RASAL2 Confers Collateral MEK/EGFR Dependency in Chemoresistant Triple-Negative Breast Cancer.

Purpose: While chemotherapy remains the standard treatment for triple-negative breast cancer (TNBC), identifying and managing chemoresistant tumors has proven elusive. We sought to discover hallmarks and therapeutically actionable features of refractory TNBC through molecular analysis of primary chemoresistant TNBC specimens.

Experimental Design: We performed transcriptional profiling of tumors from a phase II clinical trial of platinum chemotherapy for advanced TNBC (TBCRC-009), revealing a gene expression signature that identified chemorefractory tumors.

Expressed Gene Fusions as Frequent Drivers of Poor Outcomes in Hormone Receptor-Positive Breast Cancer.

We sought to uncover genetic drivers of hormone receptor-positive (HR) breast cancer, using a targeted next-generation sequencing approach for detecting expressed gene rearrangements without prior knowledge of the fusion partners. We identified intergenic fusions involving driver genes, including , and , in 14% (24/173) of unselected patients with advanced HR breast cancer. FISH confirmed the corresponding chromosomal rearrangements in both primary and metastatic tumors.

Re-engineered p53 chimera with enhanced homo-oligomerization that maintains tumor suppressor activity.

The use of the tumor suppressor p53 for gene therapy of cancer is limited by the dominant negative inactivating effect of mutant endogenous p53 in cancer cells. We have shown previously that swapping the tetramerization domain (TD) of p53 with the coiled-coil (CC) from Bcr allows for our chimeric p53 (p53-CC) to evade hetero-oligomerization with endogenous mutant p53. This enhances the utility of this construct, p53-CC, for cancer gene therapy.

Delivery of a monomeric p53 subdomain with mitochondrial targeting signals from pro-apoptotic Bak or Bax.

Purpose: p53 targeted to the mitochondria is the fastest and most direct pathway for executing p53 death signaling. The purpose of this work was to determine if mitochondrial targeting signals (MTSs) from pro-apoptotic Bak and Bax are capable of targeting p53 to the mitochondria and inducing rapid apoptosis.

Methods: p53 and its DNA-binding domain (DBD) were fused to MTSs from Bak (p53-BakMTS, DBD-BakMTS) or Bax (p53-BaxMTS, DBD-BaxMTS).

The DNA binding domain of p53 is sufficient to trigger a potent apoptotic response at the mitochondria.

The tumor suppressor p53 is one of the most studied proteins in human cancer.1-3 While nuclear p53 has been utilized for cancer gene therapy, mitochondrial targeting of p53 has not been fully exploited to date.4,5 In response to cellular stress, p53 translocates to the mitochondria and directly interacts with Bcl-2 family proteins including antiapoptotic Bcl-XL and Bcl-2 and proapoptotic Bak and Bax.

A chimeric p53 evades mutant p53 transdominant inhibition in cancer cells.

Because of the dominant negative effect of mutant p53, there has been limited success with wild-type (wt) p53 cancer gene therapy. Therefore, an alternative oligomerization domain for p53 was investigated to enhance the utility of p53 for gene therapy. The tetramerization domain of p53 was substituted with the coiled-coil (CC) domain from Bcr (breakpoint cluster region).

Enhanced and selective killing of chronic myelogenous leukemia cells with an engineered BCR-ABL binding protein and imatinib.

The oncoprotein Bcr-Abl stimulates prosurvival pathways and suppresses apoptosis from its exclusively cytoplasmic locale, but when targeted to the mitochondrial compartment of leukemia cells, Bcr-Abl was potently cytotoxic. Therefore, we designed a protein construct to act as a mitochondrial chaperone to move Bcr-Abl to the mitochondria. The chaperone (i.

Direct induction of apoptosis using an optimal mitochondrially targeted p53.

Targeting the tumor suppressor p53 to the mitochondria triggers a rapid apoptotic response as efficiently as transcription-dependent p53. (1, 2) p53 forms a complex with the antiapoptotic Bcl-XL, which leads to Bak and Bax oligomerization resulting in apoptosis via mitochondrial outer membrane permeabilization. (3, 4) Although p53 performs its main role in the mitochondrial outer membrane, it also interacts with different proteins in the mitochondrial inner membrane and matrix.