Biology of human colon cancer metastasis

Surgery for pulmonary metastases from colorectal cancer: the importance of prethoracotomy serum carcinoembryonic antigen as an indicator of prognosis

OBJECTIVE

Several investigators have analyzed prognostic factors of surgical treatment for pulmonary metastases from colorectal cancer, but the results remain inconclusive. This study was performed to determine the prognostic implications of the prethoracotomy serum level of carcinoembryonic antigen (CEA) in relation to the postthoracotomy recurrent pattern among patients with this disease.

METHODS

A retrospective analysis of prognostic factors was undertaken in 100 patients who had consecutively undergone initial surgical resection for pulmonary metastases of colorectal origin.

RESULTS

The overall 3- and 5-year survival rates were 62.2% and 49.4%, respectively. Univariate analysis revealed that the prethoracotomy serum CEA level and operative curability were strongly associated with prognosis, while in multivariate analysis, only the prethoracotomy serum CEA level was a significant prognostic indicator. Patients with a high level of prethoracotomy serum CEA more frequently exhibited recurrence in extrathoracic sites, especially in the brain.

CONCLUSION

Before thoracotomy for pulmonary metastases from colorectal cancer, the serum CEA level was the most useful prognostic factor. Patients with elevated serum CEA level should undergo a careful prethoracotomy systemic survey and postthoracotomy follow-up for extrathoracic metastases, in particular brain metastases, and an appropriate combined therapeutic modality should be considered.

Biology of colorectal liver metastases

The elucidation of the interaction of the tumor and its microenvironment has increased surgeons' understanding of the biologic mechanisms mediating metastases formation. The ability to develop effective biologic therapies will depend on understanding the complex interactions among endothelial cells and tumor cells and on the cytokine cross-talk among all cells within a particular tumor at a particular site. Biologic therapies must be targeted to both the site and the tumor. By the time metastases form, most steps in the metastatic cascade have been completed. Therapy to down-regulate or interrupt the last stages of metastases, proliferation, and angiogenesis and mechanisms to disrupt cell survival signals appear to be the most promising areas of investigation.

Pulmonary metastasectomy for 165 patients with colorectal carcinoma: A prognostic assessment

OBJECTIVE

The purpose of this study was to analyze our entire experience with pulmonary resection for metastatic colorectal carcinoma to determine prognostic factors and critically evaluate the potential role of extended metastasectomy.

METHODS

We analyzed the postoperative survival of 165 patients who underwent curative pulmonary surgery at eight institutions in the Kansai region of western Japan (Kansai Clinical Oncology Group) from 1990 to 2000.

RESULTS

Overall survivals at 5 and 10 years were 39.6% and 37.2%, respectively. Cumulative survival of patients who underwent simultaneous bilateral metastasectomy was significantly lower than that of the patients who underwent unilateral metastasectomy or sequential bilateral metastasectomy (P =.048). Five-year survival was 53.6% for patients without hilar or mediastinal lymph node metastasis, versus 6.2% at 4 years for patients with metastases (P <.001). Five-year survival of patients with a prethoracotomy carcinoembryonic antigen level less than 10 ng/mL was 42.7%, versus 15.1% at 4 years for patients with a carcinoembryonic antigen level 10 ng/mL or greater (P <.0001). Twenty-one patients underwent a second or third thoracotomy for recurrent colorectal carcinoma. Overall 5-year survival from the date of the second thoracotomy was 52.1%. The 34.1% 10-year survival for the 26 patients with hepatic metastasis resected before thoracotomy did not differ significantly from that of patients without hepatic metastases (P =.38).

CONCLUSIONS

The status of the hilar or mediastinal lymph nodes and prethoracotomy carcinoembryonic antigen level were significant independent prognostic factors. Patients with pulmonary metastases potentially benefit from pulmonary metastasectomy even when there is a history of solitary liver metastasis. Careful follow-up is warranted, because patients with recurrent pulmonary metastases can undergo repeat thoracotomy with acceptable long-term survival. Simultaneous bilateral metastasectomy confers no survival benefit. Prospective studies may determine the significance of this type of pulmonary metastasectomy.

