Violacein, an indole-derived purple-colored natural pigment produced by Janthinobacterium lividum, inhibits the growth of head and neck carcinoma cell lines both in vitro and in vivo

Abstract

Violacein (VIO; 3-[1,2-dihydro-5-(5-hydroxy-1H-indol-3-yl)-2-oxo-3H-pyrrol-3-ylidene]-1,3-dihydro-2H-indol-2-one), an indole-derived purple-colored pigment, produced by a limited number of Gram-negative bacteria species, including Chromobacterium violaceum and Janthinobacterium lividum, has been demonstrated to have anti-cancer activity, as it interferes with survival transduction signaling pathways in different cancer models. Head and neck carcinoma (HNC) represents the sixth most common and one of the most fatal cancers worldwide. We determined whether VIO was able to inhibit head and neck cancer cell growth both in vitro and in vivo. We provide evidence that VIO treatment of human and mouse head and neck cancer cell lines inhibits cell growth and induces autophagy and apoptosis. In fact, VIO treatment increased PARP-1 cleavage, the Bax/Bcl-2 ratio, the inhibition of ERK1 and ERK2 phosphorylation, and the expression of light chain 3-II (LC3-II). Moreover, VIO was able to induce p53 degradation, cytoplasmic nuclear factor kappa B (NF-κB) accumulation, and reactive oxygen species (ROS) production. VIO induced a significant increase in ROS production. VIO administration was safe in BALB/c mice and reduced the growth of transplanted salivary gland cancer cells (SALTO) in vivo and prolonged median survival. Taken together, our results indicate that the treatment of head and neck cancer cells with VIO can be useful in inhibiting in vivo and in vitro cancer cell growth. VIO may represent a suitable tool for the local treatment of HNC in combination with standard therapies.

Curcumin blocks autophagy and activates apoptosis of malignant mesothelioma cell lines and increases the survival of mice intraperitoneally transplanted with a malignant mesothelioma cell line

“…Briefly, 2.5×10 5 cells were seeded into 6-well plates and incubated at 37 °C to allow cells attachment before treatment. After two washings with PBS, cells were incubated with 10 μM 2′,7′-dichlorofluorescein diacetate (Sigma-Aldrich, Milan, Italy) in PBS at 37°C and 5% CO 2 in the dark for 30 min [76]. After two washings, cells were treated with CUR (6.25-50 μM) or DMSO in serum-free medium and incubated at 37°C and 5% CO 2 in the dark for different times (15 min-4 hours).…”

The Potential Protective Effects of Polyphenols in Asbestos-Mediated Inflammation and Carcinogenesis of Mesothelium

“…Thus, intratumoral delivery of cancer therapeutics could be a more efficient route of administration for several agents in easily accessible tumors, such as MM. An intratumoral route of administration is able to prevent the occurrence of systemic side effects and makes the therapeutic agents directly available at the tumor site, allowing for the highest concentration close to tumor cells [ 40 ].…”

(±)-Gossypol induces apoptosis and autophagy in head and neck carcinoma cell lines and inhibits the growth of transplanted salivary gland cancer cells in BALB/c mice

“…Tumor growth was monitored weekly until tumorbearing mice were sacrificed at the first signs of distress or when their tumors exceeded 20 mm in width (Masuelli et al 2016). Tumors were measured with a caliper in two dimensions, and the volumes were calculated by using the following formula: (width 2 Â length)/2 (Bei et al 1998).…”