Drug repurposing for anticancer therapies. A lesson from proton pump inhibitors

How Does Cancer Occur? How Should It Be Treated? Treatment from the Perspective of Alkalization Therapy Based on Science-Based Medicine

This review article investigates the relationship between mitochondrial dysfunction and cancer progression, emphasizing the metabolic shifts that promote tumor growth. Mitochondria are crucial for cellular energy production, but they also play a significant role in cancer progression by promoting glycolysis even under oxygen-rich conditions, a phenomenon known as the Warburg effect. This metabolic reprogramming enables cancer cells to maintain an alkaline internal pH and an acidic external environment, which are critical for their proliferation and survival in hypoxic conditions. The article also explores the acidic tumor microenvironment (TME), a consequence of intensive glycolytic activity and proton production by cancer cells. This acidic milieu enhances the invasiveness and metastatic potential of cancer cells and contributes to increased resistance to chemotherapy. Alkalization therapy, which involves neutralizing this acidity through dietary modifications and the administration of alkalizing agents such as sodium bicarbonate, is highlighted as an effective strategy to counteract these adverse conditions and impede cancer progression. Integrating insights from science-based medicine, the review evaluates the effectiveness of alkalization therapy across various cancer types through clinical assessments. Science-based medicine, which utilizes inductive reasoning from observed clinical outcomes, lends support to the hypothesis of metabolic reprogramming in cancer treatment. By addressing both metabolic and environmental disruptions, this review suggests that considering cancer as primarily a metabolic disorder could lead to more targeted and effective treatment strategies, potentially improving outcomes for patients with advanced-stage cancers.

Tackling multi-drug resistant fungi by efflux pump inhibitors

The emergence of multidrug-resistant fungi is of grave concern, and its infections are responsible for significant deaths among immunocompromised patients. The treatment of fungal infections primarily relies on a clinical class of antibiotics, including azoles, polyenes, echinocandins, polyketides, and a nucleotide analogue. However, the incidence of fungal infections is increasing as the treatment for human and plant fungal infections overlaps with antifungal drugs. The need for new antifungal agents acting on different targets than known targets is undeniable. Also, the pace at which loss of fungal susceptibility to antibiotics cannot be undermined. There are several modes by which fungi can develop resistance to antibiotics, including reduced drug uptake, drug target alteration, and a reduction in the cellular concentration of the drug due to active extrusions and biofilm formation. The efflux pump's overexpression in the fungi primarily reduced the antibiotic's concentration to a sub-lethal concentration, thus responsible for developing resistant fungus strains. Several strategies are used to check antibiotic resistance in multi-drug resistant fungi, including synthesizing antibiotic analogs and giving antibiotics in combination therapies. Among them, the efflux pump protein inhibitors are considered potential adjuvants to antibiotics and can block the efflux of antibiotics by inhibiting efflux pump protein transporters. Moreover, it can sensitize the antifungal drugs to multi-drug resistant fungi with overexpressed efflux pump proteins. This review discusses the natural lead molecules, repurposable drugs, and formulation strategies to overcome the efflux pump activity in the fungi.

Improving the treatment of bacterial infections caused by multidrug-resistant bacteria through drug repositioning

Drug repurposing (repositioning) is a dynamically-developing area in the search for effective therapy of infectious diseases. Repositioning existing drugs with a well-known pharmacological and toxicological profile is an attractive method for quickly discovering new therapeutic indications. The off-label use of drugs for infectious diseases requires much less capital and time, and can hasten progress in the development of new antimicrobial drugs, including antibiotics. The use of drug repositioning in searching for new therapeutic options has brought promising results for many viral infectious diseases, such as Ebola, ZIKA, Dengue, and HCV. This review describes the most favorable results for repositioned drugs for the treatment of bacterial infections. It comprises publications from various databases including PubMed and Web of Science published from 2015 to 2023. The following search keywords/strings were used: drug repositioning and/or repurposing and/or antibacterial activity and/or infectious diseases. Treatment options for infections caused by multidrug-resistant bacteria were taken into account, including methicillin-resistant staphylococci, multidrug-resistant Mycobacterium tuberculosis, or carbapenem-resistant bacteria from the Enterobacteriaceae family. It analyses the safety profiles of the included drugs and their synergistic combinations with antibiotics and discusses the potential of antibacterial drugs with antiparasitic, anticancer, antipsychotic effects, and those used in metabolic diseases. Drug repositioning may be an effective response to public health threats related to the spread of multidrug-resistant bacterial strains and the growing antibiotic resistance of microorganisms.

A review of lactate-lactylation in malignancy: its potential in immunotherapy

Lactic acid was formerly regarded as a byproduct of metabolism. However, extensive investigations into the intricacies of cancer development have revealed its significant contributions to tumor growth, migration, and invasion. Post-translational modifications involving lactate have been widely observed in histone and non-histone proteins, and these modifications play a crucial role in regulating gene expression by covalently attaching lactoyl groups to lysine residues in proteins. This discovery has greatly enhanced our comprehension of lactic acid's involvement in disease pathogenesis. In this article, we provide a comprehensive review of the intricate relationship between lactate and tumor immunity, the occurrence of lactylation in malignant tumors, and the exploitation of targeted lactate-lactylation in tumor immunotherapy. Additionally, we discuss future research directions, aiming to offer novel insights that could inform the investigation, diagnosis, and treatment of related diseases.

