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The multifunctional protein - tissue inhibitor of metalloproteinases-1 (TIMP-1) - has been associated with a poor prognosis in several types of cancers including glioblastomas. In addition, TIMP-1 has been associated with decreased response to chemotherapy, and especially the efficacy of the family of topoisomerase (TOP) inhibitors has been related to TIMP-1. As a second line treatment of glioblastomas, the vascular endothelial growth factor (VEGF) antibody bevacizumab is administered in combination with the TOP1 inhibitor irinotecan and glioblastoma cell levels of TIMP-1 could therefore potentially influence the efficacy of such treatment. In the present study, we aimed to investigate whether a high TIMP-1 expression in glioblastoma cell lines would affect the sensitivity to TOP inhibitors, and whether TIMP-1 overexpressing cells would have alterered growth and invasion. We established TIMP-1 overexpressing subclones from two human glioblastoma cell lines. TIMP-1 overexpressing U87MG cells were significantly more resistant than low TIMP-1 expressing clones and parental cells when exposed to SN-38 (TOP1 inhibitor) or epirubicin (TOP2 inhibitor). No significant differences were observed for the TIMP-1 transfected A172 cells. Implantation of both U87MG and A172 spheroids into organotypic brain slice cultures revealed a reduced growth of TIMP-1 overexpressing U87MG spheroids, however, no significant differences in invasion were observed. The present study suggests that TIMP-1 overexpression reduces the effect of TOP inhibitors in glioblastoma. TIMP-1 also appeared to reduce spheroid growth, but did not influence invasion. Whether TIMP-1 plays a role in irinotecan resistance and has a predictive potential in glioblastoma patients remains to be elucidated.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) has been suggested as a marker of prognosis and response to treatment in breast cancer. In vitro, TIMP-1 can regulate shedding of the extracellular domain of HER2 and signalling via the Akt pathway, and we hypothesize that TIMP-1 therefore can affect sensitivity to the HER2-targeting drugs trastuzumab and lapatinib. SK-BR-3 human breast cancer cells were stably transfected with TIMP-1, characterized with regard to TIMP-1 protein expression, proliferation, and functionality of the secreted TIMP-1, and the sensitivity to trastuzumab and lapatinib was studied in five selected single-cell subclones expressing TIMP-1 protein at various levels plus the parental SK-BR-3 cell line. Both trastuzumab and lapatinib reduced cell viability, as determined by MTT assay, but the sensitivity to the drugs was not associated with the expression level of TIMP-1 protein. Western blotting showed that the activation of Akt, PTEN, and HER2 as well as ADAM10 was similar in all clones. In conclusion, in this model, TIMP-1 overexpression does not affect HER2 cleavage by ADAM10 or signalling via the Akt pathway, and TIMP-1 does not influence sensitivity to trastuzumab and lapatinib.

Background Studies in taxane and/or anthracycline refractory metastatic breast cancer (mBC) patients have shown approximately 30 % response rates to irinotecan. Hence, a significant number of patients will experience irinotecan-induced side effects without obtaining any benefit. The aim of this study was to lay the groundwork for development of predictive biomarkers for irinotecan treatment in BC. Methods We established BC cell lines with acquired or de novo resistance to SN-38, by exposing the human BC cell lines MCF-7 and MDA-MB-231 to either stepwise increasing concentrations over 6 months or an initial high dose of SN-38 (the active metabolite of irinotecan), respectively. The resistant cell lines were analyzed for cross-resistance to other anti-cancer drugs, global gene expression, growth rates, TOP1 and TOP2A gene copy numbers and protein expression, and inhibition of the breast cancer resistance protein (ABCG2/BCRP) drug efflux pump. Results We found that the resistant cell lines showed 7–100 fold increased resistance to SN-38 but remained sensitive to docetaxel and the non-camptothecin Top1 inhibitor LMP400. The resistant cell lines were characterized by Top1 down-regulation, changed isoelectric points of Top1 and reduced growth rates. The gene and protein expression of ABCG2/BCRP was up-regulated in the resistant sub-lines and functional assays revealed BCRP as a key mediator of SN-38 resistance. Conclusions Based on our preclinical results, we suggest analyzing the predictive value of the BCRP in breast cancer patients scheduled for irinotecan treatment. Moreover, LMP400 should be tested in a clinical setting in breast cancer patients with resistance to irinotecan. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-2071-1) contains supplementary material, which is available to authorized users.

