Relationships among KRAS mutation status, expression of RAS pathway signaling molecules, and clinicopathological features and prognosis of patients with colorectal cancer

Table 1 Clinicopathological features of the 220 colorectal patients included in this study

	Patient characteristic	Number of patients	(%)
Gender	Male	113	51.3
	Female	107	48.6
Median age (yr)	< 56	17	7.7
	≥ 56	76	34.5
Tumor site	Right colon	45	20.5
	Left colorectum	175	79.5
Differentiation	Moderate-low	143	65
	Well	77	35
Infiltration depth	T1	13	5.9
	T2	29	13.2
	T3	86	39.1
	T4	92	41.8
Lymph node metastasis	N1-N3	118	53.6
	N0	102	46.4
TNM stage	I	35	15.9
	II	62	28.2
	III	73	33.2
	IV	50	22.7

Table 2 Identification of KRAS mutations

Position	Code name	KRAS gene allele site	Signal channel
A	IR	IR gene FAM	FAM
B	KM1	Exon 12, 34G>T mutation (G12C) FAM, HEX	FAM, HEX
C	KM2	Exon 12, 34G>A mutation (G12S) FAM, HEX	FAM, HEX
D	KM3	Exon 12, 34G>C mutation (G12R) FAM, HEX	FAM, HEX
E	KM4	Exon 12, 35G>T mutation (G12V) FAM, HEX	FAM, HEX
F	KM5	Exon 12, 35G>A mutation (G12D) FAM, HEX	FAM, HEX
G	KM6	Exon 12, 35G>C mutation (G12A) FAM, HEX	FAM, HEX
H	KM7	Exon 13, 38G>A mutation (G13D) FAM, HEX	FAM, HEX

Table 3 Relationship between KRAS and BRAF protein expression and clinicopathological features of colorectal cancer patients

General data		KRAS protein			BRAF protein
		Positive rate (%)	χ²	P-value	Positive rate (%)	χ²	P-value
Median age (yr)	< 56	71 (57/80)	5.34	0.02	77.6 (52/67)	0.10	0.76
	≥ 56	65.9 (83/126)			79.5 (101/127)
Gender	Male	74.3 (84/123)	1.11	0.29	79.5 (89/112)	0.06	0.81
	Female	64.5 (56/83)			78.0 (64/82)
Differentiation	Medium-low	71.6 (106/148)	10.8	0.001	75.7 (106/140)	3.23	0.08
	Well	70.8 (34/48)			87.0 (47/54)
Infiltration depth	T1+T2	63.2 (24/38)	0.21	1.52	79.9 (111/139)	0.28	0.59
	T3+T4	73.4 (116/158)			76.4 (42/55)
Lymph node metastasis	N0	69.6 (64/92)	0.29	0.59	75.0 (69/92)	0.024	0.878
	N1-N3	73.1 (76/104)			74.0 (77/104)
Distant metastasis	M0	70.2 (106/151)	0.49	0.49	75.9 (107/141)	2.96	0.10
	M1	75.6 (34/45)			86.8 (46/53)
TNM stage	Stage I	64 (16/25)	0.79	0.85	75.0 (18/24)	5.98	0.11
	Stage II	71.9 (41/57)			69.5 (41/59)
	Stage III	72.63 (51/70)			82.9 (58/70)
	Stage IV	72.2 (32/44)			87.8 (36/41)

Table 4 Relationship between MEK and ERK protein expression and clinicopathological features of colorectal cancer patients

