Jonas Nilsson

Prostate cancer-derived urine exosomes: a novel approach to biomarkers for prostate cancer

Herein, we describe a novel approach in the search for prostate cancer biomarkers, which relies on the transcriptome within tumour exosomes. As a proof-of-concept, we show the presence of two known prostate cancer biomarkers, PCA-3 and TMPRSS2:ERG the in exosomes isolated from urine of patients, showing the potential for diagnosis and monitoring cancer patients status.

Myc pathways provoking cell suicide and cancer.

A paradox for the cancer biology field has been the revelation that oncogenes, once thought to simply provide advantages to a cancer cell, actually put it at dire risk of cell suicide. Myc is the quintessential oncogene in this respect, as in normal cells it is required for cell cycle traverse, whereas in cancers it is overexpressed and functions as the angiogenic switch. Nonetheless, Myc overexpression kills normal cells dead in their tracks. Here we review Myc-induced pathways that contribute to the apoptotic response. Molecular analysis of Myc-induced tumors has established that some of these apoptotic pathways are essential checkpoints that guard the cell from cancer, as they are selectively bypassed during tumorigenesis. The precise mechanism(s) by which Myc targets these pathways are largely unresolved, but we propose that they involve crosstalk and feedback regulatory loops between arbiters of cell death.

Topoisomerase II{alpha} Gene Amplification Predicts Favorable Treatment Response to Tailored and Dose-Escalated Anthracycline-Based Adjuvant Chemotherapy in HER-2/neu-Amplified Breast Cancer: Scandinavian Breast Group Trial 9401.

PURPOSE Amplification of the HER-2/neu and topoisomerase IIalpha (TOP2A) genes has been linked to the effects of anthracyclines. Their role in predicting the outcome of anthracycline-based adjuvant chemotherapy for breast cancer patients has remained controversial. PATIENTS AND METHODS The present substudy of the Scandinavian Breast Group trial 9401, in which an epirubicin-based regimen (nine courses of tailored and dose-escalated fluorouracil, epirubicin, and cyclophosphamide [FEC]) was compared with three or four courses of standard FEC followed by bone marrow-supported high-dose chemotherapy (cyclophosphamide, thiotepa, and carboplatin), included high-risk breast cancer patients (with eight or more positive axillary lymph nodes or at least five nodes with additional poor prognostic indicators). Amplification of HER-2/neu was determined retrospectively in paraffin-embedded tumor tissue sections by chromogenic in situ hybridization. TOP2A was tested only in HER-2/neu-amplified tumors. RESULTS HER-2/neu amplification alone, which was present in 32.7% of the tumors, was a strong prognostic factor for short relapse-free (P = .0034) and overall survival (P = .0008) but showed no direct association with treatment assignment. TOP2A coamplification, which was present in 37% of HER-2/neu-amplified tumors, was associated with better relapse-free survival in patients treated with tailored and dose-escalated FEC (hazard ratio [HR] = 0.45; P = .049). A statistical multivariate Coxs regression analysis confirmed the predictive significance of TOP2A coamplification (HR = 0.30; P = .020) in HER-2/neu-amplified tumors. There was no such association in patients with HER-2/neu-amplified tumors without TOP2A gene amplification. CONCLUSION Coamplification of HER-2/neu and TOP2A may define a subgroup of high-risk breast cancer patients who benefit from individually tailored and dose-escalated adjuvant anthracyclines.

LRIG1 restricts growth factor signaling by enhancing receptor ubiquitylation and degradation

Kekkon proteins negatively regulate the epidermal growth factor receptor (EGFR) during oogenesis in Drosophila. Their structural relative in mammals, LRIG1, is a transmembrane protein whose inactivation in rodents promotes skin hyperplasia, suggesting involvement in EGFR regulation. We report upregulation of LRIG1 transcript and protein upon EGF stimulation, and physical association of the encoded protein with the four EGFR orthologs of mammals. Upregulation of LRIG1 is followed by enhanced ubiquitylation and degradation of EGFR. The underlying mechanism involves recruitment of c‐Cbl, an E3 ubiquitin ligase that simultaneously ubiquitylates EGFR and LRIG1 and sorts them for degradation. We conclude that LRIG1 evolved in mammals as a feedback negative attenuator of signaling by receptor tyrosine kinases.

