FGFR­related phenotypic and functional profile of CAFs in prognostication of breast cancer (Review).

While preclinical studies consistently implicate FGFR­signalling in breast cancer (BC) progression, clinical evidence fails to support these findings. It may be that the clinical significance of FGFR ought to be analysed in the context of the stroma, activating or repressing its function. The present review aimed to provide such a context by summarizing the existing data on the prognostic and/or predictive value of selected cancer­associated fibroblasts (CAFs)­related factors, that either directly or indirectly may affect FGFR­signalling. PubMed (https://pubmed.ncbi.nlm.nih.gov/) and Medline (https://www.nlm.nih.gov/medline/medline_home.html) databases were searched for the relevant literature related to the prognostic and/or predictive significance of: CAFs phenotypic markers (αSMA, S100A4/FSP­1, PDGFR, PDPN and FAP), CAFs­derived cognate FGFR ligands (FGF2, FGF5 and FGF17) or inducers of CAFs' paracrine activity (TGF­ß1, HDGF, PDGF, CXCL8, CCL5, CCL2, IL­6, HH and EGF) both expressed in the tumour and circulating in the blood. A total of 68 articles were selected and thoroughly analysed. The findings consistently identified upregulation of αSMA, S100A4/FSP­1, PDGFR, PDPN, HDGF, PDGF, CXCL8, CCL5, CCL2, IL­6, HH and EGF as poor prognostic markers in BC, while evaluation of the prognostic value of the remaining markers varied between the studies. The data confirm an association of CAFs­specific features with BC prognosis, suggesting that both quantitative and qualitative profiling of the stroma might be required for an assessment of the true FGFR's clinical value.

FGFR2-triggered autophagy and activation of Nrf-2 reduce breast cancer cell response to anti-ER drugs.

BACKGROUND: Genetic abnormalities in the FGFR signalling occur in 40% of breast cancer (BCa) patients resistant to anti-ER therapy, which emphasizes the potential of FGFR-targeting strategies. Recent findings indicate that not only mutated FGFR is a driver of tumour progression but co-mutational landscapes and other markers should be also investigated. Autophagy has been recognized as one of the major mechanisms underlying the role of tumour microenvironment in promotion of cancer cell survival, and resistance to anti-ER drugs. The selective autophagy receptor p62/SQSTM1 promotes Nrf-2 activation by Keap1/Nrf-2 complex dissociation. Herein, we have analysed whether the negative effect of FGFR2 on BCa cell response to anti-ER treatment involves the autophagy process and/or p62/Keap1/Nrf-2 axis. METHODS: The activity of autophagy in ER-positive MCF7 and T47D BCa cell lines was determined by analysis of expression level of autophagy markers (p62 and LC3B) and monitoring of autophagosomes' maturation. Western blot, qPCR and proximity ligation assay were used to determine the Keap1/Nrf-2 interaction and Nrf-2 activation. Analysis of 3D cell growth in Matrigel® was used to assess BCa cell response to applied treatments. In silico gene expression analysis was performed to determine FGFR2/Nrf-2 prognostic value. RESULTS: We have found that FGFR2 signalling induced autophagy in AMPKα/ULK1-dependent manner. FGFR2 activity promoted dissociation of Keap1/Nrf-2 complex and activation of Nrf-2. Both, FGFR2-dependent autophagy and activation of Nrf-2 were found to counteract the effect of anti-ER drugs on BCa cell growth. Moreover, in silico analysis showed that high expression of NFE2L2 (gene encoding Nrf-2) combined with high FGFR2 expression was associated with poor relapse-free survival (RFS) of ER+ BCa patients. CONCLUSIONS: This study revealed the unknown role of FGFR2 signalling in activation of autophagy and regulation of the p62/Keap1/Nrf-2 interdependence, which has a negative impact on the response of ER+ BCa cells to anti-ER therapies. The data from in silico analyses suggest that expression of Nrf-2 could act as a marker indicating potential benefits of implementation of anti-FGFR therapy in patients with ER+ BCa, in particular, when used in combination with anti-ER drugs.

FGFR4-driven plasticity in breast cancer progression and resistance to therapy.

