Immunohistochemical evaluation of cathepsin D expression in colorectal cancer

Preclinical Evaluation of Cathepsin-Based Fluorescent Imaging System for Cytoreductive Surgery

BACKGROUND

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is a treatment option for peritoneal surface malignancies. The ability to detect microscopic foci of peritoneal metastasis intraoperatively may ensure the completeness of cytoreduction. In this study, we evaluated the suitability of a hand-held cathepsin-based fluorescent imaging system for intraoperative detection of appendiceal and colorectal peritoneal metastasis.

METHODS

Peritoneal tumors and normal peritoneal tissues were collected from patients with appendiceal and colorectal peritoneal metastasis. Expression of different cathepsins (CTS-B, -D, -F, -G, -K, -L, -O, and -S) was determined by quantitative RT-PCR and immunohistochemistry. The hand-held cathepsin-based fluorescent imaging system was used to detect peritoneal xenografts derived from human colon cancer cells (HT29, LoVo and HCT116) in nu/nu mice.

RESULTS

While the expression levels of CTS-B, -D, -L, and -S could be higher in peritoneal tumors than normal peritoneum with a median (range) of 6.1 (2.9-25.8), 2.0 (1.0-15.8), 1.4 (0.8-7.0), and 2.1 (1.6-13.9) folds by quantitative RT-PCR, respectively, CTS-B was consistently the major contributor of the overall cathepsin expression in appendiceal and colonic peritoneal tumors, including adenocarcinomas and low-grade appendiceal mucinous neoplasms. Using peritoneal xenograft mouse models, small barely visible colonic peritoneal tumors (<2.5 mm in maximum diameter) could be detected by the hand-held cathepsin-based fluorescent imaging system.

CONCLUSIONS

Because cathepsin expression is higher in peritoneal tumors than underlying peritoneum, the hand-held cathepsin-based fluorescent imaging system could be useful for intraoperative detection of microscopic peritoneal metastasis during CRS-HIPEC and clinical trial is warranted.

Proteases as prognostic markers in human and canine cancers

The extracellular matrix (ECM) is composed of several types of proteins, which interact and form dynamic networks. These components can modulate cell behaviour and actively influence the growth and differentiation of tissues. ECM is also important in several pathological processes, such as cancer invasion and metastasis, by creating favourable microenvironments. Proteolysis in neoplastic tissues is mediated by proteinases, whose regulation involves complex interactions between neoplastic cells and non-neoplastic stromal cells. In this review, we discuss aspects of proteinase expression and tumor behaviour in humans and dogs. Different classes of proteases are summarized, with special emphasis being placed on molecules that have been shown to correlate with prognosis, reinforcing the need for a better understanding of the regulation of this microenvironment and its influences in tumor progression and metastasis, which should significantly aid the development of improved prognosis and treatment.

Prognostic and Predictive Significance of Stromal Fibroblasts and Macrophages in Colon Cancer

Colon cancer development and malignant progression are driven by genetic and epigenetic alterations in tumor cells and by factors from the tumor microenvironment. Cancer cells become reliant on the activity of specific oncogenes and on prosurvival and proliferative signals they receive from the abnormal environment they create and reside in. Accordingly, the response to anticancer therapy is determined by genetic and epigenetic changes that are intrinsic to tumor cells and by the factors present in the tumor microenvironment. Recent advances in the understanding of the involvement of the tumor microenvironment in tumor progression and therapeutic response are optimizing the application of prognostic and predictive factors in colon cancer. Moreover, new targets in the tumor microenvironment that are amenable to therapeutic intervention have been identified. Because stromal cells are with rare exceptions genetically stable, the tumor microenvironment has emerged as a preferred target for therapeutic drugs. In this review, we discuss the role of stromal fibroblasts and macrophages in colon cancer progression and in the response of colon cancer patients to therapy.

