Cytogenetic and FISH analysis of endometrial carcinoma

Genomic aberrations in carcinomas of the uterine corpus

Endometrial carcinoma, the most common invasive neoplasm of the female genital tract, occurs either in a hormone-related, less virulent form (type I) or in a hormone-independent, more aggressive form (type II). Another cancer of the uterine corpus is carcinosarcoma, a biphasic or mixed epithelial-mesenchymal tumor, now classified as metaplastic carcinoma. We examined by karyotyping and comparative genomic hybridization a consecutive series of 67 endometrial carcinomas and 15 carcinosarcomas and compared the cytogenetic features of the different carcinoma subtypes. All three subtypes of uterine carcinoma had in common a nonrandom gain of material from 1q and 8q but differed from one another in other respects. Endometrial carcinomas of type I mostly presented gains from chromosome arms 1q and 8q and losses from Xp, 9p, 9q, 17p, 19p, and 19q, whereas endometrial carcinomas of type II showed a more complex imbalance picture, with gains from chromosome arms 1q, 2p, 3q, 5p, 6p, 7p, 8q, 10q, and 20q and losses from Xq, 5q, and 17p. The carcinosarcomas mostly showed gains of or from 1q, 5p, 8q, and 12q but losses from 9q, that is, they were much more similar to endometrial carcinomas in their pattern of acquired genomic changes than to sarcomas of the uterine corpus. It was also possible to identify different copy number changes among the different grades of type I carcinomas, between serous papillary and clear-cell carcinomas of type II, as well as between homologous and heterologous carcinosarcomas. Specifically, type I adenocarcinomas that were highly differentiated mostly showed gains from 1q and 10p; those that were moderately differentiated showed gains from 1q, 7p, 7q, and 10q as well as losses from Xp, 9p, 9q, 17p, 19p, and 19q; whereas those poorly differentiated showed gains from 1q, 2p, 2q, 3q, 6p, 8q, and 20q but losses from Xp, Xq, 5q, 9p, 9q, 17p, and 17q. The serous papillary carcinomas showed gains from 1q, 2p, 2q, 3q, 5p, 6p, 6q, 7p, 8q, 18q, 20p, and 20q but losses from 17p, whereas the clear-cell carcinomas showed gains from 3q, 7p, 8q, 10q, 16p, and 20q but losses from 6q. Finally, the homologous carcinosarcomas presented gains from 1p, 1q, 8q, 12q, and 17q as well as losses from 9q and 13q, whereas the heterologous tumors showed gains from 1q, 8p, and 8q. The reproducibility of the observed correlations between karyotypic aberration patterns and histological differentiation was underscored by the fact that those carcinosarcomas whose epithelial component resembled type I endometrial carcinomas also exhibiting a type I aberration profile, whereas carcinosarcomas with a type II carcinoma differentiation had karyotypic abnormalities similar to those of type II endometrial carcinomas.

Spindle assembly checkpoint defects and chromosomal instability in head and neck squamous cell carcinoma

Alterations in chromosomal number and structure are found in most solid malignancies including head and neck squamous cell carcinoma (HNSC), however, the presence of ongoing, chromosomal instability in HNSC and its relation to spindle assembly checkpoint defects has not been formally demonstrated. We investigated the status of chromosomal instability (CIN) in HNSC primary tumors and cell lines as well as spindle assembly checkpoint integrity in HNSC cell lines. Centromeric fluorescence in situ hybridization (FISH) was carried out on expanded single cell-derived colonies from HNSC cell lines and primary HNSC touch preparations. The deviation of chromosomes from the modal number in single cell derived colonies was 18.4-27% in 6 HNSC cell lines, and 2-3% in a control cell line, HCT116. Twelve primary tumors and 4 normal controls were also studied; all primary tumors demonstrated significant deviation from the modal chromosomal number (average 33.7%, range = 29.9-43.9%), compared to normal controls (average 4.6%, range = 3.6-5.6%). Additional characterization of the rate of chromosomal breakage was carried out by dual color FISH simultaneously using centromeric and telomeric probes for individual chromosomes on expanded singe cell-derived colonies and primary HNSC. Control HCT 116 colonies demonstrated a mean discordance between number of centromeric and telomeric hybridization signals in 21% (range = 19-23%) of cells, whereas HNSC cell line colonies demonstrated a mean discordance of 50% (range = 38-55%), with the majority of instances of discordant signal indicating telomeric loss. Similarly, touch preparations from primary HNSC demonstrated discordance in hybridization signal of centromeric vs. telomeric signal of 26.3% (range = 18.5-42%), with normal controls showing a rate of discordance of 6.4% (range = 4-8%). Finally, all 6 HNSC cell lines demonstrated partial impairment of mitotic arrest in response to nocodazole, indicating that impairment of the spindle assembly checkpoint may contribute to chromosomal instability in HNSC. Ongoing instability in chromosomal number and structure are consistent features of primary HNSC and cell lines. Spindle assembly checkpoint impairment occurs in HNSC cell lines and may contribute to chromosomal instability in HNSC.

