Pioglitazone Use and Risk of Bladder Cancer: an In Vitro Study

A Scoping Review of the Use of Pioglitazone in the Treatment of Temporo-Mandibular Joint Arthritis

Thiazolidinediones (TZDs) are a group of diabetes medications currently being investigated for anti-arthritis effectiveness, one of which is pioglitazone. The purpose of this scoping review is to evaluate the potential use of pioglitazone in the treatment of temporomandibular joint (TMJ) arthritis. The criteria of eligibility were studies with the diagnosis of arthritis and pioglitazone treatment with a change in any inflammation index as an outcome. Of the 1169 records initially identified following the selection process, two animal studies and four clinical studies were included in the review. Improvements from the baseline were observed in each treatment group for each inflammation indicator. The results of the animal studies on the temporomandibular joints and on patients with rheumatoid and psoriatic arthritis indicate that the drug in question may have potential to treat arthritis, including within the temporomandibular joint.

Pioglitazone, Bladder Cancer and the Presumption of Innocence

BACKGROUND

Thiazolidinediones are potent exogenous agonists of PPAR-γ, which augment the effects of insulin to its cellular targets and mainly at the level of adipose tissue. Pioglitazone, the main thiazolidinedione in clinical practice, has shown cardiovascular and renal benefits in patients with type 2 diabetes, durable reduction of glycated hemoglobulin levels, important improvements of several components of the metabolic syndrome and beneficial effects of non-alcoholic fatty liver disease.

OBJECTIVE

Despite all of its established advantages, the controversy for an increased risk of developing bladder cancer, combined with the advent of newer drug classes that achieved major cardiorenal effects have significantly limited its use spreading a persistent shadow of doubt for its future role.

METHODS

Pubmed, Google and Scope databases have been thoroughly searched and relevant studies were selected.

RESULTS

This paper explores thoroughly both in vitro and in vivo (animal models and humans) studies that investigated the possible association of pioglitazone with bladder cancer.

CONCLUSION

Currently the association of pioglitazone with bladder cancer cannot be based on solid evidence. This evidence cannot justify its low clinical administration, especially in the present era of individualised treatment strategies. Definite clarification of this issue is imperative and urgently anticipated from future high quality and rigorous pharmacoepidemiologic research, keeping in mind its unique mechanism of action and its significant pleiotropic effects.

PPAR-γ Modulators as Current and Potential Cancer Treatments

Worldwide, cancer has become one of the leading causes of mortality. Peroxisome Proliferator-Activated Receptors (PPARs) is a family of critical sensors of lipids as well as regulators of diverse metabolic pathways. They are also equipped with the capability to promote eNOS activation, regulate immunity and inflammation response. Aside from the established properties, emerging discoveries are also made in PPAR's functions in the cancer field. All considerations are given, there exists great potential in PPAR modulators which may hold in the management of cancers. In particular, PPAR-γ, the most expressed subtype in adipose tissues with two isoforms of different tissue distribution, has been proven to be able to inhibit cell proliferation, induce cell cycle termination and apoptosis of multiple cancer cells, promote intercellular adhesion, and cripple the inflamed state of tumor microenvironment, both on transcriptional and protein level. However, despite the multi-functionalities, the safety of PPAR-γ modulators is still of clinical concern in terms of dosage, drug interactions, cancer types and stages, etc. This review aims to consolidate the functions of PPAR-γ, the current and potential applications of PPAR-γ modulators, and the challenges in applying PPAR-γ modulators to cancer treatment, in both laboratory and clinical settings. We sincerely hope to provide a comprehensive perspective on the prospect of PPAR-γ applicability in the field of cancer treatment.

