[Antitumor effect of S-1 and cisplatin treatment against human gastric cancer xenografted in nude mice]

The enhanced effects due to the combined use of oral administration of S-1 and intraperitoneal administration of Cisplatin (CDDP) were examined with gastric cancer xenografts (NUGC 4). S-1, a new anticancer drug, was daily administered at 10 mg/kg (qld x 5 x 3 weeks). 5-FU level in blood was 1 microgram/ml at two hours after the treatment. Antitumor activity was not found in mice with only the CDDP treatment. But antitumor activity by S-1 and daily low-dose (1 mg/kg) or intermittent treatment (5 mg/kg) of CDDP showed better results than daily S-1 treatment. The daily low-dose CDDP treatment showed similar efficacy to the intermittent administration at the same total dose, but the daily low-dose CDDP treatment was better in the light of toxicities. These results suggest that treatment with S-1 and daily low-dose CDDP was effective for gastric cancer.

Correlation between thymidine phosphorylase expression and prognosis in human renal cell carcinoma

PURPOSE

Thymidine phosphorylase (TP) is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and has angiogenic activity. We examined whether TP expression in renal cell carcinoma (RCC) is associated with microvessel density as a marker of angiogenesis, clinicopathologic characteristics, and outcome.

PATIENTS AND METHODS

The enzymatic activity and expression of TP were examined in 18 RCCs and 19 kidney tissues not grossly involved with tumor from 24 patients with 13 paired samples and 11 unpaired samples by spectrophotometry and immunoblotting. The relationship between TP expression and microvessel density was assessed by immunohistochemistry in 133 RCCs.

RESULTS

The median enzymatic activity of TP in RCCs was nine fold higher than that in nonneoplastic kidney tissues (P < .001). Similar results were obtained by immunoblot analysis. According to the TP staining profile, tumors were classified as no or low, intermediate, or high TP-expressing tumors. TP positivity was significantly correlated with microvessel density. TP expression was correlated with tumor grade, but there was no significant association between TP expression and other clinicopathologic characteristics. TP expression as a prognostic variable was studied using Cox's proportional hazards model. TP overexpression was an independent prognostic factor (hazards ratio, 3.95; 95% confidence interval, 0.98 to 15.89; P = .039) as were nodal category, metastases category, tumor grade, and venous invasion.

CONCLUSION

These findings suggest that TP expression is correlated with microvessel density in RCC and is an unfavorable independent prognostic factor. The future development and characterization of TP inhibitors may provide a novel approach to the therapy of RCC.

Altered mRNA expression of specific molecular species of fucosyl- and sialyl-transferases in human colorectal cancer tissues

Human colorectal cancers express various cancer-associated carbohydrate determinants such as Lewis Y or sialyl Lewis A, suggesting a considerable alteration in glycosyltransferase activities occurring upon malignant transformation. We investigated the mRNA amounts of fucosyltransferase (Fuc-T) and sialyltransferase (ST) isoenzymes, including Fuc-T III, IV, V, VI and VII and ST-3N, ST-30 and ST-4, in human colorectal cancer tissues by Northern blotting and RT-PCR. Regarding fucosyltransferases, mRNA of Fuc-T III and VI was not significantly altered, and only Fuc-T IV mRNA showed a moderate increase in cancer tissues when compared with adjacent non-malignant colonic epithelia taken from the same patient (273 +/- 96%; p < 0.001). The moderate increase of Fuc-T IV message may be related to an enhanced expression of Lewis Y in colon cancer tissues. In the ST isoenzymes, mRNA for ST-3N remained unchanged, whereas that for ST-4 decreased significantly in cancer tissues, to 32 +/- 29%, (p < 0.005). The most remarkable finding was that the message of ST-30 was prominently increased in cancer tissues compared with non-malignant colorectal mucosa. When further investigated by quantitative RT-PCR assays on a larger series of patients with colorectal cancers, the average increase in mRNA for ST-30 was 459 +/- 200% compared with that in adjacent non-malignant epithelium (significant at p < 0.0001). The increase of ST-30 message was more prominent in the cancer tissues strongly expressing sialyl Lewis A than in the cancer tissues expressing sialyl Lewis A only weakly or moderately (significant at p < 0.05). The marked increase in the message of ST-30 is suggested to be related to an enhanced expression of sialylated carbohydrate determinants in colon cancer tissues including sialyl Lewis A, since the enzyme exhibited a significant activity against the type 1 chain carbohydrate substrate and produced the precursors for sialyl Lewis A synthesis, when its cDNA was expressed in Cos-7 cells.

