EphA3 as a target for antibody immunotherapy in acute lymphoblastic leukemia.

The human EphA3 gene was discovered in a pre-B acute lymphoblastic leukemia (pre-B-ALL) using the EphA3-specific monoclonal antibody (mAb), IIIA4, which binds and activates both human and mouse EphA3. We use two models of human pre-B-ALL to examine EphA3 function, demonstrating effects on pre-B-cell receptor signaling. In therapeutic targeting studies, we demonstrated antitumor effects of the IIIA4 mAb in EphA3-expressing leukemic xenografts and no antitumor effect in the xenografts with no EphA3 expression providing evidence that EphA3 is a functional therapeutic target in pre-B-ALL. Here we show that the therapeutic effect of the anti-EphA3 antibody was greatly enhanced by adding an α-particle-emitting 213Bismuth payload.

Meta-analysis of the global gene expression profile of triple-negative breast cancer identifies genes for the prognostication and treatment of aggressive breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype lacking expression of estrogen and progesterone receptors (ER/PR) and HER2, thus limiting therapy options. We hypothesized that meta-analysis of TNBC gene expression profiles would illuminate mechanisms underlying the aggressive nature of this disease and identify therapeutic targets. Meta-analysis in the Oncomine database identified 206 genes that were recurrently deregulated in TNBC compared with non-TNBC and in tumors that metastasized or led to death within 5 years. This 'aggressiveness gene list' was enriched for two core functions/metagenes: chromosomal instability (CIN) and ER signaling metagenes. We calculated an 'aggressiveness score' as the ratio of the CIN metagene to the ER metagene, which identified aggressive tumors in breast cancer data sets regardless of subtype or other clinico-pathological indicators. A score calculated from six genes from the CIN metagene and two genes from the ER metagene recapitulated the aggressiveness score. By multivariate survival analysis, we show that our aggressiveness scores (from 206 genes or the 8 representative genes) outperformed several published prognostic signatures. Small interfering RNA screen revealed that the CIN metagene holds therapeutic targets against TNBC. Particularly, the inhibition of TTK significantly reduced the survival of TNBC cells and synergized with docetaxel in vitro. Importantly, mitosis-independent expression of TTK protein was associated with aggressive subgroups, poor survival and further stratified outcome within grade 3, lymph node-positive, HER2-positive and TNBC patients. In conclusion, we identified the core components of CIN and ER metagenes that identify aggressive breast tumors and have therapeutic potential in TNBC and aggressive breast tumors. Prognostication from these metagenes at the mRNA level was limited to ER-positive tumors. However, we provide evidence that mitosis-independent expression of TTK protein was prognostic in TNBC and other aggressive breast cancer subgroups, suggesting that protection of CIN/aneuploidy drives aggressiveness and treatment resistance.

Mutant p53 drives multinucleation and invasion through a process that is suppressed by ANKRD11.

Mutations of p53 in cancer can result in a gain of function associated with tumour progression and metastasis. We show that inducible expression of several p53 'hotspot' mutants promote a range of centrosome abnormalities, including centrosome amplification, increased centrosome size and loss of cohesion, which lead to mitotic defects and multinucleation. These mutant p53-expressing cells also show a change in morphology and enhanced invasive capabilities. Consequently, we sought for a means to specifically target the function of mutant p53 in cancer cells. This study has identified ANKRD11 as a key regulator of the oncogenic potential of mutant p53. Loss of ANKRD11 expression with p53 mutation defines breast cancer patients with poor prognosis. ANKRD11 alleviates the mitotic defects driven by mutant p53 and suppresses mutant p53-mediated mesenchymal-like transformation and invasion. Mechanistically, we show that ANKRD11 restores a native conformation to the mutant p53 protein and causes dissociation of the mutant p53-p63 complex. This represents the first evidence of an endogenous protein with the capacity to suppress the oncogenic properties of mutant p53.

Harnessing the complexity of DNA-damage response pathways to improve cancer treatment outcomes.

The DNA-damage response (DDR) pathways consist of interconnected components that respond to DNA damage to allow repair and promote cell survival. The DNA repair pathways and downstream cellular responses have diverged in cancer cells compared with normal cells because of genetic alterations that underlie drug resistance, disabled repair and resistance to apoptosis. Consequently, abrogating DDR pathways represents an important mechanism for enhancing the therapeutic index of DNA-damaging anticancer agents. In this review, we discuss the DDR pathways that determine antitumor effects of DNA-damaging agents with a specific focus on treatment outcomes in tumors carrying a defective p53 pathway. Finely tuned survival and death pathways govern the cellular responses downstream of the cytotoxic insults inherent in anticancer treatment. The significance and relative contributions of cellular responses including apoptosis, mitotic catastrophe and senescence are discussed in relation to the web of molecular interactions that affect such outcomes. We propose that promising combinations of DNA-damaging anticancer treatments with DDR-pathway inhibition would be further enhanced by activating downstream apoptotic pathways. The proposed rationale ensures that actual cell death is the preferred outcome of cancer treatment instead of other responses, including reversible cell cycle arrest, autophagy or senescence. Finally, to better measure the contribution of different cellular responses to anticancer treatments, multiplex in vivo assessments of therapy-induced response pathways such as cell death, senescence and mitotic catastrophe is desirable rather than the current reliance on the measurement of a single response pathway such as apoptosis.