Low-level serum miR-24-2 is associated with the progression of colorectal cancer

Abstract

BACKGROUND:

colorectal cancer (CRC) is the second leading cause of cancer and cancer-related death in the world. Noninvasive biomarkers for early diagnosis of CRC are highly demanded.

OBJECTIVE:

The up-regulation of specific microRNAs (miRNAs) in serum has been considered a promising biomarker of CRC and miR-24-2 may be a potential biomarker in the diagnosis the progression of CRC.

METHODS:

Sixty-eighty healthy subjects and 228 CRC patients were divided into six groups: control group, CRC 0, CRC I, CRC II, CRC III, CRC IV and CRC V. Serum level of miR-24-2 was measured by real-time qPCR. Serum lipid profiles and oxidative-related molecules were also measured.

RESULTS:

Serum levels of miR-24-2 in CRC patients were significantly higher than healthy subjects ( $p<$ 0.05). In addition, the expression level of the miR-24-2 was decreased with the progression of CRC and reached the lowest level in CRC V. Spearman Rank Correlation analysis showed that miR-24-2 level was negatively related to the levels of superoxide dismutase (SOD) and reduced glutathione (GSH), aspartate transaminase (AST), alanine transaminase (ALT), cholesterol and triglyceride ( $p<$ 0.05).

CONCLUSIONS:

Serum miR-24-2 is a potential negative biomarker in the diagnosis of the progression of CRC patients and associated with biochemical indices.

Keywords

miR-24-2 colorectal cancer diagnostic biomarker qRT-PCR

1. Introduction

Colorectal cancer (CRC) is the second leading cause of cancer and cancer-related death in the world, with 2.2 million new cases and 1.1 million deaths each year [1]. Five-year survival rate of the patients with early CRC is close to 71.6%, and if early diagnosis of the disease may be cured [2]. Colonoscopy is widely used in clinical practice and considered to be the gold standard for CRC diagnosis. However, it has many limitations, such as invasive, high cost and cumbersome bowel preparation. In addition, its success depends on the operator’s skills and experience. Therefore, its use in CRC is hampered in most cases. On the other hand, the limited nature of invasive methods such as fecal occult blood test (FOBT) and carcinoembryonic antigen is with poor sensitivity and specificity [3]. Therefore, novel, reliable and noninvasive biomarkers for early diagnosis of CRC are highly demanded.

MicroRNA (miRNA) is a small non-coding RNA with a length of 19–22 nucleotides, which is used as a post-transcriptional regulator by direct cleavage of target messenger RNA (mRNA) or translation inhibition. Many studies have shown that miRNAs can be detected in serum or plasma, and may become a new biomarker for early diagnosis of various cancers [4]. In addition, some miRNAs can distinguish CRC patients from healthy controls and are used to screen CRC as serum biomarkers with high accuracy [5]. However, due to different research methods and test population between laboratories, consistent results are still lacking. According to an earlier report, miR-24-2 controls the genes for initiating cellular stability and survival after screening all the microRNA at human genome level [6]. miR-24-2 targets the genes of cell survival by affecting their methylated profiles and transcription binding sites. Further work has proved that the overexpression of miR-24-2 prevents the progression of MCF-7 breast cancer cell line and suggests a tumor suppressive role of miR-24-2 by inhibiting PKCalpha-related cellular survival [7]. miR-24-2 has also been demonstrated to have tumor suppressive properties [7]. Thus, miR-24-2 may have inhibitory function on CRC patients, but related molecular mechanisms remain unknown. In this study, we investigated serum levels of miR-24-2 in serum samples of CRC patients. At the screening stage, the miR-24-2 levels were analyzed in peripheral sera from CRC patients and healthy controls.

