Identification of p53 mutations by means of single strand conformation polymorphism analysis in gynaecological tumours: comparison with the results of immunohistochemistry

Mutant p53 induces EZH2 expression and promotes epithelial-mesenchymal transition by disrupting p68-Drosha complex assembly and attenuating miR-26a processing

The tumor suppressor p53 and the transcriptional repressor Enhancer of Zeste Homolog 2 (EZH2) have both been implicated in the regulation of epithelial-mesenchymal transition (EMT) and tumor metastasis via their impacts on microRNA expression. Here, we report that mutant p53 (mutp53) promotes EMT in endometrial carcinoma (EC) by disrupting p68-Drosha complex assembly. Overexpression of mutp53 has the opposite effect of wild-type p53 (WTp53), repressing miR-26a expression by reducing pri-miR-26a-1 processing in p53-null EC cells. Re-expression of miR-26a in mutp53 EC cells decreases cell invasion and promotes mesenchymal-epithelial transition (MET). Rescuing miR-26a expression also inhibits EZH2, N-cadherin, Vimentin, and Snail expression and induces E-cadherin expression both in vitro and in vivo. Moreover, patients with higher serum miR-26a levels have a better survival rate. These results suggest that p53 gain-of-function mutations accelerate EC tumor progression and metastasis by interfering with Drosha and p68 binding and pri-miR-26a-1 processing, resulting in reduced miR-26a expression and EZH2 overexpression.

[Mammaglobin in peripheral blood and tumor in breast cancer patients]

Currently, no molecular biological markers do exist for early diagnosis of breast cancer. One of the possible candidates for the marker of early breast cancer is mammaglobin (MGB1) or SCGB2A2 (secretoglobin, family 2A, member 2), characterized by the maximal expression level in early breast cancer. Using the RT-PCR method MGB1 mRNA expression was examined in 57 tumor tissue samples and 57 samples of morphologically non-malignant tissue (MNT) of breast cancer (BC) patients. Specificity and sensitivity of the MGB1 mRNA assay in peripheral blood of BC patients was evaluated by nested PCR. 169 blood samples (from 95 BC patients, 22 from patients with benign breast tumors, 28 from patients with tumors of other localizations, and 24 samples from healthy donors) have been analyzed. MGB1 expression was significantly higher in BC tissue samples compared to MNT (p=0.0019). The maximal expression level was in the samples T1 (p=0.013), stage I BC (p=0.037), GI (p=0.0019). The MGB1 expression positively correlated with expression of estrogen (p = 0,034) and progesterone (p=0.0004) receptors. Sensitivity and specificity of the MGB1 mRNA assay in peripheral blood were 60.6% and 92.3%, respectively. Expression of MGB1 was higher in BC than MNT and it decreased during BC progression. The sensitivity and specificity of the MGB1 mRNA assay may be used as an additional diagnostic method.

Expression of DNA damage response proteins and complete remission after radiotherapy of stage IB-IIA of cervical cancer

The primary aim of this study was to investigate if the expression of the DNA damage identifying protein DNA-PKcs known to be involved in DNA repair after treatment with ionising radiation can be used as a predictive marker for radiotherapy (RT) response in cervical cancer. Formalin-fixed primary tumour biopsies from 109 patients with cervical cancer, FIGO-stage IB–IIA, treated with preoperative brachytherapy followed by radical surgery were analysed by immunohistochemistry. In addition, correlation studies between early pathological tumour response to radiation and expression of Ku86, Ku70, Mdm-2, p53 and p21 in primary tumours were also performed. We found that tumour-transformed tissue shows positive immunostaining of DNA-PKcs, Ku86 and Ku70, while non-neoplastic squamous epithelium and tumour-free cervix glands show negative immunoreactivity. Expression of DNA-PKcs positively correlated with both Ku86 and Ku70, and a statistically significant correlation between the Ku subunits was also found. After RT, 85 patients demonstrated pathologic complete remission (pCR), whereas 24 patients had residual tumour in the surgical specimen (non-pCR). The main finding of our study is that there was no correlation between the outcome of RT and the expression of DNA-PK subunits. Positive p53 tumours were significantly more common among non-pCR cases than in patients with pCR (P=0.031). Expression of p21 and Mdm-2 did not correlate with the outcome of RT.

