The isolation and identification of apolipoprotein C-I in hormone-refractory prostate cancer using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry

Androgens play a central role in prostate cancer pathogenesis, and hence most of the patients respond to androgen deprivation therapies. However, patients tend to relapse with aggressive prostate cancer, which has been termed as hormone refractory. To identify the proteins that mediate progression to the hormone-refractory state, we used protein-chip technology for mass profiling of patients＇ sera. This study included 16 patients with metastatic hormone-refractory prostate cancer who were initially treated with androgen deprivation therapy. Serum samples were collected from each patient at five time points： point A, pre-treatment; point B, at the nadir of the prostate- specific antigen （PSA） level; point C, PSA failure; point D, the early hormone-refractory phase; and point E, the late hormone-refractory phase. Using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, we performed protein mass profiling of the patients＇ sera and identified a 6 640-Da peak that increased with disease progression. Target proteins were partially purified, and by amino acid sequencing the peak was identified as a fragment of apolipoprotein C-I （ApoC-I）. Serum ApoC-I protein levels increased with disease progression. On immunohistochemical analysis, the ApoC-i protein was found localized to the cytoplasm of the hormone-refractory cancer cells. In this study, we showed an increase in serum ApoC-I protein levels in prostate cancer patients during their progression to the hormone-refractory state, which suggests that ApoC-I protein is related to progression of prostate cancer. However, as the exact role of ApoC-I in prostate cancer pathogenesis is unclear, further research is required.

Fractionation of gamma-glutamyltransferase in patients with nonalcoholic fatty liver disease and alcoholic liver disease

AIM To assess how serum gamma-glutamyltransferase(GGT) fractions vary in patients with alcoholic liver disease(ALD) and non-alcoholic fatty liver disease(NAFLD). METHODS Serum samples were obtained from 14 patients with biopsy-proven alcoholic liver diseases and 9 patients with biopsy proven non-alcoholic fatty liver disease. In addition to these biopsy-proven cases, 16 obese(body mass index > 25) patients without any history of alcohol consumption but with a fatty liver on ultrasound examination and with elevated GGT were included for an additional analysis. Serum GGT fractionation was conducted by high-performance gel filtration liquid chromatography and was separated into the four fractions, big-GGT, medium-GGT, small-GGT(s-GGT), and free-GGT(f-GGT).RESULTS The results were expressed as a ratio of each fraction including the total GGT(t-GGT). The s-GGT/t-GGT ratioswere lowest for the control group and highest for the ALD group. The differences between the control and NAFLD groups and also between the NAFLD and ALD groups were statistically significant. In contrast, the f-GGT/t-GGT ratios were highest in the control group and lowest in the ALD group, with the differences being statistically significant. As a result, the s-GGT/f-GGT ratios were markedly increased in the NAFLD group as compared with the control group. The increase of the s-GGT/t-GGT ratios, the decrease of the f-GGT/t-GGT ratios, and the increase of s-GGT/F-GGT ratios as compared with the control group subjects were also found in obese patients with clinically diagnosed fatty change of the liver.CONCLUSION Serum GGT fractionation by high-performance gel filtration liquid chromatography is potentially useful for the differential diagnosis of ALD and NAFLD.