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Background Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease with few effective therapeutic options. Recently, drug repositioning, which involves identifying novel therapeutic potentials for existing drugs, has been popularized as a new approach for the development of novel therapeutic reagents. However, this approach has not yet been fully utilized in the field of pulmonary fibrosis. Methods The present study identified novel therapeutic options for pulmonary fibrosis using a systematic computational approach for drug repositioning based on integration of public gene expression signatures of drug and diseases (in silico screening approach). Results Among the top compounds predicted to be therapeutic for IPF by the in silico approach, we selected BI2536, a polo-like kinase (PLK) 1/2 inhibitor, as a candidate for treating pulmonary fibrosis using an in silico analysis. However, BI2536 accelerated mortality and weight loss rate in an experimental mouse model of pulmonary fibrosis. Because immunofluorescence staining revealed that PLK1 expression was dominant in myofibroblasts while PLK2 expression was dominant in lung epithelial cells, we next focused on the anti-fibrotic effect of the selective PLK1 inhibitor GSK461364. Consequently, GSK461364 attenuated pulmonary fibrosis with acceptable mortality and weight loss in mice. Conclusions These findings suggest that targeting PLK1 may be a novel therapeutic approach for pulmonary fibrosis by inhibiting lung fibroblast proliferation without affecting lung epithelial cells. In addition, while in silico screening is useful, it is essential to fully determine the biological activities of candidates by wet-lab validation studies.

Fibrocytes, which are bone marrow-derived collagen-producing cells, have been reported to be involved in pathogenesis of pulmonary fibrosis. Our previous study reported that tumor-infiltrating fibrocytes play a role in tumor progression and drug resistance in lung cancer. The present study therefore examined chemotactic factors for fibrocytes in tissues of non-small cell lung cancer (NSCLC) and their prognostic significance. Surgically resected tumor tissues were examined for the expression of chemotactic factors, including C-X-C motif chemokine 12 (CXCL12), CCL2, platelet-derived growth factor (PDGF)-AA and PDGF-BB, as well as tumor-infiltrating fibrocytes by immunostaining. The chemotactic ability of fibrocytes in response to each factor was evaluated using a migration assay by counting the migrated cells microscopically, and expression of receptors for chemotactic factors were analyzed by flow cytometry. The expression of CXCL12, but not CCL2, PDGF-AA, or PDGF-BB, was associated with the number of tumor-infiltrating fibrocytes in lung adenocarcinoma (LUAD), but not lung squamous cell carcinoma (LUSQ). In addition, patients with an increased expression of CXCL12 in LUAD but not LUSQ showed a significantly poorer prognosis compared with those with a decreased expression. However, the expression of CCL2, PDGF-AA and PDGF-BB was not correlated with the prognosis of patients with NSCLC. The number of fibrocytes was associated with a poor prognosis in LUAD. Fibrocytes derived from the peripheral blood of healthy subjects as well as patients with lung cancer expressed higher levels of CXCR4 compared with CCR2, PDGF and receptor-α and receptor-β. Overall, these results suggested that targeting tumor-infiltrating fibrocytes via the CXCL12/CXCR4 axis may be a useful strategy for controlling the progression of NSCLC, particularly LUAD.

A 62-year-old Japanese man presented a hard and painful intramuscular mass in the right upper arm during the chemotherapy for lung squamous cell carcinoma. Initially, this mass containing fluid accumulation was treated by radiotherapy and antibiotics as a muscle metastasis suspected to be complicated with local infection. However, because the swelling and pain of his right arm did not improve, he underwent a surgical debridement of the mass. These local treatments succeeded in relieving the patient's symptoms for a while. However, after temporary remission, the recurrence tumor developed the paralysis of right radial nerve and ulnar nerve in his upper arm. Despite further combined therapy including drainage, additional radiotherapy, and chemotherapy, paralysis made his performance status deteriorated. He was eventually discontinued aggressive treatment due to worsened general condition. We herein report a case of lung cancer followed unusual course due to muscle metastasis in the triceps muscle. Because the paralysis caused by muscle metastasis can be the factor to deteriorate the performance status of patient, the combined therapy including antibiotics, debridement, radiotherapy and chemotherapy as early as possible should be considered to avoid its risk.

Peritoneal disseminations from lung cancer are difficult to detect during the patient's clinical course. Therefore, complications of this condition are unclear. We report a case in which peritoneal dissemination from lung cancer complicated appendicitis. A 74‐year‐old man with lung cancer who was receiving maintenance therapy presented at our hospital because of abdominal pain. It was the seventh day after the 14th cycle of maintenance therapy with bevacizumab. He was diagnosed with acute appendicitis. The resected appendix showed acute appendicitis complicated by appendiceal metastasis from lung cancer. Adenocarcinoma was observed predominantly in the serous membrane from the neck to the tail of the appendix. The distribution of the adenocarcinoma was diffuse. Peritoneal dissemination was considered the route of metastasis. He was admitted to the palliative care unit 10 months after appendectomy. Appendiceal metastasis via peritoneal dissemination from lung cancer complicated appendicitis in our patient who had been receiving bevacizumab.