[[-2] proPSA: A Novel Marker of Prostate Cancer].

Over the decades, prostate-specific antigen (PSA) has contributed to the early detection of and screening for prostate cancer (PCa). However, PSA is now in the spotlight due to issues of overdetection and subsequent overtreatment of PCa, causing a serious drawback in PSA-based screening. The challenge of a PSA assay for PCa detection is that the sensitivity is high, whereas the specificity is relatively low. With advancements in molecular biology and genomics, numbers of novel PCa markers has been discovered. One of the promising serum biomarkers is proPSA. proPSA is a pre-mature form of PSA. The molecules are fractions of free PSA, and [-2]proPSA contains 2 amino acids as N-terminus pro-peptides of PSA. Studies have shown the possibilities of using [-2] proPSA-related indices like the Prostate Health Index and %2PSA as tumor markers for diagnosis. [-2]proPSA-related indices have improved specificity compared to commonly used PSA and free PSA to detect PCa, while maintaining high-level sensitivity. Reports on clinical utilities of [-2]proPSA are rapidly increasing, and recent studies suggested the utility of [-2] proPSA-related indices for the enhancement of optimized treatment strategies and patient management. At present, several investigations which may reveal clinical utilities of [-2]proPSA are on-going in Japan. Attention: At the time of the submission of this article, [-2] proPSA had yet to be approved as an in vitro diagnostic test in Japan.

Next-generation prostate-specific antigen test: precursor form of prostate-specific antigen.

An urgent need exists to develop a more sophisticated screening system in order to improve diagnostic accuracy of clinically significant cancer and also to reduce the drawbacks of prostate-specific antigen (PSA) screening including overdetection and overtreatment. The most promising next-generation PSA test, which can improve the management of prostate cancer, may be proenzyme PSA (proPSA) or precursor PSA (pPSA). proPSA has pro-leader peptide sequences of seven or less amino acids and previous studies demonstrated that [-2]proPSA, which contains only a 2-amino-acid propeptide leader, could be more useful not only to distinguish between men with and without cancer, but also between tumors with aggressive features with performance exceeding other classical PSA-related indices including ratio of free PSA to total PSA (%f-PSA) and PSA density. Recently, it was demonstrated that baseline [-2]proPSA-related indices were independent factors to predict pathological reclassification at one year or several years after entering active surveillance. Furthermore, a retrospective study suggested that [-2]proPSA might be a useful predictive marker for future developing clinically manifested prostate cancer as well as aggressive tumors. ProPSA-related indices may have the potential for developing a more ideal risk classification for men at risk for prostate cancer, with a screening system maintaining the sensitivity of detecting clinically significant prostate cancer while saving cost, individualized treatment strategies, and follow-up procedures of active surveillance or active treatments. At a minimum, proPSA will be one of the most important new markers on the prostate cancer management in the near future.

Utility of a panel of sera for the alignment of test results in the worldwide multicenter study on reference values.

BACKGROUND: In a planned International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) worldwide study on reference intervals (RIs), a common panel of serum samples is to be measured by laboratories from different countries, and test results are to be compared through conversion using linear regression analysis. This report presents a validation study that was conducted in collaboration with four laboratories. METHODS: A panel composed of 80 sera was prepared from healthy individuals, and 45 commonly tested analytes (general chemistry, tumor markers, and hormones) were measured on two occasions 1 week apart in each laboratory. Reduced major-axis linear regression was used to convert reference limits (LL and UL). Precision was expressed as a ratio of the standard error of converted LL or UL to the standard deviation (SD) comprising RI (approx. 1/4 of the RI width corresponding to between-individual SD). The allowable and optimal levels of error for the SD ratio (SDR) were set as ≤0.250 and ≤0.125, respectively, in analogy to the common method of setting limits for analytical bias based on between-individual SD. RESULTS: The values for the calculated SDRs depended upon the distribution patterns of test results: skewness toward higher values makes SDRLL lower and SDRUL higher. However, the CV of the regression line slope, CV(b), is less affected by skewness. The average of SDRLL and SDRUL (aveSDR) correlates closely with CV(b) (r=0.995). The aveSDRs of ≤0.25 and ≤0.125 corresponds approximately to CV(b) values of ≤11% and ≤5.5%, respectively. For all results (i.e., n=80), conversion was allowable (optimal) in 98% (89%) of the analytes, as judged by CV(b). Resampling studies using random subsets of data with a data size (n) of 70 to 20 revealed that SDRs and CV(b) gradually increase with reduction of n, especially with n ≤30. CONCLUSIONS: CV(b) is a robust estimator for judging the convertibility of reference values among laboratories, even with a skewed distribution. Assuming 40 sera to be a practical size for the panel, reference values of 89% (80%) of analytes examined were made comparable by regression analysis with the allowable (optimal) level of precision.

Efficient translation destabilizes transcripts in chloroplasts of Chlamydomonas reinhardtii.

We previously reported that high level of reporter gene transcript does not confer high amount of reporter protein accumulation in Chlamydomonas reinhardtii chloroplast transformants. Here, to further clarify the correlation between the level of transcript and protein accumulation, we generated the beta-glucuronidase (GUS) reporter gene (uidA) constructs with different potential for translation efficiency of the GUS protein by incorporating different 5' and 3'-untranslated regions of chloroplast genes into each construct. The relationship between mRNA stability and translation efficiency of the GUS reporter gene in each construct were then studied in C. reinhardtii stable chloroplast transformants. We found that sequences of the two nucleotides immediately upstream of the initial codon were important for translation efficiency and that transformants showing high GUS activity accumulated lower level of uidA transcripts than the transformants with low GUS activity. Moreover, accumulation and half-lives of these chimeric-uidA transcripts were increased to the same level in the presence of translation inhibitor. The accumulation and/or half-lives of several endogenous chloroplast transcripts were also increased by such inhibitor. Collectively, our results indicate that efficient translation destabilizes transcripts in chloroplasts of C. reinhardtii, and that there is an apparent negative correlation between protein accumulation and mRNA stability.

Effect of coding regions on chloroplast gene expression in Chlamydomonas reinhardtii.

An exogenous gene, placed between the 5'-upstream regions of the Chlamydomonas reinhardtii chloroplast genes, rbcL or psbA, and the 3'-end of the rbcL gene, do not have the same expression pattern as endogenous genes in the C. reinhardtii chloroplast. Here, we chose four chloroplast genes, rbcL, psbA, psbD and atpA, and examine the effects of chloroplast gene coding regions on gene expression in C. reinhardtii. We constructed chimeric genes composed of the promoter, 5'- and 3'-untranslated regions, varying lengths of protein coding regions of the chloroplast genes, and the bacterial beta-glucuronidase (GUS) gene (uidA) as a reporter gene, and introduced into chloroplast genomes. The transformants, which contained the rbcL-uidA and psbA-uidA chimeric genes fused to the coding region of each gene, showed high expression of uidA mRNA as compared with the previously generated transformants, RG and PG, in which uidA was only fused to the promoter and 5'-UTR of each gene. The difference in the accumulation of uidA transcripts among the transformants was the result of different rates of transcription. This result indicates that the coding region is necessary for sufficient expression of rbcL and psbA. On the other hand, the psbD and atpA coding region portions did not affect chimeric gene expression.