Increased DNA strand breaks and neoplastic transformation in human bladder cells treated with pioglitazone

Pioglitazone (PIO), an oral hypoglycemic agent, is used in the treatment of type 2 diabetes. Some studies have suggested that an increased risk of bladder cancer with PIO exposure, while the others reported there is no such relationship. Therefore, it is doubtful whether PIO can increase the risk of bladder cancer. The effects of PIO on DNA damage and/or transformation of human bladder cells are not fully known. We investigated the effects of PIO on cytotoxicity, DNA single and double strand breaks and repair and neoplastic transformation in human bladder cells (hTU1) treated with 10, 20, and 40 μM PIO for 24, 48 and 72 hr. PIO decreased cell viability in a concentration-dependent manner. Increased levels of comet parameters showed that PIO and its metabolites can significantly induce DNA double strand breaks at all concentrations tested. PIO also significantly induced the formation of phosphorylated H2AX and p53 binding protein 1 foci. DNA damage was not repaired in a 24 hr recovery period. PIO can also induce malignant transformation of human bladder cells exhibiting loss of contact inhibition and anchorage independent growth. This is the first study to indicate that PIO can induce DNA damage and malignant transformation, reduce or alter the DNA repair capacity in human bladder cells. From these results, we suggest that patients with diabetes treated with PIO may have an increased risk of bladder cancer.

The role and function of PPARγ in bladder cancer

Peroxisome proliferator-activated receptor gamma (PPARγ), a member of the nuclear receptor superfamily, participates in multiple physiological and pathological processes. Extensive studies have revealed the relationship between PPARγ and various tumors. However, the expression and function of PPARγ in bladder cancer seem to be controversial. It has been demonstrated that PPARγ affects the occurrence and progression of bladder cancer by regulating proliferation, apoptosis, metastasis, and reactive oxygen species (ROS) and lipid metabolism, probably through PPARγ-SIRT1 feedback loops, the PI3K-Akt signaling pathway, and the WNT/β-catenin signaling pathway. Considering the frequent relapses after chemotherapy, some researchers have focused on the relationship between PPARγ and chemotherapy sensitivity in bladder cancer. Moreover, the feasibility of PPARγ ligands as potential therapeutic targets for bladder cancer has been uncovered. Taken together, this review summarizes the relevant literature and our findings to explore the complicated role and function of PPARγ in bladder cancer.

Pioglitazone Alters the Proteomes of Normal Bladder Epithelial Cells but Shows No Tumorigenic Effects

PURPOSE

Pioglitazone, an antihyperglycemic drug, is widely used in diabetes mellitus patients with insulin resistance. Although pioglitazone is known to have a potential link to bladder cancer (BC), there have been contradictory results. This present study is designed to understand the regulatory mechanisms that drive the effects of pioglitazone on the bladder epithelial cells.

METHODS

Labeled liquid chromatography-tandem mass spectrometry-based proteomics profiling characterized the global proteomes of normal human bladder epithelial cells treated with or without pioglitazone.

RESULTS

This approach detected approximately 5,769 proteins in total. Of those 5,769 proteins, 124 were identified as being differentially expressed due to pioglitazone treatment. Further analysis identified 95 upregulated and 29 downregulated proteins (absolute log2 fold change >0.58 and P-value<0.05). The following functional gene enrichment analysis suggested that pioglitazone may be altering a few select biological processes, such as gene/chromatin silencing, by downregulating BMI1 (B lymphoma Mo-MLV insertion region 1 homolog), a polycomb complex protein. Further cell-based assays showed that cell adhesion molecules, epithelial-mesenchymal transition markers, and major signaling pathways were significantly downregulated by pioglitazone treatment.

CONCLUSION

These experimental results revealed the proteomic and biological alterations that occur in normal bladder cells in response to pioglitazone. These findings provided a landscape how bladder proteome is influenced by pioglitazone, which suggests the potential adverse effects of diabetes drugs and their links to bladder dysfunctions.

Proteomics profiling of epithelium-derived exosomes from nasal polyps revealed signaling functions affecting cellular proliferation

BACKGROUND

Nasal polyps are a significantly associated pathology of chronic rhinosinusitis (CRS) whose mechanisms of pathogenesis are not fully elucidated, especially the interaction of the polyp with its environment that allows its growth on the nasal epithelial lining. Exosomes are nanovesicles that serve important biological functions, including cell-to-cell signaling and communication.