Positive correlation between the expression of X-chromosome RBM genes (RBMX, RBM3, RBM10) and the proapoptotic Bax gene in human breast cancer

In a recent report, it has been postulated that the ubiquitous RBM proteins might constitute a novel family of apoptosis modulators. We measured the expression of the X-chromosome RBM genes (RBMX, RBM3, and RBM10) in 122 breast cancers by means of differential RT-PCR. Using the same method, we also studied the expression of the apoptosis-related genes Bcl-2 and Bax. Markers of hormone dependence (estrogen and progesterone receptors), proliferation (Ki67 and DNA-ploidy), angiogenesis (VEGF and CD105), as well as oncogene (c-erb-B2), and tumor suppressor gene (p53) expression were also analyzed. The expression of all X-chromosome RBM genes was significantly associated with the expression of the proapoptotic Bax gene (RBMX, P=0.039; RBM3, P<0.001; RBM10 large variant, P<0.001; RBM10 small variant, P<0.001). Furthermore, the expression of both RBM10 variants was significantly associated with the expression of the VEGF gene (large variant, P=0.004; small variant, P=0.003). We also found an association of borderline significance (P=0.05) between the expression of RBM3, the large variant of RBM10 and wild-type p53. Expression of the small RBM10 variant, finally, was associated with high proliferation of the tumors (Ki67>or=20%; P=0.037). The expression of both RBM10 variants seems to be interdependent to a significant degree (r=0.26, P=0.006). From these results, it seems that the X-chromosome, through its RBM genes, plays a formerly unknown role in the regulation of programmed cell death (apoptosis) in breast cancer.

Intratumoral heterogeneous expression of p53 correlates with p53 mutation, Ki-67, and cyclin A expression in endometrioid-type endometrial adenocarcinomas

To further elucidate the significance of p53 mutation in endometrial carcinoma, we investigated it in endometrioid-type endometrial carcinomas showing intratumoral heterogeneous p53 expression. In addition, we also examined the correlation of p53 mutation and cyclin A expression, because we previously reported a topological correlation between the expression of p53 and cyclin A. The p53 mutation in exons 5-8 in 54 cases of endometrial carcinoma showing immunohistochemical expression of p53 was examined using microdissected tissue DNAs. Of the 54 p53-positive endometrial carcinomas, 23 (43%) had p53 mutation with a tendency in histologically higher grade tumors. Ten of the 54 showed a heterogeneous p53 expression, and in 9 of the 10 cases, p53 mutation was present only in p53-positive sites, which were often found in histologically less differentiated areas with elevated Ki-67 in the same tumor. Cyclin A expression was topologically observed in p53-positive areas; however, it was noted in both tumors with (12/23, 52%) and without (18/31, 58%) p53 mutation. These results suggest that p53 mutation is a late event and plays an important role in the acquisition of malignant potentials in endometrioid-type endometrial adenocarcinomas. Unexpectedly, accumulation of the p53 protein itself may be important in cyclin A overexpression.

Elevated mammaglobin (h-MAM) expression in breast cancer is associated with clinical and biological features defining a less aggressive tumour phenotype

BACKGROUND

Mammaglobin (h-MAM) is expressed mainly by breast epithelial cells, and this feature has been used to detect circulating breast cancer cells and occult metastases in sentinel axillary lymph nodes of breast cancer patients. However, the biological role of mammaglobin is completely unknown.

METHODS

We studied 128 fresh-frozen breast cancer specimens by means of reverse transcriptase-polymerase chain reaction and quantified their h-MAM mRNA expression. This was then correlated with histological and nuclear grade, oestrogen and progesterone receptor expression, c-erb-B2 and mutant p53 expression, as well as with cellular proliferation measured by means of the Ki67 labelling index, DNA ploidy and S-phase, and finally with the presence or not of invaded axillary nodes in the mastectomy specimen.

RESULTS

In the univariate analysis, high h-MAM expression (above the median for the whole group) correlated significantly (P < 0.05) with oestrogen and progesterone receptor expression, diploid DNA content, low Ki67 labelling index, low nuclear grade and almost significantly (P = 0.058) with the absence of axillary nodal invasion in the mastectomy specimen. In a final, multivariate model, only progesterone receptor expression, diploid DNA content and absence of nodal invasion were found to be independently associated with high h-MAM expression.

