Disentangling ERBB Signaling in Breast Cancer Subtypes-A Model-Based Analysis

Simple Summary

Breast cancer subtypes are characterized by the expression and activity of estrogen-, progesterone- and HER2-receptors and differ by the treatment as well as patient prognosis. Tumors of the HER2-subtype overexpress this receptor and are successfully targeted with anti-HER2 therapies. We wanted to know if the HER2-receptor and the downstream signaling network act similarly also in the other subtypes and if this network could potentially be a therapeutic target beyond the HER2-positive subtype. To this end, we quantitatively assessed the wiring of signaling events in the individual subtypes to unravel the characteristics of HER-signaling. Our data along with a model-based analysis suggest that major parts of the intracellular signal transduction network are unchanged between the different breast cancer subtypes and that the clinical differences mostly come from the different levels at which these receptors are present in tumor cells as well as from the particular mutations that are present in individual tumors.

Abstract

Targeted therapies have shown striking success in the treatment of cancer over the last years. However, their specific effects on an individual tumor appear to be varying and difficult to predict. Using an integrative modeling approach that combines mechanistic and regression modeling, we gained insights into the response mechanisms of breast cancer cells due to different ligand–drug combinations. The multi-pathway model, capturing ERBB receptor signaling as well as downstream MAPK and PI3K pathways was calibrated on time-resolved data of the luminal breast cancer cell lines MCF7 and T47D across an array of four ligands and five drugs. The same model was then successfully applied to triple negative and HER2-positive breast cancer cell lines, requiring adjustments mostly for the respective receptor compositions within these cell lines. The additional relevance of cell-line-specific mutations in the MAPK and PI3K pathway components was identified via L₁ regularization, where the impact of these mutations on pathway activation was uncovered. Finally, we predicted and experimentally validated the proliferation response of cells to drug co-treatments. We developed a unified mathematical model that can describe the ERBB receptor and downstream signaling in response to therapeutic drugs targeting this clinically relevant signaling network in cell line that represent three major subtypes of breast cancer. Our data and model suggest that alterations in this network could render anti-HER therapies relevant beyond the HER2-positive subtype.

Abstract P1-08-15: Communication between tumor cells and fibroblasts as a prognostic factor of NACT in TNBC

Introduction. Neoadjuvant chemotherapy (NACT) is the standard of care in aggressive breast cancer, including triple negative breast cancer (TNBC). Cytotoxic drugs specifically target proliferating cells, however, patient outcome is variable. Tumor physiology and response to therapy are orchestrated by an intricate interplay between cancer, stromal and immune cells collectively forming the tumor microenvironment. We have recently uncovered a feedback mechanism of tumor cells and fibroblasts, involving IFNB1 signaling, that supports tumor cells in the recovery from chemotherapy-induced stress. Here, we wanted to assess whether targets of IFNB1 signaling in fibroblasts and tumor cells would qualify as predictive markers of pathological complete response (pCR) after neoadjuvant therapy (NACT) as prognostic markers for the course of the disease. Methods and Patients. RNA-sequencing data from in vitro experiments found the GO-term GO:0051607 ‘defense response to virus’ significantly enriched. Twentyfour genes intersected between differentially expressed genes and the genes of this GO-term. We selected three of the encoded proteins a) interferon induced with helicase C domain 1 IFIH1, b) interferon alpha-inducible protein ISG15, c) 2'-5'-oligoadenylate synthetase OAS1 to test their expression in human specimens of TNBCs after NACT by immunohistochemistry (IHC). None of the respective genes correlated with recurrence free survival when tested in treatment-naïve tumor biopsies (KM Plotter). A prospective consecutively enrolled cohort (2000 - 2021) was available with an overall pCR rate of 46%. pCR was defined by no invasive cancer cell in breast or axilla (ypT0 N0). The median follow-up for iDFS was 36.2 months (6-154) and for OS 39.3 months (6-214).Primary objective was the correlation between IFIH1, ISG15 and OAS1 protein expression in the residual tumor by non-pCR or in the tumor bed by pCR. Second objective was the association of IFIH1, ISG15 and OAS1 protein expression to invasive disease-free survival (iDFS) and overall survival (OS). Results. To date, IHC staining has been established for IFIH1, ISG15 and OAS1. In representative stainings of FFPE tissue samples with pCR we did not detect any positive signal for IFIH1 and ISG15 in stromal cells like fibroblast or lymphocytes. Slight to strong protein expression was detected by non-pCR in cancer cells, stromal cells and tumour infiltrating lymphocytes. In contrast OAS1 was expressed especially strong in lymphocytes by pCR or non-pCR. Cancer cell showed moderate OAS1 expression. IHC analysis and of the entire cohort is in progress including the analyses of the association of these markers to pCR, non-pCR and iDFS/OS. Conclusion. Using samples from our consecutive, multicentre enrolled cohort, an association between the expression of markers of an IFNB1-triggered antiviral response and pCR and survival was demonstrated in patients of the TNBC subgroup. Analysis of the entire cohort is necessary to potentially demonstrate applicability of an interferon-response as predictor of survival.