2. Materials and methods

2.1 Participants

All protocols were approved by Ethical and Research Committee of Jinling Hospital (Nanjing, China). Written consent with signed name was obtained from each patient, and the study conforms to The Code of Ethics of the World Medical Association (Declaration of Helsinki) [8]. In addition, the data are collected from confidential certificates obtained from the same hospital. From June 6 ${}^{\rm th}$ , 2014 to July 5 ${}^{\rm th}$ , 2015, 228 patients with CRC were recruited from Jinling Hospital (Nanjing, China). During the same period, 68 healthy volunteers were recruited. In order to avoid result bias, all controls and patients come from the same city (Nanjing, China). All subjects have similar cultural and economic backgrounds.

Table 1
Clinical characteristics of CRC patients and healthy volunteers

		Control	Stage 0	Stage I	Stage II	Stage III	Stage IV
Male	Cases	40	38	30	25	22	13
	Age	56.5 $\pm$ 6.7	55.7 $\pm$ 5.8	56.3 $\pm$ 5.4	55.4 $\pm$ 6.2	56.1 $\pm$ 7.0	57.3 $\pm$ 7.2
	BMI (kg/m ${}^{2}$ )	23.7 $\pm$ 5.0	24.8 $\pm$ 5.6	25.5 $\pm$ 6.1	26.3 $\pm$ 6.5	27.9 $\pm$ 7.1	28.7 $\pm$ 7.6
	Diabetes/Non-diabetes	4/36	3/35	2/28	1/25	3/18	2/11
	High blood pressure/ Normal blood pressure	10/30	6/32	7/23	10/15	11/11	6/7
	Coronary heart disease/ Non-coronary heart disease	6/34	2/36	2/28	3/22	5/17	2/11
	Smoker/Non-smoker	14/26	15/23	12/18	8/17	8/14	4/9
	Drinker/Non-drinker	15/25	14/24	10/20	9/16	6/16	1/12
	During of illness (years)	$-$	1.9 $\pm$ 0.6	2.3 $\pm$ 0.8	2.7 $\pm$ 1.2	3.1 $\pm$ 1.5	3.4 $\pm$ 1.8
	MRI and EUS detection	$-$	4/34	2/28	11/14	18/3	13/1
	Daily calorie intake (kcal)	1945 $\pm$ 273	1997 $\pm$ 302	1882 $\pm$ 263	1899 $\pm$ 311	1832 $\pm$ 251	1849 $\pm$ 297
	Sedentary time (h/d) TV viewing	17/20/2/1	5/15/12/6	2/10/10/8	2/5/10/8	1/5/7/9	1/2/4/6
	L/N/M/H Sitting at work	9/19/11/9	5/16/9/8	1/9/10/10	1/7/7/10	1/4/8/9	0/1/7/5
Female	Cases	28	31	26	17	16	10
	Age	56.9 $\pm$ 6.1	57.1 $\pm$ 6.9	57.8 $\pm$ 6.3	57.7 $\pm$ 6.3	58.1 $\pm$ 7.3	58.5 $\pm$ 7.0
	BMI (kg/m ${}^{2}$ )	24.1 $\pm$ 4.8	25.1 $\pm$ 5.9	26.3 $\pm$ 6.8	26.8 $\pm$ 6.4	28.2 $\pm$ 7.9	28.9 $\pm$ 8.0
	Diabetes/Non-diabetes	3/25	4/27	3/23	3/14	4/12	2/8
	High blood pressure/ Normal blood pressure	6/22	3/28	4/22	2/15	4/12	3/7
	Coronary heart disease/ Non-coronary heart disease	2/26	3/28	4/22	3/14	2/14	4/6
	Smoker/Non-smoker	10/18	10/21	9/17	6/11	5/11	3/7
	Drinker/Non-drinker	12/16	12/19	10/16	8/9	4/12	2/8
	During of illness (years)	$-$	1.5 $\pm$ 0.5	2.3 $\pm$ 0.8	2.5 $\pm$ 1.0	3.2 $\pm$ 1.4	3.6 $\pm$ 1.8
	MRI and EUS detection	$-$	2/29	4/22	6/11	10/6	9/4
	Daily calorie intake (kcal)	1925 $\pm$ 262	1980 $\pm$ 316	1894 $\pm$ 295	1878 $\pm$ 287	1896 $\pm$ 321	1923 $\pm$ 317
	Sedentary time (h/d) TV viewing	11/19/7/3	4/12/9/6	3/10/7/6	1/6/5/5	1/1/6/6	0/1/3/6
	L/N/M/H Sitting at work	5/26/6/3	5/11/10/5	2/10/8/6	1/3/7/6	0/1/6/8	0/0/3/7

