Characterization of targets involved in chemotherapy resistance and tumor metabolism in lung cancer cells

Author(s)

Ana Paula Morelli

• Document type: Master's Dissertation
• Press: Limeira, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Aplicadas
• Defense date: 2022-06-21

Examining board members

Fernando Moreira Simabuco; Ana Paula Lepique; Carlos Kiyoshi Katashima

• Advisor: Fernando Moreira Simabuco

Abstract

Cancer is considered the leading cause of death worldwide and the one of biggest challenges of global public health. Lung cancer is the second leading cause of global cancer death, which is strongly associated with lately diagnosis and poor therapeutic efficacy. Surgery is the chosen treatment for patients in the stages I and II of NSCLC lung cancer and, in the infeasibility of surgical resection, the therapeutic strategies including chemotherapeutic agents as cisplatin and immunotherapy, like pembrolizumabe e avelumabe. Cisplatin it is one of the most effective antineoplastic drugs, althought it is strongly associated with innate and acquired resistance. It is known that some molecular characteristics, as increased and decreased expression of proteins, is associated with improvement or worsening of progression, treatment sensitiveness and disease outcome. In this work, using primarily a proteomic analysis, we identified important targets and pathways altered in resistant A549 lung adenocarcinoma cells. Among the targets that showed increased expression in the resistant condition, we chose to characterize STAT3 and PCNA. Although STAT3 has already been largely correlated with cisplatin resistance, little is described about PCNA, the relationship between both proteins and the relationship with mTOR pathway, important in the quemotherapeutic response. It is known that mTOR pathway it’s commonly active in cancer and this condition impact in cancer therapeutic outcome. Here we reported, combining different techniques such as CRISPR-mediated knockout, overexpression and functional assays, that partial PCNA loss of function and STAT3 ablation decreased clonogenic survival and sensitized A549 cells to cisplatin. Specifically for STAT3, ablation resulted in a decrease in the mesenchymal phenotype, observed by the clonogenic potential and by the expression of epithelial-mesenchymal transition markers. Furthermore, STAT3 knockout cells did not acquire cisplatin resistance-induced overactivation of the mTOR pathway and were more responsive to mTOR inhibition by rapamycin. That demonstrates that the combination of rapamycin and cisplatin is even more potent in the absence of STAT3. For PCNA, partial functional loss sensitizes to cisplatin while increasing expression of yH2AX, an important marker of DNA damage recognition. In addition, overexpression of PCNA increases STAT3 phosphorylation. Here we suggest that PCNA participates in cisplatin resistance both through its susceptibility to DNA damage via yH2AX and through its relationship with STAT3. Finally, we demonstrated that responsiveness to cisplatin may be dependent on crosstalk between STAT3, PCNA and mTOR, and synergistic inhibition of STAT3 and mTOR is possibly a potential approach against non-small cell lung cancer (AU)

• FAPESP's process: 19/00607-9 - Characterization of molecular targets involved in chemotherapeutic resistance and tumor metabolism of lung cancer cells
• Grantee: Ana Paula Morelli
• Support Opportunities: Scholarships in Brazil - Master