Expression of cancer-associated fibroblast-related proteins in adipose stroma of breast cancer

Exploring the value of FAP-targeted PET/CT in differentiating breast cancer molecular subtypes: a preliminary study

PURPOSE

This prospective study aims to evaluate the value of [18F]AlF-NOTA-fibroblast activation protein inhibitor (FAPI)-04 positron emission tomography-computed tomography (PET/CT) in predicting molecular subtypes of breast cancer.

METHODS

The study consecutively recruited patients suspected of having breast cancer from a single center who were prospectively enrolled from July 2023 to May 2024 and underwent [18F]AlF-NOTA-FAPI-04 PET/CT. This study compared the differences in tracer uptake among breast cancers with different adverse prognostic factors and molecular subtypes. The classification performance for each molecular subtype of breast cancer was assessed using a receiver operating characteristic (ROC) curve.

RESULTS

Fifty-three participants (mean age, 51 ± 11 years; 52 females) were evaluated. Breast cancer lesions with adverse prognostic factors showed higher tracer uptake. The five different molecular subtypes exhibited varying levels of uptake. The luminal A and luminal B (HER2-negative) subtypes had relatively low uptake, while the luminal B (HER2-positive), HER2-positive, and triple-negative subtypes had relatively high uptake. ROC analysis identified the max standardized uptake value (SUVmax) as a significant classifier (AUC = 0.912, P = 0.0005) for the luminal A subtype, with 100% sensitivity and 83% specificity. For predicting the luminal B (HER2-negative) subtype, SUVmax had an AUC of 0.770 (P = 0.0015). SUVmax, with an AUC of 0.781 (P = 0.003), was used to identify the triple-negative subtype tumors, resulting in a sensitivity of 100% and specificity of 51%. Lastly, the ROC curve showed the cut-off 15.40 (AUC = 0.921, P < 0.0001) could classify luminal A & luminal B (HER2-negative), and luminal B (HER2-positive) & HER2-positive & triple-negative, yielding a sensitivity of 94% and specificity of 79%.

CONCLUSION

The uptake of [18F]AlF-NOTA-FAPI-04 is significantly correlated with the molecular subtypes of breast cancer, and [18F]AlF-NOTA-FAPI-04 PET/CT is a potential tool for noninvasive identification of luminal A subtypes and guidance of FAP-targeted therapies.

Mitochondrial Ca2+ signaling is a hallmark of specific adipose tissue-cancer crosstalk

Obesity is associated with increased risk and worse prognosis of many tumours including those of the breast and of the esophagus. Adipokines released from the peritumoural adipose tissue promote the metastatic potential of cancer cells, suggesting the existence of a crosstalk between the adipose tissue and the surrounding tumour. Mitochondrial Ca2+ signaling contributes to the progression of carcinoma of different origins. However, whether adipocyte-derived factors modulate mitochondrial Ca2+ signaling in tumours is unknown. Here, we show that conditioned media derived from adipose tissue cultures (ADCM) enriched in precursor cells impinge on mitochondrial Ca2+ homeostasis of target cells. Moreover, in modulating mitochondrial Ca2+ responses, a univocal crosstalk exists between visceral adipose tissue-derived preadipocytes and esophageal cancer cells, and between subcutaneous adipose tissue-derived preadipocytes and triple-negative breast cancer cells. An unbiased metabolomic analysis of ADCM identified creatine and creatinine for their ability to modulate mitochondrial Ca2+ uptake, migration and proliferation of esophageal and breast tumour cells, respectively.

The relationship between cancer associated fibroblasts biomarkers and prognosis of breast cancer: a systematic review and meta-analysis

Background

To elucidate the relationship between cancer-associated fibroblast (CAFs) biomarkers and the prognosis of breast cancer patients for individualized CAFs-targeting treatment.

Methodology

PubMed, Web of Science, Cochrane, and Embase databases were searched for CAFs-related studies of breast cancer patients from their inception to September, 2023. Meta-analysis was performed using R 4.2.2 software. Sensitivity analyses were performed to explore the sources of heterogeneity. Funnel plot and Egger's test were used to assess the publication bias.

Results

Twenty-seven studies including 6,830 patients were selected. Univariate analysis showed that high expression of platelet-derived growth factor receptor-β (PDGFR-β) (P = 0.0055), tissue inhibitor of metalloproteinase-2 (TIMP-2) (P < 0.0001), matrix metalloproteinase (MMP) 9 (P < 0.0001), MMP 11 (P < 0.0001) and MMP 13 (P = 0.0009) in CAFs were correlated with reduced recurrence-free survival (RFS)/disease-free survival (DFS)/metastasis-free survival (MFS)/event-free survival (EFS) respectively. Multivariate analysis showed that high expression of α-smooth muscle actin (α-SMA) (P = 0.0002), podoplanin (PDPN) (P = 0.0008), and PDGFR-β (P = 0.0470) in CAFs was associated with reduced RFS/DFS/MFS/EFS respectively. Furthermore, PDPN and PDGFR-β expression in CAFs of poorly differentiated breast cancer patients were higher than that of patients with relatively better differentiated breast cancer. In addition, there is a positive correlation between the expression of PDPN and human epidermal growth factor receptor-2 (HER-2).

Conclusions

The high expression of α-SMA, PDPN, PDGFR-β in CAFs leads to worse clinical outcomes in breast cancer, indicating their roles as prognostic biomarkers and potential therapeutic targets.