Note: MRI, magnetic resonance imaging. EUS, endoscopic ultrasound. The sedentary time was regarded as L if the time spent being sedentary was less than 1.5 h/d. In the same way, 1.5–3.5 h/d was regarded as N, 3.5–6.5 h/d as M and more than 6.5 h/d as H. The situations for the sedentary lifestyles were shown in the order L/N/M/H.

CRC was diagnosed according to the criteria previously reported [9]. Endoscopic submucosal dissection (ESD) is a less invasive therapy for gastric cancer, but is not widely used in the treatment of colorectal rectum due to technique difficulty. The health of the volunteers will be checked in the second half of the year. No injuries were found after all surgical procedures. For all healthy volunteers, they performed normal colorectal endoscopic submucosal dissection, with no tumor symptoms. According to the sedentary time shown in Table 1, CRC patients and healthy volunteers were divided into four groups. In the study, we examined 228 adults (aged 50 to 65 years), who reported a diagnosis of CRC within a year without any other cancers, cardiovascular disease or inflammatory disease. All patients were diagnosed at Jinling hospital. All residents who meet the criteria were diagnosed with histology. Patients with a previous CRC history were excluded. The final phase of the CRC was determined according to the general rules of the International Union Against Cancer (UICC) tumor TNM classification system [10] and classified as five stages (0, I, II, III, IV and V).

2.2 Potential confusing and mediating factors

Potential confounders and intervening factors are found in the association between sedentary lifestyles and obesity, which may be closely related to the risk of CRC. [11]. During the survey, the body mass index (BMI, kg weight divided by the height of the square meter) was measured. Gender differences are reported to be related to the risk of CRC [12]; Smoking [13] and alcohol drinking [14] may lead to a risk of CRC. To avoid age-related issues, all subjects aged between 50 and 65 years of age. All participants reported that food consumption was 3 times/d. Calorie intake was assessed according to a previous report [15].

2.3 RNA extraction

Fresh blood samples (5 ml) were collected from each patient and normal control group at beginning of the present experiment and after one month later. In CRC patients, blood samples were collected and then centrifuged at 1,500 rpm. Hold for 2 min to ensure complete removal of cell debris. Serum samples were stored at $-$ 80 ${}^{\circ}$ C. RNA was isolated from 200 $\mu$ L of serum using a RNA purification kit (Roche, Indianapolis, IN, USA) according to the manufacturer’s instructions. RNA was dissolved in 50 $\mu$ L of RNase-free water and stored at $-$ 80 ${}^{\circ}$ C for further use. The UV spectrophotometer was used to assess the total RNA concentration and purity. Serum RNA concentrations range from 14.6 ng/ $\mu$ l to 45.7 ng/ $\mu$ l.

2.4 Quantitative reverse transcription polymerase chain reaction (qRT-PCR)

Amplification of miRNAs was performed using quantitative reverse primers and polymerase chain reaction (qRT-PCR) specific primers for miR-24-2 (forward primer: 5’-TTGTCTCTGCCTCCCGTG-3’; reverse primer: 5’-GTGCAGGGTCCGAGGT-3’). qRT-PCR was performed on 480 PCR system (Roche), 95 ${}^{\circ}$ C 2 min followed by 45 cycles of 95 ${}^{\circ}$ C for 5 sec, 65 ${}^{\circ}$ C for 15 sec followed by 72 ${}^{\circ}$ C for 30 seconds. The expression of miRNAs in serum samples was calculated using the comparison 2- ${}^{\Delta\Delta}$ Ct method relative to RNU6B (U6) and cel-miR-39 [16].

