Oncogenic translation directs spliceosome dynamics revealing an integral role for SF3A3 in breast cancer.

Splicing is a central RNA-based process commonly altered in human cancers; however, how spliceosomal components are co-opted during tumorigenesis remains poorly defined. Here we unravel the core splice factor SF3A3 at the nexus of a translation-based program that rewires splicing during malignant transformation. Upon MYC hyperactivation, SF3A3 levels are modulated translationally through an RNA stem-loop in an eIF3D-dependent manner. This ensures accurate splicing of mRNAs enriched for mitochondrial regulators. Altered SF3A3 translation leads to metabolic reprogramming and stem-like properties that fuel MYC tumorigenic potential in vivo. Our analysis reveals that SF3A3 protein levels predict molecular and phenotypic features of aggressive human breast cancers. These findings unveil a post-transcriptional interplay between splicing and translation that governs critical facets of MYC-driven oncogenesis.

Author Correction: Tertiary lymphoid structures improve immunotherapy and survival in melanoma.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Tertiary lymphoid structures improve immunotherapy and survival in melanoma.

Checkpoint blockade therapies that reactivate tumour-associated T cells can induce durable tumour control and result in the long-term survival of patients with advanced cancers1. Current predictive biomarkers for therapy response include high levels of intratumour immunological activity, a high tumour mutational burden and specific characteristics of the gut microbiota2,3. Although the role of T cells in antitumour responses has thoroughly been studied, other immune cells remain insufficiently explored. Here we use clinical samples of metastatic melanomas to investigate the role of B cells in antitumour responses, and find that the co-occurrence of tumour-associated CD8+ T cells and CD20+ B cells is associated with improved survival, independently of other clinical variables. Immunofluorescence staining of CXCR5 and CXCL13 in combination with CD20 reveals the formation of tertiary lymphoid structures in these CD8+CD20+ tumours. We derived a gene signature associated with tertiary lymphoid structures, which predicted clinical outcomes in cohorts of patients treated with immune checkpoint blockade. Furthermore, B-cell-rich tumours were accompanied by increased levels of TCF7+ naive and/or memory T cells. This was corroborated by digital spatial-profiling data, in which T cells in tumours without tertiary lymphoid structures had a dysfunctional molecular phenotype. Our results indicate that tertiary lymphoid structures have a key role in the immune microenvironment in melanoma, by conferring distinct T cell phenotypes. Therapeutic strategies to induce the formation of tertiary lymphoid structures should be explored to improve responses to cancer immunotherapy.

Molecular changes during progression from nonmuscle invasive to advanced urothelial carcinoma.

Molecular changes occurring during invasion and clinical progression of cancer are difficult to study longitudinally in patient-derived material. A unique feature of urothelial bladder cancer (UBC) is that patients frequently develop multiple nonmuscle invasive tumors, some of which may eventually progress to invade the muscle of the bladder wall. Here, we use a cohort of 73 patients that experienced a total of 357 UBC diagnoses to study the stability or change in detected molecular alterations during cancer progression. The tumors were subtyped by gene expression profiling and analyzed for hotspot mutations in FGFR3, PIK3CA and TERT, the most frequent early driver mutations in this tumor type. TP53 alterations, frequent in advanced UBC, were inferred from p53 staining pattern, and potential genomic alterations were inferred by gene expression patterns at regions harboring frequent copy number alterations. We show that early driver mutations were largely preserved in UBC recurrences. Changes in FGFR3, PIK3CA or TERT mutation status were not linked to changes in molecular subtype and aggressive behavior. Instead, changes into a more aggressive molecular subtype seem to be associated with p53 alterations. We analyze changes in gene expression from primary tumors, to recurrences and progression tumors, and identify two modes of progression: Patients for whom progression is preceded by or coincides with a radical subtype shift, and patients who progress without any systematic molecular changes. For the latter group of patients, progression may be either stochastic or depending on factors already present at primary tumor initiation.

Expression of epithelial-mesenchymal transition-related markers and phenotypes during breast cancer progression.