CONCLUSION

All of the features associated with mammaglobin expression reflect, without exception, a less aggressive tumour phenotype. Further studies are needed to clarify whether this is attributable to h-MAM expression itself, or to another mechanism of which mammaglobin expression forms part.

nm23-H1 expression defines a high-risk subpopulation of patients with early-stage epithelial ovarian carcinoma

The role of the nm23 gene in human ovarian cancer is still controversial. We studied the expression of the nm23-H1 gene in 247 human epithelial ovarian carcinomas. The patients were followed-up until their death, or for a minimum of 5 years if they survived. The expression of the gene was studied by means of immunohistochemistry and a semiquantitative scoring system considering the staining intensity and the number of reactive tumour cells. Patients carrying tumours with higher expression scores (4-6 on a scale from 0 to 6) had a significantly lower survival (P = 0.01) than the rest. Further stratified statistical analysis revealed that this effect was mainly attributable to the subgroup of patients with early-stage (I and II), well- and moderately differentiated tumours. In fact, a multivariate analysis carried out for this subset of patients showed nm23-overexpression to be the only significant independent predictor of an ominous prognosis. The association of nm23-overexpression with a worse prognosis was most probably not due to mutation of the nm23 gene, since mutational analysis in 60 tumours by means of single-strand conformational polymorphism and direct sequencing disclosed only one mutation, which was located outside the open reading frame. Our results seem to indicate that nm23 expression is associated with a significantly worse prognosis in early-stage, well-differentiated epithelial ovarian carcinoma, a finding with important clinical implications, considering that many patients with ovarian cancers showing these features do not undergo any further treatment beyond surgical staging. If confirmed, they could help in tailoring the treatment of these patients in the future.

The prognostic significance of p53, mdm2, c-erbB-2, cathepsin D, and thrombocytosis in stage IB cervical cancer treated by primary radical hysterectomy

The objective of this study was to evaluate the value of platelet count, p53, MDM2, c-erbB-2, and cathepsin D immunoreactivity as predictors of lymph node metastasis (LNM) as well as their prognostic significance in patients with stage IB cervical cancer treated by radical hysterectomy between 1991 through 1995. We also report on the outcome of a protocol considering lymph-vascular space invasion (LVSI) in addition to LNM as a strong motivation for adjuvant radiotherapy. A total of 93 patients were the subject of this retrospective study. The incidence of positive nodes was high (30.1%). Thrombocytosis (>/= 400.000/mm3) was present in 6.7% of patients. Positive immunostaining was found for p53 (50.6%), MDM2 (21.7%), c-erbB-2 (14.5%), and cathepsin D (45.8%), but none of them was able to predict LNM. Only thrombocytosis was associated with an unfavorable prognosis: a statistically significant association was shown with relapse-free and overall survival in an univariate analysis (P = 0.0431 and P = 0.0012, respectively) with a tendency to significance in multivariate analysis (P = 0.079 and P = 0.0882, respectively). We postulate that thrombocytosis in early stage cervical cancer could be a marker for subclinical tumor burden. LVSI, regarded as an indication for adjuvant radiotherapy, was no longer associated with poor relapse-free or overall survival, but resulted in a 41% postoperative irradiation rate. Further research is needed to establish the value of LVSI in postoperative radiotherapy decision making.

p53 overexpression and mutation in endometrial carcinoma: inverted relation with estrogen and progesterone receptor status

Overexpression and mutation of p53 in 46 primary endometrial carcinomas were determined comparatively with the status for estrogen receptor (ER) and progesterone receptor (PR). Immunohistochemically p53 overexpression was found in 9 of 46 cases (20%), while eight kinds of mutations in that gene were detected in 7 of 46 endometrial carcinomas (15%), using polymerase chain reaction single-strand conformation polymorphism and subsequently direct sequencing method. Six of nine cases with p53 overexpression showed p53 mutation. All eight mutations showed single substitutions, and three cases in exon 4, one in exon 5, two in exon 6, and two in exon 7 were found. The cases with the p53 overexpression were significantly inversely related to that of ER or PR staining. Most endometrial carcinoma with p53 overexpression and/or mutation had a relatively poor prognosis and showed no reactivities of ER or PR.

Association between nm23-H1 expression, proliferation and apoptosis in non-small cell lung carcinomas

Twelve non-small cell lung carcinomas and adjacent normal lung tissues were examined for mutations of the nm23-H1 gene by using SSCP analysis and for an expression of the nm23-H1 protein by immunohistochemistry. No mutations could be found in either the carcinomas or in the adjacent normal tissues. In contrast, six of 12 carcinomas showed protein expression while only one adjacent normal lung tissue yielded a positive staining result. Therefore, the expression of nm23-H1 protein was analysed in a larger group of non-small cell lung carcinomas (n = 185) to determine whether or not the expression of nm23 protein may be of prognostic relevance. Only a weak relationship between nm23-H1 expression and lymph node involvement was observed. However, a significant correlation between proliferation and nm23-H1 expression was detected. Additionally, a direct correlation between apoptosis and nm23-H1 expression or between myc and nm23-H1 expression was found. Finally, non-small cell lung carcinomas that expressed nm23-H1 protein were more frequently sensitive to doxorubicin than carcinomas that did not express this protein.

