Our lab is interested in the signaling networks that operate in stem cell regulation during tissue homeostasis and regeneration, and in various diseases including cancers. We are particularly interested in signaling pathways that play important roles during embryonic patterning because these pathways have increasingly been recognized for their post-embryonic roles in the maintenance of tissue integrity and tumor initiation and growth, and seem to exert their post-embryonic effects through the regulation of tissue stem cell physiology. We address questions such as how stem cells mediate the repair of injured tissues, what is the role of developmental signaling pathways in stem cell-mediated tissue regeneration, and how dysregulation of these pathways and stem cell activity lead to the development of diseases including cancer.
Our laboratory currently focuses on three major areas: 1) Stem cell interaction with its microenvironment during tissue regeneration, cancer progression, and metastasis, with a particular emphasis on the Hedgehog signaling pathway (and other developmental pathways), 2) Novel strategy for regenerative medicine with a focus on in vivo tissue reprogramming and genome engineering, and 3) Personalized medicine to develop precise therapeutic intervention for individual cancer patients with genetic variability using 3-dimensional in vitro cancer model. To this end, we uses various in vitro/in vivo approaches including mouse genetics and stem cell organoid cutture.
1) Hedgehog signaling in stem cell interaction with microenvironment during tissue regeneration and in cancers Recent findings, including our studies of the bladder, and a survey of various epithelial tissues that we carried out suggest that, in many endoderm-derived epithelial tissues, Hh signaling acts in a non-cell autonomous way in which Hh response occurs only stromal cells to mediate epithelial and stromal interactions. The role of Hh signaling in various diseases of these tissues in the context of stem cell regulation, however, remains unclear. One focus of our current research is to understand how Hh signaling operates in regeneration and carcinogenesis of various endoderm-derived epithelial tissues in which Hh signaling operates in non-cell autonomous manner; Hh ligand is expressed in epithelial cells and Hh response is restricted to the stromal compartment.
Role of Hh pathway activity in bladder cancer metastasis. Our previous studies show that Shh expression is consistently lost during bladder tumor progression and that genetic ablation of Smo, a critical component of the Hh signal response, in Hh-responsive stromal cells significantly accelerates tumor progression. These studies strongly suggest that Hh signaling to stromal cells hinders formation of aggressive tumors. Using recently established mouse model of bladder cancer combined with genetic and pharmacological methods to manipulate the signaling pathways involving differentiative factors such as BMP4 and BMP5, we futher showed the role of these differentiative stromal factors in bladder cancer progression. We are currently investigating whether there is similar tumor-restraining effect of Hh signaling during bladder cancer metastasis. Effects of pathway manipulations on bladder cancer growth or metastasis would have obvious implications for the development of new therapeutic interventions in this malignant disease.
General role of the Hh signaling in the regeneration and carcinogenesis of endodermal organs. Our tissue survey of various endodermal organs shows that Hh response is restricted to the mesenchymal compartment of these organs. We hypothesize that regeneration and carcinogenesis of these tissues may depend on a reciprocal epithelial-mesenchymal interaction that may involve expression of Hh ligand in the epithelial stem cells and Hh response in stromal cells or the tumor microenvironment in a tumor setting. We are currently testing this hypothesis using tissue injury and cancer models that we have recently established of two different organs, the prostate and trachea: Post-pubertal prostate growth using castration and androgen replacement, ProbasinCre;PTEN flox model of prostate cancer, and tracheal epithelial regeneration upon airway injury using a toxic gas, sulfur dioxide. These injury models allow us to investigate the role of Hh signaling in stem cell regulation and the pathologies of those tissues, such as benign prostatic hyperplasia, prostate cancer, and various pulmonary diseases.
Development of genetic tools to investigate the role of Hh signaling in regeneration and diseases of various endodermal tissues. The tissue survey experiments show a similar pattern of Hh signaling between bladder and other endodermal tissues in which Hh response occurs in the mesenchymal tissue layer and Hh ligand is expressed in epithelial cells. Interestingly, however, we found that most endodermal tissues do not express Shh as a secreted molecule from epithelia as in the bladder. Instead, RT-PCR results show that Indian Hedgehog (Ihh), another member of the Hh family of secreted proteins, is expressed in most endodermal tissues including the prostate and trachea. In order to test the possibility that the expression of Ihh protein marks epithelial stem cells that can modulate homeostasis and regeneration of endodermal organs, and that this protein can elicit the Hh response in the surrounding microenvironment to regulate tissue response to injury and repair in vivo, it is necessary to develop new genetic tools to mark and manipulate Ihh-expressing cells. To this end, we are developinbg an Ihh knock-in mouse in which Cre recombinase fused with estrogen receptor (CreER) along with GFP (IRES-GFP) is targeted to the Ihh allele to control the expression of Cre and GFP in Ihh-expressing cells spatially and temporally. This new genetic tool in combination with other genetic methods will allow me to label Ihh-expressing cells and trace their lineage during regeneration of many endodermal tissues and to elucidate the role of Hh signaling in normal biology and pathology of these organs.