Citation Format: Marcus Bauer, Martina Vetter, Ana Maia, Efstathios Vlachavas, Brigitta Michels, Mireia Berdiel-Acer, Kathleen Schüler, Alessandra Morselli, Manio Skarlatou, Christoph Thomssen, Stefan Wiemann. Communication between tumor cells and fibroblasts as a prognostic factor of NACT in TNBC [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-08-15.

Abstract PS16-36: Paracrine signalling with stromal fibroblasts drives recovery of cancer cells after chemotherapy treatment

Introduction: The main cause of death for cancer patients is the development of metastasis. These arise mainly due to irresponsiveness of cancer cells to the administered therapy, which then fails to eliminate all cancer cells present in the patient. To overcome this problem, it is essential to understand which mechanisms are involved in the lack of treatment response. We are investigating how the tumour microenvironment (TME) affects the response of cancer cells to chemotherapy (CTX) and how it can be modulated to improve the outcome of patients to therapy. Materials and Methods: Co-culture of chemotherapy-treated breast cancer cell lines with primary fibroblasts isolated from breast cancer patients was performed to investigate if fibroblasts affect the response of tumour cells to commonly used agents, such as epirubicin and paclitaxel. Recovery of cells was assessed using colony formation assays (CFA) and cell cycle profiling by EdU and the FUCCI system. To further explore the complex crosstalk between cancer cells and fibroblasts in the context of CTX, gene expression analysis of both cell types was done using next generation sequencing. Validation and evaluation of the biological impact of the identified pathways was done using RT-qPCR, western-blot and perturbation experiments. Lastly, publicly available datasets for breast cancer were used to investigate the clinical relevance of our findings. Results and Discussion: We show that cancer cells utilize paracrine signalling with stromal fibroblasts to drive their recovery after treatment withdrawal. Cell cycle analysis and RNA-sequencing revealed an increase in cell cycle re-entry of CTX-treated cancer cells in co-culture with fibroblasts. In addition, we have successfully shown that treated cancer cells upregulate an important secreted factor that modulates fibroblasts into a pro-tumorigenic state. Moreover, analysis of human breast carcinomas supported the proposed role of the identified factor since its expression is inversely correlated with recurrence free survival (RFS). Moreover, expression of the gene signature identified in stromal fibroblasts in co-culture with CTX-treated cancer cells was equally associated with higher recurrence rates and a worse outcome in breast cancer patients. Conclusion: CTX-induced secretory profile of cancer cells orchestrates the reprogramming of stromal fibroblasts into a pro-tumorigenic state, which drives the expansion of cancer cells. Our study unravels a novel paracrine communication between cancer cells and stromal fibroblasts that ultimately results in the escape of malignant cells to treatment, highlighting the importance of the TME in drug response. Targeting of this axis could potentially improve the outcome of breast cancer patients to CTX treatment.

Citation Format: Ana Maia, Zuguang Gu, André Koch, Mireia Berdiel-Acer, Rainer Will, Matthias Schlesner, Stefan Wiemann. Paracrine signalling with stromal fibroblasts drives recovery of cancer cells after chemotherapy treatment [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS16-36.

