Defining the role of melanoma-associated B cells
The tumor microenvironment (TME) critically controls tumor growth, progression and therapy responses of tumors. B cells are capable to stimulate or dampen immune responses and B cells are part of the TME in human melanomas but their functional role is largely unknown. Tumor-associated B cells (TAB) have been shown to promote tumor growth and therapy resistance in several animal tumor models.
We have now described a mechanism of acquired drug resistance in melanoma through the tumor microenvironment, which is mediated by human tumor-associated B-cells: human melanoma cells constitutively produce the growth factor FGF-2, which activates tumor-infiltrating B-cells to produce the growth factor IGF-1. B-cell-derived IGF-1 is critical for resistance of melanomas to BRAF- and MEK-inhibitors due to emergence of heterogeneous subpopulations and activation of FGFR-3. Furthermore, first clinical data from a pilot trial in therapy-resistant metastatic melanoma patients show anti-tumor activity through B-cell depletion by the anti-CD20 antibody ofatumumab.
In line with these data we have previously shown in another small pilot trial, that the anti-CD20 antibody rituximab, when given in an adjuvant setting, prolongs the recurrence-free interval (RFI) and overall survival (OS) of melanoma patients with stage IV metastatic disease.
On the other hand, we have robust complementary protein and RNA data that increased B cell numbers in untreated primary and metastatic melanomas are associated with a better overall survival.
We could now identify a subgroup of melanoma patients where TAB induce therapy resistance and have a negative impact on overall survival. We will follow up this group of patients to identify the underlying mechanisms, including the bidirectional communication with melanoma cells as well as the cross-talk to other TME-cell types.
- Pinc A, Somasundaram R, Wagner C, Hörmann M, Karanikas G, Jalili A, Bauer W, Brunner P, Grabmeier-Pfistershammer K, Gschaider M, Lai C-Y, Hsu M-Y, Herlyn M, Stingl G, Wagner SN (2012) Targeting CD20 in melanoma patients at high risk of disease recurrence. Mol Ther 20:1056-62
- Garg G, Maurer M, Griss J, Brueggen MC, Wolf IH, Wagner C, Willi N, Mertz KD, Wagner SN (2016) Tumor associated B cells in cutaneous primary melanoma and improved clinical outcome. Human Pathol. doi.org/10.1016/j.humpath.2016 03.022
- Somasundaram R, Zhang G, Fukunaga-Kalabis M, Perego M, Krepler C, Xu X, Wagner C, Hristova D, Zhang J, Tian T, Wei, Z, Liu Q, Garg K, Griss J, Hards R, Maurer M, Hafner C, Mayerhöfer M, Karanikas G, Jalili A, Bauer-Pohl V, Weihsengruber F, Rappersberger K, Koller J, Lang R, Hudgens C, Chen G, Tetzlaff M, Wu L, Tompers-Frederick D, Scolyer RA, Long GV, Damle M, Ellingsworth C, Grinman L, Choi H, Gavin BJ, Dunagin M, Raj A, Scholler N, Gross L, Beqiri M, Bennett KL, Watson I, Schaider H, Davies MA, Wargo J, Czerniecki BL, Schuchter L, Herlyn D, Flaherty K, Herlyn M, Wagner SN (2017) Tumor-associated B cells induce tumor heterogeneity and therapy resistance. Nature Commun. DOI: 10.1038/s41467-017-00452-4
Characterization of melanoma subpopulations
In the past decades clinical cancer research has mainly focused on the development and identification of drugs targeting the bulk of cancer cells, while neglecting distinct subpopulations. Melanoma tumors do contain several subpopulations including CD20-, CD271-, CD133-, ABCB5- and JARID1B- expressing ones. These small and temporarily distinct subpopulations, of which some have tumor initiating and/or maintaining properties, contribute to resistance against and/or recurrence of the disease after therapy. Therefore, these subpopulations require distinct targeting for full and consistent eradication of the tumor.
The molecular mechanism underlying the induction of some of these melanoma subpopulations and key molecules driving this mechanism are currently subject to research in our laboratory. Identification and functional characterization of these key molecules, activated signaling pathways and/or transcription factors are essential for the identification of novel therapeutic vulnerabilities. At the moment we are screening novel and conventional drug targets in in vitro surrogate assays of drug sensitivity.
