Transscleral laser thermotherapy of hamster Greene melanoma: inducing tumour necrosis without scleral damage

Necrosis of osteosarcoma cells induces the production and release of high-mobility group box 1 protein

Osteosarcoma is among the commonly observed malignancies worldwide. High-mobility group box 1 protein (HMGB1) is a highly conserved protein and is involved in the progression of various types of human cancer. The aim of the present study was to explore whether the level of HMGB1 was involved in the necrosis of osteosarcoma cells. Doxorubicin (DXR), as an inducer of necrosis, was administered to human osteosarcoma cell lines (MG63, Saos-2 and U2OS), and the results indicated that 0.5 µg/ml DXR significantly induced the necrosis of MG63 cells (P<0.01), while 0.5 and 1.0 µg/ml DXR suppressed the viability of MG63 and U2OS cells (P<0.05), relative to untreated controls. Additionally, treatment with DXR was observed by western blot analysis to markedly increase the expression levels of HMGB1 in MG63 cells, and to significantly increase the levels of secreted HMGB1 in the supernatants of MG63 and U2OS cells (P<0.01). In conclusion, cell necrosis increased the level of HMGB1 in osteosarcoma cells, as well as the level of secreted HMGB1 in cell supernatants. Therefore, HMGB1 may be a potential target in molecular therapy for patients with osteosarcoma.

Animal Eye Models for Uveal Melanoma

Animal models play an important role in understanding tumor growth and may be used to develop novel therapies against human malignancies. The significance of the results from animal experiments depends on the selection of the proper model. Many attempts have been made to create appropriate animal models for uveal melanoma and its characteristic metastatic behavior. One approach is to use transgenic animal models or to implant tumor cells. A variety of tumor types have been used for this purpose: tumor cells, such as Greene melanoma, murine B16 melanoma, and human uveal melanoma cells, may be implanted in the eyes of hamsters, rats, rabbits, and mice, among others. Various inoculation routes, including into the anterior chamber and posterior compartment, and retro-orbitally, have been applied to obtain tumor growth mimicking ocular uveal melanoma. However, when we choose animal models, we must be conscious of many disadvantages, such as variable tumor growth, or the need for immunosuppression in xenogeneic grafts. In this paper, we will discuss the various eye models.

Assessment of the effect of laser irradiations at different wavelengths (660, 810, 980, and 1064 nm) on autophagy in a rat model of mucositis

It is known that high-dose radiation has an effect on tissue healing, but tissue healing does not occur when low dose radiation is applied. To clarify this issue, we compare the treatment success of low dose radiation with programmed cell death mechanisms on wounded tissue. In this study, we aimed to investigate the interactions of low and high-dose radiation using an autophagic mechanism. We included 35 adult Wistar-Albino rats in this study. All animals were injected with 100 mg/kg of 5-fluorouracil (5-FU) on the first day and 65 mg/kg of 5-FU on the third day. The tips of 18-gauge needles were used to develop a superficial scratching on the left cheek pouch mucosa by dragging in a linear movement on third and fifth days. After mucositis formation was clinically detected, animals were divided into five groups (n = 7). Different wavelengths of laser irradiations (1064 nm, Fidelis Plus, Fotona, Slovenia; 980 nm, FOX laser, A.R.C., Germany; 810 nm, Fotona XD, Fotona, Slovenia; 660 nm, HELBO, Medizintechnik GmbH, Wels, Austria) were performed on four groups once daily for 4 days. The laser irradiation was not performed on the control group. To get the tissue from the left cheek at the end of fourth day from all animals, oval excisional biopsy was performed. Molecular analysis assessments of pathological and normal tissue taken were performed. For this purpose, the expression analysis of autophagy genes was performed. The results were evaluated by normalization and statistics analysis. We found that Ulk1, Beclin1, and Atg5 expression levels were increased in the rats when the Nd:YAG laser was applied. This increase showed that a 1064-nm laser is needed to activate the autophagic mechanism. However, in the diode applications, we found that Beclin1, Atg10, Atg5, and Atg7 expressions numerically decreased. Atg5 is responsible for the elongation of autophagosome. Becn1 is a control gene in the control mechanism of autophagy. The reduction of the expression of these genes leads us to think that it may depend on the effect of drug (5-FU) used to form model. Expressions of therapeutic genes increase to ensure hemostasis, but in our study, expressions were found to decrease. More detailed studies are needed.

Transscleral delivery of Nd: YLF laser at 1,047 nm causes vascular occlusion in experimental pigmented choroidal melanoma

PURPOSE

The aims of this study were to determine the scleral attenuation of focused neodymium: yttrium-lanthanum-fluoride laser at 1,047 nm applied transsclerally and whether transscleral delivery can close the vascular supply at the base of experimental choroidal melanoma in rabbits.