Atypical endometrial hyperplasia shares genomic abnormalities with endometrioid carcinoma by comparative genomic hybridization

Endometrial hyperplasia is a common disorder that is now observed with increasing frequency in women treated with hormonal replacement therapy or with tamoxifen. This study was undertaken to determine whether genomic features of various forms of endometrial hyperplasias would allow their classification as a benign, premalignant, or malignant abnormality. Comparative genomic hybridization (CGH) was performed on endometrial glands microdissected by laser capture microscope from 19 archival endometrial samples, comprising 5 normal endometria, 1 polyp, 2 simple hyperplasias, 5 hyperplasias with nuclear abnormalities (atypical hyperplasias), and 4 low-grade and 2 high-grade endometrioid carcinomas, 1 with squamous component (adenoacanthoma). Genomic DNA, extracted from the glands and the squamous component in 1 case, was amplified by degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR) and compared with sex-matched DNA by CGH. No genomic imbalances were observed in the normal samples, the polyp, or the simple hyperplasias. However, in atypical hyperplasia, regardless of the level of cytologic atypia, genomic abnormalities were observed that also occurred in endometrioid carcinomas. Chromosomes 1, 8, and 10 were most often affected. The results are compared with molecular genetic abnormalities recently reported in these lesions. This study strongly suggests that atypical endometrial hyperplasias are closely related to endometrioid carcinoma and should be considered precancerous lesions, contrary to simple hyperplasia, which is a benign disorder. The squamous component of one of the high-grade carcinomas showed genetic abnormalities similar to those of endometrioid carcinoma and therefore does not represent squamous metaplasia but is an integral part of the malignant process.

Fluorescence in situ hybridization in cervical smears: detection of numerical aberrations of chromosomes 7, 3, and X and relationship to HPV infection

BACKGROUND

Human papillomavirus (HPV) is known to play a pivotal role in cervical carcinogenesis. Chromosomal aberrations are known to be related to different biological behaviors of malignant lesions. We analyzed whether numerical chromosomal aberrations, related to more aggressive tumor types, are found not only in high-grade squamous intraepithelial lesions (HSIL) but also in low-grade SIL (LSIL) of the cervix and evaluated their relationship to HPV infection.

METHODS

Eighty women (19 to 74 years of age) were included in this study and grouped according to the Bethesda System: within normal limits (WNL), LSIL, and HSIL. By FISH, chromosomes 7 and X, and in part chromosome 3, were analyzed for numerical aberrations. Using the hybrid capture system HPV detection was performed.

RESULTS

All 20 patients with cervical smear WNL had regular diploid chromosomal pattern and were negative for HPV. Thirteen of the 29 (41.2%) patients with LSIL showed trisomy 7, in association with trisomy X in 4 cases (12.9%). Single trisomy X was detected in 4 cases (12.9%). In 3 of 15 (20%) cases analyzed for chromosome 3 trisomy was observed. Trisomy 3 was associated with trisomy 7 and X or with trisomy 7 alone. The hybrid capture test was performed in 16 patients of this group. Two patients were positive for HPV probe A, 9 for probe B, and 2 for A and B, and 3 patients were negative. Twenty-three of the 29 patients (79.3%) with HSIL showed trisomy 7. Twelve of the 29 patients (41.3%) had an additional trisomy X. Single trisomy X was seen in only 2 cases (6. 9%). Twenty-two patients with HSIL were tested also for chromosome 3. Nine of the 22 patients (40.9%) showed trisomy 3, associated with trisomy 7 or with trisomy 7 and X. In 25 of the 29 patients HPV detection by the hybrid capture system was performed. HPV probe B was positive in 15 cases (60%). One patient was positive for both probes, A and B. Nine (36%) of the patients with HSIL were negative for both HPV probes. No positivity was observed for HPV probe A alone.

