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PubMed1992

Suramin is an inhibitor of DNA topoisomerase II in vitro and in Chinese hamster fibrosarcoma cells.

The antitrypanosomal and antifiliarial drug suramin is currently under investigation for treatment of advanced malignancies including prostatic cancer, adrenocortical cancer, and some lymphomas and sarcomas. Here we show that suramin is a potent inhibitor of the nuclear enzyme DNA topoisomerase II. Suramin inhibited purified yeast topoisomerase II with an IC50 of about 5 microM, as measured by decatenation or relaxation assays. Suramin did not stabilize the covalent DNA-topoisomerase II reaction intermediate ("cleavable complex"), whereas other inhibitors of this enzyme, such as amsacrine, etoposide, and the ellipticines, are known to stabilize the intermediate. In contrast, the presence of suramin strongly inhibited the cleavable-complex formation induced by amsacrine or etoposide. Accumulation of the endogenous cleavable complex was also inhibited. Suramin entered the nucleus of DC-3F Chinese hamster fibrosarcoma cells exposed to radiolabeled suramin for 24 hr as shown by both optic and electron microscopy. The suramin present in the nucleus seemed to interact with topoisomerase II, since suramin reduced the number of amsacrine-induced protein-associated DNA strand breaks in DC-3F cells and protected these cells from the cytotoxic action of amsacrine. Cells resistant to 9-hydroxyellipticine, which have been shown to have an altered topoisomerase II activity, are about 7-fold more resistant to suramin than the sensitive parental cells as shown by 72-hr growth inhibition assay. Our results suggest that DNA topoisomerase II is a target of suramin action and that this action may play a role in the cytotoxic activity of suramin.

Amsacrine↗
PubMed1987

The histologic response of soft tissue sarcoma to radiation therapy.

Twenty-seven patients with soft tissue sarcoma had preoperative radiotherapy, limb-sparing marginal surgical resection and whole-mount tumor histologic analysis. Incisional biopsy specimens before radiotherapy were reviewed for tumor type, grade, and extent of necrosis. Preoperative radiotherapy was given in either of two regimens: 13 patients received a mean total dose of 5250 cGy in one daily 180 to 200 cGy fractions and 14 patients a mean total dose of 4770 cGy in two daily fractions of 180 to 200 cGy separated by 4 hours. Twenty-one specimens had at least 80% necrosis or severely altered cells, a 3+ to 4+ response. Grade and size of the tumor appeared to be indicators of response to treatment rather than histologic type. Three of five patients (60%) with Grade 1, eight of 11 patients (73%) with Grade 2 lesions, and ten of 11 patients (91%) with Grade 3 tumors had 80% or greater necrosis or severely altered cells. For tumors 10 cm or less in greatest diameter, the 3+ to 4+ histologic response was seen in 12 of 14 patients (86%) whereas for lesions greater than 10 cm, this response was observed in nine of 13 patients (69%). For patients with Grade 2 or 3 soft tissue sarcoma, 13 of 14 patients (93%) treated with two fractions per day and two of four patients (50%) receiving one fraction per day exhibited significant response. All six patients treated twice daily for lesions greater than 10 cm had 3+ to 4+ histologic response compared to three of seven (43%) patients treated once per day. Therefore, grade and size of soft tissue sarcoma are important predictors of response to radiotherapy and preoperative twice daily radiotherapy may more likely permit the conservative surgical excision of sarcomas of borderline resectability.

Adolescent↗
PubMed1988

Mode of antitumor action of recombinant human tumor necrosis factor on the sarcoma Meth A transplanted in the mouse.

The mode of antitumor action of rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation with respect to time course, dose-response relationships and selectivity of the effects. The maximal cytotoxic effect on tumor cells revealed by inhibition of DNA synthesis and maximal lesional effect on tumor vasculature revealed by change in blood pool-size in the tissue were detected at 30 min and 1 h after administration of rHu-TNF, respectively. The dose-response relationship between cytotoxic and tumoricidal effects of rHu-TNF was irrespective of administration route. ED50s of these antitumor effects after i.v. administration of rHu-TNF were about 50 times as high as ED50s after i.t. administration. ED50 of i.t. given rHu-TNF for vascular effect was about 20 times as high as that for cytotoxicity while ED50 of i.v. rHu-TNF for vascular effect was only 2-3 times as high as that for cytotoxicity. The whole body autoradiographies with [125I]HSA given i.v. to see the blood influx into tumor tissue and [14C]thymidine given i.v. to see DNA synthesis in the whole body after administration of rHu-TNF revealed that the distribution of radioactivity was markedly changed in the tumor alone without any detectable change in other whole body tissues. In conclusion, the in vivo antitumor effect of rHu-TNF given i.t. or i.v. appears to be exerted through the direct action on Meth A sarcoma rather than indirectly on tumor vasculature. Under present conditions, the effect of rHu-TNF in the whole body tissues seems rather selective on cells and vasculature of the tumor.

Animals↗
PubMed1994

Post-treatment sarcoma in breast cancer patients.

BACKGROUND: Many patients treated for breast cancer with radiotherapy will survive their disease and be at risk for treatment-related sarcoma for many years. METHODS: In order to identify patients with post-treatment sarcoma and define this disease, we examined the records of 99 patients treated for sarcoma with a history of antecedent breast carcinoma. Of these patients, 51 were felt to have a sarcoma unrelated to breast cancer treatment and 48 were felt to have a treatment-related sarcoma (secondary to lymphedema and/or radiation). RESULTS: Lymphangiosarcoma of the extremity was the most common histologic subtype of post-treatment sarcoma, accounting for 22 of 48 cases (46%). Twenty-six patients (54%) developed nonlymphangiosarcoma post-treatment sarcoma; all of these were radiation-associated sarcomas. The median latency interval between the diagnosis of breast cancer and the development of sarcoma was 11 years (range 4-44) and was not different between the two groups. However, patients with nonlymphangiosarcoma were significantly younger when diagnosed with breast cancer than were those with lymphangiosarcoma of the extremity (median 43 vs. 51 years, p < 0.001). The survival of all 48 patients was poor: 5-year survival was 29%. Five-year survival of patients with other types of post-treatment sarcoma was just as poor as those with lymphangiosarcoma of the extremity (30% vs. 28%, p = 0.98). CONCLUSIONS: Patients who develop sarcoma after treatment for breast cancer have a poor prognosis whether it occurs as Stewart-Treves syndrome or other types of post-treatment sarcoma. Younger patients may be at higher risk than are older patients for the development of nonlymphangiosarcoma post-treatment sarcoma.

Adult↗