Study of antiblastomogenic action of epidermal chalones. I. The effect of epidermal chalones on some transplantable mouse tumours.

The effect of chalone-containing ethanol extract of rat skin (CCE) on the growth in mice of transplanted uterine cervix and skin carcinomas, hepatoma-22a, sarcoma-180 and leukemia L-1210 was studied. When CCE is added to the suspension of tumour cells (10 mg CCE/100 mg tumour tissue/ml saline) the most obvious retention of tumour growth is observed on squamous-cell carcinoma of uterine cervix (72.6%; p less than 0.01). The effect of CCE on the growth of other transplanted tumours, including the skin carcinoma, is not significant. As compared to the uterine cervix carcinoma, the skin carcinoma lacked its primary squamous-cell structure during the tumour progression. The possibility of applicative use of chalones for cancer control is discussed.     

Relation between the extent of resection of cutaneous melanomas and the incidence of local recurrence

Under study was the influence of the volume of a dissected primary tumor, the method of plasty of the wound defect and anesthesia upon the incidence of local recidivations of cutaneous melanoma in 1334 patients. Free skin plasty was shown to be necessary in cases of the surgical treatment of cutaneous melanoma excepting localization of the primary tumor on the trunk. Parsimonious excision of the primary tumor and local infiltration anesthesia during operation are thought to be the factors responsible for the development of local recidivation of skin melanomas.     

Toxic effects of certain pentacyclic triterpenoids on early embryogenesis of the sea urchin.

The cytotoxic activity on the developing sea urchin embryos of forty-four pentacyclic triterpenes of plant origin has been studied. Pentacyclic triterpene glycosides from oleanolic acid and hederagenin with free carboxyl groups at C-28 had the highest cytotoxic activity. Triterpenes from meristotropic acid, macedonic acid and lupan did not display cytotoxic effects.     

5-Bromodeoxyuridine-induced carcinogenesis and its modification by persistent estrus syndrome, unilateral nephrectomy, and X-irradiation in rats

We showed earlier that 5-bromodeoxyuridine (BrdUrd), which can substitute for thymidine during DNA synthesis, inducing transition mutations, is incorporated into DNA of various tissues when administered to newborn rats and is not subjected to repair processes. The main purpose of the present experiment is to verify if a direct perturbation of DNA would be sufficient to initiate carcinogenesis. Rats aged 1, 3, 7, and 21 days were given BrdUrd s.c. at a dose of 3.2 mg/animal. At 2 months some of the females were subjected to treatment known to induce persistent estrus; at 1 month a group of males underwent removal of one kidney, and groups of males and females were exposed to a single total-body X-irradiation at a dose of 1.5 Gy (150 rads) per rat. In females, treatment with BrdUrd induced tumors of the ovaries, polyps in the uterus, and tumors of the soft tissues, nervous system, forestomach, glandular stomach, and salivary gland; no such tumor occurred in control females. Induction of persistent estrus increased the incidences of ovarian tumors and of malignant tumors of the uterus. Treatment with BrdUrd also increased the carcinogenic effect of X-rays on the mammary gland. In males, BrdUrd induced tumors of the testis (seminomas) and adenomas of the thyroid gland; solitary tumors of the kidney, nervous system, soft tissues, and bladder were also found. Unilateral nephrectomy reduced the incidences of tumors in the testis and pituitary gland, whereas subsequent treatment with X-rays did not alter the incidences of tumors induced by BrdUrd. These studies demonstrated for the first time that a nucleoside analogue, BrdUrd, has carcinogenic potential. Possible molecular mechanisms for its carcinogenicity and for the effects of the promoting factors are discussed.