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Organic anion transporting polypeptide 1B3 (OATP1B3) is overexpressed in colorectal tumors and is a predictor of clinical outcome.

Lockhart AC, Harris E, Lafleur BJ, Merchant NB, Washington MK, Resnick MB, Yeatman TJ, Lee W - Clin Exp Gastroenterol (2008)

Bottom Line: OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as a multispecific transporter in the normal liver.We examined the expression and clinical significance of OATP1B3 in colon cancers in tissue microarrays.Within individual tumor grades, OATP1B3 expression was associated with improved 5-year survival, but not recurrence in patients with poorly differentiated tumors.

View Article: PubMed Central - PubMed

Affiliation: Vanderbilt University Medical Center, Nashville, TN, USA;

ABSTRACT

Background and aims: OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as a multispecific transporter in the normal liver. We examined the expression and clinical significance of OATP1B3 in colon cancers in tissue microarrays.

Methods: Immunohistochemistry was used to assess OATP1B3 protein expression in paraffinized colon tumor tissue microarrays. OATP1B3 immunostaining was evaluated by location and intensity. Relationships between OATP1B3 expression, known prognostic variables and clinical outcomes were examined.

Results: 278 colon tumor samples of all stages were evaluated for OATP1B3 expression. OATP1B3 immunostaining was detectable in the majority (56%) of the tumor samples. Higher OATP1B3 expression was seen in lower stage tumors (p = 0.003) and lower grade (p = 0.004) tumors, but was not predictive of 5-year survival or tumor recurrence as an independent variable. Within individual tumor grades, OATP1B3 expression was associated with improved 5-year survival, but not recurrence in patients with poorly differentiated tumors.

Conclusion: OATP1B3 expression was seen in the majority of colon tumors and may be a marker of lower grade and lower stage tumors and may predict for improved outcome in certain tumors.

No MeSH data available.


Related in: MedlinePlus

Immunohistochemical staining and immunoblotting for OATP1B3. A) Human liver section shows intense membraneous expression of OATP1B3. The specificity of OATP1B3 immunostaining was confirmed by negative staining with OATP1B3 antibody pre-incubated with the antigenic peptide. B) Normal colon tissue showing no detectable immunostaining, except in stromal inflammatory cells. C, D, and E) Colon tumor tissues showing negative C) and positive (moderate D) or high E)) OATP1B3 immunostaining. F) Immunoblotting for OATP1B3 showing OATP1B3 expression in three out of four paired colon tumor tissues, but not in normal tissues from the same donors.
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f1-ceg-1-001: Immunohistochemical staining and immunoblotting for OATP1B3. A) Human liver section shows intense membraneous expression of OATP1B3. The specificity of OATP1B3 immunostaining was confirmed by negative staining with OATP1B3 antibody pre-incubated with the antigenic peptide. B) Normal colon tissue showing no detectable immunostaining, except in stromal inflammatory cells. C, D, and E) Colon tumor tissues showing negative C) and positive (moderate D) or high E)) OATP1B3 immunostaining. F) Immunoblotting for OATP1B3 showing OATP1B3 expression in three out of four paired colon tumor tissues, but not in normal tissues from the same donors.

Mentions: OATP1B3 expression was determined by immunohistochemical (IHC) staining using a polyclonal OATP1B3 antiserum (raised against the C-terminal peptide sequence of OATP1B3 and previously verified for specificity).10 Because of the known expression of OATP1B3 in normal human hepatocytes,6 liver sections served as positive controls and were used to confirm the specificity of OATP1B3 antiserum by antigenic peptide blocking (Figure 1A). Tissue specimens were deparaffinized using EZ-Dewax (BioGenex, San Ramon, CA, USA), followed by antigen retrieval using citrate buffer (10 mM sodium citrate, 0.05% Tween 20, pH 6). Sections were incubated with a peroxidase blocking reagent to quench endogenous peroxidase activity. After incubation with blocking buffer for 1 hr, the slides were incubated with the rabbit polyclonal OATP1B3 antiserum (1:200) for 2 hours at room temperature. To avoid nonspecific avidin-biotin interactions, a commercially available blocking kit was used (Avidin Biotin Blocking kit, BioGenex). After washing, sections were incubated with biotinylated anti-rabbit IgG (BioGenex) for 20 min and then with streptavidin-HRP conjugate (BioGenex) for 20 min. After washes, the immune reaction was visualized using 3,3′-diaminobenzidine (DAB, BioGenex) and nuclei were counter-stained with hematoxylin. The specificity of immunoreactive signals was verified by omitting either primary or secondary antibody as well as by incubating with polyclonal OATP1B3 antiserum that has been neutralized by pre-incubation with the antigenic peptide at 37 °C for 2 hours.


