Mechanisms of L-DOPA-induced cytotoxicity in rat adrenal pheochromocytoma cells: implication of oxidative stress-related kinases and cyclic AMP

L-DOPA therapy for Parkinson's disease has a double-edge effect on nigrostriatal dopaminergic neurons: L-DOPA increases the intracellular level of dopamine, but it induces neuron cytotoxicity in a concentration-dependent manner. To investigate the molecular signaling mechanisms that underlie the concentration-dependent effects of L-DOPA on cell viability, the activities of mitogen-activated protein kinases (MAPKs) and apoptotic enzymes were measured in rat adrenal pheochromocytoma (PC12) cells in the presence of a low concentration (20 muM) and high concentrations (100-200 muM) of L-DOPA. At the low concentration, L-DOPA was not cytotoxic and its presence increased the activities of extracellular signal-regulated kinase (ERK)1/2, p38 MAPK, BadSer112, Bcl-2, and caspase-12. At the high concentrations, L-DOPA was cytotoxic and stimulated the activities of ERK1/2, p38 MAPK, c-Jun N-terminal kinase (JNK)1/2, BadSer155, caspase-12 and caspase-3. The increased levels of ERK1/2 and BadSer155 in the presence of high concentrations of L-DOPA did not protect against L-DOPA-mediated cytotoxicity. In addition, the levels of L-type Ca(2+) channel-sensitive intracellular cyclic AMP (cAMP) and Ca(2+) were elevated in the presence of L-DOPA, and the increase in the levels of intracellular cAMP may also play a role in cellular viability, since cAMP levels and cytotoxicity increased in parallel with L-DOPA concentrations and the addition of forskolin in the medium increased cytotoxicity in a concentration-dependent manner. These results suggest that, at a low and non-toxic concentration, L-DOPA may promote cell survival by increasing the activities of ERK1/2, BadSer112 and Bcl-2, while, at high concentrations, L-DOPA activates the caspase-3 cell death enzyme through the JNK1/2 and p38 MAPK signaling pathways as well as endoplasmic reticulum stress that activates caspase-12. Intracellular cAMP levels may also play a role here. The results may lead to an effective therapy for Parkinson's disease.

DNA methylation of interferon regulatory factors in gastric cancer and noncancerous gastric mucosae

Interferon regulatory factors (IRFs) are transcription factors known to play key roles in innate and adaptive immune responses, cell growth, apoptosis, and development. Their function in tumorigenesis of gastric cancer remains to be determined, however. In the present study, therefore, we examined epigenetic inactivation of IRF1-9 in a panel of gastric cancer cell lines. We found that expression of IRF4, IRF5, and IRF8 was frequently suppressed in gastric cancer cell lines; that methylation of the three genes correlated with their silencing; and that treating the cells with the demethylating agent 5-aza-2'-deoxycytidine (DAC) restored their expression. Expression of IRF5 in cancer cells was enhanced by the combination of DAC treatment and adenoviral vector-mediated expression of p53, p63, or p73. Interferon-gamma-induced expression of IRF8 was also enhanced by DAC. Moreover, treating gastric cancer cells with DAC enhanced the suppressive effects of interferon-alpha, interferon-beta, and interferon-gamma on cell growth. Among a cohort of 455 gastric cancer and noncancerous gastric tissue samples, methylation of IRF4 was frequently observed in both gastric cancer specimens and noncancerous specimens of gastric mucosa from patients with multiple gastric cancers, which suggests IRF4 methylation could be a useful molecular marker for diagnosing recurrence of gastric cancers. Our findings indicate that epigenetic IRF inactivation plays a key role in tumorigenesis of gastric cancer, and that inhibition of DNA methylation may restore the antitumor activity of interferons through up-regulation of IRFs.

Hedgehog Signaling Pathway Is a New Target of Cancer Stem Cell Therapy for Breast Cancer Patients

Introduction: Hedgehog (Hh) signaling pathway is crucial for growth and patterning during embryonic development. We have shown that Hh pathway is constitutively reactivated in human breast cancer (Kubo M et al. Cancer Res 2004). Recently, it has been proposed that only a small subset, termed cancer stem cells (CSCs), posseses tumorigenicity. And, several investigations suggest contributions of morphogenesis pathways including Hh pathway in the maintenance of CSCs. Purpose of this study is to reveal an essential role of Hh pathway in the maintenance of CSCs, and also to reveal a possibility of Hh pathway as a target of CSCs therapy for breast cancer patients.Materials and Methods: A human breast cancer cell line MCF-7 was used. In the present study, we estimated CD44+CD24-/low cells or side population (SP) cells as CSCs. Flow cytometric analysis and sorting were performed to detect and collect CSCs, respectively. To confirm the high tumorigenicity of CSCs, we used a MCF-7 cell xenograft mouse model in NOD/SCID mice. To assess the expression of Hh pathway-related molecules, real-time RT-PCR and fluorescent immunostaining were performed. For blockade of Hh pathway, a Hh inhibitor, cyclopamine, and small interference RNA (si-RNA) against Gli1, a trans-activator of the Hh pathway, were used. We also synthesized peptides with specific affinity for a transmembrane receptor Patched1 (Ptch1).Results: CD44+CD24-/low cells and SP cells in total MCF-7 cells were 10-25% and 1-4%, respectively and these two populations were overlapped with each other. These CSCs were highly tumorigenic, and resistant to anticancer drugs including taxanes.Hh pathway-related molecules such as Shh, a ligand of Hh pathway, and Gli1 were predominantly expressed in CSCs. Cyclopamine and Ptch1 affinitive peptides could suppress the tumorigenicity of CSCs in NOD/SCID mice xenograft transplantation model.Conclusions: Hh pathway at least partly contributes to the maintenance of CSCs in MCF-7 cells. Thus, Hh pathway may be a valuable therapeutic target for CSCs therapy for breast cancer patients.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1161.

Diacylglycerol kinase eta augments C-Raf activity and B-Raf/C-Raf heterodimerization

The Ras/B-Raf/C-Raf/MEK/ERK signaling cascade is critical for the control of many fundamental cellular processes, including proliferation, survival, and differentiation. This study demonstrated that small interfering RNA-dependent knockdown of diacylglycerol kinase eta (DGKeta) impaired the Ras/B-Raf/C-Raf/MEK/ERK pathway activated by epidermal growth factor (EGF) in HeLa cells. Conversely, the overexpression of DGKeta1 could activate the Ras/B-Raf/C-Raf/MEK/ERK pathway in a DGK activity-independent manner, suggesting that DGKeta serves as a scaffold/adaptor protein. By determining the activity of all the components of the pathway in DGKeta-silenced HeLa cells, this study revealed that DGKeta activated C-Raf but not B-Raf. Moreover, this study demonstrated that DGKeta enhanced EGF-induced heterodimerization of C-Raf with B-Raf, which transmits the signal to C-Raf. DGKeta physically interacted with B-Raf and C-Raf, regulating EGF-induced recruitment of B-Raf and C-Raf from the cytosol to membranes. The DGKeta-dependent activation of C-Raf occurred downstream or independently of the already known C-Raf modifications, such as dephosphorylation at Ser-259, phosphorylation at Ser-338, and interaction with 14-3-3 protein. Taken together, the results obtained strongly support that DGKeta acts as a novel critical regulatory component of the Ras/B-Raf/C-Raf/MEK/ERK signaling cascade via a previously unidentified mechanism.