Altered mRNA expression of specific molecular species of fucosyl- and sialyl-transferases in human colorectal cancer tissues

Human colorectal cancers express various cancer-associated carbohydrate determinants such as Lewis Y or sialyl Lewis A, suggesting a considerable alteration in glycosyltransferase activities occurring upon malignant transformation. We investigated the mRNA amounts of fucosyltransferase (Fuc-T) and sialyltransferase (ST) isoenzymes, including Fuc-T III, IV, V, VI and VII and ST-3N, ST-30 and ST-4, in human colorectal cancer tissues by Northern blotting and RT-PCR. Regarding fucosyltransferases, mRNA of Fuc-T III and VI was not significantly altered, and only Fuc-T IV mRNA showed a moderate increase in cancer tissues when compared with adjacent non-malignant colonic epithelia taken from the same patient (273 +/- 96%; p < 0.001). The moderate increase of Fuc-T IV message may be related to an enhanced expression of Lewis Y in colon cancer tissues. In the ST isoenzymes, mRNA for ST-3N remained unchanged, whereas that for ST-4 decreased significantly in cancer tissues, to 32 +/- 29%, (p < 0.005). The most remarkable finding was that the message of ST-30 was prominently increased in cancer tissues compared with non-malignant colorectal mucosa. When further investigated by quantitative RT-PCR assays on a larger series of patients with colorectal cancers, the average increase in mRNA for ST-30 was 459 +/- 200% compared with that in adjacent non-malignant epithelium (significant at p < 0.0001). The increase of ST-30 message was more prominent in the cancer tissues strongly expressing sialyl Lewis A than in the cancer tissues expressing sialyl Lewis A only weakly or moderately (significant at p < 0.05). The marked increase in the message of ST-30 is suggested to be related to an enhanced expression of sialylated carbohydrate determinants in colon cancer tissues including sialyl Lewis A, since the enzyme exhibited a significant activity against the type 1 chain carbohydrate substrate and produced the precursors for sialyl Lewis A synthesis, when its cDNA was expressed in Cos-7 cells.

Function of P-glycoprotein expressed in placenta and mole

We examined the expression of P-glycoprotein in human placentas and hydatidiform moles. Trophoblasts in all the examined placentas and moles expressed P-glycoprotein, and the size of the P-glycoprotein was smaller than that in multidrug-resistant human epidermoid carcinoma KB cells. The P-glycoprotein in the placenta and mole was photolabeled with [3H]azidopine, and [3H]vincristine was transported in an ATP-dependent manner into membrane vesicles prepared from trophoblasts that expressed P-glycoprotein. These findings indicate that P-glycoprotein expressed in trophoblasts has a drug binding site(s) and the ability to transport vincristine, suggesting that P-glycoprotein in the placenta protects the fetus from xenobiotics and confers drug resistance on moles.

