Increased insulin demand promotes while pioglitazone prevents pancreatic beta cell apoptosis in Wfs1 knockout mice

AIMS/HYPOTHESIS

The WFS1 gene encodes an endoplasmic reticulum (ER) membrane-embedded protein called Wolfram syndrome 1 protein, homozygous mutations of which cause selective beta cell loss in humans. The function(s) of this protein and the mechanism by which the mutations of this gene cause beta cell death are still not fully understood. We hypothesised that increased insulin demand as a result of obesity/insulin resistance causes ER stress in pancreatic beta cells, thereby promoting beta cell death.

METHODS

We studied the effect of breeding Wfs1 ( -/- ) mice on a C57BL/6J background with mild obesity and insulin resistance, by introducing the agouti lethal yellow mutation (A ( y ) /a). We also treated the mice with pioglitazone.

RESULTS

Wfs1 ( -/- ) mice bred on a C57BL/6J background rarely develop overt diabetes by 24 weeks of age, showing only mild beta cell loss. However, Wfs1 ( -/- ) A ( y ) /a mice developed selective beta cell loss and severe insulin-deficient diabetes as early as 8 weeks. This beta cell loss was due to apoptosis. In Wfs1 ( +/+ ) A ( y ) /a islets, levels of ER chaperone immunoglobulin-binding protein (BiP)/78 kDa glucose-regulated protein (GRP78) and phosphorylation of eukaryotic translation initiation factor 2, subunit alpha (eIF2alpha) apparently increased. Levels of both were further increased in Wfs1 ( -/- ) A ( y ) /a murine islets. Electron micrography revealed markedly dilated ERs in Wfs1 (-/-) A ( y ) /a murine beta cells. Interestingly, pioglitazone treatment protected beta cells from apoptosis and almost completely prevented diabetes development.

CONCLUSIONS/INTERPRETATION

Wfs1-deficient beta cells are susceptible to ER stress. Increased insulin demand prompts apoptosis in such cells in vivo. Pioglitazone, remarkably, suppresses this process and prevents diabetes. As common WFS1 gene variants have recently been shown to confer a risk of type 2 diabetes, our findings may be relevant to the gradual but progressive loss of beta cells in type 2 diabetes.

HER2 and HER3 cooperatively regulate tumor cell growth and determine sensitivity to the HER kinase inhibitor TAK-285

Abstract #3155

Background: The HER (ErbB) receptor family plays a major role in the proliferation of tumor cells. Overexpression of these receptors occurs in breast and a variety of cancers and correlates with poor prognosis. We have identified TAK-285, a potent, selective and orally bioavailable small molecule inhibitor of HER kinases. TAK-285, which is currently in clinical trials for the treatment of solid tumors, inhibits EGFR (also known as ErbB1 or HER1) and HER2 (also known as ErbB2) and exerts clear anti-proliferative activity in in vitro and in vivo tumor models. Here, we elucidated the determinants of TAK-285 anti-tumor activity in vitro in a panel of human cancer cell lines.
 Methods: Cell growth inhibition assay was performed using sulforodamine B staining method or CellTiter-GloTM assay (Promega). Candidate gene expressions were measured by quantitative PCR. Associations between the IC50 values and the candidate gene expressions were statistically analysed.
 Results: TAK-285 exerted anti-proliferative effects in all of cell lines tested in a dose dependent manner but the effects ranged widely (IC50: 0.011-over 10 µmol/L). Statistical analysis showed an inverse correlation between sensitivity to TAK-285 (IC50 values) and HER2 or HER3 (also known as ErbB3) gene expression. PTEN or IGF-1R gene expression, reported to be involved in trastuzumab resistance, was not correlated with TAK-285 sensitivity. Immunoblot analysis revealed that HER2 and HER3 are coexpressed in most TAK-285 sensitive cells and TAK-285 inhibited phosphorylation of HER3. Because HER3 does not possess kinase activity, this suggests that HER3 is trans-phosphorylated by HER2. Knockdown of HER3 using siRNA inhibited tumor cell growth in TAK-285 sensitive cells but not in TAK-285 insensitive cells.
 Conclusion: These results suggest that HER2 and HER3 mainly regulate tumor cell growth in TAK-285 sensitive cells and could be used as a molecular marker to select patients who are likely to respond to TAK-285.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3155.

