INI1 (SMARCB1) deletion of lung cancer: a case report and literature review

Abstract Background Integrase interaction factor 1 (INI1), also known as switch/sucrose non-fermentable (SWI/SNF)-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1), is a tumor suppressor gene. The INI1 protein is widely expressed in normal cell nuclei. This case report described a series of lung adenocarcinomas with deletion of the INI1 gene. Case presentation The patient, a 65-year-old female, underwent lung biopsy surgery at our hospital in April 2023. The tumor tissue was stained with immunohistochemistry and ultimately diagnosed as INI1-deficient lung adenocarcinoma. Lack of expression of the INI1 gene has been relatively rare in lung cancer. The INI1 (SMARCB1) protein is a subunit of the SWI/SNF chromatin remodeling complex. Undifferentiated cancers with missing SWI/SNF complexes have been demonstrated to be associated with poor sensitivity to traditional chemotherapy drugs and a poor prognosis. However, histone methyltransferase inhibitors may be effective in treating this tumor. Conclusions The purpose of our report was to enhance the understanding of this tumor among clinical and pathological doctors.