Repurposing of rabeprazole as an anti-Trypanosoma cruzi drug that targets cellular triosephosphate isomerase

Trypanosoma cruzi is the causative agent of American trypanosomiasis, which mainly affects populations in Latin America. Benznidazole is used to control the disease, with severe effects in patients receiving this chemotherapy. Previous studies have demonstrated the inhibition of triosephosphate isomerase from T. cruzi, but cellular enzyme inhibition has yet to be established. This study demonstrates that rabeprazole inhibits both cell viability and triosephosphate isomerase activity in T. cruzi epimastigotes. Our results show that rabeprazole has an IC50 of 0.4 µM, which is 14.5 times more effective than benznidazole. Additionally, we observed increased levels of methyl-glyoxal and advanced glycation end products after the inhibition of cellular triosephosphate isomerase by rabeprazole. Finally, we demonstrate that the inactivation mechanisms of rabeprazole on triosephosphate isomerase of T. cruzi can be achieved through the derivatization of three of its four cysteine residues. These results indicate that rabeprazole is a promising candidate against American trypanosomiasis.

Esomeprazole Alleviates Cisplatin Resistance by Inhibiting the AKT/mTOR Pathway in Ovarian Cancer Cells

Purpose

Ovarian cancer is the most lethal malignancy in gynecology. Due to limited treatment strategies and platinum resistance, newer drugs and therapeutic options are needed. Esomeprazole (ESO) has been reported to have multiple anticancer activities in preclinical and clinical research. Therefore, this study aimed to explore the anticancer effects of esomeprazole on ovarian cancer and its underlying molecular mechanisms.

Methods

CCK-8 and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to detect cell viability and proliferation. The Transwell assay was used to evaluate cell migration and invasion capacity. Flow cytometry was used to detect cell apoptosis. Western blotting and immunofluorescence were used to detect protein expression.

Results

ESO effectively inhibited the cell viability, proliferation, invasion, migration, and induced apoptosis of ovarian cancer cells in a concentration-dependent manner. Treatment with ESO decreased the expression of c-MYC, SKP2, E2F1, N-cadherin, vimentin, and matrix metalloproteinase 2 (MMP2), while it increased E-cadherin, caspase3, p53, BAX, and cleaved poly (ADP-ribose) polymerase (PARP) expression, and downregulated the PI3K/AKT/mTOR signaling pathway. Furthermore, ESO combined with cisplatin showed synergistic effects in inhibiting proliferation, invasion, and migration of cisplatin-resistant ovarian cancer cells. The mechanism may be related to the increased inhibition of c-MYC, epithelial-mesenchymal transition (EMT), and the AKT/mTOR signaling pathway and enhanced the upregulation of the pro-apoptotic protein BAX and cleaved PARP levels. Moreover, ESO combined with cisplatin synergistically upregulated the expression of the DNA damage marker γH2A.X.

Conclusion

ESO exerts multiple anticancer activities and has a synergistic effect in combination with cisplatin on cisplatin-resistant ovarian cancer cells. This study provides a promising strategy to improve chemosensitivity and overcome resistance to cisplatin in ovarian cancer.

Effect of Antacid Use on Immune Checkpoint Inhibitors in Advanced Solid Cancer Patients: A Systematic Review and Meta-analysis

The influence of antacids use on immune checkpoint inhibitor (ICI) efficacy remains unclear. A systematic review and meta-analysis was performed to evaluate the effect of proton pump inhibitors (PPIs) and histamine-2-receptor antagonists (H2RAs) on ICI efficacy in advanced solid cancer patients. A systematic literature search in PubMed, EMBASE, and Web of Science was performed to retrieve studies investigating the effect of antacid use on ICI efficacy. Overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and immune-related adverse events were measured using hazard ratios (HRs) or odds ratios (ORs). Thirty studies enrolling 16,147 advanced cancer patients receiving ICI treatment were included. The pooled analysis indicated that PPI use was associated with shorter OS (HR=1.40, 95% CI, 1.25-1.57) and PFS (HR=1.34, 95% CI, 1.19-1.52) in advanced cancer patients treated with ICIs. PPI use did not show effect on ORR or immune-related adverse event of advanced cancer patients receiving ICI treatment. OS, PFS, and ORR did not differ between H2RA users and non-H2RA users. In subgroup analyses, PPI use was associated with shorter OS and PFS in NSCLC and urothelial carcinoma patients and in patients treated with anti-programmed cell death 1 or anti-programmed cell death ligand 1 monotherapy. In addition, ICI efficacy was different in the antacid exposure time frame subgroups. In conclusion, PPI use has a negative effect on OS and PFS among advanced cancer patients receiving ICI treatment. PPIs should be cautiously administered among advanced cancer patients treated with ICI. The safety of H2RAs and the influence of H2RAs on ICI efficacy need further investigation.

