Long interspersed nucleotide acid element-1 ORF-1 protein promotes proliferation and invasion of human colorectal cancer LoVo cells through enhancing ETS-1 activity

The human proto-oncogene long interspersed nucleotide acid element-1 (LINE-1) open reading frame-1 protein (ORF-1p) is involved in the progress of several cancers. The transcription factor ETS-1 can mediate the transcription of some downstream genes that play specific roles in the regulation of cancerous cell invasion and metastasis. In this study, the effects of LINE-1 ORF-1p on ETS-1 activity and on the proliferation and invasion of human colorectal cancer LoVo cells were investigated. Results showed that the overexpression of LINE-1 ORF-1p enhanced the transcription of ETS-1 downstream genes and increased their protein levels, and downregulation of the LINE-1 ORF-1p level by small interfering RNA (siRNA) reduced the transcriptional activation of ETS-1. In addition, overexpression of LINE-1 ORF-1p promoted LoVo cell proliferation and anchor-independent growth, and a knockdown of the LINE-1 protein level by siRNA reduced the proliferation and anchor-independent growth ability of LoVo cells. In vivo data revealed that LINE-1 ORF-1p overexpression increased LoVo tumor growth in nude mice, whereas the siRNA knockdown of endogenous LINE-1 ORF-1p expression decreased LoVo cell growth in nude mice. Therefore, LINE- 1 ORF-1p could promote LoVo cell proliferation and invasion both in vitro and in vivo, indicating that it might be a useful molecular target for the treatment of human colorectal cancer.

Evidence of compromised circulation in the pathogenesis of optic nerve damage in chronic glaucomatous rabbit

The protective effect of improving the microcirculation on the retinal ganglion cells (RGC) and the ultrastructure of the optic nerve after intravenous (i.v.) use of Salviae miltiorrhiza (SMR) was studied in a chronic intraocular hypertension model in 36 rabbits. These rabbits were treated with topical 0.5% timolol, or i.v. SMR or i.v. 0.9% saline for 1, 3, 5 or 8 weeks. The intraocular pressure (IOP) was 19.6 +/- 2 mmHg and the RGC density was 1140 +/- 121.2/mm2 in control rabbits. After one week of intraocular hypertension (IOP between 30 and 40 mmHg), the RGC densities decreased to between 650 and 820/mm2. Following the use of timolol for 1 to 8 weeks, IOP returned to control level and the RGC density increased to 1015 +/- 7/mm2. After treatment with i.v. saline for 8 weeks, the RGC density decreased progressively from 651 +/- 1/mm2 at the beginning of treatment to 83 +/- 3/mm2. The RGC density of those rabbits treated with i.v. SMR for 8 weeks remained virtually unchanged (658 +/- 5/mm2) compared to the RGC density at the beginning of the treatment. Severe ultrastructural damage of optic nerve and collapsed capillaries were found in rabbits treated with saline while these findings were mild in rabbits treated with SMR. During these periods of treatment, the intraocular hypertension did not decrease in rabbits treated with either saline or SMR. From these findings and the fact that SMR improves local microcirculation, it is considered that the compromised microcirculation is one of the mechanisms in the pathogenesis of optic nerve damage in chronic glaucoma.

Development of experimental chronic intraocular hypertension in the rabbit

There are many unanswered questions about chronic glaucoma which cannot be investigated in the available animal models. The present experiments were designed to develop a rabbit model of chronic intraocular hypertension with characteristics similar to human chronic glaucoma by ligating vortex veins or by making single or multiple intraocular injections of 0.5% or 1% alpha-chymotrypsin, 20% chondroitin sulphate, 2% hydroxypropyl methylcellulose, 2% sodium carboxymethylcellulose or 1% or 2% methylcellulose. Evaluation was based on the clinical findings, intraocular pressure and the retrograde axoplasmic transport function of the optic nerve using a horseradish peroxidase histochemical technique. Most methods either failed to produce moderate chronic intraocular hypertension or were associated with other complications. However, a reliable and relatively long period (eight weeks) of intraocular hypertension was developed by a series of four intra-anterior chamber injections of 1% or 2% methylcellulose. This model has been proved suitable for the study of structural and functional damage to the retina and optic nerve caused by chronic glaucoma.

[The effect of Inj. Salviae Miltiorrhizae Co. on the retrograde axoplasmic transport in the optic nerve of rabbits with chronic IOP elevation]

With the horseradish peroxidase histochemical technique and electron microscope, the effects of 0.5% timolol, Inj. Salviae Miltiorrhizae Co. and their combination on the retrograde axoplasmic transport in the optic nerve of 230 rabbit models of chronic IOP elevation were studied. The results showed that (1) the nerve damage in chronic glaucoma was due to multiple factors; (2) the use of a drug that improved microcirculation in combination with an IOP depressor better protected the optic nerve functions than did the latter alone; and (3) Inj. Salviae Miltiorrhizae Co. improved the optic nerve axoplasmic transport under chronic IOP elevation. The mechanism of the drug in protecting the optic nerve could be through its actions of improving the local microcirculation and the tolerance of nerve tissues to anoxia.