Soluble adhesion molecules (E-selectin, ICAM-1 and VCAM-1) in breast carcinoma

Adhesion molecules are important in cell-cell and cell-basement membrane interactions. They are intimately involved in inflammatory reactions and a role in tumour progression has been postulated. E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) play a role in cell adhesion to the vascular endothelium, and may have a role in tumour cell dissemination. Soluble forms of these molecules have been described and this study was established to examine these adhesion molecules in patients with breast carcinoma. Serum was obtained from 92 patients with breast carcinoma and 31 age-matched patients with benign breast disease. All samples were obtained prior to surgery. Soluble levels of E-selectin, ICAM-1, and VCAM-1 were significantly elevated in patients with Stage 4 disease compared with controls. (E-selectin 88.6 (47.9) versus 51.4 (18.4) ng/ml; P<0.001: ICAM-1 447 (249) versus 244 (79) ng/ml; P<0.001: VCAM-1 779 (159) versus 552 (135) ng/ml; P<0.001 results expressed on mean (SEM) SD placed above this.). The prognostic value of the adhesion molecules was examined. In patients with Stage 2 disease, elevated VCAM-1 was predictive of decreased survival, even when corrected for T and N status. Adhesion molecules are elevated in patients with advanced disease and elevation in VCAM-1 has prognostic significance in patients with breast carcinoma.

Use of electrolysis as an adjunct to liver resection

BACKGROUND

Patients with hepatic metastases are potentially curable if all the diseased tissue can be resected. Unfortunately, only 10-20 per cent of patients are suitable for curative resection. Electrolysis is a novel non-thermal method of tissue ablation. When used in conjunction with surgery it may increase the number of resectable liver tumours with curative treatment.

METHODS

All patients had been deemed inoperable using currently accepted criteria. Nine patients with hepatic deposits from colorectal carcinoma underwent combined surgical resection and electrolytic ablation of metastases.

RESULTS

The treatment was associated with minimal morbidity. Within the electrolytically treated area seven patients had no radiological evidence of recurrence at a median follow-up of 9 (range 6-43) months; local recurrence was detected in two patients. Six of the nine patients had metastases elsewhere in the liver with four having extrahepatic metastases. Three patients remain tumour free. Three patients died. The median survival was 17 (range 9-24) months from the time of treatment.

DISCUSSION

Electrolysis with resection may confer a disease-free and overall survival benefit. The small size of this initial study precludes statistical analysis, but preliminary results are encouraging.

Glove powder promotes adhesion formation and facilitates tumour cell adhesion and growth

BACKGROUND

The presence of foreign material in the abdominal cavity irritates the peritoneal surface, leading to an inflammatory response. This defensive mechanism can provoke adhesion formation. The same peritoneal defence cascade is thought to play a role in the process of intra-abdominal tumour recurrence. The aim of this study was to evaluate whether glove powder produced peritoneal adhesions in a rat adhesion model and whether it promoted intra-abdominal tumour recurrence in a rat tumour cell adhesion and growth model.

METHODS

A reproducible model that allowed semiquantitative scoring of adhesion formation or tumour load was used in three different groups of rats. One group was treated by intra-abdominal application of powder obtained from starch-powdered gloves, one by application of pure starch and in one group no powder was used.

RESULTS

Application of glove powder or pure starch on minimally and severely traumatized peritoneum gave rise to significantly greater adhesion formation and intra-abdominal tumour load than peritoneal trauma alone (both P < 0.001).

CONCLUSION

Starch-induced peritoneal trauma leads not only to more adhesion formation but also to increased adhesion and growth of tumour cells. Since good powder-free alternatives are available there is no longer any justification for the use of powdered gloves during intra-abdominal surgery.

Orthotopic transplantation model of human gastrointestinal cancer and detection of micrometastases

AIM: To establish a relevant animal model of human gastrointestinal cancer, which can be used for repetitive investigations, so as to improve our understanding and management of carcinogenesis and cancer metastasis.

