Quantitative cytochemistry of glucose-6-phosphate dehydrogenase in benign and malignant breast tumours

Nanotherapeutics in autophagy: a paradigm shift in cancer treatment

Autophagy is a catabolic process in which an organism responds to its nutrient or metabolic emergencies. It involves the degradation of cytoplasmic proteins and organelles by forming double-membrane vesicles called "autophagosomes." They sequester cargoes, leading them to degradation in the lysosomes. Although autophagy acts as a protective mechanism for maintaining homeostasis through cellular recycling, it is ostensibly a cause of certain cancers, but a cure for others. In other words, insufficient autophagy, due to genetic or cellular dysfunctions, can lead to tumorigenesis. However, many autophagy modulators are developed for cancer therapy. Diverse nanoparticles have been documented to induce autophagy. Also, the highly stable nanoparticles show blockage to autophagic flux. In this review, we revealed a general mechanism by which autophagy can be induced or blocked via nanoparticles as well as several studies recently performed to prove the stated fact. In addition, we have also elucidated the paradoxical roles of autophagy in cancer and how their differential role at different stages of various cancers can affect its treatment outcomes. And finally, we summarize the breakthroughs in cancer disease treatments by using metallic, polymeric, and liposomal nanoparticles as potent autophagy modulators.

Oxygen insensitivity of the histochemical assay of glucose-6-phosphate dehydrogenase activity for the detection of (pre)neoplasm in rat liver

Oxygen insensitivity of the histochemical assay to detect glucose-6-phosphate dehydrogenase (G6PD) activity with NT as tetrazolium salt has been proved to be a powerful tool to discriminate various types of adenocarcinoma from normal tissues. Here we investigated whether this phenomenon can also be applied to differentiate between chemically induced hepatocellular (pre)neoplasms and normal liver tissue in rats. Residual activity (percentage of the amount of final reaction product that is generated in oxygen and that is generated in nitrogen) was 60% in (pre)neoplastic cells and 6% in normal liver parenchymal cells. This means that the oxygen insensitivity test is a useful tool to distinguish (pre)neoplasms from normal rat liver tissue. N-Ethylmaleimide, a blocker of SH groups, did not affect G6PD activity in (pre)neoplastic cells, whereas activity in normal cells was reduced by half. Therefore, the absence of essential SH groups in G6PD in (pre)neoplastic cells is held responsible for the oxygen insensitivity phenomenon. We conclude that oxygen insensitivity of the histochemical assay for G6PD activity is a fast, easy, and cheap tool to diagnose (pre)neoplasms in rat liver. Discrimination is likely to be based on altered properties of the enzyme in (pre)neoplastic cells. (J Histochem Cytochem 49:565-571, 2001)

Oxygen insensitivity of the histochemical assay of glucose-6-phosphate dehydrogenase activity for the discrimination between nonmalignant and malignant cells

We review here the oxygen insensitivity of the histochemical assay of glucose-6-phosphate dehydrogenase (G6PDH) activity to detect cancer cells. This inexpensive and rapid assay can be performed within half an hour. Discrimination between cancerous and noncancerous cells is based on a combination of elevated G6PDH activity, decreased superoxide dismutase (SOD) activity, and decreased lipid peroxidation in cancer cells. The test discriminates between adenomas and carcinomas of the colon with a certainty of >80% and has a high prognostic value for survival of colon cancer patients. Pancreatitis and pancreatic cancer are discriminated with a certainty of 100%. Therefore, the test can be applied by pathologists to provide additional information in difficult cases of diagnosis of cancer and for prognosis.

Changes in glutathione redox cycling and oxidative stress response in the malignant progression of NB2 lymphoma cells

Differential analysis of closely related Nb2-lymphoma cell lines can be used for identification of changes in biochemical properties associated with the malignant progression of certain T-cell cancers. As tumors progress, they tend to show metabolic alterations such as an increased resistance to oxidative stress, a characteristic that may be correlated with changes in intrinsic antioxidant levels (e.g., glutathione) and in activities of associated enzymes such as the glutathione redox pathway. Whether increases in malignancy of Nb2 cells were associated with changes in cellular glutathione levels and activities of glutathione-metabolizing enzymes was addressed. To evaluate this relationship, 3 cell lines, showing increased malignancy, were used: Nb2-U17 (hormone-dependent, non-metastatic), Nb2-11 (hormone-dependent, metastatic), Nb2-SFJCD1 (growth factor-independent, metastatic). Compared to Nb2-U17 and Nb2-11 cells, the highly progressed Nb2-SFJCD1 lymphoma cells maintain low basal glutathione levels. However, the Nb2-SFJCD1 cells display an enhanced capacity to produce glutathione when challenged with an oxidative stress and show a significantly higher resistance to H2O2-induced apoptosis.