The expression of multiple proteins as prognostic factors in colorectal cancer: cathepsin D, p53, COX-2, epidermal growth factor receptor, C-erbB-2, and Ki-67

BACKGROUND/AIMS

A single gene mutation alone cannot explain the poor prognosis of colorectal cancer. This study aimed to establish a correlation between the expression of six proteins and the prognosis of colorectal cancer patients.

METHODS

Tissue samples were collected from 266 patients who underwent surgery for colorectal cancer at our institution from January 2006 to December 2007. The expression of six proteins were determined using immunohistochemical staining of specimens.

RESULTS

Cathepsin D, p53, COX-2, epidermal growth factor receptor, c-erbB-2, and Ki-67 expression were detected in 38.7%, 60.9%, 37.6%, 35.7%, 30.1%, and 74.4% of the samples, respectively. The expression of cathepsin D was significantly correlated with reduced cancer-free survival (p=0.036) and colorectal cancer-specific survival (p=0.003), but the other expression levels were not. In a multivariate analysis, cathepsin D expression was found to be an independent prognostic factor for poorer colorectal cancer-specific survival (hazard ratio, 8.55; 95% confidence interval, 1.07 to 68.49). Furthermore, patients with tumors expressing four or more of the proteins had a significantly decreased cancer-free survival rate (p=0.006) and colorectal cancer-specific survival rate (p=0.002).

CONCLUSIONS

Patients with cathepsin D positivity had a poorer outcome than patients who were cathepsin D-negative. Thus, cathepsin D may provide an indicator for appropriate intensive follow-up and adjuvant chemotherapy.

Acetate-induced apoptosis in colorectal carcinoma cells involves lysosomal membrane permeabilization and cathepsin D release

Colorectal carcinoma (CRC) is one of the most common causes of cancer-related mortality. Short-chain fatty acids secreted by dietary propionibacteria from the intestine, such as acetate, induce apoptosis in CRC cells and may therefore be relevant in CRC prevention and therapy. We previously reported that acetic acid-induced apoptosis in Saccharomyces cerevisiae cells involves partial vacuole permeabilization and release of Pep4p, the yeast cathepsin D (CatD), which has a protective role in this process. In cancer cells, lysosomes have emerged as key players in apoptosis through selective lysosomal membrane permeabilization (LMP) and release of cathepsins. However, the role of CatD in CRC survival is controversial and has not been assessed in response to acetate. We aimed to ascertain whether LMP and CatD are involved in acetate-induced apoptosis in CRC cells. We showed that acetate per se inhibits proliferation and induces apoptosis. More importantly, we uncovered that acetate triggers LMP and CatD release to the cytosol. Pepstatin A (a CatD inhibitor) but not E64d (a cathepsin B and L inhibitor) increased acetate-induced apoptosis of CRC cells, suggesting that CatD has a protective role in this process. Our data indicate that acetate induces LMP and subsequent release of CatD in CRC cells undergoing apoptosis, and suggest exploiting novel strategies using acetate as a prevention/therapeutic agent in CRC, through simultaneous treatment with CatD inhibitors.

Cathepsin D Expression in Colorectal Cancer: From Proteomic Discovery through Validation Using Western Blotting, Immunohistochemistry, and Tissue Microarrays

Despite recent advances in surgical techniques and therapeutic treatments, survival from colorectal cancer (CRC) remains disappointing with some 40–50% of newly diagnosed patients ultimately dying of metastatic disease. Current staging by light microscopy alone is not sufficiently predictive of prognosis and would benefit from additional support from biomarkers in order to stratify patients appropriately for adjuvant therapy. We have identified that cathepsin D expression was significantly greater in cells from invasive front (IF) area and liver metastasis (LM) than those from main tumour body (MTB). Cathepsin D expression was subsequently examined by immunohistochemistry in tissue microarrays from 119 patients with CRC. Strong expression in tumour cells at the IF did not correlate significantly with any clinico-pathological parameters examined or patient survival. However, cathepsin D expression in cells from the MTB was highly elevated in late stage CRC and showed significant correlation with subsequent distant metastasis and shorter cancer-specific survival. We also found that macrophages surrounding tumour cells stained strongly for cathepsin D but there was no significant correlation found between cathepsin D in macrophages at IF and MTB of CRC patient with the clinic-pathological parameters examined.