The Keratinocyte in the Picture Cutaneous Melanoma Microenvironment

Melanoma progression is a multistep evolution from a common melanocytic nevus through a radial superficial growth phase, the invasive vertical growth phase finally leading to metastatic dissemination into distant organs. Melanoma aggressiveness largely depends on the propensity to metastasize, which means the capacity to escape from the physiological microenvironment since tissue damage due to primary melanoma lesions is generally modest. Physiologically, epidermal melanocytes are attached to the basement membrane, and their adhesion/migration is under the control of surrounding keratinocytes. Thus, the epidermal compartment represents the first microenvironment responsible for melanoma spread. This complex process involves cell-cell contact and a broad range of secreted bioactive molecules. Invasion, or at the beginning of the microinvasion, implies the breakdown of the dermo-epidermal basement membrane followed by the migration of neoplastic melanocytic cells in the superficial papillary dermis. Correspondingly, several experimental evidences documented the structural and functional rearrangement of the entire tissue surrounding neoplasm that in some way reflects the atypia of tumor cells. Lastly, the microenvironment must support the proliferation and survival of melanocytes outside the normal epidermal-melanin units. This task presumably is mostly delegated to fibroblasts and ultimately to the self-autonomous capacity of melanoma cells. This review will discuss remodeling that occurs in the epidermis during melanoma formation as well as skin changes that occur independently of melanocytic hyperproliferation having possible pro-tumoral features.

The importance of cancer-associated fibroblasts in targeted therapies and drug resistance in breast cancer

Cancer-associated fibroblasts (CAFs) play a substantial role in the tumor microenvironment, exhibiting a strong association with the advancement of various types of cancer, including breast, pancreatic, and prostate cancer. CAFs represent the most abundant mesenchymal cell population in breast cancer. Through diverse mechanisms, including the release of cytokines and exosomes, CAFs contribute to the progression of breast cancer by influencing tumor energy metabolism, promoting angiogenesis, impairing immune cell function, and remodeling the extracellular matrix. Moreover, CAFs considerably impact the response to treatment in breast cancer. Consequently, the development of interventions targeting CAFs has emerged as a promising therapeutic approach in the management of breast cancer. This article provides an analysis of the role of CAFs in breast cancer, specifically in relation to diagnosis, treatment, drug resistance, and prognosis. The paper succinctly outlines the diverse mechanisms through which CAFs contribute to the malignant behavior of breast cancer cells, including proliferation, invasion, metastasis, and drug resistance. Furthermore, the article emphasizes the potential of CAFs as valuable tools for early diagnosis, targeted therapy, treatment resistance, and prognosis assessment in breast cancer, thereby offering novel approaches for targeted therapy and overcoming treatment resistance in this disease.

Fibroblast activation protein as a potential theranostic target in brain metastases of diverse solid tumours

Brain metastases are a very common and serious complication of oncological diseases. Despite the vast progress in multimodality treatment, brain metastases significantly decrease the quality of life and prognosis of patients. Therefore, identifying new targets in the microenvironment of brain metastases is desirable. Fibroblast activation protein (FAP) is a transmembrane serine protease typically expressed in tumour-associated stromal cells. Due to its characteristic presence in the tumour microenvironment, FAP represents an attractive theranostic target in oncology. However, there is little information on FAP expression in brain metastases. In this study, we quantified FAP expression in samples of brain metastases of various primary origin and characterised FAP-expressing cells. We have shown that FAP expression is significantly higher in brain metastases in comparison to non-tumorous brain tissues, both at the protein and enzymatic activity levels. FAP immunopositivity was localised in regions rich in collagen and containing blood vessels. We have further shown that FAP is predominantly confined to stromal cells expressing markers typical of cancer-associated fibroblasts (CAFs). We have also observed FAP immunopositivity on tumour cells in a portion of brain metastases, mainly originating from melanoma, lung, breast, and renal cancer, and sarcoma. There were no significant differences in the quantity of FAP protein, enzymatic activity, and FAP+ stromal cells among brain metastasis samples of various origins, suggesting that there is no association of FAP expression and/or presence of FAP+ stromal cells with the histological type of brain metastases. In summary, we are the first to establish the expression of FAP and characterise FAP-expressing cells in the microenvironment of brain metastases. The frequent upregulation of FAP and its presence on both stromal and tumour cells support the use of FAP as a promising theranostic target in brain metastases.

Reassessing Breast Cancer-Associated Fibroblasts (CAFs) Interactions with Other Stromal Components and Clinico-Pathologic Parameters by Using Immunohistochemistry and Digital Image Analysis (DIA)

BACKGROUND

Breast cancer (BC) stroma has CD34- and αSMA-positive cancer-associated fibroblasts (CAFs) differently distributed. During malignant transformation, CD34-positive fibroblasts decrease while αSMA-positive CAFs increase. The prevalence of αSMA-positive CAFs in BC stroma makes microscopic examination difficult without digital image analysis processing (DIA). DIA was used to compare CD34- and αSMA-positive CAFs among breast cancer molecular subgroups. DIA-derived data were linked to age, survival, tumor stroma vessels, tertiary lymphoid structures (TLS), invasion, and recurrence.

METHODS

Double immunostaining for CD34 and αSMA showed different CAF distribution patterns in normal and BC tissues. Single CD34 immunohistochemistry on supplemental slides quantified tumor stroma CD34_CAFs. Digital image analysis (DIA) data on CAF density, intensity, stromal score, and H-score were correlated with clinico-pathologic factors.

RESULTS

CD34/αSMA CAF proportion was significantly related to age in Luminal A (LA), Luminal B (LB), and HER2 subtypes. CD34_CAF influence on survival, invasion, and recurrence of LA, LB-HER2, and TNBC subtypes was found to be significant. The CD34/αSMA-expressing CAFs exhibited a heterogeneous impact on stromal vasculature and TLS.

CONCLUSION

BC stromal CD34_CAFs/αSMA_CAFs have an impact on survival, invasion, and recurrence differently between BC molecular subtypes. The tumor stroma DIA assessment may have predictive potential to prognosis and long-term follow-up of patients with breast cancer.

