Effects of amiloride on physiological activity of stem cells of human lung cancer and possible mechanism

Interaction Between Allopregnanolone and Amiloride Binding Sites on the GABAA Receptor

Allopregnanolone (Allo) is a positive allosteric modulator of the GABAA receptor, and amiloride (Ami) is a competitive antagonist of the GABAA receptor. The purpose of this work was to study the combined effect of Allo and Ami on functional activity of GABAA receptor. The GABA-induced chloride current (IGABA) was measured in isolated Purkinje cells of rat cerebellum using the patch-clamp technique and a system of fast application. Our results indicate that Allo suppresses the inhibitory effect of Ami on IGABA, the IC50 value of Ami concentration-response curve was increased from 164 to 547 µM (P < 0.001) in the presence of Allo. Next, GABA concentration-response curves (EC50 = 5.8 µM) were constructed in the presence of Allo (EC50 = 1.2 µM), Ami (EC50 = 25.5 µM), and the combination of Allo+Ami (EC50 = 3.2 µM). Changes in EC50 values as a percentage relative to the control were calculated. The blocking effect of Ami is reduced in the presence of Allo (340% vs 150%, P < 0.01) and the potentiating effect of Allo does not change in the presence of Ami (78% vs 87%, P > 0.05). The results suggest that there is an allosteric relationship between the Allo and Ami binding sites on GABAA receptor that operates in one direction, from Allo sites to Ami site, but not vice versa.

Obesity-induced extracellular vesicles proteins drive the endometrial cancer pathogenesis: therapeutic potential of HO-3867 and Metformin

Endometrial cancer (EC) is the leading gynecologic malignancy in the United States with obesity implicated in 57% of cases. This research investigates the molecular complexities of extracellular vesicles (EV) secretion as carriers of oncogenic protein and their involvement in obesity-mediated EC. An understanding of these mechanisms is pivotal for unraveling pathways relevant to obesity-associated EC, thereby guiding the development of innovative prevention and treatment strategies. Our exploration revealed a significant increase in EV secretion carrying oncogenic proteins (TMEM205, STAT5, and FAS) in adipose and uterine tissues/serum samples from obese EC patients compared to control (without cancer). We identified alterations in EV-regulating proteins (Rab7, Rab11, and Rab27a) in obesity-mediated EC patients, adipose/uterine tissues, and serum samples. Through a 24-week analysis of the effects of a 45% kcal high-fat diet (HFD) on mice, we observed increased body weight, increased adipose tissue, enlarged uterine horns, and increased inflammation in the HFD group. This correlated with elevated levels of EV secretion and increased expression of oncogenic proteins TMEM205, FAS, and STAT5 and downregulation of the tumor suppressor gene PIAS3 in adipose and uterine tissues. Furthermore, our study confirmed that adipocyte derived EV increased EC cell proliferation, migration and xenograft tumor growth. Additionally, we identified that the small molecule inhibitors (HO-3867) or Metformin inhibited EV secretion in vitro and in vivo, demonstrating significant inhibition of high glucose or adipocyte-mediated EC cell proliferation and a reduction in body weight and adipose tissue accumulation when administered to HFD mice. Moreover, HO-3867 or Metformin treatment inhibited HFD induced hyperplasia (precursor of EC) by altering the expression of EV-regulated proteins and decreasing oncogenic protein expression levels. This study provides critical insights into the mechanisms underpinning obesity-mediated EV secretion with oncogenic protein expression, shedding light on their role in EC pathogenesis. Additionally, it offers pre-clinical evidence supporting the initiation of novel studies for EV-targeted therapies aimed at preventing obesity-mediated EC.

The role of microRNA-induced apoptosis in diverse radioresistant cancers

Resistance to cancer radiotherapy is one of the biggest concerns for success in treating and preventing recurrent disease. Malignant tumors may develop when they block genetic mutations associated with apoptosis or abnormal expression of apoptosis; Tumor treatment may induce the expression of apoptosis-related genes to promote tumor cell apoptosis. MicroRNAs have been shown to contribute to forecasting prognosis, distinguishing between cancer subtypes, and affecting treatment outcomes in cancer. Constraining these miRNAs may be an attractive treatment strategy to help overcome radiation resistance. The delivery of these future treatments is still challenging due to the excess downstream targets that each miRNA can control. Understanding the role of miRNAs brings us one step closer to attaining patient treatment and improving patient outcomes. This review summarized the current information on the role of microRNA-induced apoptosis in determining the radiosensitivity of various cancers.

