Sonja Levanat

Elevated levels of substances immunologically cross-reactive with insulin in blood of patients with malignant and nonmalignant pulmonary tissue proliferation.

Results of a survey of concentrations of substances immunologically cross-reactive with insulin (SICRI), glucose and growth hormone in preprandially drawn blood of 84 patients suffering from bronchial epidermoid, microcellular and adenocarcinomas and 22 patients from sarcoidosis, tuberculosis and obstructive bronchitis are presented. In all these diseases, tissue proliferation takes place. Supranormal SICRI concentrations were frequently associated with these diseases, whereas concentrations of glucose and growth hormone remained unaffected; this shows that physiological effects of SICRI in these diseases differ from the effects in patients suffering from some lympho-proliferative and solid tumors. These results indicate that elevated levels of circulating substances detectable by insulin-specific radioimmunoassay can accompany both malignant and nonmalignant proliferation in lungs.

The role of insulin-related substance in Hodgkin's disease

SummaryAn insulin-related growth-promoting substance was detected in the serum of a patient with Hodgkins disease who suffered from severe hypoglycaemia, as well as in the supernatant of homogenized spleen tissue of the same patient. Low concentrations of this substance enhanced DNA synthesis of short-term-cultured spleen tumour cells obtained from the same patient, while the addition of anti-insulin antiserum interfered with that effect. Moreover, the preincubation of this insulin-related substance with the anti-insulin antiserum abrogated its stimulatory effect on tumour cell proliferation. Both insulin and the insulin-related substance bound to patients splenocytes to a similar extent. The data suggest that the insulin-related substance, found in this particular case of Hodgkins disease, plays a role in tumour progression by an autocrine mechanism.

Growth factors in human tumors.

SummaryVarious human tumor tissues contain different growth factors. In some cases progression of tumors is paralleled by elevated levels of these substances in blood or in tumor tissue. There is evidence that these growth promoting peptides might stimulate tumor growth. The growth of most tumors was associated with insulin-like substances (MW 45 000). We isolated and purified a substance immunologically cross-reactive with insulin (SICRI) from human melanoma. We found the molecular weight of affinity purified SICRI to be approximately 120 000. Our in vitro experiments with human renal carcinoma cells and growth factors suggest an important role of these molecules in tumor progression.

Substance Immunologically Cross-Reactive with Insulin (SICRI) Stimulates Cell Division

A substance immunologically cross-reactive with insulin (SICRI) was isolated and purified from murine melanoma B16. Biochemical and biological data provide evidence that SICRI and insulin are two distinct biologically active agents. In vitro, SICRI has stimulated the DNA and protein synthesis, cell growth or colony-forming ability of 19 normal and transformed cell lines of human and rodent origin. It indicates that SICRI is a potent nonspecific growth factor. The most pronounced stimulatory effect of SICRI on proliferative capacity of cells is observed with cells at G0/G1 point of the cell cycle.

PO-149 Expression profiling of TP53, TP73, NME and GLI families of genes/proteins in metastatic melanoma

Introduction Malignant melanoma is the most aggressive form of skin cancer and resistant to available therapies, therefore new molecular approaches for better understanding of disease are needed. Although TP53 is rarely mutated in melanoma, it fails to function as a tumour suppressor. This may result from alterations in p53 family members, including the diverse isoforms of p53 and its homologue p73. Moreover, we assume that p53 functions in melanoma might be altered through interactions with small molecular weight variants of p53 and p73 isoforms, NME and GLI families of proteins. In this study, we conducted a gene/protein expression profiling for p53 and its potential interaction partners (p73/NME/GLI) in metastatic melanoma tissue. Material and methods Metastatic melanoma and adjacent healthy skin tissues were obtained from 38 patients during surgery in the Sestre milosrdnice University Hospital Centre, Zagreb. Expression of 9 TP53 isoforms, both N- (full-length, Δ40 and Δ133) and C-terminal (α, β and γ), 2 TP73 isoforms (TAp73 and ΔNN’p73), NME1, NME2, GLI1, GLI2, GLI3 and PTCH1, was analysed by RT-qPCR. Expression of p53 (p53α, p53β, Δ40p53α, Δ133p53α, Δ133p53β and Δ160p53α isoforms), p73 (TAp53α, TAp53β, ΔNp73α and ΔNp73β), NME1, NME2, GLI1 (130 and 160 kDa isoforms), GLI2 (133 and 250 kDa) and GLI3 (activator/repressor forms) was analysed by western blot. Results and discussions Relative expression of ‘long’ TP53 isoforms in tumour tissue was as follows: p53α>p53β > Δ40α>p53γ > Δ40β > Δ40γ. Expression of ‘short’ TP53 isoforms was: Δ133α > Δ133β > Δ133γ. Only Δ40β and Δ40γ were significantly downregulated in tumours. Expression of full length TAp73 was higher than ΔNp73, and both were significantly downregulated in tumours. Significant downregulation in tumours was also observed for PTCH1, GLI1 and GLI2; while NME1 and NME2 were generally the most expressed genes but without significant difference between healthy and tumour tissue. In addition, in metastatic melanomas the most expressed proteins were p53α and NME1, while ΔNp73β, GLI2 (250 kDa) and Δ133p53α showed lowest expression. Eight proteins showed significantly higher expression in tumours compared with healthy skin: 2 GLI1 isoforms (130 and 160 kDa), 133 kDa GLI2 isoform, NME1 and NME2, ΔNp73Δ and 2 p53 isoforms with shortest N- and longest C-terminus. Conclusion We have shown that TP53/TP73/NME/GLI genes are generally downregulated in metastatic melanoma tissue compared with healthy skin, while, on the contrary, their protein products seem to be upregulated in tumours.

Autocrine tumour growth regulation. modulation of in vitro growth of murine myeloid leukemia by an autologous substance immunochemically cross-reactive with insulin and antiinsulin serum

Murine myeloid leukemia secretes a substance immunochemically cross-reactive with insulin (SICRI) both in vivo and in serum-free media. High SICRI concentrations in peripheral blood of tumorous animals do not affect circulating glucose levels. In culture, DNA synthesis rate per leukemic cell is proportional to cell density and is reduced by antiinsulin serum. Culture medium conditioned by leukemia cells as well as SICRI affinity purified from this medium stimulate DNA synthesis in cultured leukemia cells. It appears that autocrine stimulation of murine myeloid leukemia can be mediated in part by an insulin-related growth factor.

Autocrine tumor growth regulation and tumor-associated hypoglycemia in murine melanoma B16 in vivo

A substance immunochemically cross-reactive with insulin (SICRI) appears in melanoma B16 growing in diabetic and nondiabetic C57BL/6 mice. Progression of tumor size is paralleled by the increase of SICRI levels in the serum of both diabetic and nondiabetic animals; this increase correlates with a decreased concentration of circulating glucose and an elevated concentration of growth hormone in blood. Melanoma B16 grown under serum-free culture conditions secretes SICRI into the medium. Affinity-purified SICRI stimulates glucose uptake by rat epididymal adipocytes and competes with radiolabeled insulin for binding to these cells. Low concentrations of SICRI enhance growth of cultured melanoma B16 cells, whereas high concentrations of this substance have inhibitory growth effects on these cells. Porcine insulin, human insulin-like growth factors I and II, human growth hormone, platelet-derived growth factor, epidermal growth factor, and fibroblast growth factor have negligible influence on growth of melanoma B16.