PTEN loss activates a functional AKT/CXCR4 signaling axis to potentiate tumor growth and lung metastasis in human osteosarcoma cells.

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents. Loss of the tumor suppressor PTEN or activation of chemokine receptor CXCR4 has been demonstrated to associate with OS respectively. However, the signaling mechanism underlying PTEN-mediated antitumor effect remains largely unknown, and the crosstalk between PTEN and CXCR4 in OS has not been investigated. Here, we uncover a PTEN/AKT/CXCR4 pathway nexus in highly tumorigenic and metastatic human 143B OS cells. Loss of PTEN activates AKT/CXCR4 signaling axis and regulates a series of tumor cell behaviors. Notably, ERK is inversely regulated by PTEN and its activation occurs downstream of AKT but upstream of CXCR4, suggesting this kinase to be an important mediator between AKT and CXCR4. In vivo studies show that overexpression of PTEN dramatically attenuates bone destruction, and this inhibition is associated with reduced CXCR4 expression in tumors. CXCR4 inhibitor AMD3100 also markedly suppresses tumor growth in the bone. In addition, PTEN overexpression or AMD3100 substantially inhibits tumor expansion in the lung. Our studies highlight a novel PTEN/AKT/CXCR4 signaling nexus in OS tumor growth and lung metastasis, and provide a strong rationale to consider PTEN restoration or CXCR4 blockade for the treatment of aggressive OS in humans.

[A model of lumbar disc degeneration on the early stage in rhesus monkey with minimally invasive technique].

OBJECTIVE: To establish a novel model of lumbar disc degeneration on the early stage in the rhesus monkey using percutaneous needle puncture guided by CT. METHODS: (1) Thirteen rhesus monkeys aged from 4 to 7 years, female 7 and male 6 were selected for establishing a model of the early stage of lumbar disc degeneration. (2)13 monkeys, 91 discs were divided into 3 groups: 64 discs from L1/2 to L5/6 were percutaneous punctured with a needle 20G as experimental group and 1 disc with a needle 15G as puncture control group and 26 discs were not be punctured from L6,7 to L7-S1 as control group. (3) Lumbar disc localization for needle puncture was guided by CT. All discs were examined by MRI, the HE, Masson's trichrome, Safranine-O and immunohistochemical staining of type II collagen before disc puncture and after puncture at 4, 8 and 12 weeks. RESULTS: MRI: (1) Experimental group: Pfirmann's Grade I was shown at postoperation 4, 8 and 12 weeks; (2) Puncture control group: Grade III was shown at postoperation 4 weeks and Grade IV at 8 weeks; (3) CONTROL GROUP: Grade I was shown at postoperation 4, 8 and 12 weeks. Histological examination: (1) In experimental group, there was no any change at postoperation 4 weeks, and the cell population of the nucleus was decreased at 8 weeks and more decreased at 12 weeks in HE. (2) There was no any change at postoperation 4 weeks, the clefts among the lamellae of the annulus fibrosus (AF) were shown at 8 weeks and more wider of the clefts of AF at 12 weeks in Masson's trichrome. (3) No any change was shown at postoperation 4 weeks, proteoglycan were progressively decreased at 8 and 12 weeks in Safranine-O. (4) No statistically significant difference in positive rate was observed at 4 and 8 weeks compared with control group in immunohistochemical staining of type II collagen. There was statistical difference at 12 weeks compared with control group (P<0.05). In puncture control group postoperation 8 weeks, the morphology of cell of nucleus pulposus was not clear in HE. The wider clefts of lamellae of the AF were shown in Masson's trichrome. The proteoglycan was obviously decreased in Safranine-O. Immunohistochemical staining collagen II synthesized was decreased. In normal control group, no any change was shown at 4, 8 and 12 weeks. CONCLUSIONS: The degeneration of lumbar intervertebral disc on the early stage could be induced by the percutaneous needle puncture (20G) to the annulus fibrosus. The assessment of disc degeneration on early stage is not shown on MRI and only confirmed by histological examination.

[Accuracy and related affecting factors of somatosensory evoked potential monitoring in cervical and thoracic surgery].

OBJECTIVE: To evaluate the accuracy and related affecting factors of the intra-operative somatosensory evoked potential monitoring in cervical and thoracic surgery. METHODS: Cortical somatosensory evoked potential (CSEP) monitoring and sub cortical somatosensory evoked potential (Sub-CSEP) monitoring were performed in cervical and thoracic surgery. Somatosensory evoked potential (SEP) changes were recorded during anaesthesia and operation and postoperative, which could be used to evaluate accuracy of SEP. RESULTS: Bilateral CSEP wave abnormalities were related to anaesthesia, decreasing wave amplitudes did not reach the alarming standard. Intra-operative manipulation to affect spinal cord would influence iso-lateral wave abnormality of CSEP and sub-CSEP, decreasing amplitudes reached the alarming standard. Local hypothermia such as cold water irrigating spinal cord would be to prolong the latent period. Low mean arterial pressure (MAP) mostly influenced amplitudes. Changes of SEP in local hypothermia and MAP did not reach the alarming standard. CONCLUSIONS: CSEP and Sub CSEP can reflex physiopathological condition of spinal cord, it is useful in evaluating spinal cord function and providing the safety for cervical and thoracic surgery.

Gene expression of collagen types IX and X in the lumbar disc.

OBJECTIVE: To study gene expression of collagen types IX and X in human lumbar intervertebral discs during aging and degeneration and to explore the role of collagen types IX and X in disc degeneration. METHODS: Fetal, adult and pathologic specimens were subjected to in situ hybridization with cDNA probes to investigate mRNA-expressions of types IX and X collagen gene. RESULTS: In fetal intervertebral discs, positive mRNA hybridization signals of type IX collagen were concentrated in the nucleus pulposus and the inner layer of anulus fibrosus. Interstitial matrix of the nucleus pulposus also showed positive type X collagen staining. Positive mRNA hybridization signals of types IX and X were not detected in the middle and outer layers of anulus fibrosus. In adult specimens, expression of type IX collagen mRNA was markedly decreased. No hybridization signals of type X collagen was observed. As for pathological specimens, there was no gene expression of type IX collagen. In severe degenerated discs from adults, there were focal positive expressions of type X collagen. CONCLUSIONS: Obvious changes of collagen gene expression occur with aging. Expression of type IX collagen decreases in adult and pathological discs. Results of type X collagen expression suggest that type X collagen is expressed only in older adult and senile discs (i.e., when disc degeneration has already reached a terminal stage), indicating the terminal stage of degeneration.