Hepatic resection is justified for elderly patients with hepatocellular carcinoma

BACKGROUND

Hepatic resection is one of the main treatment modalities for patients with hepatocellular carcinoma (HCC); however, surgery is generally stressful and often is avoided for elderly patients. This retrospective study was designed to determine whether the indications for hepatic resection in younger patients with HCC are applicable to elderly patients.

METHODS

Subjects were 294 patients in whom 319 hepatic resections were performed for HCC (male/female ratio, 238/81; age range, 18-83 years). The patients were divided into two groups according to age at the time of surgery: 70 years or older (n = 109) and 69 years or younger (n = 210). Surgical strategy and postoperative follow-up methods did not differ between groups. The incidence and severity of postoperative complications classified by the Clavien system were compared between the two groups. Postoperative survival was compared between the two groups and between subgroups based on Japan Integrated Staging (JIS) scores. HCC-related death rates also were compared.

RESULTS

No significant between-group difference was found in background liver function or type of hepatic resection. Differences were found in performance status and type of hepatitis virus infection. No difference was observed in the incidence or severity of postoperative complications. Postoperative survival was similar between the two age-based study groups and between the JIS-based subgroups. HCC-related death rates did not differ between groups.

CONCLUSIONS

The absence of differences in postoperative outcomes between groups suggests that hepatic resection is justified for HCC in selected patients aged 70 years or older.

IGFBP7 is a p53-responsive gene specifically silenced in colorectal cancer with CpG island methylator phenotype

A subset of colorectal cancers (CRCs) show simultaneous methylation of multiple genes; these tumors have the CpG island methylator phenotype (CIMP). CRCs with CIMP show a specific pattern of genetic alterations, including a high frequency of BRAF mutations and a low frequency of p53 mutations. We therefore hypothesized that genes inactivated by DNA methylation are involved in the BRAF- and p53-signaling pathways. Among those, we examined the epigenetic inactivation of insulin-like growth factor-binding protein 7 (IGFBP7) expression in CRCs. We found that in CRC cell lines, the silencing of IGFBP7 expression was correlated with high levels of DNA methylation and low levels of histone H3K4 methylation. Luciferase and chromatin immunoprecipitation assays in unmethylated cells revealed that p53 induces expression of IGFBP7 upon binding to a p53 response element within intron 1 of the gene. Treating methylated CRC cell lines with 5-aza-2'-deoxycytidine restored p53-induced IGFBP7 expression. Levels of IGFBP7 methylation were also significantly higher in primary CRC specimens than in normal colonic tissue (P < 0.001). Methylation of IGFBP7 was correlated with BRAF mutations, an absence of p53 mutations and the presence of CIMP. Thus, epigenetic inactivation of IGFBP7 appears to play a key role in tumorigenesis of CRCs with CIMP by enabling escape from p53-induced senescence.

Surgical strategy for hepatocellular carcinoma patients with portal vein tumor thrombus based on prognostic factors

RATIONALE

Surgical strategy for patients with hepatocellular carcinoma and portal vein tumor thrombus (PVTT) remains to be established.

METHODS

From 1990 to 2008, 48 hepatocellular carcinoma patients with PVTT detected by preoperative imaging underwent hepatic resection, and their clinical data were retrospectively analyzed. Possible prognostic factors for survival were analyzed with postoperative survival curves, and significant factors were determined by univariate and multivariate analysis. The frequency of postoperative severe complications was investigated for each prognostic factor.

RESULTS

Significant prognostic factors included patient age <60 years, serum total bilirubin (T-Bil) >0.8 mg/dl, serum aspartate aminotransferase >30 IU/L, serum alkaline phosphatase (ALP) >300 IU/L, tumor size >4 cm, PVTT in the main trunk (Vp4), and a surgical margin <1 mm by univariate analysis, and independent prognostic factors were serum T-Bil, ALP, and Vp4. No patient with Vp4 survived for more than 400 days after surgery, and frequency of postoperative severe complications in these Vp4 patients was significantly higher than in other Vp1-3 patients.

CONCLUSION

Hepatic resection as a first-choice treatment should be carefully selected in patients with Vp4 unless emergent removal of the PVTT is required.

Diacylglycerol kinase delta associates with receptor for activated C kinase 1, RACK1

The delta-isozyme (type II) of diacylglycerol kinase (DGK) is known to positively regulate growth factor receptor signaling. DGKdelta, which is distributed to clathrin-coated vesicles, interacts with DGKdelta itself, protein kinase C and AP2alpha. To search for additional DGKdelta-interacting proteins, we screened a yeast two-hybrid cDNA library from HepG2 cells using aa 896-1097 of DGKdelta as a bait. We identified aa 184-317 (WD40 repeats 5-7) of receptor for activated C kinase 1 (RACK1), which interacts with various important signaling molecules, as a novel binding partner of DGKdelta. Co-immunoprecipitation analysis, using COS-7 cells co-expressing RACK1 and DGKdelta, revealed that RACK1 selectively interacted with DGKdelta, but not with type I DGKs, in mammalian cells. The interaction was dynamically regulated by phorbol ester. Intriguingly, DGKdelta appeared to recruit RACK1 to clathrin-coated vesicles and co-localized with RACK1. These results suggest that DGKdelta serves as an adaptor protein to regulate the localization of the versatile scaffold protein, RACK1.

Myocardial DNA strand breaks are detected in biopsy tissues from patients with dilated cardiomyopathy

BACKGROUND

Progressive damage of cardiomyocytes with interstitial and replacement fibrosis accompanied by less inflammatory cell infiltration is observed in patients with dilated cardiomyopathy (DCM), suggesting some other mechanisms rather than necrotic cell death.

HYPOTHESIS

The aim of this study was to assess the possible involvement of apoptotic process in the pathogenesis of DCM and myocarditis.

METHODS

Endomyocardial biopsy was performed in patients with DCM (n = 9), myocarditis (n = 4), or atypical chest pain syndrome (as controls; n = 5). The TUNEL method was used for in situ detection of oligonucleosomal DNA strand breaks.

RESULTS

The TUNEL-positive cells were observed in three of nine patients with DCM and in all four with myocarditis, but in none of the controls. The TUNEL-positive nuclei were observed exclusively in cardiomyocytes in DCM, whereas in myocarditis they were detected mainly in interstitial cells and in a few myocytes. In DCM, interstitial fibrosis was greater in the TUNEL-positive than in TUNEL-negative patients (p < 0.05). In either DCM or myocarditis, electron microscopic examination could not reveal morphologic features of apoptosis of cardiomyocytes.

CONCLUSION

The DNA strand breaks were detected in cardiomyocytes in patients with DCM and mainly in interstitial cells in myocarditis. It is possible that the DNA strand breaks can be involved in mechanisms of progressive loss of functional cardiac units in these myocardial diseases.

Differential expression of organic anion transporters in rats subjected to 70% or 90% hepatectomy

BACKGROUND/AIMS

Differences in hepatic organic anion transporters were compared in rats to identify a causative factor for early stage acute hepatic failure after 70% or 90% hepatectomy (Hx).

