Project description:Colorectal cancer remains a major unmet medical need, prompting
large-scale genomics efforts in the field to identify molecular
drivers for which targeted therapies might be developed. We
previously reported the identification of recurrent translocations
in R-spondin proteins present in a subset of colorectal tumours.
Here we show that targeting RSPO3 in PTPRK-RSPO3-fusion positive
human tumour xenografts inhibits tumour growth and
promotes differentiation. Notably, genes expressed in the stem-cell
compartment of the intestine were among those most sensitive to
anti-RSPO3 treatment. This observation, combined with functional
assays, suggests that a stem-cell compartment drives PTPRK-RSPO3
colorectal tumour growth and indicates that the therapeutic
targeting of stem-cell properties within tumours may be a clinically
relevant approach for the treatment of colorectal tumors.
Project description:RSPO is a WNT pathway activator and functions as a potent regulator of stem cell growth in colon. RSPO family members were produced by several human tumors representing multiple tumor types including ovarian, pancreatic, colon, breast and lung cancer. Specific monoclonal antibody antagonists of RSPO family members were developed. In human patient-derived tumor xenograft models, anti-RSPO treatment markedly inhibited tumor growth either as single agents or in combination with chemotherapy. Furthermore, blockade of RSPO signaling reduced the tumorigenicity of cancer cells based on serial transplantation studies. In order to assess the impact of RSPO3 inhibition and gain insight in the anti-RSPO3 treatment mechanism of action, the global gene expression profiles of 4 human colorectal cancer patient derived models (PDX) were performed using Affymetrix microarray for the xenografts treated by the anti-RSPO3 antibody.
Project description:CT26 cells expressing lentiviral Cas9 and sgRNAs targeting either control or Gna13 were transplanted into immunocompetent BALB/c mice. Tumors were harvested and processed for RNA-seq
Project description:Defining the genetic drivers of cancer progression is key to understanding disease biology and developing effective targeted therapies. Chromosome rearrangements are a common feature of human malignancies, but whether they represent bona fide cancer drivers and therapeutically actionable targets, requires functional testing. Here, we describe the generation of transgenic, inducible CRISPR-based mouse systems to engineer and study recurrent colon cancer-associated EIF3E-RSPO2 and PTPRK-RSPO3 chromosome rearrangements in vivo. We show that both Rspo2 and Rspo3 fusion events are sufficient to initiate hyperplasia and tumor development in vivo, without additional cooperating genetic events. Rspo fusion tumors are entirely Wnt-dependent, as treatment with an inhibitor of Wnt secretion, LGK974, drives rapid tumor clearance from the intestinal mucosa without effects on normal intestinal crypts. Together, our study provides direct evidence that endogenous Rspo2 and Rspo3 chromosome rearrangements can initiate and maintain tumor development, and indicate a viable therapeutic window for LGK974 treatment of RSPO-fusion cancers.
