Analysis of Ki-ras, p53, and MDM2 genes in uterine leiomyomas and leiomyosarcomas

Transition from squamous cell carcinoma to adenocarcinoma in adenosquamous carcinoma of the lung

The heterogeneity of tumor cells is frequently observed in lung cancer, but the clonality of these cells has not yet been established. The distinct components of 12 lung adenosquamous carcinomas were compared by genetic alterations of p53 and K-ras, chromosomal abnormalities at 9p21 and 9q31-32, and immunohistochemical reactions. The immunoreactivity of p53 was consistent in both adenocarcinomatous and squamous cell carcinomatous components as well as in the transitional areas, retaining the morphological characteristics of the distinct components. The same p53 mutation was found in both components of each tumor with p53 overexpression. No K-ras mutations were detected in any of the tumors examined. Three of the four tumors with chromosomal abnormalities detected, one at 9p21 and two at 9q31-32, had coincident abnormalities between the distinct components, whereas one tumor deleted homozygously at 9p21 (D9S259) in the adenocarcinomatous component with loss of heterozygosity in the other component. The expression of squamous cell carcinoma-related antigen in adenocarcinomatous components was significantly higher than that of lung adenocarcinomas (57 +/- 5.8% vs. 1.0 +/- 0.5%, P < 0.0001), whereas Mucin 1 expression is less in these components (9.0 +/- 4.9% vs. 55 +/- 8.2%, P = 0.003). These results suggest monoclonal transition from squamous cell carcinoma to adenocarcinoma in lung adenosquamous carcinoma.

Uterine smooth muscle tumors: utility of classification by proliferation, ploidy, and prognostic markers versus traditional histopathology

CONTEXT

Accurate categorization of uterine smooth muscle neoplasms by light microscopic examination is difficult. Multiple classification schemes have been proposed based on mitotic rate, nuclear atypia, and the presence or absence of necrosis. None of these classification systems has been entirely successful. Multiple ancillary techniques have been tested for their ability to predict behavior of uterine smooth muscle tumors.

OBJECTIVE

We assayed 45 smooth muscle neoplasms for a variety of proliferation markers, oncogene protein products, and DNA ploidy level to determine if these markers supplied prognostically useful information over and above that obtained by routine light microscopic assessment.

STUDY DESIGN

Forty-five uterine smooth muscle neoplasms were assessed for DNA ploidy; silver-staining nucleolar organizer regions (AgNORs); percent nuclear proliferating cell nuclear antigen (PCNA); expression of p53, Her-2/neu, and MDM-2 protein; mitotic rate; and nuclear grade. These markers were correlated with histologic diagnosis and the occurrence of a clinically adverse event (death, metastasis, or recurrence).

RESULTS

Diagnostic category (P <.001), nuclear grade (P <.002), mitotic activity (P <.001), mean AgNORs (P <.001), percent nuclear PCNA (P =.02), and expression of p53 (P =.02) all correlated with clinical outcome. No statistically significant correlation between clinical outcome and the categories MDM-2 expression, Her-2/neu expression, or DNA ploidy was seen. Nuclear grade, p53 expression, mitotic rate, AgNORs, and percent nuclear PCNA correlated with diagnosis.

CONCLUSIONS

Diagnostic category, mitotic rate, AgNOR counts, PCNA, and p53 expression dichotomized uterine smooth muscle neoplasms into prognostically favorable and unfavorable groups. Although highly significant, the category AgNORs was no more successful than mitotic rate in dividing uterine smooth muscle neoplasms into prognostically favorable and unfavorable groups. Expression of p53 and percent nuclear PCNA dichotomized uterine smooth muscle neoplasms into prognostic groups, but neither technique reached the level of significance achieved by mitotic rate. Our data indicate that mitotic rate and the classification system of Kempson and Bari are at least as effective as the tested markers in separating uterine smooth muscle neoplasms into prognostic categories.

Protein expression and genetic alterations of p53 and ras in intrahepatic cholangiocarcinoma

AIMS

The significance of molecular and genetic alterations of p53 and ras in the development and progression as well as the histological differentiation of intrahepatic cholangiocarcinoma (ICC) was evaluated.

METHODS AND RESULTS

We examined immunohistochemically ras p21 protein and p53-related products (p53 protein, WAF-1 and mdm-2) in 43 cases of ICC. In addition, point mutations of ras and p53 were examined genetically in selected ICC cases by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequence analysis. Point mutation of K-ras gene codon 12 was detected in three of 14 cases and one of 15 cases by PCR-RFLP and direct sequence analysis, respectively. Immunoreactivity of ras p21 protein was not detected. Point mutation of p53 was detected in three of 15 cases. p53 protein was immunohistochemically detectable in 33 of 43 cases. Immunoreactivity of p53 was more frequent in well-differentiated and less frequent in poorly differentiated cases. Immunoreactivity of WAF-1 and mdm-2 was seen in 16 and eight of 43 cases, respectively. Both proteins were frequently detected in the cases positive for p53 protein.