METHODOLOGY

Male Wistar rats (8 weeks, 250-330g) were randomly assigned to one of two groups for 70% Hx or 90% Hx, and sacrificed at 0, 6, 12, 24, 48, or 72 hours after Hx. Posthepatectomy expression of the bile salt export pump (Bsep), multidrug resistance proteins 2 and 3 (Mrp2, Mrp3), sodium-dependent taurocholate co-transporting polypeptide (Ntcp), and organic anion transporting polypeptides 1 and 2 (Oatp1, Oatp2) were analyzed by Northern blotting. Serum liver function tests were also performed.

RESULTS

Postoperative survival rates at 72 hours after 70% and 90% Hx were 100% and 50%, respectively. mRNA expression of Bsep and Mrp3 was increased after 90% Hx, while decreased after 70% Hx. These values were significantly greater at 12 and 24 hours after 90% Hx than after 70% Hx (p < 0.05). In contrast, Mrp2 expression was downregulated to a half of the preoperative level after 90% Hx, while increased after 70% Hx. mRNA expression of uptake transporters (Ntcp, Oatp1, Oatp2) was decreased after 70% Hx and 90% Hx with a similar extent. Total serum bilirubin and bile acid levels were significantly increased after both hepatectomy procedures with a greater extent after 90% Hx.

CONCLUSIONS

Alteration of mRNA expression of Bsep, Mrp2 and Mrp3 may be characteristic behavior in the early stage of acute liver failure.

Prospective randomized controlled study of gastric emptying assessed by (13)C-acetate breath test after pylorus-preserving pancreaticoduodenectomy: comparison between antecolic and vertical retrocolic duodenojejunostomy

BACKGROUND/PURPOSE

To examine whether vertical retrocolic duodenojejunostomy is superior to antecolic duodenojejunostomy with respect to gastric emptying in a prospective, randomized, controlled study of patients undergoing pylorus-preserving pancreaticoduodenectomy (PpPD).

METHODS

Thirty-five patients undergoing PpPD between March 2005 and July 2007 were enrolled in the study. All provided informed consent. During PpPD, the patients were randomly assigned to either the antecolic (antecolic group, n = 17) or vertical retrocolic route (vertical retrocolic group, n = 18) just before the reconstruction. Each patient ingested (13)C-acetate in a liquid meal before surgery and on postoperative day (POD) 30. Gastric emptying variables (Tmax, T1/2) were determined and compared between groups.

RESULTS

Clinical delayed gastric emptying, defined as an inability of patients to take in an appropriate amount of solid food orally by POD 14, was found in 1 of 17 patients (6%) in the antecolic group and in 4 of 18 patients (22%) in the vertical retrocolic group, but the difference was not significant (P = 0.34). Tmax and T1/2 on POD 30 were prolonged in both groups in comparison to preoperative levels, but no significant difference was found between the two groups. Follow-up examinations revealed that gastric emptying had recovered to the preoperative level by POD 30 in approximately 80% of the patients, regardless of the reconstruction route.

CONCLUSIONS

Vertical retrocolic duodenojejunostomy does not seem to offer an advantage with respect to gastric emptying.

Medical students' attitudes to laparoscopic surgery

BACKGROUND/AIMS

The purpose of the present study was to evaluate the attitude of medical students to laparosocopic surgery.

METHODOLOGY

Two hundred and seven medical students completed a questionnaire regarding their visualization of, understanding of, and interest in observation of laparoscopic surgery via laparoscopic monitor (laparoscopic observation) and of open surgery, either directly (open direct observation), or via video monitor observation (open monitor observation). They were also asked about their willingness to become an operator (operator). Responses to each item were given as Likert-type scores ranging from 1 to 5.

RESULTS

The visualization score was significantly lower for open direct observation than for open monitor observation (P<0.001) and laparoscopic observation (P<0.001), with the significantly lower score for open monitor observation than for laparoscopic observation (P<0.001). The understanding score was significantly lower for open direct observation than for open monitor observation (P<0.01) and laparoscopic observation (P<0.01). Interest scores did not differ between the three observation methods. The operator score was significantly higher for open surgery than for laparoscopic surgery.

CONCLUSIONS

Laparoscopic surgery provides good visualization of the operative field. However, students' interest in laparoscopic surgery is similar to those of open surgery.

Video monitoring and slide and video presentations as tools for surgical education

BACKGROUND/AIMS

To provide medical students with good visualization and understanding of surgical procedures, we used video monitoring (Monitor) in the operating room and slide (Slide) and video (Video) presentation in the conferences. The purpose of this study was to evaluate the effect of these visual aids on surgical education.

METHODOLOGY

One hundred and twenty-nine fifth- and sixth-year medical students completed a questionnaire regarding their visualization of, understanding of, and interest in all surgical procedures observed and procedures pertaining to their assigned patients. The score was collected on a Likert-type scores ranged from 1 for "poor" to 5 for "excellent".

RESULTS

Visualization and understanding scores were significantly lower for direct observation than for Monitor (p<0.01 and p<0.001), Slide (p<0.001 and p<0.001) and Video (p<0.001 and p<0.001). Interest scores did not differ between observation methods. For all observation methods, understanding of and interest in the surgical procedures were significantly greater in relation to assigned patients than in relation to all patients observed.

CONCLUSIONS

Video monitoring and slide and video presentations enhance students' understanding of and interest in surgical procedures. Contributing to the care of assigned patient also increases understanding of and interest in general surgery.

Outcome of surgical treatment of hilar cholangiocarcinoma

To evaluate surgical results and the effect of adjuvant chemotherapy in cases of hilar cholangiocarcinoma, we retrospectively analyzed 27 consecutive patients who underwent surgical resection (eight bile duct resections, 18 bile duct resections plus hepatectomy, one hepatopancreaticoduodenectomy). There was no operative mortality, and the morbidity was 37%. Curative resection (R0 resection) was achieved in 20 (74%) patients. Overall survival at 3 and 5 years was 44% and 27%, significantly higher than that of 47 patients who did not undergo resection (3.5% and 0% at 3 and 5 years, p < 0.0001). Survival of patients with positive margins (R1/2 resection) was poor; there were no 5-year survivors. However, survival was better than that of patients who did not undergo resection (median survival: 22 vs 9 months, p = 0.0007). Univariate analysis identified lymph node metastasis as a negative prognostic factor (p = 0.043). Median survival of patients who underwent adjuvant chemotherapy was significantly longer than that of patients who did not (42 vs. 22 months, p = 0.0428). Resection should be considered as the first option for hilar cholangiocarcinoma. There appears to be a survival advantage even in patients with cancer-positive margins. Adjuvant chemotherapy may increase long-term survival.

Differences in long-term outcome and prognostic factors according to viral status in patients with hepatocellular carcinoma treated by surgery

Long-term postoperative survival and prognostic factors were examined retrospectively in patients with hepatocellular carcinoma (HCC) with serum hepatitis B surface antigen (HBsAg) or hepatitis C antibody (HCVAb) and in those without virus infection. Subjects were 265 consecutive HCC patients treated surgically at one institution during the period 1990 to 2006. Postoperative survival was analyzed and compared between HBsAg-positive (B-HCC), HCVAb-positive (C-HCC), and hepatitis B- and C-negative (NBNC-HCC) patients. Prognostic factors for overall and recurrence-free survival were also analyzed. Overall and recurrence-free survival rates were significantly higher in the NBNC-HCC group than in the C-HCC group. Significant prognostic factors for overall survival identified by univariate and multivariate analyses were age, serum alkaline phosphatase (ALP) level, tumor multiplicity, portal vein invasion (Vp), hepatic vein invasion (Vv), and operative blood loss in the B-HCC group; serum albumin level, ALP level, tumor size, and Vv in the C-HCC group; and tumor multiplicity in the NBNC-HCC group. Significant factors for recurrence-free survival were age, ALP level, tumor multiplicity, Vp, and operation time in the B-HCC group; ALP level, prothrombin time, tumor size, Vv, and width of the surgical margin in the C-HCC group; and age, tumor size, tumor multiplicity, and Vp in the NBNC-HCC group. Thus, postoperative survival and prognostic factors in cases of HCC differ according to the presence of serologic viral markers.

