Reverse Transcriptase-polymerase Chain Reaction Signal Research Articles

Detection of circulating tumor cells in patients with renal cell carcinoma by reverse transcriptase polymerase chain reaction for G250/MNCA-9: Results of a prospective trial

Objectives Radical nephrectomy displays the standard procedure for patients with localized renal cell carcinoma. The transperitoneal approach is often favored compared to the retroperitoneal approach because of the early ligation of the renal vessels, thereby tumor cell shedding by manipulation of the tumor is thought to be avoided. The aim of our study was to investigate the influence of the surgical technique on intraoperative tumor cell shedding. Furthermore, we evaluated the clinical course of the patients being operated on with either method in terms of complications, postoperative recovery, and hospital stay. Methods A total of 55 consecutive patients with renal tumors suspicious for malignancies were evaluated for this study. Peripheral blood samples were obtained from 44 patients at admission, intraoperatively (before and after kidney removal), and before discharge. Ribonucleic acid was extracted, converted to complementary deoxyribonucleic acid, and reverse transcriptase polymerase chain reaction (RT-PCR) with primers specific for G250/MNCA-9 was performed. Data regarding the clinical course of the patients were analyzed retrospectively by reviewing patient files. Results The clinical course for patients undergoing retroperitoneal nephrectomy was statistically different compared to the transperitoneal approach group regarding operating time and duration of drains, favoring the retroperitoneal approach group. Evaluation of MNCA-9 RT-PCR revealed no difference according to operative technique, tumor-nodes-metastasis, or clinical tumor stage. Despite this result, we found positive RT-PCR signals for MNCA-9 in patients with transitional cell cancer of the renal pelvis and benign renal lesions. Conclusions There is no clinical relevant difference between the transperitoneal and retroperitoneal approaches for radical nephrectomy. Furthermore, the retroperitoneal approach does not bear the risk of intraoperative tumor cell shedding by the handling of the tumor.

A case of coagulation factor V deficiency caused by compound heterozygous mutations in the factor V gene

We investigated the molecular basis of a severe factor V (FV) deficiency in a Japanese female, and identified two distinct mutations in the FV gene, a novel cytosine insertion (1943insC) and a previously reported point mutation (A5279G). We expected the patient to be a compound heterozygote for those mutations, as a 1943insC, but not an A5279G, was found in the mother and a sibling. The 1943insC will cause a frame-shift after 590Gln, resulting in amino acid substitutions with two abnormal residues followed by a stop codon in the FV A2 domain (FS592X). The A5279G will cause an amino acid alteration in the FV A3 domain (Y1702C), which has been observed in several ethnic groups. We found that both mutant mRNAs were detected by reverse transcriptase polymerase chain reaction (RT-PCR) in the patient's platelets, whereas no FV antigen and activity were detected in plasma. On the one hand, the RT-PCR signal from the FS592X-FV mutant mRNA was markedly reduced, suggesting that the RNA surveillance system would eliminate most of the abnormal FS592X-FV transcripts with a premature termination. On the other hand, expression analyses revealed that only small amounts of Y1702C-FV with a low specific activity were secreted, and that the FS592X-FV was not detected in cultured media. These data indicated that both mutant FV molecules would be impaired, at least in part, during the post-transcriptional process of protein synthesis and/or in secretion. Taken together, it seems to suggest that each gene mutation could be separately responsible for severe FV deficiency, while this phenotype is due to the in-trans combination of the two defects.

