The biology of colorectal cancer metastasis

Colorectal Cancer Pulmonary Metastasectomy: When, Why and How

Colorectal cancer is the third-most-diagnosed cancer in males and in females, representing 8% of estimated new cases, and the third cause of cancer-related death in both sexes, accounting for 9% of cancer deaths in men and 8% in women. About 20% of patients diagnosed with CRC present metastatic disease. Although lung metachronous or synchronous metastatic spread without other involved sites has been reported in only a small proportion of patients, considering that this tumor is frequently diagnosed, the clinical approach to CRC pulmonary metastases represents a major issue for thoracic surgeons and CRC oncologists. Among patients diagnosed with pulmonary metastases from CRC, about 9-12% are eligible for local treatments with radical intent, including surgical resection, SBRT (stereotactic body radiation therapy) and ablation therapy. Due to the lack of randomized controlled trials among different local strategies, there is no definitive evidence about the optimal approach, although surgical resection is considered the most effective therapeutic option in this clinical scenario. Oncological achievement of primary radical resection, the biology of primary tumor and metastatic sites, disease free interval and or progression free survival are independent prognostic factors which make it possible to define a cohort of patients which might significantly benefit from pulmonary metastasectomy.

Angiogenesis factors involved in the pathogenesis of colorectal cancer

Colorectal cancer stands at the top of oncologic pathology in the world, and in the same measure in Romania because is the third most frequent cancer diagnosed in men and women. Colorectal cancer develops as a result of mutations in genes that control proliferation and cell death. It was established that in the development of a tumor there is originally a prevascular phase followed by a phase of tumor angiogenesis. In the future it is necessary to develop new clinical protocols that angiogenesis inhibitors are associated with chemo or radiotherapy, conventional or other methods such as immunotherapy and gene therapy.

The utility of serum receptor-binding cancer antigen expressed on SiSo cells in gastrointestinal tract cancers

BACKGROUND

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a novel tumour marker that has been described in various kinds of cancer. The majority of observations include immunohistochemical studies; however, there are not enough data about the utility of this antigen as a serum tumour marker and its tumour specificity.

AIM

To measure the serum levels of RCAS1 in patients with gastrointestinal (GI) tract cancers and compare them with other GI tract tumour markers.

PATIENTS AND METHODS

Sera collected from patients with GI cancers (14 esophagus, 32 gastric and 36 colon) and from healthy volunteers (30 individuals) were analyzed for RCAS1 and compared with carcinoembryonic antigen (CEA) and cancer antigen 19-9. The relationship between serum RCAS1, tumour stage and tumour grade was also evaluated.

RESULTS

Mean serum RCAS1 level was higher in patients with GI tract cancers compared with the control group (P=0.001). Among GI tract cancers, RCAS1 had lowest and highest sensitivity for esophagus and colon cancer diagnosis, respectively. Serum RCAS1 had a higher sensitivity for malignancy, except in the colon, and lower specificity in all groups compared with CEA. In comparison with cancer antigen 19-9, serum RCAS1 was more sensitive but less specific for all GI cancer groups. Mean serum RCAS1 levels were not statistically significant among histopathological tumour types (P>0.05). Although serum RCAS1 levels were significantly higher in cases with lymph node involvement compared with lymph node-negative cases (P=0.009), there was no difference between cases with and without serosal involvement, vascular invasion and distant metastasis; no correlation was found between tumour size and RCAS1 levels.

CONCLUSIONS

RCAS1 may be used and combined with CEA as a tumour marker in GI tract cancers.

Galectin-3 modulates MUC2 mucin expression in human colon cancer cells at the level of transcription via AP-1 activation

BACKGROUND & AIMS

Galectin-3 and MUC2 intestinal mucin each have been correlated with the malignant behavior of colon cancer cells. Galectin-3 modulates expression of MUC2 protein, but the specific regulatory mechanisms are unknown. This study sought to determine how galectin-3 increases MUC2 expression.

METHODS

Galectin-3 levels in human colon cancer cells of high and low metastatic ability were manipulated via expression of galectin-3 complementary DNA in sense or antisense orientation. Galectin-3 and MUC2 protein expression were determined by Western analysis and immunocytochemistry. Transient transfections of promoter reporter constructs were used to monitor MUC2 transcription and AP-1 activity. Electrophoretic mobility shift assays, site-directed mutagenesis, and chromatin immunoprecipitation were used to monitor the participation of AP-1 in MUC2 transcription.

