RESUMO
BACKGROUND: Traditional single-marker and multimarker molecular profiling approaches in bladder cancer do not account for major risk factors and their influence on clinical outcome. This study examined the prognostic value of molecular alterations across all disease stages after accounting for clinicopathological factors and smoking, the most common risk factor for bladder cancer in the developed world, in a population-based cohort. METHODS: Primary bladder tumors from 212 cancer registry patients (median follow-up, 13.2 years) were immunohistochemically profiled for Bax, caspase-3, apoptotic protease-activating factor 1 (Apaf-1), Bcl-2, p53, p21, cyclooxygenase-2, vascular endothelial growth factor, and E-cadherin alterations. "Smoking intensity" quantified the impact of duration and daily frequency of smoking. RESULTS: Age, pathological stage, surgical modality, and adjuvant therapy administration were significantly associated with survival. Increasing smoking intensity was independently associated with worse outcome (P < .001). Apaf-1, E-cadherin, and p53 were prognostic for outcome (P = .005, .014, and .032, respectively); E-cadherin remained prognostic following multivariable analysis (P = .040). Combined alterations in all 9 biomarkers were prognostic by univariable (P < .001) and multivariable (P = .006) analysis. A multivariable model that included all 9 biomarkers and smoking intensity had greater accuracy in predicting prognosis than models composed of standard clinicopathological covariates without or with smoking intensity (P < .001 and P = .018, respectively). CONCLUSIONS: Apaf-1, E-cadherin, and p53 alterations individually predicted survival in bladder cancer patients. Increasing number of biomarker alterations was significantly associated with worsening survival, although markers comprising the panel were not necessarily prognostic individually. Predictive value of the 9-biomarker panel with smoking intensity was significantly higher than that of routine clinicopathological parameters alone.
Assuntos
Biomarcadores Tumorais/análise , Fumar , Neoplasias da Bexiga Urinária/mortalidade , Idoso , Fator Apoptótico 1 Ativador de Proteases/metabolismo , Biomarcadores Tumorais/metabolismo , Caderinas/metabolismo , Estudos de Coortes , Seguimentos , Humanos , Los Angeles , Pessoa de Meia-Idade , Análise Multivariada , Valor Preditivo dos Testes , Prognóstico , Sistema de Registros , Resultado do Tratamento , Proteína Supressora de Tumor p53/metabolismo , Neoplasias da Bexiga Urinária/metabolismo , Neoplasias da Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/cirurgiaRESUMO
Immunohistochemistry (IHC), also referred to as immunocytochemistry in cytology literature, has revolutionized the practice of cytopathology. Because of the complexity of cytology preparation and limited diagnostic material, performing IHC remains a challenge. Formalin-fixed paraffin-embedded (FFPE) cell block (CB) is the optimal choice for IHC. In this review, the approaches for improving CB preparation will be discussed. When CB material is not available, various cytology specimens can also be used for IHC. With the utilization of Antigen Retrieval (AR) technique, these nonformalin-fixed cytology specimens can achieve successful IHC staining, comparable with the results from FFPE tissue sections. In the last part of this review, we will discuss the use of positive controls and the important role of AR in standardization of IHC in cytology.
Assuntos
Imuno-Histoquímica , Inclusão em Parafina , Humanos , Inclusão em Parafina/métodosRESUMO
This review article summarized recent advances in the heat-induced antigen retrieval technique with numerous scientific fields in addition to immunohistochemistry. Particularly, proteomics including imaging mass spectrometry, extraction of proteins from formalin-fixed, paraffin-embedded (FFPE) tissues. Some novel approaches such as FFPE tissue-based renal immunopathology based on modified double heating protocols are also introduced in this review for further development. In general, the FFPE tissue housed in pathology worldwide is an invaluable treasure, and the simple method of heat-induced antigen retrieval is the gold key to open the door of this treasure.
