In OS cells, silencing of TRAF6 mimicked the anti-tumor effects of miR-146b-5p. p16INK4a is an important tumor suppressor gene frequently down-regulated in OS.
In addition, the GA and AA genotypes of rs3217992 in CDKN2A might indicate higher stage and increased risk of lung metastasis of osteosarcoma, resulting in worse prognosis.
We previously established osteosarcoma-initiating (OSi) cells by introducing the gene for c-Myc into bone marrow stromal cells of <i>Ink4a/Arf</i> knockout mice.
A retrospective analysis of p16 expression was performed in 37 patients with high-grade osteosarcoma of the jaw to investigate its potential prognostic and predictive value.
Together, these results indicate that the tumor suppressor p16(INK4) protein represses the carcinogenic process of osteosarcoma cells not only as a cell cycle regulator, but also as a negative regulator of pro-carcinogenic/-metastatic pathways.
In addition, we found that p16 (INK4a) is also downregulated in immortal cells and that coexpression of CREG1 and p16 (INK4a) , an inhibitor of CDK4/6 and Rb phosphorylation, has a greater effect than either CREG1 and p16 (INK4a) alone to reduce cell growth, induce cell cycle arrest and cellular senescence in immortal LFS fibroblasts, osteosarcoma and fibrosarcoma cell lines.
Genomic loss of CDKN2Ainstead of promoter methylation might be a plausible explanation for the rapid proliferation and high aggressiveness of osteosarcoma by simultaneous impairment CDKN2A/p14(ARF) function.
We then identified CDKN2A/p16 protein expression in 88 osteosarcoma patients as a sensitive prognostic marker, thereby bridging the murine MSCs model to human osteosarcoma.
To analyze the genetic and epigenetic alterations affecting the RB1, TP53, p16INK4, and p21WAF1 tumor suppressor genes, loss of heterozygosity (LOH) at 3q and 18q, and the clinical variables of a series of Spanish children with osteosarcoma.
The data presented here demonstrate the importance of genetic and epigenetic alterations in the INK4a/ARF locus for the growth of osteosarcoma and thus will be useful to further understand the biologic behavior of osteosarcoma in association with the defects in the p53 and RB pathways.
In addition, stable transfection of p21CIP1/WAF1 and p16INK4a genes in two osteosarcoma cell lines (KHOS and U2-OS cells) showed that p21CIP1/WAF1 was able to repress the immortal phenotype in both cell lines, whereas temporary over-expression of p16INK4a reversibly inhibited the cell growth.
Similar apoptotic effect was observed upon down-modulation of endogenous E2Fs through overexpression of E2F binding site oligonucleotides in U2OS-Myc cells, upon expression of RbDeltacdk or dnDP-1 in the Myc-amplified HL-60 (ARF-; p53-) human leukemia cells, and upon co-transfection of Myc and RbDeltacdk in SAOS-2 (ARF+; p53-) human osteosarcoma cells but not in human primary fibroblasts.
To examine INK4A gene alterations in uncultured samples of osteosarcoma and the relationship between INK4A and CDK4 alterations, we analyzed the INK4A and CDK4 genes in 87 specimens from 79 patients.
Following infection of human breast (MCF-7, MDA-MB-231, and BT549), osteosarcoma (U-2 OS and Saos-2), cervical (C33a), and lung cancer (H358) cell lines with the recombinant adenovirus Adp16, high levels of p16 expression were observed in all cell lines.
We tested the efficacy of our system by expressing the wt or mutant p16 genes in the osteosarcoma cell line, U20S, which lacks p16 and retains functional retinoblastoma protein (pRb).
Comparison of the genomic sequence with the sequence of the mts1 cDNAs demonstrates presence of two alternatively spliced variants of the mts1 in the human osteosarcoma cell line (OHS).