Silencing of the Menkes copper-transporting ATPase (Atp7a) gene increases cyclin D1 protein expression and impairs proliferation of rat intestinal epithelial (IEC-6) cells

Copper in tumors and the use of copper-based compounds in cancer treatment

Copper homeostasis is strictly regulated by protein transporters and chaperones, to allow its correct distribution and avoid uncontrolled redox reactions. Several studies address copper as involved in cancer development and spreading (epithelial to mesenchymal transition, angiogenesis). However, being endogenous and displaying a tremendous potential to generate free radicals, copper is a perfect candidate, once opportunely complexed, to be used as a drug in cancer therapy with low adverse effects. Copper ions can be modulated by the organic counterpart, after complexed to their metalcore, either in redox potential or geometry and consequently reactivity. During the last four decades, many copper complexes were studied regarding their reactivity toward cancer cells, and many of them could be a drug choice for phase II and III in cancer therapy. Also, there is promising evidence of using ⁶⁴Cu in nanoparticles as radiopharmaceuticals for both positron emission tomography (PET) imaging and treatment of hypoxic tumors. However, few compounds have gone beyond testing in animal models, and none of them got the status of a drug for cancer chemotherapy. The main challenge is their solubility in physiological buffers and their different and non-predictable mechanism of action. Moreover, it is difficult to rationalize a structure-based activity for drug design and delivery. In this review, we describe the role of copper in cancer, the effects of copper-complexes on tumor cell death mechanisms, and point to the new copper complexes applicable as drugs, suggesting that they may represent at least one component of a multi-action combination in cancer therapy.

Investigation of the influence of high glucose on molecular and genetic responses: an in vitro study using a human intestine model

Background

Dietary glucose consumption has increased worldwide. Long-term high glucose intake contributes to the development of obesity and type 2 diabetes mellitus (T2DM). Obese people tend to eat glucose-containing foods, which can lead to an addiction to glucose, increased glucose levels in the blood and intestine lumen, and exposure of intestinal enterocytes to high dietary glucose. Recent studies have documented a role for enterocytes in glucose sensing. However, the molecular and genetic relationship between high glucose levels and intestinal enterocytes has not been determined. We aimed to identify relevant target genes and molecular pathways regulated by high glucose in a well-established in vitro epithelial cell culture model of the human intestinal system (Caco-2 cells).

Methods

Cells were grown in a medium containing 5.5 and 25 mM glucose in a bicameral culture system for 21 days to mimic the human intestine. Transepithelial electrical resistance was used to control monolayer formation and polarization of the cells. Total RNA was isolated, and genome-wide mRNA expression profiles were determined. Molecular pathways were analyzed using the DAVID bioinformatics program. Gene expression levels were confirmed by quantitative reverse transcription polymerase chain reaction (RT-qPCR).

Results

Microarray gene expression data demonstrated that 679 genes (297 upregulated, 382 downregulated) were affected by high glucose treatment. Bioinformatics analysis indicated that intracellular protein export (p = 0.0069) and ubiquitin-mediated proteolysis (p = 0.024) pathways were induced, whereas glycolysis/gluconeogenesis (p < 0.0001), pentose phosphate (p = 0.0043), and fructose-mannose metabolism (p = 0.013) pathways were downregulated, in response to high glucose. Microarray analysis of gene expression showed that high glucose significantly induced mRNA expression levels of thioredoxin-interacting protein (TXNIP, p = 0.0001) and lipocalin 15 (LCN15, p = 0.0016) and reduced those of ATP-binding cassette, sub-family A member 1 (ABCA1, p = 0.0004), and iroquois homeobox 3 (IRX3, p = 0.0001).

Conclusions

To our knowledge, this is the first investigation of high glucose-regulated molecular responses in an intestinal enterocyte model. Our findings identify new target genes that may be important in the intestinal glucose absorption and metabolism during high glucose consumption.

Counteract of bone marrow of blotchy mice against the increases of plasma copper levels induced by high-fat diets in LDLR-/- mice

BACKGROUND

Bone marrow of blotchy mouse (blotchy marrow) reflects the function of transmembrane domain and relevant intramembrane sites of ATP7A in myeloid cells. By chronic infusion of angiotensin II, we previously found that blotchy marrow plays a minor role in regulating plasma copper. Moreover, the recipients of blotchy marrow presented a moderate reduction of plasma lipids and inflammatory mediator production. Little is known about whether these changes are a specific response to angiotensin II or reveal a more general role of ATP7A.

OBJECTIVE AND DESIGN

We investigated if blotchy marrow reduces plasma lipids and inflammatory mediators induced by high-fat diets. To test this hypothesis, blotchy and control marrows were reconstituted to the recipient mice (irradiated male LDLR-/- mice), followed by high-fat-diet feeding for 4 months. At the end points, plasma metals (copper, zinc and iron), lipid profiling (cholesterol, triglyceride, phospholipids and lipoprotein) and six inflammatory mediators (lymphotacin, MCP3, MCP5, TIMP1, VEGF-A and IP-10) were measured. Parallel experiments were performed using male LDLR-/- mice fed either high-fat diets or chow diets for 4 months.

RESULTS

In addition to hyperlipidemia and low-grade inflammation, high-fat diets selectively increased plasma copper concentration compared to chow diets in LDLR-/- mice. After high-fat-diet feeding, the recipients with blotchy marrow showed a decrease in plasma copper (p < 0.01) and an increase in plasma iron (p < 0.05). The recipients with blotchy marrow also presented decreases in cholesterol (p < 0.01) and phospholipids (p < 0.05) in plasma. Surprisingly, plasma levels of MCP3 (p < 0.05), MCP5 (p < 0.05), TIMP1 (p < 0.01), VEGF-A (p < 0.01) and IP-10 (p < 0.01) were significantly increased in the recipients with blotchy marrow compared to controls; the increased levels of MCP3, MCP5 and TIMP1 were more than 50%.

CONCLUSION

Our studies showed that blotchy marrow counteracts the increased copper levels induced by high-fat diets, indicating that circulating myeloid cells can regulate blood copper levels via ATP7A. Moreover, transplantation of blotchy marrow followed by high-fat diets leads to a decrease in lipid profile and an increase in inflammatory mediator production. Overall, blotchy marrow mediates divergent responses to angiotensin II and high-fat diets in vivo.