Hawa Nalwoga

Frequency of the basal-like phenotype in African breast cancer

Basal‐like breast carcinoma has been recognized as a subtype with specific prognostic implications. However, there is a lack of reports about this category of breast tumors in African women. The aim of this study was to explore the basal‐like phenotype in breast cancer patients in an African population, and a registry‐based series was included from the well‐defined Kyadondo County in Uganda (1.7 millions). We studied a total of 65 archival paraffin blocks of invasive breast cancer using antibodies against cytokeratin 5/6 and P‐cadherin, and these markers were expressed in 34% of all cases and in 52% of ER (estrogen receptor)‐negative tumors. All basal‐like tumors were ER negative (p<0.0005) and PR (progesterone receptor) negative (p=0.002). Basal‐like breast carcinomas were of a higher histologic grade (p=0.001), had high mitotic counts (p=0.002), and marked nuclear pleomorphism (p=0.002). P‐cadherin‐positive tumors had a high Ki‐67 proliferative rate (p=0.039). In conclusion, the basal‐like phenotype is frequent in this African series of breast cancer and is strongly associated with poor prognostic factors. Our findings might be significant in relation to clinical management of these patients, including novel targeted therapy.

Expression of EGFR and c-kit is associated with the basal-like phenotype in breast carcinomas of African women

Epidermal growth factor receptor (EGFR) and c‐kit are tyrosine kinase growth factor receptors which are frequently expressed in basal‐like breast carcinomas, and tyrosine kinase inhibition is now a promising strategy in treatment of breast cancer. The aim of this study was to evaluate the expression of EGFR and c‐kit in breast cancer with special focus on the basal‐like phenotype (BLP) and other prognostic factors in an African population. We analyzed 65 archival tissues immunohistologically. EGFR and/or c‐kit were expressed in 55% of basal‐like tumors. Expression of EGFR and/or c‐kit was strongly associated with high histologic grade (P=0.001), high nuclear grade (P=0.017), high mitotic counts (P=0.002), ER negativity (P=0.003), PR negativity (P=0.007), and HER2 negativity (P=0.014). EGFR and/or c‐kit positive tumors were more likely to express the BLP (OR 9.1, CI 2.6–32.0, P<0.0005) than the negative tumors. In conclusion, there is a high expression of EGFR and/or c‐kit in basal‐like breast carcinoma in this series from Uganda and their expression is associated with features of poor prognosis. More studies are required to assess the clinical significance of EGFR and c‐kit in breast cancer patients in Uganda.

Decreased Serum Opsonic Activity against Streptococcus pneumoniae in Human Immunodeficiency Virus—Infected Ugandan Adults

Type-specific immunoglobulin G (IgG) to pneumococcal capsular polysaccharide (CPS) and opsonic activity against Streptococcus pneumoniae were evaluated in serum samples from 36 Ugandan adults with community-acquired pneumonia and 58 asymptomatic Ugandan adults with or without human immunodeficiency virus type 1 (HIV-1) infection. The levels of serum IgG to CPS were significantly higher in HIV-1-infected subjects than in HIV-uninfected subjects. Serum samples from HIV-1-infected subjects that had lower IgG titers demonstrated higher opsonic activity against type 3 (titers of 7) and type 9 (titers of 7-11) pneumococcal strains. Plasma HIV-1 load also correlated inversely with serum opsonic activity against these strains, and peripheral blood CD4+ lymphocyte numbers also tended to correlate with serum opsonic activity in asymptomatic HIV-1-infected adults. Our findings suggest that the opsonic activity of type-specific IgG is impaired in the serum of HIV-1-infected African adults, which may expose them to a serious risk of invasive pneumococcal infections.

In vivo MRI and histopathological assessment of tumor microenvironment in luminal-like and basal-like breast cancer xenografts

To explore tumor pathophysiology with special attention to the microenvironment in two molecular subtypes of human breast cancer using in vivo magnetic resonance imaging (MRI) and histopathology. The impact of tumor growth, size, and the influence of estradiol were also investigated.

