Can Serum be Used for Analyzing the KRAS Mutation Status in Patients with Advanced Colorectal Cancer?

Effect of CIP2A and its mechanism of action in the malignant biological behavior of colorectal cancer

Background

Increasing evidence has revealed a close correlation between cancerous inhibitor of protein phosphatase 2A (CIP2A) and cancer progression. CIP2A has been shown to participate in diverse biological processes, such as development, tumorigenic transformation and chemoresistance. However, the functions of CIP2A in colorectal cancer (CRC) and its underlying mechanisms of action are not yet completely understood. The purpose of this study was to explore its clinical significance, function and relevant pathways in CRC.

Methods

Quantitative RT-PCR (qRT-PCR), immunohistochemistry (IHC), western blotting and enzyme-linked immunosorbent assay (ELISA) were used to identify the expression of CIP2A in CRC tissues, sera and CRC cell lines. The association between the expressions of CIP2A and patient survival was analyzed using the Kaplan-Meier curves. Additionally, the functional role of CIP2A in the cell lines was identified through small interfering RNA (siRNA)-mediated depletion of the protein followed by analyses of proliferation and xenograft growth in vivo using short hairpin (sh) RNAs. Effects of the C-myc inhibitor 10,058-F4 on the expressions of C-myc, and CIP2A in CRC cell lines and its potential mechanisms of action were investigated. Finally, the potential molecular pathways associated with CIP2A were screened using the phosphokinase array and identified through western blotting.

Results

CIP2A mRNA and protein levels were upregulated in CRC tissues compared to those of the corresponding normal tissues. It can be used as an independent prognostic indicator to determine overall survival (OS) and disease-free survival (DFS). Depletion of CIP2A substantially suppressed the growth of CRC cells and colony formation in vitro, and inhibited the growth of xenograft tumors in vivo. Additionally, the levels of CIP2A in the sera of patients with CRC were higher than those of the control subjects. Multivariate analyses revealed that the levels of CIP2A in the sera were not independent prognostic indicators in patients with CRC. Moreover, 10,058-F4 could effectively inhibit the growth of CRC cells in vitro, which could be correlated with an inhibition in the expressions of C-myc, CIP2A and its downstream regulatory anti-apoptotic proteins. Furthermore, the Human Phosphokinase Antibody Array was used to gain insights into the CIP2A-dependent intermediary signaling pathways. The results revealed that several signaling pathways were affected and the protein levels of p-p53 (S392), p-STAT5a (Y694), Cyclin D1, p-ERK1/2 and p-AKT (T308) had decreased in CIP2A-shRNA group based on the results of the western blot analysis.

Conclusions

CIP2A could promote the development of CRC cells and predict poor prognosis in patients with CRC, suggesting that it may serve as a potential prognostic marker and therapeutic target against CRC.

The diagnostic accuracy of circulating free DNA for the detection of KRAS mutation status in colorectal cancer: A meta-analysis

KRAS mutations have been reported as a reliable biomarker for epidermal growth factor receptor (EGFR) targeted therapy and are also associated with poor prognosis in colorectal cancer (CRC) patients. However, limitations of detecting KRAS mutations in tissues are obvious. KRAS mutations in the peripheral blood can be detected as an alternative to tissue analysis. The objective of this meta‐analysis was to evaluate the diagnostic value of cfDNA (circulating free DNA) compared with tissues and to investigate the prognostic potential of cfDNA KRAS mutations in CRC patients. Searches were performed in PubMed, Embase, and Cochrane Library for published studies. We extracted true‐positive (TP), false‐positive (FP), false‐negative (FN), true‐negative (TN) values, survival rate of CRC patients with mutant and wild‐type KRAS and calculated pooled sensitivity and specificity, positive/negative likelihood ratios [PLRs/NLRs], diagnostic odds ratios [DORs], and corresponding 95% confidence intervals [95% CIs]. We also generated a summary receiver operating characteristic (SROC) curve to evaluate the overall diagnostic potential. Totally, 31 relevant studies were recruited and used for the meta‐analysis on the efficacy of cfDNA testing in detecting KRAS mutations. The pooled sensitivity, specificity, PLR, NLR, and DOR were 0.637 (95% CI: 0.607‐0.666), 0.943 (95% CI: 0.930‐0.954), 10.024 (95% CI: 6.912‐14.535), 0.347 (95% CI: 0.269‐0.447), and 37.882 (95% CI: 22.473‐63.857), respectively. The area under the SROC curve was 0.9392. Together, the results suggest that detecting KRAS mutations in cfDNA has adequate diagnostic efficacy in terms of specificity. There is a promising role for cfDNA in the detection of KRAS mutations in CRC patients. However, prospective studies with larger patient cohorts are still required before definitive conclusions of the prognostic potential of cfDNA KRAS mutations in CRC patients were drawn.

