Takanori Kawaguchi

Brain surface invasion and metastasis of murine malignant melanoma variants

Mouse B16 melanoma sublines were selected sequentially for their abilities to colonize brain meninges and leptomeninges of C5713L/6 mice. After 14 selections subline 1316-B14b was established that formed significantly more brain tumor colonies than the parental B16 line. Examination of brains at various times after intravenous or intra-arterial injection of B16 cells by electron microscopy revealed that B14b melanoma cells lodged in small brain blood vessels, proliferated and invaded through vessel walls into brain parenchyma and also along small blood vessels at perivascular sites. Invasion into brain parenchyma was characterized by extension of melanoma cell filopodia resulting in fragmentation and sometimes enfulgment of glial and neural cells.Analysis of cell surface proteins of B16 melanoma sublines revealed increased exposure of a Mr ∼ 90 000 glycoprotein on the high brain-colonizing cells. Antibodies against the Mr ∼ 90 000 glycoprotein reacted with a variety of human melanoma cell lines and with some fetal and adult tissues, indicating that this melanoma-associated component is not species-, tumor- or tissue-specific. The glycoprotein could be a cell surface receptor important in the survival and growth properties of melanoma cells in brain microenvironments.

Reduction of leaky lymphocyte clones producing immunoglobulins and thymic lymphocytic leukemia by selective inbreeding of SCID (severe combined immunodeficiency) mice.

Selective inbreeding of C.B17-scid/scid mouse pairs showing undetectable IgG and IgM has been carried out in order to reduce the mortality of mice by early occurrence of thymic lymphocytic leukemia and abnormal lymphocyte clones producing immunoglobulins, both of which inhibit the successful heterotransplantation of normal and neoplastic human tissues. Although the majority of C.B17-scid/scid mice showed undetectable (< 1 microgram/ml) or low level (< or = 25 micrograms/ml) of serum IgG and IgM, some produced abnormally high concentrations of IgG and IgM (> 25 micrograms/ml). The incidence of such mice showing higher levels of IgG was very high at F1 and F2 generation (10/55, 18.2%), but significantly low after the F3 generation (18/446, 4.0%, p << 0.001). Although leukemia incidence was very high at F4 to F5 generations (8/40, 20.0%), death from leukemia was not observed early in life (4-6 months after birth) at F7 to F10 generations (0/36, 0%, p < 0.01) and was very low during the age of 6-10 months after the F8 generation (11/66, 16.7% at F4 and F5 vs 4/93, 4.3% at F8-10), p < 0.01). Scid mice improved by the selective inbreeding will provide an invaluable experimental system for the heterotransplantation of normal and neoplastic human tissues.

Differential tumor growth of blood-borne B16 melanoma variants in cerebral dura mater is related to tumor-host cell reactions.

Intracarotid injection of B16-B14b or B16-B15b melanoma cells, previously established from B16-F1 melanoma byin vivo selection fourteen- or fifteentimes, respectively, for brain surface colonization, preferentially produced tumor nodules in mice at brain surface sites, most frequently in the dura mater, followed by the leptomeninges and cerebral cortex. There was a marked difference, however, in tumor growth at these sites using the two B16 sublines. Intracarotid injection of B16-B14b cells rarely produced visible tumors, whereas B16-B15b cells formed deeply pigmented tumors up to 7 mm in diameter in the brain meninges of almost all mice examined. Histologic and electron microscopic investigation revealed that B16-B14b tumors evoked dramatic immunocyte cell infiltration and granulomatous reactions, while B16-B15b tumors were accompanied by much less tumor-host cell reactions. Splenectomy or laparotomy 1–2 weeks before or after intracarotid injection of B16-B14b cells dramatically enhanced tumor growth in the dura mater without extensive tumor-host cell reactions. The results suggest that the differential growth of B16-B14b and B16-B15b tumor cells in the cerebral dura mater is based, in part, on the abilities of these melanoma cells to elicit host cell reactions.

Recurrence of cancer in the heterotopically auto-transplanted caudal pancreas

We performed segmental auto-transplantation of the caudal pancreas to the groin after total pancreatectomy and sufficiently preserved the endocrine functions of the pancreas in 20 patients with advanced pancreatic head cancer. Nineteen patients have died, and autopsies were permitted for 18 of these 19 patients. The autopsies were performed 49–922 (mean 404) days after surgery. Cancer cells were microscopically noted in the transplanted pancreas in 2 of 2 patients in whom cancer cells had been noted on the transected plane of the pancreas in the postoperative examination. Cancer cells were also noted in the transplanted pancreas in 10 of 16 patients whose transected plane had been free of cancer cells in the postoperative examination. In the surviving patient, the transplanted pancreas was removed 39 months after surgery, due to recurrence. Thus, the recurrence rate was 11/17 (64.7%). The site of recurrence was the proximal portion of the graft in 10 of these 11 patients. It is suggested that there were some precursor cells left in the transected portion of the transplanted pancreas which subsequently developed into cancer cells.

Giant Polypoid Cancer of the Gallbladder

A 76-year-old Japanese woman underwent en bloc resection of the gallbladder, inferior portion of the medial lobe of the liver and regional lymph nodes for a giant polypoid cancer of the gallbladder. T