METHODS: Intact tissues of human colorectal and pancreatic cancers were transplanted in nude mice. The biological characteristics of the original and the corresponding transplanted tumors were investigated by HE staining, PAS staining and immunostaining. The metastases in the livers and lungs of nude mice were investigated by immunostaining with biotinylated mab KL-1 and by RT-PCR using CK20 specific primers.

RESULTS: There were totally 9 of 16 surgical specimens growing in nude mice subcutaneously and/or orthotopically (4 of 6 colorectal and 5 of 10 pancreatic cancer). Tumor cell content of the specimens and freezing of tissue specimens are important factors influencing the growth of transplanted tumor. In the group of fresh tumor tissues with greater than 50% tumor cell content, the success rate of the transplantation was 100% (3 cases of pancreatic cancer and 3 cases of colorectal cancer). The orthotopically transplanted tumors resemble the original tumor morphologically and biologically, including TAA expression such as CEA by immunohistochemistry, and CEA level in the serum of mice. Ki-67 labeling index and the expression of TAA especially K-ras, 17-1A and RA-96, are associated with the potential of tumor growth in nude mice. Micrometastases in the lungs and livers of tumor bearing mice can be detected by immunostaining with biotinylated mab KL-1 and CK20-specific RT-PCR.

CONCLUSION: An orthotopic transplantation model for human colon and pancreatic cancer in nude mice has been set up. We have also established sensitive detection methods with CK-immunohistochemistry and CK20-RT-PCR to study xenotransplanted human cancer and its metastatic cancer cells in the liver and lung of nude mice. This study may be helpful in understanding the mechanism of cancer metastasis and in developing new diagnostic methods and therapeutic strategies for metastases including micrometastases.

Pulmonary resection for metastases from colorectal cancer

BACKGROUND

We reviewed our experience in the surgical treatment of 47 patients with colorectal pulmonary metastases and investigated factors affecting their survival.

METHOD

From September 1986 to December 1999, 47 patients underwent 59 thoracotomies for pulmonary metastases from colorectal cancer.

RESULTS

The median interval between colorectal resection and lung resection (disease-free interval [DFI]) was 33 months. Overall, 5-year survival was 48%. Five-year survival was 51% for patients with solitary metastasis (n = 30), 47% for patients with ipsilateral multiple metastases (n = 11), and 50% for patients with bilateral metastases (n = 6), and there were no significant differences. Five-year survival was 80.8% for 14 patients with DFI of < 2 years and 39.7% for 30 patients with a DFI of > 2 years (p = 0.22). Five-year survival for 11 patients with normal prethoracotomy carcinoembryonic antigen (CEA) levels was 70%, and that for 26 patients with elevated prethoracotomy CEA levels (> 5 ng/mL) was 36% (p < 0.05). Eight patients had extrathoracic disease. The median survival time after pulmonary resection was 18.5 months, and the 5-year survival was 60%. A second resection for recurrent metastases was performed in five patients, and a third resection was done in one patient. All six patients are alive. The median survival of five patients who underwent a second thoracotomy was 22 months (range, 2 to 68 months), and one patient is alive 39 months after the third resection.

CONCLUSION

Pulmonary resection for metastases from colorectal cancer may help prolong survival in selected patients, even with bilateral lesions, recurrent metastasectomy, or extrathoracic disease. Prethoracotomy CEA level was found to be a significant prognostic factor.

Biology of liver metastases

A primary goal of cancer research is an increased understanding of the molecular mechanisms mediating the process of cancer metastasis. Analyses of colon cancer cells (the seeds) and the microenvironment (the soil) have increased our understanding of the biologic mechanisms mediating metastasis formation. Insight into the molecular mechanisms regulating the pathobiology of colon cancer metastasis, as well as a better understanding of the interaction between the metastatic cell and the host environment (including the vasculature), should provide a foundation for new therapeutic approaches. To the clinician, it is readily apparent that by the time metastases form, most steps in the metastatic cascade have completed. Therefore, therapy to down-regulate or interrupt the last stages of metastasis, proliferation and angiogenesis as well as mechanisms to disrupt cell survival signals seems the most promising areas of investigation.

