Intermittent Hypoxia Mediates Cancer Development and Progression Through HIF-1 and miRNA Regulation

INTRODUCTION

There is still a debate for the link between obstructive sleep apnoea (OSA) and cancer. The mechanisms underlying this causality are poorly understood. Several miRNAs are involved in cancer development and progression with expression being influenced by hypoxia. The aims of this work were (i) to compare miRNAs expression in controls versus patients affected by OSA without or with cancer (ONCO-OSA) and (ii) in colorectal cancer cells exposed to intermittent hypoxia (IH), to evaluate miRNAs impact on tumor progression in vitro.

METHODS

We detected miRNAs by qRT-PCR in patients' sera and in CaCo2 cells exposed to 2-32h of IH with or without acriflavine (ACF), a HIF-1 inhibitor. Viability and transwell invasion test were applied to investigate the proliferation and migration of CaCo2 exposed to IH and treated with miRNA inhibitors or acriflavine. HIF-1α activity was evaluated in CaCo2 cells after IH.

RESULTS

The levels of miR-21, miR-26a and miR-210 increased in OSA and ONCO-OSA patients compared to controls. MiR-23b increased in ONCO-OSA patients, and miR-27b and miR-145 increased in OSA but not ONCO-OSA patients. MiR-21, miR-26a, miR-23b and miR-210 increased in cells after IH. IH stimulated cell proliferation and migration. This effect was reduced after either miRNA inhibition or acriflavine treatment. MiRNA inhibition reduces HIF-1α gene expression. Conversely, acriflavine reduced the expression of these miRNAs.

CONCLUSIONS

We identified a signature of miRNAs, induced by the IH environment. They could be implicated in cancer development and progression through a regulatory loop involving HIF-1.

Comparison of Virosome vs. Liposome as drug delivery vehicle using HepG2 and CaCo2 cell lines

AIM

The present work involves encapsulation of herbal drug nanocurcumin into the virosomes and compared with a liposome in terms of their in vitro anti-proliferative, anti-inflammatory, and anti-migratory efficacy.

METHODS

The anti-proliferative, anti-inflammatory, and anti-migratory efficacy of virosome and liposome were compared in HepG2 and CaCo2 cells by using MTT, Nitric oxide scavenging, and Wound healing assay, respectively.

RESULTS

Size of the optimised NC-Virosome and NC-Liposome was 70.06 ± 1.63 and 265.80 ± 1.64 nm, respectively. The prepared NC-Virosome can be stored at -4 °C up to six months. The drug encapsulation efficiency of NC-Virosome and NC-Liposome was found to be 84.66 ± 1.67 and 62.15 ± 1.75% (w/w). The evaluated minimum inhibitory concentration (IC50 value) for NC-Virosome was 102.7 μg/ml and 108.1 μg/ml, while NC-Liposome showed 129.2 μg/ml and 160.1 μg/ml for HepG2 and CaCo2 cells, respectively. Morphological examination depicts detachment of the cells from substratum after exposure to NC-Virosome for 48 h.

CONCLUSION

The prepared NC-Virosome provides remarkable in vitro efficacy in both the cell lines with site-specific drug-targeting potential as compared to the liposome, results proved its potential as a drug delivery vehicle for future therapy with reduced toxicity.

The Detergent Effect of Mesalazine Interferes with Phosphatidylcholine Binding to Mucin 2

Objectives

Therapeutically applied delayed-release phosphatidylcholine (PC) revealed mucosa protection and clinical improvement of ulcerative colitis. However, a recent trial with simultaneous application of delayed-release PC and mesalazine showed lack of efficacy. It is hypothesized that mesalazine acts as detergent to prohibit PC integration into mucus as target compartment, thus preventing topical mucus protection.

Methods

In vitro PC-binding studies with mucin 2 and intestinally differentiated CaCo2 cells as well as outcome analysis of a therapeutic trial with delayed-release PC and additional mesalazine.

Results

Choline-containing phospholipids, in particular PC, bind to mucin 2 as main scaffold protein of intestinal mucus to establish a hydrophobic barrier towards microbiota in the intestinal lumen. PC also binds to the apical surface of polarized CaCo2 cells with membrane-anchored mucin 3. Mesalazine removes mucin-bound PC and, thus, reduces transepithelial resistance. A post hoc analysis of patients from a previous multicenter phase IIB trial with delayed-release PC revealed that those without mesalazine showed a PC dose-dependent outcome with regard to achievement of partial and complete remission (p < 0.05 for 1.6 and 3.2 g PC daily) whereas those treated simultaneously with mesalazine showed no PC dose dependency.

Conclusion

Mesalazine solubilizes PC and, thus, prevents the protective action of therapeutically applied delayed-release PC within mucus.

The overall fatty acid absorption controlled by basolateral chylomicron excretion under regulation of p-JNK1

Suppression of fatty acid absorption is one goal to fight obesity. However, the responsible molecular mechanism is poorly understood. Aim of the present study was the search for the key regulator of the overall fatty acid absorption mechanism and its pharmaceutical modulation. As experimental tool we employed the polarized human intestinal tumor derived cell line CaCo2. Here we showed that influx of fatty acids is mediated by an apical heterotetrameric plasma membrane protein complex of which the calcium-independent membrane phospholipase A₂ (iPLA₂ß) is one constituent. The newly synthesized bile acid-phospholipid conjugate ursodeoxycholate-lysophosphatidylethanolamide (UDCA-LPE) blocked iPLA₂ß, which structurally disrupted the fatty acid-uptake complex. Furthermore, the inhibition of iPLA₂ß lead to reduction of cytosolic lysophosphatidylcholine (LPC) production which suppressed p-JNK1, as a central regulator of metabolism. In a concerted action low p-JNK1 levels prohibited synthesis of the members of the fatty acid uptake complex as well as of apolipoprotein B and the connected members of the basolateral vesicular chylomicron excretion machinery, thereby inhibiting cellular lipid excretion. The basolateral chylomicron release was shown to determine the overall fatty acid-absorption capacity as rate limiting step, whereas apical uptake replenishes the cellular stores, enabling continuous transcellular movement of fatty acids. In conclusion, the UDCA-LPE mediated inhibition of p-JNK1 represents a powerful tool to control intestinal absorption of fatty acids and, thus may be employed as a drug to treat obesity.