Circulating miR-221 directly amplified from plasma is a potential diagnostic and prognostic marker of colorectal cancer and is correlated with p53 expression.
OBJECTIVE
Circulating miRNAs exist in serum and plasma and they can be used as a potential noninvasive molecular marker for colorectal cancer (CRC) diagnosis. The present study was to test the availability of direct amplification of miRNAs from plasma without RNA extraction, and to evaluate its clinical application value in CRC.


METHODS
Plasma miR-21, miR-221 and miR-222 levels were determined in 103 CRC patients and 37 healthy normal controls by quantitative reverse transcription-polymerase chain reaction. Immunohistochemical staining for p53, carcinoembryonic antigen (CEA), estrogen receptor (ER) and progesterone receptor (PR) was carried out in the same CRC patient cohort. The correlation between miR-221 levels and protein levels of p53, CEA, ER and PR, clinicopathological features or overall survival was analyzed.


RESULTS
A standard curve shows a good linearity between the log of sample input and C(T) values over three orders of magnitude of plasma miR-21, miR-221 and miR-222. ROC curve analysis reveals that the plasma levels of miR-221 is a potential biomarker for differentiating CRC patients from controls. Kaplan-Meier curve assessment shows that the elevated plasma miR-221 level is a significant prognostic factor for poor overall survival in CRC patients. The immunohistochemistry analysis demonstrates a significant correlation between plasma miR-221 level and p53 expression.


CONCLUSIONS
The direct amplification of plasma miR-221 can be used as a potential noninvasive molecular marker for diagnosis and prognosis of CRC and is correlated with p53 expression.
Pu
Xing-xiang
XX
Department of Medical Oncology, Cancer Center, Sun Yat-sen University, Guangzhou 510060, China.
Huang
Guo-liang
GL
Guo
Hong-qiang
HQ
Guo
Cheng-cheng
CC
Li
Haoran
H
Ye
Shen
S
Ling
Suxia
S
Jiang
Li
L
Tian
Ying
Y
Lin
Tong-yu
TY
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood; D015179:Colorectal Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D035683:MicroRNAs / Q000097:blood* / Q000235:genetics; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012334:RNA, Neoplasm / Q000235:genetics*; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014057:Tomography, X-Ray Computed; D016159:Tumor Suppressor Protein p53 / Q000097:blood / Q000235:genetics*
D014408:Biomarkers, Tumor; D035683:MicroRNAs; D012334:RNA, Neoplasm; D016159:Tumor Suppressor Protein p53; C525709:MIR221, human; C495901:TP53 protein, human