Assuntos
Antígenos/metabolismo , Imuno-Histoquímica/métodos , Rim/metabolismo , Animais , Antígenos/química , Calefação , Humanos , Rim/patologia , Espectrometria de Massas , Inclusão em Parafina , Proteômica , Fixação de TecidosRESUMO
To examine the use of acetone- or ethanol-fixed frozen tissue sections as the "gold standard" for immunohistochemical analysis, we evaluated frozen sections with various conditions of fixation and antigen retrieval (AR). Fresh human tissues were frozen in OCT. An adjacent tissue block was fixed in 10% neutral buffered formalin (NBF) and paraffin embedded (FFPE). Frozen sections were fixed by 6 protocols: acetone, ethanol, NBF (2 durations), and NBF + calcium chloride (2 durations). AR was used for all NBF-fixed sections. More than half of the antibodies (16/26 [62%]) showed immunohistochemical results indistinguishable between acetone- and NBF-fixed sections; 8 (31%) showed better immunohistochemical signals following NBF and AR; 2 gave better immunohistochemical results for acetone-fixed sections. Most cytoplasmic proteins (10/13) showed comparable immunohistochemical signals between acetone- and NBF-fixed sections. For nuclear proteins, NBF-fixed sections gave better immunohistochemical signals than did acetone-fixed sections. In most cases, NBF yielded stronger signals with less background and better morphology. The data do not support the use of acetone-fixed frozen tissue sections as the gold standard for immunohistochemical analysis. In evaluating new antibodies, a combination of acetone- and NBF-fixed frozen sections should be used, although in practice, FFPE tissue sections may serve as the standard for most antigens for immunohistochemical analysis.
Assuntos
Secções Congeladas/métodos , Imuno-Histoquímica/métodos , Imuno-Histoquímica/normas , Fixação de Tecidos/métodos , Acetona/normas , Western Blotting , Cloreto de Cálcio , Etanol/normas , Fixadores/normas , Formaldeído , Secções Congeladas/normas , Humanos , Fixação de Tecidos/normasRESUMO
From a practical point of view, one of the most difficult issues in the standardization of IHC for FFPE tissue is the adverse influence of formalin upon antigenicity, as well as the great variation in fixation/processing procedures. Based on previous study, an additional study using four markers demonstrated the potential for obtaining equivalent IHC staining among FFPE tissue sections with periods of formalin fixation ranging from 6 hr to 30 days. On this basis, the following hypothesis is proposed. "The use of optimized AR protocols permits retrieval of specific proteins (antigens) from FFPE tissues to a defined and reproducible degree (expressed as R%), with reference to the amount of protein present in the original fresh/unfixed tissue". This hypothesis may also be presented mathematically: the protein amount in a fresh cell/tissue, expressed as Pf, produces an IHC signal in fresh tissue of integral(Pf). When the identical IHC staining plus AR treatment is applied to a FFPE tissue section, the IHC signal may be represented as integral (Pffpe). The degree of retrieval after AR (R%) is calculated as follows: R% = integral (Pffpe)/ integral (Pf) x 100%. The amount of protein in the FFPE tissue may then be derived as follows: Pffpe = Pf x R%. In a situation where optimized AR is 100% effective, the IHC signal would then be of equal strength in fresh tissue and FFPE tissue, and Pffpe= Pf. Further studies are designed to test the limitations of the proposed hypothesis.
Assuntos
Antígenos/metabolismo , Fixadores , Formaldeído , Imuno-Histoquímica/normas , Inclusão em Parafina , Proteínas/metabolismo , Humanos , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
BACKGROUND: Induction of molecular chaperone Grp78 (78-kDa glucose-regulated protein) occurs in stress conditions that often characterize tumor microenvironments. We investigated the role of Grp78 in prostate cancer progression and the development of castration resistance, where cancer cells continue to survive despite the stress of an androgen-starved environment. EXPERIMENTAL DESIGN: Immunohistochemistry was done to examine Grp78 expression in 219 prostate cancers from patients with pathologic stage T3N0M0 disease [androgen ablation naive (untreated) and androgen ablation exposed (treated)] and castration-resistant prostate cancer. Classification of tumors was based on intensity of Grp78 cytoplasmic immunoreactivity and percentage of immunoreactive tumor cells. The associations of Grp78 expression with prostate cancer recurrence (clinical and/or serum prostate-specific antigen) and survival were examined in the untreated stage T3N0M0 group. Grp78 expression was also analyzed in the androgen-dependent LNCaP and castration-resistant C42B cell lines. RESULTS: The percentage of tumor cells expressing Grp78 was strongly associated with castration-resistant status (P = 0.005). Increased Grp78 expression was consistently associated with greater risk of prostate cancer recurrence and worse overall survival in patients who had not undergone prior hormonal manipulation. Grp78 expression was also increased in the castration-resistant LNCaP-derived cell line C42B and in LNCaP cells grown in androgen-deprived conditions compared with LNCaP cells grown in androgen-rich media. CONCLUSION: Our findings show that up-regulation of Grp78 is associated with the development of castration resistance, possibly in part by augmenting cell survival as previously suggested, and may serve as an important prognostic indicator of recurrence in a subset of patients with T3N0M0 disease.
