β-Carotene promotes the development of NNK-induced small airway-derived lung adenocarcinoma

Abstract

Aim-Beta-carotene has shown cancer preventive effects in preclinical studies while increasing lung cancer mortality in clinical trials. We have shown that β-carotene stimulates cAMP signaling in vitro. Here, we have tested the hypothesis that beta-carotene promotes the development of pulmonary adenocarcinoma (PAC) in vivo via cAMP signaling. Methods: PAC was induced in hamsters with the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) followed by β-carotene for 1.5 years. Incidence, multiplicity and size of lung tumors were recorded and phosphorylated CREB and ERK1/2 in tumour cells determined by Western blots. Cyclic AMP in blood cells was analysed by immunoassays, retinoids in serum and lungs by HPLC. Results: beta-carotene increased lung tumor multiplicity, lung tumour size, blood cell cAMP, serum and lung levels of retinoids and induced p-CREB and p-ERK1/2 in lung tumours. Conclusions:Our data suggest that beta-carotene promotes the development of PAC via increased cAMP signaling.

Repurposing established cyclic adenosine monophosphate reducing agents for the prevention and therapy of epidermal growth factor receptor inhibitor resistance in non-small cell lung cancer

“…In fact, this mechanism of action likely triggered the increase in lung adenocarcinoma incidence that lead to the discontinuation of a lung cancer prevention trial by β-carotene and retinoid supplementation (34). This interpretation is supported by observations that β-carotene stimulated the growth of lung adenocarcinoma cells in vitro via cAMP signaling (32) and promoted the development of NNK-induced lung adenocarcinomas in hamsters via this mechanism (33).…”

“…Vitamin A, β-carotene and retinoids initially believed to act through nuclear receptors increase cAMP via similar non-genomic signaling (32,33). In fact, this mechanism of action likely triggered the increase in lung adenocarcinoma incidence that lead to the discontinuation of a lung cancer prevention trial by β-carotene and retinoid supplementation (34).…”

Chronic exposure to estrogen and the tobacco carcinogen NNK cooperatively modulates nicotinic receptors in small airway epithelial cells

“…These functions have important implications for the genesis of small airway-derived adenocarcinoma, a type of lung cancer par- ticularly prevalent in women. We have previously shown that cAMP signaling stimulates the proliferation and migration of human small airway epithelial cells and adenocarcinoma cells [8][9][10] and has strong cancer promoting effects on this type of lung cancer induced by NNK in hamsters [28,32,33]. The antagonistic role of stimulatory noradrenaline and inhibitory GABA on cAMP suggests therefore that an increase in noradrenaline production accompanied by a deficiency in GABA may be a strong driving force for the development and progression of small airway-derived adenocarcinoma.…”

“…It has been shown that noradrenaline stimulates the proliferation and migration of numerous human cancers, including small airway-derived adenocarcinoma, via cAMP signaling downstream of ␤-ARs [20][21][22][23][24][25][26][27][28][29][30]. In addition, we have shown that treatment of HPL1D cells with NNK via the ␤1-AR and E2 via the ER␤ cooperatively increased intracellular cAMP [10].…”

“…Following lysis of the thawed tissues, protein was determined using the BCA Protein Assay (Pierce, Rockford, IL). Western blots were done by a standard protocol previously described [28], using 12% polyacrylamide gel for electrophoresis followed by transfer of the electrophoresed proteins onto nitrocellulose membranes at 100 mV for 1 h. Incubation with primary antibodies was overnight at 4 • C. Primary antibodies against the following signaling proteins were used: ␣4-and ␣7nAChR , GAD65 (Millipore, Billerica, MA, USA) and betaactin (Sigma). After being washed with TBST, the membranes were incubated with horseradish peroxidase-labeled secondary antibody (goat anti-mouse, or goat anti-rabbit, Cell Signaling) for 1 h. Immunoreactive bands were detected using a chemiluminescent reaction (ECL, Amersham Biosciences, Piscataway, NJ) via autoradiography on Kodak Bio-Max XAR film.…”