The potential of cytokeratin 20 and mucin 2 mRNA as metastasis markers in regional lymph nodes of colon cancer patients investigated by quantitative RT-PCR

Expression profiling and intracellular localization studies of the novel Proline-, Histidine-, and Glycine-rich protein 1 suggest an essential role in gastro-intestinal epithelium and a potential clinical application in colorectal cancer diagnostics

Background

The primary function of the intestines is the absorption of water and nutrients. Although our knowledge about these processes on the cellular level is extensive, a number of important intracellular elements remain unknown. Here, we characterize the novel proline-, histidine-, glycine-rich 1 (PHGR1) mRNA and protein on the molecular level and propose a functional role of the PHGR1 protein in the intestinal and gastric epithelium.

Methods

PHGR1 mRNA and protein expression in human tissues and cell lines were characterized by quantitative RT-PCR, in situ hybridization, Northern blotting, Western blotting, and immunohistochemistry. Glycosylation was assessed by a chemical deglycosylation assay, whereas intracellular localization was studied by immunofluorescent staining of cell line cells. PHGR1 mRNA levels in HT29 cells was reduced by RNA interference and the resulting global changes in gene expression assessed by microarray hybridization.

Results

PHGR1 mRNA and protein were found to be expressed specifically in epithelial cells of intestinal mucosa, with the highest expression in the most mature and differentiated cells. PHGR1 protein was found to be glycosylated and to localize to both the cytoplasm and nucleus. Transcript profiling and gene ontology analysis of HT29 cells subjected to PHGR1 knockdown suggested a functional relationship with transport and metabolic processes. Examination of PHGR1 mRNA and protein levels in lymph nodes with known colorectal cancer metastases indicated that they may serve as biomarkers for detection of such metastases.

Conclusions

Functional analyses of the novel PHGR1 mRNA and protein suggest an essential role in gastrointestinal epithelium and a clinical application in detection of colorectal cancer lymph node metastases.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0752-8) contains supplementary material, which is available to authorized users.

Prognostic Value of Molecular Detection of Lymph Node Metastases After Curative Resection of Stage II Colon Cancer: A Systematic Pooled Data Analysis

BACKGROUND

We aimed to clarify the prognostic value of guanylyl cyclase C (GCC) lymph node ratio (LNR) status as a predictor of recurrence in untreated stage IIA colon cancer on the basis of pooled individual data from previous studies.

METHODS

Patients were classified according to predefined GCC LNR risk groups (low, LNR ≤ 0.1; intermediate, 0.1 < LNR ≤ 0.2; high, LNR > 0.2). Outcomes included time to recurrence, disease-free survival, and overall survival. Stratified log-rank tests and multivariate Cox models assessed the association between outcomes and GCC lymph node status.

RESULTS

The final data set contained 553 patients with stage IIA colon cancer with a median of 18 lymph nodes examined after resection; 65 patients (11.8%) had recurrence. Overall, 109 patients (19.7%) were classified high risk on the basis of GCC LNR. In multivariate analysis, high GCC LNR value (> 0.2) was a significant predictor of cancer recurrence (hazard ratio [HR], 3.18; 95% confidence interval [CI], 1.77-5.71; P < .001) and lower disease-free survival (HR, 2.40; 95% CI, 1.60-3.62; P < .001) and overall survival (HR, 2.12; 95% CI, 1.35-3.33; P = .001).

CONCLUSION

Patients considered at high risk on the basis of their GCC LNR status have significantly inferior outcomes compared to those with low GCC LNR values, particularly among those traditionally considered to be at low risk for recurrence.

Comparison of CpG island methylator phenotype (CIMP) frequency in colon cancer using different probe- and gene-specific scoring alternatives on recommended multi-gene panels

Background

In colorectal cancer a distinct subgroup of tumours demonstrate the CpG island methylator phenotype (CIMP). However, a consensus of how to score CIMP is not reached, and variation in definition may influence the reported CIMP prevalence in tumours. Thus, we sought to compare currently suggested definitions and cut-offs for methylation markers and how they influence CIMP classification in colon cancer.