Identification and distribution of mouse carboxypeptidase A-6

Carboxypeptidase A-6 (CPA6) was recently discovered in the human genome. To gain information regarding the potential function of this novel protein, the mouse homolog of CPA6 was identified using a combination of bioinformatics and reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, homologs in rat, chicken, and frog were identified using a bioinformatics approach. The distribution of CPA6 mRNA in mouse tissues was examined using RT-PCR and in situ hybridization. A strong RT-PCR signal is detectable in olfactory bulb, and much lower levels are present in other regions such as the cerebral cortex, hippocampus, hypothalamus, striatum, and medulla. In peripheral tissues, a moderate RT-PCR signal is present in epididymis, and low levels are detectable in colon and spleen. The high level of CPA6 in adult mouse brain olfactory bulb was confirmed by in situ hybridization. Lower levels of CPA6 mRNA were found to be present in the cingulate cortex, lateral septum, pontine nucleus, and inferior olivary nucleus of the hindbrain. Within the olfactory bulb, CPA6 mRNA is enriched in the mitral and granular layer. A lower level of CPA6 mRNA is present in the internal and external plexiform layers, and no signal is detectable in the olfactory nerve layer. The distribution was also examined in whole embryos at embryonic day 14.5 and CPA6 mRNA was found to be enriched in eye, ear, osteoblasts, stomach, skin, dorsal root ganglia, and throughout the CNS. The presence of CPA6 mRNA in the rectus muscle layer of the eye at embryonic day 14.5 is consistent with the observation that the CPA6 gene is disrupted in a patient with Duane syndrome, a congenital eye defect. Taken together, the distribution of CPA6 suggests a specific role in a limited number of tissues, and it is possible that this role involves an aspect of cell migration.

Relationship of messenger RNA reverse transcriptase-polymerase chain reaction signal to Campylobacter spp. viability.

SUMMARY. Discriminating viable from dead cells is of importance in the development of bacterial detection methods. A positive reverse transcriptase-polymerase chain reaction (RT-PCR) amplification signal was tested as a potential predictor of chick colonization. Some researchers have suggested that the presence of messenger RNA (mRNA) may not correlate with cell viability. Chicken colonization by cells that have positive mRNA signal but that are noncultivable would provide a correlation in cell viability and persistence of mRNA. The role of a viable but noncultivable (VBNC) form of Campylobacter spp. for colonization of poultry could be verified by such an mRNA signal. The levels of four strains of Campylobacter spp., previously isolated from poultry feces, declined progressively over time, and loss of cultivability occurred after 6 to 7 wk incubation in phosphate-buffered saline (PBS) at 4 C. Cold-stored, noncultivable and heat-inactivated (60 C for 10 min) Campylobacter spp. produced inconsistent amplified products from RT-PCR assay, depending on the target transcripts and strains used, although all fresh cultures showed mRNA signals. For the most part, signals of mRNA species from VBNC and heat-killed Campylobacter spp. AH-1, AH-2, and CH-3 persisted. RT-PCR amplification of transcripts originating from the tkt and cmp genes and a 256-base pair amplicon (from a previously described putative haem-copper oxidase) provided consistent signals, whereas transcripts from the flaA gene did not. Presumed VBNC and heat-inactivated Campylobacter spp., which produced positive mRNA signal but was not cultivable by conventional culture-based methods, did not establish colonization in the intestine of chicks 7 days after challenge. These results lead us to question the correlation between mRNA durability with cell viability as well as the significance of the VBNC cells in environmental transmission of Campylobacter spp.

Hepatitis C virus in human B lymphocytes transformed by Epstein-Barr virus in vitro by in situ reverse transcriptase-polymerase chain reaction.

To study persistence and replication of hepatitis C virus (HCV) in patients' peripheral blood mononuclear cells (PBMC) cultured in vitro. Epstein Barr virus (EBV) was used to transform the hepatitis C virus from a HCV positive patient to permanent lymphoblastoid cell lines (LCL). Positive and negative HCV RNA strands of the cultured cells and growth media were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) each month. Core and NS5 proteins of HCV were further tested using immunohistochemical SP method and in situ RT-PCR. HCV RNA positive strands were consistently detected the cultured cells for one year. The negative-strand RNA in LCL cells and the positive-strand RNA in supernatants were observed intermittently. Immunohistochemical results medicated expression of HCV NS3 and C proteins in LCL cytoplasm mostly. The positive signal of PCR product was dark blue and mainly localized to the LCL cytoplasm. The RT-PCR signal was eliminated by overnight RNase digestion but not DNase digestion. HCV may exist and remain functional in a cultured cell line for a long period.

