Hiroya Oka

Constitutive activation of the 41-/43-kDa mitogen-activated protein kinase signaling pathway in human tumors

The 41-kDa and 43-kDa mitogen-activated protein (MAP) kinases play a pivotal role in the mitogenic signal transduction pathway and are essential components of the MAP kinase cascade, which includes MAP kinase kinase (MEK) and Raf-1. As aberrant activation of signal transducing molecules such as Ras and Raf-1 has been linked with cancer, we examined whether constitutive activation of the 41-/43-kDa MAP kinases is associated with the neoplastic phenotype of 138 tumor cell lines and 102 primary tumors derived from various human organs. Constitutive activation of the MAP kinases was observed in 50 tumor cell lines (36.2%) in a rather tissue-specific manner: cell lines derived from pancreas, colon, lung, ovary and kidney showed especially high frequencies with a high degree of MAP kinase activation, while those derived from brain, esophagus, stomach, liver and of hematopoietic origin showed low frequencies with a limited degree of MAP kinase activation. We also detected constitutive activation of the 41-/43-kDa MAP kinases in a relatively large number of primary human tumors derived from kidney, colon and lung tissues but not from liver tissue. Many tumor cells, in which point mutations of ras genes were detected, showed constitutive activation of MAP kinases, however, there were also many exceptions to this observation. In contrast, the activation of the 41-/43-kDa MAP kinases was accompanied by the activation of Raf-1 in the majority of tumor cells and was completely associated with the activation of MEK and p90rsk in all the tumor cells examined. These results suggest that the constitutive activation of 41-/43-kDa MAP kinases in tumor cells is not due to the disorder of MAP kinases themselves, but is due to the disorder of Raf-1, Ras, or some other signaling molecules upstream of Ras.

Constitutive Activation of Mitogen-activated Protein (MAP) Kinases in Human Renal Cell Carcinoma

Mitogen-activated protein kinases (MAPKs) play a pivotal role in the mitogenic signal transduction pathway and are essential components of the MAPK cascade, which includes MEK (also known as MAP kinase kinase), Raf-1, and Ras. In this study, we examined whether constitutive activation of the MAPK cascade was associated with the carcinogenesis of human renal cell carcinomas in a series of 25 tumors and in corresponding normal kidneys. Constitutive activation of MAPKs in tumor tissue, as determined by the appearance of phosphorylated forms, was found in 12 cases (48%), and this activation was confirmed by a direct in vitro kinase assay of immunoprecipitate using myelin basic protein as the substrate. The phosphorylation of MEK and of Raf-1, as monitored by a mobility shift in SDS-PAGE, which is reportedly associated with the activation of these kinases, occurred in 9 of 18 cases (50%) and in 6 of 11 cases (55%) respectively. The activation of MAPKs was correlated with MEK activation (P = 0.0045) and with Raf-1 activation (P = 0.067). Furthermore, overexpression of MEK was found in 13 of 25 cases (52%) by Western blot analysis, and this overexpression was associated significantly with MAPK activation (P = 0.034). No mutations were noted in H-,K-, or N-ras genes by PCR direct sequencing in any of the 25 tumor samples. Of the patients studied, 8 of 18 (44%) stage pT2 patients and four of six (67%) stage pT3 patients showed MAPK activation. The single stage pT1 patient did not evidence MAPK activation. Furthermore, one of seven (14%) grade 1 patients, 9 of 13 (69%) grade 2 patients, and two of five (40%) grade 3 patients showed MAPK activation (grade 1 versus grades 2 and 3, P = 0.046). Our results suggest that constitutive activation of MAPKs may be associated with the carcinogenesis of human RCCs.

PEBP2 alpha B/mouse AML1 consists of multiple isoforms that possess differential transactivation potentials.