Phorbol ester and hydrogen peroxide synergistically induce the interaction of diacylglycerol kinase gamma with the Src homology 2 and C1 domains of beta2-chimaerin

DGKgamma (diacylglycerol kinase gamma) was reported to interact with beta2-chimaerin, a GAP (GTPase-activating protein) for Rac, in response to epidermal growth factor. Here we found that PMA and H2O2 also induced the interaction of DGKgamma with beta2-chimaerin. It is noteworthy that simultaneous addition of PMA and H2O2 synergistically enhanced the interaction. In this case, PMA was replaceable by DAG (diacylglycerol). The beta2-chimaerin translocation from the cytoplasm to the plasma membrane caused by PMA plus H2O2 was further enhanced by the expression of DGKgamma. Moreover, DGKgamma apparently enhanced the beta2-chimaerin GAP activity upon cell stimulation with PMA. PMA was found to be mainly required for a conversion of beta2-chimaerin into an active form. On the other hand, H2O2 was suggested to induce a release of Zn2+ from the C1 domain of beta2-chimaerin. By stepwise deletion analysis, we demonstrated that the SH2 (Src homology 2) and C1 domains of beta2-chimaerin interacted with the N-terminal half of catalytic region of DGKgamma. Unexpectedly, the SH2 domain of beta2-chimaerin contributes to the interaction independently of phosphotyrosine. Taken together, these results suggest that the functional link between DGKgamma and beta2-chimaerin has a broad significance in response to a wide range of cell stimuli. Our work offers a novel mechanism of protein-protein interaction, that is, the phosphotyrosine-independent interaction of the SH2 domain acting in co-operation with the C1 domain.

Rab7 regulates maturation of melanosomal matrix protein gp100/Pmel17/Silv

Melanosome biogenesis consists of multistep processes that involve synthesis of melanosomal protein, which is followed by vesicle transport/fusion and post-translational modifications such as glycosylation, proteolysis, and oligomerization. Because of its complexity, the details of the molecular mechanism of melanosome biogenesis are not yet fully understood. Here, we report that, in MMAc melanoma cells, wild-type (WT) Rab7 and its dominant-active mutant (Rab7-Q67L), but not its dominant-negative mutant (Rab7-T22N), were colocalized in the perinuclear region with granules containing Stage I melanosomes, where the full-length, immature gp100/Pmel17/Silv was present. It was also found that overexpression of Rab7-Q67L and, to a lesser extent, Rab7-WT increased the amount of proteolytically processed, mature gp100. However, Rab7-T22N did not show such an effect. Moreover, siRNA-mediated Rab7 knockdown considerably inhibited gp100 maturation. These results collectively suggest that the GTP-bound form of Rab7 promotes melanogenesis through the regulation of gp100 maturation in melanoma cells.

Unusual segmental stricture of the lower common bile duct mimicking bile duct cancer

In some cases of bile duct stricture, malignancy cannot be diagnosed preoperatively even with the use of various diagnostic imaging modalities and histologic examination. As long as malignancy cannot be ruled out completely, surgery can be undertaken for the purposes of diagnosis and treatment. We report a case of unusual segmental stricture of the lower common bile duct mimicking bile duct cancer and discuss the differential diagnosis.

Mucin-producing bile duct tumor of the caudate lobe protruding into the common hepatic duct

Mucin-producing tumor in the bile duct is referred to clinically as mucin-producing bile duct tumor (MPBT). Intraductal papillary neoplasm of the biliary tract that resembles an intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a rare category of MPBT and is not well characterized. We, herein, report a case of MPBT of the caudate lobe of the liver that showed papillary growth and communicated with the bile duct of the caudate lobe and protruded into the common hepatic duct. Histologically, MPBT cells showed papillary overgrowth with abundant mucinous secretions, resembling an IPMN of the pancreas. The MPBT cells showed the same immunostaining pattern as that of cells from IPMN of the pancreas.

Tyrosine phosphorylation of β2-chimaerin by Src-family kinase negatively regulates its Rac-specific GAP activity

beta2-Chimaerin, an intracellular receptor for the second messenger diacylglycerol and phorbol esters, is a GTPase-activating protein (GAP) specific for Rac. beta2-Chimaerin negatively controls many Rac-dependent pathophysiological events including tumor development. However, the regulatory mechanism of beta2-chimaerin remains largely unknown. Here we report that beta2-chimaerin is tyrosine-phosphorylated by Src-family kinases (SFKs) upon cell stimulation with epidermal growth factor (EGF). Mutational analysis identified Tyr-21 in the N-terminal regulatory region as a major phosphorylation site. Intriguingly, the addition of SFK inhibitor and the replacement of Tyr-21 with Phe (Y21F) markedly enhanced Rac-GAP activity of beta2-chimaerin in EGF-treated cells. Moreover, the Y21F mutant inhibited integrin-dependent cell spreading, in which Rac1 plays a critical role, more strongly than wild-type beta2-chimaerin. These results suggest Tyr-21 phosphorylation as a novel, SFK-dependent mechanism that negatively regulates beta2-chimaerin Rac-GAP activity.

Vertical retrocolic duodenojejunostomy decreases delayed gastric emptying after pylorus-preserving pancreatoduodenectomy

BACKGROUND/AIMS

With the aim of preventing delayed gastric emptying (DGE) after pylorus-preserving pancreatoduodenectomy (PPPD), the new reconstruction method namely vertical retrocolic duodenojejunostomy in which the stomach and duodenum are brought down through the left side of the transverse mesocolon in a straight line thereby allowing these organs apart from the excised and anastomosed field and food passage by gravity is presented.

METHODOLOGY

The preoperative and intraoperative factors, and short-term outcomes with special reference to DGE were compared between the two groups, PPPD (n = 12) and standard pancreatoduodenectomy (PD, n = 9). PD was similarly carried out except for hemigastrectomy for comparison. DGE was defined as a need for nasogastric tube decompression for 10 days or more.

RESULTS

Preoperative and intraoperative factors were not significantly different between the two groups. DGE was absent in both groups because nasogastric tube was removed within 7 days in all patients with a mean of postoperative day 3 in both groups. The days until liquid diet in the PPPD group were similar, but those until regular diet were significantly faster compared with the PD group. Postoperative hospital stay was similar between the two groups.

CONCLUSIONS

The current reconstruction method may minimize DGE after PPPD.