CONCLUSION

Our data confirm the pivotal role of HPV in cervical carcinogenesis as it seems to cause changes in the chromosomal pattern of premalignant lesions. Additionally, trisomy 7 may be considered an early event in cervical carcinogenesis, persisting and increasing with progression of the lesion. The roles of trisomy 3 and X need further evaluation.

Numerical abnormalities of chromosomes 1 and 10 in endometrial adenocarcinoma: fluorescence in situ hybridization analysis of 23 archival paraffin-embedded samples

Retrospective analysis of chromosomal changes in endometrial carcinoma was performed by fluorescence in situ hybridization on free nuclei isolated from formalin-fixed paraffin-embedded tissue. We examined 23 archival samples for numerical aberrations of chromosomes 1 and 10 with the use of specific DNA probes for the pericentromeric and centromeric regions of these two chromosomes. Numerical aberrations of chromosomes 1 and 10 were detected in 39% of the case analyzed, and the frequency of trisomy 10 tended to increase as the histological grade worsened. Our findings confirm the association of cytogenetic anomalies involving chromosomes 1 and 10 with endometrial carcinoma, as reported by other studies, and suggest that changes in centromere 10 copy number may correlate with the degree of tumor differentiation.

Detection of DNA gains and losses in primary endometrial carcinomas by comparative genomic hybridization

Comparative genomic hybridization (CGH) was used in a retrospective analysis of chromosomal imbalances in frozen primary tumor specimens from 14 endometrial carcinoma patients. Chromosome changes were detected in nine cases (64%), and tumor stage and grade tended to parallel the degree of genomic imbalances. Gain of the entire long arm of chromosome 1 was observed in six cases (43%), three of which displayed only this chromosome change. Other common sites of copy number increases included 8q21-->qter (4 cases), 10p15 (4 cases), 10q11-->q24 (3 cases), and 13q21-->qter (3 cases, each with stage III disease). Two of the tumors with gains of chromosome 10 involved the whole chromosome, and this was the sole abnormality in one case. DNA amplification at 5p14-->p15 was identified in one specimen, a stage III tumor having numerous imbalances. DNA microsatellite analysis revealed multiple replication errors (RER), indicative of the RER+ phenotype, in four of 13 (31%) cases evaluated. The RER+ phenotype was observed in four of six stage la tumors but in none of seven stage Ib or stage III tumors. Multiple genomic imbalances detected by CGH were not observed in RER+ tumors but were detected in five of nine tumors without the RER+ phenotype. These investigations demonstrate the feasibility of CGH for the retrospective assessment of chromosomal changes in endometrial carcinoma specimens. Moreover, these data suggest that the etiologies in tumors with and without the RER+ phenotype may differ.

Involvement of chromosome 6 in endometrial cancer

Cytogenetic investigation was performed on direct preparations of 15 endometrial cancers showing different histotypes. Clonal abnormalities were found in 11 out of 13 analysable cases. The modal chromosome number was near diploid in all cases. The abnormal karyotypes contained relatively simple numerical or structural aberrations in the majority of tumours. In contrast, two neoplasms with serous papillary and mixed mullerian morphological features shared multiple complex changes as well as cytogenetic evidence of intratumoral heterogeneity. The most frequent chromosome abnormality in our series of endometrial neoplasms was 6q deletion, which was detected in serous papillary, endometrioid and mixed mullerian tumours. The loss of the 6q region, which is also frequently involved in ovarian carcinoma, suggests a relationship between endometrial and ovarian cancers based on a common histogenesis.