IFNβ1 secreted by breast cancer cells undergoing chemotherapy reprograms stromal fibroblasts to support tumour growth after treatment

Chemotherapy (CTX) remains the standard of care for most aggressive tumours, including breast cancer (BC). In BC chemotherapeutic regimens, the maximum tolerated dose of cytotoxic drugs is administered at regular intervals, and cancer cells can re‐grow or adapt during the resting periods between cycles. The impact of the tumour microenvironment on the fate of cancer cells after CTX remains poorly understood. Here, we show that paracrine signalling from CTX‐treated cancer cells to stromal fibroblasts can drive cancer cell recovery after cytotoxic drug withdrawal. Interferon β1 (IFNβ1) secreted by cancer cells following treatment with high doses of CTX instigates the acquisition of an anti‐viral state in stromal fibroblasts. This state is associated with an expression pattern here referred to as interferon signature (IFNS), which encompasses several interferon‐stimulated genes (ISGs), including numerous pro‐inflammatory cytokine genes. This crosstalk is an important driver of the expansion of BC cells after CTX, and IFNβ1 blockade in tumour cells abrogated their fibroblast‐dependent recovery potential. Analysis of human breast carcinomas supported a link between CTX‐induced IFNS in tumour stroma and poor response to CTX treatment. First, IFNβ1 expression in human breast carcinomas was found to inversely correlate with recurrence free survival (RFS). Second, using laser capture microdissection data sets, we show a higher expression of IFNS in the stromal tumour compartment compared to the epithelial one and this signature was found to be more prominent in more aggressive subtypes of BC (basal‐like), pointing to a pro‐tumorigenic role of this signature. Moreover, IFNS was associated with higher recurrence rates and a worse outcome in BC patients. Our study unravels a novel form of paracrine communication between cancer cells and fibroblasts that ultimately results in CTX resistance. Targeting this axis has the potential to improve CTX outcomes in patients with BC.

Stromal NRG1 in luminal breast cancer defines pro-fibrotic and migratory cancer-associated fibroblasts

HER3 is highly expressed in luminal breast cancer subtypes. Its activation by NRG1 promotes activation of AKT and ERK1/2, contributing to tumour progression and therapy resistance. HER3-targeting agents that block this activation, are currently under phase 1/2 clinical studies, and although they have shown favorable tolerability, their activity as a single agent has proven to be limited. Here we show that phosphorylation and activation of HER3 in luminal breast cancer cells occurs in a paracrine manner and is mediated by NRG1 expressed by cancer-associated fibroblasts (CAFs). Moreover, we uncover a HER3-independent NRG1 signaling in CAFs that results in the induction of a strong migratory and pro-fibrotic phenotype, describing a subtype of CAFs with elevated expression of NRG1 and an associated transcriptomic profile that determines their functional properties. Finally, we identified Hyaluronan Synthase 2 (HAS2), a targetable molecule strongly correlated with NRG1, as an attractive player supporting NRG1 signaling in CAFs.

Noncanonical TGFβ Pathway Relieves the Blockade of IL1β/TGFβ-Mediated Crosstalk between Tumor and Stroma: TGFBR1 and TAK1 Inhibition in Colorectal Cancer

PURPOSE

The aim of the study is blocking the recruitment of a protective stroma by altering the crosstalk between normal stromal cells and tumor cells for stripping tumors of the protection conferred by the microenvironment.

EXPERIMENTAL DESIGN

A transcriptomic analysis of cocultured normal colonic fibroblasts and colorectal tumor cells was performed. We focused on the study of molecules that mediate the communication between both compartments and that entail fibroblasts' activation and the alteration of the sensitivity to chemotherapy. We identified targets for the blocking of the tumor-stroma interaction. Finally, we tested, in vivo, the blockade of the tumor-stroma interaction in orthotopic models derived from patients and in models of acquired resistance to oxaliplatin.