Induction of invasion in vivo of alpha-catenin-positive HCT-8 human colon-cancer cells

Variants from the HCT-8 colon-cancer cell line were implanted s.c. and orthotopically into nude mice. Well-differentiated HCT-8/E11 and HCT-8/E41 cells have a functional E-cadherin-catenin complex and are non-invasive into pre-cultured chick heart fragments in vitro, whereas poorly differentiated HCT-8/E11R1 cells are deficient in alpha-catenin protein and invasive in heart fragments. We investigated whether these differences were maintained in vivo. In contrast with in vitro observations, in vivo the 3 HCT-8 variants behaved very similarly and all formed undifferentiated tumors. The in vivo invasive behavior of HCT-8 cells was site-dependently modulated: HCT-8 cells invaded when injected into the cecum but not when injected s.c. Metastases to the liver or lungs were not observed. The composition and expression of the E-cadherin-catenin complex in nude mouse HCT-8 tumors was the same as in HCT-8 cells in culture on solid substrate. We conclude that the in vivo invasive behavior of HCT-8 cells is not determined by whether alpha-catenin is expressed or not but by as yet unidentified host factors.

Microvasculature of small liver metastases in rats

Neovascularization is important in the development of liver metastasis. We sought to define the origin and fine structure of the blood supply of small experimental liver metastases in rats using an injection replica method. Liver metastases were produced by intraportal inoculation of ascitic fluid containing AH60C hepatoma cells in male Donryu rats (n = 40). Intrahepatic microvasculature was studied by scanning electron microscopy and by stereomicroscopy of microvascular casts produced by perfusion via the abdominal aorta or portal vein 7 days following tumor inoculation. Intrahepatic microvasculature in rats without liver metastases (n = 10) also was studied by scanning electron microscopy. In the normal liver, branches of the hepatic artery typically terminated in the peribiliary plexus and less frequently led to sinusoids and terminal portal veins. In 69 metastatic tumors ranging from 269 to 1875 microm in diameter, arterially perfused metastatic tumors larger than 300 microm showed newly developed neovascularization. Portally perfusion of metastatic tumors did not visualize neovascularization irrespective of tumor size. At the periphery of metastases, tumor vessels disclosed by arterial perfusion most often communicated with the peribiliary plexus and less frequently with terminal arterioles. Metastatic liver tumors as small as 300 microm in diameter receive their main blood supply from the hepatic artery but not from the portal vein, and tumor vessels more often are derived from the arterially filled peribiliary plexus rather than from terminal arterioles.

Taurolidine inhibits tumor cell growth in vitro and in vivo

BACKGROUND

Taurolidine, a derivative of the amino acid taurine, exhibits antiendotoxin, antibacterial, and antiadherence activity. We hypothesized that Taurolidine may inhibit tumor cell growth, both in an in vitro and in vivo setting. Our aim was to examine the effect of Taurolidine on the growth of a rat metastatic colorectal tumor cell line (DHD/K12/TRb) in vitro and in vivo.

METHODS

In the in vitro experiments, DHD/K12/TRb cells were incubated with 5, 10, 15, 25, microg/ml of Taurolidine. Cells incubated in culture medium alone were used as controls. Cell proliferation, cell viability, cell death, and cell apoptosis were measured using commercially available techniques. In the in vivo experiment, BD IX rats were randomized into two groups (n = 10/group). Group A (control) underwent laparotomy and instillation of DHD/K12/TRb tumor cells intraperitoneally followed by phosphate buffered saline (PBS). Group B received Taurolidine (100 mg/kg) instead of PBS. Animals were killed after 24 days and tumor burden assessed by counting the number of tumor nodules in the peritoneal cavity.

RESULTS

Incubation of the tumor cells with Taurolidine resulted in a 4-fold decrease in proliferation rates (25+/-4% vs. 100+/-28% for controls) and a 4-fold increase in cell necrosis as demonstrated by the increase in LDH release (403+/-28% vs. 100+/-26% for controls), at a Taurolidine concentration of 25 microg/ml. A dose-dependent decrease in cell viability was also observed. In the in vivo study, local Taurolidine administration resulted in significant decreases in tumor burden (3+/-1 nodules in Group B animals vs. 649+/-101 nodules in Group A animals).