A novel HER2 inhibitor TAK-285 overcomes trastuzumab resistance of HER2-over-expressing breast cancer

Abstract #3143

Background: The anti-HER2 antibody trastuzumab has been proven highly effective in the treatment of HER2-expressing breast cancers clinically. However, the continuous administration often leads to drug resistance, the mechanism of which is not well understood. Here we present a new mechanism for trastuzumab-resistance. We also show TAK-285, a novel small molecule HER2/EGFR kinase inhibitor under clinical evaluation, overcomes the resistance to trastuzumab.
 Methods: A trastuzumab-resistant sub-clone (BT-474TR) of the HER2-positive human breast cancer line, BT-474, was established in house by serial passage in the presence of 5 μg/mL trastuzumab for over 5 months. Gene expression profiles of the clones were assessed using Affymetrix HG-U133 plus 2.0 human gene arrays and confirmed by real-time PCR. Target genes were depleted by siRNA-mediated knockdown and confirmed by real time-PCR and immunoblot. Effects on cell growth were assessed by the CellTiter-Glo luminescent cell viability assay (Promega).
 Results: BT-474TR cells exhibited modified expression of several genes including cofilin, compared to the parental BT-474 cells. Although immunoblotting using anti-cofilin antibody revealed no clear change in protein level, BT-474TR displayed significant increase in phosphorylation of cofilin. Gene-specific knockdown of cofilin-1 led to re-sensitization of BT-474TR to trastuzumab, though the cofilin-2 knockdown did not. Likewise, knockdown of either LIMK1 or PAK1, known to regulate cofilin-phosphorylation, resulted in similar re-sensitization of BT-474TR to trastuzumab. BT-474TR also exhibited increase in phosphorylation of both LIMK1 and PAK1. TAK-285 showed almost equivalent inhibitory activity against both BT-474 and BT-474TR proliferation in cell culture and in xenograft study, while trastuzumab did not affect the proliferation of BT-474TR in either condition
 Conclusions: These data suggest that activation of cofilin signaling pathway is a probable mechanism of trastuzumab resistance. PAK1/LIMK1/cofilin-1 inhibitors might therefore be useful in preventing or reversing trastuzumab resistance. The phosphorylation status of PAK1/LIMK1/cofilin might also serve as a biomarker of Trastuzumab-sensitivity. Moreover a novel HER2 inhibitor, TAK-285, might show benefit in the treatment of trastuzumab-resistant HER2-expressing breast cancers.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3143.

A prototype model using clinical document architecture (CDA) with a Japanese local standard : designing and implementing a referral letter system

Since clinical document architecture (CDA) became an American National Standards Institute (ANSI)-approved health level seven (HL7) Standard, many countries have begun making an effort to make local standards conform to CDA. In order to make CDA compatible with the many different local standards existing in different countries, we designed a prototype model using HL7 CDA R2 with medical markup language (MML), a Japanese medical data exchange standard. Furthermore, a referral letter system based on this model was developed. Archetypes were used to express medical concepts in a formal manner and to make 2 different standards work collaboratively. We share herein the experience gathered in designing and implementing a referral letter system based on HL7 CDA, Release 2 (CDA R2). We also outline the challenges encountered in our project and the opportunities to widen the scope of this approach to other clinical documents.

A two-degree-of-freedom motor-powered gait orthosis for spinal cord injury patients