A murine transcription factor, PEBP2, is composed of two subunits, alpha and beta. There are two genes in the mouse genome, PEBP2 alpha A and PEBP2 alpha B, which encode the alpha subunit. Two types of the alpha B cDNA clones, alpha B1 and alpha B2, were isolated from mouse fibroblasts and characterized. They were found to represent 3.8- and 7.9-kb transcripts, respectively. The 3.8-kb RNA encodes the previously described alpha B protein referred to as alpha B1, while the 7.9-kb RNA encodes a 387-amino-acid protein, termed alpha B2, which is identical to alpha B1 except that it has an internal deletion of 64 amino acid residues. Both alpha B1 and alpha B2 associate with PEBP2 beta and form a heterodimer. The alpha B2/beta complex binds to the PEBP2 binding site two- to threefold more strongly than the alpha B1/beta complex does. alpha B1 stimulates transcription through the PEBP2 site about 40-fold, while alpha B2 is only about 25 to 45% as active as alpha B1. Transactivation domain is located downstream of the 128-amino-acid runt homology region, referred to as the Runt domain. Mouse chromosome mapping studies revealed that alpha A, alpha B, and beta genes are mapped to chromosomes 17, 16, and 8, respectively. The last two genes are syntenic with the human AML1 on chromosome 21q22 and PEBP2 beta/CBF beta on 16q22 detected at the breakpoints of characteristic chromosome translocations of the two different subtypes of acute myeloid leukemia. These results suggest that previously described chimeric gene products, AML1/MTG8(ETO) and AML1-EAP generated by t(8;21) and t(3;21), respectively, lack the transactivation domain of AML1.

Androgen receptor CAG repeat length polymorphism in benign prostatic hyperplasia (BPH): Correlation with adenoma growth†

The androgen receptor (AR) gene has a polymorphic CAG microsatellite encoding variable‐length glutamine repeats in the AR protein. The purpose of this study was to evaluate the association between the growth of benign prostatic hyperplasia (BPH) and the AR gene CAG repeat length.

SERUM C-REACTIVE PROTEIN LEVEL AND THE IMPACT OF CYTOREDUCTIVE SURGERY IN PATIENTS WITH METASTATIC RENAL CELL CARCINOMA

PURPOSE The prognosis of metastatic renal cell carcinoma is extremely poor. In this type of metastatic tumor cytoreductive surgery of the primary tumor is often performed to confirm the histological type or improve the response to immunotherapy with agents such as interferon or interleukin-2. However, the timing and impact of cytoreductive surgery on the success of immunotherapy require further study. We determined the type of metastatic renal cell carcinoma for which cytoreductive surgery is beneficial. MATERIALS AND METHODS We retrospectively reviewed the records of 58 patients in whom metastatic renal cell carcinoma was diagnosed at our hospital between 1986 and 1997. Three patients were excluded from study because they were judged to be poor candidates for surgery due to poor performance status. Of the remaining 55 patients 34 consented to cytoreductive surgery of the primary tumor and 21 did not. All except 1 patient were treated with interferon therapy. We evaluated the association of pretreatment serum C-reactive protein and the effect of surgery. RESULTS We noted no significant difference in age at diagnosis, pretreatment serum immunosuppressive acidic protein, site of metastasis or performance status in 34 patients who underwent cytoreductive surgery and 21 who did not. Of the 21 patients in whom pretreatment serum C-reactive protein was within normal limits (less than 1.0 ng./ml.) no significant difference in disease specific survival was observed in those who did and did not undergo surgery (p = 0.4133). On the other hand, of 34 patients in whom pretreatment serum C-reactive protein was elevated (1.0 ng./ml. or greater) the prognosis was significantly better in those who did versus those who did not undergo surgery (p = 0.0054). Particularly the prognosis in patients in whom postoperative nadir C-reactive protein decreased to within normal limits was markedly better than in those in whom it remained elevated (p = 0.0025). CONCLUSIONS Our study suggests that cytoreductive surgery is beneficial to patients in whom pretreatment serum C-reactive protein is elevated. Particularly, those in whom serum C-reactive protein decreases to within normal limits may expect longer survival when surgery is combined with postoperative immunotherapy. Currently to our knowledge the prognostic factor that predicts postoperative nadir C-reactive protein has not been identified, indicating that cytoreductive surgery of the primary tumor should be performed in patients with elevated pretreatment C-reactive protein and as performance status permits.

SERUM IMMUNOSUPPRESSIVE ACIDIC PROTEIN AND NATURAL KILLER CELL ACTIVITY IN PATIENTS WITH METASTATIC RENAL CELL CARCINOMA BEFORE AND AFTER NEPHRECTOMY