General data		MEK protein			ERK protein
		Positive rate (%)	P-value	χ²	Positive rate (%)	P-value	χ²
Median age (yr)	< 56	62.9 (44/70)	0.097	0.756	46.5 (33/71)	0.822	0.365
	≥ 56	65.1 (82/126)			53.2 (66/124)
Gender	Male	68.1 (77/113)	1.728	0.189	51.3 (58/113)	0.034	0.855
	Female	59.0 (49/83)			50 (41/82)
Differentiation	Medium-low	64.5(100/155)	0.017	0.896	46 (69/150)	6.012	0.015
	Well	63.4 (26/41)			66.7 (30/45)
Infiltration depth	T1 + T2	68.4 (26/38)	0.356	0.553	51.4 (19/37)	0.006	0.937
	T3 + T4	63.3 (100/158)			48.2 (80/166)
Lymph node metastasis	N0	63.0 (58/92)	0.117	0.733	47.8 (44/92)	0.604	0.437
	N1-N3	65.4 (68/104)			53.4 (55/103)
Distant metastasis	M0	60.3 (91/151)	4.631	0.031	49 (74/151)	0.832	0.362
	M1	77.8 (35/45)			56.8 (25/44)
TNM stage	I	72 (18/25)	5.89	0.117	52.0 (13/25)	2.435	0.487
	II	57.9 (33/57)			43.63 (25/57)
	III	58.6 (41/70)			50 (35/70)
	IV	77.3 (34/44)			59.1 (26/44)

Table 5 Relationship between KRAS genotype and expression of downstream proteins in colorectal cancer tissues

Protein	KRAS mutant type group positive rate	KRAS wild-type group positive rate	χ²	P-value
BRAF	74.2% (46/62)	74.6% (100/134)	0.004	0.948
MEK	54.8% (34/62)	58.2% (78/134)	0.196	0.657
ERK	45.2% (28/62)	54.1% (72/133)	1.364	0.243

Table 6 Correlation between the expression of KRAS and downstream proteins

Protein		KRAS protein positive group	KRAS protein negative group	χ²	P-value
BRAF	76.4% (107/140)		69.6% (39/56)	0.964	0.325
MEK	78.6% (99/126)		58.6% (41/70)	8.775	0.003
ERK	69.6% (78/112)		39.3% (22/56)	4.298	0.038

Table 7 Correlation between expression of BRAF and downstream proteins

Protein	BRAF protein positive group	BRAF protein negative group	χ²	P-value
MEK	67.5% (96/146)	60.0% (30/50)	0.534	0.464
ERK	52.7% (77/146)	46% (23/50)	0.674	0.411

Table 8 Relationship between progression-free survival and KRAS, BRAF, MEK, and ERK protein expression

	B	SE	Wald	df	Sig.	Exp (B)	95.0%CI of Exp (B)
							Lower limit	Upper limit
KRAS	1.200	0.506	5.623	1	0.018	3.319	1.231	8.944
MEK	-0.872	0.609	2.054	1	0.152	0.418	0.127	1.378
ERK	-0.480	0.507	0.898	1	0.343	0.619	0.229	1.670
BRAF	0.031	0.581	0.003	1	0.958	1.031	0.330	3.221
T			4.609	3	0.203
T1	1.330	1.160	1.317	1	0.251	3.783	0.390	36.714
T2	-0.780	0.858	0.827	1	0.363	0.458	0.085	2.463
T3	0.664	0.522	1.617	1	0.203	1.943	0.698	5.408
N	-0.018	0.485	0.001	1	0.970	0.982	0.380	2.541

Table 9 Relationship between overall survival and KRAS, BRAF, MEK, and ERK protein expression

	B	SE	Wald	df	Sig.	Exp (B)	95.0%CI of Exp (B)
							Lower limit	Upper limit
KRAS	0.360	0.536	0.452	1	0.501	1.434	0.501	4.101
MEK	-0.736	0.585	1.586	1	0.208	0.479	0.152	1.506
ERK	-0.571	0.501	1.303	1	0.254	0.565	0.212	1.507
BRAF	0.246	0.539	0.208	1	0.648	1.279	0.444	3.680
T			1.733	3	0.630
T1	1.141	1.114	1.050	1	0.306	3.131	0.353	27.776
T2	-0.356	0.696	0.261	1	0.609	0.701	0.179	2.742
T3	0.230	0.562	0.168	1	0.682	1.259	0.418	3.789
N	0.230	0.503	0.209	1	0.647	1.259	0.470	3.373