Description:
<jats:title>Abstract</jats:title>
<jats:p>Progress has recently been made in identifying populations at risk for lung cancer using genetic, clinical and demographic information. The N-nitroso-tris-chloroethylurea (NTCU) mouse model, in which animals develop premalignant histopathology similar to that seen in humans, is used to examine the potential efficacy of chemoprevention agents to be utilized in at risk populations. We identified 25 µl of 40 mM NTCU /week as the optimal dosing regimen in SWR/J mice for chemoprevention studies. At this dose, topical treatments of NTCU induce predominantly low-grade dysplastic lesions by 15 weeks (w) and high-grade dysplastic (HGD) lesions by 25 w in the large airways. Additionally we found that NTCU stimulates a state of chronic inflammation associated with the development of dysplasias.</jats:p>
<jats:p>Epidemiologic studies indicate that there is an inverse relationship between vitamin D and the risk and prognosis of lung cancer. Vitamin D acts through the vitamin D receptor to promote cellular differentiation and inhibit proliferation and inflammation. The effect of vitamin D on cancer progression was tested in the NTCU model, using dietary vitamin D3 (0 or 2000 IU/kg) alone and in combination with intraperitoneal injections of the active metabolite of vitamin D, calcitriol (80 ug/kg). Female mice were randomized to 6 treatment groups (n=15 mice/group/time point (15 and 25 w)). Disease was evaluated by enumerating the percentage of HGD lesions, per the total area in serial H&E sections of the lung. The percentage of HGD lesions in the large airways was reduced in the vitamin D sufficient mice (SN) (8.72%, P&lt;0.05), SN + calcitriol (SN+C) (6.59%, P&lt;0.05) and the vitamin D deficient + calcitriol (DN+C) (12.3% P&lt;0.05) groups compared to the DN (22.67%) group after 15 w of NTCU. The percentage of HGD lesions in the SN groups remained significantly less than the DN (35.5%) and DN+C (21.3%) groups, with little increase in the SN (8.43% P&lt;0.05) and SN+C (11.81% not significant (NS)) groups after 25 w.</jats:p>
<jats:p>Furthermore, there was a significant increase in proliferation associated with increased HGD. Following 25 w of NTCU treatment there was a 2-fold increase in Ki-67 staining all groups compared all groups after 15 w of NTCU. However, the was 30% more Ki-67staining in the DN (P&lt;0.001) group and addition of calcitriol reduced proliferation by 12% and 6% in the DN+C (P&lt;0.01) and SN+C (NS) groups. Moreover, vitamin D deficiency was associated with an increased systemic and local inflammation marked by a 3-fold increase in circulating white blood cells (WBCs) (P&lt;0.05), a 20% increase in IL-6 levels (P&lt;0.05) and a 4 -fold increase in WBCs in bronchial lavages (P&lt; 0.05) in the DN group. In conclusion this study indicates that vitamin D deficiency promotes the development of dysplasia, increases proliferation and inflammation, which is likely promote the development of frank squamous cell carcinoma. Supported by NIH/NCCAM F31AT0006487 (Mazzilli) NIH/NCI CA067267 (Johnson) </jats:p>
<jats:p>Citation Format: Sarah A. Mazzilli, Mary E. Reid, Paul N. Bogner, Kristopher Attwood, Pamela A. Hershberger, Donald L. Trump, Candace S. Johnson. Vitamin D sufficiency slows the progression of dysplasic lesions in the NTCU mouse model of lung squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 238. doi:10.1158/1538-7445.AM2014-238</jats:p>