PURPOSE: The study aimed to investigate expression of epithelial-to-mesenchymal transition (EMT)-related proteins and phenotypes during breast cancer progression and to relate this to patient outcome. METHODS: Protein expression patterns of E-cadherin, N-cadherin, twist, and vimentin were examined by immunohistochemistry on formalin-fixed paraffin-embedded samples from primary tumors (PTs) (n = 419), synchronous lymph node metastases (LNMs) (n = 131) and recurrences (n = 34) from patients included in an observational prospective primary breast cancer study. Markers were evaluated individually and combined as defined EMT phenotypes (epithelial, mesenchymal, partial EMT, and negative). EMT profiles were compared between matched tumor progression stages, and related to clinicopathological data and distant recurrence-free interval (DRFi). RESULTS: N-cadherin-positivity, vimentin-positivity, mesenchymal and partial EMT phenotypes were associated with more aggressive tumor characteristics such as triple-negative subtype. Single EMT markers and phenotype discordance rates between paired tumor samples were observed in the range of 2-35%. Non-epithelial phenotypes were more frequently identified in recurrences compared to PTs, however, no skewness of expression or phenotype was detected between PTs and matched LNMs or between PTs and matched recurrences (Exact McNemar test). Interestingly, patients with a twist positive PT had shorter DRFi, compared to patients with a twist negative PT (hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.2-5.1, P = 0.02). Essentially, the same effect was seen in multivariable analysis (HR 2.5, 95% CI 0.97-6.6, P = 0.06). CONCLUSION: The epithelial phenotype was indicated to be lost between PTs and recurrences as a reflection of tumor progression. Twist status of the PT was related to long-term prognosis warranting further investigation in larger cohorts.

The estrogen receptor coactivator AIB1 is a new putative prognostic biomarker in ER-positive/HER2-negative invasive lobular carcinoma of the breast.

PURPOSE: According to the 2017 St Gallen surrogate definitions of the intrinsic subtypes, Ki67, progesterone receptor (PR) and Nottingham histological grade (NHG) are used for prognostic classification of estrogen receptor (ER) positive/HER2-negative breast cancer into luminal A- or luminal B-like. The aim of the present study was to investigate if additional biomarkers, related to endocrine signaling pathways, e.g., amplified in breast cancer 1 (AIB1), androgen receptor (AR), and G protein-coupled estrogen receptor (GPER), can provide complementary prognostic information in a subset of ER-positive/HER-negative invasive lobular carcinoma (ILC). METHODS: Biomarkers from 224 patients were analyzed immunohistochemically on tissue microarray. The primary endpoint was breast cancer mortality (BCM), analyzed with 10- and 25-year follow-up (FU). In addition, the prognostic value of gene expression data for these biomarkers was analyzed in three publicly available ILC datasets. RESULTS: AIB1 (high vs. low) was associated to BCM in multivariable analysis (adjusted for age, tumor size, nodal status, NHG, Ki67, luminal-like classification, and adjuvant systemic therapy) with 10-year FU (HR 6.8, 95% CI 2.3-20, P = 0.001) and 25-year FU (HR 3.0, 95% CI 1.1-7.8, P = 0.03). The evidence of a prognostic effect of AIB1 could be confirmed by linking gene expression data to outcome in independent publicly available ILC datasets. AR and GPER were neither associated to BCM with 10-year nor with 25-year FU (P > 0.33). Furthermore, Ki67 and NHG were prognostic for BCM at both 10-year and 25-year FU, whereas PR was not. CONCLUSIONS: AIB1 is a new putative prognostic biomarker in ER-positive/HER2-negative ILC.

Discordant molecular subtype classification in the basal-squamous subtype of bladder tumors and matched lymph-node metastases.

