Alpha B-crystallin correlates with poor survival in colorectal cancer

Abstract

Alpha B-crystallin (CRYAB) is primarily found as major structural proteins of the ocular lens and is a principal member of the small heat shock protein (HSP) family. So far, CRYAB has been suggested to play critical roles in the development of several kinds of human cancers. However, the association between CRYAB expression and clinicopathological characteristics of colorectal cancer (CRC) has not been elucidated yet. In the present study, one-step quantitative PCR reverse transcription-polymerase chain reaction (qPCR) analysis of 18 samples of CRC and immunohistochemistry (IHC) analysis with 100 cases of CRC sample in tissue microarrays (TMA) were employed to evaluate the expression of CRYAB in CRC. The results suggested that CRYAB expression in the mRNA and protein levels was significantly higher in CRC tissues than in corresponding non-cancerous tissues (P < 0.05 and P = 0.014, respectively). The expression of CRYAB protein in CRC was significantly associated with distant metastasis (P = 0.040) and overall survival (P = 0.003). Kaplan-Meier method and multivariate survival analysis indicated that high expression of CRYAB (P = 0.040) and distant metastasis (P = 0.005) showed significant correlations with poor prognosis of CRC patients. The data imply that CRYAB expression is correlated with substantial clinical characteristics of CRC, and it may be identified as an unfavorable prognostic factor for CRC.

Keywords: CRC; CRYAB; IHC; TMA; qPCR.

Figure 1

One-step quantitative real-time polymerase chain reaction (qPCR) was performed to evaluate the expression of CRYAB mRNA in colorectal cancer (CRC) tissues and matched non-cancerous tissues. Expression of CRYAB mRNA in CRC tissues (4.19 ± 0.351) was significantly higher than that of in matched tumor adjacent non-cancerous tissues (1.16 ± 0.160) (P < 0.05), when normalized to the GAPDH internal control.

Figure 2

Representative figures of CRYAB protein expression in colorectal cancer (CRC) tissues and non-cancerous tissues by immunohistochemistry (IHC) analysis. A1 and A2. High expression of CRYAB in nucleus of CRC cells. B1 and B2. High expression of CRYAB in cytoplasm of CRC cells. C1 and C2. Low expression of CRYAB in CRC cells. D1 and D2. High expression of CRYAB in non-cancerous cells. E1 and E2. Low expression of CRYAB in non-cancerous cells. Magnification ×40 in A1, B1, C1, D1 and E1; ×400 in A2, B2, C2, D2 and E2.

Figure 3

Survival analysis of 100 colorectal cancer (CRC) patients by Kaplan-Meier method. A. Overall survival rate in patients with high CRYAB expression (green line) was significantly lower than that in patients with low CRYAB expression (blue line). B. Overall survival rate in patients with positive distant metastasis (green line) was significantly lower than that in patients with negative distant metastasis (blue line).