Methods

Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), with subsequent fragment analysis, was used to investigate methylation of tumour samples. In total, 31 CpG sites, located in 8 different genes (RUNX3, MLH1, NEUROG1, CDKN2A, IGF2, CRABP1, SOCS1 and CACNA1G) were investigated in 64 distinct colon cancers and 2 colon cancer cell lines. The Ogino gene panel includes all 8 genes, in addition to the Weisenberger panel of which only 5 of the 8 genes included were investigated. In total, 18 alternative combinations of scoring of CIMP positivity on probe-, gene-, and panel-level were analysed and compared.

Results

For 47 samples (71%), the CIMP status was constant and independent of criteria used for scoring; 34 samples were constantly scored as CIMP negative, and 13 (20%) consistently scored as CIMP positive. Only four of 31 probes (13%) investigated showed no difference in the numbers of positive samples using the different cut-offs. Within the panels a trend was observed that increasing the gene-level stringency resulted in a larger difference in CIMP positive samples than increasing the probe-level stringency. A significant difference between positive samples using ‘the most stringent’ as compared to ‘the least stringent’ criteria (20% vs 46%, respectively; p<0.005) was demonstrated.

Conclusions

A statistical significant variation in the frequency of CIMP depending on the cut-offs and genes included in a panel was found, with twice as many positives samples by least compared to most stringent definition used.

Lymph node staging in colorectal cancer: Old controversies and recent advances

Outcome prediction based on tumor stage reflected by the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) tumor node metastasis (TNM) system is currently regarded as the strongest prognostic parameter for patients with colorectal cancer. For affected patients, the indication for adjuvant therapy is mainly guided by the presence of regional lymph node metastasis. In addition to the extent of surgical lymph node removal and the thoroughness of the pathologist in dissecting the resection specimen, several parameters that are related to the pathological work-up of the dissected nodes may affect the clinical significance of lymph node staging. These include changing definitions of lymph nodes, involved lymph nodes, and tumor deposits in different editions of the AJCC/UICC TNM system as well as the minimum number of nodes to be dissected. Methods to increase the lymph node yield in the fatty tissue include methylene blue injection and acetone compression. Outcome prediction based on the lymph node ratio, defined as the number of positive lymph nodes divided by the total number of retrieved nodes, may be superior to the absolute numbers of involved nodes. Extracapsular invasion has been identified as additional prognostic factor. Adding step sectioning and immunohistochemistry to the pathological work-up may result in higher accuracy of histological diagnosis. The clinical value of more recent technical advances, such as sentinel lymph node biopsy and molecular analysis of lymph nodes tissue still remains to be defined.

An optimal mRNA marker for OSNA (One-step nucleic acid amplification) based lymph node metastasis detection in colorectal cancer patients

BACKGROUND

We previously reported that the one-step nucleic acid amplification assay is effective for lymph node metastasis detection in breast cancer patients. This paper describes the identification of CK19 mRNA as an optimal marker and its cut-off value for use in the detection of one-step nucleic acid amplification-based lymph node metastasis in colorectal cancer patients.

METHODS

Candidate mRNA markers selected from the genome-wide expressed sequence tag database were evaluated by quantitative RT-PCR using a mixture of metastasis-positive and another mixture of metastasis-negative lymph nodes (n = 5 each), followed by quantitative RT-PCR using metastasis-positive and -negative lymph nodes (n = 10 each) from 20 patients. The one-step nucleic acid amplification assay for mRNA markers selected above was examined using 28 positive lymph nodes from 19 patients and 38 negative lymph nodes from the 11 pN0 patients.

RESULTS

Quantitative RT-PCR analyses of the 98 mRNAs selected from the genome-wide expressed sequence tag database and the subsequent quantitative RT-PCR analyses of the nine mRNAs selected above indicated that CK19 and CEA mRNAs have the highest capability for distinguishing between positive and negative lymph nodes. CK19, CEA and CK20 mRNAs were evaluated by the one-step nucleic acid amplification assay. An area under a receiver-operating-characteristic curve for CK19 mRNA (0.999) was slightly larger than that for CEA mRNA (0.946; P = 0.062) and significantly larger that than for CK20 mRNA (0.875; P = 0.006).

