RESUMO
The signalling adaptor p62 is frequently overexpressed in numerous cancer types. Here, we found that p62 expression was elevated in metastatic breast cancer and its overexpression correlated with reduced metastasis- and relapse-free survival times. Analysis of p62 expression in breast cancer cell lines demonstrated that high p62 expression was associated with the invasive phenotypes of breast cancer. Indeed, silencing p62 expression attenuated the invasive phenotypes of highly metastatic cells, whereas overexpressing p62 promoted the invasion of non-metastatic cells in in vitro microfluidic model. Moreover, MDA-MB-231 cells with p62 depletion which were grown in a three-dimensional culture system exhibited a loss of invasive protrusions. Consistently, genetic ablation of p62 suppressed breast cancer metastasis in both zebrafish embryo and immunodeficient mouse models, as well as decreased tumourigenicity in vivo. To explore the molecular mechanism by which p62 promotes breast cancer invasion, we performed a co-immunoprecipitation-mass spectrometry analysis and revealed that p62 interacted with vimentin, which mediated the function of p62 in promoting breast cancer invasion. Vimentin protein expression was downregulated upon p62 suppression and upregulated with p62 overexpression in breast cancer cells. Linear regression analysis of clinical breast cancer specimens showed a positive correlation between p62 and vimentin protein expression. Together, our findings provide strong evidence that p62 functions as a tumour metastasis promoter by binding vimentin and promoting its expression. This finding might help to develop novel molecular therapeutic strategies for breast cancer metastasis treatment.
Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Metástase Neoplásica/patologia , Proteína Sequestossoma-1/genética , Vimentina/metabolismo , Animais , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Regulação para Baixo/fisiologia , Feminino , Regulação Neoplásica da Expressão Gênica/fisiologia , Células HEK293 , Humanos , Células MCF-7 , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Invasividade Neoplásica/patologia , Recidiva Local de Neoplasia/metabolismo , Recidiva Local de Neoplasia/patologia , Regulação para Cima/fisiologia , Peixe-ZebraRESUMO
Purpose: Mutations in KRAS are considered to be the main drivers of acquired resistance to epidermal growth factor receptor (EGFR) blockade in patients with metastatic colorectal cancer (mCRC). However, the potential role of other genes downstream of the EGFR signaling pathway in conferring acquired resistance has not been extensively investigated.Experimental Design: Using circulating tumor DNA (ctDNA) from patients with mCRC and with acquired cetuximab resistance, we developed a targeted amplicon ultra-deep sequencing method to screen for low-abundance somatic mutations in a panel of genes that encode components of the EGFR signaling pathway. Mutations with significantly increased variant frequencies upon disease progression were selected by using quartile analysis. The functional consequences of the identified mutations were validated in cultured cells.Results: We analyzed 32 patients with acquired cetuximab resistance in a development cohort. Of them, seven (22%) carried five novel PIK3CA mutations, whereas eight (25%) carried previously reported KRAS mutations. Functional studies showed that novel PIK3CA mutations (all in exon 19; p.K944N, p.F930S, p.V955G, p.V955I, and p.K966E) promote cell viability in the presence of cetuximab. Only one novel PIK3CA mutation (p.K944N) was verified in one of the 27 patients with acquired resistance in a validation cohort, simultaneous KRAS and PIK3CA hotspot mutations were detected in two patients. Among the above 59 acquired resistance patients, those with PIK3CA or RAS mutations detected in ctDNA showed a pronounced decrease in progression-free survival than patients with no mutation.Conclusions: The PIK3CA mutations may potentially contribute to acquired cetuximab resistance in patients with mCRC. Clin Cancer Res; 23(16); 4602-16. ©2017 AACR.
Assuntos
Cetuximab/uso terapêutico , Classe I de Fosfatidilinositol 3-Quinases/genética , Neoplasias Colorretais/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/genética , Mutação , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos Imunológicos/uso terapêutico , DNA Tumoral Circulante/sangue , DNA Tumoral Circulante/química , DNA Tumoral Circulante/genética , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Análise Mutacional de DNA , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Proteínas Proto-Oncogênicas p21(ras)/genética , Estudos RetrospectivosRESUMO
Melanoma is a malignant tumor of the melanocytes. microRNAs (miRNAs) are emerging as important regulators of cancer-related processes. A thorough understanding of miRNAs in melanoma progression is important for developing new therapeutic targets. miRNA expression was detected by quantitative PCR. In vitro, MTT assay, colony formation assay, invasion assay and flow cytometry analysis were performed to test the effect of miR-573 on melanoma cells. The effect of miR-573 in vivo was validated using a murine xenograft model. Using quantitative PCR, we found that the expression levels of miR-573 were lower in melanoma tissues and cell lines compared to normal skin tissues. miR-573 upregulation inhibited melanoma cell proliferation and invasion, and overexpression of melanoma cell adhesion molecule (MCAM) could alleviate the effect of miR-573 on melanoma cells. In vivo, miR-573 overexpression groups showed lower rates of tumor growth compared with the control group. In conclusion, our results demonstrate that the elevated MCAM expression due to miR-573 reduction is essential in melanoma initiation and progression.