CONCLUSIONS

Taurolidine inhibits the growth of a rat metastatic colorectal tumor cell line in vitro and in vivo and thus may have potential in the prevention of peritoneal metastases.

Assessment of differential gene expression patterns in human colon cancers

OBJECTIVE

To use a novel genomic approach to determine differential gene expression patterns in colon cancers of different metastatic potential.

SUMMARY BACKGROUND DATA

Colorectal cancer is the third leading cause of cancer deaths in the United States; despite aggressive treatment strategies, the 5-year survival rate for metastatic cancer has not changed in 50 years. The analysis of changes in gene expression patterns associated with metastasis may provide new treatment strategies.

METHODS

Human colon cancer cells KM12C (derived from a Dukes B colon cancer), KML4A (a metastatic variant derived from KM12C), and KM20 (derived from a Dukes D colon cancer) were extracted for RNA. In addition, RNA was extracted from normal colon, primary cancer, and liver metastasis in a patient with metastatic colon cancer. Gene expression patterns for approximately 1,200 human genes were analyzed and compared by cDNA array techniques.

RESULTS

Of the roughly 1,200 genes assessed in the KM cell lines, 9 genes were noted to have a more than threefold change in expression (either increased or decreased) in the more metastatic KML4A and KM20 cells compared with KM12C. Assessment of tissues from a patient with metastatic colon cancer demonstrated a more than threefold change in the expression of 14 genes in the primary cancer and liver metastasis compared with normal mucosa.

CONCLUSIONS

Using cDNA expression array technology, the authors identified genes with expression levels that are altered with metastasis. The ability to analyze and compare the expression patterns of multiple genes simultaneously provides a powerful technique to identify potential molecular targets for novel therapeutic strategies.

E-selectin can mediate the arrest type of adhesion of colon cancer cells under physiological shear flow

The aim of this study was to determine whether colon cancer cells flowing in blood exhibit the same adhesion pattern to the vascular bed as leucocytes using a flow adhesion system. In shear flow conditions, five colon cancer cell lines showed less tethering to E-selectin substrates than polymorphonuclear cells (PMN). However, some of the Colo201 cells formed complete arrest on E-selectin in continuous shear flow which was never observed in PMN cells. Colo201 cells expressed both sialyl Le-x and sialyl Le-a at similar levels in flow cytometry. However, the staining pattern showed marked contrast under the fluorescein microscope. The cell membrane of Colo201 cells was uniformly stained with anti-sialyl Le-a MAb, whereas anti-sialyl Le-x MAb only stained in the patchy areas. Pretreatment of Colo201 cells with anti-sLe-a decreased tethering, while anti-sLe-x significantly inhibited the arrest formation. Our data suggest that E-selectin alone can mediate colon cancer cell lodgement and subsequent metastasis without the contribution of integrin molecules and that the different distribution of E-selectin ligands may affect the adhesion behaviour of colon cancer cells in flow conditions.

Pleuro-pulmonary tumours detected by clinical and chest X-ray analyses in rats transplanted with mesothelioma cells

New strategies for cancer therapy must be developed, especially in severe neoplasms such as malignant pleural mesothelioma. Animal models of cancer, as close as possible to the human situation, are needed to investigate novel therapeutical approaches. Orthotopic transplantation of cancer cells is then relevant and efforts should be made to follow up tumour evolution in animals. In the present study, we developed a method for the orthotopic growth of mesothelioma cells in the pleural cavity of Fischer 344 and nude rats, along with a procedure for clinical survey. Two mesothelioma cell lines, of rat and human origin, were inoculated by transthoracic puncture. Body weight determination and chest X-ray analyses permitted the follow-up of tumour evolution by identifying different stages. Autopsies showed that tumours localized on the whole pleural cavity (diaphragm, parietal pleura), mediastinum and pericardium. Tumour morphology and antigenic characteristics were consistent with those of the inoculated cells and were similar in both types of rats inoculated with the same cell type. These results demonstrate that mesothelioma formation in rats can be followed up by clinical and radiographic survey after gentle intrathoracic inoculation of mesothelioma cells, thus allowing the definition of stages of interest for further experimental trials.

