Patient-derived breast tumor organoids: genomic and functional studies for the characterization of triple negative breast cancer

Our laboratory aims at generating organoids from freshly resected breast tumors. High-throughput sequencing and comprehesive genomic analysis will be performed on these patient-derived organoids to identify novel genes and pathways perturbed by genetic alterations in triple negative breast cancer (TNBC). We will also use these tumor organoids to study patient-specific differences in pathway dependency, and screen compounds to identify personalized therapy strategies.

Resistance mechanisms to targeted therapies in breast cancer

Recent clinical studies provide promising data that kinase inhibitor therapies have led to remarkable initial tumor responses in a variety of cancers. However, the tumor shrinkage is usually incomplete, and majority of patients inevitably relapse with tumor resistant to the inhibitor. PI3K/Akt pathway is one of the most frequently deregulated signaling cascades in epithelial cancers, and a number of small molecule inhibitors targeting this pathway are entering the clinic. However, little is known about the adaptive signaling and genetic events that underling PI3K/Akt inhibitor resistance. To investigate mechanisms of acquired resistance in breast cancer extensively, we use genetically defined tumor lines to model resistance emergence in vitro and in vivo. We are also collaborating with clinical teams to study resistance development in tumor biopsies of breast cancer patients. In addition, the recent advances in CRISPR technology will allow us to do systematic screens for the functional characterization of critical genes in resistance. These complementary approaches will provide insights for designing new mechanism-based inhibitors and combination strategies to circumvent resistance.

3D culture for uncovering Akt isoform-specific signaling in multiple cancer contexts

The three isoforms of Akt (Akt1-3) were originally thought to function redundantly in pathophysiology. It is now clear that they have specific signaling roles in modulating phenotypes associated with malignancy. We and others have previously demonstrated opposing functions of Akt1 and Akt2 in regulating breast cancer cell motility and metastasis. More recently, we have revealed a distinct role of Akt2 in PTEN-deficient tumor maintenance. Our laboratory is interested in identifying distinct functions of Akt isoforms in different aggressive solid tumors, and defining the mechanistic basis. The major approach we are using is modulation of gene function in a temporally controlled manner in 3-dimensional culture system. The 3D system is employed to better recapitulate the microenvironment and morphology of tumors growing in vivo. We have found distinct functions of Akt isoforms in prostate, lung and ovarian cancer progression. Currently, we are dissecting the molecular mechanisms by which Akt isoforms regulate apoptosis, polarization and invasion, key events in cancer initiation and progression. We are using live cell imaging to examine the intracellular dynamics in a real-time manner.

Identification of Akt targets that regulate cancer growth, survival and metastasis

In addition to the opposing roles of Akt1 and Akt2 in breast cancer metastasis, we have recently identified an isoform-specific role of Akt3 in regulating TNBC growth and therapeutic resistance. These findings point to Akt3 and its downstream substrates as novel targets for breast cancer therapy. We have developed a genome-wide, mass spectrometry-based proteomic strategy to identify novel Akt isoform-specific targets. Combining with RNAi and bioinformatics approaches, substrates discovered in the screens are used to delineate isoform-specific signaling networks that drive cancerous growth and metastasis. The goal of these studies is to identify novel biomarkers and targets for therapeutic interventions in different subtypes of breast cancer.