Breast cancer (BCa) is a complex and heterogeneous disease, with different intrinsic molecular subtypes that have distinct clinical outcomes and responses to therapy. Although intrinsic subtyping provides guidance for treatment decisions, it is now widely recognised that, in some cases, the switch of the BCa intrinsic subtype (which embodies cellular plasticity), may be responsible for therapy failure and disease progression. Aberrant FGFR4 signalling has been implicated in various cancers, including BCa, where it had been shown to be associated with aggressive subtypes, such as HER2-enriched BCa, and poor prognosis. More importantly, FGFR4 is also emerging as a potential driver of BCa intrinsic subtype switching, and an essential promoter of brain metastases, particularly in the HER2-positive BCa. Although the available data are still limited, the findings may have far-reaching clinical implications. Here, we provide an updated summary of the existing both pre- and clinical studies of the role of FGFR4 in BCa, with a special focus on its contribution to subtype switching during metastatic spread and/or induced by therapy. We also discuss a potential clinical benefit of targeting FGFR4 in the development of new treatment strategies.

FGF7/FGFR2-JunB signalling counteracts the effect of progesterone in luminal breast cancer.

We have recently demonstrated that fibroblast growth factor receptor 2 (FGFR2)-mediated signalling alters progesterone receptor (PR) activity and response of oestrogen receptor α (ER)-positive (ER+) breast cancer (BCa) cell lines to anti-ER agents. Little is known about whether the crosstalk between ER and PR, shown to be modulated by the hormonal background, might also be affected by FGFR2. Here, PR-dependent behaviour of ER+ BCa cells was studied in the presence of oestrogen (E2) and progesterone (P4) and/or FGF7. In vitro analyses showed that FGF7/FGFR2 signalling: (a) abolished the effect of P4 on E2-promoted 3D cell growth and response to tamoxifen; (b) regulated ER and PR expression and activity; (c) increased formation of ER-PR complexes; and (d) reversed P4-triggered deregulation of ER-dependent genes. Analysis of clinical data demonstrated that the prognostic value of FGFR2 varied between patients with different menopausal status; that is, high expression of FGFR2 was significantly associated with longer progression-free survival (PFS) in postmenopausal patients, whereas there was no significant association in premenopausal patients. FGFR2 was found to positively correlate with the expression of JunB proto-oncogene, AP-1 transcription factor subunit (JUNB), an ER-dependent gene, only in premenopausal patients. Molecular analyses revealed that the presence of JunB was a prerequisite for FGFR2-mediated abrogation of P4-induced inhibition of cell growth. Our results demonstrate for the first time that the FGF7/FGFR2-JunB axis abolishes the modulatory effects of PR on ER-associated biological functions in premenopausal ER+ BCa. This may provide foundations for a better selection of patients for FGFR-targeting therapeutic strategies.

Subtype-Specific Tumour Immune Microenvironment in Risk of Recurrence of Ductal Carcinoma In Situ: Prognostic Value of HER2.

Increasing evidence suggests that the significance of the tumour immune microenvironment (TIME) for disease prognostication in invasive breast carcinoma is subtype-specific but equivalent studies in ductal carcinoma in situ (DCIS) are limited. The purpose of this paper is to review the existing data on immune cell composition in DCIS in relation to the clinicopathological features and molecular subtype of the lesion. We discuss the value of infiltration by various types of immune cells and the PD-1/PD-L1 axis as potential markers of the risk of recurrence. Analysis of the literature available in PubMed and Medline databases overwhelmingly supports an association between densities of infiltrating immune cells, traits of immune exhaustion, the foci of microinvasion, and overexpression of HER2. Moreover, in several studies, the density of immune infiltration was found to be predictive of local recurrence as either in situ or invasive cancer in HER2-positive or ER-negative DCIS. In light of the recently reported first randomized DCIS trial, relating recurrence risk with overexpression of HER2, we also include a closing paragraph compiling the latest mechanistic data on a functional link between HER2 and the density/composition of TIME in relation to its potential value in the prognostication of the risk of recurrence.

Liver metastasis or a pseudocyst? A rare presentation of leiomyosarcoma's metastasis in the liver.