Molecular subtypes of muscle-invasive bladder tumors have emerged as a promising research tool with potential to stratify patients for neoadjuvant treatment. Prior to radical cystectomy, the utility of molecular classification and biomarkers depend on concordance between tissue from transurethrally resected specimens and disseminated disease. We assess the concordance of molecular subtypes and a large number of potential biomarkers in 67 pairs of muscle-invasive bladder tumors and synchronous lymph-node metastases. Tissue cores were stained for 29 immunohistochemistry markers and immunohistochemistry-based molecular subtype classification was performed. Molecular subtype was determined by mRNA profiling for 57 bladder tumors and 28 matched lymph-node metastases. Full section immunohistochemistry was performed to assess intra-tumor subtype heterogeneity in discordant cases, and exome sequencing was performed for 20 sample pairs. Discordant subtype classification between the bladder tumor and lymph-node metastasis was generally rare (12/67, 18%), but most (7/12, 58%) involved the Basal/Squamous-like subtype. Discordant Basal/Squamous-like tumors showed either Urothelial-like or Genomically Unstable, luminal-like phenotype in the lymph-node metastasis. Full section immunohistochemistry revealed intra-tumor subtype heterogeneity for six discordant cases including four involving the Basal/Squamous-like subtype. Subtype concordance for non- Basal/Squamous-like tumors was 91%. RNA-based classification agreed with immunohistochemistry classification but quantitative assessment is necessary to avoid false detection of subtype shifts. Most high confidence cancer mutations were shared between samples (n = 93, 78%), and bladder tumor private mutations (n = 20, 17%) were more frequent than those private to the lymph-node metastasis (n = 7, 6%). We conclude that bladder tumors and lymph-node metastases have overall similar molecular subtype, biomarker expression, and cancer mutations. The main exception was tumors of the Basal/Squamous-like subtype where most cases showed discordant classification, some with evidence of intra-tumor heterogeneity. The data are of relevance for neoadjuvant treatment stratification and raises questions on the dynamics of molecular subtypes during bladder cancer progression.

Toward a molecular pathologic classification of urothelial carcinoma.

We recently defined molecular subtypes of urothelial carcinomas according to whole genome gene expression. Herein we describe molecular pathologic characterization of the subtypes using 20 genes and IHC of 237 tumors. In addition to differences in expression levels, the subtypes show important differences in stratification of protein expression. The selected genes included biological features central to bladder cancer biology, eg, cell cycle activity, cellular architecture, cell-cell interactions, and key receptor tyrosine kinases. We show that the urobasal (Uro) A subtype shares features with normal urothelium such as keratin 5 (KRT5), P-cadherin (P-Cad), and epidermal growth factor receptor (EGFR) expression confined to basal cells, and cell cycle activity (CCNB1) restricted to the tumor-stroma interface. In contrast, the squamous cell cancer-like (SCCL) subtype uniformly expresses KRT5, P-Cad, EGFR, KRT14, and cell cycle genes throughout the tumor parenchyma. The genomically unstable subtype shows proliferation throughout the tumor parenchyma and high ERBB2 and E-Cad expression but absence of KRT5, P-Cad, and EGFR expression. UroB tumors demonstrate features shared by both UroA and SCCL subtypes. A major transition in tumor progression seems to be loss of dependency of stromal interaction for proliferation. We present a simple IHC/histology-based classifier that is easy to implement as a standard pathologic evaluation to differentiate the three major subtypes: urobasal, genomically unstable, and SCCL. These three major subtypes exhibit important prognostic differences.

Immunohistochemical assessment of Ki67 with antibodies SP6 and MIB1 in primary breast cancer: a comparison of prognostic value and reproducibility.

AIMS: To compare SP6 and MIB1 antibodies for assessment of Ki67 in primary breast cancer with regard to prognostic value and reproducibility. METHODS AND RESULTS: A cohort of 237 premenopausal women with node-negative breast cancer, mainly (87%) not treated with adjuvant systemic therapy, was used. Assessment of Ki67 (SP6 and MIB1) was performed on tissue microarray by three different investigators. The seventh decile was applied for cut-off. Distant disease-free survival (DDFS) was chosen as endpoint and the follow-up was restricted to 5 years. Eighty-nine per cent of the samples were classified into the same proliferation group, irrespective of antibody used. For both antibodies, high Ki67 was associated with inferior DDFS in univariable analyses (SP6: HR 2.5, P = 0.01; and MIB1: HR 2.8, P = 0.004), but failed to reach statistical significance for DDFS in multivariable analyses adjusted for HER2, age, and tumour size (SP6: HR 2.0, P = 0.074; and MIB1: HR 2.2, P = 0.058). The agreement between different assessors was somewhat higher for MIB1 than for SP6 (κ 0.83-0.88 versus 0.72-0.77). CONCLUSIONS: SP6 was not superior to MIB1, but the two antibodies were comparable in the assessment of Ki67. Both MIB1 and SP6 could therefore be considered for prognostic use in primary breast cancer.