68Ga-FAPI Versus 18F-FDG PET/CT in Evaluating Newly Diagnosed Breast Cancer Patients: A Head-to-Head Comparative Study

PURPOSE

This study aimed to compare the performance of 68Ga-FAPI and 18F-FDG PET/CT in the evaluation of patients with newly diagnosed breast cancer.

METHODS

Thirty-four women with newly diagnosed breast cancer who underwent both 68Ga-FAPI and 18F-FDG PET/CT within 1 week were prospectively included in the study. The imaging characteristics of primary lesions, diagnostic efficiency of lymph node metastasis (LNM), and accuracy of N stage evaluation between 2 PET/CTs were compared.

RESULTS

68Ga-FAPI showed higher SUVmax (11.06 ± 5.48 vs 8.33 ± 6.07, P = 0.02) and tumor-to-background ratio (15.32 ± 10.33 vs 8.25 ± 5.51, P < 0.001) than 18F-FDG in primary tumors. 68Ga-FAPI SUVmax was positively correlated with the pathological grade of the primary lesions and the final stage of the patients (P < 0.001). The specificity and accuracy of 68Ga-FAPI was higher than that of 18F-FDG in the diagnosis of LNMs on patient-based and lesion-based analysis (P < 0.001). The accuracy for the evaluation of N stage and N0 axillar status was 91.2% (31/34) and 85.7% (12/14) for 68Ga-FAPI, and 73.5% (25/34) and 42.9% (6/14) for 18F-FDG, respectively.

CONCLUSIONS

The 68Ga-FAPI SUVmax was positively correlated with the pathological grade of the primary lesions and the final stage of the patients. 68Ga-FAPI PET/CT has higher accuracy than 18F-FDG in the evaluation of N stage, especially N0 axillar status, which is helpful to improve the treatment strategy for breast cancer patients.

The Superiority of Fibroblast Activation Protein Inhibitor (FAPI) PET/CT Versus FDG PET/CT in the Diagnosis of Various Malignancies

Cancer represents a major cause of death worldwide and is characterized by the uncontrolled proliferation of abnormal cells that escape immune regulation. It is now understood that cancer-associated fibroblasts (CAFs), which express specific fibroblast activation protein (FAP), are critical participants in tumor development and metastasis. Researchers have developed various FAP-targeted probes for imaging of different tumors from antibodies to boronic acid-based inhibitor molecules and determined that quinoline-based FAP inhibitors (FAPIs) are the most appropriate candidate as the radiopharmaceutical for FAPI PET/CT imaging. When applied clinically, FAPI PET/CT yielded satisfactory results. Over the past few years, the utility and effectiveness of tumor detection and staging of FAPI PET/CT have been compared with FDG PET/CT in various aspects, including standardized uptake values (SUVs), rate of absorbance and clearance. This review summarizes the development and clinical application of FAPI PET/CT, emphasizing the diagnosis and management of various tumor types and the future prospects of FAPI imaging.

The complex nature of heterogeneity and its roles in breast cancer biology and therapeutic responsiveness

Heterogeneity is a complex feature of cells and tissues with many interacting components. Depending on the nature of the research context, interacting features of cellular, drug response, genetic, molecular, spatial, temporal, and vascular heterogeneity may be present. We describe the various forms of heterogeneity with examples of their interactions and how they play a role in affecting cellular phenotype and drug responses in breast cancer. While cellular heterogeneity may be the most widely described and invoked, many forms of heterogeneity are evident within the tumor microenvironment and affect responses to the endocrine and cytotoxic drugs widely used in standard clinical care. Drug response heterogeneity is a critical determinant of clinical response and curative potential and also is multifaceted when encountered. The interactive nature of some forms of heterogeneity is readily apparent. For example, the process of metastasis has the properties of both temporal and spatial heterogeneity within the host, whereas each individual metastatic deposit may exhibit cellular, genetic, molecular, and vascular heterogeneity. This review describes the many forms of heterogeneity, their integrated activities, and offers some insights into how heterogeneity may be understood and studied in the future.

Research progress on the role of fibroblast activation protein in diagnosis and treatment of cancer

Fibroblast activation protein (FAP) is a type II transmembrane protein, which is over-expressed in cancer-associated fibroblasts (CAFs). CAFs are tumor stromal cells that constitute a major component of cancer volume and are reportedly related to tumorigenesis, angiogenesis, metastasis, promotion of drug resistance and induction of tumor immunity. FAP is widely acknowledged as the signature protein of CAFs. At present, FAP inhibitors (FAPI) have achieved ideal results in tumor PET/computed tomography (CT) imaging. Theoretically, FAP-targeted drugs can inhibit tumor progression. Nonetheless, no satisfactory therapeutic effect has been observed so far, which has impeded their implementation in clinical practice. In this review, we describe the characteristics of FAP and its role in the occurrence and development of cancer. We also highlight the potential value of targeting FAP to improve current diagnostic and therapeutic approaches.