Prognostic value of circulating cell-free DNA in patients with pancreatic cancer: A systemic review and meta-analysis

Because of the deep research about tumorigenesis mechanism, the cognition of cancer has been transferred to molecular level from morphology. Previous articles reported a potential connection between circulating cell-free DNA (cfDNA) and prognosis of pancreatic cancer. A total of 18 related articles including 1243 patients were enrolled to access the relationship between cfDNA and prognosis of pancreatic cancer. The hazard ratio (HR) was used to combine the univariate and multivariate results of included studies. Our result performed that the cfDNA had significant prognostic value in predicting OS (HR = 2.41, 95%CI: 1.93-3.02, I2 = 60%) and PFS (HR = 2.47, 95%CI: 1.80-3.40, I2 = 0%) in univariate analysis. The multivariate analyses about OS (HR = 2.57, 95%CI: 1.95-3.38, I2 = 66%) and PFS (HR = 2.31, 95%CI: 1.47-3.64, I2 = 0%) also showed significance. In conclusion, the cfDNA was a significant prognostic factor for OS and PFS in patients with pancreatic cancer. The mutation (Kras, ERBB2-exon17 and KrasG12V), circulating tumor DNA (ctDNA) presence, hypermethylation and higher concentration of cfDNA were both associated with worse survival results in pancreatic cancer.

The prognostic value of KRAS mutation by cell-free DNA in cancer patients: A systematic review and meta-analysis

KRAS mutation has been found in various types of cancer. However, the prognostic value of KRAS mutation in cell-free DNA (cfDNA) in cancer patients was conflicting. In the present study, a meta-analysis was conducted to clarify its prognostic significance. Literature searches of Cochrane Library, EMBASE, PubMed and Web of Science were performed to identify studies related to KRAS mutation detected by cfDNA and survival in cancer patients. Two evaluators reviewed and extracted the information independently. Review Manager 5.3 software was used to perform the statistical analysis. Thirty studies were included in the present meta-analysis. Our analysis showed that KRAS mutation in cfDNA was associated with a poorer survival in cancer patients for overall survival (OS, HR 2.02, 95% CI 1.63-2.51, P<0.01) and progression-free survival (PFS, HR 1.64, 95% CI 1.27-2.13, P<0.01). In subgroup analyses, KRAS mutation in pancreatic cancer, colorectal cancer, non-small cell lung cancer and ovarian epithelial cancer had HRs of 2.81 (95% CI 1.83-4.30, P<0.01), 1.67 (95% CI 1.25-2.42, P<0.01), 1.64 (95% CI 1.13-2.39, P = 0.01) and 2.17 (95% 1.12-4.21, p = 0.02) for OS, respectively. In addition, the ethnicity didn't influence the prognostic value of KRAS mutation in cfDNA in cancer patients (p = 0.39). Prognostic value of KRAS mutation was slightly higher in plasma than in serum (HR 2.13 vs 1.65), but no difference was observed (p = 0.37). Briefly, KRAS mutation in cfDNA was a survival prognostic biomarker in cancer patients. Its prognostic value was different in various types of cancer.

Effectiveness of circulating tumor DNA for detection of KRAS gene mutations in colorectal cancer patients: a meta-analysis

Circulating tumor DNA (ctDNA) can be identified in the peripheral blood of patients and harbors the genomic alterations found in tumor tissues, which provides a noninvasive approach for detection of gene mutations. We conducted this meta-analysis to investigate whether ctDNA can be used for monitoring KRAS gene mutations in colorectal cancer (CRC) patients. Medline, Embase, Cochrane Library and Web of Science were searched for the included eligible studies in English, and data were extracted for statistical analysis according to the numbers of true-positive (TP), true-negative (TN), false-positive (FP) and false-negative (FN) cases. Sensitivity, specificity and diagnostic odds ratio (DOR) were calculated, and the area under the receiver operating characteristic curve (AUROC) was used to evaluate the diagnostic performance. After independent searching and reviewing, 21 studies involving 1,812 cancer patients were analyzed. The overall sensitivity, specificity and DOR were 0.67 (95% confidence interval [CI] =0.55-0.78), 0.96 (95% CI =0.93-0.98) and 53.95 (95% CI =26.24-110.92), respectively. The AUROC was 0.95 (95% CI =0.92-0.96), which indicated the high diagnostic accuracy of ctDNA. After stratified analysis, we found the higher diagnostic accuracy in subgroup of patients detected in blood sample of plasma. The ctDNA may be an ideal source for detection of KRAS gene mutations in CRC patients with high specificity and diagnostic value.