Analysis of and prognostic information from disseminated tumour cells in bone marrow in primary breast cancer: a prospective observational study.

BACKGROUND: Disseminated tumour cells (DTCs) in the bone marrow of patients with breast cancer have been identified as an independent predictor of poor prognosis in patients with non-metastatic disease. This prospective study aimed to evaluate the presence and prognostic value of DTCs in the bone marrow of female patients with primary breast cancer. METHODS: Between 1999 and 2003, bone marrow aspirates were obtained from patients at the time of surgery for primary invasive breast cancer. DTCs in bone marrow were identified using monoclonal antibodies against cytokeratins for detection of epithelial cells. The detection of DTCs was related to clinical follow-up with distant disease-free survival (DDFS) and breast cancer-specific survival as endpoints. Bone marrow aspirates from adult healthy bone marrow donors were analysed separately. RESULTS: DTCs were analysed in 401 patients, and cytokeratin-positive cells were found in 152 of these (38%). An immunofluorescence (IF) staining procedure was used in 327 patients, and immunocytochemistry (IC) was performed in 74 patients. The IF-based method resulted in 40% DTC-positive cases, whereas 30% were positive using IC (p = 0.11). The presence of DTCs in bone marrow was not significantly related to patient or tumour characteristics. The presence of DTCs was not a prognostic factor for DDFS (IF: hazards ratio [HR], 2.2; 95% confidence interval [CI], 0.63-2.2; p = 0.60; IC: HR, 0.84; 95% CI, 0.09-8.1; p = 0.88). Significant prognostic factors were lymph node metastases, oestrogen receptor positivity, Nottingham histological grade, and tumour size using Cox univariate analysis. The analyses were positive for epithelial cells in bone marrow from adult healthy donors in 19 (25%) samples. CONCLUSIONS: The detection of DTCs in bone marrow in primary breast cancer was previously shown to be a predictor of poor prognosis. We were not able to confirm these results in a prospective cohort including unselected patients before the standard procedure was established. Future studies with a standardised patient protocol and improved technique for isolating and detecting DTCs may reveal the clinical applications of DTC detection in patients with micrometastases in the bone marrow.

The Prognostic Role of Intratumoral Stromal Content in Lobular Breast Cancer.

Previous studies have shown that high intratumoral stromal content is associated with a worse prognosis in breast cancer, especially in the triple-negative subtype. However, contradictory results have been reported for estrogen-receptor-positive (ER+) breast cancer, indicating that the prognostic role of intratumoral stromal content may be subtype-dependent. In this study, we investigated the importance of intratumoral stromal content for breast cancer-specific mortality (BCM) in a well-defined subgroup (n = 182) of ER+/human-epidermal growth-factor-receptor-2 negative (HER2-) invasive lobular breast cancer (ILC). The intratumoral stromal content was assessed on hematoxylin-eosin-stained whole sections and graded into high stroma (>50%) or low stroma (≤50%). A total of 82 (45%) patients had high-stroma tumors, and 100 (55%) had low-stroma tumors. High-stroma tumors were associated with a lower Nottingham histological grade, low Ki67, and a luminal A-like subtype. After a 10-year follow-up, the patients with high-stroma tumors had a lower BCM (HR: 0.43, 95% CI: 0.21-0.89, p = 0.023) in univariable analysis. Essentially the same effect was found in both the multivariable analysis (10-year follow-up) and univariable analysis (25-year follow-up), but these findings were not strictly significant. In ER+/HER2- ILC, high intratumoral stromal content is an easily assessable histological indicator of a good prognosis.

Different Responses to Neoadjuvant Chemotherapy in Urothelial Carcinoma Molecular Subtypes.