Loss of heterozygosity of BRCA1, TP53 and TCRD markers analysed in sporadic endometrial cancer

Genetic alterations of tumour suppressor genes, for which loss of heterozygosity (LOH) is one mechanism of gene inactivation, are important steps in the development of endometrial cancer. To investigate the clinical relevance of LOH of BRCA1 (17q21), TP53 (17p13) and TCRD (14q11) in endometrial cancer, polymerase chain reaction (PCR)-based fluorescent DNA technology for the detection of microsatellite polymorphisms was applied. One hundred and thirteen archival endometrial cancer samples with matched normal tissues were examined. Allele loss at three loci were correlated with age, tumour size, lymph node status, metastases, stage, histological types, grade, expression of oestrogen receptor (ER) and progesterone receptor (PgR), family history of cancer, previous history of cancer or precursor lesions, and previous history of hormone replacement therapy (HRT). LOH for BRCA1 was detected in 18.1%, of TP53 in 26.9%, and of TCRD in 26.3% of informative cases. LOH of BRCA1 correlated with medium grade, positive ER status, and family history of cancer; LOH of TP53 correlated with younger age, high grade, positive PgR status, and with tumours from patients without HRT; LOH of TCRD correlated only with family history of cancer. LOH at all three loci correlated only with grade and positive family history. Allele loss of one of the three tumour suppressor loci did not correlate with disease-free survival (DFS), but LOH of BRCA1 correlated significantly with decreased overall survival (OS). The latter, together with the correlation of LOH of BRCA1 locus with steroid hormone receptor expression, might give a hint to the potential involvement of the co-localised 17 beta-hydroxysteroid dehydrogenase (HSD) gene in the development of endometrial cancer.

p53, vessel count, and vascular endothelial growth factor expression in human colon cancer

We previously demonstrated an association between vascular endothelial growth factor (VEGF), vessel counts and metastasis in human colon cancer specimens. Mutant p53 has been implicated in the regulation of angiogenesis. Immuno-histochemical detection of p53 protein has been associated with p53 gene mutations. We sought to determine a correlation between p53 protein detection (i.e., mutant p53), VEGF expression and vessel counts in human colon cancer. Surgical specimens from 93 patients with colon cancer were stained immuno-histochemically for p53, VEGF and factor VIII. Vessel counts were greater in metastatic tumors than in nonmetastatic tumors and adenomas, and greater in nonmetastatic tumors than in adenomas. Vessel counts were highest in tumors with the highest VEGF expression. Vessel counts and VEGF expression were greater in p53-positive tumors than in p53-negative tumors. p53 expression correlated with both VEGF expression and vessel count. The association of p53 expression with VEGF and vessel count suggests that the poor prognosis associated with p53 mutations may be due, in part, to the role of mutant p53 in promoting angiogenesis.

Loss of heterozygosity for defined regions on chromosomes 3, 11 and 17 in carcinomas of the uterine cervix

Loss of heterozygosity (LOH) frequently occurs in squamous cell carcinomas of the uterine cervix and indicates the probable sites of tumour-suppressor genes that play a role in the development of this tumour. To define the localization of these tumour-suppressor genes, we studied loss of heterozygosity in 64 invasive cervical carcinomas (stage IB and IIA) using the polymerase chain reaction with 24 primers for polymorphic repeats of known chromosomal localization. Chromosomes 3, 11, 13, 16 and 17, in particular, were studied. LOH was frequently found on chromosome 11, in particular at 11q22 (46%) and 11q23.3 (43%). LOH on chromosome 11p was not frequent. On chromosome 17p13.3, a marker (D17S513) distal to p53 showed 38% LOH, whereas p53 itself showed only 20% LOH. On the short arm of chromosome 3, LOH was frequently found (41%) at 3p21.1. The beta-catenin gene is located in this chromosomal region. Therefore, expression of beta-catenin protein was studied in 39 cases using immunohistochemistry. Staining of beta-catenin at the plasma membrane of tumour cells was present in 38 cases and completely absent in only one case. The tumour-suppressor gene on chromosome 3p21.1 may be beta-catenin in this one case, but (an)other tumour-suppressor gene(s) must also be present in this region. For the other chromosomes studied, 13q (BRCA-2) and 16q (E-cadherin), only sporadic losses (< 15% of cases) were found. Expression of E-cadherin was found in all of 37 cases but in six cases the staining was very weak. No correlation was found between clinical and histological parameters and losses on chromosome 3p, 11q and 17p. In addition to LOH, microsatellite instability was found in one tumour for almost all loci and in eight tumours for one to three loci. In conclusion, we have identified three loci with frequent LOH, which may harbour new tumour-suppressor genes, and found microsatellite instability in 14% of cervical carcinomas.