CONCLUSION

We found that CK19 mRNA has the best diagnostic performance and its cut-off value for discriminating positive from negative lymph nodes can be set in the range of 75-500 copies/µl with 96.4% sensitivity and 100% specificity.

Prognostic relevance of occult metastases detected by cytokeratin 20 and mucin 2 mRNA levels in sentinel lymph nodes from colon cancer patients

PURPOSE

To investigate the prognostic value of occult metastases detected by quantitative measurements of candidate biomarkers in sentinel lymph nodes (SLNs) from patients curatively resected for colon cancer.

METHODS

Resection specimens from consecutive patients undergoing surgery for localized colon cancer were subjected to ex vivo SLN mapping. SLNs were examined for the presence of metastases by routine hematoxylin-erythrosin-safranin staining and by cytokeratin 20 (CK20) and mucin 2 (MUC2) mRNA quantification. The patients were stratified according to KRAS and BRAF mutation status and microsatellite instability status in their primary tumors. Survival end points were analyzed by Kaplan-Meier survival estimates and log-rank tests.

RESULTS

A total of 817 SLNs were identified in 206 (97 %) of the 213 included patients. Routine histological examination of SLNs and other regional lymph nodes identified 63 patients with positive nodes (pN+), of which 42 (67 %) were positive in one or more SLNs (sensitivity 67 %, false-negative rate 33 %). On the basis of the CK20 and MUC2 mRNA levels in SLNs, occult metastases were suggested in 86 (60 %) and 52 (36 %) of the 143 otherwise LN-negative (pN0) patients, respectively. Survival analysis with a median 3.6-year follow-up revealed that MUC2 mRNA quantification had significant prognostic value in SLNs from all patients; however, occult SLN metastasis detection did not.

CONCLUSIONS

Occult SLN metastases detected by CK20 and MUC2 mRNA quantification had limited prognostic value.

Caco-2 and LS174T cell lines provide different models for studying mucin expression in colon cancer

To compare the differences in MUC2 and MUC5AC mRNA among four colon cancer cell lines and to identify the best in vitro models for studying mucin expression, quantitative real-time polymerase chain reaction was used to measure the expression of MUC2 and MUC5AC mRNA in Caco-2, HT29, LoVo, and LS174T cell lines. The levels of MUC2 mRNA expression in the four colon cancer cell lines ranked in order of mRNA abundance were: LS174T>LoVo>HT-29>Caco-2. In contrast to MUC2, the abundances of MUC5AC mRNA were in the order: Caco-2>HT-29>LS174T>LoVo. Caco-2 (highest level of MUC5AC mRNA) and LS174T (highest level of MUC2 mRNA) were used to investigate the phenotypes. Morphologically, Caco-2 cells were larger with low electron density mucus-storing vacuoles, many cell surface microvilli, and no obvious intercellular spaces between cells, compared to LS174T cells. The proliferative and invasive capacities of LS174T cells were significantly higher than those of Caco-2 cells. Caco-2 and LS174T cells provide excellent in vitro models for studying mucin expression in colon cancer.

Prognostic significance of MAGE in peritoneal washes in gastric carcinoma patients without peritoneal metastasis: results of a 5-year follow-up study

GOALS

The RT-PCR assay of peritoneal washes has been used to predict peritoneal metastasis of gastric carcinoma. We used melanoma associated gene (MAGE) RT-PCR to detect peritoneal metastasis of gastric carcinoma after curative surgery and evaluated its clinical significance.

METHOD

Eighty-four peritoneal washes and 23 tumor and normal tissues were obtained from 84 gastric carcinoma patients. MAGE A1-A6 RT-PCR was carried out, and the results were evaluated according to their clinicopathologic characteristics. Five-year follow-up clinical studies were carried out periodically, and overall survival rates were retrospectively investigated using medical records.

