DCLK1, a Putative Stem Cell Marker in Human Cholangiocarcinoma

Area of Science:

• Oncology
• Gastroenterology
• Cancer Stem Cell Biology

Background:

• Cholangiocarcinoma (CCA) is an aggressive cancer characterized by a high population of cancer stem cells (CSCs).
• Doublecortin-like kinase 1 (DCLK1) is recognized as a CSC marker in various gastrointestinal solid tumors.
• The role and expression of DCLK1 in intrahepatic CCA (iCCA) and perihilar CCA (pCCA) require further investigation.

Purpose of the Study:

• To evaluate the expression of DCLK1 in iCCA and pCCA.
• To investigate the biological function of DCLK1 in CCA.
• To assess the potential of DCLK1 as a therapeutic target and diagnostic biomarker for CCA.

Main Methods:

• Primary CCA cell cultures were established from surgically resected specimens and sorted for CSC markers (LGR5, CD90, EpCAM, CD133, CD13).
• DCLK1 expression was analyzed using real-time quantitative PCR, western blot, and immunofluorescence.
• Functional effects of a selective DCLK1 inhibitor (LRRK2-IN-1) were assessed on cell proliferation, apoptosis, and colony formation. DCLK1 was also analyzed in situ and in serum samples.

Main Results:

• Increased DCLK1 gene and protein expression was observed in LGR5+ pCCA and CD133+ iCCA cells compared to unsorted cells.
• LRRK2-IN-1 demonstrated a dose-dependent anti-proliferative effect, induced apoptosis, and reduced colony formation capacity and size in both iCCA and pCCA cell cultures.
• DCLK1 was detected in tumor tissues but not healthy tissue, and elevated serum DCLK1 levels were found in CCA patients compared to healthy controls and patients with HCC or cirrhosis.

Conclusions:

• DCLK1 identifies a specific CSC subpopulation in iCCA and pCCA, and its inhibition yields anti-neoplastic effects.
• DCLK1 inhibition presents a potential therapeutic strategy for CCA.
• Serum DCLK1 may serve as a valuable biomarker for early CCA diagnosis.