- Perego M, Maurer M, Shaffer S, Müller AC, Parapatics K, Bennett KL, Li L, Wang J, Hristova D, Shin S, Keeney, F, Liu, S, Xu X, Raj, A, Jensen JK, Wagner SN, Somasundaram R, Herlyn M (2017) Slow-cycling melanoma cells are invasive through a SerpinE2-dependent mechanism. Oncogene. doi: 10.1038/onc.2017.341
Identification of molecular subtypes in melanoma
Melanoma is a heterogeneous cancer comprising several genetic subtypes, which are characterized by a distinct gene expression signature associated with a special biological behavior. In addition to our significantly contributions to the detection of recurrent genetic mutations as part of the “TCGA cancer gene atlas” initiative, we developed and utilized an Integrative Detection of Genetic Outliers (INDEGO) approach to identify genes with an expression outlier profile in human melanoma samples. An outlier profile is an observation that is numerically distant from the rest of the data and should be characteristic for genes expressed in only a subgroup but not the majority of tumor samples. Using this approach we could describe two novel protumorigenic genes in melanoma, namely MTSS1 as metastasis driver and SSR2 as a prosurvival gene mediating increased stress response.
- Hodis E, Watson IR, Kryukov GV, Arold ST, Imielinski M, Theurillat JP, Nickerson E, Auclair D, Li L, Place C, DiCara D, Ramos AH, Lawrence MS, Cibulskis K, Sivachenko A, Voet D, Saksena G, Stransky N, Onofrio RC, Winckler W, Ardlie K, Wagle N, Wargo J, Chong K, Morton DL, Stemke-Hale K, Chen G, Noble M, Meyerson M, Ladbury JE, Davies MA, Gershenwald JE, Wagner SN, Hoon DSB, Schadendorf D, Lander ES, Gabriel SB, Getz G, Garraway LA, Chin L (2012) A Landscape of Driver Mutations in Melanoma. Cell. 150:251-63
- Berger MR, Heffernan TP, Lawrence MS, Protopopov A, Ivanova E, Ghosh P, Zhang H, Cibulskis K, Sivachenko AY, Sucker A, Sougnez C, Onofrio R, Ambrogio L, Fennell T, Carter SL, Drier Y, Singer MA, Voet D, Jing R, Saksena G, Ramos AH, Pugh TJ, Parkin M, Wilkinson J, Fisher S, Winckler W, Mahan S, Ardlie K, Baldwin J, Schadendorf D, Meyerson M, Bagriel SB, Golub TR, Wagner SN, Lander ES, Getz G, Chin L, Garraway LA (2012) Melanoma genome sequencing reveals frequent PREX2 mutations. Nature. 485:502-6
- Mertz, KD, Pathria G, Wagner C, Saarikangas J, Sboner A, Romanov J, Gschaider M, Lenz F, Neumann F, Schreiner W, Nemethova M, Glassmann A, Lappalainen P, Stingl G, Small VJ, Fink D, Chin L, Wagner SN (2014) MTSS1 is a Metastasis Driver in a Subset of Human Melanomas. Nature Commun. 5:3465
- Garg B, Pathria G, Wagner C, Maurer M, Wagner SN (2016) Signal Sequence Receptor 2 is required for survival of human melanoma cells as part of an Unfolded Protein Response to endoplasmic reticulum stress. Mutagenesis, doi:10.1093/mutage/gew023
Most recent projects
Towards therapeutic targeting of MITF-dependent signaling pathways in melanoma
The transcription factor MITF is a master regulator of melanocyte differentiation and survival. A significant proportion of melanomas has been shown to harbor an amplification and/or mutation of this gene, implicating MITF as a lineage-specific oncogene. As direct chemical targeting of MITF remains a challenge, we identified druggable targets/pathways as potential new therapeutic targets in MITF-driven melanoma.