Laminin mediates tethering and spreading of colon cancer cells in physiological shear flow

Under the physiological shear condition, cultured colon cancer cells bound to laminin (LM), but not to fibronectin or vitronectin. Most of the tethered cells did not roll, but arrested immediately and spread within 10-30 min on LM under the continuous presence of shear flow. The tethering of Colo201 was partially inhibited by monoclonal antibodies (mAbs) to alpha6 integrin and a combination of mAbs to beta1 and beta4 integrins, but not by mAb to 67KD laminin receptor. Some Colo201 cells still tethered at 4 degrees C. This suggests that alpha6beta1 and alpha6beta4 integrins participate in Colo201 tethering on LM, although other non-integrin molecules play roles. In contrast, the spread of Colo201 was effectively inhibited by the mAbs to integrin alpha2, alpha6 and beta1 chains. The effect of anti-alpha2 plus anti-alpha6 mAbs was almost equal to anti-beta1, suggesting that Colo201 cells mainly use alpha2beta1 and alpha6beta1 integrins for spreading on LM. When the cells were perfused on subconfluent endothelial cells (HUVEC) cultured on LM, they did not tether on HUVEC but did on coated LM exposed at intercellular gap area. Immunohistochemistry revealed that LM abundantly existed in the cytosol of human portal and hepatic vein endothelial cells. These data suggest that LM can mediate from tethering to spreading of colon cancer cells under the blood flow and plays an essential role in haematogeneous metastasis.

An interaction between human colon carcinoma cells and hepatocytes activates transforming growth factor-beta1 in vitro

We established in vitro heterotypic co-cultures of a human colon carcinoma cell line, HT-29, and a human hepatocyte line, tPH5CH, using transwells to investigate possible interactions between colon carcinoma cells and hepatocytes during the metastatic process. Co-culture, but not HT-29 conditioned medium, inhibited tPH5CH cell proliferation, and this inhibition was blocked by an anti-TGF-beta1 antibody. Significantly more activated TGF-beta1 was released by co-culture than by each cell line cultured alone, whereas there were no significant differences between the total TGF-beta1 released by the individual cultured cell lines and that released by co-culture. These data indicate that an interaction between human colon carcinoma cells and hepatocytes activates TGF-beta1 in vitro.

Interstitial laser coagulation for hepatic tumours

BACKGROUND

The potential role of interstitial laser coagulation (ILC) for patients with irresectable hepatic tumours is currently being investigated. Since its introduction in 1983 it has evolved into an innovative minimally invasive technique.

METHODS

On the basis of a Medline literature search and the authors' experience, the principles, current state and prospects of ILC for hepatic tumours are reviewed.

RESULTS

Animal studies and early clinical studies have shown the safety and feasibility of ILC. The site of interest can be approached at laparoscopy or percutaneously and treatment is easily repeatable. Recent advances include the use of fibres with a cylindrical diffusing light-emitting tip, the length of which is adaptable to tumour diameter, water-cooled fibre systems, simultaneous multiple fibre application, and hepatic inflow occlusion during laser treatment. ILC allows complete destruction of tumours up to 5 cm in diameter. Currently a limitation is the lack of reliable real-time monitoring of laser-induced effects but progress in magnetic resonance imaging techniques should allow accurate temperature measurements to be obtained rapidly during treatment. However, the actual benefit of ILC in terms of patient survival remains to be investigated.

CONCLUSION

In terms of tools and experience, ILC has now been developed sufficiently to study its effect on survival of patients with irresectable hepatic tumours.

Molecular determinants of colon cancer metastasis

Colon cancer metastasis is a tightly regulated process that requires a cancer cell to express genes that allow progression through various distinct steps. Aberrations in gene expression by cancer cells leads to transformation, growth, angiogenesis, invasion, dissemination and survival in the circulation, attachment in the organ of metastasis, and again invasion, growth, and angiogenesis. In addition to the genotype/phenotype of the tumor cell, for a tumor cell to become a clinically relevant metastasis, it must be able to respond appropriately to the environment. This includes being able to utilize growth factors and blood vessels from the organ of metastasis for the benefit of the tumor mass. Understanding the molecular and biologic mechanisms of colon cancer metastasis will allow the development of rationale therapeutic strategies that are more likely to impact the natural history of this disease than current therapies.