Assuntos
Proteínas de Choque Térmico/genética , Chaperonas Moleculares/genética , Neoplasias da Próstata/genética , Estudos de Coortes , Chaperona BiP do Retículo Endoplasmático , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Estadiamento de Neoplasias , Orquiectomia , Neoplasias da Próstata/patologia , Neoplasias da Próstata/fisiopatologia , Estresse Fisiológico , Células Tumorais CultivadasRESUMO
A satisfactory protocol of protein extraction has been established based on the heat-induced antigen retrieval (AR) technique widely applied in immunohistochemistry for archival formalin-fixed, paraffin-embedded (FFPE) tissue sections. Based on AR, an initial serial experiment to identify an optimal protocol of heat-induced protein extraction was carried out using FFPE mouse tissues. The optimal protocol for extraction of proteins was then performed on an archival FFPE tissue of human renal carcinoma. FFPE sections were boiled in a retrieval solution of Tris-HCl containing 2% SDS, followed by incubation. Fresh tissue taken from the same case of renal carcinoma was processed for extraction of proteins by a conventional method using radioimmunoprecipitation assay solution, to compare the efficiency of protein extraction from FFPE tissue sections with extraction from fresh tissue. As a control, further sections of the same FFPE sample were processed by the same procedure without heating treatment. Evaluation of the quality of protein extracted from FFPE tissue was done using gel electrophoresis and mass spectrometry, showing most identified proteins extracted from FFPE tissue sections were overlapped with those extracted from fresh tissue.
Assuntos
Fixadores , Formaldeído , Inclusão em Parafina , Proteínas/isolamento & purificação , Animais , Eletroforese em Gel de Poliacrilamida , Calefação , Humanos , Concentração de Íons de Hidrogênio , Neoplasias Renais/química , Neoplasias Renais/ultraestrutura , Fígado/química , Glândulas Mamárias Humanas/química , Espectrometria de Massas , Camundongos , Controle de QualidadeRESUMO
PURPOSE: To determine the combined effects of p53, p21, and pRb alterations in predicting the progression of bladder transitional cell carcinoma. PATIENTS AND METHODS: p53, p21, and pRb expression was examined immunohistochemically on archival radical cystectomy samples from 164 patients with invasive or high-grade recurrent superficial transitional cell carcinoma (TCC; lymph node-negative, 117 patients; lymph node-positive, 47 patients). Median follow-up was 8.6 years. Based on percentage of nuclear reactivity, p53 was considered as wild-type (0% to 10%) or altered (>10%); p21 was scored as wild-type (>10%) or altered (<10%); and pRb status was considered wild-type (1% to 50%) or altered (0% or >50%). RESULTS: As individual determinants, the p53, p21, and pRb status were independent predictors of time to recurrence (P<.001, P<.001, and P<.001, respectively), and overall survival (P<.001, P=.002, and P=.001, respectively). By examining these determinants in combination, patients were categorized as group I (no alteration in any determinant, 47 patients), group II (any one determinant altered, 51 patients), group III (any two determinants altered, 42 patients), and group IV (all three determinants altered, 24 patients). The 5-year recurrence rates in these groups were 23%, 32%, 57%, and 93%, respectively (log-rank P<.001), and the 5-year survival rates were 70%, 58%, 33%, and 8%, respectively (log-rank P<.001). After stratifying by stage, the number of altered proteins remained significantly associated with time to recurrence and overall survival. CONCLUSION: This study suggests that alterations in p53, p21, and pRb act in cooperative or synergistic ways to promote bladder cancer progression. Examining these determinants in combination provides additional information above the use of a single determinant alone.
