Preclinical Evaluation Of Curcumin And Its Meriva Formulation For Non-Small Cell Lung Cancer Chemoprevention

Abstract

The naturally derived polyphenol curcumin has been investigated for prevention and treatment of many cancers over the past few decades. Accumulating evidence demonstrates that curcumin can target many tumorigenic pathways in cancer cells, rendering it a compound of interest for systematic investigation into prevention and treatment of an array of diseases, including non-small cell lung cancer (NSCLC). IC50 values for curcumin and first-line chemotherapeutic agents cisplatin and pemetrexed, were determined for A549, PC9 and PC9ER NSCLC cell lines. IC50s were then reassessed following long-term (>3 months), low-dose treatment with pharmacologically achievable curcumin doses to determine whether resistant subclones may develop. No significant changes in IC50 values were observed in any of the cell lines. Minor changes to expression of oncology-related proteins were concurrently observed, which reverted back to pre-treatment levels of expression following curcumin withdrawal. Cisplatin/pemetrexed double resistant cell lines were developed, and showed greater sensitivity to curcumin compared to their native cell line counterparts. Development of organotypic fibroblast co-cultures allowed assessment of cell invasion in a 3D model, creating better replication of cell-cell interactions within a more physiologically relevant environment. Co-culture models revealed that curcumin was able to inhibit invasion of NSCLC cells into a fibroblast-containing scaffold, with efficacy greatest at 0.25 – 0.5 μM curcumin, representing a non-linear dose response pattern. Furthermore, curcumin showed higher efficacy in supressing invasion of PC9 and PC9ER cisplatin/pemetrexed double resistant cell lines, reducing the area of invasion by up to 36% compared to that observed for their native non-resistant counterparts. In vivo, the bioavailable formulation of curcumin (Meriva) did not elicit significant effects on tumour multiplicity in the KRASG12D transgenic mouse model. However, decreased weight loss was observed in animals consuming Meriva, in addition to observing a decreased proliferative index in tumours compared to those animals fed control diet. Pharmacokinetic analysis demonstrated that dietary supplementation of 0.226% Meriva was sufficient to furnish lung tissue with detectable amounts of curcumin and its metabolites, proving that curcumin could be successfully delivered to the target tissues via an oral dosing regimen. This thesis has evaluated whether there may be potential for benefit or adverse effects of curcumin in lung cancer prevention regimens. Evidence presented suggests that long term curcumin treatment neither results in acquired resistance, nor causes resistance to standard-of-care chemotherapy agents. Furthermore, chemotherapy resistant subclones appear more sensitive to curcumin than their native counterparts, and in particular, curcumin is more potent in cells bearing EGFR mutational status compared to KRAS. Curcumin (delivered as the Meriva formulation) successfully reaches its target tissue (lung), and alleviates cancer associated weight loss in the KRAS mouse model