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Microsatellite instability in sacral chordoma
L Klingler1, J Shooks, P N Fiedler
1Department of Orthopaedic Surgery, Vanderbilt University, Nashville, Tennessee 37232-2550, USA.
Background And Objectives:
Microsatellite instability (MIN) is an indirect marker of globally defective DNA mismatch repair in the neoplastic cells of cancer patients. Chordomas are rare, primary skeletal malignancies for which few characteristic molecular genetic markers have been identified. Is MIN demonstratable in chordoma?
Methods:
We evaluated sacral chordomas from 12 patients with sacral chordomas for the presence of MIN at 9 different genetic loci from chromosomes 1p, 5q, 7q, 9p, 11p, 12p, 13q, 17p, and 18q. Cells were scraped from glass slides so that tumor and control DNA could be isolated and then amplified by polymerase chain reaction (PCR). Heterozygosity indices were >/= 0.70.
Results:
Six patients (50%) demonstrated MIN for at least 1 locus, and 2 patients demonstrated loss of heterozygosity (LOH) for at least 1 locus. Only 1 individual's chordoma manifested microsatellite instability (MIN) and loss of heterozygosity (LOH). Another patient manifested no MIN but LOH at 9p and 18q. Interestingly, this individual had the most aggressive clinical cancer course, presenting with lymph node metastasis and succumbing to widespread metastatic disease.
Conclusions:
Chordomas can be added to the list of malignancies demonstrating MIN. LOH may prove to portend a worse prognosis than MIN when more tumors are examined.
Insights
Microsatellite instability (MIN) is detectable in chordomas, a rare bone cancer. Loss of heterozygosity (LOH) may indicate a poorer prognosis than MIN in these tumors.
Area of Science:
- Oncology
- Molecular Genetics
- Cancer Research
Background:
- Microsatellite instability (MIN) signifies defective DNA mismatch repair in cancer.
- Chordomas are rare skeletal malignancies with limited known molecular markers.
- The presence of MIN in chordomas remains largely uninvestigated.
Purpose of the Study:
- To determine if microsatellite instability (MIN) is present in human chordomas.
- To investigate the potential association between MIN, loss of heterozygosity (LOH), and clinical outcomes in chordoma patients.
Main Methods:
- Analysis of sacral chordoma samples from 12 patients.
- Evaluation for MIN at 9 genetic loci using polymerase chain reaction (PCR).
- Assessment of loss of heterozygosity (LOH) at various genetic markers.
Main Results:
- Fifty percent of chordoma patients (6/12) exhibited MIN at one or more loci.
- Two patients displayed loss of heterozygosity (LOH).
- One patient with LOH but no MIN showed aggressive disease progression, including metastasis.
Conclusions:
- Chordomas exhibit microsatellite instability (MIN), adding them to the spectrum of MIN-positive malignancies.
- Loss of heterozygosity (LOH) may be a more significant prognostic indicator than MIN in chordomas.
- Further research is warranted to elucidate the prognostic value of LOH in chordoma.