Immunotherapeutic Targeting of NG2/CSPG4 in Solid Organ Cancers

Neuro-glia antigen 2/chondroitin sulfate proteoglycan 4 (NG2/CSPG4, also called MCSP, HMW-MAA, MSK16, MCSPG, MEL-CSPG, or gp240) is a large cell-surface antigen and an unusual cell membrane integral glycoprotein frequently expressed on undifferentiated precursor cells in multiple solid organ cancers, including cancers of the liver, pancreas, lungs, and kidneys. It is a valuable molecule involved in cancer cell adhesion, invasion, spreading, angiogenesis, complement inhibition, and signaling. Although the biological significance underlying NG2/CSPG4 proteoglycan involvement in cancer progression needs to be better defined, based on the current evidence, NG2/CSPG4⁺ cells, such as pericytes (PCs, NG2⁺/CD146⁺/PDGFR-β⁺) and cancer stem cells (CSCs), are closely associated with the liver malignancy, hepatocellular carcinoma (HCC), pancreatic malignancy, and pancreatic ductal adenocarcinoma (PDAC) as well as poor prognoses. Importantly, with a unique method, we successfully purified NG2/CSPG4-expressing cells from human HCC and PDAC vasculature tissue blocks (by core needle biopsy). The cells appeared to be spheres that stably expanded in cultures. As such, these cells have the potential to be used as sources of target antigens. Herein, we provide new information on the possibilities of frequently selecting NG2/CSPG4 as a solid organ cancer biomarker or exploiting expressing cells such as CSCs, or the PG/chondroitin sulfate chain of NG2/CSPG4 on the cell membrane as specific antigens for the development of antibody- and vaccine-based immunotherapeutic approaches to treat these cancers.

68Ga-FAPI-PET/CT in patients with various gynecological malignancies

PURPOSE

68Ga-FAPI (fibroblast activation protein inhibitor) is a novel and highly promising radiotracer for PET/CT imaging. The aim of this retrospective analysis is to explore the potential of FAPI-PET/CT in gynecological malignancies. We assessed biodistribution, tumor uptake, and the influence of pre- or postmenopausal status on tracer accumulation in hormone-sensitive organs. Furthermore, a comparison with the current standard oncological tracer 18F-FDG was performed in selected cases.

PATIENTS AND METHODS

A total of 31 patients (median age 59.5) from two centers with several gynecological tumors (breast cancer; ovarian cancer; cervical cancer; endometrial cancer; leiomyosarcoma of the uterus; tubal cancer) underwent 68Ga-FAPI-PET/CT. Out of 31 patients, 10 received an additional 18F-FDG scan within a median time interval of 12.5 days (range 1-76). Tracer uptake was quantified by standardized uptake values (SUV)max and (SUV)mean, and tumor-to-background ratio (TBR) was calculated (SUVmax tumor/ SUVmean organ). Moreover, a second cohort of 167 female patients with different malignancies was analyzed regarding their FAPI uptake in normal hormone-responsive organs: endometrium (n = 128), ovary (n = 64), and breast (n = 147). These patients were categorized by age as premenopausal (<35 years; n = 12), postmenopausal (>65 years; n = 68), and unknown menstrual status (35-65 years; n = 87), followed by an analysis of FAPI uptake of the pre- and postmenopausal group.

RESULTS

In 8 out of 31 patients, the primary tumor was present, and all 31 patients showed lesions suspicious for metastasis (n = 81) demonstrating a high mean SUVmax in both the primary (SUVmax 11.6) and metastatic lesions (SUVmax 9.7). TBR was significantly higher in 68Ga-FAPI compared to 18F-FDG for distant metastases (13.0 vs. 5.7; p = 0.047) and by trend for regional lymph node metastases (31.9 vs 27.3; p = 0.6). Biodistribution of 68Ga-FAPI-PET/CT presented significantly lower uptake or no significant differences in 15 out of 16 organs, compared to 18F-FDG-PET/CT. The highest uptake of all primary lesions was obtained in endometrial carcinomas (mean SUVmax 18.4), followed by cervical carcinomas (mean SUVmax 15.22). In the second cohort, uptake in premenopausal patients differed significantly from postmenopausal patients in endometrium (11.7 vs 3.9; p < 0.0001) and breast (1.8 vs 1.0; p = 0.004), whereas no significant difference concerning ovaries (2.8 vs 1.6; p = 0.141) was observed.

CONCLUSION

Due to high tracer uptake resulting in sharp contrasts in primary and metastatic lesions and higher TBRs than 18F-FDG-PET/CT, 68Ga-FAPI-PET/CT presents a promising imaging method for staging and follow-up of gynecological tumors. The presence or absence of the menstrual cycle seems to correlate with FAPI accumulation in the normal endometrium and breast. This first investigation of FAP ligands in gynecological tumor entities supports clinical application and further research in this field.

Colorectal cancer cell intrinsic fibroblast activation protein alpha binds to Enolase1 and activates NF-κB pathway to promote metastasis

Fibroblast activation protein alpha (FAP) is a marker of cancer-associated fibroblast, which is also expressed in cancer epithelial cells. However, the role of FAP in colorectal cancer (CRC) cells remains to be elucidated. Here we investigate the expression pattern of FAP in CRC tissues and cells to prove that FAP is upregulated in CRC cells. Loss- of and gain-of-function assays identified FAP promotes migration and invasion instead of an effect on cell proliferation. Microarray assays are adopted to identify the different expressed genes after FAP knockdown and gene set enrichment analysis (GSEA) is used to exploit the involved signaling pathway. Our works reveal FAP exerts a function dependent on NF-κB signaling pathway and FAP expression is associated with NF-κB signaling pathway in clinical samples. Our work shows FAP is secreted by CRC cells and soluble FAP could promote metastasis. To investigate the mechanism of FAP influencing the NF-κB signaling pathway, LC/MS is performed to identify the proteins interacting with FAP. We find that FAP binds to ENO1 and activates NF-κB signaling pathway dependent on ENO1. Blocking ENO1 could partially reverse the pro-metastatic effect mediated by FAP. We also provide evidences that both FAP and ENO1 are associated with CRC stages, and high levels of FAP and ENO1 predict a poor survival in CRC patients. In summary, our work could provide a novel mechanism of FAP in CRC cells and a potential strategy for treatment of metastatic CRC.