Inhibitory effect of roburic acid in combination with docetaxel on human prostate cancer cells

Roburic acid (ROB) is a naturally occurred tetracyclic triterpenoid, and the anticancer activity of this compound has not been reported. Docetaxel (DOC) is the first-line chemotherapeutic agent for advanced stage prostate cancer but toxic side effects and drug resistance limit its clinical success. In this study, the potential synergistic anticancer effect and the underlying mechanisms of ROB in combination with DOC on prostate cancer were investigated. The results showed that ROB and DOC in combination synergistically inhibited the growth of prostate cancer cells. The combination also strongly induced apoptosis, and suppressed cell migration, invasion and sphere formation. Mechanistic study showed that the combined effects of ROB and DOC on prostate cancer cells were associated with inhibition of NF-κB activation, down regulation of Bcl-2 and up regulation of Bax. Knockdown of NF-κB by small interfering RNA (siRNA) significantly decreased the combined effect of ROB and DOC. Moreover, we found that esomeprazole (ESOM), a proton pump inhibitor (PPI), strongly enhanced the effectiveness of ROB and DOC on prostate cancer cells in acidic culture medium. Since acidic micro environment is known to impair the efficacy of current anticancer therapies, ESOM combined with ROB and DOC may be an effective approach for improving the treatment of prostate cancer patients.

Back to basic: Trials and tribulations of alkalizing agents in cancer

"Dysregulated" metabolism is a characteristic of the cancer cell phenotype. This includes persistent use of glycolytic metabolism in normoxic environments (Warburg effect) leading to increased acid production and accumulation of protons in the interstitial space. Although often thought to be disordered, altered cancer metabolism is the outcome of intense Darwinian selection and, thus, must have evolved to maximize cancer cell fitness. In an evolutionary context, cancer-induced acidification of the microenvironment represents a niche construction strategy to promote proliferation. Ecological advantages conferred on the cancer population included remodeling of the extracellular matrix to promote local invasion, suppression of potential competitive proliferation of fibroblasts, and suppression of host immune response. Preclinical data demonstrates that increasing the serum buffering capacity (through, for example, oral sodium bicarbonate and TRIS) can neutralize the acidic tumor microenvironment with inhibition local invasion and proliferation which can be synergistic with the effects of chemotherapy and immunotherapy agents. Here, we describe the proton dynamics in cancer and their influence on tumor progression and metastasis. Additionally, we will discuss targeting the tumor acidosis with alkalizing agents including our bicarbonate clinical trial results.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT01350583, NCT01198821 and NCT01846429.

Proposal to Consider Chemical/Physical Microenvironment as a New Therapeutic Off-Target Approach

The molecular revolution could lead drug discovery from chance observation to the rational design of new classes of drugs that could simultaneously be more effective and less toxic. Unfortunately, we are witnessing some failure in this sense, and the causes of the crisis involve a wide range of epistemological and scientific aspects. In pharmacology, one key point is the crisis of the paradigm the “magic bullet”, which is to design therapies based on specific molecular targets. Drug repurposing is one of the proposed ways out of the crisis and is based on the off-target effects of known drugs. Here, we propose the microenvironment as the ideal place to direct the off-targeting of known drugs. While it has been extensively investigated in tumors, the generation of a harsh microenvironment is also a phenotype of the vast majority of chronic diseases. The hostile microenvironment, on the one hand, reduces the efficacy of both chemical and biological drugs; on the other hand, it dictates a sort of “Darwinian” selection of those cells armed to survive in such hostile conditions. This opens the way to the consideration of the microenvironment as a convenient target for pharmacological action, with a clear example in proton pump inhibitors.

Association between use of antacid medications (proton pump inhibitors and histamine-2 receptor antagonists) and the incidence of lung cancer: A population-based cohort analysis

This study investigated the association between antacid administration and lung cancer incidence in a real-world setting. This was a nationwide, retrospective cohort study. The cohort comprised random samples (n = 1,031,392) from the entire South Korean population in 2002. The duration of antacid administration between January 2006 and December 2010 was recorded for each participant. Newly developed lung cancers were counted during the 5-year observation period (January 1, 2006 to December 31, 2010). A total of 437,370 participants aged ≥ 40 years were included, of whom 301,201 (68.9%) had antacid exposure before the diagnosis of lung cancer. A total of 1230 (0.28%) antacid-exposed patients developed lung cancer. Among patients with no antacid exposure or underexposure (n = 136,171), 597 (0.44%) developed lung cancer. In the multivariable analysis, antacid exposure before the diagnosis of lung cancer was independently associated with a reduced incidence of lung cancer (hazard ratio: 0.64; 95% confidence interval: 0.55-0.74; P < .001). Antacid use might be independently associated with a decreased risk of lung cancer development in this cohort study.

Meaning and Significance of “Alkalization Therapy for Cancer”

Objectives of the Study

Our research aims to answer the following questions. Can cancer progression be stopped by changing the body condition of person with cancer? Can cancer be cured?If cancer progression can be stopped, what is the underlying mechanism?

Theoretical Rationale for Alkalization Therapy

Almost 70 years ago, Goldblatt H. & Cameron G. reported on the idea of alkalization therapy. Before that, Otto Warburg had been studying the metabolism of cancer and had discovered the essential nature of cancer. He published a review in Science in 1956 under the title “On the origin of cancer cells”. From his phenomena described above, we established the theoretical rationale for alkalization therapy, based on the question of “How does cancer form and what is its nature”?