The impact of tumour angiogenesis, p53 overexpression and proliferative activity (MIB-1) on survival in squamous cervical carcinoma

Tumour angiogenesis (antifactor VIII-related antigen antibody), p53 overexpression (DO-1) and proliferative activity (MIB-1) were immunohistochemically analysed for the prediction of long-term survival in 113 patients with squamous cervical carcinoma. The median follow-up time was 82 months (range 72-99). In early stages (IB-IIA), neovascularisation was significantly related to tumour size. Significantly more patients in stage IIA had high tumour vascularity compared to stage IB (P < 0.01) but no significant difference was found between early and advanced stages (IIB-IVB) of cervical carcinoma. p53 overexpression was correlated to the stage of disease (P < 0.01). No relationship was found between tumour angiogenesis, p53 overexpression or MIB-1 and pelvic lymph node metastases, histological subtype or differentiation. Tumours with more than 50% p53 overexpression was significantly correlated with survival in the univariate analysis, but no independent predictive value was found. It is concluded that immunohistochemically detectable p53 overexpression as measured by DO-1 and proliferative activity as measured by MIB-1 seems of no clinical value for the prediction of long-term survival in squamous cervical carcinoma. The predictive value of tumour angiogenesis for survival outcome has still to be determined in squamous cervical carcinoma.

Mutational analysis of the p16 gene in human neuroblastomas

Neuroblastoma is one of the most frequent tumors in infancy. We analyzed 26 neuroblastomas, two ganglioneuromas, and a neuroblastoma metastasis for mutations and homozygous deletions of the p16 (or MTS1 or CDKN2) gene by means of the polymerase chain reaction (PCR) in combination with the single-strand conformation polymorphism (SSCP) technique and by multiplex PCR analysis. We detected mobility shifts in the SSCP gels in seven cases in the 3 half of exon 2 (named exon 2C) of the p16 gene. By PCR amplification of this particular region and SacII restriction enzyme digestion, we confirmed that those cases had a known polymorphism at codon 140 of the p16 gene. Neither mutations nor homozygous deletions were detected. Our results confirm those of Beltinger et al. (Cancer Res 55:2053-2055, 1995), which showed no p16 mutations or homozygous deletions in 18 primary neuroblastomas and nine tumor-derived cell lines. We conclude that the common pattern of p16 inactivation by homozygous deletion or mutation does not seem to be relevant to the development of neuroblastomas.

Expression and mutational analysis of P53 in stage IB and IIA cervical cancers

OBJECTIVE

This study evaluates overexpression of the p53 protein and point mutation in the P53 gene in a group of patients with stage IB and IIA cervical cancer.

STUDY DESIGN

We reviewed the medical records of all patients who underwent radical hysterectomy for the treatment of stage IB and IIA cervical cancer between 1980 and 1985 at Memorial Sloan-Kettering Cancer Center. Overexpression of p53 protein was determined with the use of immunohistochemistry on fixed and paraffin-embedded tissue. Two blocks were selected for each tumor, and tissue sections from each block were tested with both monoclonal (Ab-6) and polyclonal (CM-1) anti-p53 antibodies. Molecular analysis for determination of specific P53 gene mutations was performed with single-strand conformation polymorphism analysis. A group of 132 patients was identified for inclusion in the study.

RESULTS

Fifty-eight of 132 tumors (44%) showed overexpression of the p53 protein and were subjected to molecular analysis. Discrepancy between pairs of blocks (7/132, 5.3%) and between antibodies for the same block (5/264, 1.9%) was uncommon. High-level overexpression was rare (5/132, 3.8%). No difference in survival was found on the basis of overexpression of p53 protein. Only one of the 58 cases (1/58, 1.7%) that showed overexpression of the p53 protein exhibited a point mutation (exon 8) in P53 by single-strand conformation polymorphism. This case had a low level of overexpression of p53 protein on immunohistochemistry.