RESULTS

Alterations in galectin-3 levels correlated with both MUC2 protein expression and transcription. By using MUC2 promoter constructs of different lengths, galectin-3 responsiveness was found between 1500 and 2186 bp upstream of the translation start site, a region that contains 1 consensus AP-1 binding site. AP-1 activity paralleled MUC2 transcription in the different cell lines. Mutation in the AP-1 site markedly decreased MUC2 promoter activity, and MUC2 transcription was inhibited by cotransfection with a dominant-negative AP-1 vector. Electrophoretic mobility shift assays, co-immunoprecipitation, and chromatin immunoprecipitation analyses suggested an association between galectin-3, c-Jun, and Fra-1 in forming a complex at the AP-1 site on the MUC2 promoter.

CONCLUSIONS

Galectin-3 up-regulation of MUC2 transcription occurs at the level of transcription through AP-1 activation. This may have important implications for understanding the role of galectin-3 and MUC2 in colon cancer metastasis.

Valores séricos de factor de crecimiento del endotelio vascular en pacientes con cáncer colorrectal y su significación pronóstica

BACKGROUND AND OBJECTIVE

Thirty per cent of patients with histologically node-negative colorectal cancer die from disseminated disease. Actually disease stage is the most useful prognostic parameter although it is not sufficient. Vascular endothelial growth factor (VEGF) is an angiogenic cytokine involved in the progression of tumors. In our study we tried to know the prognostic significance of pre and postoperative serum VEGF levels in patients with colorectal cancer.

PATIENTS AND METHOD

Cohort study that included 52 patients with colorectal cancer surgically treated in our Department from 1998 to 2000. Serum VEGF and CEA levels were determined the day before surgery and 30 days after it.

RESULTS

Preoperative serum VEGF levels (428.5 [38.5] pg/ml) were higher than in control patients (p=0.008). Serum VEGF levels fallen significantly after surgery (343 [31.2] pg/ml; p=0.001). Pre and postoperative serum VEGF levels in poorly differentiated neoplasms were higher than in well differentiated ones (p=0.009 and p=0.008 respectively). Pre and postoperative serum CEA and VEGF levels were significantly associated with cancer relapse (p=0.037, p=0.017, p=0.048 and p=0.001, respectively). In multivariate analysis only postoperative serum VEGF levels were associated with colorectal cancer relapse (p=0.003; HR=1.007; 95% CI, 1.002-1.012). Pre and postoperative CEA levels (p<0.001 and p=0.001 respectively) and postoperative VEGF levels (p=0.001), were associated with mortality. In multivariate analysis only tumor stage (p=0.01) and postoperative serum VEGF levels (p=0.02) were associated with mortality. Postoperative serum VEGF determination and pre and postoperative CEA levels raise specificity and positive predictive values to 100% in relation to mortality.

CONCLUSIONS

Pre and postoperative serum VEGF determination has prognostic significance, regardless of tumor stage, in patients with colorectal cancer. In survival methods, postoperative VEGF levels >343 pg/ml are significantly with tumor relapse and mortality. These results suggest the use of serum VEGF levels as a prognostic and monitoring factor besides CEA.

Discordance between K-ras mutations in bone marrow micrometastases and the primary tumor in colorectal cancer

PURPOSE

To study bone marrow micrometastases from colorectal cancer patients for the presence of K-ras mutations and to compare their genotype with that of the corresponding primary tumor.

PATIENTS AND METHODS

Bilateral iliac crest aspiration was performed in 51 patients undergoing surgery for colorectal cancer, and bone marrow micrometastases were detected by immunohistochemistry. The presence of K-ras mutations was determined by single-strand conformation polymorphism analysis on both primary tumors and paired bone marrow samples and was confirmed by sequencing.

RESULTS

In six patients with primary tumor mutations, it was possible to amplify a mutated K-ras gene also from the bone marrow sample. In three of those patients the pattern of K-ras mutations differed between both samples, in two patients the mutation was identical between the bone marrow and its primary tumor, and in one patient the same mutation plus a different one were found. Fifteen of 17 K-ras mutations found in primary tumors were located in codon 12, whereas in bone marrow, five of seven mutations were found in codon 13 (P =.003).