- Borgdorff V, Rix U, Winter GE, Gridling M, Müller AC, Breitwieser FP, Wagner C, Colinge J, Bennett KL, Superti-Furga G, Wagner SN (2013) A Chemical Biology Approach Identifies AMPK as a Modulator of Melanoma Oncogene MITF. Oncogene. Jun 3. doi: 10.1038/onc.2013.185
- Pathria G, Garg B, Borgdorff V, Garg K, Wagner C, Wagner SN (2016) Bypassing MITF-conferred Drug Resistance through Dual AURKA/MAPK Targeting. Cell Death & Disease. 7, e2135 doi:10.1038/cddis.2015.369
Overcoming drug resistance in melanoma
Melanoma responses to BRAFV600E inhibition are often followed by disease recurrence through reactivation of the mitogen-activated protein kinase (MAPK) pathway at different levels. Here, we are evaluating inhibition of downstream effectors or inhibitors of MAPK signaling as a potential therapeutic strategy for treatment of BRAFV600E inhibitor-resistant melanomas. In the meanwhile we could identify INK4- and Cip/Kip-dependent pathways as downstream nuclear effectors and novel therapeutic targets.
- Jalili A, Wagner C, Pashenkov M, Pathria G, Mertz KD, Widlund HR, Lupien M, Brunet JP, Golub TR, Stingl G, Fisher DE, Ramaswamy S, Wagner SN (2012) Dual suppression of INK4- and Cip/Kip-dependent pathways in human melanoma. J Natl Cancer Inst. 104:1673-9
Revelation of novel mechanisms of melanoma cell biology and delineated therapeutic targets
We identified four key components of the nucleocytoplasmic transport machinery -CRM1, RAN (RAN-GTPase), RANGAP1, and RANBP1- to be overexpressed in human melanoma metastases. Chromosome region maintenance 1 (CRM1) inhibition induced a marked depletion of prosurvival/cytoplasmic extracellular signal-regulated kinase 1/2 (Erk1/2) and p90 ribosomal S6 kinase1 and elicited persistent Erk-signaling and hyperactivation. Consistently, CRM1 inhibition inflicted extensive apoptosis in melanoma cells. In addition, we could show that CRM1 cofactor RanBP3 is required for melanoma cell proliferation and survival f.e. via providing nuclear exit of the weak nuclear export sequence-harboring extracellular signal-regulated kinase protein. Together these data describe for the first time interference with the nucleocytoplasmic transport as a mechanism to inhibit oncogene signaling in cancer.
- Pathria G, Wagner C, Wagner SN (2012) Inhibition of CRM1-mediated nucleocytoplasmic transport: a novel approach to trigger human melanoma cell apoptosis by perturbing multiple cellular pathways. J Invest Dermatol. 132:2780-90
- Pathria G, Garg B, Wagner C, Garg K, Gschaider M, Jalili A, Wagner SN (2016) RanBP3 Regulates Melanoma Cell Proliferation via Selective Control of Nucleocytoplasmic Transport. J Invest Dermatol, 136;264-74
Identification (and functional characterization) of >25 novel therapeutic targets in human melanoma
last 6 years:
- 2012: Publication of “The Landscape of Driver Mutations in Melanoma”-Gene Atlas, founding member of the consortium
- 2012: Identification of INK4- and Cip/Kip-dependent pathways as therapeutic targets to overcome MAPKi-associated drug resistance
- 2012: First description of interference with the nucleocytoplasmic transport as a mechanism to inhibit oncogene signaling in cancer
- 2012: First Investigator-initiated clinical trial to show anti-tumor activity of adjuvant CD20 immunotargeting in stage IV melanoma patients
- 2013: Description of novel signaling pathways for interference with MITF’s oncogene function in melanoma
- 2014: Identification of MTSS1 as a metastasis driver in a subset of primary human melanomas
- 2015: First description of RanBP3 as a regulator of nuclear MAPK activity
- 2016: Identification of novel therapeutic targets to interfere with MITF-conferred drug resistance in melanoma
- 2017: Completion of the first clinical trial about CD20 immunotargeting in stage IV melanoma patients with established metastatic disease showing clinical anti-tumor activity
- 2017: First description of tumor associated B cells to support human melanoma growth and therapy resistance