The cathepsin family and their role in colorectal cancer

Cathepsins are a class of globular proteases, initially described as intracellular peptide hydrolases, although several cathepsins also have extracellular functions. Cathepsins B, C, F, H, L, K, O, S, V, W, and X are cysteine proteases of the papain family, and represent the largest and best-known class of the cathepsins. Cathepsin G is a serine carboxypeptidases, and cathepsins D and E are aspartic proteases. Cathepsins are synthesized as inactive proenzymes and processed to become mature and active enzymes. Endogenous protein inhibitors, such as cystatins and some serpins, inhibit active enzymes. As primarily lysosomal proteases, cathepsins play important roles in proteolysis during physiological processes, as well as in several diseases. On the basis of their ability to degrade extracellular matrix proteins, cathepsins have been implicated to play a role in invasion and metastasis of colorectal cancer. In the present review, the role of cathepsins in the disease process of colorectal cancers and the correlation of cathepsin expression and activity with clinicopathological features is discussed. Furthermore, we give an overview of the recent developments of cathepsins in animal models and in in vitro experiments of colorectal disease, and provide information on inhibitors of cathepsins as possible therapeutics.

Is there a genetic signature for liver metastasis in colorectal cancer?

Even though liver metastasis accounts for the vast majority of cancer deaths in patients with colorectal cancer (CRC), fundamental questions about the molecular and cellular mechanisms of liver metastasis still remain unanswered. Determination of gene expression profiles by microarray technology has improved our knowledge of CRC molecular pathways. However, defined gene signatures are highly variable among studies. Expression profiles and molecular markers have been specifically linked to liver metastases mechanistic paths in CRC. However, to date, none of the identified signatures or molecular markers has been successfully validated as a diagnostic or prognostic tool applicable to routine clinical practice. To obtain a genetic signature for liver metastasis in CRC, measures to improve reproducibility, to increase consistency, and to validate results need to be implemented. Alternatives to expression profiling with microarray technology are continuing to be used. In the recent past, many genes codifying for proteins that are directly or indirectly involved in adhesion, invasion, angiogenesis, survival and cell growth have been linked to mechanisms of liver metastases in CRC.

Prognostic significance of matrix metalloproteinase-2, cathepsin D, and tenascin-C expression in colorectal carcinoma

Matrix metalloproteinase-2 (MMP-2) and cathepsin D (CD) play a significant role in degrading the components of basement membrane and extracellular matrix (ECM), whereas tenascin-C (TN-C) is a glycoprotein of the ECM related to cell adhesion and detachment. These proteins have been implicated in tumor invasion and metastasis. Therefore, we aimed at investigating the prognostic significance of MMP-2, CD, and TN-C expressions in primary colorectal cancer. Overall, 112 colorectal adenocarcinomas were included in the present study. MMP-2, CD, and TN-C expressions were evaluated by immunohistochemistry and correlated with clinicopathologic prognostic parameters and survival. Diffuse stromal TN-C immunostaining was found to be significantly correlated with advanced stage and shorter survival time (p = 0.002 and 0.02, respectively). MMP-2 expression was found to correlate with lymph vessel invasion (p = 0.006) and stage (p = 0.03). CD expression was related to depth of invasion (p = 0.005). No significant relationship was found between survival and MMP-2 and CD expression (p > 0.05). In multivariate analysis, stage and vascular invasion were independent prognostic factors, whereas TN-C did not retain a clear independent relationship to survival (p > 0.05). Our findings suggest that TN-C expression may be a potential prognostic marker in colorectal carcinoma. However, MMP-2 and CD do not appear to be significant indicators of survival.

