Double benefit of metformin treatment: improved bladder function in cyclophosphamide-induced cystitis and enhanced cytotoxicity in cancer cells

Mechanisms underlying dose-limiting toxicities of conventional chemotherapeutic agents

Dose-limiting toxicities (DLTs) are severe adverse effects that define the maximum tolerated dose of a cancer drug. In addition to the specific mechanisms of each drug, common contributing factors include inflammation, apoptosis, ion imbalances, and tissue-specific enzyme deficiencies. Among various DLTs are bleomycin-induced pulmonary fibrosis, doxorubicin-induced cardiomyopathy, cisplatin-induced nephrotoxicity, methotrexate-induced hepatotoxicity, vincristine-induced neurotoxicity, paclitaxel-induced peripheral neuropathy, and irinotecan, which elicits severe diarrhea. Currently, specific treatments beyond dose reduction are lacking for most toxicities. Further research on cellular and molecular pathways is imperative to improve their management. This review synthesizes preclinical and clinical data on the pharmacological mechanisms underlying DLTs and explores possible treatment approaches. A comprehensive perspective reveals knowledge gaps and emphasizes the need for future studies to develop more targeted strategies for mitigating these dose-dependent adverse effects. This could allow the safer administration of fully efficacious doses to maximize patient survival.

The inhibitory effect of escitalopram on mouse detrusor contractility: The role of L-type calcium channels

Selective serotonin reuptake inhibitors (SSRIs) are associated with urinary problems attributed to their central effects. ESC is a preferred SSRI and several case reports described that ESC is related to urinary retention. However, the direct effect of ESC on detrusor contractility is still not completely elucidated. Thus, we investigated the effect of ESC on detrusor contractility and mechanism(s) of its action in isolated mouse detrusor strips. Molecular docking and measurement of intracellular calcium were performed to determine the possible calcium channel blocking effect of ESC. The contractile responses to carbachol (CCh), KCl and electrical field stimulation of detrusor strips were significantly abolished by ESC (10 or 100 μM). ESC relaxed KCl-precontracted detrusor strips concentration-dependently, which was not affected by tetraethylammonium, glibenclamide, 4-aminopyridine, propranolol, L-NAME or methylene blue. ESC (10 or 100 μM) reduced both the CaCl₂- and CCh-induced contractions under calcium-free conditions, indicating the role of calcium-involved mechanisms in ESC-mediated relaxation. Furthermore, ESC significantly decreased Bay K8644-induced contraction and the cytosolic calcium level in fura-2-loaded A7r5 cells. Molecular docking study also revealed the potential of ESC to bind L-type calcium (Ca_v1) channels. Our results demonstrate that ESC inhibits detrusor contractility via blocking Ca_v1 channels, which provides evidence for the direct effect of ESC on detrusor contractility and its mechanism.

Sulfhydryl functionalized hyaluronic acid hydrogels attenuate cyclophosphamide-induced bladder injury

Clinical management of cyclophosphamide (CYP) results in numerous side effects including hemorrhagic cystitis (HC), which is characterized by inflammation and oxidative stress damage. Intravesical hyaluronic acid (HA) supplementation, a therapeutic method to restore barrier function of bladder, avoid the stimulation of metabolic toxicants on bladder and reduce inflammatory response, has shown good results in acute or chronic bladder diseases. However, there are unmet medical needs for the treatment of HC to temporarily restore bladder barrier and reduce inflammation. Herein, sulfhydryl functionalized HA (HA-SH) and dimethyl sulfoxide (DMSO) were used to prepared a hydrogel system for optimizing the treatment of HC. We systematically evaluated the physicochemical of hydrogels and their roles in a rat model of CYP-induced HC. The prepared hydrogels exhibited outstanding gel forming properties, injectability, and biosafety. Swelling and retention studies showed that hydrogels were stable and could prolong the residence time of HA in the bladder. Histopathology and vascular permeability studies indicated that the hydrogels significantly attenuated bladder injury caused by CYP administration. Moreover, the hydrogels also showed excellent anti-inflammation and anti-oxidation properties. In conclusion, these data suggest that intravesical instillation of HA-SH/DMSO hydrogels reduces CYP-induced bladder toxicity and this work provides a new strategy for the prevention and early treatment of HC.

Trimetazidine attenuates cyclophosphamide-induced cystitis by inhibiting TLR4-mediated NFκB signaling in mice

AIM

Cyclophosphamide (CP)-induced cystitis is a challenging clinical problem involving inflammation and dysfunction of bladder. Trimetazidine (TMZ) is an anti-anginal drug with anti-oxidant and anti-inflammatory properties. We aimed to investigate the protective effects of TMZ in CP-induced cystitis via inhibiting TLR4/NFκB signaling.

MAIN METHODS

Balb/c mice were administrated TMZ (10 or 20 mg/kg/day) intraperitoneally (i.p.) for 5 consecutive days before CP. On day 6, cystitis was induced by a single dose of CP (300 mg/kg, i.p.). Mesna (2-mercaptoethane sulfonate sodium; 30 mg/kg, i.p.) was administered 20 min before and at 4 and 8 h after the CP injection. After 24 h of cystitis induction, the bladders were removed for histopathological evaluation, contractility studies, biochemical analysis and western blotting. MTT assay was performed in a cancer cell line (MDA-MB-231) to evaluate the effect of TMZ on the cytotoxicity of CP.

KEY FINDINGS

CP-induced severe cystitis was confirmed by histological disturbances and the decrease in carbachol-evoked contractions of detrusor strips, which was partially improved by TMZ (20 mg/kg/day). SOD activity and GSH content were decreased whereas TNF-α and IL-1β levels were increased in the bladders of CP-treated mice, which were restored by TMZ or mesna. TMZ reduced the CP-induced increase in the protein expressions of caspase-3, TLR4 and phosphorylated-NFκB in bladder tissues. TMZ alone decreased the cell viability and TMZ also enhanced the cytotoxicity of CP.

SIGNIFICANCE

Our study provides the first preclinical evidence that TMZ attenuates CP-induced urotoxicity by enhancing anti-oxidant capacity and suppressing inflammation possibly via downregulating TLR4-mediated NFκB signaling while augmenting the cytotoxicity of CP.