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The Role of KIF3B in Cancer Cell Migration and Metastasis
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- Author / Creator
- Raha, Srijan
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Metastasis is the leading cause of cancer-related deaths, yet there are no therapies that directly target this process. To identify potential therapeutic targets of metastatic dissemination, we recently completed the first whole human genome shRNA screen using a novel avian embryo intravital imaging platform developed by our group. Nine genes not previously linked to metastasis were identified, including KIF3B, which we determined is required for both in vivo cell migration and metastasis of human cancer cells in avian embryo and mouse models. KIF3B, a member of the kinesin family, is a (+)-end directed microtubule motor that targets the delivery of molecules from the cell interior to the cell periphery. Using an intravital imaging approach, we observed that cancer cells depleted of KIF3B form long cytoplasmic extensions but are unable to productively migrate. We hypothesized that this could be due to loss of key functions in focal adhesions and invadopodia, cellular structures that respectively link the actin cytoskeleton to the extracellular matrix and mediate matrix degradation through enrichment of MT1-MMP. Here we show that KIF3B knockdown by siRNA did not alter the size or number of focal adhesions and did not reduce invadopodia-mediated matrix degradation or extravasation. To increase depletion of KIF3B, we created KIF3B CRISPR knockouts and show that KIF3B is required for motility of human fibrosarcoma (HT1080) cells in vivo and is required for the trafficking of MT1-MMP to the cell surface where it is active. Therefore, the lack of a phenotype in our molecular mechanism experiments may have been due to low levels of KIF3B knockdown achieved with siRNA. Additionally, we show that targeting of KIF3B with custom-designed siRNA blocks human epidermoid carcinoma (HEp3) cell motility in vivo. Ultimately, continuation of this study may identify the molecular mechanisms of KIF3B in cancer cell migration and metastasis and lead to the development of specific anti-metastatic therapies.
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- Graduation date
- Fall 2017
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.