CD44 variant overexpression in gallbladder carcinoma associated with tumor dedifferentiation

Recent studies have suggested a correlation between increased or decreased expression of CD44 variant molecules and tumor metastasis. CD44 expression in gallbladder carcinoma was examined and compared with tumor differentiation. Eighty-three samples of gallbladder carcinoma, 17 gallbladder adenoma samples, and 66 normal control mucosa samples were stained immunohistochemically for CD44 standard form (CD44s), variant 3 (CD44v3), and variant 6 (CD44v6). RNA extracted from nine patients with carcinoma also was investigated with reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and Southern blot hybridization (SBH) for the CD44 gene. Normal gallbladder mucosa showed strong, membranous staining for CD44s but not for CD44v3 or CD44v6. In gallbladder tumors, CD44s was stained as strongly as it was in normal mucosa, but immunoreactivity for CD44v3 and CD44v6 also was significant. In well differentiated, advanced adenocarcinomas (n = 38), CD44s immunoreactivity was significantly lower in the invasive component than in the intramucosal component of the tumors (P = 0.0048). Immunoreactivity for CD44v3 and CD44v6 in moderately and poorly differentiated areas was significantly higher than in well differentiated areas (P < 0.0001 and P = 0.0378, respectively). RT-PCR and SBH signals for CD44v3 and CD44v6, including exons 7 and 10, were strong in carcinoma samples but weak in normal samples, in line with the results of immunohistochemistry. The prognosis of patients with gallbladder carcinoma was not associated significantly with altered expression of CD44s, CD44v3, or CD44v6. The current study demonstrated that CD44 variant overexpression in patients with gallbladder carcinoma was linked closely with histologic dedifferentiation rather than clinicopathologic factors, including prognosis.

Estimating viability of Cryptosporidium parvum oocysts using reverse transcriptase-polymerase chain reaction (RT-PCR) directed at mRNA encoding amyloglucosidase

The purpose of the present study was to determine if reverse transcriptase-polymerase chain reaction (RT-PCR) directed at mRNA encoding the enzyme amyloglucosidase (CPAG) could serve as a indicator for C. parvum oocyst viability. Oocysts were stored for 1–11 months in the refrigerator and at monthly intervals extracted for total RNA for RT-PCR analysis. An aliquot of these C. parvum oocysts was inoculated into neonatal mice which were necropsied 4 days later for ileal tissue that was analyzed by semi-quantitative PCR to determine the level of parasite replication. The CPAG RT-PCR assay detected RNA from as few as 10 3 C. parvum oocysts. An effect of storage time on both RT-PCR signal and mouse infectivity was observed. RNA from oocysts stored for 1–7 months, unlike oocysts stored for 9 or 11 months, contained CPAG mRNA that was detectable by RT-PCR. A gradual decrease in the RT-PCR signal intensity was observed between 5 and 7 months storage. The intensity of RT-PCR product from oocysts and the signal from semi-quantitative PCR of ileal tissue DNA from mice infected with these same aged oocysts were comparable. The RT-PCR assay of CPAG mRNA in cultured cells infected with viable C. parvum oocysts first detected expression at 12 h with highest expression levels observed at 48 h post-infection. These results indicate that CPAG RT-PCR may be useful for differentiating viable from non-viable C. parvum oocysts and for studying the expression of the gene for amyloglucosidase in vitro.

Correlative Immunohistochemical and Reverse Transcriptase Polymerase Chain Reaction Analysis of Somatostatin Receptor Type 2 in Neuroendocrine Tumors of the Lung