PDGFR-β+ fibroblasts deteriorate survival in human solid tumors: a meta-analysis

Fibroblasts are a highly heterogeneous population in tumor microenvironment. PDGFR-β⁺ fibroblasts, a subpopulation of activated fibroblasts, have proven to correlate with cancer progression through multiple of mechanisms including inducing angiogenesis and immune evasion. However, the prognostic role of these cells in solid tumors is still not conclusive. Herein, we carried out a meta-analysis including 24 published studies with 6752 patients searched from PubMed, Embase and EBSCO to better comprehend the value of such subpopulation in prognosis prediction for solid tumors. We noted that elevated density of intratumoral PDGFR-β⁺ fibroblasts was remarkably associated with worse overall survival (OS) and disease-free survival (DFS) of patients. In subgroup analyses, the data showed that PDGFR-β⁺ fibroblast infiltration considerably decreased OS in non-small cell lung cancer (NSCLC), breast and pancreatic cancer, and reduced DFS in breast cancer. In addition, increased number of PDGFR-β⁺ fibroblasts appreciably correlated with advanced TNM stage of patients. In conclusion, PDGFR-β⁺ fibroblast infiltration deteriorates survival in human solid tumors especially in NSCLC, breast and pancreatic cancer. Hence, they may offer a practicable prognostic biomarker and a potential therapeutic strategy for these patients.

The Role of Cancer-Associated Fibroblasts in Tumor Progression

In the era of genomic medicine, cancer treatment has become more personalized as novel therapeutic targets and pathways are identified. Research over the past decade has shown the increasing importance of how the tumor microenvironment (TME) and the extracellular matrix (ECM), which is a major structural component of the TME, regulate oncogenic functions including tumor progression, metastasis, angiogenesis, therapy resistance, and immune cell modulation, amongst others. Within the TME, cancer-associated fibroblasts (CAFs) have been identified in several systemic cancers as critical regulators of the malignant cancer phenotype. This review of the literature comprehensively profiles the roles of CAFs implicated in gastrointestinal, endocrine, head and neck, skin, genitourinary, lung, and breast cancers. The ubiquitous presence of CAFs highlights their significance as modulators of cancer progression and has led to the subsequent characterization of potential therapeutic targets, which may help advance the cancer treatment paradigm to determine the next generation of cancer therapy. The aim of this review is to provide a detailed overview of the key roles that CAFs play in the scope of systemic disease, the mechanisms by which they enhance protumoral effects, and the primary CAF-related markers that may offer potential targets for novel therapeutics.

The role of fibroblast activation protein in health and malignancy

Fibroblast activation protein-α (FAP) is a type-II transmembrane serine protease expressed almost exclusively to pathological conditions including fibrosis, arthritis, and cancer. Across most cancer types, elevated FAP is associated with worse clinical outcomes. Despite the clear association between FAP and disease severity, the biological reasons underlying these clinical observations remain unclear. Here we review basic FAP biology and FAP's role in non-oncologic and oncologic disease. We further explore how FAP may worsen clinical outcomes via its effects on extracellular matrix remodeling, intracellular signaling regulation, angiogenesis, epithelial-to-mesenchymal transition, and immunosuppression. Lastly, we discuss the potential to exploit FAP biology to improve clinical outcomes.

Expression of Podoplanin in Mammary Cancers in Female Dogs

BACKGROUND/AIM

Mammary neoplasms are very common tumours in female dogs. Cancer-associated fibroblasts (CAFs) play an important role in the oncogenesis process. One of the useful proteins used in the diagnostics of CAFs cells is podoplanin (PDPN). The aim of our study was to assess the expression of PDPN in mammary cancer in female dogs.

MATERIALS AND METHODS

Our study cohort included 61 cancers and 21 adenomas of the mammary tumour in bitches. Expression of podoplanin, Ki-67 and HER2 was determined using the Immunohistochemical (IHC) method. PDPN expression at the mRNA level was determined using real-time PCR.

RESULTS

Expression of PDPN in CAFs was observed in 22.9% of cases of mammary cancers in bitches, with no PDPN expression in adenomas. A positive correlation was found between the expression of PDPN in CAFs and the grade of histological malignancy and expression of Ki-67.

CONCLUSION

PDPN plays a significant role during the process of carcinogenesis of mammary tumours in female dogs.

Unraveling Adipocytes and Cancer Links: Is There a Role for Senescence?

Senescence is characterized by a permanent cell cycle arrest that is elicited in response to different stresses. In addition, senescent cells undergo multiple other phenotypic alterations, such as autophagy modulation, metabolic reprogramming, and the senescence-associated secretory phenotype (SASP). These senescence-related and inflammatory effects prevail within tumors and are strongly controlled by cancer properties, and inflammatory mediators further maintain and propagate the senescence process to adjacent cells. It is important to consider these detrimental effects that may drive tumorigenesis or cancer relapse. Importantly, cancer-associated adipocytes (CAAs) are one of the primary stromal cells in various tumor microenvironments and favor tumor progression by releasing various factors that can mediate local and systemic effects. However, it remains unclear whether CAAs possess senescent features. In this review, we discuss the complex relationship between senescence and CAAs and highlight important considerations for therapeutics.

Cancer associated fibroblasts as novel promising therapeutic targets in breast cancer

Breast cancer is one of the most important women-related malignancies, which is incurable (particularly in advanced stages) and tumor microenvironment is a number one accused part in the inefficiency of current anti-breast cancer therapeutic strategies. The tumor microenvironment is composed of various cellular and acellular components, which provide an optimum condition for freely expanding cancer cells in various cancer types, particularly breast cancer. Cancer-associated fibroblasts (CAFs) are one of the main cell types in the breast tumor region, which can promote various tumor-promoting processes such as expansion, angiogenesis, metastasis and drug resistance. CAFs directly (by cell-to-cell communication) and indirectly (through secreting soluble factors) can exert their tumorigenic functions. We try to elucidate the immunobiology of CAFs, their origin, function, and heterogeneity in association with their role in various cancer-promoting processes in breast cancer. Based on current knowledge, we believe that the origin of CAFs, their subsets, and their specific expressed biomarkers determine their pro- or anti-tumor functions. Therefore, targeting CAF without considering their specific functions may lead to a deleterious outcome. We propose to find and characterize each subtype of CAFs in association with its specific function in different stages of breast cancer to develop novel promising therapeutic approaches against the right CAF subtype.

