Elevation of osteopontin levels in brain tumor cells reduces burden and promotes survival through the inhibition of cell dispersal

Osteopontin is highly secreted in the cerebrospinal fluid of patient with posterior pituitary involvement in Langerhans cell histiocytosis

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disease caused by clonal proliferation of CD1a⁺ CD207⁺ cells. Distinguishing pituitary involvement was essential in stratification and treatment of patients with LCH. The diagnosis of pituitary involvement is mainly dependent on hormone abnormalities in the anterior pituitary and magnetic resonance imaging (MRI) scanning in posterior pituitary. Diabetes insipidus (DI) is a serious sequelae and often occurred with pituitary involvement. It is reported that osteopontin (OPN) is highly secreted in the cerebrospinal fluid (CSF) of patients with neurodegenerative diseases in LCH (LCH-ND). However, patients with posterior pituitary involvement account for a larger portion in our hospital. Whether the OPN level could be an auxiliary diagnostic marker for the posterior pituitary involvement or not is still unknown.

METHODS

In our study, we collected CSF samples of 57 children with LCH. The secreted OPN (sOPN) levels in CSF were measured through enzyme-linked immunosorbent assay (ELISA).

RESULTS

After the retrospective analysis of 57 patients with LCH, we found that the sOPN levels in CSF of children with posterior pituitary involvement were significantly higher than that of other groups. After the Pearson Chi-Square test, Fisher's exact test and ROC analysis, we found that the sOPN levels were significantly correlated with posterior pituitary involvement. The cut-off value is 214.14 ng/mL.

CONCLUSION

The sOPN levels were elevated in CSF of LCH children with posterior pituitary involvement. Analysis of the sOPN level may provide more accurate auxiliary diagnostic techniques for the clinic.

Selective osteopontin knockdown exerts anti-tumoral activity in a human glioblastoma model

Osteopontin (OPN), a member of the SIBLING (Small Integrin-Binding LIgand N-linked Glycoprotein) family, is overexpressed in human glioblastoma. Higher levels of OPN expression correlate with increased tumor grade and enhanced migratory capacity of tumor cells. Based on these observations, we explored the possibility that knocking down OPN expression in glioblastoma cells could exert an anti-tumoral activity using an avian in vivo glioblastoma model that mimics closely human gliobastoma. Human U87-MG glioma cells transfected with specific anti-OPN small interfering RNAs (siRNAs) were grafted onto the chicken chorio-allantoic membrane (CAM). OPN-deficient U87-MG cells gave rise to tumors that were significantly smaller than tumors formed from untransfected cells (paired t-test, p < 0.05). Accordingly, the amount of proliferating cells in OPN-deficient tumors showed a six-fold reduction when compared to control tumors. However, OPN inhibition did not affect significantly tumor-associated angiogenesis. In vitro, OPN-silenced U87-MG and U373-MG cells showed decreased motility and migration. This is the first demonstration that OPN inhibition blocks glioma tumor growth, making this invasion-related protein an attractive target for glioma therapy.

Osteopontin, CD44, and NFkappaB expression in gastric adenocarcinoma

PURPOSE

Osteopontin (OPN) binds to CD44 and nuclear factor-kappaB (NFkappaB) and OPN mediates tumorigenesis, invasion and metastasis, but the interrelationships between OPN, CD44 and NFkappaB are not fully understood, and especially in gastric carcinogenesis. We examined the expressions of OPN, CD44, and NFkappaB in untreated gastric adenocarcinomas.

MATERIALS AND METHODS

The materials from 211 cases of gastric adenocarcinoma were immunostained for OPN, CD44 and NFkappaB by using a tissue microarray. The OPN mRNA expression was measured in 10 cases by performing real-time RT-PCR.

RESULTS

The expression of OPN, CD44 and NFkappaB was noted in 61.7%, 11.4% and 26.6% of the adenocarcinoma tissues, respectively. No significant correlation was detected among the expressions of these proteins. The OPN protein expression was negatively correlated with angioinvasion (p<0.05) and patient survival (p<0.05), whereas the CD44 and NFkappaB protein expressions were not correlated with any of the clinicopathological factors we examined. The depth of invasion, lymph node status and perineural invasions were prognostic factors based on the Cox analysis. The OPN mRNA expression showed no significant difference between the adenocarcinoma and the paired normal mucosa on real-time RT-PCR.

CONCLUSION

OPN may have a currently undetermined role in gastric carcinogenesis, and CD44 and NFkappaB may have minor roles in gastric adenocarcinoma.