Combination of carbonic anhydrase inhibitor, acetazolamide, and sulforaphane, reduces the viability and growth of bronchial carcinoid cell lines

Abstract

BackgroundBronchial carcinoids are pulmonary neuroendocrine cell-derived tumors comprising typical (TC) and atypical (AC) malignant phenotypes. The 5-year survival rate in metastatic carcinoid, despite multiple current therapies, is 14-25%. Hence, we are testing novel therapies that can affect the proliferation and survival of bronchial carcinoids.MethodsIn vitro studies were used for the dose–response (AlamarBlue) effects of acetazolamide (AZ) and sulforaphane (SFN) on clonogenicity, serotonin-induced growth effect and serotonin content (LC-MS) on H-727 (TC) and H-720 (AC) bronchial carcinoid cell lines and their derived NOD/SCID mice subcutaneous xenografts. Tumor ultra structure was studied by electron microscopy. Invasive fraction of the tumors was determined by matrigel invasion assay. Immunohistochemistry was conducted to study the effect of treatment(s) on proliferation (Ki67, phospho histone-H3) and neuroendocrine phenotype (chromogranin-A, tryptophan hydroxylase).ResultsBoth compounds significantly reduced cell viability and colony formation in a dose-dependent manner (0–80 μM, 48 hours and 7 days) in H-727 and H-720 cell lines. Treatment of H-727 and H-720 subcutaneous xenografts in NOD/SCID mice with the combination of AZ + SFN for two weeks demonstrated highly significant growth inhibition and reduction of 5-HT content and reduced the invasive capacity of H-727 tumor cells. In terms of the tumor ultra structure, a marked reduction in secretory vesicles correlated with the decrease in 5-HT content.ConclusionsThe combination of AZ and SFN was more effective than either single agent. Since the effective doses are well within clinical range and bioavailability, our results suggest a potential new therapeutic strategy for the treatment of bronchial carcinoids.

Targeting carbonic anhydrase IX improves the anti-cancer efficacy of mTOR inhibitors

“…For instance, renal cancer cell invasiveness and survival is diminished by acetazolamide in vitro [40, 41]. In addition, acetazolamide has shown anti-tumor properties in murine models [14, 42, 43]. Our data further demonstrate that acetazolamide-induced tumor growth inhibition is associated with reduced cancer cell proliferation in hypoxic zones (Figure 6A and 6B), which is in accordance with what we observe following selective knockdown of CAIX (Figure 7D).…”

Simultaneous Targeting of Bladder Tumor Growth, Survival, and Epithelial-to-Mesenchymal Transition with a Novel Therapeutic Combination of Acetazolamide (AZ) and Sulforaphane (SFN)

“…Significant inhibitory effects were documented both in vitro and in vivo at concentrations that are non-toxic to normal bladder. The concentrations are within the clinically achievable level for AZ, already used for various other treatments [13], and close to that achievable for SFN, which is intrinsically non-toxic in these dose ranges [58]. We therefore suggest that the AZ+ SFN combination has clinical value and should be considered for trial therapy in bladder cancers with the added advantage that SFN might be effective in the chemoprevention of bladder cancer and maintenance of normal tissue health.…”

“…However, when comparing the expression of caspase-3 and PARP after SFN alone with AZ+SFN in HTB-9 cells, the expression increased by 1.5-fold only, although this was still a significant difference. Based on previous studies [13], we suggest that a longer time period for treatment would be predicted to produce greater differences.…”

“…In another study, AZ treatment reduced tumor growth when delivered as a single agent, while combination with other chemotherapeutic agents such as aromatic sulfonamides significantly delayed tumour growth [12]. Recent studies from our laboratory have shown that AZ can also potentiate the antitumor efficacy of natural compounds such as sulforaphane, an isothiocyanate compound with significant anti-tumor properties in lung carcinoids [13].…”

Pulmonary neuroepithelial bodies are polymodal airway sensors: Evidence for CO2/H+sensing

“…Interestingly, this growth seems to be driven by 5-HT released from tumor cells. We have shown recently that inhibition of CAII in lung carcinoid cell line H727 cells maintained in vitro and in a xenograft model suppresses tumor cell proliferation and causes significant reduction in tumor mass, indicating a potential therapeutic target (22,37). This suggests that elucidating further components of the CO 2 and acid-sensing pathways may prompt the discovery of further potential therapeutic targets in the treatment of lung cancers.…”