Molecular pathogenesis in granulosa cell tumor is not only due to somatic FOXL2 mutation

Serum vascular endothelial growth factor associated with the progression of granulosa cell tumor: a report of two cases

BACKGROUND

Granulosa cell tumors (GCTs) account for approximately 2% of ovarian malignancies and are considered a rare type of ovarian cancer. GCTs are characterized by irregular genital bleeding after menopause due to female hormone production as well as late recurrence around 5-10 years after initial treatment. In this study, we investigated two cases of GCTs to find a biomarker that can be used to evaluate the treatment and predict recurrence.

CASE PRESENTATION

Case 1 was a 56-year-old woman who presented to our hospital with abdominal pain and distention. An abdominal tumor was found, and GCTs were diagnosed. Serum vascular endothelial growth factor (VEGF) levels decreased after surgery. Case 2 involved a 51-year-old woman with refractory GCTs. Carboplatin-paclitaxel combination therapy and bevacizumab were administered after the tumor resection. After chemotherapy, a decline in VEGF levels was observed, but serum VEGF levels increased again with disease progression.

CONCLUSIONS

VEGF expression may be of clinical importance in GCTs as a clinical biomarker for disease progression, which may be used to determine the efficacy of bevacizumab against GCTs.

PMS2 gene mutation results in DNA mismatch repair system failure in a case of adult granulosa cell tumor

Background

Granulosa cell tumors are rare ovarian malignancies. Their characteristics include unpredictable indolent growth with malignant potential and late recurrence. Approximately 95% are of adult type. Recent molecular studies have characterized the FOXL2 402C > G mutation in adult granulosa cell tumor. Our previous case report showed that unique FOXL2 402C > G mutation and defective DNA mismatch repair system are associated with the development of adult granulosa cell tumor.

Findings

In this study, the DNA sequences of four genes, MSH2, MLH1, MSH6, and PMS2, in the DNA mismatch repair system were determined via direct sequencing to elucidate the exact mechanism for the development of this granulosa cell tumor. The results showed that two missense germline mutations, T485K and N775L, inactivate the PMS2 gene.

Conclusions

The results of this case study indicated that although FOXL2 402C > G mutation determines the development of granulosa cell tumor, PMS2 mutation may be the initial driver of carcinogenesis. Immunohistochemistry-based tumor testing for mismatch repair gene expression may be necessary for granulosa cell tumors to determine their malignant potential or if they are part of Lynch syndrome.