Blocking the attachment of cancer cells in vivo with DNA aptamers displaying anti‐adhesive properties against the carcinoembryonic antigen

Abstract

The formation of metastatic foci occurs through a series of cellular events, initiated by the attachment and aggregation of cancer cells leading to the establishment of micrometastases. We report the derivation of synthetic DNA aptamers bearing anti‐adhesive properties directed at cancer cells expressing the carcinoembryonic antigen (CEA). Two DNA aptamers targeting the homotypic and heterotypic IgV‐like binding domain of CEA were shown to block the cell adhesion properties of CEA, while not recognizing other IgV‐like domains of CEACAM family members that share strong sequence and structural homologies. More importantly, the pre‐treatment of CEA‐expressing tumour cells with these aptamers prior to their intraperitoneal implantation resulted in the prevention of peritoneal tumour foci formation. Taken together, these results highlight the effectiveness of targeting the cell adhesion properties of cancer cells with aptamers in preventing tumour implantation.

Serum‐derived carcinoembryonic antigen (CEA) activates fibroblasts to induce a local re‐modeling of the extracellular matrix that favors the engraftment of CEA‐expressing tumor cells

“…Changes in adherence and proliferation of CEA null and CEA‐expressing colon cancer cells were also determined by dispensing LS174T, HT‐29, MC38 cells (2.0 × 10 4 cells per well) into sensor plates (E‐plates; ACEA Biosciences Inc.) pre‐equilibrated with conditioned medium from stimulated and non‐stimulated HNNFb cultures. Changes in relative impedance were measured at 1‐min intervals, over the course of 48 hr …”

“…Suspensions of HeLa.CEA (2.0 × 10 4 cells) were dispensed into sensor plates (E‐plates; ACEA Biosciences Inc.) pre‐equilibrated with either HNNFb conditioned medium or conditioned medium supplemented with cRGD (200 µM; Sigma‐Aldrich), miltefosine (100 µM; Sigma‐Aldrich), conA (80 µg/ml; Sigma‐Aldrich) or anti‐CEA N domain pAb (1:100 final dilution; 3). Loss of cell adherence was measured as a decrease in relative impedance recorded at 1‐min intervals over the course of 24 hr …”

“…An understanding of molecular determinants driving the progression of cancer to a metastatic stage remains limited, thus outlining the complexity of events leading to tumor implantation and the formation of micrometastases. Components responsible for intercellular and cell‐matrix adhesion events involving tumor cells have been shown to serve an important role in the formation as well as expansion of metastatic foci . Currently, few tumor‐derived soluble factors have been identified as causal agents leading to the initiation or the progression of the metastatic cascade.…”

DNA aptamer technology for personalized medicine

“…For example, a serum-stabilized DNA aptamer for immunotherapy of CD30-expressing lymphoma was generated [33]. In addition, two DNA aptamers which bind to carcinoembryonic antigen (CEA) were selected and used for the pre-treatment of a CEA-expressing tumor model in vivo [34]. Moreover, a DNA aptamer recognizing human epidermal growth factor receptor 2 (ErbB-2/HER2) was recently shown to have antitumor efficacy two-fold higher than a corresponding monoclonal anti-ErbB-2/HER2 antibody, in both human gastric cancer cells and in mice bearing tumor xenographs [35].…”

Induction of antigen‐specific TH9 immunity accompanied by mast cell activation blocks tumor cell engraftment

“…To address these issues, we recently developed an alternate vaccination approach against CEA that results instead in a focused IgG response towards its IgV‐like N domain and blocks both homotypic (N and A 3 domains of CEA) and heterotypic (fibronectin, ECM) interactions responsible for the implantation of disseminated tumor cells . This novel vaccine strategy was based on the finding that disrupting CEA N domain‐specific interactions with domain‐specific antibodies, aptamers or soluble recombinant CEA N (rCEA N) or A 3 modules reduces the engraftment of CEA‐expressing tumor cells as well as the formation and expansion of tumor foci in vivo . Vaccinating CEA transgenic mice (CEA.Tg) with a recombinant, nonglycosylated form of the CEA Ig V‐like N domain combined with poly I:C, as an adjuvant, led to the production of circulating antibodies exhibiting anti‐adhesive as well as cytocidal properties (ADCC, CDC), which blocked the lodging and formation of CEA‐expressing murine tumor foci in the lungs and peritoneal cavity of vaccinated CEA.Tg mice .…”