Altered mRNA expression of specific molecular species of fucosyl- and sialyl-transferases in human colorectal cancer tissues

Human colorectal cancers express various cancer-associated carbohydrate determinants such as Lewis Y or sialyl Lewis A, suggesting a considerable alteration in glycosyltransferase activities occurring upon malignant transformation. We investigated the mRNA amounts of fucosyltransferase (Fuc-T) and sialyltransferase (ST) isoenzymes, including Fuc-T III, IV, V, VI and VII and ST-3N, ST-30 and ST-4, in human colorectal cancer tissues by Northern blotting and RT-PCR. Regarding fucosyltransferases, mRNA of Fuc-T III and VI was not significantly altered, and only Fuc-T IV mRNA showed a moderate increase in cancer tissues when compared with adjacent non-malignant colonic epithelia taken from the same patient (273 +/- 96%; p < 0.001). The moderate increase of Fuc-T IV message may be related to an enhanced expression of Lewis Y in colon cancer tissues. In the ST isoenzymes, mRNA for ST-3N remained unchanged, whereas that for ST-4 decreased significantly in cancer tissues, to 32 +/- 29%, (p < 0.005). The most remarkable finding was that the message of ST-30 was prominently increased in cancer tissues compared with non-malignant colorectal mucosa. When further investigated by quantitative RT-PCR assays on a larger series of patients with colorectal cancers, the average increase in mRNA for ST-30 was 459 +/- 200% compared with that in adjacent non-malignant epithelium (significant at p < 0.0001). The increase of ST-30 message was more prominent in the cancer tissues strongly expressing sialyl Lewis A than in the cancer tissues expressing sialyl Lewis A only weakly or moderately (significant at p < 0.05). The marked increase in the message of ST-30 is suggested to be related to an enhanced expression of sialylated carbohydrate determinants in colon cancer tissues including sialyl Lewis A, since the enzyme exhibited a significant activity against the type 1 chain carbohydrate substrate and produced the precursors for sialyl Lewis A synthesis, when its cDNA was expressed in Cos-7 cells.

Imaging of recurrent intestinal carcinoma with indium-111-labeled anti-carcinoembryonic antigen monoclonal antibody CEA102

CEA102 is a mouse immunoglobulin G1 monoclonal antibody (mAb) that detects an epitope of carcinoembryonic antigen (CEA). The biodistribution and imaging characteristics of indium-111-labeled (111-In)-mAb CEA102 were studied in 1 primary and 9 extrahepatic recurrent intestinal carcinoma patients. Evaluation included antibody pharmacokinetics and assessment of antibody distribution in surgical specimens, in comparison with whole body imaging using a gamma camera, and imaging with single photon emission computed tomography. Selective mAb CEA102 localization to tumor tissue was demonstrated in 7 patients with tumors over 2 cm in size, and the external images correlated well with the results of surgical inspection, pathological examination, and tissue radioactivity measurements. Tumor:serum ratios ranged from 0.20:1 to 3.22:1, and serial biodistribution study of "regions of interest" also demonstrated a high radioactivity in the tumor. These results indicated the potential exploitability of the 111-In-labeled mAb CEA102 in radioimmunodetection of primary and extrahepatic recurrence of CEA-positive intestinal carcinomas.

Altered mRNA expression of specific molecular species of fucosyl- and sialyl-transferases in human colorectal cancer tissues

Human colorectal cancers express various cancer-associated carbohydrate determinants such as Lewis Y or sialyl Lewis A, suggesting a considerable alteration in glycosyltransferase activities occurring upon malignant transformation. We investigated the mRNA amounts of fucosyltransferase (Fuc-T) and sialyltransferase (ST) isoenzymes, including Fuc-T III, IV, V, VI and VII and ST-3N, ST-30 and ST-4, in human colorectal cancer tissues by Northern blotting and RT-PCR. Regarding fucosyltransferases, mRNA of Fuc-T III and VI was not significantly altered, and only Fuc-T IV mRNA showed a moderate increase in cancer tissues when compared with adjacent non-malignant colonic epithelia taken from the same patient (273 +/- 96%; p < 0.001). The moderate increase of Fuc-T IV message may be related to an enhanced expression of Lewis Y in colon cancer tissues. In the ST isoenzymes, mRNA for ST-3N remained unchanged, whereas that for ST-4 decreased significantly in cancer tissues, to 32 +/- 29%, (p < 0.005). The most remarkable finding was that the message of ST-30 was prominently increased in cancer tissues compared with non-malignant colorectal mucosa. When further investigated by quantitative RT-PCR assays on a larger series of patients with colorectal cancers, the average increase in mRNA for ST-30 was 459 +/- 200% compared with that in adjacent non-malignant epithelium (significant at p < 0.0001). The increase of ST-30 message was more prominent in the cancer tissues strongly expressing sialyl Lewis A than in the cancer tissues expressing sialyl Lewis A only weakly or moderately (significant at p < 0.05). The marked increase in the message of ST-30 is suggested to be related to an enhanced expression of sialylated carbohydrate determinants in colon cancer tissues including sialyl Lewis A, since the enzyme exhibited a significant activity against the type 1 chain carbohydrate substrate and produced the precursors for sialyl Lewis A synthesis, when its cDNA was expressed in Cos-7 cells.

