Biomedical subjects

W F Benedict

Publications and source records attributed to W F Benedict.

At least 37 records · Page 2Linked to original sources

PubMed1997

Retinoblastoma protein expression and radiation response in muscle-invasive bladder cancer.

PURPOSE: The retinoblastoma protein (pRB) is a key regulator of the G1 cell cycle checkpoint and has been implicated as having a role in G1 arrest and apoptosis induced by radiation damage. In this report we examine the association between pRB expression and radiation response in patients treated between 1960 and 1983 with preoperative radiotherapy (50 Gy in 25 fractions) followed 4-6 weeks later by radical cystectomy. The correlation of pRB to patient outcome and how this relationship is complimentary to that seen with p53 staining status is also described. METHODS AND MATERIALS: Immunohistochemical staining of pRB and p53 in paraffin-embedded tumor sections using WL-1 anti-RB and DO1 anti-p53 antibodies was considered adequate in 98 and 97 pretreatment tumor samples, respectively. There were 46 patients with clinical Stage T2, 28 with Stage T3a, and 24 with Stage T3b disease. The median age was 62 years and follow-up for those living was 85 months. RESULTS: Staining for pRB was negative in 30% of the cases. Correlations were observed between pRB negativity and high pretreatment apoptosis level (p = 0.06), locally advanced clinical stage (p = 0.01), increased clinical-to-pathologic downstaging (p = 0.014), and more pathologic complete responses (Path-CRs; p = 0.019). Several other factors were tested and were not associated with pRB status, including p53 expression. RB status was the only pretreatment prognostic factor in the univariate analyses that correlated with downstaging and was independently associated with Path-CR using multivariate logistic regression. Despite these significant relationships, no correlations with patient outcome were observed when the entire cohort was analyzed. Restriction of the analyses to Stage T3b patients, however, revealed that pRB negativity predicted for enhanced distant metastasis freedom (p = 0.006, log rank) and overall survival (p = 0.02). The overexpression of p53 also correlated with distant metastasis freedom and overall survival in Stage T3b patients. Patient outcome was best when RB negative and p53 negative staining were seen. CONCLUSION: Our results indicate that loss of RB function as measured by immunohistochemical staining is the strongest correlate of radiation response thus far recognized. Loss of RB expression also predicted for poor outcome in Stage T3b patients, which appeared to compliment the finding of normal p53 expression. While normal RB protein expression is usually associated with better patient outcome, other series have not examined patients treated with radiotherapy. The absence of pRB may be a useful marker for selecting patients for bladder preservation with radiotherapy, particularly when wild-type p53 is present.

Adult↗

PubMed1997

Altered retinoblastoma protein expression in nonsmall cell lung cancer: its synergistic effects with altered ras and p53 protein status on prognosis.

BACKGROUND: Inactivation of the retinoblastoma (Rb) gene has been documented in various types of cancer, including lung cancer. Alterations of the p53 and ras genes are also common features in the molecular biology of lung carcinoma, and the authors of this article have reported previously on the prognostic significance of both of them. In the present study, the authors evaluated the prognostic significance of the loss of Rb protein expression alone, then performed a combined analysis of Rb protein and ras p21 status (Rb/ras) as well as an analysis of Rb and p53 protein status (Rb/p53) in patients with nonsmall cell lung cancer (NSCLC). METHODS: Ninety-one patients with NSCLC underwent potentially curative resection between 1977 and 1988, 65 of whom received postoperative combination chemotherapy. Tumor specimens were analyzed for Rb protein expression by immunohistochemistry. Univariate and multivariate analyses were performed to assess the association between Rb protein expression and survival. RESULTS: Nineteen (21%) of the 91 NSCLCs showed negative Rb protein expression. Positive or negative Rb protein expression (Rb+ or Rb-) as an individual factor was not statistically correlated with survival or prognosis in this cohort of NSCLC patients, although a tendency among Rb- patients to do worse was observed. The authors then combined the Rb protein status with previously studied results of ras p21 and p53 protein expression in the same tumor specimens, and compared the prognosis between the individuals with theoretically the best pattern of gene expression in their tumors and those with theoretically the worst pattern of expression, i.e., Rb+/ras- versus Rb-/ras+ and Rb+/p53- versus Rb-/p53+. In patients with adenocarcinoma, those with Rb-/ras+ tumors survived for a significantly shorter period after surgery (13% 5-year survival) than those with Rb+/ras- tumors (82% 5-year survival) (P = 0.01). Similarly, patients with Rb-/p53+ tumors survived for a significantly shorter period (20% 5-year survival) compared with those who had Rb+/p53- tumors (73% 5-year survival) (P = 0.008). Rb/ras status was a significant prognostic factor (P = 0.02 by univariate analysis, P = 0.048 by multivariate analysis), and Rb/p53 status tended to be significant as a prognostic factor (P = 0.04 by univariate analysis, P = 0.08 by multivariate analysis). In patients with squamous cell carcinoma, neither Rb/ras nor Rb/p53 status was a significant prognostic factor in this cohort. CONCLUSIONS: These results suggest that combined immunohistochemical analyses of Rb and ras p21 proteins and of Rb and p53 proteins may indicate their potentially synergistic effects on survival and prognosis. These analyses may also be useful for stratifying patients with adenocarcinoma of the lung into different prognostic groups and identifying populations with different risks of recurrence. Larger prospective studies with Stage I NSCLC patients are necessary to confirm the current findings.