Risk of acute myeloid leukemia and myelodysplastic syndrome in trials of adjuvant epirubicin for early breast cancer : Correlation with doses of epirubicin and cyclophosphamide

PURPOSE We reviewed follow-up of patients treated in 19 randomized trials of adjuvant epirubicin in early breast cancer to determine incidence, risk, and risk factors for subsequent acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). PATIENTS AND METHODS The patients (N = 9,796) were observed from the start of adjuvant treatment (53,080 patient-years). Cases of AML or MDS (AML/MDS) were reported, with disease characteristics. Incidence and cumulative risk were compared for possible risk factors, for assigned regimens, and for administered cumulative doses of epirubicin and cyclophosphamide. RESULTS In 7,110 patients treated with epirubicin-containing regimens (92% of whom also received cyclophosphamide), 8-year cumulative probability of AML/MDS was 0.55% (95% CI, 0.33% to 0.78%). The risk of developing AML/MDS increased in relation to planned epirubicin dose per cycle, planned epirubicin dose-intensity, and administered cumulative doses of epirubicin and cyclophosphamide. Patients with administered cumulative doses of both epirubicin and cyclophosphamide not exceeding those used in standard regimens (</= 720 mg/m(2) and </= 6,300 mg/m(2), respectively) had an 8-year cumulative probability of developing AML/MDS of 0.37% (95% CI, 0.13% to 0.61%) compared with 4.97% (95% CI, 2.06% to 7.87%) for patients administered higher cumulative doses of both epirubicin and cyclophosphamide. CONCLUSION Patients treated with standard cumulative doses of adjuvant epirubicin (</= 720 mg/m(2)) and cyclophosphamide (</= 6,300 mg/m(2)) for early breast cancer have a lower probability of secondary leukemia than patients treated with higher cumulative doses. Increased risk of secondary leukemia must be considered when assessing the potential benefit to risk ratio of higher than standard doses.

Aurora kinases A and B are up-regulated by Myc and are essential for maintenance of the malignant state

Myc oncoproteins promote continuous cell growth, in part by controlling the transcription of key cell cycle regulators. Here, we report that c-Myc regulates the expression of Aurora A and B kinases (Aurka and Aurkb), and that Aurka and Aurkb transcripts and protein levels are highly elevated in Myc-driven B-cell lymphomas in both mice and humans. The induction of Aurka by Myc is transcriptional and is directly mediated via E-boxes, whereas Aurkb is regulated indirectly. Blocking Aurka/b kinase activity with a selective Aurora kinase inhibitor triggers transient mitotic arrest, polyploidization, and apoptosis of Myc-induced lymphomas. These phenotypes are selectively bypassed by a kinase inhibitor-resistant Aurkb mutant, demonstrating that Aurkb is the primary therapeutic target in the context of Myc. Importantly, apoptosis provoked by Aurk inhibition was p53 independent, suggesting that Aurka/Aurkb inhibitors will show efficacy in treating primary or relapsed malignancies having Myc involvement and/or loss of p53 function.

Selection against PUMA gene expression in Myc-driven B-cell lymphomagenesis.

ABSTRACT The p53 tumor suppressor pathway limits oncogenesis by inducing cell cycle arrest or apoptosis. A key p53 target gene is PUMA, which encodes a BH3-only proapoptotic protein. Here we demonstrate that Puma deletion in the Eμ-Myc mouse model of Burkitt lymphoma accelerates lymphomagenesis and that ∼75% of Eμ-Myc lymphomas naturally select against Puma protein expression. Furthermore, approximately 40% of primary human Burkitt lymphomas fail to express detectable levels of PUMA and in some tumors this is associated with DNA methylation. Burkitt lymphoma cell lines phenocopy the primary tumors with respect to DNA methylation and diminished PUMA expression, which can be reactivated following inhibition of DNA methyltransferases. These findings establish that PUMA is silenced in human malignancies, and they suggest PUMA as a target for the development of novel chemotherapeutics.

