AL101, a gamma-secretase inhibitor, has potent antitumor activity against adenoid cystic carcinoma with activated NOTCH signaling.

Adenoid cystic carcinoma (ACC) is an aggressive salivary gland malignancy with limited treatment options for recurrent or metastatic disease. Due to chemotherapy resistance and lack of targeted therapeutic approaches, current treatment options for the localized disease are limited to surgery and radiation, which fails to prevent locoregional recurrences and distant metastases in over 50% of patients. Approximately 20% of patients with ACC carry NOTCH-activating mutations that are associated with a distinct phenotype, aggressive disease, and poor prognosis. Given the role of NOTCH signaling in regulating tumor cell behavior, NOTCH inhibitors represent an attractive potential therapeutic strategy for this subset of ACC. AL101 (osugacestat) is a potent γ-secretase inhibitor that prevents activation of all four NOTCH receptors. While this investigational new drug has demonstrated antineoplastic activity in several preclinical cancer models and in patients with advanced solid malignancies, we are the first to study the therapeutic benefit of AL101 in ACC. Here, we describe the antitumor activity of AL101 using ACC cell lines, organoids, and patient-derived xenograft models. Specifically, we find that AL101 has potent antitumor effects in in vitro and in vivo models of ACC with activating NOTCH1 mutations and constitutively upregulated NOTCH signaling pathway, providing a strong rationale for evaluation of AL101 in clinical trials for patients with NOTCH-driven relapsed/refractory ACC.

The inflammatory cytokine TNFα cooperates with Ras in elevating metastasis and turns WT-Ras to a tumor-promoting entity in MCF-7 cells.

BACKGROUND: In the present study we determined the relative contribution of two processes to breast cancer progression: (1) Intrinsic events, such as activation of the Ras pathway and down-regulation of p53; (2) The inflammatory cytokines TNFα and IL-1ß, shown in our published studies to be highly expressed in tumors of >80% of breast cancer patients with recurrent disease. METHODS: Using MCF-7 human breast tumor cells originally expressing WT-Ras and WT-p53, we determined the impact of the above-mentioned elements and cooperativity between them on the expression of CXCL8 (ELISA, qRT-PCR), a member of a "cancer-related chemokine cluster" that we have previously identified. Then, we determined the mechanisms involved (Ras-binding-domain assays, Western blot, luciferase), and tested the impact of Ras + TNFα on angiogenicity (chorioallantoic membrane assays) and on tumor growth at the mammary fat pad of mice and on metastasis, in vivo. RESULTS: Using RasG12V that recapitulates multiple stimulations induced by receptor tyrosine kinases, we found that RasG12V alone induced CXCL8 expression at the mRNA and protein levels, whereas down-regulation of p53 did not. TNFα and IL-1ß potently induced CXCL8 expression and synergized with RasG12V, together leading to amplified CXCL8 expression. Testing the impact of WT-Ras, which is the common form in breast cancer patients, we found that WT-Ras was not active in promoting CXCL8; however, TNFα has induced the activation of WT-Ras: joining these two elements has led to cooperative induction of CXCL8 expression, via the activation of MEK, NF-κB and AP-1. Importantly, TNFα has led to increased expression of WT-Ras in an active GTP-bound form, with properties similar to those of RasG12V. Jointly, TNFα + Ras activities have given rise to increased angiogenesis and to elevated tumor cell dissemination to lymph nodes. CONCLUSIONS: TNFα cooperates with Ras in promoting the metastatic phenotype of MCF-7 breast tumor cells, and turns WT-Ras into a tumor-supporting entity. Thus, in breast cancer patients the cytokine may rescue the pro-cancerous potential of WT-Ras, and together these two elements may lead to a more aggressive disease. These findings have clinical relevance, suggesting that we need to consider new therapeutic regimens that inhibit Ras and TNFα, in breast cancer patients.

Progression of luminal breast tumors is promoted by ménage à trois between the inflammatory cytokine TNFα and the hormonal and growth-supporting arms of the tumor microenvironment.

Breast cancer progression is strongly linked to inflammatory processes, aggravating disease course. The impacts of the inflammatory cytokine TNF α on breast malignancy are not fully substantiated, and they may be affected by cooperativity between TNF α and other protumoral mediators. Here, we show that together with representatives of other important arms of the tumor microenvironment, estrogen (hormonal) and EGF (growth-supporting), TNF α potently induced metastasis-related properties and functions in luminal breast tumor cells, representing the most common type of breast cancer. Jointly, TNFα + Estrogen + EGF had a stronger effect on breast cancer cells than each element alone, leading to the following: (1) extensive cell spreading and formation of FAK/paxillin-enriched cellular protrusions; (2) elevated proportion of tumor cells coexpressing high levels of CD44 and ß 1 and VLA6; (3) EMT and cell migration; (4) resistance to chemotherapy; (5) release of protumoral factors (CXCL8, CCL2, MMPs). Importantly, the tumor cells used in this study are known to be nonmetastatic under all conditions; nevertheless, they have acquired high metastasizing abilities in vivo in mice, following a brief stimulation by TNFα + Estrogen + EGF. These dramatic findings indicate that TNF α can turn into a strong prometastatic factor, suggesting a paradigm shift in which clinically approved inhibitors of TNFα would be applied in breast cancer therapy.

Inflammatory factors of the tumor microenvironment induce plasticity in nontransformed breast epithelial cells: EMT, invasion, and collapse of normally organized breast textures.