Adenocarcinoma↗

PubMed1997

Cooperative effects of p53 and pRB alterations in primary superficial bladder tumors.

Altered patterns of p53 and pRB expression have been reported to be frequent events and to have prognostic significance in bladder cancer. To assess the potential adverse consequences of having altered patterns of both p53 and pRB proteins in patients with bladder neoplasms compared with having one or neither abnormality, we have studied a cohort of superficial transitional cell carcinomas of the urinary bladder by immunohistochemical analysis. The present study included 59 well-characterized superficial transitional cell carcinomas (Ta, n = 28; T1, n = 31) for which clinicopathological variables were available. Nuclear overexpression of p53 was identified in 22 cases (37%). A statistically significant association was observed between the p53-positive phenotype and disease progression (P < 0.001), as well as reduced survival (P < 0.001). Undetectable levels of pRB were observed in 11 cases (19%). Patients with a pRB-negative phenotype had a more frequent disease progression (P = 0.014) and decreased overall survival (P = 0.014). We also observed a significant association between altered p53 and undetectable pRB expression patterns (P = 0.001). Nine tumors showed both a p53-positive and a pRB-negative phenotype. There was an even more marked increase in progression (P = 0.00005) and decreased overall survival (P = 0.0004) in patients whose tumors had both alterations after controlling for tumor stage, tumor grade, and suspicion of vascular invasion. These data suggest that alterations of p53 and pRB have a cooperative negative effect on both progression and survival in primary bladder cancer. It may be postulated that aberrant p53 and pRB expression deregulates cell cycle control at the G1 checkpoint and engenders tumor cells with reduced response to programmed cell death. The imbalance produced by an enhanced proliferative activity and a decreased apoptotic rate may determine the aggressive clinical course of the bladder tumors harboring both p53 and pRB alterations.

Carcinoma, Transitional Cell↗

PubMed1997

Deletion of three distinct regions on chromosome 13q in human non-small-cell lung cancer.

We examined loss of heterozygosity (LOH) at the retinoblastoma susceptibility gene (RB1) locus on chromosome 13q14 in 20 non-small-cell lung cancers (NSCLCs) using polymorphic markers. The expression of RB protein was examined by immunohistochemical analysis of paraffin-embedded specimens of the same tumors. The results revealed that 10 of 16 informative cases showed an LOH at the RB1 locus, whereas only 2 of the 10 tumors lost expression of the RB protein. These 2 tumors had mutations in the remaining RB1 allele. Thus, inactivation of the RB1 gene appears to be involved in a small subset of NSCLCs only. To elucidate the presence of tumor-suppressor genes other than RB1 on 13q, heterozygosity at 15 different loci was investigated. Of 20 tumors analyzed, 15 showed an LOH at least at one locus, and the regions 13q12.1-qter, 13q12.2-14.2 and 13q14.1-q14.3, including the RB1 locus, were deleted in significant numbers of the tumors. Our results suggest that, in addition to the RB1 gene, abnormalities of other tumor-suppressor genes on chromosome 13q are involved in the development of human NSCLCs.