Gastrointestinal neoplasms most commonly metastasize to the liver, where they are typically found as solid and hypervascular lesions. Here, we describe a case of a 44-year-old man with a leiomyosarcoma of the rectum, who at the time of diagnosis presented with a small (5 mm in diameter) cyst-like lesion in the liver. Positron emission tomography demonstrated no increased metabolism in the area of the cyst, suggesting a benign character of the lesion. However, after 3 years, CT scans revealed enlargement of the cyst, and local surgical excision was performed. The results of histopathological examination of the resected material were consistent with metastatic leiomyosarcoma. Subsequently, the patient developed lung metastases and died within 2 years. Our case describes a very rare presentation of leiomyosarcoma's metastasis that led to an ill-fated misdiagnosis and dismal disease outcome.

A 'Real-Life' Experience on Automated Digital Image Analysis of FGFR2 Immunohistochemistry in Breast Cancer.

We present here an assessment of a 'real-life' value of automated machine learning algorithm (AI) for examination of immunohistochemistry for fibroblast growth factor receptor-2 (FGFR2) in breast cancer (BC). Expression of FGFR2 in BC (n = 315) measured using a certified 3DHistech CaseViewer/QuantCenter software 2.3.0. was compared to the manual pathologic assessment in digital slides (PA). Results revealed: (i) substantial interrater agreement between AI and PA for dichotomized evaluation (Cohen's kappa = 0.61); (ii) strong correlation between AI and PA H-scores (Spearman r = 0.85, p < 0.001); (iii) a small constant error and a significant proportional error (Passing-Bablok regression y = 0.51 × X + 29.9, p < 0.001); (iv) discrepancies in H-score in cases of extreme (strongest/weakest) or heterogeneous FGFR2 expression and poor tissue quality. The time of AI was significantly longer (568 h) than that of the pathologist (32 h). This study shows that the described commercial machine learning algorithm can reliably execute a routine pathologic assessment, however, in some instances, human expertise is essential.

Upregulation of HIF1-α via an NF-κB/COX2 pathway confers proliferative dominance of HER2-negative ductal carcinoma in situ cells in response to inflammatory stimuli.

There are data to suggest that some ductal carcinoma in situ (DCIS) may evolve through an evolutionary bottleneck, where minor clones susceptible to the imposed selective pressure drive disease progression. Here, we tested the hypothesis that an impact of the inflammatory environment on DCIS evolution is HER2-dependent, conferring proliferative dominance of HER2-negative cells. In tissue samples, density of tumour-infiltrating immune cells (TIICs) was associated only with high tumour nuclear grade, but in 9% of predominantly HER2-negative cases, the presence of tumoral foci ('hot-spots') of basal-like cells with HIF1-α activity adjacent to the areas of dense stromal infiltration was noted. Results of in vitro analyses further demonstrated that IL-1ß and TNF-α as well as macrophage-conditioned medium triggered phosphorylation of NF-κB and subsequent upregulation of COX2 and HIF1-α, exclusively in HER2-negative cells. Treatment with both IL-1ß and TNF-α resulted in growth stimulation and inhibition of HER2-negative and HER2-positive cells, respectively. Moreover, ectopic overexpression of HIF1-α rescued HER2-positive cells from the negative effect of IL-1ß and TNF-α on cell growth. Our data provide novel insight into the molecular basis of HER2-dependent proliferation of DCIS cells and indicate the NF-κB/COX2 → HIF1-α signalling axis as a dominant mechanism of DCIS evolution induced by inflammatory microenvironment. Presented findings also highlight the clinical significance of heterogeneity of DCIS tumours and suggest that HIF1-α might be considered as a predictive marker of disease progression.

Hormonal Receptor Status Determines Prognostic Significance of FGFR2 in Invasive Breast Carcinoma.