Prognostic Significance of CT-Attenuation of Tumor-Adjacent Breast Adipose Tissue in Breast Cancer Patients with Surgical Resection

The purpose of this study was to evaluate the prognostic significance of computed tomography (CT)-attenuation of tumor-adjacent breast adipose tissue for predicting recurrence-free survival (RFS) in patients with breast cancer. We retrospectively enrolled 287 breast cancer patients who underwent pretreatment 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT. From non-contrast-enhanced CT images of PET/CT, CT-attenuation values of tumor-adjacent breast adipose tissue (TAT HU) and contralateral breast adipose tissue (CAT HU) were measured. Difference (HU difference) and percent difference (HU difference %) in CT-attenuation values between TAT HU and CAT HU were calculated. The relationships of these breast adipose tissue parameters with tumor factors and RFS were assessed. TAT HU was significantly higher than CAT HU (p < 0.001). TAT HU, HU difference, and HU difference % showed significant correlations with T stage and estrogen receptor and progesterone receptor status (p < 0.05), whereas CAT HU had no significant relationships with tumor factors (p > 0.05). Patients with high TAT HU, HU difference, and HU difference % had significantly worse RFS than those with low values (p < 0.001). In multivariate analysis, TAT HU and HU difference % were significantly associated with RFS after adjusting for clinico-pathologic factors (p < 0.05). CT-attenuation of tumor-adjacent breast adipose tissue was significantly associated with RFS in patients with breast cancer. The findings seem to support the close contact between breast cancer cells and tumor-adjacent adipocytes observed with imaging studies.

A DNA vaccine expressing an optimized secreted FAPα induces enhanced anti-tumor activity by altering the tumor microenvironment in a murine model of breast cancer

Cancer-associated fibroblasts (CAFs), major components of the tumor microenvironment (TME), promote tumor growth and metastasis and inhibit the anti-tumor immune response. We previously constructed a DNA vaccine expressing human FAPα, which is highly expressed by CAFs, to target these cells in the TME, and observed limited anti-tumor effects in the 4T1 breast cancer model. When the treatment time was delayed until tumor nodes formed, the anti-tumor effect of the vaccine completely disappeared. In this study, to improve the safety and efficacy, we constructed a new FAPα-targeted vaccine containing only the extracellular domain of human FAPα with a tissue plasminogen activator signal sequence for enhanced antigen secretion and immunogenicity. The number of CAFs was more effectively reduced by CD8⁺ T cells induced by the new vaccine. This resulted in decreases in CCL2 and CXCL12 expression, leading to a significant decrease in the ratio of myeloid-derived suppressor cells in the TME. Moreover, when mice were treated after the establishment of tumors, the vaccine could still delay tumor growth. To facilitate the future application of the vaccine in clinical trials, we further optimized the gene codons and reduced the homology between the vaccine and the original sequence, which may be convenient for evaluating the vaccine distribution in the human body. These results indicated that the new FAPα-targeted vaccine expressing an optimized secreted human FAPα induced enhanced anti-tumor activity by reducing the number of FAPα⁺ CAFs and enhancing the recruitment of effector T cells in the 4T1 tumor model mice.

Activated Tumor-infiltrating Fibroblasts Predict Worse Prognosis in Breast Cancer Patients

Purpose: Activated tumor-infiltrating fibroblasts were significantly associated with survival of cancer patients. However, they are heterogeneous population, and the prognostic role of these cells in human breast cancer still remains controversial. Herein, we performed the meta-analysis to better understand the role of these cells in prognosis prediction for breast cancer patients.

Methods: We searched PubMed and EBSCO to identify the studies evaluating the association of intratumoral activated fibroblast density detected by immunohistochemical (IHC) method and overall survival (OS) and/or disease-free survival (DFS) in breast cancer patients, then computed extracted data into hazard ratios (HRs) for OS, DFS and clinicopathological features such as lymph node metastasis, TNM stage with STATA 12.0.

Results: A total of 3680 patients with breast cancer from 15 published studies were incorporated into this meta-analysis. We found that the infiltration of activated fibroblasts significantly decreased overall survival (OS) and disease-free survival (DFS) in patients. In stratified analyses, high density of FSP-1⁺ or podoplanin⁺ fibroblasts was significantly associated with worse OS; while α-SMA⁺ or podoplanin⁺ fibroblast infiltration was associated with worse DFS in breast cancer. In addition, elevated number of activated tumor-infiltrating fibroblasts significantly correlated with lymph node metastasis and poor tumor differentiation of patients.

Conclusion: The infiltration of activated fibroblasts, especially the FSP-1⁺ or podoplanin⁺ fibroblasts leads to worse clinical outcome in breast cancer patients, implicating that it is a valuable prognostic biomarker and targeting it may have a potential for effective treatment.

Pro-tumorigenic roles of fibroblast activation protein in cancer: back to the basics

Fibroblast activation protein (FAP) is a cell-surface serine protease that acts on various hormones and extracellular matrix components. FAP is highly upregulated in a wide variety of cancers, and is often used as a marker for pro-tumorigenic stroma. It has also been proposed as a molecular target of cancer therapies, and, especially in recent years, a great deal of research has gone into design and testing of diverse FAP-targeted treatments. Yet despite this growing field of research, our knowledge of FAP's basic biology and functional roles in various cancers has lagged behind its use as a tumor-stromal marker. In this review, we summarize and analyze recent advances in understanding the functions of FAP in cancer, most notably its prognostic value in various tumor types, cellular effects on various cell types, and potential as a therapeutic target. We highlight outstanding questions in the field, the answers to which could shape preclinical and clinical studies of FAP.