Detection of aneuploidy in interphase nuclei from non-small cell lung carcinomas by fluorescence in situ hybridization using chromosome-specific repetitive DNA probes

Interphase fluorescence in situ hybridization (FISH) is particularly useful for detecting chromosome changes in tumors exhibiting a low mitotic index, as is the case in many human non-small cell lung carcinomas (NSCLCs). A panel of centromeric DNA probes specific for the autosomes 6, 7, 8, 9, 12, 17, and 18 was used to analyze 17 primary NSCLCs. Evidence for aneuploidy was obtained in all specimens. Gain of part or all of chromosome 7 was especially prominent, occurring in a large population of cells in each of 14 tumors (82%). Extra centromeric copies of chromosomes 6, 12, and 17 were also common, being observed in 9 to 11 cases each. Gain of chromosome 9 was infrequent (three tumors). In two cases, most of the nuclei had only a single chromosome 9 fluorescent signal. Karyotypic findings were available for six cases and were generally consistent with the FISH data. Both methods revealed considerable heterogeneity within individual tumors. NSCLC specimens from 26 males were assayed with a Y-specific centromeric sequence; loss of the Y was observed in 13 cases (50%). These investigations demonstrate the feasibility of interphase FISH for the successful analysis of numerical chromosome changes in NSCLCs.

Chromosome abnormalities in primary endometrioid ovarian carcinoma

Specific and recurrent chromosome abnormalities may occur in regions of the genome that are involved in the conversion of normal cells to those with tumorigenic potential. Ovarian cancer is the primary cause of death among patients with gynecologic malignancies. We performed cytogenetic analysis in a subgroup of epithelial ovarian tumors, the endometrioid tumors, which are histologically indistinguishable from endometrial carcinoma of the uterus. We studied 10 endometrioid tumors to determine the degree of cytogenetic similarity between these two carcinomas. Six of 10 endometrioid tumors showed a near-triploid modal number, and one had a tetraploid modal number. Eight of the 10 contained structural chromosome abnormalities, of which the most frequent were 1p-- (5 tumors), 6q-- (4 tumors), 19q+ (4 tumors), and chromosome 3 rearrangements (4 tumors). These cytogenetic results resemble those reported for papillary ovarian tumors and differ from those of endometrial carcinoma of the uterus. We conclude that despite the histologic similarities between the endometrioid and endometrial carcinomas, the genetic abnormalities in the genesis of these tumors differ significantly.

Trisomy 7 in keratoacanthoma and squamous cell carcinoma detected by fluorescence in-situ hybridization

Keratoacanthoma (KA) is generally considered to be a clinically and histologically distinct entity, but it often remains difficult to separate from well-differentiated squamous cell carcinoma (WDSCC). Recently, trisomy 7 has been identified in squamous cell carcinoma of the skin. In this study, we examined classical KA (n = 6), WDSCC (n = 7) and squamous cell carcinoma with KA-like features (SCC-KA) (n = 8) for trisomy 7 by fluorescence in-situ hybridization (FISH) to determine if this chromosomal abnormality is unique to squamous lesions diagnosed as WDSCC, or shared by both KA and SCC. In addition, the pertinent clinical-histopathologic findings were summarized. Trisomy 7 was identified in one KA, one SCC-KA and two WDSCC. This study demonstrates that there is a chromosomal abnormality shared by KA and SCC, providing further evidence that KA is most likely a form of SCC. Further studies are required to determine if trisomy 7 in these lesions is of prognostic significance.

Molecular basis of endometrial cancer

BACKGROUND

Most human cancers are thought to arise from alterations in oncogenes and tumor suppressor genes.

METHODS

Molecular techniques have been used to identify specific genetic alterations in endometrial cancers.

RESULTS

Overexpression of the HER-2/neu oncogene occurs in 10% of endometrial cancers and correlates with poor survival. Alterations in other receptor tyrosine kinases (c-fms and epidermal growth factor receptor) also occur in some cases. The c-myc oncogene, which encodes a nuclear transcription factor, also may be overexpressed in some invasive cancers. Mutations in the K-ras oncogene occur in 10% and in 20-30% of American and Japanese endometrial cancers, respectively. K-ras mutations also have been observed in endometrial hyperplasias, and this may represent an early event in the development of some cancers. Mutation of the p53 tumor suppressor gene, with resultant overexpression of mutant p53 protein, occurs in 20% of endometrial adenocarcinomas. Overexpression of p53 is associated with advanced stage and poor survival. Because p53 mutations do not occur frequently in endometrial hyperplasias, this may be a relatively late event in endometrial carcinogenesis. Recent studies have shown that mutations occur in microsatellite sequences in some endometrial cancers. Because microsatellite instability in hereditary nonpolyposis colon cancer has been found to be caused by mutations in DNA repair genes, similar mutations are being sought in endometrial cancers.

CONCLUSIONS

Although several molecular alterations have been identified, the molecular pathogenesis of endometrial cancer remains poorly understood.