A curative resection improves the postoperative survival rate even in patients with advanced gallbladder carcinoma

The aim of this study was to evaluate the results of our series of 90 operations for gallbladder carcinoma according to the Japanese Society of Biliary Surgery (JSBS) classification system and to clarify the appropriate surgical strategy for advanced gallbladder carcinoma based on the depth of primary tumor invasion and lymph node metastasis. Generally, only a surgical resection can achieve a prognostic improvement of the advanced gallbladder carcinoma. The survival of patients with this neoplasm depends strictly on the depth of histological primary tumor invasion and lymph node metastasis. A retrospective analysis was conducted on 90 patients from 1990 to 2004 who underwent a surgical resection of gallbladder carcinoma. The factors influencing survival were examined. Thirty-nine patients with palliative treatment (not resected cases), which was diagnosed as T3 or T4 by preoperative imagings, were also included in this study. The significance of the variables for survival was examined by the Kaplan-Meier method and the log-rank test followed by multivariate analyses using Cox's proportional hazard model. Portal invasion, lymph node metastasis, the surgical margin (+ vs. -) and the final curability (fCurA, B vs. C) were all found to be independent prognostic factors in the multivariate analysis. In pT2 gallbladder carcinoma, a better survival was achieved in an aggressive surgical approach, in order of a S4a+S5 hepatic resection, an extended cholecystectomy and a cholecystectomy. In pT3 and pT4, although radical extended surgery did not provide the opportunity for good survival even after lobectomy of the liver, the survival of patients with curative surgery was statistically better than in those without curative surgery. In addition, the nodal involvement of pN1 to pN2 was better than that with pN3. A S4a+S5 hepatectomy, therefore, appears to be adequate for the treatment of pT2 gallbladder carcinoma. Even in patients with pT3 and pT4 gallbladder carcinoma, long-term survival can be expected by an operation with a tumor-free surgical margin. The role of radical surgery, however, is considered to be limited in patients with pN3 lymph node metastasis.

Outcome of radical surgery for stage IV gallbladder carcinoma

BACKGROUND/PURPOSE

The role of aggressive surgery for patients with stage IV gallbladder carcinoma was examined.

METHODS

Cancers were classified according to the TNM system of the Japanese Society of Biliary Surgery. The survival of 37 patients with stage IV cancer (stage IVa, n = 15; stage IVb, n = 22) treated by surgical resection during the period January 1990 to December 2004 was examined and compared with the survival of 41 patients with stage IV disease not treated by surgical resection during the same period.

RESULTS

The postoperative survival rate was significantly better for patients with resected stage IVa cancer than for patients with resected stage IVb disease and for those with nonresected stage IV disease. Survival in patients with N3 lymph node metastasis, liver metastasis, peritoneal dissemination, or vascular invasion was poor, like that in the nonresected group. Surgical resection without residual tumors (curability A and B) yielded a significantly better outcome than that with residual tumor (curability C). There were three 5-year survivors that were treated successfully by curative resection (curability A and B) and all had T4N0 disease.

CONCLUSIONS

These results suggest that surgical resection significantly improves survival even in patients with stage IV gallbladder carcinoma when N3 metastasis, liver metastasis, peritoneal dissemination, and vascular invasion are absent. Curative resection can be expected to produce long-term survival in selected patients with stage IV gallbladder carcinoma.

Comparison of seven prognostic staging systems in patients who undergo hepatectomy for hepatocellular carcinoma

BACKGROUND/AIMS

Various staging systems containing both the tumor and liver function factors for hepatocellular carcinoma (HCC) have been proposed. The aim of this study was to evaluate the appropriate staging system in patients received hepatic resection for HCC.

METHODOLOGY

The prognosis of the 235 patients who had undergone hepatectomy in these 15 years were analyzed according to the 7 staging systems, the Cancer of the Liver Italian Program (CLIP) score, the Barcelona Clinic Liver Cancer (BCLC) staging, the Groupe d'Etude et de Traitment du Carcinome Hépatocellulaire (GETCH) classification, the Chinese University Prognostic Index (CUPI) grade, the Japan Integrated Staging (JIS) score, modified JIS (mJIS) score, and Tokyo score. The capabilities to differentiate the postoperative survival between the neighboring score in each staging system were examined. Statistical analyses of the log-rank test, linear trend test, likelihood ratio (LR) test, Akaike Information Criteria (AIC), and Harrels' c-index were used.

RESULTS

The patients were widely distributed in the most of the staging system with the exceptions of GETCH classification and CUPI grade where almost all patients were classified to only the two groups. CLIP, JIS, mJIS, and Tokyo scores significantly differentiated the postoperative survival rate between 2 or 3 neighboring scores, whereas other staging systems only did between one. Statistical evaluations of prognostic stratification by the LR test, AIC, and Harrels' c-index showed that the JIS score system was the best among the 7 staging systems.

CONCLUSIONS

JIS score is the best staging system for HCC in patients who undergo hepatectomy.

Diacylglycerol kinases: Why so many of them?

Diacylglycerol (DAG) kinase (DGK) modulates the balance between the two signaling lipids, DAG and phosphatidic acid (PA), by phosphorylating DAG to yield PA. To date, ten mammalian DGK isozymes have been identified. In addition to the C1 domains (protein kinase C-like zinc finger structures) conserved commonly in all DGKs, these isoforms possess a variety of regulatory domains of known and/or predicted functions, such as a pair of EF-hand motifs, a pleckstrin homology domain, a sterile alpha motif domain and ankyrin repeats. Beyond our expectations, recent studies have revealed that DGK isozymes play pivotal roles in a wide variety of signal transduction pathways conducting development, neural and immune responses, cytoskeleton reorganization and carcinogenesis. Moreover, there has been rapidly growing evidence indicating that individual DGK isoforms exert their specific roles through interactions with unique partner proteins such as protein kinase Cs, Ras guanyl nucleotide-releasing protein, chimaerins and phosphatidylinositol-4-phosphate 5-kinase. Therefore, an emerging paradigm for DGK is that the individual DGK isoforms assembled in their own signaling complexes should carry out spatio-temporally segregated tasks for a wide range of biological processes via regulating local, but not global, concentrations of DAG and/or PA.

Diacylglycerol kinase α suppresses tumor necrosis factor-α-induced apoptosis of human melanoma cells through NF-κB activation

We investigated the implication of diacylglycerol kinase (DGK) alpha (type I isoform) in melanoma cells because we found that this DGK isoform was expressed in several human melanoma cell lines but not in noncancerous melanocytes. Intriguingly, the overexpression of wild-type (WT) DGKalpha, but not of its kinase-dead (KD) mutant, markedly suppressed tumor necrosis factor (TNF)-alpha-induced apoptosis of AKI human melanoma cells. In the reverse experiment, siRNA-mediated knockdown of DGKalpha significantly enhanced the apoptosis. The overexpression of other type I isoforms (DGKbeta and DGKgamma) had, on the other hand, no detectable effects on the apoptosis. These results indicate that DGKalpha specifically suppresses the TNF-alpha-induced apoptosis through its catalytic action. We found that the overexpression of DGKalpha-WT, but not of DGKalpha-KD, further enhanced the TNF-alpha-stimulated transcriptional activity of an anti-apoptotic factor, NF-kappaB. Conversely, DGKalpha-knockdown considerably inhibited the NF-kappaB activity. Moreover, an NF-kappaB inhibitor blunted the anti-apoptotic effect of DGKalpha overexpression. Together, these results strongly suggest that DGKalpha is a novel positive regulator of NF-kappaB, which suppresses TNF-alpha-induced melanoma cell apoptosis.