Tenascin C and cathepsin d expression in adipocytic tumors: an immunohistochemical investigation of 43 cases

Cathepsin D (CatD) and tenascin C (Tn-C) have been implicated in invasion and metastasis of carcinomas. However, little is known about CatD and Tn-C distribution in mesenchymal tumors. Therefore, we aimed to investigate the expression of Tn-C and CatD in adipocytic tumors. Tn-C and CatD expressions in 27 lipomas, 5 atypical lipomatous tumor/well-differentiated liposarcomas (ALT/WDLS) and 11 liposarcomas (LS) were evaluated by immunohistochemistry and scored semiquantitatively. CatD expression was higher in ALT/WDLS than in lipomas (p<0.001), and higher in LS than in ALT/WDLS (p=0.009). Stromal Tn-C expression was higher in ALT/WDLS than in lipomas (p=0.02), but no difference was observed between ALT/WDLS and LS (p>0.05). These results indicate that Tn-C and CatD may be markers of locally aggressive or malignant behavior in adipocytic tumors.

Lysosomes in cell death

For many years apoptosis research has focused on caspases and their putative role as sole executioners of programmed cell death. Accumulating information now suggests that lysosomal cathepsins are also pivotally involved in this process, especially in pathological conditions. In particular, the role of lysosomes and lysosomal enzymes in initiation and execution of the apoptotic program has become clear in several models, to the point that the existence of a 'lysosomal pathway of apoptosis' is now generally accepted. This pathway of apoptosis can be activated by death receptors, lipid mediators, and photodamage. Lysosomal proteases can be released from the lysosomes into the cytosol, where they contribute to the apoptotic cascade upstream of mitochondria. This review focuses on the players and the molecular mechanisms involved in the lysosomal pathway of apoptosis as well as on the importance of this pathway in development and pathology.

Immunohistochemical evaluation of tissue-specific proteolytic enzymes in adenomas containing foci of early carcinoma: correlations with cathepsin D expression and other malignant features

BACKGROUND

Cathepsin D (CD) is an aspartyl lysosomal protease, and the prognostic value of CD expression has been studied in a variety of tumors, however, its role in early adenocarcinomas remains unclear.

AIM OF THE STUDY

We evaluated the expression of CD in a series of colorectal adenomas with severe dysplasia containing foci of early carcinoma and compared the results to several histopathological and immunohistochemical features.

METHODS

Adenomas were obtained by endoscopic polypectomy from 33 patients. Twenty-four of the 33 adenomas contained well-differentiated adenocarcinomas and nine adenomas contained moderately differentiated adenocarcinomas.

RESULTS

Positive CD expressions were observed in 25% of well-differentiated adenocarcinomas and in 66.7% of moderately differentiated adenocarcinomas (p < 0.05). Of the 12 adenocarcinomas with positive CD expression, four had positive CD expression in their adenomas (p < 0.01), 6 showed positive Ki-67 expression in their adenomas (NS), and 10 had positive p53 expression in their adenomas (p < 0.05). No significant association was seen between the level of CD expression and adenoma size.

CONCLUSIONS

The expression of CD in adenocarcinoma correlated significantly with differentiation, and with the levels of CD and p53 expression in the adenomas of the polyp.

Cathepsin D expression in colorectal adenocarcinomas and adenomas

The aim of this study was to investigate the role of cathepsin D in colorectal cancer. For this purpose cathepsin D expression was evaluated by means of immunohistochemistry in stromal and tumor cells of 31 colorectal carcinomas and 29 adenomas. Cytoplasmic cathepsin D expression of tumor cells was present in 90.3% of the carcinoma cases and various degrees of stromal cell cathepsin D expression were present in all cases. In the adenomas, the epithelial cells and stromal cells expressed cathepsin D in 68.96% and 96.55% of cases, respectively. The staining intensity was always weaker in the adenomas. When the stromal and tumor cell cathepsin D expression in the adenocarcinoma and adenoma cases were compared, a statistically significant difference was observed in the staining of stromal cells. Furthermore, stromal cathepsin D expression in the adenocarcinomas was related to tumor stage when the carcinomas were divided into low and high stage. Cathepsin D expression in stromal cells may be an important indicator of poor prognosis in colorectal adenocarcinomas.