Assuntos
Carcinoma de Células de Transição/metabolismo , Ciclinas/metabolismo , Proteína do Retinoblastoma/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Neoplasias da Bexiga Urinária/metabolismo , Carcinoma de Células de Transição/patologia , Carcinoma de Células de Transição/terapia , Inibidor de Quinase Dependente de Ciclina p21 , Progressão da Doença , Seguimentos , Regulação Neoplásica da Expressão Gênica , Humanos , Prognóstico , Modelos de Riscos Proporcionais , Recidiva , Análise de Sobrevida , Neoplasias da Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/terapiaRESUMO
A serial study was performed to develop a protein-embedding technique for standardization of immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded (FFPE) tissue sections. A protein carrier matrix must have two phases, a liquid phase to allow uniform mixing of a protein and a solid phase forming a 'block' that can be fixed and processed in the same manner as human tissue. This standardized protein block would serve as a source of thin sections for control of IHC and therefore must also withstand the boiling conditions of antigen retrieval (AR). After multiple experiments, a method was developed utilizing polymer microsphere (beads) as a support medium for protein. The method showed particular promise for quantitative IHC.
Assuntos
Fixadores , Formaldeído , Imuno-Histoquímica/normas , Inclusão em Parafina , Proteínas/metabolismo , Animais , Anticorpos Monoclonais , Cabras , Cavalos , Queratinas/imunologia , Queratinas/metabolismo , Camundongos , Microesferas , Microtomia , Polímeros , Padrões de Referência , Proteínas S100/imunologia , Proteínas S100/metabolismoRESUMO
During the course of diagnostic surgical pathology, pathologists have established a large collection of formalin-fixed, paraffin-embedded tissues that form invaluable resources for translational studies of cancer and a variety of other diseases. Accessibility of macromolecules in the fixed tissue specimens is a critical issue as exemplified by heat-induced antigen retrieval (AR) immunohistochemical (IHC) staining. On the basis of observations that heating may also enhance in situ hybridization (ISH) and the similarity of formalin-induced chemical modifications that occur in protein and in DNA, we designed a study to examine the efficiency of DNA extraction from archival formalin-fixed, paraffin-embedded tissues using an adaptation of the basic principles of the AR technique, i.e., heating the tissue under the influence of different pH values. Archival paraffin blocks of lymph nodes, tonsil, and colon were randomly selected. Each paraffin block was prepared in 34 microtubes. For each paraffin block, one tube was used as a control sample, using a non-heating DNA extraction protocol. The other 33 tubes were tested using a heating protocol under 11 variable pH values (pH 2 to 12) under three different heating conditions (80, 100, and 120C). Evaluation of the results of DNA extraction was carried out by measuring yields by photometry and PCR amplification, as well as kinetic thermocycling (KTC)-PCR methods. In general, lower pH (acid) solutions gave inferior results to solutions at higher pH (alkaline). Heating tissues at a higher temperature and at pH 6-9 gave higher yields of DNA. There appeared to be a peak in terms of highest efficiency of extracted DNA at around pH 9. The average ratios 260:280 of extracted DNA also showed better values for samples heated at 120C. PCR products of three primers showed satisfactory results for DNA extracted from archival paraffin-embedded tissues by heating protocols at pH 6-12, with results that were comparable to the control sample subjected to the standard non-heating, enzymatic DNA extraction method. This study is the first to document the use of heating at an alkaline pH for DNA extraction from archival formalin-fixed, paraffin-embedded tissues, a recommendation based on the principles of AR for protein IHC. These findings may lead to a more effective protocol for DNA extraction from archival paraffin-embedded tissues and may also provide enhanced understanding of changes that occur during formalin-induced modification of nucleic acids.