Nontransformed breast epithelial cells that are adjacent to tumor cells are constantly exposed to tumor necrosis factor-α (TNFα) and interleukin-1ß (IL-1ß), two inflammatory cytokines identified as having pro-tumoral causative roles. We show that continuous stimulation of nontransformed breast epithelial cells by TNFα + IL-1ß for 2 to 3 weeks induced their spreading and epithelial-to-mesenchymal transition (EMT). The mechanistic bases for this slow induction of EMT by TNFα + IL-1ß are: 1) it took 2 to 3 weeks for the cytokines to induce the expression of the EMT activators Zeb1 and Snail; 2) although Twist has amplified the EMT-inducing activities of Zeb1 + Snail, its expression was reduced by TNFα + IL-1ß; however, the lack of Twist was compensated by prolonged stimulation with TNFα + IL-1ß that has potentiated the EMT-inducing activities of Zeb1 + Snail. Stimulation by TNFα + IL-1ß has induced the following dissemination-related properties in the nontransformed cells: 1) up-regulation of functional matrix metalloproteinases; 2) induction of migratory and invasive capabilities; 3) disruption of the normal phenotype of organized three-dimensional acini structures typically formed only by nontransformed breast cells and spreading of nontransformed cells out of such acini. Our findings suggest that TNFα + IL-1ß induce dissemination of nontransformed breast epithelial cells and their reseeding at the primary tumor site; if, then, such detached cells are exposed to transforming events, they may form secondary malignant focus and lead to disease recurrence. Thus, our study reveals novel pathways through which the inflammatory microenvironment may contribute to relapsed disease in breast cancer.

Tumor-promoting circuits that regulate a cancer-related chemokine cluster: dominance of inflammatory mediators over oncogenic alterations.

Here, we investigated the relative contribution of genetic/signaling components versus microenvironmental factors to the malignancy phenotype. In this system, we took advantage of non-transformed fibroblasts that carried defined oncogenic modifications in Ras and/or p53. These cells were exposed to microenvironmental pressures, and the expression of a cancer-related chemokine cluster was used as readout for the malignancy potential (CCL2, CCL5, CXCL8, CXCL10). In cells kept in-culture, synergism between Ras hyper-activation and p53 dysfunction was required to up-regulate the expression of the chemokine cluster. The in vivo passage of RasHigh/p53Low-modified cells has led to tumor formation, accompanied by potentiation of chemokine release, implicating a powerful role for the tumor microenvironment in up-regulating the chemokine cluster. Indeed, we found that inflammatory mediators which are prevalent in tumor sites, such as TNFa and IL-1ß, had a predominant impact on the release of the chemokines, which was substantially higher than that obtained by the oncogenic modifications alone, possibly acting through the transcription factors AP-1 and NF-kB. Together, our results propose that in the unbiased model system that we were using, inflammatory mediators of the tumor milieu have dominating roles over oncogenic modifications in dictating the expression of a pro-malignancy chemokine readout.

Inflammatory mediators in breast cancer: coordinated expression of TNFα & IL-1ß with CCL2 & CCL5 and effects on epithelial-to-mesenchymal transition.

BACKGROUND: The inflammatory chemokines CCL2 (MCP-1) & CCL5 (RANTES) and the inflammatory cytokines TNFα & IL-1ß were shown to contribute to breast cancer development and metastasis. In this study, we wished to determine whether there are associations between these factors along stages of breast cancer progression, and to identify the possible implications of these factors to disease course. METHODS: The expression of CCL2, CCL5, TNFα and IL-1ß was determined by immunohistochemistry in patients diagnosed with: (1) Benign breast disorders (=healthy individuals); (2) Ductal Carcinoma In Situ (DCIS); (3) Invasive Ducal Carcinoma without relapse (IDC-no-relapse); (4) IDC-with-relapse. Based on the results obtained, breast tumor cells were stimulated by the inflammatory cytokines, and epithelial-to-mesenchymal transition (EMT) was determined by flow cytometry, confocal analyses and adhesion, migration and invasion experiments. RESULTS: CCL2, CCL5, TNFα and IL-1ß were expressed at very low incidence in normal breast epithelial cells, but their incidence was significantly elevated in tumor cells of the three groups of cancer patients. Significant associations were found between CCL2 & CCL5 and TNFα & IL-1ß in the tumor cells in DCIS and IDC-no-relapse patients. In the IDC-with-relapse group, the expression of CCL2 & CCL5 was accompanied by further elevated incidence of TNFα & IL-1ß expression. These results suggest progression-related roles for TNFα and IL-1ß in breast cancer, as indeed indicated by the following: (1) Tumors of the IDC-with-relapse group had significantly higher persistence of TNFα and IL-1ß compared to tumors of DCIS or IDC-no-relapse; (2) Continuous stimulation of the tumor cells by TNFα (and to some extent IL-1ß) has led to EMT in the tumor cells; (3) Combined analyses with relevant clinical parameters suggested that IL-1ß acts jointly with other pro-malignancy factors to promote disease relapse. CONCLUSIONS: Our findings suggest that the coordinated expression of CCL2 & CCL5 and TNFα & IL-1ß may be important for disease course, and that TNFα & IL-1ß may promote disease relapse. Further in vitro and in vivo studies are needed for determination of the joint powers of the four factors in breast cancer, as well as analyses of their combined targeting in breast cancer.