Effects of fatty acids on liver metastasis of ACL-15 rat colon cancer cells

The effects of eicosapentaenoic acid [EPA; n-3 polyunsaturated fatty acid (PUFA)], linoleic acid (LA; n-6 PUFA), and palmitic acid (PA; saturated fatty acid) on 1,2-dimethylhydrazine-induced F344 rat colon carcinoma cells (ACL-15) were investigated in vivo and in vitro. The number and size of liver metastatic foci via a superior mesenteric vein injection of ACL-15 cells in F344 rats were significantly inhibited in the EPA-treated group compared with the LA-treated group (p < 0.01); the PA-treated animals and those fed commercial rodent chow (standard diet) demonstrated intermediate values. In a dot immunoblotting assay, vascular cell adhesion molecule 1 expression on ACL-15 cells was downregulated by EPA-ethyl ester treatment and upregulated by LA-ethyl ester treatment compared with the untreated control cells, whereas the expression of matrix metalloproteinase 1 and 2 was not influenced by the fatty acid ethyl esters. In a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, EPA-ethyl ester suppressed ACL-15 cell growth in a schedule-dependent manner, and LA-ethyl ester showed schedule-dependent stimulation. In contrast, PA demonstrated no regulatory effect on cell growth at lower concentrations (< or = 5 mg/ml) but concentration-dependent inhibition at higher concentrations. According to our in vivo cell kinetic study, the difference in tumor growth at the metastatic site was due to different tumor cell proliferation rates; the cell loss rate was not altered. Therefore, the inhibitory effect of liver metastasis on ACL-15 cells by EPA can be explained by a decreased ability of tumor cell adhesion to the capillary bed (low expression of vascular cell adhesion molecule 1) and a lower potential of tumor cell proliferation (low mitotic rate) at the secondary site.

Surgical treatment of hepatic and pulmonary metastases from colorectal cancers

BACKGROUND

Selected patients with double hepatic and pulmonary metastases from colorectal cancer may benefit from operation.

METHODS

From 1970 to 1995, 239 patients underwent operation for resection of pulmonary metastases from colorectal cancer at two French surgical centers. Among these patients, 43 (18%) had previously undergone complete resection of hepatic metastases and constitute the subject of this retrospective study.

RESULTS

The median interval time between hepatic and pulmonary resections was 18 months. Two pneumonectomies, 5 lobectomies, 3 segmentectomies, 6 wedge resections, and 27 metastasectomies were performed. No postoperative mortality was observed. Two patients had major postoperative complications. Seven patients (16%) underwent subsequent pulmonary resection for recurrences. Twenty-one patients were still alive, 14 free of disease. The median survival from pulmonary resection was 19 months and the 5-year probability of survival was 11%. Prethoracotomy carcinoembryonic antigen blood levels and the number of pulmonary resection were found to be significant prognostic factors; the interval time between hepatic and pulmonary resection (> 36 months) was borderline significant (p = 0.06).

CONCLUSIONS

Selected patients with combined hepatic and pulmonary metastases from colorectal cancer should be considered for surgical resection. Patients with normal prethoracotomy carcinoembryonic antigen levels and late metachronous pulmonary metastasis, appear to be the best surgical candidates.