Carcinoma, Non-Small-Cell Lung↗

PubMed1997

Loss of retinoblastoma gene function and heterozygosity at the RB locus in renal cortical neoplasms.

Alteration of the retinoblastoma (RB) gene, located on chromosome 13q14, has been implicated in the pathogenesis and biological behavior of several human cancers. We investigated the RB gene status by Western blotting and immunohistochemical analysis, as well as loss of heterozygosity (LOH) at the RB locus in 21 primary human renal neoplasms (including 3 oncocytomas). In only 1 of 21 tumors was there a discrepancy between Western blot and immunochemical staining. Overall, LOH was noted in 6 of 12 informative cases. However, only one of the tumors with LOH at the RB locus had loss of RB protein expression by both Western blot and immunohistochemical analysis. Loss of RB function was found in 4 of 18 carcinomas and in none of 3 oncocytomas as determined by absent RB nuclear staining in tumor cells. LOH at chromosome 13q14 was more noted in high-grade, DNA aneuploid, high-stage tumors and in patients with poor outcome. These results imply that (1) there is likely another tumor-suppressor gene on chromosome 13 involved in renal carcinogenesis, (2) LOH at chromosome 13q loci may be associated with aggressive behavior, and (3) the loss of RB function may have a role in a subset of renal carcinomas.

Adult↗

PubMed1997

Mantle cell lymphoma: correlation of clinical outcome and biologic features with three histologic variants.

PURPOSE: Clinical data and histologic material were retrospectively analyzed in 46 cases of previously untreated mantle cell lymphoma (MCL) to more fully characterize the clinical response pattern of these lymphomas and to determine whether growth pattern significantly affected clinical outcome. MATERIALS AND METHODS: The histologic pattern was classified as diffuse (61%), nodular (13%), and mantle zone (26%) in accordance with stated criteria. RESULTS: Bone marrow infiltration was detected in 69% of cases; the frequency of involvement correlated with histologic pattern, being most common in diffuse variants and least common in mantle zone variants. Other sites of extranodal involvement were observed in 50% of cases. Cyclin-D1 staining revealed nuclear positivity in 23 of 25 patients (92%) and no difference was observed between the various histologic patterns. Rearrangement at the bcl-1 major translocation cluster (MTC) was detected in seven of 21 cases, without regard for histologic pattern. Complete response rates to doxorubicin-based regimens showed a striking correlation with histologic pattern. Seventy-three percent of patients with a mantle zone pattern attained a complete response compared with only 25% of patients with a nodular pattern and 19% with a diffuse pattern. Three-year survival rates were 100%, 50%, and 55% for patients with mantle zone, nodular, and diffuse histologic patterns, respectively. CONCLUSION: We conclude that (1) diffuse and nodular MCL are associated with a poor treatment response and a poor overall survival rate; (2) the mantle zone variant exhibits the clinical attributes of a low-grade lymphoma; and (3) the poor survival rates of patients with nodular and diffuse MCL suggest that these variants be classified as intermediate-grade lymphomas. However, the trend of the time to treatment failure curve does not indicate that current regimens can cure MCL.

Adult↗

PubMed1997

Differential retinoblastoma protein expression in neuroendocrine tumors of the lung. Potential diagnostic implications.

Neuroendocrine lung tumors have been considered by some to be a continuum ranging from relatively benign typical carcinoids to highly malignant small-cell carcinomas. Histopathological diagnosis may sometimes be difficult because of their overlapping features. Correct classification, however, carries important prognostic and therapeutic significance. To determine the clinicopathological implications of retinoblastoma (RB) protein expression in these neoplasms, we examined the RB status in a series of neuroendocrine tumors by immunohistochemical analysis of paraffin-embedded tissue sections. A total of 105 tumors were studied. All 44 typical and 15 atypical carcinoids, one of which was initially misdiagnosed as a small-cell carcinoma, manifested a heterogeneous RB-positive staining pattern. Atypical carcinoids in general showed an increase in the number of tumor cells with strong nuclear staining compared to typical carcinoids. In contrast, all 40 small-cell and 6 large-cell neuroendocrine carcinomas failed to show RB staining in any tumor nuclei, indicating loss of RB function. Our results suggest that RB status as measured by immunohistochemical staining can be used as a marker to distinguish typical and atypical carcinoids from small-cell and large-cell neuroendocrine carcinomas.

