Effect of SARS-CoV-2 infection on breast cancer cell lines (7days)

COVID-19 pandemic, caused by SARS-CoV-2 virus, had significant consequences for individuals already dealing with various pathological conditions, including breast cancer. Emerging evidence suggests that SARS-CoV-2 infection may directly affect breast cancer cell biology, even though a deeper understanding of the virus's effects on tumor cells is still not completely achieved. The present study aimed at examining the molecular events taking place in three different breast cancer cell lines of distinct molecular subtypes upon SARS-CoV-2 virus infection. Specifically, MCF7, MDAMB231, and HCC1937 cell lines, representing luminal A, basal B/claudin low, and basal A molecular subtypes, respectively, were subjected to SARS-CoV-2 infection and gene expression profile analysis was conducted at 24 hours and 7 days post infection. Obtained data revealed that MCF7 cells exhibited the highest susceptibility to viral replication. Interestingly, genes upregulated by SARS-CoV-2 virus in all three cell lines were able to identify a subgroup of breast cancer patients characterized by poor prognosis. Given the ongoing spread of the SARS-CoV-2 virus within the population, it is crucial to gain a better comprehension of its direct impact on breast cancer and to assess the long-term consequences of COVID-19 on breast cancer outcomes. MCF7, MDAMB231 and HCC1937 cell lines were seeded at a density of 700000 cell/well in a 6-well culture plate in quadruplicates in complete RPMI 1640 medium at 37°C, in a humidified atmosphere containing 5% CO2. The following day, cells were infected with SARS-CoV-2, lineage B.1 (SARS-CoV-2/human/ITA/Milan-UNIMI-1/2020, GenBank MT748758.1). Cell infection was carried out by viral adsorption in complete medium for 2 hours, using a multiplicity of infection (MOI) of 0.1 (8.78x108 copies/mL) at 37°C in a 5% CO2 atmosphere. All studies with SARS-CoV-2 were performed in a Biosafety Level 3 laboratory. Total RNA was extracted 24 hours and 7 days post infection with QIAzol Lysis Reagent (Qiagen, Hilden, Germany) and RNeasy Mini Kit (Qiagen, Hilden, Germany) according to manufacturer’s instructions.