[ATP-dependent glutathione conjugate export pump]

KCP4 cells are resistant to cisplatin and have a GS-X pump different from MRP. The GS-X pump was suggested to be involved in reducing the accumulation of cisplatin in KCP-4 cells. The expression of cMOAT was 4-to 6-fold higher in KCP-4 cells and two other cisplatin-resistant human cell lines. It is still not clear whether the cisplatin resistance in KCP-4 cells are attributed to cMOAT. Other members of the MRP/GS-X pump family have been reported. Amino acid sequence of EBCR of rabbit is 91% identical to that of human cMOAT. On the view of cancer chemotherapy, it is very important to understand the structure and function of GS-X pumps since they may be involved in not only drug resistance but also drug metabolism and side effects.

Treatment of human cancers by NO-releasing reagents related to Mn-SOD

Nitric oxide (NO) plays various roles in organisms, including its anti-tumor effect. But it was not well known how NO actually influences human cancer cells and destroys them. We investigated the relation between NO and SODs using S-nitroso-N-acetyl penicillamine (SNAP), an NO releasing reagent. In several cancer cells treated with SNAP, the expression of manganese-superoxide dismutase (Mn-SOD) mRNA and the enzymatic activity of Mn-SOD were both enhanced. These results suggest that some human cancers which are resistant to NO may enhance the expression of Mn-SOD in order to protect themselves against NO radicals. Such mechanism is also expected to offer a clue to the practical use of NO donors as an anti-cancer drug.

Alternative splicing of the FHIT gene in colorectal cancers

In the present study, we examined the status of the FHIT gene in 112 colorectal cancer and 137 colorectal adenoma specimens. In a total of 5 specimens (4 colorectal cancers and 1 colorectal adenoma), a common smaller product was detected in addition to the normal size product. This smaller product had lost exon 4, the 5' noncoding region of the FHIT gene, owing to alternative splicing. Moreover, all of the 5 tumors with alternative splicing were located lower on the rectum than the anterior peritoneal reflection.

Adhesion molecules and TGF-beta1 are involved in the peritoneal dissemination of NUGC-4 human gastric cancer cells

Peritoneal dissemination frequently occurs after surgery in patients with gastric cancer. The presence of peritoneal metastasis after surgery affects prognosis. Very little is known about the biochemical processes involved in the initial attachment of gastric cancer cells to peritoneal mesothelial cells. We conducted in vitro and in vivo studies to assess the role of adhesion molecules and TGF-beta1 in this process, using 4 cell lines derived from human gastric cancers. NUGC-4 cells, which disseminate early after inoculation into the abdominal cavity of nude mice, predominantly express CD44H and beta1 integrin. We found that NUGC-4 cells adhered to monolayers of mesothelial cells more firmly than to other cell lines. Adhesion of NUGC-4 cells to mesothelial cells was partially inhibited by antibodies against CD44H or the beta1 subunit of integrin and was completely blocked by a combination of these 2 antibodies. Treatment with ligands for CD44H and beta1 integrin also inhibited adhesion. In the NUGC-4 cell culture medium, larger amounts of TGF-beta1 were detected in relation to the increase in cancer cells than in the other cell lines. TGF-beta1 increased the expression of CD44H in NUGC-4 cells and in mesothelial cells and augmented adhesion and implantation of NUGC-4 cells to mesothelial cells accompanied by accumulation of extracellular matrix (ECM) components. Treatment with antibodies against both CD44H and beta1 integrin inhibited the dissemination of NUGC-4 cells in the peritoneal cavity of nude mice and prolonged their survival time. Our findings suggest that CD44H and integrins mediate the initial attachment of gastric cancer cells to mesothelial cells and that TGF-beta1 participates in the promotion of the disease. Increased expression of CD44H and of the amount of ligands for CD44H and integrins induced by TGF-beta1 promotes early development of peritoneal dissemination.