Immunohistochemical localization of cathepsin D in colorectal tumors

PURPOSE

Although it has been suggested that cathepsin D, a lysosomal protease, is involved in tumor invasion and metastasis in human colorectal cancers, conflicting studies have also been reported recently. In addition, this issue has been only rarely studied in human colorectal tumors by use of immunohistochemical methods. The aim of the study presented here was to clarify not only the correlation between cathepsin D expression and tumor invasion or metastasis but also the correlation between the intracellular immunostaining pattern of cathepsin D and tumor invasion and metastasis in human colorectal tumors.

METHODS

Thirty-four primary colorectal adenocarcinomas and 24 adenomas were immunostained by use of an anticathepsin D antibody. Both the incidence and the immunostaining patterns of cathepsin D were investigated in all tissue samples.

RESULTS

Three different immunostaining patterns, i.e., supranuclear, basal, and diffuse, were observed in samples containing cathepsin D. Although the incidence of cathepsin D-positive carcinomas was not correlated with tumor progression, invasion, or metastasis, the immunostaining pattern was significantly correlated with lymphatic invasion.

CONCLUSIONS

The results of this study suggest that abnormal cathepsin D immunostaining patterns (basal or diffuse) can be used to predict a potential for lymphatic invasion in colorectal carcinoma.

Unraveling the role of proteases in cancer

Investigators have been studying the expression and activity of proteases in the final steps of tumor progression, invasion and metastasis, for the past 30 years. Recent studies, however, indicate that proteases are involved earlier in progression, e.g., in tumor growth both at the primary and metastatic sites. Extracellular proteases may co-operatively influence matrix degradation and tumor cell invasion through proteolytic cascades, with individual proteases having distinct roles in tumor growth, invasion, migration and angiogenesis. In this review, we use cathepsin B as an example to examine the involvement of proteases in tumor progression and metastasis. We discuss the effect of interactions among tumor cells, stromal cells, and the extracellular matrix on the regulation of protease expression. Further elucidation of the role of proteases in cancer will allow us to design more effective inhibitors and novel protease-based drugs for clinical use.

Cell surface molecules and their prognostic values in assessing colorectal carcinomas

OBJECTIVE

Carcinomas of the colon and rectum are the third leading cause of cancer-related deaths. Although advances in the surgical treatment of primary colorectal cancers have lead to improvements in patient survival at early tumor stages, treatment of more progressive cancers has not resulted in dramatic improvements in patient survival. However, the selection of patient subgroups based on their prognosis and other characteristics could result in improved outcomes from adjuvant therapies in patients with Dukes B and C carcinomas.

METHODS

The authors reviewed the available data on the value of cell surface molecules in assessing the prognosis of colorectal carcinomas, paying specific attention to the evaluation of statistical analysis and multivariate procedures.

RESULTS

Cell surface molecules have been identified on colorectal carcinoma cells whose expression appears to be related to malignant transformation, tumor progression, or patient prognosis. Among these cell surface molecules, various cell adhesion molecules, growth factor receptors, proteinases, and their receptors and inhibitors have been identified as potentially useful prognostic markers.

CONCLUSIONS

Although data exist on the prognostic values of certain cell surface markers, the use of multivariate analysis for the identification of valuable prognostic factors remains uncommon. Using reproducible and standardized multivariate analysis procedures, new tumor markers should be carefully examined for their biologic and prognostic relevance before being considered as potentially useful in the management of colorectal cancers.