Carcinoid Tumor↗

PubMed1997

Abnormal bcl-2 and pRb expression are independent correlates of radiation response in muscle-invasive bladder cancer.

The objective of this study was to determine whether the overexpression of bcl-2, a key protein governing the apoptotic response to radiation, adds to pRb status in estimating the propensity for radiation response in patients with muscle-invasive bladder cancer. Archival formalin-fixed, paraffin-embedded, pretreatment bladder tumor samples were available in 109 of 301 patients treated preoperatively with 50 Gy in 25 fractions followed by radical cystectomy 4-6 weeks later. Radiation response was assessed by clinical-to-pathological tumor downstaging or upstaging. Altered expression of bcl-2 (47% of 107 patients), p53 (56% of 109 patients), and pRb (30% of 98 patients) was assessed by immunohistochemical staining. Morphological criteria were used to calculate the percentage of apoptotic cells. bcl-2 staining correlated with tumor grade; all grade 2 tumors (n = 7) displayed normal bcl-2 expression (negative staining). No correlations between bcl-2 staining and pretreatment apoptosis levels, p53 staining, and pRb staining were observed. In terms of the radiation response parameters, univariate analyses revealed that bcl-2 overexpression was the only factor associated with upstaging. The main predictor of downstaging was the loss of pRb expression (negative staining). Multivariate logistic regression confirmed these findings and also showed that normal pRb expression (positive staining) was significantly related to upstaging. Patient outcome was adversely affected by bcl-2 overexpression, because these patients experienced significantly increased actuarial local failure rates. No difference in distant metastasis or survival rates by bcl-2 staining was seen. The strongest independent correlates of radiation response thus far identified in muscle-invasive bladder cancer are from bcl-2 and pRb immunohistochemical staining. The overexpression of bcl-2 and the normal expression of pRb seem to thwart the apoptotic response to radiation via independent mechanisms. Abnormalities in the expression of proteins that regulate apoptosis may prove to establish a molecular phenotype to characterize which patients should receive radiotherapy.

Actuarial Analysis↗

PubMed1996

Expression of the retinoblastoma (RB) tumor suppressor gene inhibits tumor cell invasion in vitro.

To determine if replacement of the retinoblastoma (RB) tumor suppressor gene could inhibit invasion of RB-defective tumor cells, the capacity of tumor cells to migrate or invade was quantitated by the Boyden chamber assay. The studies were done in a diverse group of stable RB-reconstituted human tumor cell lines, including those derived from the osteosarcoma and carcinomas of the lung, breast and bladder. The expression of the exogenous wild-type RB protein in these tumor cell lines was driven by either a constitutively active promoter or an inducible promoter. It was found that significantly more tumor cells from the parental RB-defective cell lines and the RB revertants than from the RB-reconstituted RB+ cell lines penetrated through the Matrigel (P<0.001, two-tailed t-test), although both RB+ and RB- cells migrated at approximately the same rate on uncoated polycarbonate filters in the Boyden chambers. Of note, the inhibition of invasiveness of various RB-defective tumor cells by RB replacement was apparently well correlated with suppression of their tumorigenicity in vivo. In contrast, although either functional RB or p53 re-expression effectively suppressed tumor formation in nude mice of the RB-/p53null osteosarcoma cell line, Saos-2, replacement of the wild-type p53 gene had much less impact on their invasiveness as compared to the RB gene. These studies provided an insight into the broader biological basis of the RB-mediated tumor suppression in RB-defective tumor cells.

Animals↗

PubMed1996

p53, Rb, and cyclin D1 expression in human oral verrucous carcinomas.