A number of orthoses have been developed to restore stance and walking in paraplegic subjects. Compliance, however, has been limited, mainly owing to walking effort. Use of the forces produced by actuators is an effective way to solve the problem of the considerable effort required for orthotic gait, namely high muscular effort and high energy expenditure. The purpose of the present study was to investigate the effects of assistance by external actuators on the orthotic gait of spinal cord injury (SCI) patients. Two kinds of linear actuator were developed by using direct current (d.c.) motors for assisting the knee and hip joint of a gait orthosis. They were mounted on the knee and hip joint of a commercial advanced reciprocating gait orthosis (ARGO), and a new two-degree-of-freedom externally powered gait orthosis was thus developed. The orthosis was assessed through inter-subject experiments on five male adult complete SCI patients. Owing to the short training period available for the assisted gait, simultaneous operation of both joint actuators was not conducted: either the knee actuation or the hip actuation was executed only. Thus, the knee actuator and the hip actuator were assessed with a T12 subject and with subjects for T5, T8, T11, and T12 respectively. The motions of the gaits, assisted by the linear actuators, were measured by a Vicon 370 system, and the general gait parameters and compensatory motions were evaluated. Results demonstrated that (a) all subjects could walk without falling, assisted either by the knee or the hip actuator; (b) both the knee and hip joint actuator increased the gait speed and the step length; (c) the knee flexion produced by the orthosis improved the dynamic cosmesis of walking; and (d) lateral compensatory motions as well as vertical ones tended to decrease when the hip joint was assisted, which could contribute to a reduction in walking effort.

Predicting recurrence following curative surgery in stage I non-small cell lung cancer patients using an angiogenesis-associated factor

There are still difficulties in determining the risk of recurrence to decide whether to perform selective adjuvant treatment for stage I non-small cell lung cancer. This study reviewed 122 stage I patients who underwent curative surgery to assess the usefulness of an angiogenesis-associated factor as a predictor of recurrence. By immunohistochemical examination, we collected information about tumor-induced vascular endothelial growth factor (VEGF)-A and -C expression at the primary site. During the median follow-up period of 120 months, the overall 10-year survival rate was 53.5%. The 10-year survival rates according to VEGF-A/C expression were as follows: VEGF-A high/VEGF-C high group, 26.0%; VEGF-A high/VEGF-C low group, 42.7%; VEGF-A low/VEGF-C high group, 73.1%; VEGF-A low/VEGF-C low group, 65.1%. The VEGF-A high/VEGF-C high group showed the worst outcome. The diagnostic values of the marker combination for predicting recurrence were as follows: sensitivity, 71.4%; specificity, 63.8%; and accuracy, 65.6%. When stratified by T factor, preferable high values for both negative predictive value and specificity were obtained in patients with stage IA disease. In order to select the patients eligible for selective adjuvant therapy at early stages, especially in stage IA disease, simultaneous assessment of tumor-induced VEGF-A/C warrants further study.

In vivo experimental model of human gingival mucosa using immunodeficient mice

BACKGROUND AND OBJECTIVE

To establish an in vivo experimental model for examining human periodontal tissue, the present study examined several transplant techniques that maintain the structure and characteristics of human gingival mucosa.

MATERIAL AND METHODS

Human oral mucosal tissue samples were collected from the gingiva (n = 11), palate (n = 1), and tongue (n = 3). These mucosal grafts were transplanted onto BALB/c nu/scid mice with double-mutant immunodeficiency. Murine skin, twice the size of the graft, was cut open in an ' square superset'-shape. Next, the connective tissue side of the graft was placed onto the murine connective tissue. Immunohistochemical analysis was also performed, using polyclonal rabbit antibody to involucrin, monoclonal antibody to vimentin, monoclonal antibody to CD34, and monoclonal antibody to Ki-67, to determine whether the characteristics of human oral mucosa were maintained.

RESULTS

When the connective tissue side of the graft was placed on the murine fascial membrane, the histological structure of the graft was maintained for 60 d. These grafts were examined for human characteristics using human-specific antibodies. Immunohistochemically, the expression patterns of involucrin, vimentin, and Ki-67 indicated that transplanted mucosa revealed normal human characteristics, including differentiation and proliferation up to 80 d. CD34 was not detected in the graft endothelial cells.

CONCLUSION

The present study revealed that the novel technique of transplantation of human gingival mucosa in nu/scid mice may serve as an in vivo experimental model of periodontal disease.

