The role of peptidases in cancer of the rectum and sigmoid colon

Immune-related gene expression signatures in colorectal cancer

The immune system is crucial in regulating colorectal cancer (CRC) tumorigenesis. Identification of immune-related transcriptomic signatures derived from the peripheral blood of patients with CRC would provide insights into CRC pathogenesis, and suggest novel clues to potential immunotherapy strategies for the disease. The present study collected blood samples from 59 patients with CRC and 62 healthy control patients and performed whole blood gene expression profiling using microarray hybridization. Immune-related gene expression signatures for CRC were identified from immune gene datasets, and an algorithmic predictive model was constructed for distinguishing CRC from controls. Model performance was characterized using an area under the receiver operating characteristic curve (ROC AUC). Functional categories for CRC-specific gene expression signatures were determined using gene set enrichment analyses. A Kaplan-Meier plotter survival analysis was also performed for CRC-specific immune genes in order to characterize the association between gene expression and CRC prognosis. The present study identified five CRC-specific immune genes [protein phosphatase 3 regulatory subunit Bα (PPP3R1), amyloid β precursor protein, cathepsin H, proteasome activator subunit 4 and DEAD-Box Helicase 3 X-Linked]. A predictive model based on this five-gene panel showed good discriminatory power (independent test set sensitivity, 83.3%; specificity, 94.7%, accuracy, 89.2%; ROC AUC, 0.96). The candidate genes were involved in pathways associated with ‘adaptive immune responses’, ‘innate immune responses’ and ‘cytokine signaling’. The survival analysis found that a high level of PPP3R1 expression was associated with a poor CRC prognosis. The present study identified five CRC-specific immune genes that were potential diagnostic biomarkers for CRC. The biological function analysis indicated a close association between CRC pathogenesis and the immune system, and may reveal more information about the immunogenic and pathogenic mechanisms driving CRC in the future. Overall, the association between PPP3R1 expression and survival of patients with CRC revealed potential new targets for CRC immunotherapy.

Identification of acute-phase proteins (APP) in circulating immune complexes (CIC) in esophageal cancer patients' sera

The occurrence of increased circulating immune complexes (CIC) in sera of patients with esophageal cancer and their usefulness for diagnosis and prognosis have not been demonstrated. Circulating acute-phase proteins (APP) related to esophageal cancer have been described but without any association with CIC. This is a study to measure CIC, C-reactive protein (CRP), and alpha 1-acidic glycoprotein (AAG) in pretreatment esophageal cancer sera and to analyze the presence of both APP associated with these CIC. Increased CIC levels were found in 57% of sera from esophageal cancer patients; elevated CRP was detected in 87% and AAG in 47%. Western blot analysis showed the presence of CRP and AAG in CIC-derived fractions. We conclude that: (1) CIC, CRP, and AAG are elevated in esophageal cancer sera; (2) they may be considered possible useful clinical parameters in pretreatment esophageal cancer patients; (3) these APPs appear in CIC precipitates and may possibly be involved in their composition.

Cathepsin B, L, and D activities in colorectal carcinomas: relationship with clinico-pathological parameters

Cathepsins, which are secreted by tumour and/or stromal cells, are thought to be involved in the degradative processes of tumour invasion and metastasis. The purpose of our study was to compare the cytosolic content of cathepsin B, L, and D in a series of matched malignant and adjacent normal colorectal tissues. Further we attempted to correlate these different proteinase values to classical clinico-pathological prognostic variables. Cathepsin B, L, and D activities were higher in tumour tissues than in normal mucosa (P < 10(-6), P < 0.004, P < 0.004, respectively) with median tumour/normal ratios of 7.9, 5.9, and 1.4, respectively. We found no difference in cathepsin B, L, and D activities either as a function of gender (except for cathepsin B values), age at time of surgery, tumour site, tumour differentiation, tumour stage (TNM or Astler-Coller staging system) or whether or not we found a mucinous component. Based on our data, cathepsin B seems to be the most discriminant parameter of the three proteinases that we studied, suggesting that cathepsin B expression may be of critical value in the progression of colorectal cancers.

