RGD-p21Ras-scFv expressed prokaryotically on a pilot scale inhibits ras-driven colorectal cancer growth by blocking p21Ras-GTP

BACKGROUND

Ras gene mutation and/or overexpression are drivers in the progression of cancers, including colorectal cancer. Blocking the Ras signaling has become a significant strategy for cancer therapy. Previously, we constructed a recombinant scFv, RGD-p21Ras-scFv by linking RGD membrane-penetrating peptide gene with the anti-p21Ras scFv gene. Here, we expressed prokaryotically RGD-p21Ras-scFv on a pilot scale, then investigated the anti-tumor effect and the mechanism of blocking Ras signaling.

METHODS

The E. coli bacteria which could highly express RGD-p21Ras-scFv was screened and grown in 100 L fermentation tank to produce RGD-p21Ras-scFv on optimized induced expression conditions. The scFv was purified from E. coli bacteria using His Ni-NTA column. ELISA was adopted to test the immunoreactivity of RGD-p21Ras-scFv against p21Ras proteins, and the IC50 of RGD-p21Ras-scFv was analyzed by CCK-8. Immunofluorescence colocalization and pull-down assays were used to determine the localization and binding between RGD-p21Ras-scFv and p21Ras. The interaction forces between RGD-p21Ras-scFv and p21Ras after binding were analyzed by molecular docking, and the stability after binding was determined by molecular dynamics simulations. p21Ras-GTP interaction was detected by Ras pull-down. Changes in the MEK-ERK /PI3K-AKT signaling paths downstream of Ras were detected by WB assays. The anti-tumor activity of RGD-p21Ras-scFv was investigated by nude mouse xenograft models.

RESULTS

The technique of RGD-p21Ras-scFv expression on a pilot scale was established. The wet weight of the harvested bacteria was 31.064 g/L, and 31.6 mg RGD-p21Ras-scFv was obtained from 1 L of bacterial medium. The purity of the recombinant antibody was above 85%, we found that the prepared on a pilot scale RGD-p21Ras-scFv could penetrate the cell membrane of colon cancer cells and bind to p21Ras, then led to reduce of p21Ras-GTP (active p21Ras). The phosphorylation of downstream effectors MEK-ERK /PI3K-AKT was downregulated. In vivo antitumor activity assays showed that the RGD-p21Ras-scFv inhibited the proliferation of colorectal cancer cell lines.

CONCLUSION

RGD-p21Ras-scFv prokaryotic expressed on pilot-scale could inhibited Ras-driven colorectal cancer growth by partially blocking p21Ras-GTP and might be able to be a hidden therapeutic antibody for treating RAS-driven tumors.

Overexpression of Notch3 is associated with metastasis and poor prognosis in osteosarcoma patients

Background

Notch signaling abnormalities are associated with the development of various tumors, including hematopoietic and epithelium-derived tumors. However, the role of Notch signaling in tumors originating from mesenchymal cells is unclear. The effect of Notch3 expression on the prognosis of osteosarcoma and its role and mechanism in osteosarcoma cells have never been reported.

Materials and methods

In this study, we performed a clinicopathological analysis of 70 cases of osteosarcoma, with primary focus on survival. Osteosarcoma cell lines MTH and U2OS were used. After knockdown of Notch3 by lentiviral transfection and siRNA, the cell cycle, cell viability, and wound healing capacity were assessed. Subsequently, the Transwell assay was performed, and the expression levels of hairy and enhancer of split-1 (Hes1) and matrix metalloproteinase 7 (MMP7) were detected by RT-PCR and Western blot assay. The expression of MMP7 was also detected after knockdown of Hes1. Animal experiments were performed by injecting the cell lines MTH of Notch3 knockdown into mice tail veins and comparing the development of lung metastasis with the control group.

Results

Comparison of survival curves showed that Notch3 expression significantly impacts patient survival. Additionally, multivariate analysis revealed that Notch3 is an independent prognostic factor for osteosarcoma. In in vivo experiments, osteosarcoma-associated pulmonary metastasis in nude mice was reduced after Notch3 silencing. The expression of downstream effector molecule, Hes1, and that of the invasion and metastasis-associated proteolytic enzyme, MMP7, were reduced, and MMP7 was further decreased by Hes1 knockdown in in vitro experiments.

