The impact of TP53 and PTEN tumor suppressor genes on response to different breast cancer treatment modalities

Abstract

Introduction. Breast cancer (BC) is the most frequent type of malignancy and the leading cause of cancer related death among women worldwide. BC is exceptionally heterogeneous disease and therefore distinct treatment modalities are necessary to address these differences. The aim of our study was to investigate the impact of TP53 and PTEN tumor suppressor genes (TSGs) inactivation on BC response to different treatment modalities and their possible cooperation, on post-operative BC samples. Methods. Patients were classified, based on applied adjuvant therapy, into four distinct groups: those that received hormonal therapy (HT) only, hormonal therapy combined with chemotherapy (HT/CHT), hormonal therapy combined with chemo and biological therapy (HT/CHT/H), and other systemic therapies that exclude HT. Functional inactivation of TP53 and PTEN TSG’s were studied by mutation, loss of heterozygosity (LOH) and hypermethylation analysis. Results. Our results revealed that TP53 gene was altered in 63 out of 90 specimens (70%), while the frequency of PTEN alterations was slightly lower, 54 out of 90 (60%). Simultaneous inactivation was detected in 43 tested samples (48%) with significant association between two analyzed TSGs. Further, we found that TP53 status has significant influence on patients’ therapy response. Contrary to this, no significance was found between mutational status of PTEN and various treatment modalities. However, significant association was found between the type of applied therapy and simultaneous alterations of these two TSGs (p = 0.00001). Conclusion. Patients with wtTP53 show significantly better therapy response regardless of the type of therapy, compared to carriers of altered TPp53 gene.

Uvod. Rak dojke (RD) je najčešći tip maligniteta i vodeći uzrok smrti od raka kod žena širom sveta. RD je izuzetno heterogena bolest i stoga su neophodni različiti modaliteti lečenja da bi se pokrile ove razlike. Cilj našeg istraživanja je bio da se ispita uticaj inaktivacije TP53 i PTEN tumor supresorskih gena (TSG) na odgovor RD na različite modalitete lečenja, kao i njihova moguća saradnja u tome, na postoperativnim uzorcima RD. Metode. Pacijentkinje su klasifikovane, na osnovu primenjene adjuvantne terapije, u četiri različite grupe: one koje su primale samo hormonsku terapiju (HT), hormonsku terapiju u kombinaciji sa hemoterapijom (HT/CHT), hormonsku terapiju u kombinaciji sa hemoterapijom i biološkom terapijom (HT/CHT/H) i druge sistemske terapije koje isključuju HT. Funkcionalna inaktivacija TP53 i PTEN TSG je proučavana analizom mutacionog statusa, gubitka heterozigotnosti (LOH) i metilacionog statusa. Rezultati. Naši rezultati su pokazali da je TP53 gen izmenjen kod 63 od 90 pacijenata (70%), dok je učestalost promena PTEN gena bila nešto niža, 54 od 90 (60%). Simultana inaktivacija je detektovana u 43 testirana uzorka (48%) sa značajnom povezanošću između dva analizirana TSG-a. Dalje, pokazali smo da status TP53 ima značajan uticaj na odgovor pacijenata na terapiju. Suprotno ovome, nismo pokazali značajnu asocijaciju između mutacionog statusa PTEN-a i različitih modaliteta lečenja. Međutim, utvrđena je značajna povezanost između primenjenih terapija i simultanih inaktivacija ova dva TSG-a (p = 0,00001). Zaključak. Pacijenti sa wtTP53 pokazuju značajno bolji terapijski odgovor bez obzira na vrstu terapije u poređenju sa nosiocima mutiranog TP53 gena.