Adhesion molecules and TGF-beta1 are involved in the peritoneal dissemination of NUGC-4 human gastric cancer cells

Peritoneal dissemination frequently occurs after surgery in patients with gastric cancer. The presence of peritoneal metastasis after surgery affects prognosis. Very little is known about the biochemical processes involved in the initial attachment of gastric cancer cells to peritoneal mesothelial cells. We conducted in vitro and in vivo studies to assess the role of adhesion molecules and TGF-beta1 in this process, using 4 cell lines derived from human gastric cancers. NUGC-4 cells, which disseminate early after inoculation into the abdominal cavity of nude mice, predominantly express CD44H and beta1 integrin. We found that NUGC-4 cells adhered to monolayers of mesothelial cells more firmly than to other cell lines. Adhesion of NUGC-4 cells to mesothelial cells was partially inhibited by antibodies against CD44H or the beta1 subunit of integrin and was completely blocked by a combination of these 2 antibodies. Treatment with ligands for CD44H and beta1 integrin also inhibited adhesion. In the NUGC-4 cell culture medium, larger amounts of TGF-beta1 were detected in relation to the increase in cancer cells than in the other cell lines. TGF-beta1 increased the expression of CD44H in NUGC-4 cells and in mesothelial cells and augmented adhesion and implantation of NUGC-4 cells to mesothelial cells accompanied by accumulation of extracellular matrix (ECM) components. Treatment with antibodies against both CD44H and beta1 integrin inhibited the dissemination of NUGC-4 cells in the peritoneal cavity of nude mice and prolonged their survival time. Our findings suggest that CD44H and integrins mediate the initial attachment of gastric cancer cells to mesothelial cells and that TGF-beta1 participates in the promotion of the disease. Increased expression of CD44H and of the amount of ligands for CD44H and integrins induced by TGF-beta1 promotes early development of peritoneal dissemination.

[Effects of carcinostatic agents in the hematogenous metastasis of cancer]

The experimental studies in vitro and in vivo were performed to investigate the effects of carcinostatic agents in the adhesion of cancer cells to endothelial cells. Certain carcinostatic agents induce the expression of E-selectin on endothelial cells and enhance the expression of carbohydrate ligands on cancer cells. Consequently, increased adhesion of cancer cells to endothelial cells was observed by the treatment of carcinostatic agents. In the trans-splenic hepatic metastasis model using nude mice, the augmentation of cancer metastasis was observed by the treatment of carcinostatic agents. From the above, we concluded that carcinostatic agents may increase the metastatic ability of cancer cells in patients with cancer.

Effect of ferrous ion on amino acid metabolism in mildiomycin production by Streptoverticillium rimofaciens

The physiological features of the mildiomycin production by Streptoverticillium rimofaciens were examined in iron-sufficient and -deficient media. Activities of NADP-linked glutamate dehydrogenase (GDH) and aspartate aminotransferase (AAT) were markedly enhanced by the addition of 10 micrograms/ml of ferrous ion into culture. Ammonium nitrogen assimilation increased with the increase in mildiomycin production. These indicate that ferrous ion contributes the supply of amino acids as a precursor of mildiomycin production. In the iron-sufficient medium, glutamate, aspartate, serine and arginine in cells were 2 to 10-fold to those in the iron-deficient medium. The major amino acid excreted from cells was arginine in the iron-sufficient culture, while in the iron-deficient culture, valine. Change in the amino acid profile by addition of ferrous ion was useful for mildiomycin biosynthesis, in which ferrous ion played a leading role in amino acid metabolism.