Interaction between fibroblast growth factor receptor 2 (FGFR2) and estrogen/progesterone receptors (ER/PR) affects resistance to anti-ER therapies, however the prognostic value of FGFR2 in breast cancer (BCa) remains largely unexplored. We have recently showed in vitro that FGFR2-mediated signaling alters PR activity and response to anti-ER treatment. Herein, prognostic significance of FGFR2 in BCa was evaluated in relation to both ER/PR protein status and a molecular signature designed to reflect PR transcriptional activity. FGFR2 was examined in 353 BCa cases using immunohistochemistry and Nanostring-based RNA quantification. FGFR2 expression was higher in ER+PR+ and ER+PR- compared to ER-PR- cases (p < 0.001). Low FGFR2 was associated with higher grade (p < 0.001), higher Ki67 proliferation index (p < 0.001), and worse overall and disease-free survival (HR = 2.34 (95% CI: 1.26-4.34), p = 0.007 and HR = 2.22 (95% CI: 1.25-3.93), p = 0.006, respectively). The poor prognostic value of low FGFR2 was apparent in ER+PR+, but not in ER+PR- patients, and it did not depend on the expression level of PR-dependent genes. Despite the functional link between FGFR2 and ER/PR revealed by preclinical studies, the data showed a link between FGFR2 expression and poor prognosis in BCa patients.

The diagnostic challenge in pulmonary tumour embolism in cancer: a case report and literature review.

Pulmonary tumour embolism is a rare condition without specific symptoms or pathognomonic features. Pulmonary tumour embolism can occur as the first manifestation of cancer, but because of diagnostic difficulties, it is often wrongly recognised as a more common cardiopulmonary disease. We present a case of a 46-year-old Caucasian male with no prior malignancy diagnosis, admitted because of progressing dyspnoea and cough. Based on radiological and clinical presentations, sarcoidosis, silicosis and lymphangitic carcinomatosis were considered in the differential diagnosis. Histopathological analysis of lung biopsy revealed that multiple emboli of atypical epithelial cells found in the pulmonary vessels were of gastrointestinal origin. Further pathological examination of the gastric biopsy led to the final diagnosis of the signet-ring cells gastric adenocarcinoma. The patient was referred for chemotherapy. After a short-term partial remission, he died within two months after the final diagnosis. The presented case illustrates challenges posed by the diagnostic process of pulmonary tumour embolism.

Adenoid cystic carcinoma of the breast - an uncommon malignancy with unpredictable clinical behaviour. A case series of three patients.

Adenoid cystic carcinoma (AdCC) is a common tumour of the minor salivary gland, rarely seen in other anatomical locations. In particular, AdCC of the breast accounts for < 0.1% of patients diagnosed with breast cancer. Here we report our institutional experience with three cases of breast AdCC diagnosed between 2009 and 2017. Mean age of women included in the report was 53 (range from 41 to 62). One case was of no special subtype, two were solid variants and one presented with a component of invasive ductal carcinoma. At diagnosis in all cases neither lymph node involvement nor distal metastases were detected. All patients underwent surgical resection of the tumour - mastectomy or lumpectomy, followed by either adjuvant radiotherapy and chemotherapy (one case), chemotherapy without radiotherapy (one case) or no treatment (one case). Two patients were reported to develop metastatic disease. No deaths were recorded. In contrast to other anatomical locations AdCC of the breast is regarded as a rare tumour with low malignant potential. However, as shown in our case series, it can present as an aggressive disease with distal metastases, which calls for deep awareness among both pathologists and clinicians involved in the process of diagnosis and therapy.

Tetraspanin CD151 impairs heterodimerization of ErbB2/ErbB3 in breast cancer cells.

CD151/Tspan24 (SFS-1, PETA3) is one of the best characterized members of the tetraspanin family, whose involvement in breast cancer (BCa) progression was demonstrated both in vitro and in vivo. We have recently reported that in ErbB2-overexpressing BCa cells grown in 3D laminin-rich extracellular matrix, CD151 regulated basal phosphorylation and homodimerization of ErbB2 and sensitized the cells to Herceptin (trastuzumab). Following from these data, we have here analyzed an involvement of CD151 in regulation of ErbB2/ErbB3 heterodimerization and its impact on cell response to Herceptin. CD151 was found to: (1) impair ErbB2/ErbB3 heterodimerization, (2) inhibit heregulin-dependent cell growth in 3D and signaling, and (3) counteract the protective effect of heregulin on Herceptin-mediated growth inhibition. Analysis of tissue samples demonstrated for the first time clinical significance of CD151 in patients with ErbB2-overexpressing BCa undergone trastuzumab-based therapy. Consistent with in vitro results, CD151 impact on disease outcome was ErbB3-dependent. In patients with ErbB3-negative tumors, CD151 significantly improved both overall survival (OS) (hazard ratio [HR] = 0.19, P = 0.034) and progression-free survival (PFS) (HR = 0.36, P = 0.043), while in ErbB3-positive cases it had no significant effect on patient survival (OS: HR = 3.33, P = 0.283; PFS: HR = 2.40, P = 0.208). These results support previous findings and show that CD151 acts as an important component of ErbB2 signaling axis in BCa cells, affecting their sensitivity to ErbB2-targeting therapy.

