A variant in 3′-untranslated region of KRAS compromises its interaction with hsa-let-7g and contributes to the development of lung cancer in patients with COPD

Figures & data

Table 1 Clinicopathological characteristics of the participants in this study

	COPD (+) Lung cancer (−) (N=422)	COPD (+) Lung cancer (+) (N=132)	P-value
Sex (M/F)	390/52	108/24	0.0582
Age (years)	66.7±12.8#	65.2±9.6#	0.215
Smoking status
Smokers	183	68	0.0856
Ex-smokers	208	54
Smoking index	32.5±11.2#	34.5±8.7#	0.060
COPD severity
Mild	170	33	,0.001
Moderate	165	45
Severe	66	33
Very severe	21	21
Lung cancer type
Squamous		75
Adenocarcinoma		36
Large cell		11
Small cell		10

Note:

# Data is mean ± standard deviation.

Table 2 Statistical analysis of the association between the rs712 polymorphism genotype and the presence of lung cancer in COPD patient

	COPD (+) Lung cancer (−) (N=422)	COPD (+) Lung cancer (+) (N=132)	P-value	Adjusted OR (95% CI)
TT	278 (65.87%)	72 (54.54%)	0.0282	1.00
TG	132 (31.27%)	38 (28.79%)		1.11 (0.71–1.73)
GG	12 (2.86%)	22 (16.67%)		7.07 (3.34–14.97)
Combined
TT/TG	410 (97.14%)	110 (83.33%)	0.0081	1.00
GG	12 (2.86%)	22 (16.67%)		6.83 (3.27–14.24)

Abbreviations: OR, odds ratio; CI, confidence interval.

Figure 1 Schematic sequence comparison of KRAS 3′-UTR and primary let-7g and location of rs712 polymorphism in the 3′-UTR of KRAS.

Abbreviations: MUT, mutant; UTR, untranslated region; WT, wild-type.

Figure 2 Evaluation of rs712 polymorphism on the interaction between let-7g and KRAS 3′-UTR.

Notes: (A) Relative luciferase activity in let-7g over-expressing H226 cells transfected with empty vector, wild-type KRAS 3′-UTR, or mutant KRAS 3′-UTR (**P<0.01, compared with the empty vector; ^##P<0.01, compared with the empty vector). (B) Relative luciferase activity in let-7g over-expressing H522 cells transfected with empty vector, wild-type KRAS 3′-UTR, or mutant KRAS 3′-UTR (**P<0.01, compared with the empty vector; ^##P<0.01, compared with the empty vector).
Abbreviations: Luc, luciferase; WT, wild-type; UTR, untranslated region; Mut, mutant.

Figure 3 Determination of expression of KRAS in lungs of each genotype group by using immunohistochemistry.

Notes: Expression of KRAS was comparable between TT (A), TG (B), and GG (C) groups.

Figure 4 Determination of the expression of KRAS in each genotype group.

Notes: (A) Determination of expression of let-7g in lungs in each genotype group (TT, n=17; TG, n=12; GG, n=6) by using real-time PCR. (B) Determination of mRNA expression of KRAS in lungs in each genotype group (TT, n=17; TG, n=12; GG, n=6); (C) Determination of protein expression of KRAS in lungs in each genotype group (TT, n=17; TG, n=12; GG, n=6) by using Western blot. (D) Densitometry analysis of the results of Western blot (**P<0.01, compared with wild type, TT).

Abbreviation: PCR, polymerase chain reaction.

Figure 5 Determination of the expression levels and activities of total AKT and p-AKT in each genotype group.

Notes: (A) Determination of mRNA expression of ATK in lungs in each genotype group (TT, n=17; TG, n=12; GG, n=6). (B) Determination of total protein expression of ATK in lungs in each genotype group (TT, n=17; TG, n=12; GG, n=6) by using Western blot. (C) Determination of phosphorylation level of ATK in lungs in each genotype group (TT, n=17; TG, n=12; GG, n=6) by using Western blot. (D) Densitometry analysis of the results of Western blot described in (B). (E) Densitometry analysis of the results of Western blot described in (C) (**P<0.01, compared with wild type, TT).