[Diagnosis of local recurrence of colorectal cancer, using PET and immunoscintigraphy by means of 131I or 111In anti-CEA monoclonal antibody]

The accurate and early diagnosis of the tumor in the point of the size, the location, the depth of invasion of other organs or the stages of the recurrent cancer became much more important than before, not only for the selection of the treatment method but also for the decision of the quality of the operation for preserving the function as much as possible for the quality of the life of the patient. The usefulness of positron emission tomography (PET) and immunoscintigraphy by means of 131I or 111In anti-CEA onoclonal antibody for the diagnosis of the recurrent colorectal cancer had been confirmed in clinical use of colorectal cancers. No adverse effect of this monoclonal anti-body of the mouse was seen in this studies. The differential absorption ratio (DAR) was useful indicator in PET-imaging to differentiate the true tumor tissue from the scar tissue or granulation-tissue around the tumor. Even though the imaging, structure of PET is inferior to those of CT or MRI, the imaging of PET reflects the biological character of tumor, itself and makes the more accurate diagnosis possibly by combined use with regular CT and MRI.

Peritoneal dissemination is inhibited by treatment with antibodies against CD44H, beta(1) integrin, and carcinostatic agents in NUGC-4 human gastric cancer cells

Peritoneal dissemination frequently occurs after surgery in patients with gastric cancer. The presence of peritoneal metastasis after surgery affects the prognosis, therefore, a way must be found to effectively prevent the development of peritoneal dissemination. Very little is known about the biochemical processes involved in the initial attachment of gastric cancer cells to peritoneal mesothelial cells. We conducted in vitro and in vivo studies to assess the role of adhesion molecules and TGF-beta 1 in this process, using 4 gastric cancer cell lines. NUGC-4 cells, which disseminate early after inoculation into the abdominal cavity of nude mice, predominantly expressed CD44H and beta(1) integrin. We found that NUGC-4 cells adhered to monolayers of mesothelial cells more firmly than other cell lines. Adhesion of NUGC-4 cells to mesothelial cells was partially inhibited by antibodies against CD44H or the beta(1) subunit of integrin, and was completely blocked by a combination of these 2 antibodies. Treatment with ligands for CD44H and beta(1) integrin also inhibited this adhesion. In the NUGC-4 cell culture medium, larger amounts of transforming growth factor beta 1(TGF-beta 1) was detected in proportion to the increase in cancer cells than in the other cell lines. TGF-beta 1 increased the expression of CD44H in NUGC-4 cells and in mesothelial cells, and augmented the adhesion and implantation of NUGC-4 cells to mesothelial cells accompanied by accumulation of extracellular matrix (ECM) components. Carcinostatic agents decreased the expression of CD44H but increased the expression of E-cadherin in NUGC-4 cells. Treatment with carcinostatic agents and antibodies against CD44H and beta(1) integrin inhibited the dissemination of NUGC-4 cells in the peritoneal cavity of nude mice, and prolonged their survival time. These findings suggest that CD44H and integrins mediate in the initial attachment of gastric cancer cells to mesothelial cells, and TGF-beta 1 participates in the promotion of the disease. It is possible that a treatment strategy that interferes with CD44H or integrins function and increases the functions of E-cadherin immediately after surgery may result in the decreased intra-abdominal spread of gastric cancer.