Ascorbic acid deficiency aggravates stress-induced gastric mucosal lesions in genetically scorbutic ODS rats

We examined whether ascorbic acid (AA) deficiency aggravates water immersion restraint stress (WIRS)-induced gastric mucosal lesions in genetically scorbutic ODS rats. ODS rats received scorbutic diet with either distilled water containing AA (1 g/l) or distilled water for 2 weeks. AA-deficient rats had 12% of gastric mucosal AA content in AA-sufficient rats. AA-deficient rats showed more severe gastric mucosal lesions than AA-sufficient rats at 1, 3 or 6 h after the onset of WIRS, although AA-deficient rats had a slight decrease in gastric mucosal AA content, while AA-sufficient rats had a large decrease in that content. AA-deficient rats had more decreased gastric mucosal nonprotein SH and vitamin E contents and increased gastric mucosal lipid peroxide content than AA-sufficient rats at 1, 3 or 6 h of WIRS. These results indicate that AA deficiency aggravates WIRS-induced gastric mucosal lesions in ODS rats by enhancing oxidative damage in the gastric mucosa.

Long-term treatment with TGFbeta1 impairs mechanotransduction in bovine aortic endothelial cells

BACKGROUND AND PURPOSE

Vascular endothelial cells play a role in the physiological response to mechanical stress. Transforming growth factor beta1 (TGFbeta1) induces morphological changes in endothelial cells, and this may alter their mechanosensitive responses. The aim of this study was to examine the effects of TGFbeta1 on hypotonic stress (HTS)-induced responses in bovine aortic endothelial cells (BAECs).

EXPERIMENTAL APPROACH

Cultured BAECs were treated with 3 ng ml(-1) TGFbeta1 for 24 h (24h-TGFbeta1) or 7 days (7d-TGFbeta1). Cytosolic actin fibres were stained with rhodamine-phalloidin. Intracellular Ca2+ concentration was measured using fura2. Tyrosine phosphorylation and RhoA expression were assessed by Western blotting. Expression of RhoA mRNA was assessed by real-time PCR.

KEY RESULTS

BAECs developed pseudopod-like processes within 24 h and showed a fibroblast-like appearance after 7 days. HTS induced Ca2+ transients via endogenous ATP release in both control and 24h-TGFbeta1 BAECs but not in 7d-TGFbeta1 BAECs. We have previously shown that HTS-induced ATP release is mediated by sequential activation of RhoA and tyrosine kinases. The basal amount of membrane-bound RhoA was significantly lower in 7d-TGFbeta1 than in 24h-TGFbeta1 or control BAECs. HTS increased the membrane-bound RhoA to the same fractional level in 24h-TGFbeta1 and control BAECs, but its net maximal amount was significantly lower in 7d-TGFbeta1. HTS-induced downstream signals of RhoA activation, i.e. the tyrosine phosphorylation of FAK and paxillin, were markedly suppressed in 7d-TGFbeta1 BAECs.

CONCLUSIONS AND IMPLICATIONS

These results indicate that long-term treatment with TGFbeta1 does not impair mechanoreception in BAECs but impairs mechanotransduction by affecting RhoA membrane translocation.

Thoracoscopic robot-assisted bronchoplasty

BACKGROUND

In robotic surgery, the ideal position of the system, as well as the optimal working angles and the proper positioning of the thoraco ports position is very important. No robot-assisted bronchoplasty has been reported. Our study describes use of the da VinciTM surgical system (Intuitive Surgical, Inc.) for robotic sleeve upper lobectomy in a human fresh cadaver.

METHODS

A male cadaver was placed in the left lateral decubitus position. After thoracoscopic upper lobectomy was performed through the working port and the two ports, the robotic system was then set up behind the cadaver. The working port allowed introduction of the optical scope and the robotic surgical arms were inserted into the thoraco ports. The right bronchus was dissected and wedge was cut out with the robotic scissors. After standard lymph node dissection, end-to-end bronchial anastomosis was performed with robotic instruments. Once the anastomosis was complete, air leakage was checked with saline solution placed in the pleural cavity.

RESULTS

Thoracoscopic robot-assisted bronchoplasty was performed successfully.

CONCLUSIONS

In evaluating various positions of the system we demonstrated that our technique is sufficient approaches to robotic bronchoplasty. This procedure offers specific advantages over conventional bronchoplasty with accuracy and safety.