Limitations of Deductive Methods and Inductive Approaches

In this paper, we describe a method to reconstruct the limitations and weaknesses of modern cancer medicine as Science-based Medicine using an inductive method, and to present a new vision of cancer therapy. How should we treat cancer? (Case presentation): Using a specific clinical case, we present patients in whom were successfully treated with no or few anticancer drugs.

Summary

The biggest weakness of current cancer treatments is that they only treat the cancer and not the actual patient. The “alkalization therapy” that we advocate does not compete with any of the current standard treatments, but improves the effectiveness of standard treatments, reduces side effects, and lowers medical costs.

A review on lactoferrin as a proton pump inhibitor

Lactoferrin (Lf) is a versatile natural milk-derived protein that exhibits multiple interesting biological activities. Since it is safe for human administration and currently manufactured using low cost and well-established large-scale processes, the Lf scientific community has been devoted at dissecting its mechanisms of action towards its more rational and efficient use for various applications. Emerging literature has identified proton pumping ATPases as molecular targets of Lf in different cellular models linked to distinct activities of this natural protein. Information on this subject has not been systematically analysed before, hence herein we review the current state of art on the effect of Lf on proton pumping ATPases. Though structurally different, we propose that Lf holds a proton pump inhibitor (PPI)-like activity based on the functional resemblance with the classical inhibitors of the stomach H⁺/K⁺-ATPase. The downstream events and outcomes of the PPI-like activity of Lf, as well as its impact for the development of improved Lf applications are also discussed.

An Up-To-Date Investigation Into the Correlation Between Proton Pump Inhibitor Use and the Clinical Efficacy of Immune Checkpoint Inhibitors in Advanced Solid Cancers: A Systematic Review and Meta-Analysis

Background

Although immune checkpoint inhibitors (ICIs) have revolutionized the current anticancer therapies, a considerable proportion of patients are found to hardly benefit from these drugs. Accumulating studies have demonstrated that concomitant proton pump inhibitor (PPI) use may affect the clinical efficacy of ICIs; however, their results are inconsistent. In this study, based on updated evidence, we aimed to perform a meta-analysis to clarify the prognostic significance of PPI use in advanced solid cancer patients receiving ICI therapy.

Methods

Eligible literature was searched using PubMed, Cochrane Library, Web of Science, EMBASE, and other network resources before July 2021. Clinical outcome was evaluated using overall survival (OS) and progression-free survival (PFS). The correlation of PPI use with OS or PFS was determined based on hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

A total of 17 studies enrolling 9,978 ICI-treated cancer patients were included in our meta-analysis. The global analysis demonstrated that PPI use was significantly correlated with worse OS [HR = 1.29 (1.10-1.50)] instead of PFS [HR = 1.19 (0.98-1.44)] in solid cancer patients receiving ICI therapy. In a subgroup analysis, the negative correlation of PPI use with ICI efficacy was significant in patients with non-small cell lung cancer [PFS, HR = 1.27 (1.10-1.47)] and urothelial carcinoma [OS, HR = 1.55 (1.31-1.84), PFS, HR = 1.52 (1.13-2.06)] and mixed cohorts containing multiple cancer types [OS, HR = 1.40 (1.16-1.69)], while an opposite result was observed in the PFS of patients with melanoma [HR = 0.48 (0.25-0.90)]. Moreover, the unfavorable prognostic impact of PPI use was also significant in patients over 65 years old [OS, HR = 1.28 (1.05-1.55), PFS, HR = 1.32 (1.12-1.56)] or those receiving anti-PD-1 [OS, HR = 1.37 (1.04-1.79)] or anti-PD-L1 therapies (OS, HR = 1.49 (1.30-1.69), PFS, HR = 1.34 (1.20-1.50). Finally, PPI use was significantly correlated with a worse prognosis in patients receiving PPIs 30 days before and/or after ICI initiation (OS, HR = 1.38 (1.18-1.62), PFS, HR = 1.23 (1.06-1.43)).

Conclusion

Although our global analysis revealed PPI use was not correlated with the PFS of ICI-treated patients, considering the results of our subgroup analysis, PPIs should be still cautiously used shortly before or during ICI therapy. Furthermore, more clinical validations and related mechanism investigations are of great necessity to clarify the clinical correlation of PPI use with ICI efficacy.

Systematic Review Registration

[https://www.crd.york.ac.uk/prospero/], PROSPERO [No. CRD42021243707].

PI3K inhibitor 3-MA promotes the antiproliferative activity of esomeprazole in gastric cancer cells by downregulating EGFR via the PI3K/FOXO3a pathway

