Auphen and dibutyryl cAMP suppress growth of hepatocellular carcinoma by regulating expression of aquaporins 3 and 9 in vivo

The Expanding Role of Aquaporin-1, Aquaporin-3 and Aquaporin-5 as Transceptors: Involvement in Cancer Development and Potential Druggability

Aquaporins (AQPs) are transmembrane proteins that facilitate the transport of water and small solutes, including glycerol, hydrogen peroxide and ions, across cell membranes. Beyond their established physiological roles in water regulation and metabolic processes, AQPs also exhibit receptor-like signaling activities in cancer-associated signaling pathways, integrating the dual roles of transporters and receptors, hence functioning as transceptors. This dual functionality underpins their critical involvement in cancer biology, where AQPs play key roles in promoting cell proliferation, migration, and invasion, contributing significantly to carcinogenesis. Among the AQPs, AQP1, AQP3 and AQP5 have been consistently identified as being aberrantly expressed in various tumor types. Their overexpression is strongly associated with tumor progression, metastasis, and poor patient prognosis. This review explores the pivotal roles of AQP1, AQP3 and AQP5 as transceptors in cancer biology, underscoring their importance as pharmacological targets. It highlights the urgent need for the development of effective modulators to target these AQPs, offering a promising avenue to enhance current therapeutic approaches for cancer treatment.

Evaluation of the Mammalian Aquaporin Inhibitors Auphen and Z433927330 in Treating Breast Cancer

AQPs contribute to breast cancer progression and metastasis. We previously found that genetic inhibition of Aqp7 reduces primary tumor burden and metastasis in breast cancer. In this study, we utilized two AQP inhibitors, Auphen and Z433927330, to evaluate the efficacy of therapeutic inhibition of AQPs in breast cancer treatment. The inhibitors were evaluated in breast cancer for both cytotoxicity and metabolic stability assays across both murine and human breast cancer cell lines. Both AQP inhibitors also affected the expression of other AQP transcripts and proteins, which demonstrates compensatory regulation between AQP family members. As a single agent, Auphen treatment in vivo extended overall survival but did not impact primary or metastatic tumor burden. However, Auphen treatment made cells more responsive to chemotherapy (doxorubicin) or endocrine treatment (tamoxifen, fulvestrant). In fact, treatment with Tamoxifen reduced overall AQP7 protein expression. RNA-seq of breast cancer cells treated with Auphen identified mitochondrial metabolism genes as impacted by Auphen and may contribute to reducing mammary tumor progression, lung metastasis, and increased therapeutic efficacy of endocrine therapy in breast cancer. Interestingly, we found that Auphen and tamoxifen cooperate to reduce breast cancer cell viability, which suggests that Auphen treatment makes the cells more susceptible to Tamoxifen. Together, this study highlights AQPs as therapeutic vulnerabilities of breast cancer metastasis that are promising and should be exploited. However, the pharmacologic results suggest additional chemical refinements and optimization of AQP inhibition are needed to make these AQP inhibitors appropriate to use for therapeutic benefit in overcoming endocrine therapy resistance.

Aquaporins: New players in breast cancer progression and treatment response

Aquaporins (AQPs) are a family of small transmembrane proteins that selectively transport water and other small molecules and ions following an osmotic gradient across cell plasma membranes. This enables them to regulate numerous functions including water homeostasis, fat metabolism, proliferation, migration, and adhesion. Previous structural and functional studies highlight a strong biological relationship between AQP protein expression, localization, and key biological functions in normal and cancer tissues, where aberrant AQP expression correlates with tumorigenesis and metastasis. In this review, we discuss the roles of AQP1, AQP3, AQP4, AQP5, and AQP7 in breast cancer progression and metastasis, including the role of AQPs in the tumor microenvironment, to highlight potential contributions of stromal-derived to epithelial-derived AQPs to breast cancer. Emerging evidence identifies AQPs as predictors of response to cancer therapy and as targets for increasing their sensitivity to treatment. However, these studies have not evaluated the requirements for protein structure on AQP function within the context of breast cancer. We also examine how AQPs contribute to a patient's response to cancer treatment, existing AQP inhibitors and how AQPs could serve as novel predictive biomarkers of therapy response in breast cancer. Future studies also should evaluate AQP redundancy and compensation as mechanisms used to overcome aberrant AQP function. This review highlights the need for additional research into how AQPs contribute molecularly to therapeutic resistance and by altering the tumor microenvironment.

