MMP-7 nanosensors for urine-based detection of chemotherapy-induced senescence and pulmonary fibrosis

Abstract

Lung cancer is a debilitating disease with poor survival rates, causing nearly 1.7 million deaths annually. Senescence is a cellular response to irreparable damage consisting of the implementation of a stable cell cycle arrest and pro-inflammatory activity via the secretion of senescence-associated secretory phenotype (SASP). Senescence is considered a fundamental tumour suppression mechanism to prevent the expansion of oncogenically-stressed premalignant cells, including in lung cancer. When senescent cells accumulate in tissues, however, they can also play a detrimental role in the early tumour microenvironment by distinct paracrine activities promoting lung cancer initiation, progression, and relapse, as validated in several mouse cancer models and clinical samples. In addition, standard-of-care treatment modalities used to intervene in cancer can induce senescence in tumour cells and cause therapy resistance. Therefore, detecting therapy-induced senescence is vital for monitoring treatment responses, identifying potential tumour progression, and tailoring patient-specific interventions with senotherapies. However, current in vivo senescence detection methods necessitate invasive tissue biopsies or surgeries. These methods are not always plausible to perform and carry morbidity risks, highlighting the need for non-invasive longitudinal methods. This thesis describes development of an innovative and non-invasive platform for detecting therapy-induced senescence from patient’s urine. By employing lung cancer models in vitro and in vivo, as well as tumour specimens from non-small cell lung cancer patients, matrix metalloproteinase-7 (MMP-7) was identified as unique metalloprotease secreted by chemotherapy-induced senescent lung cancer cells (Chapter 4). This protease was then utilised to develop an ALBANC nanosensor (Figure 1), comprising human serum albumin covalently linked to 1.6-nm gold nanoclusters (AuNCs) by MMP-7-cleavable peptides (Chapter 5). When injected intravenously, the nanosensor is cleaved by MMP-7 in senescence-enriched tissues or serum, resulting in the release of AuNCs into urine. Highly sensitive and rapid (completed within 20 min) colourimetric assays were developed for AuNC detection in the urine (Chapter 6). Finally, Chapter 7 presents the results of in vivo validation by employing a lung cancer xenograft mouse model, showing that the designed nanosensor could sensitively and specifically detect cisplatin-induced senescence within tumours. In addition, it could be used to detect lung fibrosis, a condition associated with elevated levels of MMP-7, in a mouse model. In summary, this work introduces a simple, versatile, and non-invasive sensing platform for colourimetric and spectroscopic detection of therapy-induced senescence from urine by monitoring senescence-specific protease activity. ALBANC nanosensor presented a significant advancement in the detection of diseases associated with aberrant protease activity, such as senescence and fibrosis, and could be easily adapted to other disease models, other proteases, and senescence-associated diseases.