1.17 (0.88–1.56)
Tumor size (cm)
≤2	299 (29.9)	30	1.00	52		1.00
>2	702 (70.1)	142	2.14 (1.44–3.17)	198		1.72 (1.27–2.34)
Nodal status
Negative	442 (44.2)	46	1.00	72		1.00
Positive	559 (44.8)	125	2.48 (1.77–3.48)	177		2.30 (1.75–3.02)

^aInconsistency in the total number of cases is due to missing.

IQR: interquartile range. Bold indicates statistically significant values.

Table 2. The associations between ER and histone methylations.

Histone methylations	OR (95%CI)	P
H3K9me1	2.41 (1.68–3.46)	<0.001
H3K9me2	1.82 (1.15–2.81)	0.011
H3K9me3	0.70 (0.49–1.00)	0.048
H3K4me2	1.57 (1.13–2.20)	0.008
H3K4me3	1.04 (0.74–1.45)	0.819
H3K27me3	2.81 (1.99–3.98)	<0.001
H4K20me3	2.43 (1.72–3.43)	<0.001

ER negative was the reference group. The logistic regression model adjusted age at diagnosis, ER status, HER2 status, clinical stage, and histologic grade. Bold indicates statistically significant values.

Table 3. Associations between histone methylations and breast cancer prognosis.

		Overall mortality			Disease progression
Histone methylations	Total (%)	Events	HR (95%CI)	HR (95%CI)^a	Events	HR (95%CI)	HR (95%CI)^a
H3K9me1
≤3.3	278 (26.8)	58	1.00	1.00	87	1.00	1.00
>3.3	761 (73.2)	122	0.70 (0.51–0.96)	0.96 (0.67–1.36)	176	0.68 (0.53–0.88)	0.87 (0.65–1.16)
H3K9me2
≤11.7	143 (14.4)	37	1.00	1.00	51	1.00	1.00
>11.7	850 (85.6)	131	0.54 (0.37–0.77)	0.54 (0.36–0.80)	198	0.58 (0.45–0.74)	0.63 (0.45–0.89)
H3K9me3
≤240	753 (72.9)	143	1.00	1.00	213	1.00	1.00
>240	280 (27.1)	37	0.75 (0.52–1.08)	0.90 (0.61–1.33)	51	0.66 (0.48–0.89)	0.76 (0.54–1.06)
H3K4me2
≤118	482 (46.4)	110	1.00	1.00	155	1.00	1.00
>118	556 (53.6)	70	0.65 (0.48–0.87)	0.63 (0.46–0.88)	109	0.58 (0.45–0.74)	0.66 (0.50–0.86)
H3K4me3
≤275	518 (49.8)	103	1.00	1.00	149	1.00	1.00
>275	522 (50.2)	77	0.65 (0.48–0.87)	0.75 (0.54–1.04)	115	0.68 (0.53–0.87)	0.78 (0.59–1.02)
H3K27me3
≤183.3	329 (31.7)	74	1.00	1.00	104	1.00	1.00
>183.3	710 (68.3)	106	0.63 (0.47–0.84)	0.81 (0.58–1.14)	160	0.66 (0.51–0.84)	0.81(0.61–1.08)
H4K20me3
≤75	494 (47.5)	116	1.00	1.00	157	1.00	1.00
>75	546 (52.5)	64	0.47 (0.34–0.64)	0.58 (0.41–0.81)	107	0.68 (0.53–0.87)	0.66 (0.50–0.88)

^aAdjusting for age at diagnosis, ER status, HER2 status, clinical stage, histologic grade.

Bold indicates statistically significant values.

Table 4. Mediation analysis^a of histone methylations between ER and breast cancer prognosis.

Histone methylations	ACME^b				ADE^c		Total effect^d			Percentage^e (%)
	β	95%CI	P	β	95%CI	P	β	95%CI	P
OS
H3K9me1	−0.63	−24.48–20.26	0.992	144.61	12.55–287.41	0.032	143.98	17.99–285.48	0.032	0.43
H3K9me2	15.00	0.74–35.89	0.030	145.48	0.47–310.50	0.048	160.48	14.34–333.00	0.028	9.35
H3K9me3	−2.45	−18.85–8.68	0.700	137.13	12.45–279.88	0.032	134.68	10.14–276.02	0.032	1.76
H3K4me2	16.80	0.51–42.90	0.036	129.71	−5.62–277.94	0.072	146.51	8.59–298.92	0.038	11.5
H3K4me3	0.85	−8.71–12.71	0.868	136.57	8.37–278.92	0.032	137.41	9.77–278.61	0.034	0.62
H3K27me3	14.76	−11.40–42.44	0.238	123.17	−3.07–267.87	0.058	137.93	9.58–278.56	0.038	10.70
H4K20me3	39.86	10.39–80.71	<0.001	97.25	−47.72–248.21	0.176	137.11	−12.12–288.17	0.062	29.07
PFS
H3K9me1	10.17	−12.58–34.70	0.348	161.19	20.43–304.77	0.022	171.36	38.36–315.25	0.010	5.93
H3K9me2	13.43	0.48–32.48	0.038	169.55	26.38–316.27	0.014	182.98	39.95–338.66	0.010	7.34
H3K9me3	−8.29	−28.76–3.12	0.230	171.85	31.19–318.73	0.014	163.56	22.44–313.57	0.028	4.60
H3K4me2	19.01	0.87–16.14	0.038	156.71	262.02–300.13	0.020	175.72	42.86–328.43	0.008	10.82
H3K4me3	0.94	−10.27–13.68	0.842	169.94	41.55–315.81	0.014	170.88	43.43–319.61	0.012	0.55
H3K27me3	17.67	−9.09–48.17	0.182	145.05	5.18–281.77	0.044	162.72	21.72–296.53	0.016	10.86
H4K20me3	36.35	7.54–77.92	0.010	125.77	2.34–259.15	0.048	162.12	42.21–305.70	0.014	22.42

^aThe CIs in brackets were 95% CIs from 1000 nonparametric bootstrap replicates. The analysis was adjusted for age at diagnosis, HER2, clinical stage, histologic grade.

^bACME, average causal mediation effect.

^cADE, average direct effect.

^dTotal effect, represents the sum of ACME and ADE.

^ePercentage describes the proportion of the effect of ER on the prognosis mediated by histone methylation; Percentage=ACME/[ADE + ACME].

OS: overall survival; PFS: progression-free survival.

Bold indicates statistically significant values.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.