2.5 Biochemical analysis

Serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were checked by a biochemical analyzer (Beckman, CA, USA). Serum levels of malondialdehyde (MDA) were measured by using an MDA kit (Beyotime, Beijing, China). The serum activities of superoxide dismutase (SOD) and reduced glutathione (GSH) were measured by using the kits from Beyontime. The serum concentrations of aspartate amino-transaminase (AST) and alanine aminotransferase (ALT) were evaluated by the biochemical analyzer.

2.6 Statistical analysis

Differences in miRNA expression between CRC patients and NC were analyzed by using a Mann-Whitney test. The relationship between miRNA and clinical features was estimated by univariate analysis of variance or $\chi$ 2 test. Spearman’s rank correlation coefficient was calculated to confirm the strength of correlation between miR-24-2 and biochemical indices. SPSS (version 20.0, SPSS Inc., Chicago, IL, USA) was used for all statistical analysis. The difference is considered significant when $P<$ 0.05.

Table 2
Biochemical parameters of enzyme activities for CRC

Group ( $n=$ 8)	SOD (U/mL)		GSH (U/L)		ALT (U/mL)		AST (U/mL)
Control	9.25	$\pm$ 4.47 ${}^{\rm c,d,f}$	14.33	$\pm$ 1.64 ${}^{\rm d,e,f}$	45.12	$\pm$ 10.43 ${}^{\rm d,e,f}$	103.32	$\pm$ 25.17 ${}^{\rm d,e,f}$
Stage 0	12.52	$\pm$ 4.53 ${}^{\rm c,d,e,f}$	15.64	$\pm$ 2.28 ${}^{\rm d,e,f}$	47.79	$\pm$ 8.40 ${}^{\rm d,e,f}$	108.26	$\pm$ 19.64 ${}^{\rm d,e,f}$
Stage I	17.68	$\pm$ 2.43 ${}^{\rm a,b,e,f}$	18.28	$\pm$ 1.61 ${}^{\rm e,f}$	43.79	$\pm$ 12.36 ${}^{\rm d,e,f}$	119.42	$\pm$ 24.48 ${}^{\rm d,e,f}$
Stage II	20.34	$\pm$ 3.48 ${}^{\rm a,b,e,f}$	20.38	$\pm$ 1.02 ${}^{\rm a,b,f}$	71.45	$\pm$ 12.18 ${}^{\rm a,b,c,e,f}$	123.24	$\pm$ 17.54 ${}^{\rm a,b,c,f}$
Stage III	22.34	$\pm$ 2.32 ${}^{\rm a,b,c,d,f}$	22.28	$\pm$ 1.74 ${}^{\rm a,b,c,f}$	95.25	$\pm$ 15.82 ${}^{\rm a,b,c,d}$	126.19	$\pm$ 25.28 ${}^{\rm a,b,c,f}$
Stage IV	26.25	$\pm$ 4.16 ${}^{\rm a,b,c,d,e}$	23.23	$\pm$ 1.93 ${}^{\rm a,b,c,d}$	106.34	$\pm$ 12.16 ${}^{\rm a,b,c,d}$	158.63	$\pm$ 22.38 ${}^{\rm a,b,c,d,e}$

Note: Eight blood samples were analyzed in each group. All data are presented as mean value $\pm$ S.D. ${}^{\rm a}p<$ 0.05 vs. the control group; ${}^{\rm b}p<$ 0.05 vs. Stage 0; ${}^{\rm c}p<$ 0.01 vs. the Stag I; ${}^{\rm d}p<$ 0.05 vs. Stage II; ${}^{\rm e}p<$ 0.05 vs. stage III; and ${}^{\rm f}p<$ 0.05 vs. stage IV.