CONCLUSION

These results suggest that dysregulation of ras is involved in at least 20% of ICC and expression of p53 protein is more significantly involved in ICC, particularly in the well and moderately differentiated cases. While some cases of p53 expression may be explainable by point mutation of p53, there may be some epigenetic phenomena that stabilize p53 protein in ICC. That is, wild type p53 may be stabilized and then detectable by forming complexes with other molecules of p53 downstream effector genes, such as WAF-1 and mdm-2.

Human pancreatic leiomyosarcoma (PZX-7) growing as a serially transplantable xenograft in immunosuppressed mice

BACKGROUND

Several human leiomyosarcoma xenografts have been established, but pancreatic smooth muscle sarcomas have never been serially transplanted and investigated.

METHOD

Immunosuppression of CBA/CA mice was achieved by thymectomy, whole-body irradiation, and bone marrow reconstruction. Tumor fragments were subcutaneously implanted from a Grade III pancreatic leiomyosarcoma and serially passaged for more than 24 mo. The xenografted tumors were characterized by morphological, morphometrical, biochemical, and flow cytometric methods.

RESULTS

The tumor has retained its characteristic morphology and no further differentiation occurred. The mitotic counts and the amount of the connective tissue all remained constant. The calculated volume doubling time was 11.3 d. Immunohistochemically, the tumor proved to be p53-negative, but the strong expression of the bcl-2 remained as a constant feature throughout successive transplantations. The DNA index and the proliferation indices did not change significantly with the time (mean DI: 1.65, range: 1.561-1.70; mean PI: 17.9%, range: 15.3-20.7%). Lactose dehydrogenase (LDH) isoenzyme electrophoresis evidenced a retained human pattern of the tumor even after 32 mo of transplantations.

CONCLUSION

The first human pancreatic leiomyosarcoma xenograft (PZX-7) growing in immuno-suppressed mice is described and characterized.

TP53 alterations in relation to the cell cycle-associated proteins p21, cyclin D1, CDK4, RB, MDM2, and EGFR in cancers of the uterine corpus

In the present study, TP53 alterations have been analysed and compared with the expression of the proteins p21, cyclin D1, cdk4, RB, EGFR, and MDM2 in 53 cancers of the uterine corpus. TP53 gene mutations analysed by CDGE/DGGE and direct sequencing showed a TP53 gene mutation in 18 per cent of the cases. TP53 gene mutations were not significantly related to overexpression or down-regulation of any of the proteins. Immunohistochemically, there was an increased protein level of TP53 in 77 per cent, p21 in 36 per cent, cyclin D1 in 45 per cent, cdk4 in 77 per cent, EGFR in 8 per cent, and MDM2 in 32 per cent of the cases. Expression of RB protein was normal in all cancers. Significant association of protein expression was seen between TP53 and MDM2 (p=0.005) and p21 and MDM2 (p=0.001). Furthermore, there may be an association between TP53 and p21 (p=0. 038) and cyclin D1 and cdk4 (p=0.045). The results revealed increased levels of TP53 protein in all MDM2-positive cases that did not show TP53 mutations, indicating TP53 protein stabilization and inactivation by complex formation with MDM2. In summary, the high number of cases showing an increased level of TP53 and cdk4 proteins suggests that these proteins play an important role in the neoplastic process in cancers of the uterine corpus.

DNA copy number changes in development and progression in leiomyosarcomas of soft tissues

DNA copy number changes were investigated in 29 leiomyosarcomas by comparative genomic hybridization. The most frequent losses were detected in 10q (20 cases, 69%) and 13q (17 cases, 59%). The most frequent gains were detected in 17p (16 cases, 55%). The most frequent high-level amplifications were detected in 17p (7 cases, 24%) and 8q (6 cases, 21%). A total of 137 losses and 204 gains were detected. Small tumors (less than 5 cm in diameter) displayed fewer changes per sample (3 to 11; mean, 7) than the other tumors (4 to 22; mean, 13). There was an increase in the number of gains from small tumors (mean, 4) to very large tumors (>20 cm; mean, 10). However, the number of losses was similar in small, large, and very large tumors (mean, 4.5). Tumor size-related aberrations were observed. Gains in 16p were detected in all small tumors but were infrequent in large and very large tumors (27% and 11%, respectively). Similarly, gains and high-level amplifications in 17p were more common in small (80%) than in very large tumors (33%). Gains in 1q, 5p, 6q, and 8q were not seen in any of the small tumors but were detected in large and very large tumors. Gains in 6q and 8q occurred in 8 of 9 cases (89%) of very large tumors, 5 of them with a high-level amplification in 8q.