GRK3 is essential for metastatic cells and promotes prostate tumor progression

Significance Although the majority of cancer-related deaths are consequences of metastatic dissemination, the molecular and cellular forces that drive tumor cell dispersion are still poorly understood. To help identify new regulators that play critical roles in these processes, we screened for human kinases that are important for continued survival of metastatic cells. One kinase identified from these screens, the G-protein–coupled receptor kinase 3 (GRK3; or β-adrenergic receptor kinase 2), was found to have a key role in promoting prostate tumor growth and metastasis in mouse models through enhancing angiogenesis. Notably, GRK3 is overexpressed in human prostate metastatic tumors. Further studies on GRK3 and its pathways promise to expand our knowledge of cancer metastasis and also yield new cancer therapeutic targets. The biochemical mechanisms that regulate the process of cancer metastasis are still poorly understood. Because kinases, and the signaling pathways they comprise, play key roles in regulation of many cellular processes, we used an unbiased RNAi in vitro screen and a focused cDNA in vivo screen against human kinases to identify those with previously undocumented roles in metastasis. We discovered that G-protein–coupled receptor kinase 3 (GRK3; or β-adrenergic receptor kinase 2) was not only necessary for survival and proliferation of metastatic cells, but also sufficient to promote primary prostate tumor growth and metastasis upon exogenous expression in poorly metastatic cells in mouse xenograft models. Mechanistically, we found that GRK3 stimulated angiogenesis, at least in part through down-regulation of thrombospondin-1 and plasminogen activator inhibitor type 2. Furthermore, GRK3 was found to be overexpressed in human prostate cancers, especially in metastatic tumors. Taken together, these data suggest that GRK3 plays an important role in prostate cancer progression and metastasis.

Effect of antiangiogenic therapy on tumor growth, vasculature and kinase activity in basal- and luminal-like breast cancer xenografts

Several clinical trials have investigated the efficacy of bevacizumab in breast cancer, and even if growth inhibiting effects have been registered when antiangiogenic treatment is given in combination with chemotherapy no gain in overall survival has been observed. One reason for the lack of overall survival benefit might be that appropriate criteria for selection of patients likely to respond to antiangiogenic therapy in combination with chemotherapy, are not available.

Strong Expression of Hypoxia-Inducible Factor-1α (HIF-1α) Is Associated with Axl Expression and Features of Aggressive Tumors in African Breast Cancer.

Purpose Inhibition of hypoxia-inducible factor (HIF) and Axl receptor tyrosine kinase is being evaluated for targeted therapy in solid tumors. Both HIF-1α and Axl influence tumor growth and metastatic potential, and they have been linked to treatment failure in many cancers. However, there is a lack of reports on HIF-1α expression in African breast cancer, which has a poor prognosis, and novel treatment targets must therefore be established. Here, we aimed to evaluate HIF-1α in relation to Axl expression, angiogenesis markers, and other tumor characteristics in a series of African breast cancer. Methods Using immunohistochemistry, we examined 261 invasive breast cancers on tissue microarrays for HIF-1α and Axl as well as several other markers, and a subset of 185 cases had information on VEGF (vascular endothelial growth factor) expression, microvessel density (MVD), proliferating microvessel density (pMVD) and vascular proliferation index (VPI) for important comparisons. Results Strong HIF-1α expression was associated with increased Axl (p = 0.007), VEGF (p<0.0005), and p53 (p = 0.032) expression, as well as high tumor cell proliferation by Ki-67 (p = 0.006), and high tumor grade (p = 0.003). Tumors with strong HIF-1α expression had significantly higher MVD (p = 0.019) and higher pMVD (p = 0.027) than tumors with weak expression. Conclusions High HIF-1α expression is significantly associated with Axl and VEGF expression, and with markers of poor prognosis in this series of breast cancer, suggesting HIF-1α and Axl as potential therapeutic targets in African breast cancer.

Increased tumor cell expression of Axl is a marker of aggressive features in breast cancer among African women

Axl, a receptor tyrosine kinase belonging to the Tyro/Axl/Mer (TAM) family, has been shown to be overexpressed in breast cancer with poor outcome. Moreover, Axl was associated with a basal‐like phenotype (BLP) in these tumors. Our aim was to investigate Axl expression in breast cancers from an African population since these tumors are known to be aggressive and have a high frequency of the basal‐like phenotype. We studied 170 paraffin‐embedded breast carcinoma cases by tissue microarrays and immunohistochemical methods. In total, 128 tumor cases (75%) had strong Axl expression and 42 cases (25%) had weak or negative staining. Strong expression of Axl was associated with high tumor grade (p < 0.0005), estrogen receptor (ER) negativity (p = 0.024), p53 expression (p = 0.004), P‐cadherin positivity (p = 0.017), and basal‐like phenotypic profiles BLP2 (p = 0.033) and BLP3 (p = 0.022). In addition, Axl overexpression also showed an association with markers of tumor cell proliferation and tumor angiogenesis. In conclusion, our findings indicate strong expression of Axl in a high proportion of breast cancer cases among African women and associations with markers of aggressive features, indicating poor prognosis. These findings suggest Axl as a potential therapeutic target in this population.