Clinical value and molecular mechanism of AQGPs in different tumors

Aquaglyceroporins (AQGPs), including AQP3, AQP7, AQP9, and AQP10, are transmembrane channels that allow small solutes across biological membranes, such as water, glycerol, H₂O₂, and so on. Increasing evidence suggests that they play critical roles in cancer. Overexpression or knockdown of AQGPs can promote or inhibit cancer cell proliferation, migration, invasion, apoptosis, epithelial-mesenchymal transition and metastasis, and the expression levels of AQGPs are closely linked to the prognosis of cancer patients. Here, we provide a comprehensive and detailed review to discuss the expression patterns of AQGPs in different cancers as well as the relationship between the expression patterns and prognosis. Then, we elaborate the relevance between AQGPs and malignant behaviors in cancer as well as the latent upstream regulators and downstream targets or signaling pathways of AQGPs. Finally, we summarize the potential clinical value in cancer treatment. This review will provide us with new ideas and thoughts for subsequent cancer therapy specifically targeting AQGPs.

Aquaglyceroporin Modulators as Emergent Pharmacological Molecules for Human Diseases

Aquaglyceroporins, a sub-class of aquaporins that facilitate the diffusion of water, glycerol and other small uncharged solutes across cell membranes, have been recognized for their important role in human physiology and their involvement in multiple disorders, mostly related to disturbed energy homeostasis. Aquaglyceroporins dysfunction in a variety of pathological conditions highlighted their targeting as novel therapeutic strategies, boosting the search for potent and selective modulators with pharmacological properties. The identification of selective inhibitors with potential clinical applications has been challenging, relying on accurate assays to measure membrane glycerol permeability and validate effective functional blockers. Additionally, biologicals such as hormones and natural compounds have been revealed as alternative strategies to modulate aquaglyceroporins via their gene and protein expression. This review summarizes the current knowledge of aquaglyceroporins’ involvement in several pathologies and the experimental approaches used to evaluate glycerol permeability and aquaglyceroporin modulation. In addition, we provide an update on aquaglyceroporins modulators reported to impact disease, unveiling aquaglyceroporin pharmacological targeting as a promising approach for innovative therapeutics.

Prognostic Role of mRNA-Expression of Aquaporins (AQP) 3, 4, 7 and 9 in Stage pT1 Non-Muscle-Invasive Bladder Cancer

BACKGROUND

AQP proteins show a variety of functions in human cell metabolism. The role of different AQP subtypes in tumor metabolism and prognosis are subject of ongoing research.

OBJECTIVE

To investigate the mRNA expression of Aquaporin (AQP) 3, 4, 7 and 9 in pT1 non-muscle-invasive bladder cancer (NMIBC) and its prognostic value in therapeutic decision making.

METHODS

Formalin-fixed-paraffin-embedded (FFPE) tissues from transurethral resection of the bladder (TURB) from 112 patients with initial diagnosis of stage pT1 NMIBC were analyzed retrospectively together with clinical data and therapeutic approaches. mRNA expression of AQP3, 4, 7 and 9 was measured and quantified using RT-qPCR.