BACKGROUND: The verrucous carcinoma (VC), a tumor with low grade malignancy, appears to be associated with tobacco and human papillomavirus. The pathobiology of these tumors has not been extensively studied, and molecular genetic alterations have not been reported. In this study we investigated by immunohistochemistry the expression of p53, Rb, and cyclin D1 in a series of well-defined oral VC. Changes in the expression of these genes have been commonly reported in a variety of human tumors. METHODS: We studied 29 cases of VC, fixed in formalin and embedded in paraffin. Immunohistochemistry was carried out using the avidin-biotin immunoperoxidase technique. Polyclonal antibody CM-1 was used for p53, a rabbit polyclonal human RB antibody, Rb-WL-1 antibody for Rb and a rabbit polyclonal human cyclin D antibody for cyclin D1. RESULTS: Positive p53 expression (protein accumulation) was detected in 15 of the 29 VC analyzed. In some cases, p53-positive areas were small foci but in most of the cases extensive positive areas were observed. None of the cases studied showed alterations of Rb protein. The expression of cyclin D1 was determined in 18 cases of VC. Positive nuclear immunostaining was seen in 11 cases. CONCLUSIONS: p53 protein accumulation is frequently observed in these tumors suggesting possible mutations of this gene in VC. Overexpression of cyclin D1 but no alterations of Rb staining were also observed in this low grade tumor suggesting that Rb may be functionally inactivated by overexpression of cyclin D1 or HPV infection.

Adult↗

PubMed1996

Expression of the retinoblastoma protein in low-grade B-cell lymphoma: relationship to cyclin D1.

The product of the retinoblastoma tumor-suppressor gene (pRB), a nuclear phosphoprotein that regulates transcription factors such as E2F, is involved in cell cycle control and differentiation. Its activity is regulated by phosphorylation; the underphosphorylated form inhibits transcription whereas the highly phosphorylated form is inactive. Cyclin D1 and its associated kinase (CDK 4/6) phosphorylate pRB in vitro, and therefore are thought to contribute to the regulation of pRB function. To examine the effect of cyclin D1 overexpression on pRB in primary tumor tissue, we studied pRB expression in low-grade B-cell neoplasms, with particular regard to mantle cell lymphoma, which is characterized by cyclin D1 (bcl-1) overexpression. pRB expression was studied by immunostaining with a well-characterized anti-pRB antibody; the phosphorylation status of pRB was examined by immunoblots; and the functional binding capacity of pRB was examined by in vitro binding to adenovirus E1A protein. We studied 3 reactive lymph nodes, 28 low grade B-cell lymphomas, 4 cases of hairy cell leukemia (HCL) and 3 plasmacytomas. Reactive lymph nodes showed intense pRB staining of germinal centers, with strongest (2+) staining in the large cells (centroblasts) of the proliferating (dark) zone and weak or no staining of small lymphocytes, including those of the mantle zone. In B-chronic lymphocytic leukemia (B-CLL) (4 cases), follicular lymphoma (3 cases) and mucosa-associated (MALT) lymphoma (3 cases) strong (2+) pRB staining was limited to centroblasts in reactive and neoplastic follicles and occasional proliferation centers, with only faint staining of small lymphoid cells. In contrast, 15 of 16 cases of mantle cell lymphoma showed strong (1-2+) staining of most cells; one blastoid mantle cell lymphoma showed only faint pRB staining. All cases of (HCL) and plasmacytoma showed strong pRB staining. Although most lymphomas with strong pRB expression were cyclin D1(+), three cyclin D1(+) cases showed only weak pRB expression (1 B-CLL, 1 blastoid mantle cell, 1 unclassifiable low grade B-cell lymphoma). Conversely, of the 4 pRB(+) HCLs and 3 pRB(+) plasmacytomas, only 1 of each was cyclin D1(+). pRB appeared to exist primarily in the underphosphorylated (fastest migrating) form on Western blot, despite the fact that cyclin D1 was complexed to CDK4, a form in which it normally phosphorylates pRB. In addition, pRB appeared to be unmutated, because it bound normally to the adenovirus E1A protein and showed nuclear localization by immunostaining. We conclude that most cases of mantle cell lymphoma, HCL, and plasmacytoma show high levels of pRB in contrast to follicle center lymphoma and small lymphocytic lymphoma; however, pRB expression does not appear to be consistently related to cyclin D1 overexpression. The pRB appears to be unmutated and underphosphorylated, and therefore should be in its active form. Our data from primary lymphoma tissue suggests that overexpression of cyclin D1, whereas tumorigenic, does not lead to pRB loss or hyperphosporylation. Thus, the mechanism by which cyclin D1 contributes to tumorigenesis and the significance of the restricted expression of pRB in low-grade lymphoid neoplasms remain to be determined.