RESULTS

For the paired tumor and normal tissues, MAGE expression rates were 65.2% and 4.3%, respectively. In peritoneal fluids, 11 cases (13.1%) revealed MAGE expression, and higher MAGE expression rates were observed with young age, deeper invasion, and advanced stages of tumor groups. MAGE-positive cases had much higher recurrence rates than MAGE-negative cases (45.5% vs. 9.6%, P<0.002). Among T-stage, N-stage, and MAGE expression; MAGE expression was determined to be the most important prognostic factor for overall survival rate by Cox proportional hazard model analysis.

CONCLUSION

MAGE RT-PCR results for peritoneal fluid disclosed significant associations with peritoneal recurrence of gastric carcinoma and proved to be the most important factor for overall survival rate in gastric carcinoma patients who had undergone radical resection.

Extended lymph node dissection in colorectal cancer surgery. Reliability and reproducibility in assessments of operative reports

BACKGROUND

Stratification of surgical strategies or techniques by operative reports is rarely validated. This study evaluates the assessment of lymph node dissection from operative reports and the possible survival benefit of extended lymph node dissection.

METHODS

The operative reports of 342 colorectal resections (R0) were assessed twice by two surgeons. The lymph node dissection was classified as limited or extended according to a novel scheme. Intraobserver reproducibility and interobserver reliability were evaluated by kappa (kappa) statistics and a Cox model.

RESULTS

For colonic resections, the reproducibility of assessments was moderate or substantial (kappa: 0.42-0.75), and the reliability was moderate (kappa: 0.54-0.58). For rectal resections, reproducibility was moderate (kappa: 0.45-0.58), and reliability was fair (kappa: 0.29-0.36; all kappa values: p < 0.001). The 5-year survival rates of colonic cancer patients subject to a limited or extended procedure were 52% (45-60%, 95% confidence interval) and 69% (53-84%; p = 0.034), respectively. The hazard ratios of extended lymph node dissection (limited as reference) were 0.34 (0.14-0.86; p = 0.023) for stage I and II and 1.11 (0.50-2.44) for stage III. In rectal cancer patients, the 5-year survival rates of a limited or extended procedure were 63% (54-72%) and 55% (37-73), respectively.

CONCLUSIONS

Valid assessment of lymph node dissection can be obtained from operative reports. Extended lymph node dissection improves long-term survival rates of colonic cancer patients.

Quantitative RT-PCR detection of tumor cells in sentinel lymph nodes isolated from colon cancer patients with an ex vivo approach

OBJECTIVE

To investigate quantitative RT-PCR-based detection of tumor cells in lymph nodes (LNs) isolated from colon cancer patients by ex vivo sentinel lymph node (SLN) mapping.

SUMMARY BACKGROUND DATA

Although lymph node status is among the strongest prognostic factors in colon cancer patients, 20% to 30% of node negative patients experience disease recurrence. These patients may have LN metastases that are not detected by routine examination.

METHODS

Ex vivo SLN mapping was applied to 131 prospectively recruited patients undergoing curative surgery for primary colon cancer. The SLNs were analyzed for the presence of tumor cells by routine histology and real-time RT-PCR quantitation of cytokeratin 20 (CK20) and mucin 2(MUC2) mRNA.

RESULTS

SLNs were identified in 125 (95%) of the 131 patients included.Routine histologic analysis of SLNs and other regional lymph nodes revealed LN metastases in 42 patients (N+), of which 29 (69%) had metastases detected in 1 or more SLNs (sensitivity, 69%; false negative rate, 31%).When analyzing the SLNs by quantitative RT-PCR, the sensitivity, compared with routine LN examination, was 37/42 (88%) for both the CK20 and the MUC2 mRNA markers. In addition, 46% and 27% of the patients' node negative by routine LN examination (N0) were positive for the CK20 and MUC2 mRNA markers, respectively, possibly reflecting the presence of occult tumor cells in their SLNs.

CONCLUSIONS

Quantitative RT-PCR analysis of SLNs identified N+ patients with high sensitivity and revealed a subgroup of N0 patients with potential occult LN disease.