Human rhomboid family‐1 gene
            RHBDF1
            participates in GPCR‐mediated transactivation of EGFR growth signals in head and neck squamous cancer cells

Tobacco smoking is a common risk factor for lung cancer and head and neck cancer. Molecular changes such as deregulation of miRNA expression have been linked to tobacco smoking in both types of cancer. Dysfunction of the Mismatch DNA repair (MMR) mechanism has also been associated with a poor prognosis of these cancers, while a cross-talk between specific miRNAs and MMR genes has been previously proposed. We hypothesized that exposure of lung and head and neck squamous cancer cells (NCI and FaDu, respectively) to tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is capable of altering the expression of MSH2 and MLH1, key MMR components, by promoting specific miRNA deregulation. We found that either a low (1 μM) or high (2 μM) dose of NNK induced significant upregulation of “oncomirs” miR-21 and miR-155 and downregulation of “tumor suppressor” miR-422a, as well as the reduction of MMR protein and mRNA expression, in NCI and FaDu, compared to controls. Inhibition of miR-21 restored the NNK-induced reduced MSH2 phenotype in both NCI and FaDu, indicating that miR-21 might contribute to MSH2 regulation. Finally, NNK exposure increased NCI and FaDu survival, promoting cancer cell progression. We provide novel findings that deregulated miR-21, miR-155, and miR-422a and MMR gene expression patterns may be valuable biomarkers for lung and head and neck squamous cell cancer progression in smokers.

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In Vitro Photosensitization of Human Head and Neck Squamous Cancer Cells by Dihematoporphyrin-Ether

Otolaryngology ◽

10.1177/019459988809900105 ◽

1988 ◽

Vol 99 (1) ◽

pp. 28-37 ◽

Cited By ~ 5

Author(s):

Sherman A. Sprik ◽

Michael J. Sullivan ◽

Thomas E. Carey

Keyword(s):

Malignant Melanoma ◽

Cell Viability ◽

Head And Neck ◽

Cancer Cells ◽

Cell Line ◽

Light Exposure ◽

Blue Dye ◽

Squamous Cancer ◽

Dose Dependent

In vitro experiments were performed to evaluate the direct cytotoxic and photosensitizing effects of dihematoporphyrin-ether (DHE) on the head and neck squamous cancer cell line, UM-SCC-38. Normal fibroblasts, normal cultured keratinocytes, and the UM-MEL-1 pigmented malignant melanoma cell line were used as controls. The parameters of duration of light exposure, drug concentration, and incubation periods were studied. Uptake of DHE by squamous cancer cells, as assessed microscopically by intensity of fluorescence, was rapid and reached a dose-dependent maximum intensity within 10 minutes. Cells were irradiated with polychromatic light with an energy of one milliwatt/cm2 at a distance of 1.5 ft. Cells growing in plastic dishes were incubated in the dark for 1 to 4 hours with DHE in concentrations that ranged from 1.25 to 50 μg/ml. The cell monolayers were washed and irradiated for periods of time ranging from 15 to 120 min. Dose-dependent loss of cell viability could be detected by trypan blue dye uptake as early as 1 hour after radiation and continued to increase until 4 hours after light exposure. No further loss of cell viability was observed over the next 10 hours. There was no phototoxicity in the absence of DHE. UM-SCC-38 cells were more sensitive to the photosensitizing effects of DHE than were either normal fibroblasts or malignant melanoma cells. Recovery from the photosensitizing effects of DHE was observed if the DHE-containing medium was removed and the cells were incubated in the dark for periods that ranged from 1 to 14 hours before light exposure. UM-SCC-38 cells recovered more rapidly than normal fibroblasts, normal keratinocytes, or UM-MEL-1 cells.

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