Signals from the Adipose Microenvironment and the Obesity-Cancer Link-A Systematic Review

Obesity and its associated metabolic dysregulation are established risk factors for many cancers. However, the biologic mechanisms underlying this relationship remain incompletely understood. Given the rising rates of both obesity and cancer worldwide, and the challenges for many people to lose excess adipose tissue, a systematic approach to identify potential molecular and metabolic targets is needed to develop effective mechanism-based strategies for the prevention and control of obesity-driven cancer. Epidemiologic, clinical, and preclinical data suggest that within the growth-promoting, proinflammatory microenvironment accompanying obesity, crosstalk between adipose tissue (comprised of adipocytes, macrophages and other cells) and cancer-prone cells may occur via obesity-associated hormones, cytokines, and other mediators that have been linked to increased cancer risk and/or progression. We report here a systematic review on the direct "crosstalk" between adipose tissue and carcinomas in humans. We identified 4,641 articles with n = 20 human clinical studies, which are summarized as: (i) breast (n = 7); (ii) colorectal (n = 4); (iii) esophageal (n = 2); (iv) esophageal/colorectal (n = 1); (v) endometrial (n = 1); (vi) prostate (n = 4); and (vii) ear-nose-throat (ENT) cancer (n = 1). Findings from these clinical studies reinforce preclinical data and suggest organ-dependent crosstalk between adipose tissue and carcinomas via VEGF, IL6, TNFα, and other mechanisms. Moreover, visceral white adipose tissue plays a more central role, as it is more bioenergetically active and is associated with a more procancer secretome than subcutaneous adipose tissue. Efforts to eavesdrop and ultimately interfere with this cancer-enhancing crosstalk may lead to new targets and strategies for decreasing the burden of obesity-related cancers. Cancer Prev Res; 10(9); 494-506. ©2017 AACR.

Expression of Pentose Phosphate Pathway-Related Proteins in Breast Cancer

Purpose

The purpose of this study was to assess the expression of pentose phosphate pathway- (PPP-) related proteins and their significance in clinicopathologic factors of breast cancer.

Methods

Immunohistochemical staining for PPP-related proteins (glucose-6-phosphate dehydrogenase [G6PDH], 6-phosphogluconolactonase [6PGL], 6-phosphogluconate dehydrogenase [6PGDH], and nuclear factor-erythroid 2-related factor 2 [NRF2]) was performed using tissue microarray (TMA) of 348 breast cancers. mRNA levels of these markers in publicly available data from the Cancer Genome Atlas project and Kaplan-Meier plotters were analyzed.

Results

Expression of G6PDH and 6PGL was higher in HER-2 type (p < 0.001 and p = 0.009, resp.) and lower in luminal A type. 6PGDH expression was detected only in TNBC subtype (p < 0.001). G6PDH positivity was associated with ER negativity (p = 0.001), PR negativity (p = 0.001), and HER-2 positivity (p < 0.001), whereas 6PGL positivity was associated with higher T stage (p = 0.004). The 562 expression profile from the TCGA database revealed increased expression of G6PDH and 6PG in the tumor compared with normal adjacent breast tissue. The expression of G6PDH was highest in HER-2 type. HER-2 and basal-like subtypes showed higher expression of 6PGDH than luminal types.

Conclusion

PPP-related proteins are differentially expressed in breast cancer according to molecular subtype, and higher expression of G6PDH and 6PGL was noted in HER-2 subtype.

Epigenomic Deconvolution of Breast Tumors Reveals Metabolic Coupling between Constituent Cell Types

Cancer progression depends on both cell-intrinsic processes and interactions between different cell types. However, large-scale assessment of cell type composition and molecular profiles of individual cell types within tumors remains challenging. To address this, we developed epigenomic deconvolution (EDec), an in silico method that infers cell type composition of complex tissues as well as DNA methylation and gene transcription profiles of constituent cell types. By applying EDec to The Cancer Genome Atlas (TCGA) breast tumors, we detect changes in immune cell infiltration related to patient prognosis, and a striking change in stromal fibroblast-to-adipocyte ratio across breast cancer subtypes. Furthermore, we show that a less adipose stroma tends to display lower levels of mitochondrial activity and to be associated with cancerous cells with higher levels of oxidative metabolism. These findings highlight the role of stromal composition in the metabolic coupling between distinct cell types within tumors.

Cancer associated fibroblasts (CAFs) are activated in cutaneous basal cell carcinoma and in the peritumoural skin

Background

Cutaneous basal cell carcinoma (BCC) is the commonest cancer worldwide. BCC is locally invasive and the surrounding stromal microenvironment is pivotal for tumourigenesis. Cancer associated fibroblasts (CAFs) in the microenvironment are essential for tumour growth in a variety of neoplasms but their role in BCC is poorly understood.

Methods

Material included facial BCC and control skin from the peritumoural area and from the buttocks. With next-generation sequencing (NGS) we compared mRNA expression between BCC and peritumoural skin. qRT-PCR, immunohistochemical and immunofluorescent staining were performed to validate the NGS results and to investigate CAF-related cyto-and chemokines.