Gastric cancer is a common gastrointestinal malignancy worldwide, with a high mortality rate and poor prognosis. Esomeprazole (ESO) has been shown to have anticancer activity by affecting cell growth and autophagy and its mechanism in gastric cancer cells is evident. The PI3K/AKT/FOXO3a pathway is central in cancers. 3-Methyladenine (3-MA), a dual inhibitor of PI3K and autophagy, plays a synergistic role in combination with antitumor agents. In this study, we assessed the role of ESO on the PI3K/AKT/FOXO3a pathway and the beneficial effects of ESO combined with 3-MA in gastric cancer cells. Cell viability, proliferation, invasion, migration, apoptosis, autophagy, and protein expression were detected by CCK-8, EdU, Transwell, flow cytometry, immunofluorescence assay, and western blot. ESO decreased cell viability in a concentration- and time-dependent manner and increased autophagy with upregulation of LC3II and P62. Additionally, ESO inhibited the proliferation, migration, and invasion and induced the apoptosis of gastric cancer cells in a concentration-dependent manner. ESO inhibited PI3K/AKT/FOXO3a signaling and EGFR and SKP2 expression concentration-dependent. 3-MA enhanced the antiproliferative activity of ESO and synergistically inhibited PI3K/FOXO3a signaling and the expression of EGFR but not SKP2. Furthermore, pretreatment with the EGFR inhibitor AG1478 enhanced the antiproliferative activity of ESO in gastric cancer cells. In conclusion, our results suggested that the PI3K inhibitor 3-MA promotes the antiproliferative activity of ESO in gastric cancer cells by synergistically downregulating EGFR via the PI3K/FOXO3a pathway.

Esomeprazole enhances the effect of ionizing radiation to improve tumor control

The resistance of cancer cells to radiation-based treatment is a major clinical challenge confounding standard of care in cancer. This problem is particularly notable in many solid tumors where cancer cells are only partially responsive to radiation therapy. Combination of radiation with radiosensitizers is able to enhance tumor cell killing. However, currently available radiosensitizers are associated with significant normal tissue toxicity. Accordingly, there is an unmet need to develop safer and more effective radiosensitizers to improve tumor control. Here, we evaluated the radiosensitizing effect of the FDA-approved drug esomeprazole in normal and radioresistant human head and neck squamous cell carcinoma (HNSCC) cells in vitro, and in a mouse model of HNSCC. For the in vitro studies, we used cancer cell colony formation (clonogenicity) assay to compare cancer cell growth in the absence or presence of esomeprazole. To determine mechanism(s) of action, we assessed cell proliferation and profiled cell cycle regulatory proteins. In addition, we performed reverse phase protein array (RPPA) study to understand the global effect of esomeprazole on over 200 cancer-related proteins. For the in vivo study, we engrafted HNSCC in a mouse model and compared tumor growth in animals treated with radiation, esomeprazole, and combination of radiation with esomeprazole. We found that esomeprazole inhibits tumor growth and dose-dependently enhances the cell killing effect of ionizing radiation in wildtype and p53-mutant radioresistant cancer cells. Mechanistic studies demonstrate that esomeprazole arrests cancer cells in the G1 phase of the cell cycle through upregulation of p21 protein and inhibition of cyclin-dependent kinases (Cdks) type 1 (Cdk1) and type 2 (Cdk2). In vivo data showed greater tumor control in animals treated with combination of radiation and esomeprazole compared to either treatment alone, and that this was associated with inhibition of cell proliferation in vivo. In addition, combination of esomeprazole with radiation significantly impaired repair following radiation-induced DNA damage. Our studies indicate that esomeprazole sensitizes cancer cells to ionizing radiation, and is associated with upregulation of p21 to arrest cells in the G1 phase of the cell cycle. Our findings have significant therapeutic implications for the repurposing of esomeprazole as a radiosensitizer in HNSCC and other solid tumors.

Linking Tumor Microenvironment to Plasticity of Cancer Stem Cells: Mechanisms and Application in Cancer Therapy

Cancer stem cells (CSCs) are a minority subset of cancer cells that can drive tumor initiation, promote tumor progression, and induce drug resistance. CSCs are difficult to eliminate by conventional therapies and eventually mediate tumor relapse and metastasis. Moreover, recent studies have shown that CSCs display plasticity that renders them to alter their phenotype and function. Consequently, the varied phenotypes result in varied tumorigenesis, dissemination, and drug-resistance potential, thereby adding to the complexity of tumor heterogeneity and further challenging clinical management of cancers. In recent years, tumor microenvironment (TME) has become a hotspot in cancer research owing to its successful application in clinical tumor immunotherapy. Notably, emerging evidence shows that the TME is involved in regulating CSC plasticity. TME can activate stemness pathways and promote immune escape through cytokines and exosomes secreted by immune cells or stromal cells, thereby inducing non-CSCs to acquire CSC properties and increasing CSC plasticity. However, the relationship between TME and plasticity of CSCs remains poorly understood. In this review, we discuss the emerging investigations on TME and CSC plasticity to illustrate the underlying mechanisms and potential implications in suppressing cancer progression and drug resistance. We consider that this review can help develop novel therapeutic strategies by taking into account the interlink between TME and CSC plasticity.