CONCLUSION

Our results demonstrate that, at least for K-ras mutations, disseminated epithelial cells are not always clonal with the primary tumor and they question the malignant genotype of bone marrow micrometastases. They also indicate that different tumoral clones may be circulating simultaneously or sequentially in the same patient. Analysis of the type of mutations suggests that cell dissemination might be an early event in colorectal carcinogenesis.

Abnormal hepatic perfusion index predicts recurrence of colorectal carcinoma

OBJECTIVE

The hepatic perfusion index (HPI) is a ratio of the gradient of hepatic arterial to total hepatic blood flow. This study correlated HPI with histopathological indicators of prognosis and disease-free survival following curative resection of colorectal cancer.

PATIENTS AND METHODS

HPI was measured preoperatively by dynamic hepatic scintigraphy in 37 patients with a primary colorectal cancer and no evidence of distant metastases who underwent a curative resection.

RESULTS

Abnormally elevated HPI were detected in 49% of patients and were significantly more frequent in association with locally advanced tumours (T3 and T4) in comparison with early tumours (T1 and T2; 59% vs 20%, respectively; P=0.04). There was no association between abnormal HPI and presence of lymph node metastases or degree of tumour differentiation. The 18-month disease-free survival rate of patients with abnormal HPI was significantly shorter than that of patients with normal HPI (53% vs 100%, respectively; P=0.01), and this was independent of the T category.

CONCLUSION

HPI predicts the risk of recurrent colorectal carcinoma, and this measurement should be included in the panel of prognostic markers in future clinical trials.

Liver colonization by human colon cancer cells is reduced by antisense inhibition of MUC2 mucin synthesis

BACKGROUND & AIMS

Alterations in the production of epithelial mucins have been correlated with advanced tumor stage in the colon, but direct evidence for a role of specific mucin genes in liver metastasis is lacking. The current study was designed to establish more directly the role of MUC2 in colon cancer metastasis.

METHODS

MUC2 levels were manipulated in highly metastatic human colon cancer cells using eukaryotic expression constructs designed to express a portion of MUC2 complementary DNA in antisense orientation. To assess the effect of MUC2 levels on metastatic potential, liver colonization was assessed in athymic mice after splenic-portal inoculation.

RESULTS

Stable integration of the MUC2 antisense construct into metastatic colon cancer cells (LS LiM6) resulted in an 80% reduction in MUC2-specific messenger RNA and a concomitant decrease in MUC2 apomucin protein. This reduction was associated with a 50% reduction in synthesis of mature glucosamine-labeled mucin, almost complete inhibition of secretion of sialyl-LeX and sialyl-Tn antigens, and a 40% decrease in binding of colon cancer cells to E-selectin. Reduction in MUC2 levels was associated with a marked decrease in liver colonization.

CONCLUSIONS

This study provides direct evidence that MUC2 plays an important role in colon cancer metastasis.

Influence of cardiopulmonary bypass surgery on cancer-specific survival rate of patients with colorectal cancer

PURPOSE

There is evidence of a relationship between inflammation and cancer growth and spread. Cardiopulmonary bypass surgery is known to induce a systemic inflammatory response. The aim of this study was to determine whether cardiopulmonary bypass surgery influences the cancer-specific survival rate in patients with colorectal cancer.

METHODS

The Fremantle Hospital database on patients with colorectal cancer (477 patients) was linked to the Western Australian Hospital Morbidity Database System. Patients who had colorectal cancer after having undergone cardiopulmonary bypass surgery (n = 7) were identified. The cancer-specific survival rate for these patients was compared with that for a group of controls derived from the hospital database. Controls were matched for age, gender, tumor location, tumor stage, operative procedure, and adjuvant therapy (n = 26).

RESULTS

The cancer-specific survival rate of the seven patients with colorectal cancer who had undergone cardiopulmonary bypass surgery was significantly lower than that for control patients (5-year survival rate, 34 vs. 71 percent, respectively; P < 0.05; hazard ratio, 2.9; 95 percent confidence interval, 1.5-4.4). Of the two patients in the study group who survived for 18 months, one had liver metastases and the other had local recurrence of a rectal cancer.

CONCLUSION

In patients with colorectal cancer, having undergone cardiopulmonary bypass surgery was associated with a reduced cancer-specific survival rate. Additional studies are required to validate this association and explore the possibility of a causal relationship.