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Scientists from all over the globe are researching new ways to put an end to cancer. Some treatments have been successful, while others not so much. There are many types of cancer and many symptoms. Cancer is an abnormal growth of cells, which tend to proliferate in an uncontrolled way, in some cases, to metastasize. Cancer comes in many different forms. It is a group of more than one hundred different and distinctive diseases. Cancer is the Latin word meaning crab. In ancient times cancer was the word used for malignancy. The disease has a crab like tenacity, by which the malignant tumor grasps the tissue it invades much like a crab grasps its prey. Cancer is sometimes referred to as malignancy, a malignant tumor, or a neoplasm; which literally means new growth. Benign tumors, however, are NOT cancer. Cancer is not a contagious disease. One cannot acquire cancer by being sneezed on or breathed on. Cancer attacks any form of tissue and can have many different forms in each area it attacks. It is for that organ or tissue that is attacked which different types of cancer obtain its name. For example, cancer cells attacking the lung are named lung cancer, and so on and so forth. Any new tumor in the same area receives the same name as the original tumor. Some cancers are most common in both men and women. While others, like prostate cancer, are more likely to show up in men. Breast cancer is more common in women. Not all cancers are lethal and can even be cured most often, such as skin cancer. The leading cause of death from cancer in both men and women is lung cancer. Since there are many factors that cause the cancer cells to first attack the lung. However, scientist and doctors are always discovering cures and new research on cancer.
Recent studies have shown that the cancer stem cells (CSC) are highly resistant to chemo/radiation therapy. Cancer stem cells are generally dormant or slowly cycling tumor cells that have the ability to reconstitute tumors. Within many cancers however, the identities have not been defined nor existence has been known. A team of researchers led by Masaki Mori, at Osaka University, Japan, has now determined that amino peptidase (CD13) is a marker in human liver cancer cell lines and clinical samples. Liver cancer usually relapses along the fibrous capsule. The CD13+ cells survive after treatment and get enriched along the fibrous capsule. In cancer foci the CD13+ cells predominated in the G0 phase of the cell cycle and typically formed cellular clusters. Genotoxic chemo/radiation induces stress and the CD13 cells reduce the ROS induced DNA damage and protected these cells from apoptosis. A CD13 inhibitor combined with the chemotherapeutic agent 5-FU has shown to reduce tumor volume drastically when compared by either agent alone in mouse xenograft models. So by targeting CD13 and CSCs has lead the authors to believe that patients with liver cancer may very well be treatable in the near future.
CSCs are like normal tissue stem cells, which are capable of self-renewal and multi-differentiation. The CSCs have the ability to reconstitute tumors. CSCs are in the dormant or slow- growing phase of the cell cycle, much like the somatic tissue stem cells. This is the cause for metastasis, tumor relapse, and therapeutic refractor ness to chemo/radiation therapy. After the CSC of acute myeloid leukemia and chronic myeloid leukemia can also survive in a bone marrow niche, in the dormant G0 phase of the cell cycle. After a full liver transplant there are some cases where the dormant CSC cells have metastasized to the lung or bone. However, the cells in the liver are less dormant than the cells in breast cancer.
CSCs in dormant or slow growing phases are difficult to eliminate. Unlike the proliferating cancer cells that anticancer agents effect by dividing them. The most important research now being the identification of these CSCs, which are slow, growing or dormant. In order to determine these CSCs the distinct markers need to be established. In a previous study it is shown that the aims of the researchers are as follows: first, to take the candidate CSC markers and clarify the relationships reported between them. Second, determine whether these CSCs do in fact exist in liver cancer cells and to concentrate on cell-surface markers. Third, figure out why these dormant CSCs are resistant to the chemo/radiation. What characteristics make them protect these CSCs. Finally, after determining the above, targeting the CSCs and finding out a radical cure for the future. To determine all this, the researchers looked at and studied SP fractions. SP fractions express both hepatocyte and cholangiocyte markers. Much like the dormant CSCs and are highly resistant to anti-cancer agents, and high tumorigenicity in NOD/SCID mice.
It is the CD13 that correlates so closely to the SP cells. To further the research and find progress they selected 56 upregulated genes from a list of 268 genes upregulated in the SP cells. They then tested 47 commercially available antibodies on the 56 genes combined with the 43 markers reported to be closely associated with normal stem cells and CSCs. (J Clin Invest doi:10.1172/JCI42550. Aug 09 2010)
This, among others, is the ongoing research on the treatment for liver cancer. It is said that once the researchers isolate the cause for the dormant CSC the cure will not be too far away. They will figure out what is causing the cell proliferation and chemo/radiation resistance. Studies such as, cell fate tracing, sphere assay, immunohistochemistry, tumor cell preparation, inhibition of CD13, in vivo assay, and many others are being held to bring this treatment a step closer to positive results. There may be hope in the future for the liver cancer patients after all.