Xanthenylacetic Acid Derivatives Effectively Target Lysophosphatidic Acid Receptor 6 to Inhibit Hepatocellular Carcinoma Cell Growth

Despite the increasing incidence of hepatocellular carcinoma (HCC) worldwide, current pharmacological treatments are still unsatisfactory. We have previously shown that lysophosphatidic acid receptor 6 (LPAR6) supports HCC growth and that 9-xanthenylacetic acid (XAA) acts as an LPAR6 antagonist inhibiting HCC growth without toxicity. Here, we synthesized four novel XAA derivatives, (±)-2-(9H-xanthen-9-yl)propanoic acid (compound 4 - MC9), (±)-2-(9H-xanthen-9-yl)butanoic acid (compound 5 - MC6), (±)-2-(9H-xanthen-9-yl)hexanoic acid (compound 7 - MC11), and (±)-2-(9H-xanthen-9-yl)octanoic acid (compound 8 - MC12, sodium salt) by introducing alkyl groups of increasing length at the acetic α-carbon atom. Two of these compounds were characterized by X-ray powder diffraction and quantum mechanical calculations, while molecular docking simulations suggested their enantioselectivity for LPAR6. Biological data showed anti-HCC activity for all XAA derivatives, with the maximum effect observed for MC11. Our findings support the view that increasing the length of the alkyl group improves the inhibitory action of XAA and that enantioselectivity can be exploited for designing novel and more effective XAA-based LPAR6 antagonists.

New hypotheses for cancer generation and progression

Since Nixon famously declared war on cancer in 1971, trillions of dollars have been spent on cancer research but the life expectancy for most forms of cancer is still poor. There are many reasons for the partial success of cancer translational research. One of these can be the predominance of certain paradigms that potentially narrowed the vision in interpreting cancer. The main paradigm to explain carcinogenesis is based on DNA mutations, which is well interpreted by the somatic mutation theory (SMT). However, a different theory claims that cancer is instead a tissue disease as proposed by the Tissue Organization Field Theory (TOFT). Here, we propose new hypotheses to explain the origin and pathogenesis of cancer. In this perspective, the systemic-evolutionary theory of cancer (SETOC) is discussed as well as how the microenvironment affects the adaptation of transformed cells and the reversion to a unicellular-like or embryo-like phenotype.

Treatment of liver cancer cells with ethyl acetate extract of Crithmum maritimum permits reducing sorafenib dose and toxicity maintaining its efficacy

OBJECTIVES

Hepatocellular carcinoma (HCC) is one of the most frequent tumours worldwide and available drugs are inadequate for therapeutic results and tolerability. Hence, novel effective therapeutic tools with fewer side effects are of paramount importance. We have previously shown that Crithmum maritimum ethyl acetate extract exerts a cytostatic effect in HCC cells. Here, we tested whether C. maritimum ethyl acetate extract in combination with half sorafenib IC50 dose ameliorated efficacy and toxicity of sorafenib in inhibiting liver cancer cell growth. Moreover, we investigated the mechanisms involved.

METHODS

Two HCC cell lines (Huh7 and HepG2) were treated with C. maritimum ethyl acetate extract and half IC50 sorafenib dose usually employed in vitro. Then, cell proliferation, growth kinetics and cell toxicity were analysed together with an investigation of the cellular mechanisms involved, focusing on cell cycle regulation and apoptosis.

KEY FINDINGS

Results show that combined treatment with C. maritimum ethyl acetate extract and half IC50 sorafenib dose decreased cell proliferation comparably to full-dose sorafenib without increasing cell toxicity as confirmed by the effect on cell cycle regulation and apoptosis.

CONCLUSIONS

These results provide scientific support for the possibility of an effective integrative therapeutic approach for HCC with fewer side effects on patients.

Use of omeprazole, the proton pump inhibitor, as a potential therapy for the capecitabine-induced hand-foot syndrome

Hand-foot syndrome (HFS), also known as palmar-plantar erythrodysesthesia (PPE), is a major side effect of capecitabine. Although the pathogenesis of HFS remains unknown, some studies suggested a potential involvement of inflammation in its pathogenesis. Proton pump inhibitors (PPIs) have been reported to have anti-inflammatory effects. In this study, we investigated the ameliorative effects of omeprazole, a PPI on capecitabine-related HFS in mice model, and a real-world database. Repeated administration of capecitabine (200 mg/kg, p.o., five times a week for 3 weeks) increased fluid content, redness, and tumor necrosis factor (TNF)-α substance of the mice hind paw. Co-administration of omeprazole (20 mg/kg, p.o., at the same schedule) significantly inhibited these changes induced by capecitabine. Moreover, based on the clinical database analysis of the Food and Drug Administration Adverse Event Reporting System, the group that has used any PPIs had a lower reporting rate of capecitabine-related PPE than the group that has not used any PPIs. (6.25% vs. 8.31%, p < 0.0001, reporting odds ratio (ROR) 0.74, 95% confidence interval (CI) 0.65-0.83). Our results suggest that omeprazole may be a potential prophylactic agent for capecitabine-induced HFS.

Inhibition of LDH-A by Oxamate Enhances the Efficacy of Anti-PD-1 Treatment in an NSCLC Humanized Mouse Model

Immunotherapy is a curable treatment for certain cancers, but it is still only effective in a small subset of patients, partly because of the lack of sufficient immune cells in the tumor. It is reported that targeted lactate dehydrogenase (LDH) to reduce lactic acid production can promote the infiltration and activity of immune cells and turn tumors into hot tumors. Therefore, we constructed a humanized mouse model to evaluate the efficacy of using classical LDH inhibitor oxamate and pembrolizumab alone or in combination in non-small cell lung cancer (NSCLC). We found that both oxamate and pembrolizumab monotherapy significantly delayed tumor growth; moreover, combination therapy showed better results. Immunofluorescence analysis showed that oxamate treatment increased the infiltration of activated CD8+ T cells in the tumor, which might have enhanced the therapeutic effects of pembrolizumab. Treatment of the humanized mice with anti-CD8 abrogated the therapeutic effects of oxamate, indicating CD8+ T cells as the main force mediating the effect of oxamate. In conclusion, Our preclinical findings position that oxamate not only inhibits tumor growth at a high safe dose but also enhances the efficacy of pembrolizumab in Hu-PBMC-CDX mice. Our study also provides a preclinical model for exploring the efficacy of other immune-based combination therapies for NSCLC.