Amino Acid Sequence↗

PubMed1996

Enhanced tumor suppressor gene therapy via replication-deficient adenovirus vectors expressing an N-terminal truncated retinoblastoma protein.

The preclinical studies presented here demonstrate that treatment of human non-small cell lung carcinoma and bladder carcinoma cells by a recombinant adenovirus vector, AdCMVpRB94, expressing the N-terminal truncated retinoblastoma (RB) protein (pRB94) completely suppressed the tumorigenicity of the treated tumor cells in nude mice. Furthermore, gene therapy of established human RB- and RB+ bladder xenograft cancers in nude mice by AdCMVpRB94 resulted in regression of the treated tumors. Of note, although both the full-length and the truncated forms of the RB protein, when overexpressed in tumor cells via replication-deficient adenovirus vectors, were capable of suppression of tumor growth, the pRB94 was evidently more potent than the full-length RB protein.

Adenoviruses, Human↗

PubMed1996

Development of an optimal protocol for antigen retrieval: a 'test battery' approach exemplified with reference to the staining of retinoblastoma protein (pRB) in formalin-fixed paraffin sections.

The retinoblastoma (RB) gene, which encodes the nuclear RB protein (pRB), is believed to be involved in cell cycle control and cell differentiation. Studies have demonstrated that loss of RB function may play a role in tumour formation and progression of a variety of human tumours, such as bladder, lung, breast, and prostate cancers. The immunohistochemical detection of pRB expression in formalin-paraffin sections of human cancer has potential advantages of convenience, economy, and compatibility with routine surgical pathology practice. In practice, however, results using pRB antibodies on routinely processed, paraffin-embedded tissue have been inconsistent. In this study, the antigen retrieval (AR) method has been applied to the immunohistochemical detection of pRB in paraffin-embedded tissues and a 'test battery' approach has been developed to identify the principal variables that result in the optimal AR protocol. This approach includes the use of buffered solutions at pH 1, 6, and 10 with three different heating conditions (temperatures 120 degrees C, 100 degrees C, and 90 degrees C). In the example described here with antibody RB-WL-1, the low pH solution with the microwave heating at 100 degrees C proved most effective. Both fresh and routinely processed formalin-paraffin tissues of normal and bladder carcinoma were used for a comparison of the pRB immunostaining. The AR method was evaluated by comparing the immunohistochemical staining result on routinely processed formalin-paraffin sections with frozen sections of the same tumour. A consistent intensity of immunohistochemical staining for pRB was achieved using the identified optimal AR protocol on formalin-paraffin sections. All slides showed positive staining of pRB in normal mesenchymal and epithelial tissues. The pattern of pRB localization and intensity of staining was similar to that obtained in frozen sections, though the intensity obtained by AR treatment on paraffin sections was slightly to moderately stronger than that obtained in frozen sections. Once the protocol was identified, it was tested using routinely processed paraffin tissue sections of 245 cases of bladder carcinoma, with consistent pRB immunostaining results. The protocol described is simple to perform and gives reproducible results for evaluation of pRB expression by immunohistochemistry.

Cryopreservation↗

PubMed1996

Cytogenetic responses to G2 phase x-irradiation of cells from retinoblastoma patients.

Fibroblast cell lines from 20 retinoblastoma (RB) patients with the hereditary bilateral form of disease compared with 16 lines from normal donors had a significantly higher chromatid aberration frequency (CAF), and more displaced and nondisplaced breaks per 100 metaphase cells after x-irradiation during the G2 phase of the cell cycle. The mean CAF was 39 +/- 1.0, range 30-46, for cells from normal subjects, compared to a mean of 245.6, range 101-506, for cells from hereditary RB patients (p < 10(-6). Of fibroblast lines from eight patients with unilateral RB, four had a CAF comparable to that of lines from normal donors (< 60) and four had a high CAF (> 130), resembling that of hereditary forms; two of the latter four lines were from patients with familial or deletion 13 forms of RB. Furthermore, in two families, PHA-stimulated blood lymphocytes from RB patients, one bilateral and one unilateral, and from certain unaffected first-degree relatives after G2 phase X-irradiation had a high CAF (> or = 110) compared to a CAF (> or = 53) of cells from three normal donors sampled at the same time. These results were shown not to be related to differences in cell cycle progression or initial extent of chromatid damage. The results suggest that the high frequency of chromatid aberrations in the cells from hereditary RB patients results from a genetic deficiency in DNA repair.