Expression of Nestin associates with BRCA1 mutations, a basal-like phenotype and aggressive breast cancer

We here examined whether Nestin, by protein and mRNA levels, could be a predictor of BRCA1 related breast cancer, a basal-like phenotype, and aggressive tumours. Immunohistochemical staining of Nestin was done in independent breast cancer hospital cohorts (Series I-V, total 1257 cases). Also, TCGA proteomic data (n = 103), mRNA microarray data from TCGA (n = 520), METABRIC (n = 1992), and 6 open access breast cancer datasets (n = 1908) were analysed. Patients with Nestin protein expression in tumour cells more often had BRCA1 germline mutations (OR 8.7, p < 0.0005, Series III), especially among younger patients (<40 years at diagnosis) (OR 16.5, p = 0.003). Nestin protein positivity, observed in 9–28% of our hospital cases (Series I-IV), was independently associated with reduced breast cancer specific survival (HR = 2.0, p = 0.035) and was consistently related to basal-like differentiation (by Cytokeratin 5, OR 8.7–13.8, p < 0.0005; P-cadherin OR 7.0–8.9, p < 0.0005; EGFR staining, OR 3.7–8.2, p ≤ 0.05). Nestin mRNA correlated significantly with Nestin protein expression (ρ = 0.6, p < 0.0005), and high levels were seen in the basal-like intrinsic subtype. Gene expression signalling pathways linked to high Nestin were explored, and revealed associations with stem-like tumour features. In summary, Nestin was strongly associated with germline BRCA1 related breast cancer, a basal-like phenotype, reduced survival, and stemness characteristics.

Abstract 2429: Nestin expression in tumor cells is associated with BRCA1 positive genotype and a basal-like phenotype in breast cancer

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: The basal-like subtype of breast cancer is one of at least five molecular categories. These poor prognosis tumors are most often triple negative, i.e. negative for hormone receptors and HER2, and therefore lack targeted treatment options. There is at present no consensus on how to best define this subtype, and different surrogate immunohistochemistry based markers have been suggested. We here present data supporting nestin as a marker of the basal-like subtype. Originally reported in neuronal progenitor cells, nestin was later observed in the stem cell/progenitor compartment in a variety of tissues as well as in different cancer types, and suggested to be a cancer stem cell marker. In breast cancer, nestin has been reported in the basal-like and triple negative phenotypes. Here, we examined nestin expression in different breast cancer cohorts, including BRCA familial cancer, and breast cancer metastasis. Materials and methods: Immunohistochemical staining of nestin was done in four series of breast cancer, and a semi-quantitative measure of nestin positivity (staining index) was used for evaluation of expression. Series I include 190 breast cancer patients diagnosed during 1996-2001 in Hordaland, Norway. Series II comprise 192 breast cancer cases identified in Kampala, Uganda in 1990-2002. Series III includes 151 patients with breast cancer, 53 BRCA1 and 45 BRCA2 mutation carriers, identified during 1980-1995 in Montreal, Canada, and 51 BRCA negative patients from Norway. Series IV consists of 35 patients with tissue from the primary breast cancer and matched metastasis collected in 1996-2007. Finally, level 3 mRNA microarray data from TCGA (n = 520) and four open access breast cancer gene expression data sets (n = 1148) with information on molecular subtype were included. Results: The proportion of nestin positive breast tumors was 11%, 24% and 28% in Series I-III. Nestin expression was significantly associated with basal cell markers Cytokeratin 5/6 and P-cadherin (p-values <0.0005), five immunohistochemical profiles for the basal-like phenotype (Odds ratio, OR, range 10.9-27.5) and the triple negative phenotype (OR range 11.8-28.2). Further, patients with BRCA1 mutation more often had nestin positive tumors (OR 8.7, Series III). Higher nestin mRNA levels were seen in basal-like tumors, compared with the luminal-like and HER2-enriched subtypes. In Series IV, nestin expression in the primary tumor correlated with expression in the corresponding metastasis, with no statistically significant difference between the two groups (McNemar test, p = 1.0). Conclusion: We found nestin positivity in breast cancer cells to be significantly and strongly associated with the BRCA1 genotype, individual basal cell markers, and the basal-like and triple negative phenotypes. Citation Format: Kristi Kruger, Elisabeth Wik, Hawa Nalwoga, Monica Mannelqvist, Ingunn M. Stefansson, Jarle B. Arnes, Goril Knutsvik, Turid Aas, William D. Foulkes, Lars A. Akslen. Nestin expression in tumor cells is associated with BRCA1 positive genotype and a basal-like phenotype in breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2429. doi:10.1158/1538-7445.AM2015-2429