RESULTS

Of the 112 patients (83.9%male, median age 72 years), 40 had a recurrence (35.7%), 16 a progression (14.3%) and 14 patients (12.5%) died tumor-related. mRNA expression for AQP3 was detected in 99.1%, AQP4 in 46.4%, AQP7 in 86.6%and AQP9 in 97.3%. Spearman analysis revealed statistically significant correlations between AQP3, AQP7 and AQP9 mRNA expression with adverse clinical and histopathological parameters (WHO1973 grade 3, concomitant Cis or multifocality). High AQP9 mRNA expression was associated with worse PFS in the total cohort (p = 0.034) and in Grade 3 tumors (p = 0.003) in Kaplan-Meier analysis. In patients with bladder sparing approach, high AQP3 mRNA expression was significantly associated with worse CSS in patients receiving BCG therapy (p = 0.029).

CONCLUSIONS

mRNA expression of AQP3, 7 and 9 correlates with adverse clinical and pathological parameters. AQP3 and 9 may help to identify a subgroup of highest risk patients who may be considered for early cystectomy.

Long Non-coding RNA LINC00320 Inhibits Tumorigenicity of Glioma Cells and Angiogenesis Through Downregulation of NFKB1-Mediated AQP9

The inhibitory effect of long intergenic non-coding RNA 00320 (LINC00320) in glioma cell proliferation has been proposed in a recent study. However, the mechanisms by which LINC00320 regulate aquaporin 9 (AQP9) in glioma require further exploration. Hence, this study aims to investigate effects of LINC00320 on tumorigenicity of glioma cells and angiogenesis of microvascular endothelial cells (MVECs). Expression of LINC00320 and AQP9 in glioma tissues and cells was measured by reverse transcription–quantitative polymerase chain reaction and Western blot analysis. The relationship among LINC00320, nuclear factor κB subunit 1 (NFKB1) and AQP9 was examined by RNA immunoprecipitation, dual-luciferase reporter gene, and chromatin immunoprecipitation assays. The participation of LINC00320 and AQP9 in glioma cell proliferation and MVEC angiogenesis was analyzed using gain- and loss-of-function approaches. Finally, a nude mouse orthotopic xenograft model of glioma was established to investigate the effects of LINC00320 and AQP9 on glioma growth in vivo. LINC00320 was under-expressed and AQP9 was over-expressed in glioma tissues. Further mechanistic investigation showed that LINC00320 downregulated AQP9 by inhibiting the recruitment of NFKB1 to the promoter region of AQP9. LINC00320 overexpression or AQP9 silencing inhibited the proliferation of glioma cells and angiogenesis of MVECs. Also, upregulation of LINC00320 restrained tumor growth and angiogenesis in xenograft mice by downregulating AQP9. Taken together, LINC00320 acts as a tumor suppressor in glioma, thus presenting a novel therapeutic target.

Assessing the Expression of Aquaporin 3 Antigen-Recognition Sites in Oral Squamous Cell Carcinoma

Aquaporin 3 (AQP3) serves as a water and glycerol transporter facilitating epithelial cell hydration. Recently, the involvement of AQP3 in cancers has been reported. However, the immunohistochemical expression of AQP3 in carcinomas remains controversial. We hypothesized that differences in aquaporin 3 antigen recognition (AQP3 AR) may influence their expressions. Thus, our study aimed to assess the immunostaining patterns of 3 AQP3 AR sites in oral squamous cell carcinoma (OSCC) and to compare the adjacent areas of high-grade epithelial dysplasia (HG-ED) and normal oral mucosa (NOM). The study group included formalin-fixed OSCC samples (n=51) with adjacent regions of HG-ED (n=12) and NOM (n=51). The tissues were stained with anti-AQP3 antibodies (AR sites at amino acid (AA) 250-C terminus, AA180-228, and N terminus AA1-80) by immunohistochemistry. Our results showed that strong membranous immunostaining was observed for AQP3 AR sites at the AA250-C terminus and AA180-228 in all the samples for NOM and weak AQP3 immunostaining for both the AR sites in all the 12 samples for HG-ED. The invasive front of OSCC samples showed that AQP3 AR at the AA250-C terminus decreased in 42/51 samples (82.4%) and AA180-228 in 47/51 samples (92.2%). Conversely, in the AQP3 AR site at N terminus AA1-80, all samples of the NOM showed negative or slightly positive staining in the cytoplasm of the lower layers. AQP3 expression was increased in 12/12 cases (100%) and 46/51 cases (90.2%) in the HG-ED and invasive front of OSCC, respectively. AQP3 may be used as a biomarker for detecting malignant transformations. AQP3 AR site differences influence their immunohistochemical expression in OSCC.