Basoluminal Carcinoma: A New Biologically and Prognostically Distinct Entity Between Basal and Luminal Breast Cancer

Purpose: Breast carcinomas expressing basal epithelium cytokeratins constitute a tumor subgroup that is typically hormone receptor negative and shows a distinct gene expression profile. Based on variable basal cytokeratin immunostaining patterns, we hypothesized that the “basal phenotype” tumor group may comprise more than one biological entity. Experimental Design: Basal cytokeratins 5 and 14 (CK5/14) were stained by immunohistochemistry and the percentage of positive cells was defined by image analysis. The results thus obtained were compared with clinicopathologic characteristics and relapse-free survival. Results: Of the 506 breast tumors, 53 (10.5%) showed immunoreactivity for CK5/14. Basal cytokeratin expression showed up as two microscopically distinguishable subtypes, i.e., a uniformly positive type (“basal”) and a partially positive type (“basoluminal”) often displaying a checkerboard-type intratumoral heterogeneity. These subgroups could also be separated with a third basal cytokeratin (CK17, P < 0.0001). Both basal and basoluminal subtypes were hormone receptor negative and of high grade, but differed with respect to the Ki-67 labeling index (P = 0.0014), vimentin (P = 0.005), and c-kit (P = 0.02), which were more frequently expressed in basal than in basoluminal tumors. In contrast, the amplification of HER-2 was found almost exclusively in the basoluminal subgroup (P = 0.009). Compared with the basal tumors, basoluminal tumors associated with significantly shorter relapse-free survival (P = 0.01), which was not explained by their more frequent HER-2 amplification. Conclusions: We conclude that the intratumoral heterogeneity in basal cytokeratin expression can be used to define two distinct breast cancer subtypes, basal and basoluminal, with distinctive features related to proliferation activity, oncogene and biomarker status, and patient survival.

Therapeutic Implications for the Induced Levels of Chk1 in Myc-Expressing Cancer Cells

Purpose: The transcription factor c-Myc (or “Myc”) is a master regulator of pathways driving cell growth and proliferation. MYC is deregulated in many human cancers, making its downstream target genes attractive candidates for drug development. We report the unexpected finding that B-cell lymphomas from mice and patients exhibit a striking correlation between high levels of Myc and checkpoint kinase 1 (Chk1). Experimental Design: By in vitro cell biology studies as well as preclinical studies using a genetically engineered mouse model, we evaluated the role of Chk1 in Myc-overexpressing cells. Results: We show that Myc indirectly induces Chek1 transcript and protein expression, independently of DNA damage response proteins such as ATM and p53. Importantly, we show that inhibition of Chk1, by either RNA interference or a novel highly selective small molecule inhibitor, results in caspase-dependent apoptosis that affects Myc-overexpressing cells in both in vitro and in vivo mouse models of B-cell lymphoma. Conclusion: Our data suggest that Chk1 inhibitors should be further evaluated as potential drugs against Myc-driven malignancies such as certain B-cell lymphoma/leukemia, neuroblastoma, and some breast and lung cancers. Clin Cancer Res; 17(22); 7067–79. ©2011 AACR.

Is LRIG1 a tumour suppressor gene at chromosome 3p14.3

The LRIG1 gene (formerly LIG-1 ), recently cloned by us, displays structural similarities to the Drosophila Kek 1 gene. Kek 1 encodes a cell surface protein, Kekkon-1, which inhibits epidermal growth factor receptor-mediated signalling. We localized the LRIG1 gene to chromosome band 3p14.3, a region known to be deleted in various human cancers. In the present study LRIG1 gene expression was examined in different tumour cell lines and corresponding normal tissues by real-time RT-PCR. In many tumour cell lines, LRIG1 expression appeared absent or was down regulated compared to corresponding normal tissues. The results are consistent with LRIG1 being a tumour suppressor gene in humans. However, further studies are justified to elucidate the explicit role of LRIG1 as a negative regulator of oncogenesis.