The Expression And Clinical Significance Of Insulin Like Growth Factor1Receptor In Breast Cancer

The First PartAim:Insulin-like growth factor-1receptor (IGFIR) plays an important role in the occurrence initiation and development of invasive breast cancer. The relationship, however, between IGF1R gene with invasive breast cancer prognosis has been controversy in a long time.Methods and materials:Specimens of325primary invasive breast cancer patients were collected to analyze comprehensively the relationship between diagnosis of clinical cases with IGF1R expression, including gene copy number, mRNA expression and protein expression.Results:The results showed that IGFIR mRNA levels were not only associated with the protein expression but also highly correlated with clinical pathological factors. Lower nuclear grade, axillary lymph node-negative, hormone-receptor positive, Her2-negative, or Ki67negative as well as luminal subtype tumors were correlated with higher expression of IGF1R mRNA, which was shown to be a significant univariate parameter for both relapse-free survival(RFS) and breast cancer-specific survival(BCSS) as well as a significant multivariate parameter for BCSS. In the univariate analysis, IGFIR protein expression was found been related with extended BCSS; IGF1R gene copy number, however, was no significantly correlated with IGFIR mRNA or protein expression, and found to been no diagnostic value. In the Luminal tumor subtypes, higher IGFIR mRNA expression was associated with better BCSS.Conclusion:Our results indicated that IGF1R mRNA expression was correlated with protein expression in primary breast cancer and could be used as a prognostic indicator. These results provided important information for further IGF1R targeted therapy.The Second PartAim:IGFIR has recently been believed to play an important role in invasive breast cancer. Quantitative analysis of IGFIR genes expression in breast cancer formalin fixed paraffin embedded (FFPE) was used to evaluate relevance possibility with those extracted from fresh-frozen(FF) tissue. It was also tested to judge its relevance with breast cancer clinical pathologic parameters and evaluate if it could be used as an independent prognosis factor.Methods and materials:We collected77paired FF and FFPE specimen of breast cancer, from whom the IGFIR gene expressions were quantitatively analyzed by qRT-PCR and evaluate their relevance. To a further study, we used a cohort of260breast cancer FFPE specimens to evaluate the feasibility and prognostic value of analyzing IGFIR gene expression.Results:Total RNA was extracted from95.4%of the FFPE samples with concentration at least30ng/μL. RT-PCR based on Taqman methodology was successful in90%of the FFPE samples. IGFIR expression results showed strong correlation between FF and FFPE specimen(Spearman p=0.740.74) as well as with IGFIR protein expression. Kaplan-Meier method showed higher IGF1R mRNA expression was associated with longer RFS and BCSS.Conclusion:Quantitative analysis IGF1R gene of invasive breast cancer from FFPE specimen is reliable and feasible, and is greatly useful to evaluate the biological behavior and prognosis of invasive breast cancer.The Third PartAim:The results of first two parts have confirmed that IGF1R mRNA expression can be used as indicators for invasive breast cancer prognosis and be significantly positive correlation with IGF1R protein expression. However, the mechanism of regulation of IGF1R mRNA and protein expression is still not clear.Methods and materials:Different breast cancer cell lines including ER-positive and ER-negative were selected to detect the differences between IGF1R mRNA and protein expression. To observe the IGF1R mRNA and protein expression, IGF-1was used to activate IGF1R pathway. Furthermore, chromosome proteins co-immunoprecipitation (ChEP) was exerted to detect if IGF1R protein bound with IGF1R gene promoter.Results:ER-positive and ER-negative breast cancer cells showed different pattern of IGFIR expression. IGFIR mRNA and protein expression of ER-positive cells were significantly higher than ER-negative cells; IGF-1activation of IGF1R pathway promoted the up-regulation of IGF1R mRNA and protein expression. ChIP results showed the combination of IGF1R protein and IGF1R gene promoter in different cell lines.Conclusion:The expression of IGFIR was related with ER status, which indicated ER might be involved in the expression of IGF1R. IGF1R proteins bound in the promoter region of its own gene and promoted IGF1R mRNA transcription, which further induced up-regulation of protein expression. These results showed IGF1R mRNA expression and its protein expression was positively correlated.