Biomedical subjects

Shan-Rong Shi

Publications and source records attributed to Shan-Rong Shi.

10 recordsLinked to original sources

PubMed2006

Expression of stress response protein Grp78 is associated with the development of castration-resistant prostate cancer.

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.

Cohort Studies↗

PubMed2006

Standardization of immunohistochemistry for formalin-fixed, paraffin-embedded tissue sections based on the antigen-retrieval technique: from experiments to hypothesis.

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.

Antigens↗

PubMed2006

Protein extraction from formalin-fixed, paraffin-embedded tissue sections: quality evaluation by mass spectrometry.

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.

Animals↗

PubMed2006

Role of coordinated molecular alterations in the development of androgen-independent prostate cancer: an in vitro model that corroborates clinical observations.

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.

Aged↗

PubMed2005

Protein-embedding technique: a potential approach to standardization of immunohistochemistry for formalin-fixed, paraffin-embedded tissue sections.

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.

Animals↗

PubMed2004

DNA extraction from archival formalin-fixed, paraffin-embedded tissues: heat-induced retrieval in alkaline solution.

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.

Antigens↗

PubMed2004

Combined effects of p53, p21, and pRb expression in the progression of bladder transitional cell carcinoma.

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.

Carcinoma, Transitional Cell↗

PubMed2004

Hyperphosphorylation of pRb: a mechanism for RB tumour suppressor pathway inactivation in bladder cancer.

Loss of heterozygosity, mutations or deletions of the RB1 gene usually result in loss of pRb expression, which has been regarded as an indicator of loss of pRb function in human tumours. It has previously been shown that in addition to loss of pRb expression, aberrantly high (pRb2+) pRb expression also indicates loss of pRb function in bladder tumours compared with moderate (normal, pRb1+) pRb expression. The aim of this study was to elucidate the mechanism by which pRb is functionally inactivated in bladder tumours expressing aberrantly high levels of pRb. Constitutive phosphorylation was therefore investigated as a mechanism of pRb inactivation in bladder tumours. Of 28 bladder tumours examined, western blotting demonstrated pRb hyperphosphorylation in 5/7 (71%) pRb2+ bladder tumours compared with only 4/11 (36%) pRb1+ tumours (p = 0.002). All cases with undetectable pRb showed moderate to high p16 expression and none showed cyclin D1 expression by immunohistochemistry. All pRb1+ tumours with underphosphorylated pRb showed p16 but not cyclin D1 expression. All pRb2+ tumours with hyperphosphorylated pRb showed loss of p16 expression and/or cyclin D1 overexpression. Thus, elevated pRb expression was associated with pRb hyperphosphorylation, which, in turn, was associated with loss of p16 expression and/or increased cyclin D1 expression. In order to analyse this association in vitro, T24 cells, which express high levels of pRb, were transfected with p16 cDNA. Transfection with p16 cDNA resulted in a marked decrease in pRb phosphorylation, decreased cell proliferation, and a change in expression of pRb from high to moderate phenotype as assessed by immunohistochemistry. This paper gives the biological basis for constitutive alteration of pRb function in human tumours in the presence of an intact, expressed pRb protein; the mechanism of pRb inactivation is through hyperphosphorylation, which results from loss of p16 expression and/or cyclin D1 overexpression. Immunohistochemical expression of pRb appears to be a reliable indicator of pRb function.

Blotting, Western↗

PubMed2002

A modified reduced-temperature antigen retrieval protocol effective for use with a polyclonal antibody to cyclooxygenase-2 (PG 27).

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.

Antibodies↗

PubMed2002

DNA extraction from archival formalin-fixed, paraffin-embedded tissue sections based on the antigen retrieval principle: heating under the influence of pH.

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.

Antigens↗