Tamoxifen, a non-steroidal anti-estrogen widely used against breast cancer, is also useful for treatment of other malignancies, due to its sensitizing effect on other chemotherapeutic agents and radiation. We have investigated the advantages of combining tamoxifen with one of the commonly used cancer chemotherapeutic drug, etoposide (VP-16) in brain tumor cell lines. While tamoxifen (10 microM) increased etoposide cytotoxicity 8.3-fold in the human glioma cell line (HTB-14), it increased etoposide cytotoxicity 47.5- and 40-fold in two primary cell lines established from pediatric medulloblastoma patients (MCH-BT-31 and MCH-BT-39), respectively. Similarly, in the pediatric ependymoma cell lines (MCH-BT-30 and MCH-BT-52), tamoxifen enhanced etoposide cytotoxicity 6- and 2.68-fold, respectively. CalcuSyn analysis of cytotoxicity data showed that tamoxifen and etoposide combinations were synergistic with combination index values ranging from 0.243 to 0.369 at IC50 level among different pediatric brain tumor cell lines. Tamoxifen is also cytotoxic at higher concentrations (> 20 microM) in brain tumor cells. To understand the mechanism underlying the tamoxifen modulation of etoposide cytotoxicity, we analyzed expression of P-glycoprotein (P-gp), insulin-like growth factor-I receptor (IGF-IR), IGF-I, IGF-II and estrogen receptor as well as protein kinase C (PKC) activity. While P-gp, IGF-IR and IGF-I were not affected, enhanced inhibition of PKC, and IGF-II were observed in brain tumor cells treated with tamoxifen and etoposide combination as compared to cells treated with either drug alone. Tamoxifen at 10 microM when combined with etoposide at 0-100 microM concentrations reduced PKC activity 77% compared to only 58% without tamoxifen. IGF-II expression decreased to 48.6% of the untreated control in the combination treatment as compared to 31.2% for etoposide alone and 26.2% for tamoxifen alone treatments. These results suggest that inhibitory effect of tamoxifen on brain tumor cells manifest through different mechanisms involving inhibition of targets such as PKC and IGF-II.
A child with acute pre-B cell lymphoblastic leukemia underwent haploidentical bone marrow transplantation (BMT) after first relapse. Approximately 8 months after the BMT, he developed a soft tissue mass overlying a defect in the left frontal bone. He was found to have several additional osteolytic lesions but no evidence of lymphadenopathy or organomegaly. A biopsy of the presenting lesion demonstrated a polymorphous infiltrate composed predominantly of S-100 protein and CD68 immunoreactive histiocytic cells. Together with the presence of emperipolesis, the process was interpreted as Rosai-Dorfman (R-D) disease. He received chemotherapy with vinblastine, prednisone, 6-mercaptopurine and methotrexate and has been in remission for over 4 years. Only one previous example of acute lymphoblastic leukemia in childhood has been reported with R-D disease.
Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome characterized by neonatal hypoglycemia, abdominal wall defects, macroglossia, organomegaly, ear pits and creases, hemihypertrophy, and increased birthweight. Children with BWS have an increased risk of malignancy. The authors present the case of a 3-year-old boy diagnosed with both BWS and acute lymphocytic leukemia (ALL). This case report will elaborate on the possibilities as to how BWS and ALL may be associated due to abnormal genomic imprinting and IGF dysregulation.
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