OBJECTIVE

Hence, we sought to explore the roles of the epithelial-derived exosomal proteome obtained from the human nasal epithelium in the modulation of CRS with nasal polyp (CRSwNP) pathogenesis.

METHODS

We sampled exosomes from nasal lavage fluid and primary human nasal epithelial cells (hNECs) from healthy controls and patients with CRSwNP with and without coexisting asthma. The presence of exosomes was confirmed using a NanoSight assay, transmission electron microscopy and western blotting. The exosomal proteome was profiled with mass spectrometry. The Cell Counting Kit-8 was used to confirm the roles of exosomes in mediating cellular proliferation.

RESULTS

The hNEC-derived exosomes from diseased epithelium contained differentially expressed proteins that were mainly involved in epithelial remodeling via pathways such as p53. An in vitro study further demonstrated that epithelial-derived exosomes from patients with CRSwNP (with and without coexisting asthma) significantly reduced the rate of proliferation of control hNECs at an effective concentration of ≥10 μg/ml.

CONCLUSIONS

Exosomes secreted by hNECs from patients with CRSwNP, regardless of their coexistence with asthma, are laden with proteins that influence cell proliferation pathways, potentially leading to remodeling of the sinonasal mucosa.

Importance of PNO1 for growth and survival of urinary bladder carcinoma: Role in core-regulatory circuitry

PNO1 (partner of Nob1) was known as a RNA‐binding protein in humans, and its ortholog PNO1 was reported to participate ribosome and proteasome biogenesis in yeasts. Yet there have been few studies about its functions in mammalian cells, and so far its role in human cells has never been reported, especially in urinary bladder cancer (UBC).We interrogated the cellular functions and clinical significance of PNO1 in, and its molecular mechanism through microarrays and bioinformatics analysis. Our findings support that PNO1 participates in promoting proliferation and colonogenesis, while reducing apoptosis of UBC cells, and is also predicted to be associated with the migration and metastasis of UBC PNO1 knockdown (KD) attenuated the tumorigenesis ability of UBC in mouse. PNO1 KD led to the altered expression of 1543 genes that are involved in a number of signalling pathways, biological functions and regulation networks. CD44, PTGS2, cyclin D1, CDK1, IL‐8, FRA1, as well as mTOR, p70 S6 kinase, p38 and Caspase‐3 proteins were all down‐regulated in PNO1 KD cells, suggesting the involvement of PNO1 in inflammatory responses, cell cycle regulation, chemotaxis, cell growth and proliferation, apoptosis, cell migration and invasiveness. This study will enhance our understanding of the molecular mechanism of UBC and may eventually provide novel targets for individualized cancer therapy.

Functional network analysis of gene-phenotype connectivity based on pioglitazone

Pioglitazone, a type of insulin sensitizer, serves as an effective anti-hyperglycemic drug. The mechanism of action of pioglitazone is through the activation of the peroxisome proliferator-activated receptor (PPAR), which results in enhanced insulin sensitivity of peripheral tissues and the liver, causing a reduction in the production and output of liver sugar. It has been reported that pioglitazone increases the risk of bladder cancer, but the underlying mechanisms have remained elusive. It was hypothesized that modulation of pioglitazone activity may be predicted by systematically analyzing data published on drugs. This hypothesis was tested by querying the Drug-Target Interactome (DTome), a web-based tool that provides open-source data from three databases (DrugBank, PharmGSK and Protein Interaction Network analysis). A total of 4 direct target proteins (DTPs) and further DTP-associated genes were identified for pioglitazone. Subsequently, an enrichment analysis was performed for all DTP-associated genes using Cytoscape software. A total of 12 Kyoto Encyclopedia of Genes and Genomes pathways were identified, including the 'PPAR signaling pathway' as well as 'pathways in cancer' as relevant pathways. Functional network analysis was able to identify direct and indirect target genes of pioglitazone, resulting in a list of possible biological functions based on published databases. Furthermore, Kaplan-Meier analysis indicated that pioglitazone may affect the survival rate of patients with bladder cancer through genetic alterations (missense mutation, truncating mutation, amplification, deep deletion and fusion) of target genes. Therefore, it should be used with caution.