RSK1 promotes murine breast cancer growth and metastasis.

INTRODUCTION: Triple-negative breast cancer (TNBC), representing over 15% of all breast cancers, has a poorer prognosis than other subtypes. There is no effective targeted treatment available for the TNBC sufferers. Ribosomal S6 kinases (RSKs) have been previously proposed as drug targets for TNBC based on observations that 85% of these tumors express activated RSKs. MATERIALS AND METHODS: Herein we examined an involvement of RSK1 (p90 ribosomal S6 kinase 1) in a regulation of TNBC growth and metastatic spread in an animal model, which closely imitates human disease. Mice were inoculated into mammary fat pad with 4T1 cells or their RSK1-depleted variant. We examined tumor growth and formation of pulmonary metastasis. Boyden chamber, wound healing and soft agarose assays were performed to evaluate cells invasion, migration and anchorage-independent growth. RESULTS: We found that RSK1 promoted tumor growth and metastasis in vivo. After 35 days all animals inoculated with control cells developed tumors while in the group injected with RSK1-negative cells, there were 75% tumor-bearing mice. Average tumor mass was estimated as 1.16 g and 0.37 g for RSK1-positive vs. -negative samples, respectively (p < 0.0001). Quantification of the macroscopic pulmonary metastases indicated that mice with RSK1-negative tumors developed approximately 85% less metastatic foci on the lung surface (p < 0.001). This has been supported by in vitro data presenting that RSK1 promoted anchorage-independent cell growth and migration. Moreover, RSK1 knock-down corresponded with decreased expression of cell cycle regulating proteins, i.e. cyclin D3, CDK6 and CDK4. CONCLUSIONS: We provide evidence that RSK1 supports tumor growth and metastatic spread in vivo as well as in vitro migration and survival in non-adherent conditions. Further studies of RSK1 involvement in TNBC progression may substantiate our findings, laying the foundations for development of anti-RSK1-based therapeutic strategies in the management of patients with TNBC.

Progesterone impairs Herceptin effect on breast cancer cells.

Breast cancer (BCa) is the most common cancer affecting women worldwide. Overexpression of human epidermal growth factor receptor 2 (HER2) occurs in ~20-25% of invasive ductal breast carcinomas and is associated with the more aggressive phenotype. Herceptin, a humanized antibody against HER2, is a standard therapy in HER2-overexpressing cases. Approximately one-third of patients relapse despite treatment. Therefore numerous studies have investigated the molecular mechanisms associated with Herceptin resistance. An interaction between HER2 signalling and steroid hormone receptor signalling pathways has been previously investigated, but the effect of this relationship on Herceptin resistance has never been studied. The present study analysed an impact of the steroid hormone, progesterone (PG), on Herceptin-dependent cell growth inhibition. Results indicated that Herceptin-inhibited proliferation of breast cancer cell lines overexpressing HER2 (BT474 and MCF/HER2) in 3D culture is abolished by PG. Furthermore, results demonstrated that PG led to the activation of HER2/HER3-mediated signalling. Moreover, PG treatment induced a shift of Herceptin-dependent cell cycle arrest in G1 phase towards S and G2 phases with concomitant upregulation of cyclin-dependent kinase 2 (CDK2) and downregulation of CDK inhibitor p27Kip1. These results demonstrate for the first time PG involvement in the failure of Herceptin treatment in vitro. The present observations suggest that cross-talk between PG- and HRG/HER2-initiated signalling pathways may lead to the acquisition of resistance to Herceptin in patients with BCa.

FGFR2-Driven Signaling Counteracts Tamoxifen Effect on ERα-Positive Breast Cancer Cells.

