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In vivo anti‐V‐ATPase antibody treatment delays ovarian tumor growth by increasing antitumor immune responses
Journal article   Open access   Peer reviewed

In vivo anti‐V‐ATPase antibody treatment delays ovarian tumor growth by increasing antitumor immune responses

Arpita Kulshrestha, Gajendra K Katara, Safaa A Ibrahim, Valerie E Riehl, Sylvia Schneiderman, Mahmood Bilal, Alexandria N Young, Shayna Levine, Sara Fleetwood, James Dolan, …
Molecular oncology, Vol.14(10), pp.2436-2454
10/2020
DOI: 10.1002/1878-0261.12782
PMCID: PMC7530789
PMID: 32797726
url
https://doi.org/10.1002/1878-0261.12782View
Published (Version of record) Open Access

Abstract

Tumor acidity is the key metabolic feature promoting cancer progression by eliciting immune‐suppression. V‐ATPases on a cancer cell's surface pump out excess protons and acidify the tumor microenvironment (TME). In vivo treatment of ovarian tumors using a monoclonal antibody (a2v‐mAb) directed against V‐ATPase‐V0a2 delays tumor growth by enhancing antitumor immune responses, making it an effective treatment strategy in ovarian cancer. Tumor acidity is the key metabolic feature promoting cancer progression and is modulated by pH regulators on a cancer cell's surface that pump out excess protons/lactic acid for cancer cell survival. Neutralizing tumor acidity improves the therapeutic efficacy of current treatments including immunotherapies. Vacuolar‐ATPase (V‐ATPase) proton pumps encompass unique plasma membrane‐associated subunit isoforms, making this molecule an important target for anticancer therapy. Here, we examined the in vivo therapeutic efficacy of an antibody (a2v‐mAB) targeting specific V‐ATPase‐‘V0a2’ surface isoform in controlling ovarian tumor growth. In vitro a2v‐mAb treatment inhibited the proton pump activity in ovarian cancer (OVCA) cells. In vivo intraperitoneal a2v‐mAb treatment drastically delayed ovarian tumor growth with no measurable in vivo toxicity in a transplant tumor model. To explore the possible mechanism causing delayed tumor growth, histochemical analysis of the a2v‐mAb‐treated tumor tissues displayed high immune cell infiltration (M1‐macrophages, neutrophils, CD103 + cells, and NK cells) and an enhanced antitumor response (iNOS, IFN‐y, IL‐1α) compared to control. There was marked decrease in CA‐125‐positive cancer cells and an enhanced active caspase‐3 expression in a2v‐mAb‐treated tumors. RNA‐seq analysis of a2v‐mAb tumor tissues further revealed upregulation of apoptosis‐related and toll‐like receptor pathway‐related genes. Indirect coculture of a2v‐mAb‐treated OVCA cells with human PBMCs in an unbuffered medium led to an enhanced gene expression of antitumor molecules IFN‐y, IL‐17, and IL‐12‐A in PBMCs, further validating the in vivo antitumor responses. In conclusion, V‐ATPase inhibition using a monoclonal antibody directed against the V0a2 isoform increases antitumor immune responses and could therefore constitute an effective treatment strategy in OVCA.
 Ovarian Cancer a2 isoform monoclonal antibody Research Articsles vacuolar‐ATPase

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