Segmentectomy for reactive lymphoid hyperplasia of the liver: Report of a case

We report a case of reactive lymphoid hyperplasia (RLH) of the liver in a 72-year-old woman without any symptoms. To our knowledge, only 11 other cases of this disease have ever been reported. The lesion was found incidentally during a medical examination, as a hypoechoic mass in segment 3 of the liver on ultrasonography. The findings of computed tomography, magnetic resonance imaging, and angiography suggested a malignancy. Frozen section diagnosis of an intraoperative needle biopsy suggested malignant lymphoma, so we performed lateral segmentectomy of the liver. Macroscopically, the tumor was well defined, white, and firm. Microscopically, there was polymorphous lymphoplasmacytic infiltration, with various-sized and -shaped lymphoid follicles. Lymphocytic infiltration was also observed in the portal tracts around the nodular lesion. Immunohistochemical study revealed polyclonality, confirming a pathological diagnosis of RLH of the liver. We discuss the clinicopathologic characteristics of this unusual disease.

Diacylglycerol kinase γ interacts with and activates β2-chimaerin, a Rac-specific GAP, in response to epidermal growth factor

Diacylglycerol kinase (DGK)gamma was shown to act as an upstream suppressor of Rac1. Here we report that, in COS7 cells stimulated with epidermal growth factor (EGF), DGKgamma specifically interacts and co-localizes at the plasma membrane with beta2-chimaerin, a GTPase-activating protein (GAP) for Rac. Moreover, DGKgamma enhanced EGF-dependent translocation of beta2-chimaerin to the plasma membrane. Interestingly, DGKgamma markedly augmented EGF-dependent GAP activity of beta2-chimaerin through its catalytic action. These results indicate that DGKgamma is a novel regulator of beta2-chimaerin, and thus suggest that beta2-chimaerin is an effector molecule, linking DGKgamma functionally with Rac1.

Lipid Phosphate Phosphatases 1 and 3 Are Localized in Distinct Lipid Rafts

Lipid phosphate phosphatases (LPPs), integral membrane proteins with six transmembrane domains, dephosphorylate a variety of extracellular lipid phosphates. Although LPP3 is already known to bind to Triton X-100-insoluble rafts, we here report that LPP1 is also associated with lipid rafts distinct from those harboring LPP3. We found that LPP1 was Triton X-100-soluble, but CHAPS-insoluble in LNCaP cells endogenously expressing LPP1 and several LPP1 cDNA-transfected cells including NIH3T3 fibroblasts. In addition to the non-ionic detergent insolubility, LPP1 further possessed several properties formulated for raft-localizing proteins as follows: first, the CHAPS-insolubility was resistant to the actin-disrupting drug cytochalasin D; second, the CHAPS-insoluble LPP1 floated in an Optiprep density gradient; third, the CHAPS insolubility of LPP1 was lost by cholesterol depletion; and finally, the subcellular distribution pattern of LPP1 exclusively overlapped with that of a raft marker, cholera toxin B subunit. Interestingly, confocal microscopic analysis showed that LPP1 was distributed to membrane compartments distinct from those of LPP3. Analysis using various LPP1/LPP3 chimeras revealed that their first extracellular regions determine the different Triton X-100 solubilities. These results indicate that LPP1 and LPP3 are distributed in distinct lipid rafts that may provide unique microenvironments defining their non-redundant physiological functions.

Effects of bezafibrate in patients with chronic hepatitis C virus infection: combination with interferon and ribavirin

An association of hepatitis C virus (HCV) with low-density lipoproteins (LDL) in serum of patients with chronic hepatitis C (CHC) has been suggested. We conducted a prospective study in CHC patients complicated with hyperlipidaemia, to examine whether bezafibrate, which is commonly used for treatment of hyperlipidaemia, reduces serum HCV-RNA titre and improves liver dysfunction. Fifteen patients received daily oral bezafibrate treatment (400 mg/day) for 8 weeks, and its effects on serum lipids, transaminases, HCV-RNA titres, and HCV-RNA titres bound to LDL were evaluated. Fifteen untreated patients with CHC and hyperlipidaemia were used as controls. The mean serum alanine aminotransferase levels and HCV-RNA titres significantly decreased at the end of bezafibrate therapy in the treated group (105 +/- 34 to 80 +/- 32 IU/L, P = 0.02 and 2.23 +/- 2.71 to 1.78 +/- 2.38 x 10(7) copies/mL, P < 0.01 respectively), but no changes were observed in the control group. Serum HCV-RNA titres bound to LDL, as quantified by immunoprecipitation using anti-LDL antibody, also decreased in all 15 treated patients [5.55 +/- 6.59 to 1.07 +/- 1.58 x 10(6) copies/ml, P < 0.01 (mean reduction rate was -78.5 +/- 17.0%)]. Sucrose density-gradient ultracentrifugation study revealed that HCV-RNA-decreased density fractions after the bezafibrate were identical to LDL-density fractions (1.015-1.062 g/mL). Eight CHC patients were treated with bezafibrate, interferon, and ribavirin triple therapy for 32 weeks, and four patients achieved sustained virological response to therapy. This pilot study provides further evidence of an association between HCV and LDL in serum and suggests the potential usefulness of bezafibrate as an anti-HCV reagent for the treatment of CHC patients.

Risk factors for early death after liver resection in patients with solitary hepatocellular carcinoma

BACKGROUND/PURPOSE

Although most patients who receive hepatectomy for a solitary hepatocellular carcinoma (HCC) have a relatively fair result, some have a poor prognosis. The aim of this study was to evaluate the risk factors for early death after hepatectomy in patients with a solitary HCC.

METHODS

Eligible patients (n=110) who had undergone hepatectomy for solitary HCC between 1990 and 2002 and were able to be followed up for more than 2 years after the hepatectomy were divided into two groups, those who died of cancer recurrence within 2 years (early-death group; n=18) and those who survived for more than 2 years after the surgery (survival group; n=92). Risk factors for early death after liver resection were evaluated by univariate and multivariate analyses.

RESULTS

The gross tumor classification, tumor diameter, macroscopic portal vein invasion, microscopic growth pattern, microscopic vascular invasion (MVI), and the width of the surgical margin were significant (P<0.05) factors by univariate analysis. Multivariate analysis showed that the presence of MVI was an independent and significant risk factor for early death of recurrence.

CONCLUSIONS

Among patients with solitary HCC, the presence of MVI indicates a poor prognosis. These patients need adjuvant chemotherapy in the early period after hepatectomy.

Nuclear Transportation of Diacylglycerol Kinase γ and Its Possible Function in the Nucleus

Diacylglycerol kinases (DGKs) convert diacylglycerol (DG) to phosphatidic acid, and both lipids are known to play important roles in lipid signal transduction. Thereby, DGKs are considered to be a one of the key players in lipid signaling, but its physiological function remains to be solved. In an effort to investigate one of nine subtypes, we found that DGKgamma came to be localized in the nucleus with time in all cell lines tested while seen only in the cytoplasm at the early stage of culture, indicating that DGKgamma is transported from the cytoplasm to the nucleus. The nuclear transportation of DGKgamma didn't necessarily need DGK activity, but its C1 domain was indispensable, suggesting that the C1 domain of DGKgamma acts as a nuclear transport signal. Furthermore, to address the function of DGKgamma in the nucleus, we produced stable cell lines of wild-type DGKgamma and mutants, including kinase negative, and investigated their cell size, growth rate, and cell cycle. The cells expressing the kinase-negative mutant of DGKgamma were larger in size and showed slower growth rate, and the S phase of the cells was extended. These findings implicate that nuclear DGKgamma regulates cell cycle.

