Changes in insulin receptors on methylcholanthrene-induced sarcoma during growth.
Methylcholanthrene-induced sarcomas (MCA-S) have different growth patterns in diabetic (D) and nondiabetic (ND) rats. Diabetes delays the early phase of tumor growth and prolongs survival. This study evaluated MCA-S growth and its relation to insulin receptors (IR) and glucose uptake. Fisher 344 rats 150-200 g were assigned to two groups: Diabetic tumor bearers (DTB, n = 26) and nondiabetic tumor bearers (NDTB, n = 18). Diabetes was induced with iv streptozocin (40 mg/kg); MCA-S was inoculated (1 X 10(6) cells) subcutaneously 10 days later. Animals were sacrificed during early growth (tumor volume less than or equal to 20 cc) or logarithmic growth (tumor volume greater than 20 cc). IR assay was performed (0-10(5) ng/ml cold insulin, 25 X 10(3) cpm/tube A14 125I-insulin, 90 min, 15 degrees C, pH 7.8) on a single cell preparation. Serum glucose milligrams per deciliter and insulin nanograms per milliliter were assayed. Glucose uptake (dpm/g tissue/hr) was assayed 2 hr after an ip injection of 0.5 microCi 3-O[14C]methylglucose. Diabetic, tumor-bearing animals had a significantly increased number of insulin receptors at the small [less than or equal to 20 cc, 28.7 (D) vs 8.3 (ND)] and large [greater than 20 cc, 82.8 (D) vs 27.8 (ND)] tumor volumes. Glucose uptake was increased in the tumor at both volumes in the non-diabetic animals compared to the diabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Division of Oncologic Surgery, City of Hope National Medical Center, Duarte, California 91010.
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LD
Wagman
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Metz
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D008748:Methylcholanthrene / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D011972:Receptor, Insulin / Q000502:physiology*; D012513:Sarcoma, Experimental / Q000378:metabolism / Q000473:pathology*
D001786:Blood Glucose; D007328:Insulin; D008748:Methylcholanthrene; D011972:Receptor, Insulin; D005947:Glucose