BACKGROUND: For muscle-invasive bladder cancer (MIBC), no tissue biomarkers are available for clinical use to predict response to neoadjuvant chemotherapy. OBJECTIVE: To investigate how molecular subtypes impact pathological response and survival in patients receiving preoperative cisplatin-based chemotherapy. DESIGN, SETTING, AND PARTICIPANTS: Classification of a retrospective cohort of 149 patients was performed by tumor transcriptomic profiling and immunostaining. A cohort treated with radical cystectomy alone and public data sets were used for comparison and external validation. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Complete pathological response in the cystectomy specimen (ypT0N0) and survival were compared in predefined molecular subtypes. Differential gene expression and chemotherapy response were explored beyond molecular subtypes. RESULTS AND LIMITATIONS: Patients with genomically unstable (GU) and urothelial-like (Uro) tumors had higher proportions of complete pathological response (16/31 [52%] and 17/54 [31%]), versus five out of 24 (21%) with the basal/squamous (Ba/Sq) subtype following neoadjuvant chemotherapy and radical cystectomy. Molecular subtype was independently associated with improved survival for patients with GU tumors (hazard ratio [HR] 0.29, 95% confidence interval [CI]: 0.11-0.79) and UroC tumors (HR 0.37, 95% CI: 0.14-0.94) compared with Ba/Sq tumors, adjusting for clinical stage. In addition, expression of the gene coding for osteopontin (SPP1) showed a subtype-dependent effect on chemotherapy response. CONCLUSIONS: Urothelial cancer of the luminal-like (GU and Uro) subtypes is more responsive to cisplatin-based neoadjuvant chemotherapy. A second-generation of subtype-specific biomarkers, for example, SPP1, may be a way forward to develop a more precision-based treatment approach for neoadjuvant chemotherapy in MIBC. PATIENT SUMMARY: This study shows that tumor classification by gene expression profiling and molecular subtyping can identify patients who are more likely to benefit from chemotherapy before radical cystectomy for muscle-invasive bladder cancer. Together with other markers for response, molecular subtypes could have a role in selective administration of such chemotherapy.

CD44 isoforms are heterogeneously expressed in breast cancer and correlate with tumor subtypes and cancer stem cell markers.

BACKGROUND: The CD44 cell adhesion molecule is aberrantly expressed in many breast tumors and has been implicated in the metastatic process as well as in the putative cancer stem cell (CSC) compartment. We aimed to investigate potential associations between alternatively spliced isoforms of CD44 and CSCs as well as to various breast cancer biomarkers and molecular subtypes. METHODS: We used q-RT-PCR and exon-exon spanning assays to analyze the expression of four alternatively spliced CD44 isoforms as well as the total expression of CD44 in 187 breast tumors and 13 cell lines. ALDH1 protein expression was determined by IHC on TMA. RESULTS: Breast cancer cell lines showed a heterogeneous expression pattern of the CD44 isoforms, which shifted considerably when cells were grown as mammospheres. Tumors characterized as positive for the CD44+/CD24- phenotype by immunohistochemistry were associated to all isoforms except the CD44 standard (CD44S) isoform, which lacks all variant exons. Conversely, tumors with strong expression of the CSC marker ALDH1 had elevated expression of CD44S. A high expression of the CD44v2-v10 isoform, which retain all variant exons, was correlated to positive steroid receptor status, low proliferation and luminal A subtype. The CD44v3-v10 isoform showed similar correlations, while high expression of CD44v8-v10 was correlated to positive EGFR, negative/low HER2 status and basal-like subtype. High expression of CD44S was associated with strong HER2 staining and also a subgroup of basal-like tumors. Unsupervised hierarchical cluster analysis of CD44 isoform expression data divided tumors into four main clusters, which showed significant correlations to molecular subtypes and differences in 10-year overall survival. CONCLUSIONS: We demonstrate that individual CD44 isoforms can be associated to different breast cancer subtypes and clinical markers such as HER2, ER and PgR, which suggests involvement of CD44 splice variants in specific oncogenic signaling pathways. Efforts to link CD44 to CSCs and tumor progression should consider the expression of various CD44 isoforms.