Important players in carcinogenesis as potential targets in cancer therapy: an update

The development of cancer is a problem that has accompanied mankind for years. The growing number of cases, emerging drug resistance, and the need to reduce the serious side effects of pharmacotherapy are forcing scientists to better understand the complex mechanisms responsible for the initiation, promotion, and progression of the disease. This paper discusses the modulation of the particular stages of carcinogenesis by selected physiological factors, including: acetylcholine (ACh), peroxisome proliferator-activated receptors (PPAR), fatty acid-binding proteins (FABPs), Bruton's tyrosine kinase (Btk), aquaporins (AQPs), insulin-like growth factor-2 (IGF-2), and exosomes. Understanding their role may contribute to the development of more effective and safer therapies based on new binding sites.

Combined Systematic Review and Transcriptomic Analyses of Mammalian Aquaporin Classes 1 to 10 as Biomarkers and Prognostic Indicators in Diverse Cancers

Aquaporin (AQP) channels enable regulated transport of water and solutes essential for fluid homeostasis, but they are gaining attention as targets for anticancer therapies. Patterns of AQP expression and survival rates for patients were evaluated by systematic review (PubMed and Embase) and transcriptomic analyses of RNAseq data (Human Protein Atlas database). Meta-analyses confirmed predominantly negative associations between AQP protein and RNA expression levels and patient survival times, most notably for AQP1 in lung, breast and prostate cancers; AQP3 in esophageal, liver and breast cancers; and AQP9 in liver cancer. Patterns of AQP expression were clustered for groups of cancers and associated with risk of death. A quantitative transcriptomic analysis of AQP1-10 in human cancer biopsies similarly showed that increased transcript levels of AQPs 1, 3, 5 and 9 were most frequently associated with poor survival. Unexpectedly, increased AQP7 and AQP8 levels were associated with better survival times in glioma, ovarian and endometrial cancers, and increased AQP11 with better survival in colorectal and breast cancers. Although molecular mechanisms of aquaporins in pathology or protection remain to be fully defined, results here support the hypothesis that overexpression of selected classes of AQPs differentially augments cancer progression. Beyond fluid homeostasis, potential roles for AQPs in cancers (suggested from an expanding appreciation of their functions in normal tissues) include cell motility, membrane process extension, transport of signaling molecules, control of proliferation and apoptosis, increased mechanical compliance, and gas exchange. AQP expression also has been linked to differences in sensitivity to chemotherapy treatments, suggesting possible roles as biomarkers for personalized treatments. Development of AQP pharmacological modulators, administered in cancer-specific combinations, might inspire new interventions for controlling malignant carcinomas.

Gender Differences in Adipocyte Metabolism and Liver Cancer Progression

Liver cancer is the third most common cancer type and the second leading cause of deaths in men. Large population studies have demonstrated remarkable gender disparities in the incidence and the cumulative risk of liver cancer. A number of emerging risk factors regarding metabolic alterations associated with obesity, diabetes and dyslipidemia have been ascribed to the progression of non-alcoholic fatty liver diseases (NAFLD) and ultimately liver cancer. The deregulation of fat metabolism derived from excessive insulin, glucose, and lipid promotes cancer-causing inflammatory signaling and oxidative stress, which eventually triggers the uncontrolled hepatocellular proliferation. This review presents the current standing on the gender differences in body fat compositions and their mechanistic linkage with the development of NAFLD-related liver cancer, with an emphasis on genetic, epigenetic and microRNA control. The potential roles of sex hormones in instructing adipocyte metabolic programs may help unravel the mechanisms underlying gender dimorphism in liver cancer and identify the metabolic targets for disease management.