Immunohistochemical assessment of mitochondrial superoxide dismutase (MnSOD) in colorectal premalignant and malignant lesions

Catalase immunoexpression in colorectal lesions

Introduction

It is generally accepted that the gastrointestinal tract, and especially the colon, is constantly exposed to reactive oxygen species (ROS) that may be responsible for the appearance of genetic mutations. To keep a steady-state control over ROS production-detoxification, organisms have evolved a defensive system. Nevertheless, many reports have described decreased level of antioxidant enzymes, especially catalase (CAT), in cancer tissues.

Aim

In this work we try to assess the immunohistochemical expression of CAT protein in colorectal adenoma and adenocarcinoma samples.

Material and methods

This study was performed on resected specimens obtained from 122 patients who had undergone surgical resection for colorectal cancer, and from 120 patients who had undergone colonoscopy. Paraffin- embedded, 4 µm-thick tissue sections were stained for rabbit polyclonal anti CAT antibody obtained from GeneTex (cat. no. GTX110704).

Results

In adenoma strong immunoexpression was detected mainly in infiltrating mononuclear cells within lamina propria. High expression of CAT was significantly associated with grade of dysplasia (high grade vs. low grade, p = 0.037). In adenocarcinoma samples, the high level of CAT immunoexpression was significantly correlated with histological grade of tumour (G1 vs. G2 vs. G3, p = 0.001) and depth of invasion (T1 vs. T2 vs. T3 vs. T4, p = 0.003).

Conclusions

Development of colorectal cancer is associated with increased expression of CAT in the stage of adenoma and decreased expression in the stage of adenocarcinoma.

Carcinogenesis and Reactive Oxygen Species Signaling: Interaction of the NADPH Oxidase NOX1-5 and Superoxide Dismutase 1-3 Signal Transduction Pathways

SIGNIFICANCE

Reduction/oxidation (redox) balance could be defined as an even distribution of reduction and oxidation complementary processes and their reaction end products. There is a consensus that aberrant levels of reactive oxygen species (ROS), commonly observed in cancer, stimulate primary cell immortalization and progression of carcinogenesis. However, the mechanism how different ROS regulate redox balance is not completely understood. Recent Advances: In the current review, we have summarized the main signaling cascades inducing NADPH oxidase NOX1-5 and superoxide dismutase (SOD) 1-3 expression and their connection to cell proliferation, immortalization, transformation, and CD34+ cell differentiation in thyroid, colon, lung, breast, and hematological cancers.

CRITICAL ISSUES

Interestingly, many of the signaling pathways activating redox enzymes or mediating the effect of ROS are common, such as pathways initiated from G protein-coupled receptors and tyrosine kinase receptors involving protein kinase A, phospholipase C, calcium, and small GTPase signaling molecules.

FUTURE DIRECTIONS

The clarification of interaction of signal transduction pathways could explain how cells regulate redox balance and may even provide means to inhibit the accumulation of harmful levels of ROS in human pathologies.

Oxidative Stress Gene Expression Profile Correlates with Cancer Patient Poor Prognosis: Identification of Crucial Pathways Might Select Novel Therapeutic Approaches

The role of altered redox status and high reactive oxygen species (ROS) is still controversial in cancer development and progression. Intracellular levels of ROS are elevated in cancer cells suggesting a role in cancer initiation and progression; on the contrary, ROS elevated levels may induce programmed cell death and have been associated with cancer suppression. Thus, it is crucial to consider the double-face of ROS, for novel therapeutic strategies targeting redox regulatory mechanisms. In this review, in order to derive cancer-type specific oxidative stress genes' profile and their potential prognostic role, we integrated a publicly available oxidative stress gene signature with patient survival data from the Cancer Genome Atlas database. Overall, we found several genes statistically significant associated with poor prognosis in the examined six tumor types. Among them, FoxM1 and thioredoxin reductase1 expression showed the same pattern in four out of six cancers, suggesting their specific critical role in cancer-related oxidative stress adaptation. Our analysis also unveiled an enriched cellular network, highlighting specific pathways, in which many genes are strictly correlated. Finally, we discussed novel findings on the correlation between oxidative stress and cancer stem cells in order to define those pathways to be prioritized in drug development.