2) In vivo reprogramming coupled with genome editing technology to develop novel strategy for regenerative medicine The major goal of this research project is to develop an innovative strategy to overcome three major obstacles to current cell replacement therapies for a variety of disorders: 1) the shortage of specific cell types available from donors; 2) host immune rejection of cells from exogenous donors; and 3) safety concerns stemming from the in vitro culture of exogenous cells. We plan to genetically reprogram somatic cells directly into different lineages within endogenous tissues to restore the function of other damaged tissues.
For degenerative diseases caused by genetic mutations, it is important to correct the genetic defects prior to generation of new tissues by reprogramming because newly generated cells otherwise would be subject to degeneration due to the same genetic defects. Recent progress in genome engineering technology, such as the CRISPR-Cas9 system, allows for precise and efficient genome editing, suggesting the use of this approach as a therapeutic intervention for treating genetic disorders. By coupling this technology with in vivo reprogramming, the defective genes of precursor cells may be corrected prior to their reprogramming to generate functional cells. In this research project, we envision a new paradigm for regenerative medicine in which functional cells with corrected genetic defects are generated in the bladder to restore healthy and functional tissues.
3) Personalized medicine to develop individualized cancer therapy using 3-dimensional cancer model
Recent advances in early detection technologies and cancer genomics demand the development of personalized therapeutic interventions. Designing precise therapeutic strategies for individual patients with genetic variability at different cancer stages is required to prevent the potentially harmful effects of drugs developed from population-based research. To achieve this goal, it is imperative to develop in vitro cancer model systems that accurately recapitulate in vivo cancer progression, and that integrate the genomic profiles of individual cancer patients. These in vitro cancer model systems are also necessary to better understand the molecular and cellular basis of individual patients’ cancer pathogenesis. Although cell culture approaches have been utilized in pharmacological studies, cancer cell lines significantly underrepresent the genetic lesions of individual cancer patients due to a limited number of available cell lines. More importantly, cell culture approaches have been limited in their applications because they do not represent the full spectrum of in vivo disease progression. This research projects is designed to develop three-dimensional (3D) in vitro organoid systems that accurately model in vivo bladder cancer progression and to further establish human bladder tumor organoid lines that represent the pathology and molecular diversity of original tumors from individual patients.
Establishment of an in vitro cancer model system that recapitulates in vivo bladder cancer progression. We are currently establishing an in vitro bladder cancer model by coupling a 3D bladder organoid culture system to an advanced genome engineering technology based on the CRISPRCas9 system, followed by validation of that model. Previous studies have shown that combined inactivation of p53 and PTEN in the bladder epithelium is sufficient to induce invasive bladder cancer in vivo. Our preliminary data showed that urothelial stem cells with reduced expression of p53 and PTEN developed neoplastic organoids. By combining our bladder organoid culture with the CRISPR-Cas9 system, we are developing a 3D organoid culture system that mimics in vivo bladder cancer progression.
Establishment of patient-derived organoid lines from human bladder cancer patients. In vitro tumor models that integrate individual genomic profiles will be necessary to customize new drugs for the specific genetic contexts of individual patients. Although widely used in pharmacological studies, a 2D culture system with a limited number of available cell lines significantly underrepresents the genetic lesions of human bladder cancers. The goals of this project are to generate a large repertoire of patient-derived bladder cancer organoid lines, and to establish a human cancer model that recapitulates patient-specific cancer pathogenesis. We hypothesize that patient-derived bladder cancer organoids will accurately represent the pathology and the molecular diversity of individual patient tumors. Recent studies have shown that prostate cancer cells from biopsy specimens can be cultured and maintained using a 3D organoid system. We plan to generate a large repertoire of bladder tumor organoid lines from primary and metastatic bladder cancer cells using our recently developed tumor organoid culture methodology.
2007년 이후 대표논문
Lee JJ, Rothenberg ME, Seeley ES, Zimdahl B, Kawano S, Lu WJ, Shin K, Sakata-Kato T, Chen JK, Diehn M, Clarke MF, Beachy PA. (2016) Control of inflammation by stromal Hedgehog pathway activation restrains colitis. PNAS, 113(47):E7545-E7553
Shin K*, Lim A, Zhao C, Pan Y, Liao JC, Beachy PA*. (2014) Protective effect of stromal response to Hedgehog signaling in bladder cancer. Cancer Cell, 26:521-533. *Co-corresponding authors
Shin K*, Lim A, Odegaard JI, Honeycutt JD, Kawano S, Hsieh MH, Beachy PA*. (2014) Cellular Origin of Bladder Neoplasia and Tissue Dynamics of its Progression to Invasive Carcinoma. Nat. Cell Biol., 16(5):469-78. *Co-corresponding authors
Shin K*, Lee J, Guo N, Kim J, Lim A, Qu L, Mysorekar IU, Beachy PA*. (2011) Hedgehog/Wnt Feedback Supports Regenerative Proliferation of Bladder Stem Cell. Nature, 472(7341):110-4. *Co-corresponding authors
Oshima K, Shin K, Peng AW, Ricci AJ, Heller S. (2010) Mechanosensitive Hair Cell-Like Cells from Embryonic and Induced Pluripotent Stem Cells. Cell, 141(4):704-16
Shin K, Wang Q and Margolis B. (2007) PATJ Regulates Directional migration of Mammalian Epithelial Cells. EMBO Rep., 8(2):158-64