Adult↗

PubMed1996

Prognostic value of p53 in muscle-invasive bladder cancer treated with preoperative radiotherapy.

OBJECTIVES: The relationship of p53 mutations as analyzed immunohistochemically to radiation response and therapeutic outcome was examined in a cohort of 301 patients with muscle-invasive transitional cell carcinoma of the bladder treated relatively uniformly with preoperative radiotherapy (50 Gy in 25 fractions) 4 to 6 weeks prior to radical cystectomy. METHODS: Adequate formalin-fixed paraffin-embedded archival tissue for the immunohistochemical staining of p53 using antibody DO1 was obtained in 109 patients. The median follow-up for those living was 91 months. RESULTS: Overall, p53 staining was positive in 56% of the cases, with 60% positive in Stage T2 (n = 48), 42% in Stage T3a (n = 31), and 63% in Stage T3b (n = 30). Overexpression of p53 did not correlate with actuarial local control, distant metastasis freedom, disease freedom, or overall survival. However, significant associations were seen when these analyses were limited to patients with clinical Stage T3b disease. In this subgroup, the actuarial 5-year rates for patients with p53 positively and negatively stained tumors were 55% and 100%, respectively, for distant metastasis freedom (P = 0.01), 51% and 91% for disease freedom (P = 0.04), and 32% and 91% for overall survival (P = 0.006). Cox proportional hazards models that included p53 staining and other prognostic factors of significance in the univariate analyses revealed p53 to be independently predictive of survival for patients with Stage T3b disease. CONCLUSIONS: The prognostic value of p53 immunostaining rested with Stage T3b patients. Although no correlations were found with radiation response, p53 positivity in this subgroup was associated with a higher rate of distant metastasis and reduced overall survival. For these patients, p53 negativity would indicate that aggressive local treatment (that is, preoperative radiotherapy and cystectomy) is sufficient, whereas p53 positivity would indicate that multiagent chemotherapy is required because of the increased risk of distant metastasis.

Carcinoma, Transitional Cell↗

PubMed1996

Immunohistochemical detection of p53, bcl-2, and retinoblastoma proteins in follicular lymphoma.

Mutations of p53 have been suggested to be involved in the histologic transformation of follicular lymphoma, but the role of the retinoblastoma (RB) gene, another tumor suppressor gene, in lymphomagenesis has not been established. To determine the roles of these tumor suppressor genes and their relationship with the anti-apoptotic bcl-2 gene in follicle center lymphoma, the immunohistochemical expression of p53, bcl-2, and RB proteins was correlated with cytologic grade in 50 cases of follicular lymphoma, and the results were compared to 23 cases of diffuse large B-cell lymphoma. The results showed that only 2 of 25 grade 1 follicular lymphoma were p53-positive compared to 16 of 25 grade 3 cases (P <.0001). A significantly lower number (13 of 25) of grade 3 follicular lymphomas expressed bcl-2 compared to grade 1 cases (23 of 25) (P <.004). Eight of 14 bcl-2-negative follicular lymphomas expressed p53, compared with 10 of 36 bcl-2-positive cases (P = .1). Twenty-four of 25 grade 3 follicular lymphomas showed 2+ to 3+ staining for RB protein compared to 9 of 21 grade 1 cases (P <.0002). Expression of p53 protein correlates significantly with higher cytologic grade in follicular lymphoma. Similar to earlier studies of breast cancer and lymphoma, there appears to be an inverse relationship between p53 and bcl-2 expression in follicular lymphoma. Inactivation of the retinoblastoma gene does not seem to be involved in the histogenesis of follicle center lymphoma or diffuse large B-cell lymphoma.

