HIF1-alpha functions as a tumor promoter in cancer associated fibroblasts, and as a tumor suppressor in breast cancer cells : Autophagy drives compartment-specific oncogenesis

Our recent studies have mechanistically implicated a loss of stromal Cav-1 expression and HIF1-alpha-activation in driving the cancer-associated fibroblast phenotype, through the paracrine production of nutrients via autophagy and aerobic glycolysis. However, it remains unknown if HIF1a-activation is sufficient to confer the cancer-associated fibroblast phenotype. To test this hypothesis directly, we stably-expressed activated HIF1a in fibroblasts and then examined their ability to promote tumor growth using a xenograft model employing human breast cancer cells (MDA-MB-231). Fibroblasts harboring activated HIF1a showed a dramatic reduction in Cav-1 levels and a shift towards aerobic glycolysis, as evidenced by a loss of mitochondrial activity, and an increase in lactate production. Activated HIF1a also induced BNIP3 and BNIP3L expression, markers for the autophagic destruction of mitochondria. Most importantly, fibroblasts expressing activated HIF1a increased tumor mass by ∼2-fold and tumor volume by ∼3-fold, without a significant increase in tumor angiogenesis. In this context, HIF1a also induced an increase in the lymph node metastasis of cancer cells. Similar results were obtained by driving NFκB activation in fibroblasts, another inducer of autophagy. Thus, activated HIF1a is sufficient to functionally confer the cancer-associated fibroblast phenotype. It is also known that HIF1a expression is required for the induction of autophagy in cancer cells. As such, we next directly expressed activated HIF1a in MDA-MB-231 cells and assessed its effect on tumor growth via xenograft analysis. Surprisingly, activated HIF1a in cancer cells dramatically suppressed tumor growth, resulting in a 2-fold reduction in tumor mass and a 3-fold reduction in tumor volume. We conclude that HIF1a activation in different cell types can either promote or repress tumorigenesis. Based on these studies, we suggest that autophagy in cancer-associated fibroblasts promotes tumor growth via the paracrine production of recycled nutrients, which can directly "feed" cancer cells. Conversely, autophagy in cancer cells represses tumor growth via their "self-digestion". Thus, we should consider that the activities of various known oncogenes and tumor-suppressors may be compartment and cell-type specific, and are not necessarily an intrinsic property of the molecule itself. As such, other "classic" oncogenes and tumor suppressors will have to be re-evaluated to determine their compartment specific effects on tumor growth and metastasis. Lastly, our results provide direct experimental support for the recently proposed "Autophagic Tumor Stroma Model of Cancer".

Medienart:

E-Artikel

Erscheinungsjahr:

2010

Erschienen:

2010

Enthalten in:

Zur Gesamtaufnahme - volume:9

Enthalten in:

Cell cycle (Georgetown, Tex.) - 9(2010), 17 vom: 01. Sept., Seite 3534-51

Sprache:

Englisch

Beteiligte Personen:

Chiavarina, Barbara [VerfasserIn]
Whitaker-Menezes, Diana [VerfasserIn]
Migneco, Gemma [VerfasserIn]
Martinez-Outschoorn, Ubaldo E [VerfasserIn]
Pavlides, Stephanos [VerfasserIn]
Howell, Anthony [VerfasserIn]
Tanowitz, Herbert B [VerfasserIn]
Casimiro, Mathew C [VerfasserIn]
Wang, Chenguang [VerfasserIn]
Pestell, Richard G [VerfasserIn]
Grieshaber, Philip [VerfasserIn]
Caro, Jaime [VerfasserIn]
Sotgia, Federica [VerfasserIn]
Lisanti, Michael P [VerfasserIn]

Themen:

BNIP3 protein, human
BNIP3L protein, human
Caveolin 1
Hypoxia-Inducible Factor 1, alpha Subunit
Journal Article
Lactates
Membrane Proteins
NF-kappa B
Proto-Oncogene Proteins
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Tumor Suppressor Proteins

Anmerkungen:

Date Completed 24.01.2011

Date Revised 21.03.2022

published: Print-Electronic

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM201793210