Murine C-type RNA virus from spontaneous neoplasms: in vitro host range and oncogenic potential.

Strain BALB/c mice harbor at least two host range variants of marine leukemia virus. One variant, which is host-cell tropic, is the predominant isolate from neoplastic tissues and produced lymphoreticular neoplasms when injected into BALB/c newborn mice. A second variant, whicht is isolated throughout life, grows poorly in host embryonic cells in culture and was not associated with lymphoreticular neoplasm induction when injected into newborn BALB/c mice.

Vasoformative sarcomas arising from BALB/3T3 cells attached to solid substrates.

The BALB/3T3 mouse embryo cell line, noted for its marked postconfluence inhibition of proliferation, anchorage dependence, and high serum requirement, and frequently studied as a prototype nontumorigenic "fibroblast" line that is compared with tumorigenic sublines transformed with various agents, produced tumors within 2 to 3 months when an average of 3 X 10(4) cells were implanted s.c. attached to 1- X 5- X 10-mm polycarbonate platelets. Plastic platelets alone produced no tumors after 1 year of observation. The tumors, as well as others arising from implants of BALB/3T3 cells attached to 3-mm glass beads, were given the histological diagnosis of "vasoformative saroma" because the tumor cells frequently formed vascular channels. The vasoformative pattern and the results of specific staining for reticulin and collagen support the likelihood that BALB/3T3 cells originated from endothelial cells rather than from fibroblasts. That the tumors were derived from BALB/3T3 cells and not host cells was proved when tumors arising in BALB/c X C57BL/6 F1 hybrids were shown to be transplantable to BALB/c but not to C57BL/6 mice. The cultured tumor cells showed loss of both postconfluence inhibition of proliferation and anchorage dependence. Evidence of the induction of endogenous oncornaviruses was obtained in only one of four tumors tested. These tumors also exhibited tumor-unique transplantation rejection antigens. We conclude that BALB/3T3 cells are preneoplastic and give rise to different spontaneously transformed clones bearing unique tumor rejection antigens when implanted in vivo attached to a solid substrate.

[A case of neoplastic angioendotheliosis--possible mechanism of JC virus infection for the selective growth of tumor cells in the blood vessel].

A case of 55-year-old man pathologically proven as neoplastic angioendotheliosis was reported. He initially developed sensory disturbance and motor weakness in the lower extremities. After admission, he showed progressive deterioration of higher brain functions with moderate fever. Routine laboratory examinations revealed elevated serum LDH level and erythrocyte sedimentation rate without leukocytosis or increased serum globulin level. Immunological tests were normal, except positive RA. Immunocytochemical investigation of tumor cells in the blood vessel gave the results that these cells appeared to be derived from B cells. Southern blot analyses of the brain samples revealed clear positive bands corresponding to JC virus DNA in the blot. JC virus has been known to infect the endothelial cells of the blood vessel as well as urethral epithelial cells. We discussed the possible mechanism of the selective growth of tumor cells in the blood vessel in terms of possible JC virus infection to the endothelial cells of the blood vessel and abnormal recognition between tumor cells and endothelial cells.