Assuntos
Antígenos/isolamento & purificação , DNA/isolamento & purificação , Fixadores , Formaldeído , Antígenos/química , DNA/química , Fixadores/química , Formaldeído/química , Calefação , Humanos , Concentração de Íons de Hidrogênio , Inclusão em Parafina , Reação em Cadeia da Polimerase , Fixação de TecidosRESUMO
Antigen retrieval is now a standard procedure in immunohistochemical studies of tissues for diagnosis and research. While the most commonly used protocol (20 minutes at 100 degrees C in citrate buffer pH 6.0) is effective for many antibody/antigen combinations, experience has shown that in some instances, this standard approach fails. Under these circumstances, a successful antigen retrieval protocol may still be established by varying key conditions in the antigen retrieval process. The authors previously have advocated a test battery approach to determine the optimal conditions for antigen retrieval, illustrated here with respect to a polyclonal antibody to cyclooxygenase-2 (PG-27) that failed to give a positive staining result after orthodox antigen retrieval. The key feature of this modified antigen retrieval protocol is heating the deparaffinized tissue sections at a reduced temperature (90 degrees C as opposed to 100 degrees C). For this particular antibody, a boiling condition yields a negative result, a principal reason why previous investigators have used a tyramide signal amplification system to achieve satisfactory immunohistochemical results with this antibody. The optimal antigen retrieval protocol established in the authors' laboratory for this polyclonal antibody to cyclooxygenase-2 (PG-27) was evaluated in a study of formalin-fixed, paraffin-embedded cell lines and 31 bladder cancer tissue blocks using the tissue microarray technique, with side-by-side comparison between the results obtained by a tyramide signal amplification method (without antigen retrieval) and a standard immunohistochemical method with the optimized antigen retrieval protocol. The reduced temperature antigen retrieval protocol yielded a comparable or superior immunostaining for cyclooxygenase-2 both in cell lines and tissue blocks. In conclusion, use of the test battery approach allowed development of a modified antigen retrieval technique that provides a more reliable, much simpler approach for the demonstration of cyclooxygenase-2 in archival tissues.
Assuntos
Antígenos/metabolismo , Imuno-Histoquímica/métodos , Isoenzimas/imunologia , Isoenzimas/metabolismo , Prostaglandina-Endoperóxido Sintases/imunologia , Prostaglandina-Endoperóxido Sintases/metabolismo , Anticorpos , Neoplasias da Mama/enzimologia , Neoplasias da Mama/patologia , Ciclo-Oxigenase 2 , Feminino , Formaldeído , Temperatura Alta , Humanos , Masculino , Proteínas de Membrana , Inclusão em Parafina , Neoplasias da Próstata/enzimologia , Neoplasias da Próstata/patologia , Fixação de Tecidos , Células Tumorais Cultivadas , Neoplasias da Bexiga Urinária/enzimologia , Neoplasias da Bexiga Urinária/patologiaRESUMO
Tissue-based proteomic approaches (tissue proteomics) are essential for discovering and evaluating biomarkers for personalized medicine. In any proteomics study, the most critical issue is sample extraction and preparation. This problem is especially difficult when recovering proteins from formalin-fixed, paraffin-embedded (FFPE) tissue sections. However, improving and standardizing protein extraction from FFPE tissue is a critical need because of the millions of archival FFPE tissues available in tissue banks worldwide. Recent progress in the application of heat-induced antigen retrieval principles for protein extraction from FFPE tissue has resulted in a number of published FFPE tissue proteomics studies. However, there is currently no consensus on the optimal protocol for protein extraction from FFPE tissue or accepted standards for quantitative evaluation of the extracts. Standardization is critical to ensure the accurate evaluation of FFPE protein extracts by proteomic methods such as reverse phase protein arrays, which is now in clinical use. In our view, complete solubilization of FFPE tissue samples is the best way to achieve the goal of standardizing the recovery of proteins from FFPE tissues. However, further studies are recommended to develop standardized protein extraction methods to ensure quantitative and qualitative reproducibility in the recovery of proteins from FFPE tissues.
Assuntos
Fixadores/química , Formaldeído/química , Inclusão em Parafina/métodos , Parafina/química , Proteoma/análise , Biomarcadores/análise , Humanos , Reprodutibilidade dos TestesRESUMO
As a review for the 20th anniversary of publishing the antigen retrieval (AR) technique in this journal, the authors intend briefly to summarize developments in AR-immunohistochemistry (IHC)-based research and diagnostics, with particular emphasis on current challenges and future research directions. Over the past 20 years, the efforts of many different investigators have coalesced in extending the AR approach to all areas of anatomic pathology diagnosis and research and further have led to AR-based protein extraction techniques and tissue-based proteomics. As a result, formalin-fixed paraffin-embedded (FFPE) archival tissue collections are now seen as a literal treasure of materials for clinical and translational research to an extent unimaginable just two decades ago. Further research in AR-IHC is likely to focus on tissue proteomics, developing a more efficient protocol for protein extraction from FFPE tissue based on the AR principle, and combining the proteomics approach with AR-IHC to establish a practical, sophisticated platform for identifying and using biomarkers in personalized medicine.