Environmental control of mammary carcinoma cell expansion by acidification and spheroid formation in vitro

Breast cancer is the leading cause of cancer death among women worldwide. Like other cancers, mammary carcinoma progression involves acidification of the tumor microenvironment, which is an important factor for cancer detection and treatment strategies. However, the effects of acidity on mammary carcinoma cell morphology and phenotype have not been thoroughly characterized. Here, we evaluated fundamental effects of environmental acidification on mammary carcinoma cells in standard two-dimensional cultures and three-dimensional spheroids. Acidification decreased overall mammary carcinoma cell viability, while increasing their resistance to the anthracycline doxorubicin. Environmental acidification also increased extracellular vesicle production by mammary carcinoma cells. Conditioned media containing these vesicles appeared to increase fibroblast motility. Acidification also increased mammary carcinoma cell motility when cultured with fibroblasts in spheroids. Taken together, results from this study suggest that environmental acidification induces drug resistance and extracellular vesicle production by mammary carcinoma cells that promote tumor expansion.

Combination Therapy of High-Dose Rabeprazole Plus Metronomic Capecitabine in Advanced Gastro-Intestinal Cancer: A Randomized Phase II Trial

Simple Summary

This is the first phase II study of high dose rabeprazole repurposing (1.5 mg/kg bid, three days a week) combined with metronomic capecitabine (mCAP), 1500 mg/daily, in gastrointestinal cancer, aimed at evaluating the activity and safety of high-dose proton pump inhibitor in combination with mCAP as salvage treatment in pretreated patients. A 3-months PFS rate of 66% and 57% was reported in the mCAP-rabeprazole and mCAP group, respectively. Although, the adjunct of high dose rabeprazole to mCAP did not improve mCAP activity, the combination of proton pump inhibitor with chemotherapy would deserve to be further investigated.

Abstract

Background: In recent years, proton pump inhibitors (PPIs) have been investigated at high-dose to modulate tumor microenvironment acidification thus restoring chemotherapeutic sensitivity. This is the first trial to study activity and safety of repurposing high dose rabeprazole combined with metronomic capecitabine (mCAP). Methods: A phase II study in which patients with gastrointestinal cancer, refractory to standard treatments, who had a life expectancy >3 months, were blind randomized 1:1 to mCAP, 1500 mg/daily, continuously with or without rabeprazole 1.5 mg/kg bid, three days a week. The primary endpoint was 3-months progression-free survival (PFS). The secondary endpoints were clinical benefit (CB) and overall survival (OS). Safety and plasma concentrations of capecitabine and its metabolites (5′-DFUR and 5-FU) were also evaluated. Results: Sixty-seven (median age 69 years; 63% male; 84% colorectal cancer, 76% ECOG-PS ≤ 1; 84% pretreated with two or more lines of chemotherapy) out of 90 patients screened for eligibility, were randomized to receive mCAP+rabeprazole (n = 32) vs. mCAP (n = 35). All patients were evaluable for response. No significant difference between mCAP+rabeprazole vs. mCAP, in terms of 3-months PFS rate (HR = 1.43, 95%CI 0.53–3.85; p = 0.477), median PFS (HR = 1.22, 95%CI 0.75–2.00, p = 0.420), CB (RR = 0.85, 95%CI 0.29–2.44; p = 0.786) and median OS (HR = 0.89, 95%CI 0.54–1.48; p = 0.664) was observed. However, a 3-year OS rate of 10% and 12% was reported in the mCAP-rabeprazole and mCAP groups, respectively. Overall, no grade 3 or 4 toxicity occurred but grade 1 or 2 adverse event of any type were more frequently in the mCAP+rabeprazole group than in the mCAP (OR 2.83, 95%CI 1.03–7.79; p = 0.043). Finally, there was not statistically significant difference in the plasma concentration of capecitabine and its metabolites between the two groups. Conclusions: Although the adjunct of high dose rabeprazole to mCAP was not shown to affect mCAP activity, as PPI are being investigated worldwide as drugs to be repositioned in cancer treatment and also considering the limited sample size as well as the favorable safety profile of the combination in the present study, further clinical investigations are desirable.