Global Versus Indian Perspective of Pioglitazone-induced Adverse Drug Reactions Including Bladder Cancer: A Comparative Retrospective Pharmacovigilance Analysis

PURPOSE

In 2011, France and Germany banned pioglitazone due to a concomitant risk for bladder cancer. There has been continued debate about this topic. Therefore, we present a detailed analysis of data from individual case safety reports of pioglitazone use (PG-ICSRs) associated with bladder cancer reported worldwide and in India.

METHODS

Data from PG-ICSRs reported by the National Coordination Centre's Pharmacovigilance Programme of India, as well as over 131 World Health Organization member countries in the Uppsala Monitoring Centre's VigiLyze pharmacovigilance database system, from January 1, 1967, to March 4, 2018, were collected. Comparisons between data from global and Indian PG-ICSRs were made by applying filters such as country, bladder cancer, age group, gender, time period, information component, and data mining.

FINDINGS

Among the adverse drug reactions (ADRs) reported with pioglitazone use worldwide, bladder cancer and related terms were the most highly reported (43%). The most frequently co-reported concurrently used drug was metformin, which was included in 25% and 40% of overall and bladder cancer-specific PG-ICSRs, respectively. Suspected bladder cancer-specific pioglitazone-related reactions were reported in 27 countries, with 8548 serious and 1858 fatal cases and an information components value of 9.15. The Americas had the highest relative percentage of suspected bladder cancer in PG-ICSRs (53%), while the prevalence was much lower in India (2%). In both cohorts, men over the age of 45 years constituted the most highly reported population.

IMPLICATIONS

India has a very low prevalence of reported overall and bladder cancer-specific pioglitazone-related ADRs compared to Europe and the Americas. Possible explanations for the difference in reporting rates include variance in genetic makeup, low BC risk factor, pioglitazone prescription at a lower therapeutic dose, greater use of chemopreventive spices in the diet, higher frequency of metformin as a concurrent drug, and under-reporting of ADRs.

High Glucose with Insulin Induces Cell Cycle Progression and Activation of Oncogenic Signaling of Bladder Epithelial Cells Cotreated with Metformin and Pioglitazone

Metformin and pioglitazone are two commonly prescribed oral hypoglycemic agents for diabetes. Recent evidence suggests that these drugs may contribute to bladder cancer. This study investigated molecular mechanism underlying effects of metformin and pioglitazone in bladder epithelial carcinogenesis in type 2 diabetes. The cells derived from human bladder epithelial cells (HBlEpCs) were treated with metformin or pioglitazone with high glucose and insulin. Cell viability and proliferation were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and a bromodeoxyuridine incorporation assay, respectively, while cell cycle regulatory factors and oncogene expression were analyzed using western blotting. Metformin or pioglitazone suppressed cell viability concentration and time dependently, which was reversed by exposure to high glucose with or without insulin. Prolonged exposure to high glucose and insulin enhanced cyclin D, cyclin-dependent kinase 4 (Cdk4), and Cdk2 expression and suppressed cyclin-dependent kinase inhibitors p21 and p15/16 in HBlEpC cotreated with pioglitazone and metformin. Levels of tumor suppressor proteins p53 and cav-1 were downregulated while those of the oncogenic protein as c-Myc were upregulated under high glucose and insulin supplementation in HBlEpC cotreated with pioglitazone and metformin. Prolonged exposure to high glucose with or without insulin downregulated B cell lymphoma 2-associated X (Bax) and failed to enhance the expression of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK) in drug-treated cells. These results suggest that hyperglycemic and insulinemic conditions promote cell cycle progression and oncogenic signaling in drug-treated bladder epithelial cells and uncontrolled hyperglycemia and hyperinsulinemia are probably greater cancer risk factors than diabetes drugs.