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

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

New paradigms to assess consequences of long-term low-dose curcumin exposure in lung cancer cells.

Curcumin has been investigated extensively for cancer prevention, but it has been proposed that long-term treatments may promote clonal evolution and gain of cellular resistance, potentially rendering cancer cells less sensitive to future therapeutic interventions. Here, we used long-term, low-dose treatments to determine the potential for adverse effects in non-small cell lung cancer (NSCLC) cells. IC50s for curcumin, cisplatin, and pemetrexed in A549, PC9, and PC9ER NSCLC cells were evaluated using growth curves. IC50s were subsequently re-assessed following long-term, low-dose curcumin treatment and a three-month treatment withdrawal period, with a concurrent assessment of oncology-related protein expression. Doublet cisplatin/pemetrexed-resistant cell lines were created and the IC50 for curcumin was determined. Organotypic NSCLC-fibroblast co-culture models were used to assess the effects of curcumin on invasive capacity. Following long-term treatment/treatment withdrawal, there was no significant change in IC50s for the chemotherapy drugs, with chemotherapy-resistant cell lines exhibiting similar sensitivity to curcumin as their non-resistant counterparts. Curcumin (0.25–0.5 µM) was able to inhibit the invasion of both native and chemo-resistant NSCLC cells in the organotypic co-culture model. In summary, long-term curcumin treatment in models of NSCLC neither resulted in the acquisition of pro-carcinogenic phenotypes nor caused resistance to chemotherapy agents

The role of stromal fibroblasts in lung carcinogenesis: a target for chemoprevention?

The tumour microenvironment plays an essential role in the development and spread of cancers. Tumour cells interact with the surrounding extracellular matrix (ECM), embedded within which, are a variety of non-cancer cells including cells of the vasculature, immune system and fibroblasts. The essential role of fibroblasts in the cultivation and maintenance of an environment in which tumour cells are able to maintain their aggressive phenotypic traits is becoming increasingly well documented. Cancer-associated fibroblasts are able to secrete a vast array of ECM-modulating factors, meaning that they have potential for a functional role in every step of the carcinogenic process. In particular, they are likely to have a role in early tumour-initiating inflammatory events, and so may provide a potential target for chemopreventive intervention. This review summarises the known interactions between lung tumour cells and surrounding reactive fibroblasts, highlighting the need to further investigate cancer-associated fibroblasts as therapeutic targets in lung cancer chemoprevention strategies