Assuntos
Antígenos/isolamento & purificação , Diagnóstico , Imuno-Histoquímica/métodos , Animais , Antígenos/imunologia , Humanos , Imuno-Histoquímica/normas , Imuno-Histoquímica/tendências , Proteômica , Padrões de Referência , Fixação de TecidosRESUMO
INTRODUCTION: Retrospective studies suggest that p53 alteration is prognostic for recurrence in patients with urothelial bladder cancer and predictive for benefit from combination methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC) adjuvant chemotherapy. PATIENTS AND METHODS: Patients with pT1/T2N0M0 disease whose tumors demonstrated ≥ 10% nuclear reactivity on centrally performed immunohistochemistry for p53 were offered random assignment to three cycles of adjuvant MVAC versus observation; p53-negative patients were observed. By using a log-rank test with one-sided α = .05 and ß = .10, 190 p53-positive patients were planned to be randomly assigned to detect an absolute improvement in probability of recurring by 3 years from 0.50 to 0.30. RESULTS: A total of 521 patients were registered, 499 underwent p53 assessment, 272 (55%) were positive, and 114 (42%) were randomly assigned. Accrual was halted on the basis of the data and safety monitoring board review of a futility analysis. Overall 5-year probability of recurring was 0.20 (95% CI, 0.16 to 0.24) with no difference on the basis of p53 status. Only 67% of patients randomly assigned to MVAC received all three cycles with 12 patients receiving no treatment. There was no difference in recurrence in the randomly assigned patients (hazard ratio, 0.78; 95% CI, 0.29 to 2.08; P = .62). CONCLUSION: Neither the prognostic value of p53 nor the benefit of MVAC chemotherapy in patients with p53-positive tumors was confirmed, but the high patient refusal rate, lower than expected event rate, and failures to receive assigned therapy severely compromised study power.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células de Transição/tratamento farmacológico , Terapia de Alvo Molecular , Proteína Supressora de Tumor p53/metabolismo , Neoplasias da Bexiga Urinária/tratamento farmacológico , Idoso , Carcinoma in Situ/tratamento farmacológico , Carcinoma in Situ/genética , Carcinoma de Células de Transição/metabolismo , Cisplatino/administração & dosagem , Doxorrubicina/administração & dosagem , Feminino , Seguimentos , Humanos , Técnicas Imunoenzimáticas , Masculino , Metotrexato/administração & dosagem , Estudos Prospectivos , Taxa de Sobrevida , Resultado do Tratamento , Neoplasias da Bexiga Urinária/metabolismo , Vimblastina/administração & dosagemRESUMO
Formalin-fixed and paraffin-embedded tissues represent the vast majority of archived tissue. Access to such tissue specimens via shotgun-based proteomic analyses may open new avenues for both prospective and retrospective translational research. In this study, we evaluate the effects of fixation time on antigen retrieval for the purposes of shotgun proteomics. For the first time, we demonstrate the capability of a capillary isotachophoresis (CITP)-based proteomic platform for the shotgun proteomic analysis of proteins recovered from FFPE tissues. In comparison to our previous studies utilizing capillary isoelectric focusing, the CITP-based analysis is more robust and increases proteome coverage. In this case, results from three FFPE liver tissues yield a total of 4098 distinct Swiss-Prot identifications at a 1% false-discovery rate. To judge the accuracy of these assignments, immunohistochemistry is performed on a panel of 17 commonly assayed proteins. These proteins span a wide range of protein abundances as inferred from relative quantitation via spectral counting. Among the panel were 4 proteins identified by a single peptide hit, including three clusters of differentiation (CD) markers: CD74, CD117, and CD45. Because single peptide hits are often regarded with skepticism, it is notable that all proteins tested by IHC stained positive.