Conclusion

Notch3 is a prognostic factor for osteosarcoma and might regulate its invasion and metastasis through the downstream target gene Hes1 and effector MMP7.

Somatostatin receptor scintigraphy in the follow-up of myasthenia gravis

To evaluate the potential value of somatostatin receptor scintigraphy (SRS) using 111In-DTPA (diethylenetriaminepenta acetic acid)-D-Phe1-octreotide (111In-pentetreotide) in patients with recurring or persisting symptoms of myasthenia gravis (MG), 14 consecutive cases with such supplemental receptor imaging during neurological routine follow-up were retrospectively evaluated in this study. All 14 patients underwent SRS in addition to chest computed tomography (CT). Mean follow-up after imaging was 34 months. Eight patients had previous thymectomy, and three patients were referred to surgery after scintigraphy and chest CT. SRS was positive in one of the 14 patients with local recurrence of thymoma and pleural invasion, and negative in the remaining 13 patients. CT was positive for thymoma in three patients, inconclusive in four patients and negative in seven patients. In conclusion, while SRS may be able to detect thymoma lesions including metastases, it seems of limited value in patients with inconspicuous CT findings. Our initial experience fails to point out a benefit of SRS in the management of persisting or recurring MG (with regard to detection of thymic disorders) compared to CT. Whether SRS is useful for differentiating thymoma from non-neoplastic thymic disease may be investigated by larger series. A predominant proportion of patients with unsatisfactory treatment response, however, continue to suffer an unfavourable clinical course despite absent evidence for thymic pathology.

Model calculating annual mean atmospheric dispersion factor for coastal site of nuclear power plant

This paper describes an atmospheric dispersion field experiment performed on the coastal site of nuclear power plant in the east part of China during 1995 to 1996. The three-dimension joint frequency are obtained by hourly observation of wind and temperature on a 100 m high tower; the frequency of the "event day of land and sea breezes" are given by observation of surface wind and land and sea breezes; the diffusion parameters are got from measurements of turbulent and wind tunnel simulation test. A new model calculating the annual mean atmospheric dispersion factor for coastal site of nuclear power plant is developed and established. This model considers not only the effect from mixing release and mixed layer but also the effect from the internal boundary layer and variation of diffusion parameters due to the distance from coast. The comparison between results obtained by the new model and current model shows that the ratio of annual mean atmospheric dispersion factor gained by the new model and the current one is about 2.0.

Quantitative analysis of the tomographic technetium-99m MIBI (99mTc-MIBI) myocardial bullseye display: application to diagnosis of coronary artery disease

In this study, the 99mTc-MIBI myocardial bullseye display of 31 healthy persons and 34 patients with myocardial ischemia and 17 patients with myocardial infarction were analyzed quantitatively; and compared with the results of myocardial tomography analysis and qualitative bullseye analysis. The sensitivities of the three methods were 88.2%, 91.2% and 94.1% respectively (P > 0.05), and the specificities were 93.5%, 83.9% and 83.9% respectively (P < 0.05). On the other hand, the quantitative analysis obviously outperformed the other two methods in the detection of ischemic segments of myocardium near infarction zone (P < 0.01). The quantitative analysis of 99mTc-MIBI myocardial bullseye (quantitative bullseye) was an objective, specific and sensitive method for diagnosis of coronary artery disease.

[Dilatation of stricture of anastomosis after reconstruction of esophagus]

This article reports the experience of the esophagus dilating technique in the treatment of 658 cases of postoperative anastomotic stricture for esophageal cancer and cardiac cancer during the period from May 1983 to May 1993, being delated add up to 3240 times with total effective rate 96.5%, among them 61.6% of the cases less than five, 84.5% of the cases less than ten. Of them, 27 cases (4.1%) had postoperative complications, of which the main ones were esophagus perforation 8 cases (1.2%), hemorrhage of anastomotic stoma 4 cases (0.6%), mediastinitis 1 case (0.2%) and loca trauma 14 cases (2.1%). The operative indication, surgical technique and complication were discussed.

[Early coverage of deep partial-thickness burn wound with porcine dermal collagen membrane. An experimental study]

Collagen was extracted by pepsin digestion from porcine skin and collagen membrane was prepared by salt precipitation. Collagen membrane as a wound dressing was evaluated in a deep partial-thickness burn wounds in a rat model. Burn wound, 4 x 4 cm, were inflicted by exposing skin to 75 degrees C for 15 seconds followed by de-epithelization. Wound healing was assessed by plenimetry of epithelization on day 10 postwounding. Open wounds exhibited a re-epithelialization of 24% of wound area. Collagen membrane dressing significantly improved the healing rate to approximately 70% of wound area.