Signaling mediated by growth factors receptors has long been suggested as one of the key factors responsible for failure of endocrine treatment in breast cancer (BCa). Herein we present that in the presence of tamoxifen, FGFs (Fibroblast Growth Factors) promote BCa cell growth with the strongest effect being produced by FGF7. FGFR2 was identified as a mediator of FGF7 action and the FGFR2-induced signaling was found to underlie cancer-associated fibroblasts-dependent resistance to tamoxifen. FGF7/FGFR2-triggered pathway was shown to induce ER phosphorylation, ubiquitination and subsequent ER proteasomal degradation which counteracted tamoxifen-promoted ER stabilization. We also identified activation of PI3K/AKT signaling targeting ER-Ser167 and regulation of Bcl-2 expression as a mediator of FGFR2-promoted resistance to tamoxifen. Analysis of tissue samples from patients with invasive ductal carcinoma revealed an inversed correlation between expression of FGFR2 and ER, thus supporting our in vitro data. These results unveil the complexity of ER regulation by FGFR2-mediated signaling likely to be associated with BCa resistance to endocrine therapy.

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation.

The tetraspanins are a superfamily of four-transmembrane proteins, which regulate the trafficking, lateral diffusion and clustering of the transmembrane proteins with which they interact. We have previously shown that tetraspanin Tspan9 is expressed on platelets. Here we have characterised gene-trap mice lacking Tspan9. The mice were viable with normal platelet numbers and size. Tspan9-deficient platelets were specifically defective in aggregation and secretion induced by the platelet collagen receptor GPVI, despite normal surface GPVI expression levels. A GPVI activation defect was suggested by partially impaired GPVI-induced protein tyrosine phosphorylation. In mechanistic experiments, Tspan9 and GPVI co-immunoprecipitated and co-localised, but super-resolution imaging revealed no defects in collagen-induced GPVI clustering on Tspan9-deficient platelets. However, single particle tracking using total internal reflection fluorescence microscopy showed that GPVI lateral diffusion was reduced by approximately 50% in the absence of Tspan9. Therefore, Tspan9 plays a fine-tuning role in platelet activation by regulating GPVI membrane dynamics.

Fibroblast growth factor signalling induces loss of progesterone receptor in breast cancer cells.

We have recently demonstrated that, fibroblast growth factor 2 (FGFR2), signalling via ribosomal S6 kinase 2 (RSK2), promotes progression of breast cancer (BCa). Loss of progesterone receptor (PR), whose activity in BCa cells can be stimulated by growth factor receptors (GFRs), is associated with poor patient outcome. Here we showed that FGF7/FGFR2 triggered phosphorylation of PR at Ser294, PR ubiquitination and subsequent receptor`s degradation via the 26S proteasome pathway in BCa cells. We further demonstrated that RSK2 mediated FGF7/FGFR2-induced PR downregulation. In addition, a strong synergistic effect of FGF7 and progesterone (Pg), reflected in the enhanced anchorage-independent growth and cell migration, was observed. Analysis of clinical material demonstrated that expression of PR inversely correlated with activated RSK (RSK-P) (p = 0.016). Patients with RSK-P(+)/PR(-) tumours had 3.629-fold higher risk of recurrence (p = 0.002), when compared with the rest of the cohort. Moreover, RSK-P(+)/PR(-) phenotype was shown as an independent prognostic factor (p = 0.006). These results indicate that the FGF7/FGFR2-RSK2 axis promotes PR turnover and activity, which may sensitize BCa cells to stromal stimuli and contribute to the progression toward steroid hormone negative BCa.

Interactions between FGFR2 and RSK2-implications for breast cancer prognosis.