In vitro and in vivo induction of apoptosis by sphingosine and N, N-dimethylsphingosine in human epidermoid carcinoma KB-3-1 and its multidrug-resistant cells

Sphingolipid breakdown products, including ceramide and sphingosine, regulate cell growth, cell differentiation, and apoptosis. We examined the effect of various agents, including sphingolipids, on apoptosis induction in human epidermoid carcinoma KB-3-1 and its multidrug-resistant (MDR) subclone KB-C2 cells which express P-glycoprotein. Adriamycin (ADM) induced apoptosis in KB-3-1 cells but not in KB-C2 MDR cells at the concentration of 50 microg/ml. On the other hand, 15 microM sphingosine or its methylated derivative N, N-dimethylsphingosine (DMS) induced apoptosis in both cell types in vitro. These results suggested that KB-C2 MDR cells were resistant to apoptosis induction by ADM but sensitive to that by sphingosine and DMS. Ceramide and sphingosine-1-phosphate, the initial metabolites of sphingosine, failed to induce apoptosis under the same experimental condition as sphingosine/DMS. The protein kinase C (PKC) inhibitors H7 and staurosporine did not induce apoptosis in either cell line, suggesting that PKC-independent signaling is involved in apoptosis induced by sphingosine and DMS, although both sphingosine and DMS have been shown to down-regulate PKC. Furthermore, DMS significantly inhibited the growth of KB-3-1 as well as KB-C2 MDR tumors in vivo, with evidence of increased apoptosis. The intracellular level of exogenously added [3H]sphingosine or [14C]DMS did not differ between the KB-3-1 parent cell line and its MDR subclone KB-C2, whereas that of [14C]ADM was reduced in KB-C2 MDR cells compared to KB-3-1 cells. These results suggest that P-glycoprotein acts as a transporter for ADM but not for sphingosine or DMS. Furthermore, DMS at the concentrations which induce apoptosis in KB-C2 cells did not affect the level of [14C]ADM. Because sphingosine and DMS induce apoptosis regardless of P-glycoprotein expression, they may provide a new strategy and a promising approach to the treatment of anticancer drug-resistant cancer.

Bone morphogenetic protein-2 inhibits terminal differentiation of myogenic cells by suppressing the transcriptional activity of MyoD and myogenin

Bone morphogenetic protein (BMP) is a family of cytokines that induce ectopic bone formation when implanted into muscular tissues. We reported that BMP-2 inhibits the terminal differentiation of C2C12 myoblasts and converts them into osteoblast lineage cells (Katagiri, T., Yamaguchi, A., Komaki, M., Abe, E., Takahashi, N., Ikeda, T., Rosen, V., Wozney, J. M., Fujisawa-Sehara, A., and Suda, T. (1994) J. Cell Biol. 127, 1755-1766). In the present study, we examined the molecular mechanism of the inhibitory effect of BMP-2 on terminal differentiation of myogenic cells. When either MyoD or myogenin cDNA was introduced into C3H10T1/2 (10T1/2) cells with a muscle-specific CAT reporter containing four copies of the right E-box of muscle creatine kinase (MCK) enhancer, the CAT activity was dose-dependently suppressed by BMP-2. Furthermore, BMP-2 inhibited the terminal differentiation of these subclonal 10T1/2 cells that stably expressed MyoD or myogenin into mature myotubes that expressed myosin heavy chain and troponin T. The differentiation of a subclone of the MyoD-transfected NIH3T3 cells into mature muscle cells was also inhibited by BMP-2. BMP-2 induced alkaline phosphatase activity in 10T1/2-derived, but not in NIH3T3-derived MyoD-transfected cells. These cells constitutively expressed exogenous MyoD and myogenin, which were localized exclusively in the nuclei irrespective of the presence and the absence of BMP-2. However, these cells failed to express the mRNAs of endogenous myogenic factors and MCK when cultured with BMP-2. In the electrophoresis mobility shift assay using nuclear extracts of the myogenic cells, MyoD and myogenin bound to the right E-box in the enhancer region of the MCK gene even in the presence of BMP-2. These results suggest that BMP-2 inhibits the terminal differentiation of myogenic cells by suppressing the transcriptional activity of the myogenic factors.

