Can Mitochondria DNA Provide a Novel Biomarker for Evaluating the Risk and Prognosis of Colorectal Cancer?

Table 2

Association between the D-loop and the risk and prognosis in CRC.

Sample type	Findings	Potential utility	Targets	Ref
CRC tissues ( = 174) and cancer-free controls ( = 170)	The frequencies of 310＇C＇ insertion ( = 0.0078), T16189C ( = 0.0097) variants, and 310＇C＇ins/16189C haplotype ( = 0.0029) in colorectal cancer were significantly higher than that in controls.	Risk evaluation	Nucleotide positions D310 and D16189	[34]
CRC tissues ( = 25)	The D310 mutation was found in 8/25 (32%) CRCs.	Risk evaluation	D310	[46]
Blood samples from 152 CRC patients	The minor haplotype of nucleotides 16290T and frequent haplotype of nucleotide 16298T in the hypervariable segment 1 (HV1) region of the D-loop were associated with high survival rate of CRCs. The nucleotide site of 16290 was identified as independent predictor for CRCs (RR, 0.379; 95% CI, 0.171–0.839; = 0.017).	Risk evaluation and prognosis evaluation	16290T in HV1 region of the D-loop	[47]
CRC tissues ( = 65) and the corresponding noncancerous tissues	The methylation rate of the D-loop region in colorectal cancer tissues was decreased in clinicopathological stages III and IV comparing with that in stages I and II.	Prognosis evaluation	The methylation rate of D-loop	[33]
121 adenomas and seven adenocarcinomas and their corresponding germinal controls	The hypervariable sequence (HV-II) in the loop (D-loop) was significantly associated with the MT-CO2 gene, which represents the early molecular events in MAP (MUTYH-associated polyposis) tumorigenesis.	Risk evaluation and prognosis evaluation	HV-II	[48]
CRC tissues ( = 44) and the corresponding noncancerous tissues	The D-loop of most corresponding noncancerous tissues was methylated and the percentage was 79.5%, while this percentage was much smaller than that in the tumor tissues (11.4%).	Risk evaluation	The methylation rate of D-loop	[32]
Table in the reference	The rate of D-loop mutations in CRCs was higher.	Risk evaluation	D-loop mutations frequency	[37]
Colorectal adenoma tissues ( = 40) and cancer-free controls ( = 150)	The rate of D-loop mutations in CRCs was higher.	Risk evaluation	D-loop mutations frequency	[38]
CRC tissues with p53 mutation ( = 88) and without p53 mutation ( = 106)	The rate of D-loop mutations was higher in CRCs with p53 mutation.	Risk evaluation	D-loop mutations frequency	[39]
64 colorectal adenomas (larger than 10 mm) and from 36 liver metastases of 15 metastatic CRC patients.	The mitochondrial D310 mutations frequency increased in the colorectal adenomas.	Risk evaluation	D310	[36]
Colorectal cancer tissues ( = 25) and the corresponding noncancerous tissues	40.0% (10/25) of the colorectal cancers harbored mutation(s) in the D-loop of mtDNA.	Risk evaluation	D-loop mutations frequency	[41]
Colorectal cancer tissues ( = 77) and the corresponding noncancerous tissues	9% (7/77) of the colorectal cancers harbored mutation(s) in the D-loop region of mtDNA.	Risk evaluation	D-loop mutations	[49]
CRC tissues ( = 35) and the corresponding noncancerous tissues	Polymorphisms located in hypervariable region I (67.9%) more than that in II (32.1%) of D-loop.	Risk evaluation and prognosis evaluation	Polymorphisms in the D-loop	[50]
CRC tissues ( = 95) and cancer-free controls ( = 95)	Thirty-two (34%) CRCs and 2 persons (2%) of the cancer-free controls harbored mutations in the D310 region of D-loop.	Risk evaluation	D310	[51]

The D-loop (mitochondrial displacement loop) was an mtDNA noncoding region and it was as the major control region for the regulation of mitochondrial genome replication and expression. The rate of D-loop mutations, the site of D-loop mutations, and the methylation rate of D-loop were investigated in CRCs. The table has summarized the current main points.