Yoshito Ueyama

Expression of the multidrug resistance-associated protein (MRP) gene in non-small-cell lung cancer.

We examined the levels of expression of the multidrug resistance-associated protein (MRP) gene quantified by Northern blot analysis in comparison with those of the MDR1 gene determined by reverse transcription-polymerase chain reaction (RT-PCR) in 104 non-small-cell lung cancer (NSCLC) specimens [59 adenocarcinoma (Ad), 40 squamous cell carcinoma (Sq), four large cell carcinoma (La) and one adeno-squamous carcinoma (AdSq)]. Thirty-three (31.7%) of the 104 NSCLC expressed the MRP gene at various levels. The NSCLC showing high (++) levels of MRP gene expression (19 out of 33, 57.6%) were predominantly squamous cell carcinomas (Ad, 5; Sq, 13; La, 1) (P < 0.05). Six of the eight NSCLCs expressing high levels of MRP mRNA and no MDR1 (MRP ++, MDR1-) were squamous cell carcinomas. Sixty-one of the 104 NSCLC patients received chemotherapy with MRP-related anti-cancer drugs [vindesine (VDS) and etoposide (VP-16)]. Twenty-three patients (37.7%) with tumour expressing high or moderate levels of MRP showed significantly worse prognoses than those with non- or low-MRP-expressing tumours (P < 0.05). These results suggest that the level of MRP gene expression is related to the histopathology and prognosis of NSCLC.

Ultrastructural localization of P-glycoprotein on capillary endothelial cells in human gliomas.

The P-glycoprotein (P-Gp) encoded by the human multidrug-resistance gene MDR1 has been suggested to play certain roles in the blood-brain barrier (BBB). However, the detailed mechanism of the activity of P-Gp in multidrug-resistance (MDR) remains unclear in human glioma. We examined the localization of P-Gp in human glioma by immunohistochemical (IHC) and immunoelectron microscopic (IEM) methods with anti P-Gp monoclonal antibodies (C219, MRK16). We also examined MDR1 expression in primary glioma and xenografts by reverse transcription-polymerase chain reaction (RT-PCR) with human MDR1-specific primers. The IHC study showed no P-Gp expression on tumour cells but it was present on capillary endothelial cells and IEM analysis showed definitive localization on their luminal surface. MDR1 gene expression was detected in eight primary glioma and three normal brain specimens by RT-PCR, but not in glioma xenografts. The lack of MDR1 expression in these cells appears to be a consequence of the replacement of the original human stroma, including blood vessels, by murine stroma in glioma xenografts. The unique distribution of P-Gp on the capillary blood vessels was confirmed in human glioma by the results of immunohistochemical and molecular biological studies.

Murine P-glycoprotein on stromal vessels mediates multidrug resistance in intracerebral human glioma xenografts.

Human glioma usually shows intrinsic multidrug resistance because of the blood-brain barrier (BBB), in which membrane-associated P-glycoprotein (P-gp), encoded by the human multidrug resistance gene MDR1, plays a role. We studied drug sensitivity to vincristine (VCR), doxorubicin (DOX) and nimustine (ACNU) in both intracerebrally and subcutaneously xenotransplanted human glioma. We examined the levels of MDR1 and murine mdr3 gene expression in the xenografts by reverse transcriptase polymerase chain reaction and the localization of P-gp by immunohistochemistry. Six of seven subcutaneously transplanted xenografts (scX) were sensitive to the above three drugs. In contrast, all three intracerebrally transplanted human glioma xenografts (icX) were resistant to P-gp-mediated drugs VCR and DOX, but were sensitive to the non-P-gp-mediated drug ACNU. Neither icX nor scX showed any MDR1 expression. Intracerebrally transplanted human glioma xenografts showed an increased level of murine mdr3 gene expression, whereas scX showed only faint expression. The localization of P-gp was limited to the stromal vessels in icX by immunohistochemistry, whereas scX expressed no P-gp. Our findings suggest that the P-gp expressed on the stromal vessels in icX is a major contributing factor to multidrug resistance in human glioma in vivo.