Identification and characterization of a novel human type II diacylglycerol kinase, DGK kappa

Diacylglycerol kinase (DGK) plays an important role in signal transduction through modulating the balance between two signaling lipids, diacylglycerol and phosphatidic acid. Here we identified a tenth member of the DGK family designated DGK kappa. The kappa-isozyme (1271 amino acids, calculated molecular mass, 142 kDa) contains a pleckstrin homology domain, two cysteine-rich zinc finger-like structures, and a separated catalytic region as have been found commonly for the type II isozymes previously cloned (DGKdelta and DGKeta). The new DGK isozyme has additionally 33 tandem repeats of Glu-Pro-Ala-Pro at the N terminus. Reverse transcriptase-PCR showed that the DGK kappa mRNA is most abundant in the testis, and to a lesser extent in the placenta. DGK kappa, when expressed in HEK293 cells, was persistently localized at the plasma membrane even in the absence of cell stimuli. Deletion analysis revealed that the short C-terminal sequence (amino acid residues 1199-1268) is necessary and sufficient for the plasma membrane localization. Interestingly, DGK kappa, but not other type II DGKs, was specifically tyrosine-phosphorylated at Tyr78 through the Src family kinase pathway in H2O2-treated cells. Moreover, H2O2 selectively inhibited DGK kappa activity in a Src family kinase-independent manner, suggesting that the isozyme changes the balance of signaling lipids in the plasma membrane in response to oxidative stress. The expression patterns, subcellular distribution, and regulatory mechanisms of DGK kappa are distinct from those of DGKdelta and DGKeta despite high structural similarity, suggesting unique functions of the individual type II isozymes.

Comparison of a digital flat-panel versus screen–film, photofluorography and storage-phosphor systems by detection of simulated lung adenocarcinoma lesions using hard copy images

The purpose of this study was to compare hard copy images from a flat-panel detector digital radiography system with conventional radiography, photofluorographic radiography and storage phosphor radiography for the detection of simulated lung adenocarcinoma lesions and also for radiation dose. To test the diagnostic performance of these four systems, the authors used 15 types of lung adenocarcinoma phantom according to Noguchi's classification and an anthropomorphic chest phantom. The visual evaluation of tumour detectability by four radiologists and two general thoracic surgeons was examined with a five-level confidence scale. Lung doses were measured with glass dosemeters for the chest radiology systems under the conditions used by each hospital and centre. Our results indicated that flat-panel detector digital radiography and storage phosphor radiography are not necessarily superior to conventional radiography and photofluorographic radiography for detecting lung adenocarcinomas when only hard copy images are used, and this suggests a need to carefully optimize chest radiography.

Prognostic benefit of selective portal vein occlusion during hepatic resection for hepatocellular carcinoma

BACKGROUND

The aim of this study was to clarify whether the types of portal vein (PV) occlusion during hepatectomy affect the long-term outcome in patients with hepatocellular carcinoma (HCC).

METHODS

Eighty-six patients who had undergone curative hepatic resection for HCC were divided on the basis of the type of PV occlusion into 2 groups: total PV occlusion (TPVO, n = 56) and selective PV occlusion (SPVO, n = 30) groups. The recurrence-free survival was compared between the groups, and factors affecting recurrence-free survival were examined by univariate analyses followed by multivariate analyses. Moreover, the patients with a single nodular HCC less than 5 cm in diameter were abstracted from both groups, and the recurrence-free survival rate was compared.

RESULTS

The patients and tumor-related factors were similar in the TPVO and SPVO groups. The recurrence-free survival was better in the SPVO group than in the TPVO group (median recurrence-free survival time, 1520 vs 561 days, P = .017). The type of PV occlusion was a significant factor for recurrence-free survival by univariate analysis but did not reach significance ( P = .052) by multivariate analysis. In the selected patients who had a single nodular HCC less than 5 cm in diameter, the recurrence-free survival was also significantly better in the SPVO group than in the TPVO group (median recurrence-free survival time, 2613 vs 1003 days, P = .018).

CONCLUSIONS

Hepatectomy under selective PV occlusion seems to improve the recurrence-free survival in patients with HCC.

The plasma membrane translocation of diacylglycerol kinase delta1 is negatively regulated by conventional protein kinase C-dependent phosphorylation at Ser-22 and Ser-26 within the pleckstrin homology domain

DGK (diacylglycerol kinase) regulates the concentration of two bioactive lipids, diacylglycerol and phosphatidic acid. DGKdelta1 or its PH (pleckstrin homology) domain alone has been shown to be translocated to the plasma membrane from the cytoplasm in PMA-treated cells. In the present study, we identified Ser-22 and Ser-26 within the PH domain as the PMA- and epidermal-growth-factor-dependent phosphorylation sites of DGKdelta1. Experiments in vitro and with intact cells suggested that the cPKC (conventional protein kinase C) phosphorylated these Ser residues directly. Puzzlingly, alanine/asparagine mutants at Ser-22 and Ser-26 of DGKdelta1 and its PH domain are still persistently translocated by PMA treatment, suggesting that the PH domain phosphorylation is not responsible for the enzyme translocation and that the translocation was caused by a PMA-dependent, but cPKC-independent, process yet to be identified. Interestingly, the aspartate mutation, which mimics phosphoserine, at Ser-22 or Ser-26, inhibited the translocation of full-length DGKdelta1 and the PH domain markedly, suggesting that the phosphorylation regulates negatively the enzyme translocation. Our results provide evidence of the phosphorylation of the DGKdelta1 PH domain by cPKC, and suggest that the phosphorylation is involved in the control of subcellular localization of DGKdelta1.

Heparin-binding EGF-like growth factor is a promising target for ovarian cancer therapy

Ovarian cancer is the most frequent cause of cancer death among all gynecologic cancers. We demonstrate here that lysophosphatidic acid (LPA)-induced ectodomain shedding of heparin-binding EGF-like growth factor (HB-EGF) is a critical to tumor formation in ovarian cancer. We found that among the epidermal growth factor receptor (EGFR) family of growth factors, HB-EGF gene expression in cancerous tissues and HB-EGF protein levels in patients' ascites fluid were significantly elevated. The human ovarian cancer cell lines SKOV3 and RMG-1 form tumors in nude mice. Tumor formation of these cells was enhanced by exogenous expression of pro-HB-EGF and completely blocked by pro-HB-EGF gene RNA interference or by CRM197, a specific HB-EGF inhibitor. Transfection with mutant forms of HB-EGF indicated that the release of soluble HB-EGF is essential for tumor formation. LPA, which is constitutively produced by ovarian cancer cells, induced HB-EGF ectodomain shedding in SKOV3 and RMG-1 cells, resulting in the transactivation of EGFR and the downstream kinase extracellular signal-regulated kinase/mitogen-activated protein kinase. LPA-induced transactivation was abrogated by HB-EGF gene RNA interference or by CRM197. Introduction of lipid phosphate phosphohydrolase, which hydrolyzes LPA, decreased the constitutive shedding of HB-EGF, EGFR transactivation, and the tumorigenic potential of SKOV3 and RMG-1 cells. These results indicate that HB-EGF is the primary member of the EGFR family of growth factors expressed in ovarian cancer and that LPA-induced ectodomain shedding of this growth factor is a critical step in tumor formation, making HB-EGF a novel therapeutic target for ovarian cancer.