CONCLUSIONS

Low levels of overexpression of p53 were frequently seen in early cervical cancers (40/132, 30%). However, mutation of the P53 gene was rarely seen in these tumors. Overexpression of p53 protein as detected by immunohistochemistry is not predictive of a somatic mutation in the P53 gene in cervical cancer. Molecular analysis is required for confirmation of P53 mutations in these tumors.

Large core biopsy for diagnostic and prognostic evaluation of invasive breast carcinomas

Large core biopsy is a recently introduced method for pre-operative evaluation of breast lumps. The aim of this study was to evaluate the usefulness of this technique in providing pre-operative diagnostic and prognostic information that can lead to a correct line of treatment. We compared 41 cases of breast carcinomas diagnosed both by core biopsies and surgically removed samples. A high (93%) diagnostic agreement was obtained. Moreover, we found a significant correlation for mitotic count (r = 0.76), oestrogen receptor (r = 0.78), progesterone receptor (r = 0.80), p53 (r = 0.86) and c-erbB-2 (r = 0.90) analysis between core biopsy and definitive surgical pathology. An agreement for histological grading evaluation between the two techniques was obtained in 32 out of 40 cases (k = 0.65) whereas in the other cases, a lower grade was assigned by evaluating core biopsies. These findings suggest that percutaneous core breast biopsy is a valid tool for pre-operative management of breast lesions, but this should be confirmed in larger, prospective studies.

Overexpression of p53 protein is an independent prognostic indicator in human endometrial carcinoma

The important role of the p53 gene in tumour progression and cellular response to DNA damage has prompted investigation of the clinical significance of alterations to this gene. We examined both p53 overexpression and mutation of the gene in endometrial carcinoma in order to evaluate the prognostic significance of these changes. Of 122 endometrial carcinomas, 33 (27%) showed overexpression of p53 in the nucleus and 66 (54%) in the cytoplasm. Mutation in the p53 gene was found in 16 (13%) cases but showed no significant association with patient survival. Nuclear p53 overexpression was associated with poor survival (48% vs 80% alive in negative tumours 5 years post operatively, P < 0.001). In contrast, cytoplasmic p53 overexpression was associated with better survival (85% vs 55%, P < 0.001). When patients were separated into prognostic subgroups according to established clinical markers, these associations remained significant within most subgroups examined. In multivariate analysis adjusted for surgical stage, histological grade and type and vascular invasion, both nuclear p53 overexpression [hazard ratio 4.9 (95% CI 1.3-17.6). P = 0.016] and cytoplasmic overexpression [0.25 (0.06-0.98), P = 0.047] were independent prognostic factors. Immunohistochemical assessment of p53 overexpression in the nucleus and cytoplasm could provide useful prognostic information for the management of patients with endometrial cancer.

Prognostic value of immunohistochemically detected p53 expression in vulvar carcinoma

BACKGROUND

Overexpression of the p53 protein has been reported to correlate with poor prognosis in several types of tumors. To the authors' knowledge, there are no studies concerning the prognostic value of p53 protein overexpression in squamous cell vulvar carcinoma.

METHODS

Twenty-five cases of squamous cell carcinoma of the vulva with International Federation of Gynecology and Obstetrics (FIGO) Stage I-II were examined for p53 protein overexpression using immunohistochemistry. The correlation of p53 protein overexpression with clinical stage, histologic grade, and overall survival was investigated. Follow-up ranged from 36 to 120 months.

RESULTS

Clinical stage and histologic grade did not correlate with p53 protein overexpression. p53 protein overexpression was associated with poorer overall survival (log rank: P < 0.05).

CONCLUSION

Immunohistochemically detected p53 protein overexpression is significantly correlated with a reduced overall survival rate for patients with vulvar carcinoma.

Detection of TP53 gene mutations in human sarcomas

To determine the frequency and type of TP53 mutations in human sarcomas, we examined exons 5-8 of the TP53 gene in 48 sarcomas using single-strand conformation polymorphism (SSCP) analysis and direct sequencing. Nine tumours had mobility-shifts on SSCP analysis, and sequencing of six of these tumours revealed 10 mutations: one insertion, two deletions and seven point mutations (four transitions and three transversions). Four of these mutations resulted in frame-shifts, one in a truncated protein, four cases in mono-allelic point mutations and one case in an altered splice site. These data show that approximately 20% of sarcomas harbour TP53 gene alterations and illustrate a variety of TP53 gene mutation types.