**4.8. Colon cancer**

16 Dehydrogenases

aggressive phenotype (Landen*, et al.*, 2010).

**4.5. Pancreatic cancer** 

**4.6. Prostate cancer** 

important cancers.

Hoogen*, et al.*, 2010).

**4.7. Brain cancer** 

chemotherapy in both *in vitro* and *in vivo* ovarian cancer models. They showed that ALDH1A1 expression and activity have increased chemo resistant ovarian cancer cell lines. Most importantly, down-regulation of ALDH1A1 expression has sensitized normally chemo resistant tumors to both docetaxel and cisplatin *in vitro* and in mouse models. Besides being a stem cell marker, ALDH1A1 is also a viable target for therapy and a mediator of the

Pancreatic adenocarcinoma is a highly lethal disease, which is usually diagnosed in an advanced state, and for which there is little or no effective therapies (Li*, et al.*, 2007)**.** Therefore, finding markers to detect a malignant cell transformation at an early stage is very important. Researches demonstrated that the pancreas possesses ALDH activity, and ALDH is also present in the pancreatic cancer cells. Different from other cancer tissues (such as ovarian and lung cancer), the activity of ALDH does not differ in pancreatic carcinoma tissue compared to normal pancreatic tissue. Additionally, serum levels of ALDH were not significantly elevated

in patients with pancreatic cancer in comparison to healthy controls (Jelski*, et al.*, 2011).

The latest estimates of global cancer incidence show that prostate cancer has become the third most common cancer in men, with half a million new cases each year, constituting almost 10% of all cancers in men (Quinn & Babb, 2002). Identifying the origin of cells in prostate cancer and its distant metastases may be important for the improvement of more effective treatment strategies and preventive therapies. Measurement of ALDH activity provides great contribution to functional identification and characterization of normal SCs and their malignant counterparts. ALDH activity is important for drug resistance, cell proliferation, differentiation, and response to oxidative stress of prostate cancer like other

ALDH enzyme activity is used for the isolation of "stem-like" cells based on a developmentally conserved stem/progenitor cell function. In a study, high ALDH activity was used to isolate human prostate cancer cells with significantly enhanced clonogenic and migratory properties both *in vitro* and *in vivo*. Similar to other cancer tissues, the percentage of ALDHhi cells in

Although high expression of ALDH7A1 is shown in prostate cancer cell lines, primary cultures, and in primary prostate cancer tissue and matched bone metastases, ALDH3A2 and ALDH18A1 are not observed high ALDH activity in human prostate cancer (van den

Glioblastoma (GBM) is the most common primary brain tumor in adults with an approximately 15-month survival (Stupp*, et al.*, 2005). Although there are several studies to

prostate cancer cell lines are also related to tumorigenicity and metastatic behavior.

Most colon cancers are adenocarcinomas that release mucus and other cellular secretions. In the United States in 2012, estimated new cases and deaths from colon and rectal cancer are reported as: 103,170 colon cancers and 51,690 deaths (Levin*, et al.*, 2008). Studies showed that ALDH1B1 and ALDH1A1 are differentially expressed in normal human tissues, but ALDH1B1 is expressed at higher levels than ALDH1A1 in human epithelial cancers. ALDH1B1 was abundantly expressed in adenocarcinomas originating from the tissue and particularly in colonic adenocarcinoma (Chen*, et al.*, 2011). Thus it can be deduced that ALDH1B1 may be a marker for colon cancer diagnosis.