We have previously demonstrated that fibroblast growth factor receptor 2 (FGFR2) activates ribosomal s6 kinase 2 (RSK2) in mammary epithelial cells and that this pathway promotes in vitro cell growth and migration. Potential clinical significance of FGFR2 and RSK2 association has never been investigated. Herein, we have undertaken an evaluation of a possible relationship between FGFR2/RSK2 interdependence and disease outcome in breast cancer (BCa) patients. The clinical analysis was complemented by an in vitro investigation of an involvement of RSK2 in the regulation of FGFR2 function. Primary tumour samples from 152 stage I-III BCa patients were examined for FGFR2 and RSK2 gene and protein expression. FGFR2 showed a positive correlation with RSK2 at both protein (p = 0.003) and messenger RNA (mRNA) (p = 0.001) levels. Lack of both FGFR2 and activated RSK (RSK-P) significantly correlated with better disease-free survival (DFS) (p = 0.01). Patients with tumours displaying immunoreactivity for either or both FGFR2 and RSK-P had 4.89-fold higher risk of recurrence when compared to the FGFR2/RSK-P-negative subgroup. FGFR2-RSK2 interactions were verified by co-immunoprecipitation and internalization assays in HB2 mammary epithelial cell line (characterized by high endogenous FGFR2 and RSK2 expression). In vitro analyses revealed that FGFR2 and RSK2 formed an indirect complex and that activated RSK exerted a significant impact on fibroblast growth factor 2 (FGF2)-triggered internalization of FGFR2. Our results suggest that the FGFR2-RSK2 signalling pathway is involved in pathophysiology of BCa and evaluation of FGFR2/RSK-P expression may be useful in disease prognostication.

[Aspects of progesterone receptor (PR) activity regulation - impact on breast cancer progression]. / Aspekty regulacji aktywnosci receptora progesteronu (PR) - znaczenie w progresji raka gruczolu piersiowego.

Progesterone receptor (PR) and its specific ligand play a key role in development and physiology of mammary gland. The role of PR in initiation and progression of breast carcinoma (BCa) is unquestionable, although molecular mechanism of PR action is complex and not fully understood. It is known that increased risk of breast cancer is associated with progestin-based (synthetic ligands of progesterone) hormonal contraception or hormone replacement therapies. It is estimated that ER/PR-positive tumours represent approximately 50-70% of all BCa cases, and the loss of PR is associated with resistance to hormonal therapy and increased tumour invasiveness. In classical, genomic signalling pathway cytoplasmic PR, following ligand binding, translocates to the nucleus and regulates expression of genes with the PRE sequence. PR is also involved in a large number of alternative, non-genomic signalling cascades, e.g. PR is able to activate MAPK and PI3K/AKT pathways, which leads to regulation of gene expression. The cross-talk between PR and Growth Factors Receptors (GFR) results in progesterone-independent activation of PR as well as PR-regulated GFR expression and activation. Growth factors signalling promotes formation of a pool of hypersensitive PR responsive to even very low ligand concentration. Transcriptional activity of PR as well as its dynamic impact on processes such as cell migration and adhesion are crucial for BCa progression. Further studies of multifaceted mechanisms of PR action may contribute to new PR-targeting therapeutic strategies for breast cancer patients.

Expression of CD151/Tspan24 and integrin alpha 3 complex in aid of prognostication of HER2-negative high-grade ductal carcinoma in situ.

The pro-tumorigenic and pro-metastatic functions of the tetraspanin protein CD151 (Tspan24) are thought to be dependent on its ability to form complexes with laminin-binding integrin receptors (i.e. alpha6beta1, alpha3beta1, alpha6beta4). We have previously reported that in invasive ductal carcinoma (IDC), CD151/alpha3beta1 complex was of prognostic value in patients with HER2-negative tumors. Extrapolating these findings to the pre-invasive setting, we aimed to make an assessment of a potential relationship between expression of the CD151/alpha3beta1 complex in DCIS and Van Nuys prognostic index (VNPI) in high-grade ductal carcinoma in situ (DCIS) in relation to the HER2 status. Protein distributions were analyzed in 49 samples of pure DCIS using immunohistochemistry. For each case immunoreactivity was assessed in at least 5 ducts (325 ducts in total) and an average score was taken for statistical analyses. When analyzed in the whole cohort, there was no statistical association between the VNPI and any of the proteins scored either separately or in combination. When stratified according to the HER2 status, in the HER2-negative subgroup, CD151 assessed in combination with alpha3beta1 was significantly correlated with VNPI (P = 0.044), while neither protein analyzed individually showed any significant link with the prognostic index. Expression of the CD151/alpha3beta1 complex in HER2-negative DCIS might reflect tumor behavior relevant to the patient outcome and thus might aid prognostication of the disease.