Reexpression of LSAMP inhibits tumor growth in a preclinical osteosarcoma model

Abstract

BackgroundOsteosarcomas are the most common primary malignant tumors of bone, showing complex chromosomal rearrangements with multiple gains and losses. A frequent deletion within the chromosomal region 3q13.31 has been identified by us and others, and is mainly reported to be present in osteosarcomas. The purpose of the study was to further characterize the frequency and the extent of the deletion in an extended panel of osteosarcoma samples, and the expression level of the affected genes within the region. We have identified LSAMP as the target gene for the deletion, and have studied the functional implications of LSAMP-reexpression.MethodsLSAMP copy number, expression level and protein level were investigated by quantitative PCR and western blotting in an osteosarcoma panel. The expression of LSAMP was restored in an osteosarcoma cell line, and differences in proliferation rate, tumor formation, gene expression, migration rate, differentiation capabilities, cell cycle distribution and apoptosis were investigated by metabolic dyes, tumor formation in vivo, gene expression profiling, time-lapse photography, differentiation techniques and flow cytometry, respectively.ResultsWe found reduced copy number of LSAMP in 45/76 osteosarcoma samples, reduced expression level in 25/42 samples and protein expression in 9/42 samples. By restoring the expression of LSAMP in a cell line with a homozygous deletion of the gene, the proliferation rate in vitro was significantly reduced and tumor growth in vivo was significantly delayed. In response to reexpression of LSAMP, mRNA expression profiling revealed consistent upregulation of the genes hairy and enhancer of split 1 (HES1), cancer/testis antigen 2 (CTAG2) and kruppel-like factor 10 (KLF10).ConclusionsThe high frequency and the specificity of the deletion indicate that it is important for the development of osteosarcomas. The deletion targets the tumor suppressor LSAMP, and based on the functional evidence, the tumor suppressor function of LSAMP is most likely exerted by reducing the proliferation rate of the tumor cells, possibly by indirectly upregulating one or more of the genes HES1, CTAG2 or KLF10. To our knowledge, this study describes novel functions of LSAMP, a first step to understanding the functional role of this specific deletion in osteosarcomas.

The combined impact of IgLON family proteins Lsamp and Neurotrimin on developing neurons and behavioral profiles in mouse

“…In order to reveal the potential interactions of Lsamp and Ntm in tissue homeostasis, we examined cellular proliferation and apoptosis in Lsamp -/-, Ntm -/and Lsamp -/-Ntm -/doubledeficient hippocampal cultures. Previously it has been shown that overexpression of Lsamp in cancerous cell lines reduces the rate of proliferation (Barøy et al, 2014); here we showed that the deletion of Lsamp alone did not affect the proliferation rate. However, our double deficient model enabled us to track the influence of Lsamp in combination with Ntm (Fig.…”

“…Coordination between cellular proliferation and apoptosis is necessary for maintaining the delicate balance of internal development, tissue homeostasis, and growth to avoid uncontrolled cellular growth as seen in cancers. Lsamp has been proposed to function as a tumoursuppressor, since it has been found to be downregulated in several cancerous tissues such as acute myeloid leukaemia (Coccaro et al, 2015), osteosarcoma (Barøy et al, 2014) and clear cell renal carcinomas (Chen et al, 2003). The role of Ntm in tumorigenesis is not straightforward; it has often been shown to have opposite impact compared with Lsamp and other IgLONs.…”

A novel long non-coding RNA LSAMP-1 is down-regulated in non-small cell lung cancer and predicts a poor prognosis

“…Furthermore, alterations of ZBTB20, GAP43 and GSK3B adjacent to LSAMP genes are less clear but they are suspected to have suppressed cancerous functions [40,41]. Tale Barøy, et al also reported that re-expression of LSAMP inhibits the growth of osteosarcoma cells and confirmed that LSAMP has tumor suppressor function [42].…”

Using the Mus musculus hybrid zone to assess covariation and genetic architecture of limb bone lengths

“…Several SNPs associated with the autopodal bone length identify the gene Lsamp on chromosome 16. While Lsamp is mostly expressed in the cortical and subcortical regions of the neural limbic system (Zacco et al., ), it was also identified as a causative gene for osteosarcomas (Baroy et al., ). The Y2 receptor gene Npy2r , on chromosome 3, is associated with ulna length.…”