Antibodies↗

PubMed1996

Altered retinoblastoma and p53 protein status in non-small cell carcinoma of the lung: potential synergistic effects on prognosis.

Routinely processed pathological specimens from 119 patients with stage I and II adenocarcinomas or squamous cell carcinomas were examined by immunohistochemical analysis for altered retinoblastoma (RB) and/or p53 protein expression. Absent RB nuclear staining (RB-) indicating loss of RB function occurred in 19 (16%) of the cases studied, whereas expression of a putative mutant p53 nuclear protein (p53(+)) was found in 54 (45%) of the tumors. The median survival was 39 versus 12 months for patients with RB+ and RB- tumors, respectively (P = 0.05 by log rank analysis). Similarly, the median survival was 41 months for patients whose tumors had no expression of mutant p53 (p53(-)) compared with 24 months for individuals with p53 (+) tumors (P = 0.01). These differences in survival, however, were not statistically significant by multivariate analysis. Nevertheless, individuals with RB-/p53(+) tumors had a significantly shorter median survival (12 months) than those with RB+/p53(-) tumors (41 months), as determined by both log rank and multivariate analyses (P = 0.005 and 0.03, respectively). In addition, 66 large cell carcinomas from all stages were examined. Again, a more significant difference in survival (48 versus 8 months) was found between patients with RB+/p53(-) versus RB-/p53(+) tumors (P = 0. 006). These results suggest that RB and p53 status might be used synergistically as prognostic factors in a subset of non-small cell lung carcinomas.

Adult↗

PubMed1995

Genetic disparity between morphologically benign cysts contiguous to ovarian carcinomas and solitary cystadenomas.

BACKGROUND: Ovarian carcinomas occasionally contain large, histologically benign cysts contiguous to the clearly malignant areas (cystadenocarcinomas). The question of whether such cysts are remnants of pre-existing benign tumors (cystadenomas) or constitute integral components of the carcinomas is important in clarifying the role of cystadenomas in ovarian carcinogenesis. It is also important for our general understanding of tumor heterogeneity, a phenomenon thought to result from the gradual accumulation of genetic abnormalities in initially homogeneous tumors. This question is also pertinent to the clinical management of ovarian cystadenomas, which are frequent in women of childbearing age and are usually treated surgically based on the possibility that they may give rise to carcinomas. PURPOSE: Reasoning that molecular markers of ovarian malignancy would be confined to the histologically malignant portions of cystadenocarcinomas if the morphologically benign portions are in fact pre-existing typical cystadenomas, we sought to verify that mutations in the p53 tumor suppressor gene are markers of malignancy in ovarian tumors and to determine the distribution of such mutations in cystadenocarcinomas. METHODS: We used immunohistochemical and DNA-sequencing techniques to analyze 46 ovarian carcinomas, 21 ovarian tumors of low malignant potential, and 16 solitary cystadenomas for the presence of p53 mutations. We then used similar techniques to examine the distribution of such mutations in different portions of cystadenocarcinomas. The observed differences in mutation frequencies were analyzed by the two-tailed Fisher's exact test. RESULTS: Mutations in the p53 gene were present in 24 (52%) of the 46 carcinomas, but they were absent in the 21 tumors of low malignant potential (P < .0001) and the 16 solitary cystadenomas (P = .0002). Six of six cystadenocarcinomas with p53 mutations showed the presence of the same mutations in the adjacent, histologically benign cysts. The mutations were seen not only in cells immediately adjacent to the carcinomas, but also throughout the morphologically benign cysts. Twenty (83%) of the 24 cases showing mutation of one p53 allele also showed loss of genetic heterozygosity, suggesting that the other p53 allele was deleted. Such allelic loss, if present in morphologically malignant portions of cystadenocarcinomas, was also observed in the contiguous cysts. CONCLUSIONS: Ovarian carcinomas can be distinguished from ovarian cystadenomas and tumors of low malignant potential by p53 mutations. The fact that the mutations were present in histologically benign cysts contiguous to ovarian carcinomas suggests that such cysts are not typical cystadenomas and may carry a genetic predisposition to carcinogenesis that is not present in ordinary cystadenomas.

Carcinoma↗