METHODS

Fifty-two New Zealand albino rabbits were included. Scleral laser attenuation was measured across fresh sclera. B16F10 melanomas were established in the subchoroidal space of 49 rabbits. Twenty-one animals were killed immediately after transscleral treatment, 14 were followed for 2 weeks to 4 weeks, and 14 were followed without treatment. Ophthalmoscopy, fundus photographs, and fluorescein angiography were performed before treatment, immediately after, and weekly during the follow-up. Eyes were examined by light microscopy.

RESULTS

Sclera attenuated laser energy by 31% ± 7%. Immediately after treatment, angiography showed diffuse hypofluorescence in 71% (15 of 21 rabbits). Light microscopy showed vascular occlusion extending at least two thirds of the tumor thickness from the base. Seven of the 14 tumors followed for 15 days ± 8 days were eradicated. There was no correlation between tumor height and eradication.

CONCLUSION

Rabbit sclera attenuated 31% ± 7% of laser energy. A single transscleral treatment causes tumor vascular closure at the base and may serve as an adjuvant therapy to ensure destruction of deep and intrascleral tumor cells.

Changes in immunological markers and influx of macrophages following trans-scleral thermotherapy of uveal melanoma

PURPOSE

In trans-scleral thermotherapy (TSTT), heat is applied through the sclera in order to target an intraocular uveal melanoma. Previously, it had been shown that in uveal melanoma, hyperthermia and transpupillary thermotherapy influenced expression of immunologically relevant proteins, such as S100, HLA and heat-shock proteins (HSPs). We investigated whether TSTT induced similar changes.

METHODS

Experimental TSTT was applied on eleven uveal melanomas prior to enucleation. Each tumour sample was processed for histopathological examination; immunohistochemical analysis was performed to determine expression of S100, HLA, HSPs and macrophage markers.

RESULTS

In TSTT-treated areas, expression of S100 and different HSPs was lost, while an upregulated expression of HSP GP96 was observed at the border of these areas. Expression levels of HLA-A and HLA-B varied between tumours and were not influenced by TSTT. The borders of the TSTT-treated areas showed high numbers of infiltrating macrophages, which were predominantly of the M2 phenotype.

CONCLUSION

TSTT has an effect on immunological parameters with local loss of expression of HSPs and S100. The influx of M2 macrophages around the TSTT-treated areas indicates the presence of an innate immune reaction against the induced necrosis, suggesting that TSTT-treated tumour cells are removed by a macrophage-mediated tissue repair mechanism.

Protective effect of autophagy in laser-induced glioma cell death in vitro

BACKGROUND AND OBJECTIVE

Laser phototherapy could be potentially used for cancer treatment, but the mechanisms of laser-induced cell death are not completely understood. Autophagy is the process in which the damaged cellular proteins and organelles are engulfed by and destroyed in acidified multiple-membrane vesicles. The aim of the present study was to investigate the role of autophagy in laser-induced tumor cell death in vitro.

STUDY DESIGN/MATERIALS AND METHODS

The monolayers of U251 human glioma tumor cells were exposed to 532 nm laser light from a single mode frequency-doubled Nd-YVO4 laser. A flattened Gaussian radial profile of laser beam (0.5-4 W) was used to uniformly illuminate entire colony of cells for various amounts of time (15-120 seconds) in the absence of cell culture medium. The cells were grown for 24 hours and the cell viability was determined by crystal violet or MTT assay. The presence of autophagy was assessed after 16 hours by fluorescence microscopy/flow cytometric analysis of acridine orange-stained autophagolysosomes and Western blot analysis of the autophagosome-associated LC3-II protein. The concentration of the principal pro-autophagic protein beclin-1 was determined after 6 hours by cell-based ELISA.

RESULTS

The intracytoplasmic accumulation of autophagic vesicles, increase in LC3-II and up-regulation of beclin-1 expression were clearly observed under irradiation conditions that caused approximately 50% cytotoxicity. Post-irradiation addition of three different autophagy inhibitors (bafilomycin A1, chloroquine, or wortmannin) further increased the laser-induced cytotoxicity, without affecting non-irradiated cells.

CONCLUSIONS

These data indicate that beclin-1-dependent induction of autophagy can protect glioma cells from laser-mediated cytotoxicity.