The distribution of matrix metalloproteinases and tissue inhibitor of metalloproteinases in colorectal cancer

Studies suggest that the interplay between matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitor of metalloproteinases (TIMPs), is an important mediator of tumour invasion and metastasis. Using immunohistochemistry, 40 specimens of colorectal cancer were examined for the presence of TIMP-1 and the MMPs, stromelysin, gelatinases A and B and interstitial collagenase. Neither enzyme nor TIMP-1 was detected in histologically normal mucosa. Within malignant tissue, stromelysin and gelatinase A were conspicuously absent in tumour cells but were immunolocalized to the extracellular matrix and for gelatinase A also to peritumoural fibroblast-like cells. Gelatinase B was confined to polymorphonuclear leucocytes. Interstitial collagenase was not identified. TIMP-1 was present in only three of the 40 tumours within the malignant stroma. These observations suggest that the mesenchymal elements of colorectal carcinomas, by acting as a source of MMPs and TIMPs, may modulate tumour invasion.

The distribution of matrix metalloproteinases and tissue inhibitor of metalloproteinases in colorectal cancer

Studies suggest that the interplay between matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitor of metalloproteinases (TIMPs) is an important mediator of tumour invasion and metastasis. Using immunohistochemistry, 40 specimens of colorectal cancer were examined for the presence of TIMP-1 and the MMPs, stromelysin, gelatinases A and B and interstitial collagenase. Neither enzyme nor TIMP-1 was detected in histologically normal mucosa. Within malignant tissue, stromelysin and gelatinase A were conspicuously absent in tumor cells but were immunolocalized to the extracellular matrix and for gelatinase A also to peritumoural fibroblast-like cells. Gelatinase B was confined to polymorphonuclear leucocytes. Interstitial collagenase was not identified. TIMP-1 was present in only three of the 40 tumours within the malignant stroma. These observations suggest that the mesenchymal elements of colorectal carcinomas, by acting as a source of MMPs and TIMPs, may modulate tumour invasion.

Staging and surgery for colorectal cancer

Staging of colorectal cancer has become increasingly important to select groups of patients for limited or more extensive surgery, and for adjuvant radiotherapy and chemotherapy. The main treatment is still surgery, but subgroups may benefit from adjuvant therapy, even accepting additional side effects. Accurate staging is necessary to define different treatment groups. A critical review is given of the present methods of clinicopathological staging.

Peptide and protein drugs: II. Non-parenteral routes of delivery

In this second part of a two-part review, the absorption and delivery of peptide and protein drugs via non-parenteral routes are discussed. Approaches considered include the absorption enhancers, iontophoretic methods, the use of absorption inhibitors and prod rugs.

Association between extent of colonic mucosal sialomucin change and subsequent local recurrence after curative excision of primary colorectal cancer

Two interrelated studies were carried out to determine whether extent of sialomucin change adjacent to a primary colorectal carcinoma predicted local tumour invasiveness and risk of local recurrence. In the first, depth of tumour penetration was correlated with the length of the sialomucin band adjacent to 72 primary colorectal cancers. There was a significant (P less than 0.05) increase in sialomucin band length adjacent to tumours invading adjacent structures compared with those which had not (Mann-Whitney U test), although there was no overall correlation between depth of penetration, Duke's classification or degree of differentiation (Kruskal-Wallis test). A sialomucin band of greater than 3 cm was associated with a 70 per cent probability of adjacent structure (T4) invasion. These observations were then tested prospectively in a second study involving 256 patients to determine whether the presence of a greater than 3 cm sialomucin band could predict local recurrence. Presence of a greater than 3 cm sialomucin band was a significant (x2 = 7.12, d.f. = 1, P less than 0.001) and independent predictor of local but not distant recurrence. In addition both the interval to local recurrence and survival were significantly shorter if a greater than 3 cm sialomucin band was present. However the accuracy of greater than 3 cm sialomucin band as a predictive test for local recurrence was only 70 per cent. The extent of sialomucin adjacent to a primary colorectal cancer does provide a crude assessment of tumour invasiveness and risk of local recurrence.

