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Comparative expression of the mitotic regulators SAK and PLK in colorectal cancer
J C Macmillan1, J W Hudson, S Bull
1Department of Surgery, Samuel Lunenfeld Research Institute and Mount Sinai Hospital, University of Toronto, Ontario, Canada.
Background:
Disruption of normal mechanisms for cell cycle regulation is important in carcinogenesis. SAK and PLK are members of the polo family of serine threonine kinases, which in lower organisms have been shown to be required for the precise regulation of mitosis. Studies of human polo family members have focused on PLK, which has been found to be overexpressed in several tumor types, with the degree of overexpression correlating with adverse clinical outcome. However, PLK expression had not previously been analyzed in colorectal cancer. SAK, a polo family member with unique properties, had not been systematically studied in any tumor type.
Methods:
In this study, SAK expression was evaluated in a series of sporadic human colorectal cancer specimens (n = 74) and compared with that of PLK. Expression was assessed by reverse transcription-polymerase chain reaction.
Results:
In the majority of cases, both SAK and PLK were more highly expressed in tumor tissue than in adjacent normal intestinal mucosa. Levels of SAK and PLK expression in tumor relative to paired normal mucosa correlated directly with patient age and with each other but did not correlate with tumor stage. These results suggest a mechanism for augmented disruption of mitotic regulation in older patients.
Conclusions:
The polo family mitotic regulators SAK and PLK are both aberrantly expressed in colorectal cancer. The potential prognostic significance of SAK and PLK expression in colorectal cancer will be evaluated in the future.
Insights
Aberrant expression of polo-like kinase (PLK) and SAK, key mitotic regulators, was observed in colorectal cancer. Higher expression in tumors correlated with patient age, suggesting a role in age-related mitotic disruption.
Area of Science:
- Cell Biology
- Molecular Oncology
- Cancer Research
Background:
- Cell cycle dysregulation is crucial in cancer development.
- Polo family kinases (SAK and PLK) are vital for accurate mitosis.
- PLK is overexpressed in various tumors, linked to poor outcomes, but not studied in colorectal cancer.
- SAK, a unique polo family member, lacked systematic tumor analysis.
Purpose of the Study:
- To investigate SAK and PLK expression in human colorectal cancer.
- To compare SAK and PLK expression levels in tumor versus normal tissue.
- To explore correlations between SAK/PLK expression and clinicopathological factors.
Main Methods:
- Evaluated SAK and PLK expression in 74 sporadic colorectal cancer specimens.
- Utilized reverse transcription-polymerase chain reaction (RT-PCR) for expression analysis.
- Compared tumor tissue expression with adjacent normal intestinal mucosa.
Main Results:
- Both SAK and PLK showed higher expression in colorectal tumors compared to normal mucosa.
- SAK and PLK expression levels correlated positively with patient age.
- Expression levels of SAK and PLK were also directly correlated with each other.
- No significant correlation was found between SAK/PLK expression and tumor stage.
Conclusions:
- SAK and PLK, polo family mitotic regulators, are aberrantly expressed in colorectal cancer.
- Aberrant expression suggests a role in colorectal carcinogenesis.
- Findings indicate potential age-related mechanisms in mitotic dysregulation.
- Future studies will assess the prognostic value of SAK and PLK in colorectal cancer.