NC381, a Novel Anticancer Agent, Arrests the Cell Cycle in G₀-G₁ and Inhibits Lung Tumor Cell Growth in Vitro and in Vivo

Abstract

Although clotrimazole (CLT), an antifungal drug, inhibits tumor cell proliferation and angiogenesis, its clinical application is hampered by significant hepatotoxicity due to the presence of an imidazole moiety. In our attempts to develop CLT analogs that are devoid of imidazole and are as efficacious as CLT, one pharmacophore designated NC381 was generated and shown to inhibit tumor cell growth via a mechanism similar to that of CLT. In vitro, treatment of NCI-H460 nonsmall cell lung cancer (NSCLC) cells with NC381 inhibited growth in a time-dependent manner. Flow cytometric analysis demonstrated that the decrease in cell growth was associated with inhibition of cell cycle progression at the G 1 -S phase transition, resulting in G 0 -G 1 arrest. There was a concomitant inhibition of cyclin D1 expression and subsequent reduction in the formation of the cyclin D1-CDK4 complex. Consistent with a decrease in the cyclin D1-CDK4 complex, NC381 treatment resulted in significant inhibition of pRb phosphorylation. There also were changes in the activity of cell cycle-related proteins, including p16Ink4 and p27 Kip1 . Together, these results are consistent with a model in which NC381 arrests cell cycle progression via inhibition of the pathway that promotes exit from the G 1 phase of the cell cycle. Furthermore, the clinical applicability of NC381 was evaluated in an in vivo murine xenograft model of human NSCLC (NCI-H460). NC381 treatment resulted in significant inhibition of tumor growth. Given the poor prognosis and the limited treatment options available, the present results underscore the potential of NC381 in the treatment of human NSCLC.

The In Vitro and In Vivo Antitumor Effects of Clotrimazole on Oral Squamous Cell Carcinoma

“…We found that clotrimazole blocked OSCC cycle progression at the G 0 /G 1 phase in vitro experiment. This result is consistent with previous studies, such as glioblastoma and lung cancer [10], [22]. Liu et al observed that clotrimazole arrested cell cycle at G 0 /G 1 phase correlating with the overexpression of p27 Kip and the decrease of cyclin D1 [12].…”

Clotrimazole induces a late G1 cell cycle arrest and sensitizes glioblastoma cells to radiation in vitro

“…This hypothesis is supported by a study treating non-small cell lung cancer cells with a clotrimazole analog (NC381), which showed that G 1 arrest was at the G 1 –S transition [15]. Our results showed that clotrimazole-treated U-87 MG cells resulted in a two-fold increase of p27 Kip protein expression corresponding to the increased arrest of cells in the G 1 phase and corresponding decrease in cells in the S phase and G 2 /M-phasc.…”

“…The limited studies with clotrimazole did not differentiate in which stage of the G 1 phase the arrest was located. However, a recent study with a clotrimazole analog, NC381, indicated that cell cycle arrest was in late G 1 at the G 1 –S phase transition [15]. Therefore, we hypothesized that clotrimazole would arrest tumor cells in the late G 1 cell cycle phase, thereby sensitizing tumor cells to radiation treatment (RT).…”

Analysis of the cytotoxic effects of ruthenium–ketoconazole and ruthenium–clotrimazole complexes on cancer cells

“…The increase in mitocondrially bound hexokinase, process associated to the high rate of glycolysis in cancer cells (Bratsos et al 2007a) is induced by insulin, Ca 2+ and Ca 2+ -mobilizing hormones, and it could be prevented by calmodulin antagonists (Penso and Beitner, 1998). In addition, CTZ induces Ca 2+ store-mediated inhibition of translation initiation (Cao et al 2004) and blocks calcium-activated potassium channel (IKCa1) on human T lymphocytes (Wulff et al 2000). …”