Correlation between collagenolytic activity and grade of histological differentiation in colorectal tumors

Collagenolytic activity, extracted from 55 tumor and healthy corresponding intestinal control samples, was determined by 3 different assays using soluble type I and fibrillar type I and III collagen, respectively, as substrate. The enzyme extracted from tumor-digested collagen type I reconstituted fibrils and yielded the three-quarter segments characteristic for the action of one of the matrix metalloproteinases: MMP-I or mammalian collagenase. Metal-chelating agents such as EDTA and O-phenanthrolin indeed inhibited this activity. Collagenolytic activities were calculated on the basis of wet weight, total DNA and total extracted protein. Correlations were sought between levels of activity and both clinicopathological stage (Dukes' staging) and grade of histological differentiation. In all the assays applied, significant correlations were found between grade of histological differentiation and collagenolytic activity expressed as the tumor/control ratios: poorly differentiated tumors exhibited a higher tumor/control ratio than well-differentiated tumors. Also, tumors penetrating into the serosa showed a higher tumor/control ratio than tumors invading the muscularis propria only. A relation between collagenolytic activity and clinico-pathological stage was observed only if activities were calculated on a DNA basis. These results confirm a relationship between the histological appearance of a tumor and its enzymatic potential to degrade interstitial collagens.

Value of serum acute-phase reactant proteins and carcinoembryonic antigen in the preoperative staging of colorectal cancer. A multivariate analysis

In 55 patients with benign or malignant neoplasias of the large bowel, serum carcinoembryonic antigen (CEA), C-reactive protein (CRP), alpha 1-antitrypsin (AAT), alpha 1-acid glycoprotein (AAG) levels, and the percentage of serum protein electrophoretic components were measured. Statistical analysis showed significant correlations between serum CEA, CRP, AAG, and AAT levels and the percentage of serum beta-globulins with the stage of the disease. Multivariate discriminant analysis gave a final prognostic model that included serum CEA, CRP, and AAT levels and the percentage of the serum beta-globulins with a significance of P less than 0.000001. The authors conclude that the serum acute-phase protein levels, in combination with serum CEA concentrations, have a definite role in the preoperative staging of large bowel cancer.

Studies on components of the contact phase system in patients with advanced gastrointestinal cancer

The authors have studied components of the contact system in plasma obtained from patients with advanced gastrointestinal cancer. Plasma samples from 118 healthy blood donors served as controls. Plasma prekallikrein (PKK) values, evaluated by chromogenic peptide substrate technique, were significantly decreased in patients with cancer compared with healthy blood donors. High molecular weight kininogen (HMwK) and Hageman factor (FXII) values, assayed by immunochemical techniques, were also decreased in the patients with cancer. The changes of contact factors were most pronounced in patients with liver metastasis. The most striking observation in our study, however, was the elevated inhibitor values in patients with cancer. Alpha-2-macroglobulin (alpha 2-M) and C1 inhibitor (C1INH) values, determined both by functional and immunochemical techniques, were markedly increased in patients with cancer. In conclusion, this study shows that patients with intestinal cancer have reduced values of contact factors and markedly elevated inhibitor values which indicate that development of malignant tumors in the gastrointestinal tract is associated with changes in the contact system of plasma.

Colorectal cancer. The bases for a comprehensive follow-up

The purpose of this article was to review the effectiveness of follow-up in patients with colorectal cancer submitted to curative treatment. A comprehensive follow-up involves rational initial management of the primary tumor, knowledge of prognostic factors, selection of the patient to be followed, determination of the time for follow-up, use of the most appropriate tests for early diagnosis of recurrence, and eventual curative treatment. The updated answers to all these questions are given through an extensive review of the world literature and confronted with the authors' experience of eight years of follow-up in a series of 170 colorectal cancer patients treated for cure. Although the future might be more promising, past world experience suggests only a few patients could be saved. It is concluded that there is no place for incomplete and disperse screening tests, and only comprehensive, intensive, and very well-coordinated follow-up programs should be undertaken if better results are hoped to be achieved.