Can tissue microarray-based analysis of protein expression predict recurrence of stage Ta bladder cancer?

OBJECTIVE: Being able to predict the recurrence or progression of non-muscle-invasive bladder cancer would facilitate effective planning of treatments and follow-up. Biomarkers are needed that can supply prognostic information beyond that provided by clinical and pathological parameters. Tissue microarray (TMA)-based analysis of Ta bladder tumours was used to investigate the prognostic value of expression of several proteins involved in bladder carcinogenesis. MATERIAL AND METHODS: Tumour tissue from 52 patients with Ta bladder cancer was investigated. At least three 0.6 mm punch cores from each tumour were placed in a paraffin array block. Tumour expression of tumour protein 53 (TP53), CDH1 (E-cadherin), proliferating cell nuclear antigen (PCNA), cyclooxygenase-2 (COX2), fibroblast growth factor receptor-3 (FGFR3) and epidermal growth factor receptor (EGFR) was quantified by immunohistochemistry (IHC) and correlated with time to recurrence. Median follow-up time was 3.1 years. Whole-section IHC analysis was performed to validate significant findings. RESULTS: Of all patients, 69% (36/52) experienced recurrence. In univariate analysis, recurrence was associated with multifocality, number of earlier recurrences and a low quantity score for EGFR. In a multivariate model, a low EGFR quantity score was correlated with early recurrence (hazard ratio = 5.5, p = 0.003). However, whole-section IHC results for EGFR differed markedly from the TMA findings (κ = 0.07) and no association with time to recurrence was found (p = 0.65). CONCLUSIONS: Expression of EGFR measured by TMA-IHC, but not by whole-section IHC, was associated with early recurrence. The results suggest that the proteins assessed have no predictive value for recurrences. Concerns are raised regarding the methodology and generalization of results obtained with TMA-IHC.

The prognostic value of Ki67 is dependent on estrogen receptor status and histological grade in premenopausal patients with node-negative breast cancer.

The aim of this study was to evaluate the prognostic value of Ki67 in relation to established prognostic factors in lymph node-negative breast cancer, and furthermore, whether the prognostic impact was dependent on estrogen receptor (ER) status and histological grade. In 200 premenopausal patients, with 5 years of follow-up, Ki67 was determined on tissue microarrays. In univariate analysis, Ki67 (< or = 20 vs >20%) was a prognostic factor for distant disease-free survival (hazard ratio: 2.7, 95% confidence interval: 1.3-5.4, P=0.005) and overall survival (hazard ratio: 4.9, 95% confidence interval: 1.7-14, P=0.003). When stratifying for ER status and histological grade, Ki67 was a significant prognostic factor for distant disease-free survival and overall survival only in the ER-positive group, and only in patients with histological grade 2, respectively. In multivariate analysis, human epidermal growth factor receptor 2 and age were independent prognostic factors for distant disease-free survival, whereas Ki67, histological grade, and tumor size were not. Ki67 was, however, an independent prognostic factor in the 87% of the patients who had not received adjuvant medical treatment. Agreement between the three readers was very good (kappa-values: 0.83-0.88). Furthermore, Ki67 was a significant prognostic factor for all three investigators (hazard ratio: 2.7-3.2). This study shows that Ki67 is a prognostic factor in node-negative breast cancer. It is noteworthy that the prognostic information of Ki67 is restricted to ER-positive patients, and to patients with histological grade 2. Taken together, Ki67, as an easily assessed and reproducible proliferation factor, may be an alternative or complement to histological grade as a prognostic tool and for selection of adjuvant treatment.

Up-regulation of cell cycle arrest protein BTG2 correlates with increased overall survival in breast cancer, as detected by immunohistochemistry using tissue microarray.