Somatostatin receptors type 2 (sst2) have been frequently detected in neuroendocrine tumors and bind somatostatin analogues, such as octreotide, with high affinity. Receptor autoradiography, specific mRNA detection and, more recently, antisst2 polyclonal antibodies are currently employed to reveal sst2. The aim of the present study was to investigate by three different techniques the presence of sst2 in a series of 26 neuroendocrine tumors of the lung in which fresh frozen tissue and paraffin sections were available. It was possible, therefore, to compare, in individual cases, RNA analysis studied by reverse transcriptase polymerase chain reaction (RT-PCR), in situ hybridization (ISH), and immunohistochemistry. A series of 20 nonneuroendocrine lung carcinoma samples served as controls. RT-PCR was positive for sst2 in 22 of 26 samples, including 15 of 15 typical carcinoids, 5 of 6 atypical carcinoids, and 2 of 5 small-cell carcinomas. The sst2 mRNA signal obtained by RT-PCR was strong in the majority (87%) of typical carcinoids and of variable intensity in atypical carcinoids and small-cell carcinomas. A weakly positive signal was observed in 5 of 20 control samples. In immunohistochemistry, two different antibodies (anti-sst2) were employed, including a monoclonal antibody, generated in the Department of Pathology, University of Turin. In the majority of samples a good correlation between sst2 mRNA (as detected by RT-PCR) and sst2 protein expression (as detected by immunohistochemistry) was observed. However, one atypical carcinoid and one small-cell carcinoma had focal immunostaining but no RT-PCR signal. ISH performed in selected samples paralleled the results obtained with the other techniques. A low sst2 expression was associated with high grade neuroendocrine tumors and with aggressive behavior. It is concluded that 1) neuroendocrine tumors of the lung express sst2, and there is a correlation between the mRNA amount and the degree of differentiation; 2) immunohistochemistry and ISH are reliable tools to demonstrate sst2 in these tumors; and 3) sst2 identification in tissue sections may provide information on the diagnostic or therapeutic usefulness of somatostatin analogues in individual patients with neuroendocrine tumors.

RT-PCR amplification of CK19 mRNA in the blood of breast cancer patients: correlation with established prognostic parameters.

We optimized the assay for detection of cytokeratin 19 (CK19) mRNA by the reverse transcriptase-polymerase chain reaction (RT-PCR) in blood as an index of circulating tumor cells in breast cancer patients. The limit of detection of < 1 MCF7 tumor cells per 10(6) peripheral blood leukocytes (PBL) was achieved in mixing experiments. We did not detect CK19 mRNA in control bloods (0/30) or in the blood of patients with benign breast disease (0/15). In blood samples from 109 patients with invasive breast cancer, CK19 mRNA was detected in 7/23 patients with node-negative disease, in 21/58 with node-positive disease, and in 20/28 with distant metastases. There was a significant association (P < 0.01) of CK19 positivity with distant metastatic versus both node-negative and node-positive disease, but not with any other histopathological parameter examined. In a small number of patients with distant metastases, increased intensity of the CK19 RT-PCR signal was associated with a reduced survival.

Hepatitis C and human immunodeficiency virus RNA degradation by methylene blue/light treatment of human plasma.

Treatment of human plasma with methylene blue in combination with visible light (MB/light) inactivates several bloodborne viruses such as retro viruses and herpes viruses. The viral nucleic acid is thought to be a critical target for the inactivation procedure. We investigated the effects of photodynamic treatment on the RNA of hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) using Amplicor reverse transcriptase polymerase chain reaction (RT-PCR), which detects and quantifies a small fragment of the viral RNA. The detectable HCV RNA load (5-nontranslated region) in infected human plasma declined by 94-97 % within 10 min of illumination in small-scale experiments (1-2 ml vol.). Since the same effect was observed in both anti-HCV positive and negative ("window") samples, it can be concluded that HCV antibodies do not influence virus inactivation by photodynamic treatment. The effect of treatment on RT-PCR signals of HIV-1, which is known to be inactivated rapidly by MB/light treatment, was examined. Plasma was infected with HIV-1 and subjected to RT-PCR, which detected a part of the gag gene. The extent and kinetics of PCR signal reduction induced by MB/light treatment were similar to those observed for HCV. Experiments at production scale where single plasma units (300 ml) were infected with HCV showed reduction rates of PCR signals consistent with those measured in the small-scale experiments. The data support the view that MB/light treatment affects the viral nucleic acids and suggest that HCV is susceptible to the procedure.

Surface antigen expression on CD34+ cord blood cells: Comparative analysis by flow cytometry and limiting dilution (LD) RT-PCR of chymopapain-treated or untreated cells