Lung resistance protein (LRP) expression in human normal tissues in comparison with that of MDR1 and MRP

MDR1 (P-glycoprotein), multidrug resistance-associated protein (MRP) and lung resistance protein (LRP) are associated with multidrug resistance in various cancer cells. It is known that P-glycoprotein and MRP are also expressed in several normal tissues. However, the exact location of LRP in normal tissues is still unclear. In order to obtain more insight into the physiological role of LRP, its expression in human normal tissues was examined by an immunohistochemical technique, using one monoclonal antibody, LRP-56. Reverse transcriptase-polymerase chain reaction (RT-PCR) was also utilized for several cell lines and fresh-frozen tissues. P-glycoprotein was found to be expressed in the kidney, adrenal, brain vessels, muscle, lung, pancreas, liver, intestine, placenta and testis. MRP was expressed in the kidney, adrenal, lung, pancreas, muscle, intestine, thyroid and prostate, and its distribution mostly overlapped with that of P-glycoprotein. Interestingly, MRP was not expressed in the liver. LRP at 110 kDa was expressed in the kidney, adrenal, heart, lung, muscle, thyroid, prostate, bone marrow and testis. These findings suggest that LRP as well as P-glycoprotein and MRP plays distinct roles in the physiology of various organs.

Thymidine phosphorylase activity required for tumor angiogenesis and growth

Thymidine phosphorylase (TP) is identical to platelet-derived endothelial cell growth factor (PD-ECGF), and has angiogenic activity. We examined the involvement of TP activity in tumor growth and angiogenesis. KB cells were transfected with wild-type or mutant (L148R) PD-ECGF cDNA, and two sublines with high TP activity, KB/wt4 and KB/wt6, and one subline with no TP activity, KB/L148R, were cloned, respectively. The doubling times of these subclones in vitro were similar to that of KB cells. However, the growth of KB/wt4 and KB/wt6 cells was significantly faster when xenografted into nude mice than that of control cells with no TP activity. The tumors with high TP activity (KB/wt4 and KB/wt6) had significantly more microvessels than those with no TP activity (KB/-, KB/CV and KB/L148R) (P<0.01). These results, taken together with previous reports, suggest that the TP enzyme activity itself is involved in angiogenesis and growth of the KB tumors.

Adhesion of human gastric and pancreatic cancer cells to peritoneal mesothelial cells is mediated by CD44 and beta(1) integrin

Peritoneal dissemination is a common cause of the recurrence of gastric or pancreatic cancer after patients have undergone surgery. The presence of peritoneal metastasis after surgery affects the prognosis of patients with gastric or pancreatic cancer. Very little is known about the biochemical processes involved in the initial attachment of cancer cells to peritoneal mesothelial cells. We conducted in vitro and in vivo studies to assess the role of adhesion molecules in this process, using 5 cell lines derived from human gastric and pancreatic cancers. NUGC-4 and SW1990 cells, which disseminate earlier than the other 3 types of cancer cells after inoculation into the abdominal cavity of nude mice, express large amounts of CD44H. We found that NUGC-4 and SW1990 cells adhere to monolayers of mesothelial cells more firmly than the other cell lines, as shown by adhesion assays performed at 4 degrees C. The adhesion of NUGC-4 and SW1990 cells to mesothelial cells was partially inhibited by antibodies against CD44H or the beta(1) subunit of integrin, and they almost completely blocked adhesion when these 2 antibodies were used in combination in vitro. These 2 antibodies also inhibited the peritoneal metastasis of NUGC-4 and SW1990 cells and prolonged their mean survival time in vivo. These findings suggest that CD44H and beta(1) integrin play important roles in the initial attachment of gastric and pancreatic cancer cells to mesothelial cells. Our results suggest that changes in the expression of CD44H and beta(1) integrin in cancer cells is associated with their ability to adhere to peritoneal mesothelial cells, and thus with the peritoneal metastatic ability of gastric and pancreatic cancer cells. Therefore, the expression of CD44H and beta(1) integrin in gastric and pancreatic cancers could be used as prognostic indicators of peritoneal metastasis. It is possible that a treatment strategy that interferes with the functions of CD44H or beta(1) integrin may result in decreased intra-abdominal spread of cancer.