PURPOSE To our knowledge the impact of nephrectomy on stage M1 renal cell carcinoma remains to be determined. We previously reported that nephrectomy is beneficial in patients with elevated serum C-reactive protein before treatment, and those in whom nadir C-reactive protein decreases postoperatively to within the normal range may expect longer survival when surgery is combined with postoperative immunotherapy. In this study we determine the effect of nephrectomy on the immune response in patients with metastatic renal cell carcinoma. MATERIALS AND METHODS We retrospectively reviewed the records of 40 patients with metastatic renal cell carcinoma diagnosed at our institution between 1986 and 1999. These patients underwent nephrectomy before cytokine therapy with interferon. Before and after nephrectomy we measured serum C-reactive protein, serum immunosuppressive acidic protein and peripheral blood natural killer cell activity. RESULTS In 15 patients with pretreatment serum C-reactive protein within the normal range (less than 1 ng./ml.) there was no significant difference before and after nephrectomy in the serum immunosuppressive acidic protein level or natural killer cell activity (p = 0.4587 and 0.3892, respectively). On the other hand, in 25 patients with serum C-reactive protein elevated before treatment to 1 ng./ml. or greater serum immunosuppressive acidic protein decreased significantly and natural killer cell activity increased significantly after cytoreductive surgery (p = 0.0002 and 0.0286, respectively). CONCLUSIONS Our study implies that nephrectomy may be beneficial in patients with elevated serum C-reactive protein before treatment. Further evaluation by a prospective study is needed to make a definitive conclusion.

Myelomonoblastic leukaemia cells carrying the PEBP2β/MYH11 fusion gene are CD34+, c-KIT+ immature cells

To clarify the aspects affected by the PEBP2β/MYH11 fusion gene involved in the inv(16), we analysed immunophenotypes in myelomonoblastic leukaemias. We found high expressions of CD34 and c‐KIT antigens in myelomonoblastic cells from all patients carrying this fusion gene, including two with M4 and one CML blastic phase, in contrast to those with M4 without the fusion gene. These findings indicate that immunophenotyping is useful for detecting a leukaemia with the fusion gene in myelomonoblastic leukaemias and that the PEBP2β/MYH11 gene is involved in immature cells expressing CD34 and c‐KIT antigens.

Adrenal leiomyosarcoma extending into the right atrium.

Abstract Primary soft tissue sarcoma of the adrenal gland is very rare and aggressive. In right adrenal tumors, because of direct venous drainage into inferior vena cava, the tumor may invade the vena caval wall toward the right atrium. We present a case of adrenal leiomyosarcoma extending into the right atrium.

Telomerase activity in adrenal cortical tumors and pheochromocytomas with reference to clinicopathologic features

Abstract Telomeres consist of short repeated sequences that are shortened on continuous cell proliferations and synthesized by telomerase, an RNA-dependent DNA polymerase. Recent molecular studies have reported that telomerase is activated in most human cancers, whereas it is not detected in most somatic cells. These findings indicate that the positive telomerase activity is closely related to the malignant potential of human tumors. In several types of human tumors, including adrenal cortical tumors and pheochromocytomas, it is very difficult to predict the malignant potential using conventional histopathologic examination. To determine whether telomerase activity is useful as a diagnostic marker, we examined telomerase activity in adrenal cortical tumors and pheochromocytomas with special reference to their clinicopathologic features. Using a highly sensitive polymerase chain reaction (PCR)-based detection method, telomerase activity was demonstrated in one of 13 adrenal cortical tumors and two of seven pheochromocytomas, whereas all seven normal portions of adrenal gland failed to showed any telomerase activity. Although none of the tumors examined in this study was associated with metastasis, these three telomerase-positive tumors were accompanied by clinicopathologic features suggesting malignant potential. Telomerase activity might be a potential marker for estimating the biologic characteristics of adrenal cortical tumors and pheochromocytomas.

A CASE OF RENAL CELL CARCINOMA DURING PREGNANCY: SIMULTANEOUS CESAREAN SECTION AND RADICAL NEPHRECTOMY

A 32-year-old woman was referred to us with right flank pain and macroscopic hematuria at gestational week 22 of a second pregnancy. Abdominal Doppler ultrasonography and magnetic resonance imaging demonstrated a 14 3 15 3 16 cm. hypervascular tumor of the right kidney (fig. 1). Neither these studies nor a chest x-ray suggested involvement of other organs, including the right renal vein, liver and lungs. Blood tests revealed no abnormalities, except mild anemia. The patient and spouse wished to save the life of the fetus. After consultation with obstetricians, pediatricians and anesthesiologists, we performed right radical nephrectomy and cesarean section at gestational week 28. On March 9, 1999 a 1,065 gm. fetus was delivered transabdominally. A 1,500 gm. specimen, including the right kidney and a round, nonadherent tumor, was removed following cephalad extension of the lower abdominal midline incision for cesarean section. Pathological examination revealed chromophobe type pT2pN0M0 renal cell carcinoma (fig. 2). The patient and child were well at 9-month followup.