Porcine dermal collagen as a wound dressing for skin donor sites and deep partial skin thickness burns

Collagen was extracted by pepsin digestion from porcine skin, and collagen membrane was prepared by salt precipitation. The porcine collagen membrane was evaluated as a burn wound dressing in deep partial skin thickness burn wounds in rats. Burn wounds, 4 x 4 cm, were inflicted by exposure of skin to 75 degrees C for 15 s followed by de-epithelialization. Wound healing was assessed by planimetry of epithelialization on day 10 after injury. Open wounds exhibited 24 per cent of wound area re-epithelialized. Collagen membrane dressing significantly improved the healing to 69 per cent of wound area (P < 0.0001). In a completely separate experiment, the porcine collagen membrane was applied as a wound dressing to the donor sites of burn patients, and its effect on wound healing was compared with that of a petroleum jelly gauze dressing. The donor sites covered with petroleum jelly gauze had re-epithelialized by an average of 14.5 days (ranging from 13 to 16 days) after wounding. The wounds dressed with collagen membrane demonstrated a significant increase in the healing rate. Complete re-epithelialization was observed by 10.3 days (ranging from 10 to 12 days) after wounding (P < 0.0001).

Scanning electron microscopic investigation of maxillary lateral incisors with a radicular lingual groove

Fourteen human lateral incisors with a radicular lingual groove were observed under the scanning electron microscope to explore the communications between the groove and the pulp cavity. Observations showed that accessory foramina could be found not only in the groove, but also in the corresponding wall of the pulp cavity and a cross section. A complete lack of closure of the calcified tissues along the groove, allowing for direct connection of the pulp and the periodontium, was not found in these specimens. Therefore, it is suggested that accessory canals are the main way of communication between the pulp and the periodontium of the incisors with a radicular lingual groove. Because the accessory canals could be found either in the crown part or in the root part of the groove, infectious materials may get into the pulp cavity when there are pathologic conditions either through accessory foramina in the crown part or through accessory foramina exposed by localized periodontitis around the groove.

Seeding of arteriovenous prostheses with homologous endothelium. A preliminary report

Endothelial cell seeding of expanded polytetrafluoroethylene (e-PTFE) arteriovenous prostheses was performed to compare seeding with homologous vs. autologous cells and to study the effect of homologous seeding with a larger vs. a smaller number of cells. Sixteen dogs were randomly assigned to four equal groups: I, control; II, light homologous seeded; III, heavy homologous seeded; and IV, autologous seeded. Bilateral femoral arteriovenous loop grafts were inserted in all. Efficiency of seeding was assessed by cell counts of instilled vs. retained cells. All grafts remained patent and were harvested approximately 8 weeks after implantation. Samples were evaluated grossly by scanning electron microscopy and light microscopy. There was a direct correlation between number of cells instilled and number retained for each graft; group III received and retained the largest number (p less than 0.001 and p less than 0.05, respectively). The amount of thrombus deposition on the lumen of all grafts was grossly the same. Endothelium was demonstrated in samples obtained from the midgraft of groups III and IV; in contrast no endothelium was seen in groups I and II. The percentage of endothelialized surface was not determined. No immunologic cellular reaction was detected in any of the samples. We conclude that in the animal laboratory it is possible to seed e-PTFE arteriovenous prostheses successfully with homologous cells and to improve the efficiency of seeding by implanting a larger number of cells obtained from an endothelial cell bank. The potential applications of this technique to the clinical field are discussed herein.

Coverage of full skin thickness burns with allograft inoculated with autogenous epithelial cells

Since the supply of unburned autograft skin may be insufficient to cover very extensive burns, we have prepared allograft skin inoculated with a suspension of uncultured autogenous epithelial cells and grafted this material on to full skin thickness loss wounds. There was a satisfactory 'take' and permanent healing of this mixture of heterogeneous dermis and autogenous epidermis in two out of four patients. In this preliminary report we describe the clinical and histological observations which indicate that in the two patients with successful graft 'take' the epithelial cells proliferated and formed a continuous pale-coloured layer on top of the heterogeneous dermis between 30 and 40 days after application.