The microtubule-targeting taxanes are important in breast cancer therapy, but no predictive biomarkers have yet been identified with sufficient scientific evidence to allow clinical routine use. The purposes of the present study were to develop a cell-culture-based discovery platform for docetaxel resistance and thereby identify key molecular mechanisms and predictive molecular characteristics to docetaxel resistance. Two docetaxel-resistant cell lines, MCF7RES and MDARES, were generated from their respective parental cell lines MCF-7 and MDA-MB-231 by stepwise selection in docetaxel dose increments over 15 months. The cell lines were characterized regarding sensitivity to docetaxel and other chemotherapeutics and subjected to transcriptome-wide mRNA microarray profiling. MCF7RES and MDARES exhibited a biphasic growth inhibition pattern at increasing docetaxel concentrations. Gene expression analysis singled out ABCB1, which encodes permeability glycoprotein (Pgp), as the top upregulated gene in both MCF7RES and MDARES. Functional validation revealed Pgp as a key resistance mediator at low docetaxel concentrations (first-phase response), whereas additional resistance mechanisms appeared to be prominent at higher docetaxel concentrations (second-phase response). Additional resistance mechanisms were indicated by gene expression profiling, including genes in the interferon-inducible protein family in MCF7RES and cancer testis antigen family in MDARES. Also, upregulated expression of various ABC transporters, ECM-associated proteins, and lysosomal proteins was identified in both resistant cell lines. Finally, MCF7RES and MDARES presented with cross-resistance to epirubicin, but only MDARES showed cross-resistance to oxaliplatin. In conclusion, Pgp was identified as a key mediator of resistance to low docetaxel concentrations with other resistance mechanisms prominent at higher docetaxel concentrations. Supporting Pgp upregulation as one major mechanism of taxane resistance and cell-line-specific alterations as another, both MCF7RES and MDARES were cross-resistant to epirubicin (Pgp substrate), but only MDARES was cross-resistant to oxaliplatin (non-Pgp substrate).

Platinum chemotherapy remains part of standard therapies in the management of a variety of cancers. Severe side effects and a high degree of resistance to platinum drugs have led numerous researchers to search for predictive biomarkers, which could aid in identifying patients that are the most likely to respond to therapy. The ERCC1-ERCC4 endonuclease plays a critical role in the repair of platinum-DNA damage and has widely been studied in relation to sensitivity to platinum chemotherapy. The standard method to evaluate ERCC1 protein expression is through the use of immunohistochemistry with monoclonal antibody 8F1, an antibody that was recently found to bind an unrelated protein. The present study determines the specificity of a novel antibody, monoclonal antibody 4F9 and presents a method to evaluate ERCC1 expression in colorectal tumor specimens. Using relevant cell lines as controls, the specificity of antibody 4F9 was tested by immunoblotting, immunohistochemistry and immunofluorescence. Scoring guidelines to aid in the evaluation of ERCC1 tumor expression were developed and evaluated in archival formalin-fixed paraffin embedded colorectal cancer specimens. Antibody 4F9 was found to be specific by all methods applied and it was possible to evaluate the ERCC1 expression in the majority (85%) of colorectal cancer tumor specimens.

Tissue inhibitor of metalloproteinase 1 (TIMP-1) is a protein with a potential biological role in drug resistance. To elucidate the unknown molecular mechanisms underlying the association between high TIMP-1 levels and increased chemotherapy resistance, we employed SILAC-based quantitative mass spectrometry to analyze global proteome and phosphoproteome differences of MCF-7 breast cancer cells expressing high or low levels of TIMP-1. In TIMP-1 high expressing cells, 312 proteins and 452 phosphorylation sites were up-regulated. Among these were the cancer drug targets topoisomerase 1, 2A, and 2B, which may explain the resistance phenotype to topoisomerase inhibitors that was observed in cells with high TIMP-1 levels. Pathway analysis showed an enrichment of proteins from functional categories such as apoptosis, cell cycle, DNA repair, transcription factors, drug targets and proteins associated with drug resistance or sensitivity, and drug transportation. The NetworKIN algorithm predicted the protein kinases CK2a, CDK1, PLK1, and ATM as likely candidates involved in the hyperphosphorylation of the topoisomerases. Up-regulation of protein and/or phosphorylation levels of topoisomerases in TIMP-1 high expressing cells may be part of the mechanisms by which TIMP-1 confers resistance to treatment with the widely used topoisomerase inhibitors in breast and colorectal cancer.