Macrolide antibiotics enhance the antitumor effect of lansoprazole resulting in lysosomal membrane permeabilization‑associated cell death

The proton pump inhibitor lansoprazole (LPZ) inhibits the growth of several cancer cell lines, including A549 and CAL 27. We previously reported that macrolide antibiotics such as azithromycin (AZM) and clarithromycin (CAM) potently inhibit autophagic flux and that combining AZM or CAM with the epidermal growth factor receptor inhibitors enhanced their antitumor effect against various cancer cells. In the present study, we conducted the combination treatment with LPZ and macrolide antibiotics against A549 and CAL 27 cells and evaluated cytotoxicity and morphological changes using cell proliferation and viability assays, flow cytometric analysis, immunoblotting, and morphological assessment. Combination therapy with LPZ and AZM greatly enhanced LPZ-induced cell death, whereas treatment with AZM alone exhibited negligible cytotoxicity. The observed cytotoxic effect was not mediated through apoptosis or necroptosis. Transmission electron microscopy of A549 cells treated with the LPZ + AZM combination revealed morphological changes associated with necrosis and accumulated autolysosomes with undigested contents. Furthermore, the A549 cell line with ATG5 knockout exhibited complete inhibition of autophagosome formation, which did not affect LPZ + AZM treatment-induced cytotoxicity, thus excluding the involvement of autophagy-dependent cell death in LPZ + AZM treatment-induced cell death. A549 cells treated with LPZ + AZM combination therapy retained the endosomal Alexa-dextran for extended duration as compared to untreated control cells, thus indicating impairment of lysosomal digestion. Notably, lysosomal galectin-3 puncta expression induced due to lysosomal membrane permeabilization was increased in cells treated with LPZ + AZM combination as compared to the treatment by either agent alone. Collectively, the present results revealed AZM-induced autolysosome accumulation, potentiated LPZ-mediated necrosis, and lysosomal membrane permeabilization, thus suggesting the potential clinical application of LPZ + AZM combination therapy for cancer treatment.

Towards an Integral Therapeutic Protocol for Breast Cancer Based upon the New H+-Centered Anticancer Paradigm of the Late Post-Warburg Era

A brand new approach to the understanding of breast cancer (BC) is urgently needed. In this contribution, the etiology, pathogenesis, and treatment of this disease is approached from the new pH-centric anticancer paradigm. Only this unitarian perspective, based upon the hydrogen ion (H+) dynamics of cancer, allows for the understanding and integration of the many dualisms, confusions, and paradoxes of the disease. The new H+-related, wide-ranging model can embrace, from a unique perspective, the many aspects of the disease and, at the same time, therapeutically interfere with most, if not all, of the hallmarks of cancer known to date. The pH-related armamentarium available for the treatment of BC reviewed here may be beneficial for all types and stages of the disease. In this vein, we have attempted a megasynthesis of traditional and new knowledge in the different areas of breast cancer research and treatment based upon the wide-ranging approach afforded by the hydrogen ion dynamics of cancer. The concerted utilization of the pH-related drugs that are available nowadays for the treatment of breast cancer is advanced.

Gastrointestinal pharmacology: practical tips for the esophagologist

Gastroesophageal reflux disease (GERD) is primarily a motor disorder, and its pathogenesis is multifactorial. As a consequence, treatment should be able to address the underlying pathophysiology. Proton pump inhibitors (PPIs) are the mainstay of medical therapy for GERD, but these drugs only provide the control of symptoms and lesions without curing the disease. However, continuous acid suppression with PPIs is recommended for patients with Barrett's esophagus because of their potential chemopreventive effects. In addition to the antisecretory activity, these compounds display several pharmacological properties, often overlooked in clinical practice. PPIs can indeed affect gastric motility, exert a mucosal protective effect, and an antioxidant, anti-inflammatory, and antineoplastic activity, also protecting cancer cells from developing chemo- or radiotherapeutic resistance. Even in the third millennium, current pharmacologic approaches to address GERD are limited. Reflux inhibitors represent a promise unfulfilled, effective and safe prokinetics are lacking, and antidepressants, despite being effective in selected patients, give rise to adverse events in a large proportion of them. While waiting for new drug classes (like potassium-competitive acid blockers), reassessing old drugs (namely alginate-containing formulations), and paving the new avenue of esophageal mucosal protection are, at the present time, the only reliable alternatives to acid suppression.

The Interplay of Dysregulated pH and Electrolyte Imbalance in Cancer

Cancer cells and tissues have an aberrant regulation of hydrogen ion dynamics driven by a combination of poor vascular perfusion, regional hypoxia, and increased the flux of carbons through fermentative glycolysis. This leads to extracellular acidosis and intracellular alkalinization. Dysregulated pH dynamics influence cancer cell biology, from cell transformation and tumorigenesis to proliferation, local growth, invasion, and metastasis. Moreover, this dysregulated intracellular pH (pHi) drives a metabolic shift to increased aerobic glycolysis and reduced mitochondrial oxidative phosphorylation, referred to as the Warburg effect, or Warburg metabolism, which is a selective feature of cancer. This metabolic reprogramming confers a thermodynamic advantage on cancer cells and tissues by protecting them against oxidative stress, enhancing their resistance to hypoxia, and allowing a rapid conversion of nutrients into biomass to enable cell proliferation. Indeed, most cancers have increased glucose uptake and lactic acid production. Furthermore, cancer cells have very dysregulated electrolyte balances, and in the interaction of the pH dynamics with electrolyte, dynamics is less well known. In this review, we highlight the interconnected roles of dysregulated pH dynamics and electrolytes imbalance in cancer initiation, progression, adaptation, and in determining the programming and reprogramming of tumor cell metabolism.