RNA interference-mediated silencing of aquaporin (AQP)-5 hinders angiogenesis of colorectal tumor by suppressing the production of vascular endothelial growth factor

Aquaporin-5 Dynamic Regulation

Aquaporin-5 (AQP5), belonging to the aquaporins (AQPs) family of transmembrane water channels, facilitates osmotically driven water flux across biological membranes and the movement of hydrogen peroxide and CO₂. Various mechanisms have been shown to dynamically regulate AQP5 expression, trafficking, and function. Besides fulfilling its primary water permeability function, AQP5 has been shown to regulate downstream effectors playing roles in various cellular processes. This review provides a comprehensive overview of the current knowledge of the upstream and downstream effectors of AQP5 to gain an in-depth understanding of the physiological and pathophysiological processes involving AQP5.

Aquaporins in Reproductive System

AQP0-12, a total of 13 aquaporins are expressed in the mammalian reproductive system. These aquaporins mediate the transport of water and small solutes across biofilms for maintaining reproductive tract water balance and germ cell water homeostasis. These aquaporins play important roles in the regulation of sperm and egg cell production, maturation, and fertilization processes. Impaired AQP function may lead to diminished male and female fertility. This review focuses on the distribution, function, and regulation of AQPs throughout the male and female reproductive organs and tracts. Their correlation with reproductive success, revealing recent advances in the physiological and pathophysiological roles of aquaporins in the reproductive system.

Aquaporin-6 May Increase the Resistance to Oxidative Stress of Malignant Pleural Mesothelioma Cells

Malignant pleural mesothelioma (MPM) is an aggressive cancer of the pleural surface and is associated with previous asbestos exposure. The chemotherapy drug is one of the main treatments, but the median survival ranges from 8 to 14 months from diagnosis. The redox homeostasis of tumor cells should be carefully considered since elevated levels of ROS favor cancer cell progression (proliferation and migration), while a further elevation leads to ferroptosis. This study aims to analyze the functioning/role of aquaporins (AQPs) as a hydrogen peroxide (H₂O₂) channel in epithelial and biphasic MPM cell lines, as well as their possible involvement in chemotherapy drug resistance. Results show that AQP-3, -5, -6, -9, and -11 were expressed at mRNA and protein levels. AQP-6 was localized in the plasma membrane and intracellular structures. Compared to normal mesothelial cells, the water permeability of mesothelioma cells is not reduced by exogenous oxidative stress, but it is considerably increased by heat stress, making these cells resistant to ferroptosis. Functional experiments performed in mesothelioma cells silenced for aquaporin-6 revealed that it is responsible, at least in part, for the increase in H₂O₂ efflux caused by heat stress. Moreover, mesothelioma cells knocked down for AQP-6 showed a reduced proliferation compared to mock cells. Current findings suggest the major role of AQP-6 in providing mesothelioma cells with the ability to resist oxidative stress that underlies their resistance to chemotherapy drugs.

Targeting ion channels for the treatment of lung cancer

Lung cancer is caused by several environmental and genetic variables and is globally associated with elevated morbidity and mortality. Among these variables, membrane-bound ion channels have a key role in regulating multiple signaling pathways in tumor cells and dysregulation of ion channel expression and function is closely related to proliferation, migration, and metastasis of lung cancer. This work reviews and summarizes current knowledge about the role of ion channels in lung cancer, focusing on the changes in the expression and function of various ion channels in lung cancer and how these changes affect lung cancer cell biology both in vitro and in vivo as evidenced by both genetic and pharmacological studies. It can help understand the molecular mechanisms of various ion channels influencing the initiation and progression of lung cancer and shed new insights into their roles in the development and treatment of this deadly disease.