3. Results

3.1 The characteristics of the study object

Two-hundred-twenty-eight patients and 68 healthy volunteers were recruited. Considering the potential confounding factors that contribute to CRC risk, gender and age are not influencing factors (Table 1) ( $P>$ 0.05). There were many other factors that were excluded during the data collection. The study showed the relationship between sedentary time and BMI (Table 1) ( $P<$ 0.01). Watching TV and sitting on the work have a negative impact on the BMI.

The effects of sedentary time on CRC risk were analyzed for the studies listed in Table 1. All CRC patients were diagnosed by a professional physician. The results showed 69 cases in stage 0, 56 cases in stage I, 42 cases in stage II, 38 cases in stage III and 23 cases in stage IV. The severity of CRC is closely related to sedentary time. There was a statistically significant increase in the risk of CRC patients for watching TV. In healthy subjects and stage 0 CRC patients, the four major types of sedentary time were less than other stages (Table 1) ( $p<$ 0.01). In the patients with stage III and IV, the proportion of patients with severe CRC had longer sedative time daily (Table 1) ( $P<$ 0.01). In the majority of CRC patients in stage IV, the daily sedentary time was more than 6 hours daily. It took nearly 16 hours to watch day and sit in the work daily (Table 1). In order to reduce the interference of other factors, a similar age between CRC patients and healthy volunteers was selected. In contrast, healthy volunteers spent less time watching TV and sitting at work daily (Table 1). Healthy volunteers’ sedentary time was shorter than that of CRC patients. The results show that sedentary lifestyles are associated with the risk of CRC.

Figure 1.

The levels of miR-24-2 are associated with the progression of CRC. Horizontal line: average 95% CI. The y-axis represents the relative expression of miRNAs normalized to cel-miR-39. B, at the beginning of the present experiment. A, after one month experiment.

3.2 Serum levels of miR-24-2 is associated with CRC progression

Quantitative RT-PCR analysis showed that the serum levels of miR-24-2 were higher in CRC patients than in controls (Fig. 1, $p<$ 0.05). Furthermore, serum levels of miR-24-2 were increased with the progression of CRC and reached the highest level in CRC stage IV. On the other hand, the serum level of miR-24-2 was stable at the beginning of the present experiment and one month later in each group (Fig. 1, $p>$ 0.05).

3.3 Oxidative stress increases with the progression of CRC

Serum biochemical index analysis showed that serum levels of SOD and GSH were highest in CRC stage IV when compared to all other groups (Table 2) ( $p<$ 0.05). Similarly, ALT and AST were the highest in CRC stage IV when compared to all other groups (Table 2) ( $p<$ 0.05). In contrast, serum levels of SOD, GSH, ALT and AST were lowest in controls (Table 2) ( $p<$ 0.05). Biochemical analysis showed that there was statistical significance of differences for the serum levels of SOD, GSH, ALT and AST among different groups (Table 2) ( $p<$ 0.05).

Table 3
Biochemical parameters of lipid metabolism for NASH (mmol/L)

