ABSTRACT
BACKGROUND: Small cell lung cancer (SCLC) is the most aggressive type of lung cancer. The overall survival has not improved significantly over the last decades because no major therapeutic breakthroughs have been achieved for over 15 years. METHODS: We analyzed a genome-wide loss-of-function screening database to identify vulnerabilities in SCLC for the development of urgently needed novel therapies. RESULTS: We identified SKP2 (encoding S-phase kinase-associated protein 2) and CKS1B (encoding CDC28 protein kinase regulatory subunit 1B) as the two most essential genes in that order in SCLC. Notably, SKP2 and CKS1B comprise the p27 binding pocket of the E3 ubiquitin ligase SCFSKP2 complex. Immunohistochemistry on tissue microarrays revealed that SKP2 was expressed in >95% of samples at substantially higher levels than that observed for commonly used neuroendocrine markers. As expected, SCLC cell lines were sensitive to SKP2 inhibition. Furthermore, SKP2 or CKS1B knockdown induced apoptosis in RB1 mutant cells, whereas it induced senescence in RB1 wild-type cells. CONCLUSION: Although the mechanism underlying SKP2 knockdown-induced growth inhibition differs between RB1-wild-type and -mutant SCLC, SKP2 can be considered a novel therapeutic target for patients with SCLC regardless of the RB1 mutation status. Our findings indicate that SKP2 is a potential novel clinical diagnostic marker and therapeutic target in SCLC.
ABSTRACT
We report a case of a 62-year-old male who was diagnosed with advanced rectal cancer. The attending gastro-enterologist initiated chemotherapy using capecitabine plus oxaliplatin and bevacizumab; however, this treatment regimen was discontinued, as the patient developed a skin rash. Once the skin rash improved, chemotherapy was re-initiated using a combination of trifluridine and tipiracil hydrochloride (TAS-102). The patient developed high fever and dyspnea 2 months after initiation of TAS-102. Chest high-resolution computed tomography showed bilateral diffuse ground glass opacities in all lung lobes with traction bronchiectasis. At this time, the gastro-enterologist consulted our department. The patient was put on non-invasive positive pressure ventilation due to worsening respiratory symptoms. The patient was suspected to develop TAS-102-induced interstitial pneumonia based on positive TAS-102 drug-induced lymphocyte stimulation test. The patient's respiratory symptoms and radiological findings improved after corticosteroid treatment. The corticosteroid dose was gradually decreased by 5 mg. Thereafter, chemotherapy was re-initiated using different anti-cancer agents.