Maximum inhibition of breast cancer/stem cell growth by concomitant blockage of key receptors

Abstract

The blockage of cancer cell growth and division is the prime objective in clinical cancer therapy both at early stages and for inhibition of minimal residual disease and relapse. The failure of conventional therapies in treating breast cancer (BC) has prompted dissection of signalling pathways involved in BC cell growth and characterisation of cellular receptors. Specific sets of membrane-bound receptors promote disarrayed self-renewal of BC stem cells and deregulated BC cell proliferation. Individual blockage of each receptor promotes only incomplete inhibition of BC cell growth and partial regression of metastasis. Such monotherapies are based on either chemotherapy or monoclonal antibodies. However, they do not provide long-lasting benefits and are further compromised by increasing resistance the cancer cells acquire against therapeutic agents, by their evasion of receptor blockage and by adoption of alternative growth routes that are induced by cross-talks between key receptors. On the other hand, dual targeting approaches, including receptor blockage combined with chemotherapy, produce prolonged overall survival but, nevertheless, complicate treatment by inducing side effects. Based on the complex nature of BC, combined targeted strategies that potentially confer maximum coverage for treatment cannot be effective without overcoming drug resistance initiated and further induced by inter-receptor communications. This implies that a comprehensive strategy based on concomitant inhibition of key receptors could provide an ultimate solution for effective treatment of aggressive types of BC. Such a strategy would likely be capable of targeting breast tumour cells and BC stem cells alike eventually forcing the cancer to regress.