Results

NGS revealed upregulation of 65 genes in BCC coding for extracellular matrix components pointing at CAF-related matrix remodeling. qRT-PCR showed increased mRNA expression of CAF markers FAP-α, PDGFR-β and prolyl-4-hydroxylase in BCC. Peritumoural skin (but not buttock skin) also exhibited high expression of PDGFR-β and prolyl-4-hydroxylase but not FAP-α. We found a similar pattern for the CAF-associated chemokines CCL17, CCL18, CCL22, CCL25, CXCL12 and IL6 with high expression in BCC and peritumoural skin but absence in buttock skin. Immunofluorescence revealed correlation between FAP-α and PDGFR-β and CXCL12 and CCL17.

Conclusion

Matrix remodeling is the most prominent molecular feature of BCC. CAFs are present within BCC stroma and associated with increased expression of chemokines involved in tumour progression and immunosuppression (CXCL12, CCL17). Fibroblasts from chronically sun-exposed skin near tumours show gene expression patterns resembling that of CAFs, indicating that stromal fibroblasts in cancer-free surgical BCC margins exhibit a tumour promoting phenotype.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12885-017-3663-0) contains supplementary material, which is available to authorized users.

Obesity and cancer: the role of adipose tissue and adipo-cytokines-induced chronic inflammation

Adipose tissue in addition to its ability to keep lipids is now recognized as a real organ with both metabolic and endocrine functions. Recent studies demonstrated that in obese animals is established a status of adipocyte hypoxia and in this hypoxic state interaction between adipocytes and stromal vascular cells contribute to tumor development and progression. In several tumors such as breast, colon, liver and prostate, obesity represents a poor predictor of clinical outcomes. Dysfunctional adipose tissue in obesity releases a disturbed profile of adipokines with elevated levels of pro-inflammatory factors and a consequent alteration of key signaling mediators which may be an active local player in establishing the peritumoral environment promoting tumor growth and progression. Therefore, adipose tissue hypoxia might contribute to cancer risk in the obese population. To date the precise mechanisms behind this obesity-cancer link is not yet fully understood. In the light of information provided in this review that aims to identify the key mechanisms underlying the link between obesity and cancer we support that inflammatory state specific of obesity may be important in obesity-cancer link.

Lysyl Oxidase (LOX) Transcriptionally Regulates SNAI2 Expression and TIMP4 Secretion in Human Cancers

PURPOSE

Epithelial-to-mesenchymal transition (EMT) is important in cancer progression and metastasis. We and others have previously reported that lysyl oxidase (LOX) is overexpressed in aggressive cancers, is associated with increased mortality, and regulates EMT. However, the mechanism by which LOX mediates EMT is unknown. In this study, we investigated the effect of LOX on mediators of EMT.

EXPERIMENTAL DESIGN

We used chromatin immunoprecipitation and promoter luciferase assays to determine the target gene of LOX. To determine the effects of SNAI2 in vivo, we used our metastatic anaplastic thyroid cancer (ATC) mouse model. To investigate the effects of LOX and SNAI2 on MMPs and TIMPs, protein arrays were used. Primary tumors from patients with metastatic, breast and colon cancer, and tissue array for thyroid cancer were assessed for SNAI2 and TIMP4 expression by immunohistochemistry.

RESULTS

We found that LOX knockdown decreases SNAI2 expression in cancer cell lines. Furthermore, knockdown of LOX reduced SNAI2 expression in a metastatic mouse model of thyroid cancer. We also demonstrated that LOX binds and transactivates the SNAI2 promoter. We found a direct correlation in thyroid and breast cancer samples between LOX and SNAI2 expression. To understand how LOX/SNAI2 axis mediates these effects, we performed a comprehensive analysis of MMPs/TIMPs. LOX and SNAI2 depletion reduced TIMP4 secretion. Analysis of SNAI2 and TIMP4 expression showed overexpression of both proteins in aggressive thyroid, colon, and breast tumors.

CONCLUSIONS

Our findings provide new evidence that LOX regulates SNAI2 expression and that SNAI2-mediated TIMP4 secretion plays a role in cancer progression. Clin Cancer Res; 22(17); 4491-504. ©2016 AACR.

4-protein signature predicting tamoxifen treatment outcome in recurrent breast cancer

Estrogen receptor (ER) positive tumors represent the majority of breast malignancies, and are effectively treated with hormonal therapies, such as tamoxifen. However, in the recurrent disease resistance to tamoxifen therapy is common and a major cause of death. In recent years, in-depth proteome analyses have enabled identification of clinically useful biomarkers, particularly, when heterogeneity in complex tumor tissue was reduced using laser capture microdissection (LCM). In the current study, we performed high resolution proteomic analysis on two cohorts of ER positive breast tumors derived from patients who either manifested good or poor outcome to tamoxifen treatment upon recurrence. A total of 112 fresh frozen tumors were collected from multiple medical centers and divided into two sets: an in-house training and a multi-center test set. Epithelial tumor cells were enriched with LCM and analyzed by nano-LC Orbitrap mass spectrometry (MS), which yielded >3000 and >4000 quantified proteins in the training and test sets, respectively. Raw data are available via ProteomeXchange with identifiers PXD000484 and PXD000485. Statistical analysis showed differential abundance of 99 proteins, of which a subset of 4 proteins was selected through a multivariate step-down to develop a predictor for tamoxifen treatment outcome. The 4-protein signature significantly predicted poor outcome patients in the test set, independent of predictive histopathological characteristics (hazard ratio [HR] = 2.17; 95% confidence interval [CI] = 1.15 to 4.17; multivariate Cox regression p value = 0.017). Immunohistochemical (IHC) staining of PDCD4, one of the signature proteins, on an independent set of formalin-fixed paraffin-embedded tumor tissues provided and independent technical validation (HR = 0.72; 95% CI = 0.57 to 0.92; multivariate Cox regression p value = 0.009). We hereby report the first validated protein predictor for tamoxifen treatment outcome in recurrent ER-positive breast cancer. IHC further showed that PDCD4 is an independent marker.