RESULTS

IL1β/TGFβ1 are the triggers for fibroblasts' recruitment and conversion into carcinoma-associated fibroblasts (CAF) in colorectal cancer. CAFs then secrete proinflammatory factors that alter sensitivity in tumor cells, activating JAK/STAT and PI3KCA/AKT pathways. Blocking such crosstalk with a neutralizing IL1β antibody and a TGFBR1 inhibitor is relieved by the TAK1-mediated activation of the noncanonical TGFβ pathway, which induces a change in the cytokine/chemokine repertoire that maintains a sustained activation of AKT in tumor cells. TAK1 plus TGFBR1 inhibition blocks IL1β/TGFβ1-mediated fibroblast activation, decreasing the secretion of proinflammatory cytokines. In turn, tumor cells became more sensitive to chemotherapy. In vivo, the combination of a TAK1 inhibitor plus TGFBR1 inhibitor reduced the metastatic capacity of tumor cells and the recruitment of fibroblasts.

CONCLUSIONS

Our findings provide a translational rationale for the inhibition of TAK1 and TGFBR1 to remove the chemoprotection conferred by CAFs.

Abstract 3329: Combinatorial blockade of ERBB receptors in HER2 low breast cancer

Large number of breast cancer patients clinically classified as HER2 negative, show low/moderate levels of HER2 along with other ERBB receptors. Concomitant blockade of EGFR, ERBB2 and ERBB3 with specific therapeutic antibodies (cetuximab, trastuzumab/pertuzumab and lumretuzumab, respectively) appears as a beneficial approach to improve survival of patients who have failed to previous treatment strategies. Additionally, ERBB3 expression has been reported as a trastuzumab resistance mechanism in HER2 positive subtypes.We have confirmed a specific pattern of ERBB receptors expression in different breast cancer subtypes. Individual and combined blockade of the receptors with therapeutic antibodies has been tested in vitro using a metabolic viability assay (Cell Titer Glo) and their effects in cell cycle status measured by BrdU staining. All four therapeutic antibodies bind to the respective extracellular domains inhibiting downstream signaling pathways. Response to individual treatment is cell dependent and correlates with EGFR expression in the triple negative MDA-MB-468 but not in luminal T47D cancer cell line. Response of T47D cells to lumretuzumab is higher when combined with pertuzumab or trastuzumab, suggesting ERBB2/ERBB3 dimer as the most relevant one, an effect more evident upon ectopic addition of NRG1 (only ligand for ERBB3). Long exposure of MDA-MB468 cells to cetuximab induces ERBB3 expression and increases its sensitivity to cetuximab when combined. As well as, in the HER2+ BT474 cancer cell line resistant to trastuzumab, higher levels of ERBB3 also make cells more sensitive to alternative anti-ERBB therapies. To establish the role of ERBB4 (no specific therapeutic antibody) in the whole ERBB network, stable knock-down regulation (shRNA) has been performed in T47D cells. Although treatment of HER2 overexpressing breast tumors has been successful, targeting other ERBB members in a HER2 moderate/low scenario seems to be a promising approach in combinatorial therapies; even in resistant cell lines. Thus, better characterization of ERBB network should help to pave the way for a personalized treatment of HER2 low breast cancer. [U.K.: Deceased March, 2016]

Citation Format: Mireia Berdiel-Acer, Eileen Reinz, Khalid Abnaof, Sara Burmester, Rainer Will, Ulrike Korf, Stefan Wiemann. Combinatorial blockade of ERBB receptors in HER2 low breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3329. doi:10.1158/1538-7445.AM2017-3329

A monotonic and prognostic genomic signature from fibroblasts for colorectal cancer initiation, progression, and metastasis

The differential gene expression patterns between normal colonic fibroblasts (NCF), carcinoma-associated fibroblasts from primary tumors (CAF-PT), and CAFs from hepatic metastasis (CAF-LM) are hypothesized to be useful for predicting relapse in primary tumors. A transcriptomic profile of NCF (n = 9), CAF-PT (n = 14), and CAF-LM (n = 11) was derived. Prediction Analysis of Microarrays (PAM) was used to obtain molecular details for each fibroblast class, and differentially expressed transcripts were used to classify patients according to recurrence status. A number of transcripts (n = 277) were common to all three types of fibroblasts and whose expression level was sequentially deregulated according to the transition: NCF→CAF-PT→CAF-LM. Importantly, the gene signature was able to accurately classify patients with primary tumors according to their prognosis. This capacity was exploited to obtain a refined 19-gene classifier that predicted recurrence with high accuracy in two independent datasets of patients with colorectal cancer and correlates with fibroblast migratory potential. The prognostic power of this genomic signature is strong evidence of the link between the tumor-stroma microenvironment and cancer progression. Furthermore, the 19-gene classifier was able to identify low-risk patients very accurately, which is of particular importance for stage II patients, who would benefit from the omission of chemotherapy, especially T4N0 patients, who are clinically classified as being at high risk.