Regulation of protrusion shape and adhesion to the substratum during chemotactic responses of mammalian carcinoma cells

We report here the first direct observation of chemotaxis to EGF by rat mammary carcinoma cells. When exposed to a gradient of EGF diffusing from a micropipette, MTLn3 cells displayed typical ameboid chemotaxis, extending a lamellipod-like protrusion and moving toward the pipette. Using a homogeneous upshift in EGF to model stimulated lamellipod extension (J. E. Segall et al., 1996, Clin. Exp. Metastasis 14, 61-72), we analyzed the relationship between adhesion and chemoattractant-stimulated protrusion. Exposure to EGF led to a rapid remodeling of the adhesive contacts on adherent cells, in synchrony with extension of a flat lamellipod over the substratum. EGF-stimulated lamellipods still extended in the presence of adhesion-blocking peptides or over nonadhesive surfaces. They were, however, slightly shorter and retracted rapidly under those conditions. The major protrusive structure observed on well-spread, adherent cells, after EGF stimulation was a flat broad lamellipod, whether or not in contact with the substratum, while cells in suspension showed transient protrusive activity over the entire cell surface. We conclude that the initial adhesive status of the cell conditions the shape of the outcoming protrusion. Altogether our results suggest that, although adhesive contacts are not necessary for lamellipod extension, they play a role in stabilizing the protrusion as well as in the control of its final shape and amplitude.

Management strategies for colorectal liver metastases--Part I

Colorectal cancer is a common malignancy and the incidence of this disease is increasing. Approximately 50% of patients with colorectal cancer die from recurrent disease following an apparently curative resection of the primary tumour and the liver is the most frequent site of relapse. Although only a small proportion of patients will benefit from resection of liver metastases, this form of treatment offers the only possibility of cure. In selected patients, 5-year survival rates of 25-35% may be achieved following liver resection. A poor prognosis after resection of hepatic metastases is likely when there are more than three metastatic deposits, involved resection margins often as a result of ¿wedge' resections, when there is extrahepatic disease, or when there is nodal involvement at the primary tumour site. Regional hepatic artery infusion chemotherapy may provide palliation and possibly even prolongation of survival for some patients with unresectable metastases. Cytoreductive techniques may also provide palliation in selected patients with hepatic metastases unsuitable for resection; cryotherapy is the most promising of these methods.

Surgery for primary and metastatic colorectal cancer

Carcinoma of the colon and rectum currently ranks as the second leading cause of death from cancer in the United States. Surgery remains the cornerstone of treatment for colorectal cancer but has inherent limitations imposed by the biology and stage of the tumor and its location. Ultimately, 50% of patients who undergo curative resection develop local, regional, or widespread recurrence. These statistics have remained relatively constant over several decades despite improved methods of early diagnosis and surgical treatment but may change as new multimodality treatment regimens are developed and clinically evaluated. This article summarizes the surgical management of colorectal cancer and discusses issues pertaining to postoperative surveillance and the diagnosis and management of local or widespread cancer recurrence.

Butyrate inhibits seeding and growth of colorectal metastases to the liver in mice

BACKGROUND

The short-chain fatty acid butyrate inhibits growth of colorectal carcinoma cells in vitro. Mevalonate, a short-chain fatty acid structurally and metabolically related to butyrate, is important in signal transduction and is essential for cell growth. We investigated butyrate's effects on seeding and growth of colorectal tumor cells metastatic to the liver in vivo and hypothesized that butyrate's antiproliferative effects are associated with inhibition of mevalonate-mediated cell growth.

METHODS

Hepatic metastases were induced by injecting 1 x 10(5) MC-26 (N-methyl-N-nitrosourea-induced murine colorectal carcinoma) cells into the spleen of BALB/c mice. Mice were treated with a continuous intravenous infusion of butyrate (2 gm/kg/day) for 7 days starting 24 hours before tumor cells were injected. Study variables included liver weight and number of hepatic surface metastases. Proliferation studies on MC-26 cells were performed in vitro to examine the effects of butyrate alone or combined with mevalonate or mevastatin (an inhibitor of mevalonate synthesis).

RESULTS

Butyrate reduced seeding and growth of colorectal tumor cells in vivo. Mevalonate diminished butyrate's antiproliferative action in vitro, whereas mevastatin potentiated this effect.

CONCLUSIONS

These studies (1) show that butyrate inhibits seeding and growth of hepatic colorectal metastases in vivo, (2) associate butyrate's antiproliferative effects with inhibition of mevalonate-mediated cell growth, and (3) indicate that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors may have synergistic antiproliferative effects when combined with butyrate.