Expression of antigens coexpressed on cord blood (CB) CD34+ cells was evaluated by flow cytometry analysis and reverse transcriptase polymerase chain reaction (RT-PCR). Antigen expression was also comparatively analyzed by flow cytometry and limiting dilution (LD) RT-PCR to investigate effects of chymopapain on epitopes of several cell surface markers: LD RT-PCR allows detection of the expression of antigens degraded by chymopapain which are not identified by flow cytometry. Monoclonal antibodies (MoAbs) that recognize chymopapain resistant epitopes on several coexpressed cell surface markers were identified: these included MoAbs directed against CD11a, CD13, CD18, CD38, CD45RO, CD51, HLA-DR, Thy-1, c-kit, flt-3 (STK-1), and mdr-1. Interestingly, chymopapain treatment caused enhanced staining with MoAbs against HLA-DR, Thy-1, flt-3, mdr-1, and CD51. The frequency (LD RT-PCR) of CD18, CD38, Thy-1, and c-kit RT-PCR signals on pure sorted CD34+ CD18-, CD34+ CD38-, CD34+ Thy-1-, and CD34+ c-kit- cells, respectively, was similar in corresponding subsets treated or not with chymopapain. In contrast, the frequency of CD33 RT-PCR signals on sorted CD34+ CD33- cells was higher in chymopapain-treated samples than in untreated samples and thus confirmed at the transcriptional level that the epitope recognized by anti-CD33 is chymopapain sensitive. Our findings extend data on the phenotypic profile of CB CD34+ cells and show that several key cell surface markers of hematopoietic progenitor cells are chymopapain resistant. In addition, the results of the present study demonstrate that the RT-PCR can be applied to the analysis of multiple RNA species in small numbers of hematopoietic progenitor cells and show that LD RT-PCR allows the identification and frequency determination of rare cells which are undetectable by flow cytometry.

Detection of tumour cells in peripheral blood and bone marrow from ewing tumour patients by rt‐pcr

The Ewing family of tumours (ET) is characterised at the cytogenetic level by unique chromosome 22 rearrangements. The breakpoints have been cloned and were shown to fuse the EWS gene on chromosome 22 to one of two closely related ETS proto-oncogenes, FLI-I or ERG, which reside on chromosomes II and 21, respectively. The rearrangement results in the expression of chimaeric transcripts, which can be identified by means of reverse transcriptase-polymerase chain reaction (RT-PCR). We applied this method for the monitoring of ET cells circulating in the peripheral blood or infiltrating the bone marrow. The presence of tumour cells could be detected with a sensitivity of I in I x 10(6) nucleated cells. When samples were kept at 4 degrees C, tumour cells could still be identified after 48 hr of storage. Positive RT-PCR signals originated from intact ET cells rather than from free RNA released by ruptured tumour cells. We analysed peripheral blood, bone marrow samples and peripheral blood stem cell collections from 16 ET patients. At diagnosis, bone marrow specimens collected from 6 patients and I peripheral blood specimen tested positive for EWS chimaeric RNA. During therapy tumour cells were detected in bone marrow aspirations obtained from 2 patients. Our results show that ET cells infiltrating the bone marrow or circulating in peripheral blood can be identified by RT-PCR. The clinical implications for the presence of ET cells in samples detected by RT-PCR at diagnosis and during therapy requires further evaluation.

In patients with BCR-ABL-positive ALL in CR peripheral blood contains less residual disease than bone marrow: implications for autologous BMT.

Residual leukemic cells are detectable at frequencies as low as 1 in 10(6) normal cells in patients with Philadelphia chromosome/BCR-ABL-positive leukemias in complete remission (CR) using reverse-transcriptase polymerase chain reaction (RT-PCR) with specific nested primers. The level of minimal residual disease (MRD) in the bone marrow (BM) and the peripheral blood (PB) may favor one of the two as the source for an autologous graft. In order to quantify MRD with RT-PCR we analyzed patients ficolled cells after limiting logarithmic dilutions in normal ficolled buffy-coat cells. In six patients with BCR-ABL-pos ALL who were in CR by conventional criteria (5 in CR1 and 1 in CR2), we studied a total of nine paired BM and PB samples prior to scheduled ABMT. A positive RT-PCR signals was detectable in all samples up to dilutions ranging from 1:10(1) to 1:10(3) in PB, and at higher titers ranging from 1:10(3) to 1:10(5) in the BM. The BM titers exceeded the corresponding PB titers in all nine sample pairs by at least 1 log. The mean difference was 1.55 log (geometric mean, n = 9) and is statistically significant (p < 0.03). We conclude that residual leukemia in BCR-ABL-positive ALL preferentially locates in the BM compartment, and we assume that PB may yield autologous grafts with significantly less leukemic contamination.