Diacylglycerol Kinase γ Serves as an Upstream Suppressor of Rac1 and Lamellipodium Formation

Nine diacylglycerol kinase (DGK) isozymes have been identified. However, our knowledge of their individual functions is still limited. Here, we demonstrate the role of DGKgamma in regulating Rac1-governed cell morphology. We found that the expression of kinase-dead DGKgamma, which acts as a dominant-negative mutant, and inhibition of endogenous DGKgamma activity with R59949 induced lamellipodium and membrane ruffle formation in NIH3T3 fibroblasts in the absence of growth factor stimulation. Reciprocally, lamellipodium formation induced by platelet-derived growth factor was significantly inhibited upon expression of constitutively active DGKgamma. Moreover, the constitutively active DGKgamma mutant suppressed integrin-mediated cell spreading. These effects are isoform-specific because, in the same experiments, none of the corresponding mutants of DGKalpha and DGKbeta, closely related isoforms, affected cell morphology. These results suggest that DGKgamma specifically participates in the Rac1-mediated signaling pathway leading to cytoskeletal reorganization. In support of this, DGKgamma co-localized with dominant-active Rac1 especially in lamellipodia. Moreover, we found that endogenous DGKgamma was physically associated with cellular Rac1. Dominant-negative Rac1 expression blocked the lamellipodium formation induced by kinase-dead DGKgamma, indicating that DGKgamma acts upstream of Rac1. This model is supported by studies demonstrating that kinase-dead DGKgamma selectively activated Rac1, but not Cdc42. Taken together, these results strongly suggest that DGKgamma functions through its catalytic action as an upstream suppressor of Rac1 and, consequently, lamellipodium/ruffle formation.

A single administration of interleukin-4 antagonistic mutant DNA inhibits allergic airway inflammation in a mouse model of asthma

Interleukin 4 (IL-4) is essential for the switching of B cells to IgE antibody production and for the maturation of T helper (Th) cells toward the Th2 phenotype. These mechanisms are thought to play a crucial role in the pathogenesis of the allergic airway inflammation observed in asthma. In the present study, we examined the anti-inflammatory effects of DNA administration of murine IL-4 mutant Q116D/Y119D (IL-4 double mutant, IL-4DM), which binds to the IL-4 receptor alpha and is an antagonist for IL-4. Immunization of BALB/c mice with alum-adsorbed ovalbumin (OVA) followed by aspiration with aerosolized OVA resulted in the development of allergic airway inflammation. A single administration of IL-4DM DNA before the aerosolized OVA challenge protected the mice from the subsequent induction of allergic airway inflammation. Serum IgE level and extent of eosinophil infiltration in bronchoalveolar lavage (BAL) from IL-4DM DNA-administered mice were significantly lower than those in BAL from control plasmid-immunized mice. In our study, IL-4 or IL-4 mutants were not detected in sera from mice that had received a single administration of IL-4DM DNA. The results of this study provide evidence for the potential utility of IL-4 mutant antagonist DNA inoculation as an approach to gene therapy for asthma.

Sex differences due to dehydroepiandrosterone (DHEA) feeding affecting dehydroepiandrosterone sulfate secretion in golden Syrian hamsters

The metabolism of orally administered dehydroepiandrosterone (DHEA) by male and female golden Syrian hamsters was examined by quantification of DHEA and dehydroepiandrosterone sulfate (DHEAS) in gallbladder bile, urine and feces using high-performance liquid chromatography (HPLC). Plasma levels of DHEA and DHEAS were also determined by radioimmunoassay (RIA). After 5 days of oral DHEA administration (100 mg/kg body weight twice a day), RIA showed that plasma levels of DHEA and DHEAS were increased approximately 3-6 and 4-5 times, respectively, compared to controls. More than 95 % of circulating DHEA (S) in the peripheral blood was DHEAS. There was no significant sex difference in DHEAS plasma levels between male and female animals in the DHEA-supplemented group. However, 0.2 - 0.3 % of ingested DHEA was conjugated to DHEAS and excreted in urine by females, whereas less than 0.002 % was excreted in urine by males (p < 0.005). DHEAS was excreted in bile by males after DHEA supplementation, and the sex differences in DHEAS levels observed in bile were statistically significant (male, 18.7 +/- 7.5 vs. female, 5.6 +/- 3.1 micromol/l) (p < 0.005). Small amounts of ingested DHEA were excreted in an unchanged state in feces, and no sex difference was observed. These results suggest that there is a considerable sex difference in the conjugation and excretion of orally administered DHEA in the hamster.

Differential localization of lipid phosphate phosphatases 1 and 3 to cell surface subdomains in polarized MDCK cells

Lipid phosphate phosphatases (LPPs) are integral membrane proteins with six transmembrane domains that act as ecto-enzymes dephosphorylating a variety of extracellular lipid phosphates. Using polarized MDCK cells stably expressing human LPP1 and LPP3, we found that LPP1 was located exclusively at the apical surface whereas LPP3 was distributed mostly in the basolateral subdomain. We identified a novel apical sorting signal at the N-terminus of LPP1 composed of F(2)DKTRL(7). In the case of LPP3, a dityrosine motif present in the second cytoplasmic portion was identified as basolateral targeting signal. Our work shows that LPP1 and LPP3 are equipped with distinct sorting signals that cause them to differentially localize to the apical vs. the basolateral subdomain, respectively.

Preparation of platinum(II) complexes with l-serine using KI. X-ray crystal structure, HPLC and 195Pt NMR spectra

The preparation of platinum(II) complexes containing L-serine using K(2)[PtCl(4)] and KI as raw materials was undertaken. The cis-trans isomer ratio of the complexes in the reaction mixture differed significantly depending on whether KI was present or absent in the reaction mixture. One of the two [Pt(L-ser-N,O)(2)] complexes (L-ser=L-serinate anion) prepared using KI crystallizes in the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions a=8.710(2) A, b=9.773(3) A, c=11.355(3) A, Z=4. The crystal data revealed that this complex has a cis configuration. The other [Pt(L-ser-N,O)(2)] complex also crystallizes in the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions a=7.0190(9) A, b=7.7445(6) A, c=20.946(2) A, Z=4. The crystal data revealed that this complex has a trans configuration. The 195Pt NMR chemical shifts of trans-[Pt(L-ser-N,O)(2)] and cis-[Pt(L-ser-N,O)(2)] complexes are -1632 and -1832 ppm, respectively. 195Pt NMR and HPLC measurements were conducted to monitor the reactions of the two [Pt(L-ser-N,O)(2)] complexes with HCl. Both 195Pt NMR and HPLC showed that the reactivities of cis- and trans-[Pt(L-ser-N,O)(2)] toward HCl are different: coordinated carboxyl oxygen atoms of trans-[Pt(L-ser-N,O)(2)] were detached faster than those for cis-[Pt(L-ser-N,O)(2)].