Group ( $n=$ 8)	TG		TC		HDL-C		LDL-C		MDA
Control	0.84	$\pm$ 0.16 ${}^{\rm b,c,d,e,f}$	2.55	$\pm$ 0.49 ${}^{\rm d,e,f}$	1.36	$\pm$ 0.28 ${}^{\rm c,d,e,f}$	1.13	$\pm$ 0.48 ${}^{\rm c,d,e,f}$	0.48	$\pm$ 0.17 ${}^{\rm c,d,e,f}$
Stage 0	1.26	$\pm$ 0.42 ${}^{\rm a,c,d,e,f}$	2.64	$\pm$ 1.50 ${}^{\rm d,e,f}$	1.27	$\pm$ 0.48 ${}^{\rm d,e,f}$	1.24	$\pm$ 0.66 ${}^{\rm d,e,f}$	0.45	$\pm$ 0.44 ${}^{\rm c,d,e,f}$
Stage I	1.38	$\pm$ 0.32 ${}^{\rm a,b,d,e,f}$	2.84	$\pm$ 1.29 ${}^{e,f}$	1.06	$\pm$ 0.29 ${}^{\rm a,e,f}$	1.39	$\pm$ 0.43 ${}^{\rm a,e,f}$	0.64	$\pm$ 0.37 ${}^{\rm a,b,d,e,f}$
Stage II	1.59	$\pm$ 0.15 ${}^{\rm a,b,c,f}$	3.16	$\pm$ 0.74 ${}^{\rm a,b,f}$	0.92	$\pm$ 0.29 ${}^{\rm a,b,d,f}$	2.10	$\pm$ 0.68 ${}^{\rm a,b,c,f}$	1.06	$\pm$ 0.39 ${}^{\rm a,b,c,f}$
Stage III	1.73	$\pm$ 0.65 ${}^{\rm a,b,c,e,f}$	3.17	$\pm$ 0.53 ${}^{\rm a,b,f}$	0.86	$\pm$ 0.25 ${}^{\rm a,b,f}$	2.13	$\pm$ 0.28 ${}^{\rm a,b,f}$	1.12	$\pm$ 0.36 ${}^{\rm a,b,f}$
Stage IV	1.92	$\pm$ 0.31 ${}^{\rm a,b,c,d}$	3.42	$\pm$ 0.46 ${}^{\rm a,b,c,d}$	0.74	$\pm$ 0.30 ${}^{\rm a,b,c,d}$	2.36	$\pm$ 0.59 ${}^{\rm a,b,c,d,e}$	1.41	$\pm$ 0.28 ${}^{\rm a,b,c,d,e}$

3.4 CRC progression with a worse lipid profile

Lipid pattern analysis showed that serum MDA, TG, TC, and LDL-C reached the highest level in CRC stage IV when compared to other groups (Table 3) ( $p<$ 0.05). In contrast, the serum HDL-C reached the lowest level in CRC stage IV. Comparatively, serum MDA, TG, TC, and LDL-C were at the lowest level and HDL-C was at the highest level in the controls (Table 3) ( $p<$ 0.05). Lipid profile analysis also showed that there was statistical significance of differences for the serum levels of TG, TC, HDL-C, LDL-C and MDA among different groups (Table 3) ( $p<$ 0.05).

Figure 2.

The relationship between miR-24-2 and biochemical parameters. A, the relationship for the serum levels between miR-24-2 and SOD. B, the relationship for the serum levels between miR-24-2 and GSH. C, the relationship for the serum levels between miR-24-2 and ALT. D, the relationship for the serum levels between miR-24-2 and AST. E, the relationship for the serum levels between miR-24-2 and TG. F, the relationship for the serum levels between miR-24-2 and TC. G, the relationship for the serum levels between miR-24-2 and HDL-C. H, the relationship for the serum levels between miR-24-2 and LDL-C. I, the relationship for the serum levels between miR-24-2 and MDA. Statistical analysis was performed by using Spearman’s rank correlation test. The value falls between 0.5 and 1, there is a strong positive correlation. The value falls between $-$ 0.5 and $-$ 1, there is a strong negative correlation. There was significantly statistical difference if $P<$ 0.05.

3.5 The correlation between serum miR-24-2 and biochemical indices

Spearman’s rank correlation coefficient test show that there are strong negative relation between miR-24-2 and SOD (Fig. 2A), GSH (Fig. 2B), HDL-C (Fig. 2G), ALT (Fig. 2C), AST (Fig. 2D), TG (Fig. 2E), TC (Fig. 2F), LDL-C (Fig. 2H) and MDA (Fig. 2I) ( $p<$ 0.05). The results suggest that lipid profiles are improved with the increase of serum miR-24-2.