Expression of the Multidrug Resistance Gene (MDR1) in Non-small Cell Lung Cancer

To examine the clinical relevance of P‐glycoprotein, encoded by the human multidrug resistance gene (MDR1), to multidrug resistance in lung cancer, we examined the expression of MDR1 in 107 non‐small cell lung cancer (NSCLC) specimens and 20 corresponding specimens of normal lung tissues. We also evaluated the relationship between MDR1 expression and the histopathology and pathological staging of NSCLC. The tumors consisted of 60 adenocarcinomas, 38 squamous cell carcinomas, 8 large cell carcinomas, and 1 adenosquamous carcinoma. MDR1 expression was semi‐quantified by use of the reverse transcriptase‐polymerase chain reaction method. We subclassified the NSCLC into 3 grades according to the MDR1 expression level (‐, +, ++). Sixty‐one of the 107 tumor specimens (57%) and 18 of the normal lung tissue specimens (90%) expressed various levels of the MDR1 gene. Only one tumor specimen showed higher MDR1 expression than the corresponding normal lung tissue. The relationship between pathological stage and MDR1 expression levels was not significant. These results suggest that the level of MDR1 expression in lung cells is decreased as cells progress from the normal to the transformed state.

Autonomous production of granulocyte-colony stimulating factor in tumour xenografts associated with leukocytosis

Leukocytosis sometimes accompanies malignant neoplasms in the absence of infection. It is thought that the production of colony-stimulating factor by neoplasms is the most potent cause of tumour-induced leukocytosis; several mechanisms have been suggested to explain this. We examined 155 human tumour xenografts established in nude mice, and found that 17 of the xenografts induced remarkable leukocytosis (> 15,000 microliters-1) in nude rats. We examined granulocyte colony-stimulating factor (G-CSF) production by the xenografts to study the mechanisms underlying this tumour-induced leukocytosis. Ten of the 17 xenografted human tumours appeared to express the G-CSF gene. Serum G-CSF increased, to concentrations of 179-37,218 pg ml-1, in host animals transplanted with the ten xenografts expressing the G-CSF gene transcripts. The biological activity of serum G-CSF also increased, to concentrations of 206-9,074 pg ml-1, in the host animals transplanted with the ten xenografts. Immunohistochemical analysis demonstrated G-CSF production at the cellular level in three of the ten xenografts. These results suggested that the production of G-CSF is a common event in human tumour xenografts associated with leukocytosis, but that factors other than G-CSF are also likely to be involved. Leukocytosis induced by neoplasms seems to be a heterogeneous and complex disorder.

A xenograft line of human teratocarcinoma established by serial transplantation in severe combined immunodeficient (SCID) mice

We established a xenograft line of human teratocarcinoma (TC‐1) and characterized the pluripotency of differentiation of the neoplastic cells. A teratocarcinoma specimen obtained from a primary mediastinal lesion (22‐year‐old male patient) was inoculated subcutaneously into severe combined immunodeficient (SCID) mice. The carcinoma formed tumors in the mice. We established a xenograft line by serial passage of the tumor in vivo. The primary tumor was composed of papillary and pseudoglandular nests of highly atypical epithelial cells with foci of glomeruloid structures. The metastatic cells showed apparent production of mucin and differentiation to striated muscle. The xenograft line TC‐1 retained the basic histopathological features seen in the primary and metastatic cells. The xenograft line showed focal differentiation to cartilage through serial passages. Immunohistochemical studies with anti‐α‐fetoprotein (AFP) demonstrated positive immunoreactivity on the TC‐1 cells. Serum AFP levels were also elevated in the TC‐1‐bearing SCID mice. The human teratocarcinoma xenograft line TC‐1 will be useful for studying the differentiation mechanism in human totipotent stem cells.