Evaluation of chromosome 12 copy number in ovarian granulosa cell tumors using interphase cytogenetics

Imbalances of chromosomes 4, 9, and 12 are recurrent in the thecoma-fibroma group of ovarian stromal tumors

Traditional cytogenetic studies of ovarian stromal tumors are few, although trisomy 12 has been frequently documented with fluorescence in situ hybridization (FISH). In the current study, karyotypic analysis of four ovarian stromal tumors and a review of the literature suggest that numerical abnormalities of chromosomes 4 and 9 might also be important, possibly as secondary changes. To determine the frequency of 4, 9, and 12 aneuploidy in a larger group of ovarian tumors, FISH studies were performed on eight fibromas, three thecomas, one fibrothecoma, and five cellular fibromas. Trisomy 12 was identified in all five cellular fibromas as well as in two fibromas and the fibrothecoma. Gain of chromosome 9 was confined to the cellular fibromas. Loss of chromosomes 4 and/or 9 was prominent in the fibromas. These findings confirm the presence of trisomy 12 as a nonrandom chromosomal abnormality in ovarian stromal tumors. Moreover, these conventional and molecular cytogenetic data indicate that gain of chromosome 9 in addition to gain of chromosome 12 is prominent in cellular fibroma. In contrast, loss of chromosomes 4 and/or 9 are recurrent in fibroma. In summary, imbalances of chromosomes 4 and 9 appear to represent important secondary abnormalities in the thecoma-fibroma ovarian tumor group.

Molecular cytogenetics of ovarian granulosa cell tumors by comparative genomic hybridization

OBJECTIVE

Patients with stage I granulosa cell tumors (GCTs) may occasionally develop metastasis, which is hard to predict using pathologic criteria. It is interesting to elucidate whether certain chromosomal imbalances (CIs), detected by comparative genomic hybridization (CGH), could be useful prognostic markers.

METHODS

CGH was used to identify CI(s) in 37 adult-type GCTs from 36 women. Nonrandom CIs were compared with clinical and pathological features to evaluate their significance as a prognostic marker.

RESULTS

Twenty-two (61%) of the 36 primary tumors had CIs. One woman's tumor showed identical CIs to another tumor that occurred in contralateral ovary 2 years later, supporting a metastatic nature. The nonrandom CIs included losses of 22q (31%), 1p33-p36 (6%), 16p13.1 (6%), and 16q (6%) and gains of 14 (25%), 12 (14%), and 7p15-p21 (6%). No tumor exhibited high-level amplification. The associations between each CI and pathological features, including the growth pattern, tumor size, and mitotic activity, were not evident. The only CI repeatedly detected in tumors with metastasis was monosomy 22, which presented in 2 of the 4 cases with metastasis but also in 2 of the 5 cases without recurrence for more than 5 years.

CONCLUSIONS

Monosomy 22 was the most common CI in GCTs, which often coexisted with trisomy 14 (in 55% cases). Deletion of 22q seems to be, albeit not very specific, associated with the risk of early metastases of stage I disease. The role of loss-of-function mutation(s) of certain putative tumor suppressor gene(s) on 22q is worthy of further investigations.

Distal Chr 4 Harbors a Genetic Locus (Gct1) Fundamental for Spontaneous Ovarian Granulosa Cell Tumorigenesis in a Mouse Model

The spontaneous development of juvenile-onset ovarian granulosa cell tumors in mice of the SWXJ-9 recombinant inbred strain is a model for juvenile-type granulosa cell tumors that appear in very young girls. To expedite gene discovery in this mouse model of childhood cancer, we did a gene mapping study with the SWXJ-9 recombinant inbred strain and the evolutionarily divergent Mus musculus castaneus (CAST/Ei) strain as a mapping partner. Our mapping strategy focused on autosomal determinants of susceptibility with a backcross scheme that exploited a paternal, parent-of-origin effect for a X-linked gene (Gct4) that strongly supports granulosa cell tumor development. Of 1,968 backcross females examined, we detected 81 granulosa cell tumor-bearing animals and compared their allelic inheritance patterns to non-tumor-bearing siblings in a case-control analysis. The results of our study have confirmed an important locus on mouse chromosome (Chr) 4 (Gct1) and have revealed new loci for granulosa cell tumor susceptibility (Gct7-Gct9) on Chrs 1, 2, and 13 with susceptibility alleles contributed by the SWXJ-9 progenitor. Two novel gene-gene interactions supportive for granulosa cell tumor development were also observed between loci on Chrs 17 and 18 and loci on Chrs 2 and 10. Our data substantiate the evidence that Gct1 on Chr 4 is a fundamental oncogene for granulosa cell tumorigenesis in mice and has identified additional interacting autosomal loci that support tumor development.

Monosomy 22 as a diagnostic aid in a case of late recurrence of adult granulosa cell tumor of the ovary

Cytogenetic analysis of a case of metastatic granulosa cell tumor recurring 21 years after oophorectomy revealed monosomy 22. This anomaly, typical of granulosa cell tumor, coupled with the pathologic and immunophenotypic findings assisted in establishing the proper diagnosis of this lesion in the absence of the original histopathologic slides.

Granulosa cell tumor of the ovary

Adult granulosa cell tumor (GCT) of the ovary is oftentimes a hormonally active, stromal cell neoplasm that is distinguished by its ability to secrete sex steroids such as estrogen. Patients may present with vaginal bleeding caused by endometrial hyperplasia or uterine cancer as a result of prolonged exposure to tumor-derived estrogen. In addition, GCT is a vascular tumor that may occasionally rupture and result in abdominal pain, hemoperitoneum, and hypotension, mimicking an ectopic pregnancy in younger patients. GCT is usually associated with a mass on pelvic examination that is subsequently confirmed on ultrasonography. Surgery is required for definitive tissue diagnosis, staging, and tumor debulking. In older women, a total abdominal hysterectomy and bilateral salpingooophorectomy are typically performed. In women of childbearing age, a more conservative unilateral salpingo-oophorectomy may be performed, assuming that careful staging reveals that the disease has not extended outside of the involved ovary and that a concomitant uterine cancer has been excluded. Survival of patients with GCT is generally excellent because most patients present with early-stage disease, although certain high-risk patient groups may be identified. Stage is the most important prognostic factor, with a higher risk of relapse being associated with stages II through IV disease. In addition, patients with stage I disease associated with features such as large tumor size, high mitotic index, or tumor rupture may also be at higher risk in some series. The value of postoperative adjuvant therapy for high-risk patients has not been investigated by prospective randomized trials, which are difficult to perform because of the rarity of this tumor. Nonetheless, the use of adjuvant chemotherapy or radiation has sometimes been associated with prolonged disease-free survival in patients with high-risk features. Because of the propensity of GCT to recur years after initial diagnosis, prolonged surveillance with serial physical examination and serum tumor markers such as estradiol and inhibin is reasonable.

FISHing chromosomes in endocrinology

Fluorescencein situ hybridization (FISH) is currently recognized as a reliable, sensitive, and reproducible technique for identification of copy number and structure of chromosomes providing information on the single-cell level. The technique permits cytogenetic investigation of metaphase spreads and interphase nuclei. Several protocols have been used for preparations from fresh samples or archival material. Alphoid or telomeric DNA probes can detect specific chromosomes, and cosmid probes can localize single copies of the segment of interest. FISH is a powerful tool in understanding physiologic mechanisms, in generating high-resolution physical genetic maps, and in resolving problems of the pathogenesis of several diseases. FISH may shed light on the cytogenetic background and chromosomal alterations in the field of endocrinology, resulting in a better understanding of functional activities and various endocrine disorders.