Urokinase plasminogen activator as an anti-metastasis target: inhibitor design principles, recent amiloride derivatives, and issues with human/mouse species selectivity

The urokinase plasminogen activator (uPA) is a widely studied anticancer drug target with multiple classes of inhibitors reported to date. Many of these inhibitors contain amidine or guanidine groups, while others lacking these groups show improved oral bioavailability. Most of the X-ray co-crystal structures of small molecule uPA inhibitors show a key salt bridge with the side chain carboxylate of Asp189 in the S1 pocket of uPA. This review summarises the different classes of uPA inhibitors, their binding interactions and experimentally measured inhibitory potencies and highlights species selectivity issues with attention to recently described 6-substituted amiloride and 5‑N,N-(hexamethylene)amiloride (HMA) derivatives.

Verticillium wilt resistant and susceptible olive cultivars express a very different basal set of genes in roots

BACKGROUND

Olive orchards are threatened by a wide range of pathogens. Of these, Verticillium dahliae has been in the spotlight for its high incidence, the difficulty to control it and the few cultivars that has increased tolerance to the pathogen. Disease resistance not only depends on detection of pathogen invasion and induction of responses by the plant, but also on barriers to avoid the invasion and active resistance mechanisms constitutively expressed in the absence of the pathogen. In a previous work we found that two healthy non-infected plants from cultivars that differ in V. dahliae resistance such as 'Frantoio' (resistant) and 'Picual' (susceptible) had a different root morphology and gene expression pattern. In this work, we have addressed the issue of basal differences in the roots between Resistant and Susceptible cultivars.

RESULTS

The gene expression pattern of roots from 29 olive cultivars with different degree of resistance/susceptibility to V. dahliae was analyzed by RNA-Seq. However, only the Highly Resistant and Extremely Susceptible cultivars showed significant differences in gene expression among various groups of cultivars. A set of 421 genes showing an inverse differential expression level between the Highly Resistant to Extremely Susceptible cultivars was found and analyzed. The main differences involved higher expression of a series of transcription factors and genes involved in processes of molecules importation to nucleus, plant defense genes and lower expression of root growth and development genes in Highly Resistant cultivars, while a reverse pattern in Moderately Susceptible and more pronounced in Extremely Susceptible cultivars were observed.

CONCLUSION

According to the different gene expression patterns, it seems that the roots of the Extremely Susceptible cultivars focus more on growth and development, while some other functions, such as defense against pathogens, have a higher expression level in roots of Highly Resistant cultivars. Therefore, it seems that there are constitutive differences in the roots between Resistant and Susceptible cultivars, and that susceptible roots seem to provide a more suitable environment for the pathogen than the resistant ones.

Screening of 5- and 6-Substituted Amiloride Libraries Identifies Dual-uPA/NHE1 Active and Single Target-Selective Inhibitors

The K⁺-sparing diuretic amiloride shows off-target anti-cancer effects in multiple rodent models. These effects arise from the inhibition of two distinct cancer targets: the trypsin-like serine protease urokinase-type plasminogen activator (uPA), a cell-surface mediator of matrix degradation and tumor cell invasiveness, and the sodium-hydrogen exchanger isoform-1 (NHE1), a central regulator of transmembrane pH that supports carcinogenic progression. In this study, we co-screened our library of 5- and 6-substituted amilorides against these two targets, aiming to identify single-target selective and dual-targeting inhibitors for use as complementary pharmacological probes. Closely related analogs substituted at the 6-position with pyrimidines were identified as dual-targeting (pyrimidine 24 uPA IC₅₀ = 175 nM, NHE1 IC₅₀ = 266 nM, uPA selectivity ratio = 1.5) and uPA-selective (methoxypyrimidine 26 uPA IC₅₀ = 86 nM, NHE1 IC₅₀ = 12,290 nM, uPA selectivity ratio = 143) inhibitors, while high NHE1 potency and selectivity was seen with 5-morpholino (29 NHE1 IC₅₀ = 129 nM, uPA IC₅₀ = 10,949 nM; NHE1 selectivity ratio = 85) and 5-(1,4-oxazepine) (30 NHE1 IC₅₀ = 85 nM, uPA IC₅₀ = 5715 nM; NHE1 selectivity ratio = 67) analogs. Together, these amilorides comprise a new toolkit of chemotype-matched, non-cytotoxic probes for dissecting the pharmacological effects of selective uPA and NHE1 inhibition versus dual-uPA/NHE1 inhibition.

Antihypertensive Drugs and Risk of Cancer: Between Scylla and Charybdis

Antihypertensive drugs namely angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, beta blockers, and diuretics are among the most clearly documented regimens worldwide with an overall cardioprotective benefit. Given that malignancy is the second leading cause of mortality, numerous observational studies aimed to investigate the carcinogenic potential of these agents with conflicting results. The purpose of this review was to summarize current data in an effort to explore rare side effects and new mechanisms linking antihypertensive drugs with the risk of developing cancer.