4. Discussion

In this study, 296 serum samples from 228 CRC patients and 68 control subjects were analyzed. The expression levels of miR-24-2 were predicted to be lowly expressed with the CRC as a tumor suppressor. Recent studies have revealed the diagnostic role of circulating miRNAs in CRC [5, 17]. Unfortunately, independent studies have failed to develop miRNA biomarkers with clinical value for a variety of reasons, including population and sample diversity, the discovery, and validation methods used in these reports. In the present study, low abundance of miR-24-2 was found in advanced CRC. MiR-24-2 was used to analyze the differential expression profiles of serum miRNAs in different-stage CRC and controls. In our study, the screening phase was followed by RT-qPCR validation training and testing phase. Decreased levels of miR-24-2 in serum can be used accurately to distinguish CRC from healthy controls.

Biochemical indices are closely associated with the progression of CRC patients. Oxidative stress is often increased in CRC development and plays an important role in the etiology of CRC and stimulating free radical-related pathways in colorectal carcinogenesis [18]. To control oxidative stress, SOD is often highly expressed in CRC tissues. SOD expression may help to identify patients at high risk for disease outcome and determine the therapeutic method for CRC patients [19]. In the similar case, GSH levels are significantly higher in CRC patients when compared with healthy controls [20]. However, for serum levels of ALT and AST, the situation becomes more complex. The higher levels of ALT [21] and AST are associated with the risks of CRC patients. Lipid profiles are also associated with CRC progression. Elevated serum lipid levels has been found to be associated with the development of distant metastasis in CRC patients [22].

In order to ensure the reliability and repeatability of diagnostic values of miRNA signatures, we further validated our findings by using Spearman’s rank correlation coefficient, which was calculated to confirm the strength of correlation between miR-24-2 and biochemical indices. It is worth noting that the expression of miR-24-2 are strong negatively associated with the serum levels of SOD (Fig. 2A), GSH (Fig. 2B), HDL-C (Fig. 2G), ALT (Fig. 2C), AST (Fig. 2D), TG (Fig. 2E), TC (Fig. 2F), LDL-C (Fig. 2H) and MDA (Fig. 2I) ( $p<$ 0.05). miR-24-2 is associated with the improvement of lipid profiles, indicating important role of miR-24-2 in the prevention of tumorigenesis and progression of CRC.

miR-24-2 may be a potential biomarker for inhibiting other cancers. Previous work demonstrates that combination therapy with miR-24-2 along with an anticancer drug provides a novel way for the patients showing resistant to the medicine by mir-24-2-mediated apoptotic induction in human cancer cells [23]. Overexpressed of pre-miR-24-2 increases miR-24-2 levels in MCF-7 breast cancer cells and indicates tumor suppressive role of miR-24-2 via the inhibition of PKC-alpha-mediated cellular survival [7]. miR-24-2 in sporadic breast tumor has a negative relation with metastasis and increasing nodes. MiR-24-2 targets the genes of cell survival associated with the methylated profiles and transcription factors [6]. All these important molecular mechanisms were not explored in present work. Further studies of miRNA in CRC formation and development are needed in the future.

5. Conclusion

In sum, decreased serum levels of miR-24-2 were demonstrated in poor diagnosis of CRC patients. Low-level serum of miR-24-2 can be used as a noninvasive biomarker in the diagnosis of CRC patients. MiR-24-2 may be clinically applicable to control CRC progression.

Footnotes

Conflict of interest

The authors declare no competing financial interests.

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Low-level serum miR-24-2 is associated with the progression of colorectal cancer

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Materials and methods

2.1 Participants

Table 1 Clinical characteristics of CRC patients and healthy volunteers

2.3 RNA extraction

2.4 Quantitative reverse transcription polymerase chain reaction (qRT-PCR)

2.5 Biochemical analysis

2.6 Statistical analysis

Table 2 Biochemical parameters of enzyme activities for CRC

3.1 The characteristics of the study object

3.3 Oxidative stress increases with the progression of CRC

Table 3 Biochemical parameters of lipid metabolism for NASH (mmol/L)

4. Discussion

5. Conclusion

Footnotes

Conflict of interest

References

Table 1
Clinical characteristics of CRC patients and healthy volunteers

Table 2
Biochemical parameters of enzyme activities for CRC

Table 3
Biochemical parameters of lipid metabolism for NASH (mmol/L)