BACKGROUND: Previous studies have shown that the ADIPOR1, ADORA1, BTG2 and CD46 genes differ significantly between long-term survivors of breast cancer and deceased patients, both in levels of gene expression and DNA copy numbers. The aim of this study was to characterize the expression of the corresponding proteins in breast carcinoma and to determine their correlation with clinical outcome. METHODS: Protein expression was evaluated using immunohistochemistry in an independent breast cancer cohort of 144 samples represented on tissue microarrays. Fisher's exact test was used to analyze the differences in protein expression between dead and alive patients. We used Cox-regression multivariate analysis to assess whether the new markers predict the survival status of the patients better than the currently used markers. RESULTS: BTG2 expression was demonstrated in a significantly lower proportion of samples from dead patients compared to alive patients, both in overall expression (P = 0.026) and cell membrane specific expression (P = 0.013), whereas neither ADIPOR1, ADORA1 nor CD46 showed differential expression in the two survival groups. Furthermore, a multivariate analysis showed that a model containing BTG2 expression in combination with HER2 and Ki67 expression along with patient age performed better than a model containing the currently used prognostic markers (tumour size, nodal status, HER2 expression, hormone receptor status, histological grade, and patient age). Interestingly, BTG2 has previously been described as a tumour suppressor gene involved in cell cycle arrest and p53 signalling. CONCLUSIONS: We conclude that high-level BTG2 protein expression correlates with prolonged survival in patients with breast carcinoma.

The Role of PTEN Loss in Immune Escape, Melanoma Prognosis and Therapy Response.

Checkpoint blockade therapies have changed the clinical management of metastatic melanoma patients considerably, showing survival benefits. Despite the clinical success, not all patients respond to treatment or they develop resistance. Although there are several treatment predictive biomarkers, understanding therapy resistance and the mechanisms of tumor immune evasion is crucial to increase the frequency of patients benefiting from treatment. The PTEN gene is thought to promote immune evasion and is frequently mutated in cancer and melanoma. Another feature of melanoma tumors that may affect the capacity of escaping T-cell recognition is melanoma cell dedifferentiation characterized by decreased expression of the microphtalmia-associated transcription factor (MITF) gene. In this study, we have explored the role of PTEN in prognosis, therapy response, and immune escape in the context of MITF expression using immunostaining and genomic data from a large cohort of metastatic melanoma. We confirmed in our cohort that PTEN alterations promote immune evasion highlighted by decreased frequency of T-cell infiltration in such tumors, resulting in a worse patient survival. More importantly, our results suggest that dedifferentiated PTEN negative melanoma tumors have poor patient outcome, no T-cell infiltration, and transcriptional properties rendering them resistant to targeted- and immuno-therapy.

The CD44+/CD24- phenotype is enriched in basal-like breast tumors.

INTRODUCTION: Human breast tumors are heterogeneous and consist of phenotypically diverse cells. Breast cancer cells with a CD44+/CD24- phenotype have been suggested to have tumor-initiating properties with stem cell-like and invasive features, although it is unclear whether their presence within a tumor has clinical implications. There is also a large heterogeneity between tumors, illustrated by reproducible stratification into various subtypes based on gene expression profiles or histopathological features. We have explored the prevalence of cells with different CD44/CD24 phenotypes within breast cancer subtypes. METHODS: Double-staining immunohistochemistry was used to quantify CD44 and CD24 expression in 240 human breast tumors for which information on other tumor markers and clinical characteristics was available. Gene expression data were also accessible for a cohort of the material. RESULTS: A considerable heterogeneity in CD44 and CD24 expression was seen both between and within tumors. A complete lack of both proteins was evident in 35% of the tumors, while 13% contained cells of more than one of the CD44+/CD24-, CD44-/CD24+ and CD44+/CD24+ phenotypes. CD44+/CD24- cells were detected in 31% of the tumors, ranging in proportion from only a few to close to 100% of tumor cells. The CD44+/CD24- phenotype was most common in the basal-like subgroup--characterized as negative for the estrogen and progesterone receptors as well as for HER2, and as positive for cytokeratin 5/14 and/or epidermal growth factor receptor, and particularly common in BRCA1 hereditary tumors, of which 94% contained CD44+/CD24- cells. The CD44+/CD24- phenotype was surprisingly scarce in HER2+ tumors, which had a predominantly CD24+ status. A CD44+/CD24- gene expression signature was generated, which included CD44 and alpha6-integrin (CD49f) among the top-ranked overexpressed genes. CONCLUSION: We demonstrate an association between basal-like and particularly BRCA1 hereditary breast cancer and the presence of CD44+/CD24- cells. Not all basal-like tumors and very few HER2+ tumors, however, contain CD44+/CD24- cells, emphasizing that a putative tumorigenic ability may not be confined to cells of this phenotype and that other breast cancer stem cell markers remain to be identified.