The majority of human breast cancers exhibit luminal epithelial differentiation. However, most aggressive behavior, including invasion and purported cancer stem cell activity, are considered characteristics of basal-like cells. We asked the following questions: Must luminal-like breast cancer cells become basal-like to initiate tumors or to invade? Could luminally differentiated cells within a basally initiated hierarchy also be tumorigenic? To answer these questions, we used rare and mutually exclusive lineage markers to isolate subsets of luminal-like and basal-like cells from human breast tumors. We enriched for populations with or without prominent basal-like traits from individual tumors or single cell cloning from cell lines and recovered cells with a luminal-like phenotype. Tumor cells with basal-like traits mimicked phenotypic and functional behavior associated with stem cells assessed by gene expression, mammosphere formation and lineage markers. Luminal-like cells without basal-like traits, surprisingly, were fully capable of initiating invasive tumors in NOD SCID gamma (NSG) mice. In fact, these phenotypically pure luminal-like cells generated larger and more invasive tumors than their basal-like counterparts. The tumorigenicity and invasive potential of the luminal-like cancer cells relied strongly on the expression of the gene GCNT1 , which encodes a key glycosyltransferase controlling O-glycan branching. These findings demonstrate that basal-like cells, as defined currently, are not a requirement for breast tumor aggressiveness, and that within a single tumor there are multiple “stem-like” cells with tumorigenic potential casting some doubt on the hypothesis of hierarchical or differentiative loss of tumorigenicity.

Background Tissue inhibitor of metalloproteinase 1 (TIMP-1) is a protein with a potential biological role in drug resistance. Lack of TIMP-1 protein either alone (Willemoe et al., Eur J Cancer 2009) or in combination with Topoisomerase 2A gene aberrations has been shown to associate with increased benefit from adjuvant treatment with a Topoisomerase 2 inhibitor (epirubicin containing combination chemotherapy) while this association was not observed in patients treated with a non-Topoisomerase 2 inhibitor combination chemotherapy (Ejlertsen et al., JCO 2010). Aim: To further investigate the molecular mechanisms underlying the association between TIMP-1 and epirubicin sensitivity by quantitative phosphoproteomics. Methods: MCF-7 human breast cancer cells were transfected with pcDNA3.1(Hyg)-TIMP-1. Among 11 single cell clones, two TIMP-1 low expressing and two TIMP-1 high expressing clones were selected. The clones were labeled by SILAC (stable isotope labeling with amino acids in cell culture). Lysates were digested with trypsin and fractionated with SCX followed by subsequent enrichment of phosphopeptides by TiO2-based chromatography and desalting by C18 purification. Total peptides and phosphopeptides were analyzed by tandem mass spectrometry and quantified as described (JV Olsen et al., Science Signaling 2010). Selected proteins were confirmed on Western blots. The sensitivity of the four TIMP-1 cell clones was analyzed by treatment of the cells with the following drugs: The Topoisomerase 2 inhibitor epirubicin (an anthracycline). The Topoisomerase 1 inhibitor SN-38 (the active metabolite of irinotecan, a camptothecin analogue) and the combination of these. A specific Topoisomerase 2B inhibitor (XK 469, a quinoxaline analogue and the DNA crosslinker cisplatin. All experiments were determined with an endpoint MTT assay. Results: The quantitative proteomic analyses confirmed the differences in TIMP-1 levels among the four clones. Several proteins were consistently found to be upregulated and/or had changed phosphorylation levels in the TIMP-1 high cells in two biological replicates. Of particular interest was the observation that the phosphorylation status and protein levels of Topoisomerase-1, -2A and -2B were increased in TIMP-1 high expressing cells compared to TIMP-1 low expressing cells. When the four clones were treated with specific Topoisomerase inhibitors, the TIMP-1 high expressing cells exhibited significantly more resistance to all three inhibitors compared to TIMP-1 low expressing cells. When cells were treated with a combination of SN-38 and epirubicin, we observed an additive but not a synergistic effect. At last, cells were treated with cisplatin with no different effect on TIMP-1 high and low expressing cells. Conclusion and perspectives: The observed upregulation of both protein and phosphorylation levels of Topoisomerases in TIMP-1 high cells may be part of the mechanism by which TIMP-1 confers resistance to treatment with Topoisomerase inhibitors in primary breast cancer. Further work will include pathway analyses and hypothesis testing in clinical material. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-01-14.

Breast cancer consists of a variety of cell types with distinct phenotypes. Here, we examine the heterogeneity by a panel of normal human breast lineage markers from a recently described hierarchy. By use of multicolor imaging, we show that random heterogeneity is in fact patterned. Tumor cells exhibit traits of normal luminal-, and basal- progenitors, respectively. By combining fluorescence activated cell sorting and single cell cloning, we demonstrate that the patterned heterogeneity reflects a lineage hierarchy reminiscent of that seen in the normal breast. Distinct classes of tumor cells have differing functional abilities and behavior. Thus, multipotent basal-like tumor cells with stem cell properties give rise to lineage restricted tumor cells with luminal-like properties. Luminal-like tumor cells, in turn, are most aggressive as revealed by soft agar colony formation, invasiveness, and in vivo tumorigenecity. We therefore conclude that breast cancer heterogeneity, to some extend, arise as a consequence of normal-like lineage evolution. However, more importantly, the progeny of cancer stem cells remains deregulated raising serious doubts about the current concept of the cancer stem cell as the ultimate drug target. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4277.