Search

A 4-mo history of both epigastralgia and back pain was presented in a 39-year-old male. Computed tomography showed right lung nodule and abdominal mass attached to the gastric wall, measuring approximately 30 mm and 70 mm in diameter. Since biopsy samples from the lung and abdomen revealed poorly differentiated adenocarcinoma and malignant tumor, clinicians first interpreted the abdominal mass as metastatic carcinoma, and a right lower lobectomy with following resection of the mass was performed. Gross examination of both lesions displayed gray-whitish to yellow-whitish cut surfaces with hemorrhagic and necrotic foci, and the mass attached to the serosa of the lesser curvature on the gastric body. On microscopic examination, the lung tumor was composed of a proliferation of highly atypical epithelial cells having abundant eosinophilic cytoplasm, predominantly arranged in an acinar or solid growth pattern with vessel permeation, while the abdominal tumor consisted of sheets or nests with markedly atypical epithelioid cells having pleomorphic nuclei and abundant eosinophilic to clear cytoplasm focally in a radial perivascular or infiltrative growth pattern. Immunohistochemically, the latter cells were positive for HMB45 or α-smooth muscle actin, but the former ones not. Therefore, we finally made a diagnosis of malignant perivascular epithelioid cell tumor (PEComa) arising in the gastric serosa, combined with primary lung adenocarcinoma. Furthermore, small papillary carcinoma of the thyroid gland was identified. The current case describes the coincidence of malignant PEComa with other carcinomas, posing a challenge in distinction from metastatic tumor disease.

Flavin adenine dinucleotide (FAD) is an essential coenzyme for glutathione reductase (GR) which catalyzes the reduction of oxidized glutathione to regenerate the reduced form involved in protection against oxidative stress. Riboflavin kinase (RFK) also known as flavokinase is involved in the first step of bioactivation of riboflavin (RF) to form flavin mononucleotide (FMN) which can be subsequently converted to FAD in an ATP-dependent reaction catalyzed by FAD synthetase (FADS). We investigated the involvement of RFK in cisplatin resistance using human prostate cancer PC3 cells. RFK overexpression renders cells resistant not only to cisplatin but also to hydrogen peroxide (H2O2) and diamide. Furthermore, knockdown of RFK expression induced apoptosis. We demonstrated that overexpression of RFK increased the levels of FAD, FMN and total glutathione and the expression of GR and glutathione S-transferase-π (GSTπ). RFK expression is up-regulated in cisplatin-resistant P/CDP6 cells in addition to FAD, total glutathione level, GR and GSTπ. Knockdown of RFK expression also sensitized both PC3 and P/CDP6 cells to cisplatin. Moreover, cellular levels of RFK expression correlate well with Gleason score, known as a good indicator of patient prognosis. The present study suggests that RFK expression is involved not only in cellular protection from oxidative stress but also in malignant progression of prostate cancer.