Plasminogen activators in experimental colorectal neoplasia: a role in the adenoma-carcinoma sequence?

An important step in the transition from adenomatous polyp to invasive carcinoma is the degradation of the epithelial basement membrane. By the generation of plasmin, plasminogen activators may play an important role in regulating the extracellular protease activity required for this event to occur. The production of biofunctional urokinase and of tissue plasminogen activator was therefore investigated in the dimethylhydrazine induced rat model of colorectal neoplasia. Both adenomatous polyps (p values less than 0.001) and colorectal carcinomas (p values less than 0.001) were demonstrated to produce a significant excess of both urokinase and tissue plasminogen activator when compared with macroscopically normal colon. There was, however, no increased production of either enzyme by macroscopically normal preneoplastic colon when compared with control colon. This enhanced capacity of colorectal tumours to produce plasminogen activators and generate plasmin is thus a feature of both the premalignant as well as the malignant phenotype. These enzymes may contribute to the malignant potential of adenomatous polyps and to the invasive capacity of established carcinomas.

Role of urokinase in colorectal neoplasia

The biofunctional activity of the plasminogen activators urokinase and tissue plasminogen activator has been measured in extracts from 50 colorectal carcinomas and 21 adenomas using a bioimmunoassay. Compared with control mucosa urokinase activity was significantly elevated in adenomas (P less than 0.001) and carcinomas, levels being significantly higher in carcinomas (P less than 0.05). In contrast tissue plasminogen activator activity was reduced in adenomas (P less than 0.01) and carcinomas, levels being significantly lower in carcinomas (P less than 0.01). Although enzyme activity did not relate to Dukes' stage or histological grade urokinase activity was higher in carcinomas with venous invasion (n = 17, P less than 0.05), in those with moderate or extensive local spread (n = 27, P less than 0.05) and in cases where a palliative resection only was feasible because of advanced disease (n = 8, P less than 0.05). Urokinase has been implicated in tissue degradation as well as fibrinolysis and may play a role in tumour invasion and metastasis in human colorectal neoplasia.

Mucinous carcinoma of the rectum

We have studied and compared 316 mucinous and 45 signet ring cell carcinomas of the rectum with 413 non-mucinous carcinomas. Mucinous carcinomas were subdivided according to the amount of mucus which was gauged subjectively as either more or less than 75% of the tumour volume. Five year survivals for non-mucinous, mucinous (less than 75%), mucinous (greater than 75%) and signet ring cell carcinoma were 62%, 60%, 53% and 13%. Mucinous carcinomas (less than 75%) were relatively well differentiated and showed an age distribution identical to their non-mucinous counterparts, but differed in their strong association with villous adenoma. Mucinous carcinomas (greater than 75%) were less well differentiated and, like signet ring cell carcinomas, occurred in younger patients and showed no special association with villous adenoma. Clinically important and independent predictive variables were found by the method of multivariate regression analysis to be number of lymph node metastases, extent of spread in continuity, character of invasive margin and peritumoural lymphocytic infiltration. After adjustment for these factors, typing of rectal cancer as mucinous, non-mucinous and signet ring cell gave no additional, clinically useful prognostic information.

Plasminogen activators in human colorectal neoplasia

A crucial step in the transition from adenomatous polyp to invasive colorectal cancer is the degradation of the epithelial basement membrane. Plasminogen activators may play a part in regulating the extracellular protease environment necessary for this to occur. Both functional and antigenic activity of the two principal activators of plasminogen, tissue plasminogen activator and urokinase, were measured in 30 colorectal cancers, matched samples of mucosa, and eight adenomatous polyps. Both polyps (p less than 0.01) and carcinomas (p less than 0.001) had raised urokinase activities compared with normal mucosa, the activity being highest in the carcinomas. Activity of tissue plasminogen activator, however, was diminished in both polyps (p less than 0.01) and carcinomas (p less than 0.001) compared with normal mucosa, the values being lowest in carcinomas. Plasmin generation by urokinase--in contrast with tissue plasminogen activator--is fibrin independent and thus less subject to physiological control.