IMPLICATIONS

A defined stromal gene expression signature predicts relapse in patients with colorectal cancer.

Differences between CAFs and their paired NCF from adjacent colonic mucosa reveal functional heterogeneity of CAFs, providing prognostic information

Little is known about the difference in gene expression between carcinoma-associated fibroblasts (CAFs) and paired normal colonic fibroblasts (NCFs) in colorectal cancer. Paired CAFs and NCFs were isolated from eight primary human colorectal carcinoma specimens. In culture conditions, soluble factors secreted by CAFs in the conditioned media increased clonogenicity and migration of epithelial cancer cells lines to a greater extent than did NCF. In vivo, CAFs were more competent as tumour growth enhancers than paired NCFs when co-inoculated with colorectal cell lines. Gene expression analysis of microarrays of CAF and paired NCF populations enabled us to identify 108 deregulated genes (38 upregulated and 70 downregulated genes). Most of those genes are fibroblast-specific. This has been validated in silico in dataset GSE39396 and by qPCR in selected genes. GSEA analysis revealed a differential transcriptomic profile of CAFs, mainly involving the Wnt signallingsignalling pathway, focal adhesion and cell cycle. Both deregulated genes and biological processes involved depicted a considerable degree of overlap with deregulated genes reported in breast, lung, oesophagus and prostate CAFs. These observations suggest that similar transcriptomic programs may be active in the transition from normal fibroblast in adjacent tissues to CAFs, independently of their anatomic demarcation. Additionally NCF already depicted an activated pattern associated with inflammation. The deregulated genes signature score seemed to correlate with CAF tumour promoter abilities in vitro, suggesting a high degree of heterogeneity between CAFs, and it has also prognostic value in two independent datasets. Further characterization of the roles these biomarkers play in cancer will reveal how CAFs provide cancer cells with a suitable microenvironment and may help in the development of new therapeutic targets for cancer treatment.

Lurbinectedin (PM01183), a new DNA minor groove binder, inhibits growth of orthotopic primary graft of cisplatin-resistant epithelial ovarian cancer

PURPOSE

Epithelial ovarian cancer (EOC) is the fifth leading cause of death in women diagnosed with gynecologic malignancies. The low survival rate is because of its advanced-stage diagnosis and either intrinsic or acquired resistance to standard platinum-based chemotherapy. So, the development of effective innovative therapeutic strategies to overcome cisplatin resistance remains a high priority.

EXPERIMENTAL DESIGN

To investigate new treatments in in vivo models reproducing EOCs tumor growth, we generated a preclinical model of ovarian cancer after orthotopic implantation of a primary serous tumor in nude mice. Further, matched model of acquired cisplatin-resistant tumor version was successfully derived in mice. Effectiveness of lurbinectedin (PM01183) treatment, a novel marine-derived DNA minor groove covalent binder, was assessed in both preclinical models as a single and a combined-cisplatin agent.

RESULTS

Orthotopically perpetuated tumor grafts mimic the histopathological characteristics of primary patients' tumors and they also recapitulate in mice characteristic features of tumor response to cisplatin treatments. We showed that single lurbinectedin or cisplatin-combined therapies were effective in treating cisplatin-sensitive and cisplatin-resistant preclinical ovarian tumor models. Furthermore, the strongest in vivo synergistic effect was observed for combined treatments, especially in cisplatin-resistant tumors. Lurbinectedin tumor growth inhibition was associated with reduced proliferation, increased rate of aberrant mitosis, and subsequent induced apoptosis.

CONCLUSIONS

Taken together, preclinical orthotopic ovarian tumor grafts are useful tools for drug development, providing hard evidence that lurbinectedin might be a useful therapy in the treatment of EOC by overcoming cisplatin resistance.