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. 2015 Apr 1;8(4):3882-91.
eCollection 2015.

Expression and clinical significances of Beclin1, LC3 and mTOR in colorectal cancer

Shuhua Wu  1 , Chenbo Sun  1 , Dong Tian  2 , Yangyang Li  2 , Xiangqian Gao  2 , Shuang He  2 , Tangyue Li  2
Affiliations

Expression and clinical significances of Beclin1, LC3 and mTOR in colorectal cancer

Shuhua Wu et al. Int J Clin Exp Pathol. .

Abstract

Autophagy is related to cancer and other diseases, and compromised autophagy could promote chromosome instability associated with carcinogenesis and tumor progression. The role of autophagy in the growth and metastasis of colorectal cancer (CRC) remains poorly understood. Beclin1 mediates autophagic initiation, and LC3 is a specific marker for autophagy. Inactivation of mTOR caused by cellular hypoxia or energy deficiency induces autophagic activity. This study aims to examine the expression and clinical significance of these proteins in CRC. Immunohistochemistry results showed that the positive expression rates of Beclin1, LC3, and mTOR in cancer tissues were 90.50%, 87.19%, and 46.28%, respectively, which were higher than those in adjacent tissues (P < 0.05). Differentiation degree and lymph node metastasis were associated with LC3 overexpression (P < 0.05) but not with Beclin1 (P > 0.05). Lymph node metastasis was also related to mTOR. Spearman analysis results showed that LC3 expression was positively correlated with Beclin1 but negatively correlated with mTOR (r = 0.593 and -0.165, respectively; P < 0.01). Beclin1 expression was also not associated with mTOR (P > 0.05). Survival analysis further indicated that LC3, mTOR, and lymph node metastasis were independent prognostic factors in CRC. Real-time PCR results and Western blot indicated that Beclin1, LC3, and mTOR expression in CRC was significantly higher than that in adjacent tissues (P < 0.01). The aberrant protein expression may be associated with the development and progression of CRC. The LC3 and mTOR genes must be simultaneously detected to evaluate progression and prognosis of CRC.

Keywords: Beclin1; Colorectal cancer; LC3; mTOR; prognosis.

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Figures

Figure 2
Figure 2
Expression of Beclin1, LC3 and mTOR in CRC tissues and counterpart normal colorectal mucosa tissues. 40 cases CRC patients were detected by Real-time PCR (A) and Western blot (B). The data were shown as means ± SE. Significant higher expression of Beclin1 (P<0.01 for mRNA level, P<0.05 for protein level.), LC3 (P<0.01 for mRNA level, P<0.05 for protein level.) and mTOR (P<0.01 for mRNA level, P<0.05 for protein level.) has been found in CRC tissues compared to counterpart normal colorectal mucosa tissues. (C) Proteins extracted from four matched pairs of representative colorectal cancer tissues (T1, 3, 5, and 7) and normal colorectal mucosa tissues (N2, 4, 6, and 8) were subjected to Western blot analysis. The expression of Beclin1, LC3 and mTOR were increased in colorectal cancers compared to counterpart normal colorectal mucosa tissues.
Figure 1
Figure 1
Immunohistochemistry analysis was used to measure the expression of Beclin1, LC3 and mTOR in colorectal cancer and normal colorectal mucosa tissues. Normal colorectal mucosa tissues show no immunoreactivity for Beclin1, LC3 and mTOR (A). Colorectal cancer tissues show immunoreactivity for Beclin1 (B), LC3 (C) and mTOR (D) in the cytoplasm. Magnification: (A-D) ×400.
Figure 3
Figure 3
Kaplan-Meier survival analysis of Beclin1, LC3 and mTOR expression in CRC patients (log-rank test). A. The expression of Beclin1 and overall survival of CRC patients: positive expression [Beclin1 (+)], n = 182, negative expression [Beclin1 (-)], n = 20. B. The expression of LC3 and the overall survival of patients with CRC: positive expression [LC3 (+)], n = 175, negative expression [LC3 (-)], n = 27. C. The expression of mTOR and the overall survival of patients with CRC: positive expression [mTOR (+)], n = 91, negative expression [mTOR (-)], n = 111.
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