Assuntos
Antígenos/isolamento & purificação , Proteômica , Eletroforese Capilar , Formaldeído , Humanos , Inclusão em ParafinaRESUMO
OBJECTIVE: To investigate the role of potential downstream targets of HER-2/neu, including the cell-cycle regulator p27, proliferation-associated protein Ki-67, apoptosis inhibitor Bcl-2, and signal-transduction molecule Akt (which is associated with cell survival), as the development of androgen-independent prostate cancer (AIPC) in patients who are initially responsive to androgen-ablation therapy (AAT) is a significant clinical problem. PATIENTS AND METHODS: Earlier studies showed that high levels of HER-2/neu tyrosine kinase receptor expression as assessed by immunohistochemistry were significantly associated with the development of AIPC, and we hypothesised that HER-2/neu overexpression provides an alternative proliferative stimulus upon androgen depletion. We established a unique clinical model system, comprising patients who received no AAT, or who had preoperative AAT, or those with advanced tumours resistant to AAT. To test our hypothesis in vitro, we stably transfected full-length HER-2/neu cDNA in androgen-responsive LNCaP cells and examined the effects of HER-2/neu overexpression on cell proliferation, apoptosis, androgen-receptor activation, and Akt phosphorylation upon androgen deprivation by using immunohistochemistry and Western blot technique. RESULTS: p27 expression was initially induced on exposure to AAT, and significantly decreased in AIPC (P < 0.001). There was also a significant increase in the Ki-67 index in AIPC (P = 0.001). Elevated Bcl-2 expression was closely associated with AAT (P = 0.002), suggesting that Bcl-2 expression is induced on initial exposure to AAT. Further, Bcl-2 expression was highest in hormone-resistant cancers (P < 0.001). Using the HER-2/neu transfected cell-line model, we confirmed the mechanistic basis of the clinical observations which elucidate the pathway leading to HER-2/neu-mediated androgen independence. On androgen deprivation, the HER-2/neu transfected cells had higher proliferation rates, lower G1 arrest, inhibited p27 up-regulation, a lower apoptotic index, and higher Bcl-2, prostate-specific antigen and phosphorylated Akt expression than the mock-transfected LNCaP cells. CONCLUSION: This study suggests that prostate cancer cells undergo a series of coordinated changes after exposure to AAT, which eventually result in the development of androgen independence. Further, in support of previous results, it appears that a major factor in this process is the induction of HER-2/neu overexpression, which occurs after initial exposure to AAT. HER-2/neu may contribute to the development of androgen independence through: (i) maintaining cell proliferation; (ii) inhibiting apoptosis; and/or (iii) inducing AR activation in a ligand-independent fashion. These effects may be mediated, at least in part, through activation of the PI3K/Akt pathway.
Assuntos
Androgênios/metabolismo , Genes bcl-2/fisiologia , Antígeno Ki-67/metabolismo , Neoplasias Hormônio-Dependentes/metabolismo , Neoplasias da Próstata/metabolismo , Receptor ErbB-2/metabolismo , Receptores Androgênicos/metabolismo , Idoso , Antagonistas de Androgênios/uso terapêutico , Western Blotting , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Antígeno Prostático Específico/metabolismoRESUMO
Based on the antigen retrieval principle, our previous study has demonstrated that heating archival formalin-fixed, paraffin-embedded (FFPE) tissues at a higher temperature and at higher pH value of the retrieval solution may achieve higher efficiency of extracted DNA, when compared to the traditional enzyme digestion method. Along this line of heat-induced retrieval, this further study is focused on development of a simpler and more effective heat-induced DNA retrieval technique by testing various retrieval solutions. Three major experiments using a high temperature heating method to extract DNA from FFPE human lymphoid and other tissue sections were performed to compare: (1) different concentrations of alkaline solution (NaOH or KOH, pH 11.5-12) versus Britton and Robinson type of buffer solution (BR buffer) of pH 12 that was the only retrieval solution tested in our previous study; (2) several chemical solutions (SDS, Tween 20, and GITC of various concentrations) versus BR buffer or alkaline solution; and (3) alkaline solution mixed with chemicals versus BR buffer or single alkaline solution. Efficiency of DNA extraction was evaluated by measuring yields using spectrophotometry, electrophoretic pattern, semiquantitation of tissue dissolution, PCR amplification, and kinetic thermocycling-PCR methods. Results showed that boiling tissue sections in 0.1 M NaOH or KOH or its complex retrieval solutions produced higher yields and better quality of DNA compared to BR buffer or chemical solutions alone. The conclusion was that boiling FFPE tissue sections in 0.1 M alkaline solution is a simpler and more effective heat-induced retrieval protocol for DNA extraction. Combination with some chemicals (detergents) may further significantly improve efficiency of the heat-induced retrieval technique.