HER2 mRNA transcript quantitation in breast cancer

Purpose. The human epidermal growth factor receptor 2 (HER2) status in breast cancer is important for prognostic prediction and the determination of optimal treatment. Current methods rely on protein expression, as determined by immunohistochemistry (IHC), as well as gene amplification as determined by in situ hybridisation (ISH). We explored whether quantitative droplet digital PCR (ddPCR) can be used for the detection and absolute quantitation of HER2 mRNA. Methods. Digital droplet PCR (ddPCR) was performed for HER2 mRNA on 178 formalin-fixed paraffin-embedded (FFPE) breast cancer specimens. HER2 positive, equivocal and negative cases as defined by standard criteria were included and both core biopsies and tissue sections were assessed. Results. HER2 positive cases contained significantly higher levels of HER2 mRNA (169-1,000,000 copies/µl) by ddPCR compared with equivocal (112-139 copies/µl, p = 0.025) and negative cases (6.2-644 copies/µl. p < 0.001). A continuum of transcript quantity was observed but a cutoff of 490 copies/µl distinguished between HER2 positive and negative cases. Results were consistent between core biopsy and tissue sections. Conclusions. ddPCR can be used to quantify HER2 mRNA transcripts in FFPE breast cancer specimens. Our results highlight the potential of ddPCR on FFPE tissue to be used to accurately quantify HER2 transcripts. Validation in large cohorts will be required to determine a clinically applicable cutoff (AU)

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HER2 mRNA transcript quantitation in breast cancer.

PURPOSE: The human epidermal growth factor receptor 2 (HER2) status in breast cancer is important for prognostic prediction and the determination of optimal treatment. Current methods rely on protein expression, as determined by immunohistochemistry (IHC), as well as gene amplification as determined by in situ hybridisation (ISH). We explored whether quantitative droplet digital PCR (ddPCR) can be used for the detection and absolute quantitation of HER2 mRNA. METHODS: Digital droplet PCR (ddPCR) was performed for HER2 mRNA on 178 formalin-fixed paraffin-embedded (FFPE) breast cancer specimens. HER2 positive, equivocal and negative cases as defined by standard criteria were included and both core biopsies and tissue sections were assessed. RESULTS: HER2 positive cases contained significantly higher levels of HER2 mRNA (169-1,000,000 copies/µl) by ddPCR compared with equivocal (112-139 copies/µl, p = 0.025) and negative cases (6.2-644 copies/µl. p < 0.001). A continuum of transcript quantity was observed but a cutoff of 490 copies/µl distinguished between HER2 positive and negative cases. Results were consistent between core biopsy and tissue sections. CONCLUSIONS: ddPCR can be used to quantify HER2 mRNA transcripts in FFPE breast cancer specimens. Our results highlight the potential of ddPCR on FFPE tissue to be used to accurately quantify HER2 transcripts. Validation in large cohorts will be required to determine a clinically applicable cutoff.

The identification of a common pathogen-specific HLA class I A*0201-restricted cytotoxic T cell epitope encoded within the heat shock protein 65.

Bacterial antigens recognized by CD8(+) T cells in the context of MHC class I are thought to play a crucial role in protection against pathogenic intracellular bacteria. Here, we demonstrate the induction of HLA-A*0201-restricted CD8(+) T cell responses against six new high-affinity HLA-A*0201-binding CTL epitopes, encoded within an immunodominant and highly conserved antigen of Mycobacteria, the heat shock protein 65 (hsp65). One of these epitopes, Mhsp65(9(369)), is identical in a large number of pathogenic bacteria, and is recognized in a CD8-independent fashion. Mhsp65(9(369)) could be presented by either mycobacterial hsp65-pulsed target cells or BCG-infected macrophages. Interestingly, T cells specific for this epitope did not recognize the corresponding human hsp65 homologue, probably due to structural differences as revealed by modeling studies. Furthermore, in vitro proteasome digestion analyses show that, whereas the mycobacterial hsp65 epitope is efficiently generated, the human hsp65 homologue is not, thus avoiding the induction of autoreactivity. Collectively, these findings describe high-affinity HLA class I-binding epitopes that are naturally processed and are recognized efficiently by MHC class I-restricted CD8(+) T cells, providing a rational basis for the development of subunit vaccine strategies against tuberculosis and other intracellular infectious diseases.

Optimization of polymerase chain reaction for detection of HIV type 2 DNA.

The aim of this study was to increase the sensitivity of an earlier version of an HIV-2 nested PCR assay based on primers in the gag, pol, LTR, and env regions. The assay was first optimized with regard to concentrations of dNTP, MgCl2, and primers, using a method that allowed optimization of all three parameters in only two test runs. We then designed and optimized new primer sets in the LTR, gag, and gag/pol regions that were based on more isolates than were the former (old) primer sets. Samples from 57 HIV-2 antibody-positive individuals were tested with the four old primer sets as well as with the three new primer sets. Five primer sets from this run (new gag, new gag/pol, old LTR, old env, and new LTR) were then tested with 35 more samples, giving a total number of 92 tested samples from HIV-2-infected individuals. At initial testing of the 92 samples a combination of primer sets from two different regions yielded a sensitivity ranging from 93.5 to 98.9%. After repeated testing the sensitivity ranged from 96.7 to 100% for the different primer combinations. The specificity was 100% for all primer sets except old LTR, which had a specificity of 97%. In conclusion, it is possible to create a more sensitive PCR assay by optimizing the different PCR parameters as well as by including primer sets based on more isolates.

Potent tetracyclic guanine inhibitors of PDE1 and PDE5 cyclic guanosine monophosphate phosphodiesterases with oral antihypertensive activity.

Tetracyclic guanines have been shown to be potent and selective inhibitors of the cGMP-hydrolyzing enzymes PDE1 and PDE5. In general, these compounds are inactive or only weakly active as inhibitors of PDE3, which is a major isozyme involved in cAMP hydrolysis. Structure-activity relationships are developed at N-1, C-2, N-3, and N-5 on the core nucleus. Compound 31, with an IC50 of 70 pM, is the most potent inhibitor of PDE1, while 50, with an IC50 of 4 nM, is the most potent inhibitor of PDE5. Compounds 20, 22, 30, and 50 are potent dual inhibitors with IC50 values below 30 nM for both PDE1 and PDE5. Compounds 12, 20, and 28 reduced blood pressure by more than 45 mmHg when administered orally at 10 mg/kg to the spontaneously hypertensive rat (SHR).