Differential expression and inhibitory effects of aquaporins on the development of adenomyosis

Aquaporin 2 (AQP2), AQP5 and AQP8 participate in adenomyosis (AM). Ηowever, the roles of these three molecules in AM have not been fully elucidated. In the present study, Institute of Cancer Research female mice were used to establish a model of AM. Subsequently, the endometrial tissues of the mice were observed by hematoxylin-eosin staining, and AM severity, uterus diameter, uterus index, ovary index and numbers of nodules on the uterine surface were evaluated and counted. In addition, eutopic and ectopic endometrial stromal cells (ESCs) were isolated from eutopic and ectopic endometrial samples derived from patients with AM and were then identified by immunofluorescence. The viability, and migratory and invasive ability of ESCs transfected with small interfering RNA targeting AQP5 (siAQP5) were determined by Cell Counting Κit-8, scratch wound-healing and Transwell assays, respectively. Reverse transcription-quantitative polymerase chain reaction was performed to determine the mRNA expression levels of AQP5, epithelial-mesenchymal transition (EMT)-related genes (E-and N-cadherin), matrix metalloproteinase (MMP)-2 and −9. Protein expression levels of AQP2, AQP5, AQP8, E-, N-cadherin, MMP-2 and −9 were detected by western blotting. AM severity and uterus index were higher, and there were a greater number of nodules on the uterine surface in the AM group compared with the sham group. AQP2, AQP5 and AQP8 proteins were highly expressed in eutopic and ectopic endometrium of the AM group, and AQP5 was more highly expressed than AQP2 or AQP8. In addition, the data showed that Vimentin was positively expressed in ESCs, and that siAQP5 suppressed the mRNA expression levels of AQP5, cell viability, migration, invasion, EMT and MMP-2 and −9 expression in ESCs. In conclusion, AQP2, AQP5 and AQP8 were highly expressed in eutopic and ectopic endometrium. Notably, AQP5 silencing may suppress AM by inhibiting viability, migration, invasion, EMT, and MMP-2 and −9 expression in ESCs.

Aquaporin 5 promotes tumor migration and angiogenesis in non-small cell lung cancer cell line H1299

Non-small cell lung cancer (NSCLC) constitutes the majority of all lung-cancer cases. Aquaporin 5 (AQP5) may be involved in NSCLC by promoting lung-cancer initiation and progression. The present study aimed to determine the role of AQP5 in migration and angiogenesis using NSCLC cells and HUVECs. AQPs 1, 3, 4, 5, 8 and 9 were screened in the NSCLC cell line H1299, and the present results showed that AQP5 mRNA was upregulated compared with the other AQP genes. At the protein level, AQP5 was significantly increased in H1299 cells compared with 16HBE cells. AQP5 knockdown in H1299 cells significantly decreased cell migration compared with untransfected cells, as demonstrated by both Transwell and wound closure assays. The present study further investigated H1299 ability to promote HUVEC vascularisation. The supernatants of both transfected and untransfected H1299 cells were used as conditioned medium for HUVECs, and tube formation was measured. The supernatant of AQP5-downregulated cells exhibited significantly low tube formation potential compared with untransfected cells. Similarly, vascular endothelial growth factor was significantly increased in control cells (si-NC) compared with cells transfected with small interfering RNA targeting AQP5. The present study found that AQP5 downregulation significantly decreased the phosphorylation level of epidermal growth factor receptor and the activity of the ERK1/2 pathway. In summary, the present study suggested that AQP5 influenced migration and angiogenesis in NSCLCs in vitro and may potentially exhibit similar in vivo effects.

Pituitary Hormones (FSH, LH, PRL, and GH) Differentially Regulate AQP5 Expression in Porcine Ovarian Follicular Cells

This study aimed to examine the effect of follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), and growth hormone (GH) on Aquaporin 5 (AQP5) expression in granulosa (Gc) and theca cells (Tc) from medium (MF) and large (LF) ovarian follicles of pigs. The results showed that GH significantly decreased the expression of AQP5 in Gc from MF in relation to the control. In the Gc of large follicles, PRL stimulated the expression of AQP5. However, the increased expression of AQP5 in the Tc of LF was indicated by GH and PRL in relation to the control. A significantly higher expression of the AQP5 protein in the Gc from MF and LF was indicated by FSH and PRL. In co-cultures, an increased expression of AQP5 was observed in the Gc from LF incubated with LH, PRL, and GH. A significantly increased expression of AQP5 was also observed in co-cultures of Tc from all type of follicles incubated with LH, whereas PRL stimulated the expression of AQP5 in Tc from MF. Moreover, AQP5 protein expression increased in the co-culture isolated from MF and LF after treatment with FSH, LH, PRL, and GH. AQP5 immunoreactivity was observed in the cytoplasm, mainly in the perinuclear region and endosomes, as well as in the cell membranes of Gc and Tc from the LF and MF.