Transscleral thermotherapy with laser-induced and conductive heating in hamster Greene melanoma

The purpose of this study was to investigate the cytotoxic effect of heat as induced by transscleral thermotherapy (TSTT), which may be of interest in the treatment of patients with choroidal melanoma. The aim of TSTT is to heat both the sclera and the tumor up to a cytotoxic temperature of about 60 degrees C. TSTT was performed in hamsters with subcutaneously implanted Greene melanoma covered by a specimen of human donor sclera of thickness 0.5, 0.7 or 0.9 mm. A newly developed applicator, which combines conductive episcleral heating at 60 degrees C with laser-induced heating, was used at laser powers ranging from 500 to 1500 mW delivered by an 810 nm diode laser, beam diameter 3 mm, and exposure time 1 min. Temperatures were measured at the scleral surface and at the sclera-tumor interface. The extent of tumor necrosis was examined by light microscopy and the sclera was examined by polarized light microscopy. Maximal depth of tumor necrosis without scleral damage was 4.4 (SD 1.5) mm. The temperature at the scleral surface after TSTT was 58.8 (SD 2.4) degrees C. The temperature at the sclera-tumor interface ranged from 56.4 (SD 3.7) degrees C at 500 mW to 65.3 (SD 4.4) degrees C at 1250 mW laser power. Structural changes to the scleral collagen started to develop at 1250 mW. TSTT with combined laser-induced and conductive heating caused cytotoxic temperatures in the tumor and the sclera, which were well tolerated by the scleral collagen.

Combined plaque radiotherapy and transpupillary thermotherapy in choroidal melanoma: 5 years' experience

AIM

To evaluate the results of combined plaque radiotherapy and transpupillary thermotherapy (TTT) in 50 consecutive patients 5 years after treatment.

METHODS

50 adult patients with choroidal melanoma were treated with ruthenium-106 ((106)Ru) plaque radiotherapy combined with TTT. A flat scar was the preferred end point of treatment. The mean tumour thickness was 3.9 mm (range 1.5-8.0 mm), the mean tumour diameter was 11.3 mm (range 5.8-15.0 mm). TTT was performed with an infrared diode laser at 810 nm, a beam diameter of 2-3 mm, and 1 minute exposures. Tumours >5 mm thick received an episcleral contact dose of 800 Gy (106)Ru; tumours <or=5 mm thick received a contact dose of 600 Gy (106)Ru. TTT was repeated in case of incomplete tumour regression after combined therapy.

RESULTS

Complete tumour regression was obtained in 45 patients. It required one, two, or three TTT sessions in 32, 11, and two patients, respectively. In tumours <or=3 mm thick complete flattening was achieved significantly faster than in tumours >3 mm thick (log rank test p = 0.01). Eight melanomas were amelanotic, seven of which required multiple TTT sessions. In one patient the tumour recurred at the central margin of the treated area; this eye was enucleated. In one patient the tumour failed to regress 6 months after treatment and enucleation was performed at the patient's request. Three eyes developed severe proliferative retinopathy. Radiation maculopathy caused a loss of the best corrected visual acuity: before treatment 31 patients had a best corrected visual acuity of 20/60 or better but in only 12 patients did it remain in this range 5 years after treatment. Three patients developed distant metastasis to the liver.

CONCLUSION

The 5 year results for combined plaque radiotherapy and TTT as treatment for choroidal melanoma are favourable in terms of complete tumour regression and low rate of recurrences; however, there was considerable loss of visual acuity as a result of radiation maculopathy.

Clinicopathologic findings in choroidal melanomas after failed transpupillary thermotherapy

PURPOSE

To review the clinicopathologic features of eyes enucleated after failed transpupillary thermotherapy.

DESIGN

Retrospective review.

METHODS

Pathology reports in the L.F. Montgomery Laboratory between 1998 and 2002 were searched for enucleated eyes with choroidal melanoma that had been treated only by transpupillary thermotherapy (TTT) prior to enucleation. The clinical features of the patients, including ultrasonography examination, were reviewed and compared with the pathologic findings.

RESULTS

Seven eyes from seven patients had been enucleated, representing 8% of eyes treated with TTT at our institute during the period studied. The primary indication for enucleation was tumor growth. The melanomas tended to grow laterally, with minimal if any increase in thickness. Five of the seven eyes histologically demonstrated extrascleral extension, which was detected by ultrasonography prior to enucleation in only one of those eyes.

CONCLUSIONS

Choroidal melanoma may continue to grow along a path of least resistance after TTT. The melanoma may extend laterally in the choroid and through emissary canals. Early extrascleral extension may be difficult to detect by ultrasonography.

Thermotherapy in the management of choroidal melanoma

During the past 20 years of enucleation, which was the standard treatment for choroidal melanoma over more than a century, has largely been replaced by eye salvaging therapies such as radiotherapy or local resection. In 1995 transpupillary thermotherapy (TTT) using an infrared diode laser was introduced as a new conservative therapy for patients with choroidal melanoma. TTT can be defined as a heat treatment modality, which is delivered through a dilated pupil to the tumour surface. The technique uses a wide diode laser beam diameter with a low irradiance and a long exposure time. TTT induces tumour necrosis at sub-photocoagulation levels by a direct cell destructive effect with only a few ocular complications. TTT can be performed as sole therapy or combined with plaque radiotherapy, thus permitting a lower radiation dose. For amelanotic tumours dye-enhanced TTT with indocyanine green can be used. In this paper we review the role of sole or combined TTT, related to the current other treatment modalities for choroidal melanoma.