Tissue microarray based analysis of prognostic markers in invasive bladder cancer: much effort to no avail?

PURPOSE: To evaluate altered protein expression with tissue microarray methodology for 15 different markers with potential prognostic significance in invasive bladder cancer. MATERIALS AND METHODS: Invasive tumor was sampled with the tissue-arraying instrument in 133 consecutive patients who underwent radical cystectomy, and at least 3, 0.6-mm tissue cores were obtained. With immunohistochemistry, the expressions of TP53, RB1, CDKN1A (p21), MKI67 (Ki67), PTGS2 (Cox-2), CTNNA1 (alpha-catenin), CTNNB1 (beta-catenin), AKT, PTEN, RHOA, RHOC, STAT1, VEGFC, EGFR, and ERBB2 (HER2) were quantified, and correlations were made with tumor grade, pathologic stage, lymph node status, and disease-specific survival. RESULTS: Decreased immunohistochemical expression of CTNNA1 and of PTEN correlated with higher pathologic tumor stages (P = 0.01 and P = 0.01, respectively), whereas increased AKT1 and ERBB2 correlated with lower pathologic tumor stages (P = 0.01 and P = 0.03, respectively). Increased RHOA expression was more common in grade 3 than in grade 2 tumors (P = 0.016). There were no other correlations among the 15 factors studied and pathologic stage, lymph node status, or tumor grade. No association was found between bladder cancer death and altered marker status for any of the markers studied. CONCLUSIONS: Currently, there are reasons to have a skeptical attitude toward the value of tissue microarray based immunohistochemistry as a method for evaluating prognostic markers in invasive bladder cancer. In this study, 15 antibodies were tested but were found to be of little clinical value. Whether this negative finding is related to the group of patients or factors studied, or the methodology is unclear.

Prior Adjuvant Tamoxifen Treatment in Breast Cancer Is Linked to Increased AIB1 and HER2 Expression in Metachronous Contralateral Breast Cancer.

AIM: The estrogen receptor coactivator Amplified in Breast Cancer 1 (AIB1) has been associated with an improved response to adjuvant tamoxifen in breast cancer, but also with endocrine treatment resistance. We hereby use metachronous contralateral breast cancer (CBC) developed despite prior adjuvant tamoxifen for the first tumor as an "in vivo"-model for tamoxifen resistance. AIB1-expression in the presumable resistant (CBC after prior tamoxifen) and naïve setting (CBC without prior tamoxifen) is compared and correlated to prognosis after CBC. METHODS: From a well-defined population-based cohort of CBC-patients we have constructed a unique tissue-microarray including >700 patients. RESULTS: CBC developed after adjuvant tamoxifen more often had a HER2-positive/triple negative-subtype and a high AIB1-expression (37% vs. 23%, p = 0.009), than if no prior endocrine treatment had been administered. In patients with an estrogen receptor (ER) positive CBC, a high AIB1-expression correlated to an inferior prognosis. However, these patients seemed to respond to tamoxifen, but only if endocrine therapy had not been administered for BC1. CONCLUSIONS: Metachronous CBC developed after prior endocrine treatment has a decreased ER-expression and an increased HER2-expression. This is consistent with endocrine treatment escape mechanisms previously suggested, and indicates metachronous CBC to be a putative model for studies of treatment resistance "in vivo". The increased AIB1-expression in CBC developed after prior tamoxifen suggests a role of AIB1 in endocrine treatment resistance. In addition, we found indications that the response to tamoxifen in CBC with a high AIB1-expression seem to differ depending on previous exposure to this drug. A different function for AIB1 in the tamoxifen treatment naïve vs. resistant setting is suggested, and may explain previously conflicting results where a high AIB1-expression has been correlated to both a good response to adjuvant tamoxifen and tamoxifen resistance.