Organic anion transporting polypeptide 1B3 (OATP1B3) is overexpressed in colorectal tumors and is a predictor of clinical outcome.

Lockhart AC, Harris E, Lafleur BJ, Merchant NB, Washington MK, Resnick MB, Yeatman TJ, Lee W - Clin Exp Gastroenterol (2008)

Immunohistochemical staining and immunoblotting for OATP1B3. A) Human liver section shows intense membraneous expression of OATP1B3. The specificity of OATP1B3 immunostaining was confirmed by negative staining with OATP1B3 antibody pre-incubated with the antigenic peptide. B) Normal colon tissue showing no detectable immunostaining, except in stromal inflammatory cells. C, D, and E) Colon tumor tissues showing negative C) and positive (moderate D) or high E)) OATP1B3 immunostaining. F) Immunoblotting for OATP1B3 showing OATP1B3 expression in three out of four paired colon tumor tissues, but not in normal tissues from the same donors.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3108628&req=5

f1-ceg-1-001: Immunohistochemical staining and immunoblotting for OATP1B3. A) Human liver section shows intense membraneous expression of OATP1B3. The specificity of OATP1B3 immunostaining was confirmed by negative staining with OATP1B3 antibody pre-incubated with the antigenic peptide. B) Normal colon tissue showing no detectable immunostaining, except in stromal inflammatory cells. C, D, and E) Colon tumor tissues showing negative C) and positive (moderate D) or high E)) OATP1B3 immunostaining. F) Immunoblotting for OATP1B3 showing OATP1B3 expression in three out of four paired colon tumor tissues, but not in normal tissues from the same donors.
Mentions: OATP1B3 expression was determined by immunohistochemical (IHC) staining using a polyclonal OATP1B3 antiserum (raised against the C-terminal peptide sequence of OATP1B3 and previously verified for specificity).10 Because of the known expression of OATP1B3 in normal human hepatocytes,6 liver sections served as positive controls and were used to confirm the specificity of OATP1B3 antiserum by antigenic peptide blocking (Figure 1A). Tissue specimens were deparaffinized using EZ-Dewax (BioGenex, San Ramon, CA, USA), followed by antigen retrieval using citrate buffer (10 mM sodium citrate, 0.05% Tween 20, pH 6). Sections were incubated with a peroxidase blocking reagent to quench endogenous peroxidase activity. After incubation with blocking buffer for 1 hr, the slides were incubated with the rabbit polyclonal OATP1B3 antiserum (1:200) for 2 hours at room temperature. To avoid nonspecific avidin-biotin interactions, a commercially available blocking kit was used (Avidin Biotin Blocking kit, BioGenex). After washing, sections were incubated with biotinylated anti-rabbit IgG (BioGenex) for 20 min and then with streptavidin-HRP conjugate (BioGenex) for 20 min. After washes, the immune reaction was visualized using 3,3′-diaminobenzidine (DAB, BioGenex) and nuclei were counter-stained with hematoxylin. The specificity of immunoreactive signals was verified by omitting either primary or secondary antibody as well as by incubating with polyclonal OATP1B3 antiserum that has been neutralized by pre-incubation with the antigenic peptide at 37 °C for 2 hours.

Bottom Line: OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as a multispecific transporter in the normal liver.We examined the expression and clinical significance of OATP1B3 in colon cancers in tissue microarrays.Within individual tumor grades, OATP1B3 expression was associated with improved 5-year survival, but not recurrence in patients with poorly differentiated tumors.

View Article: PubMed Central - PubMed

Affiliation: Vanderbilt University Medical Center, Nashville, TN, USA;

ABSTRACT

Background and aims: OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as a multispecific transporter in the normal liver. We examined the expression and clinical significance of OATP1B3 in colon cancers in tissue microarrays.

Methods: Immunohistochemistry was used to assess OATP1B3 protein expression in paraffinized colon tumor tissue microarrays. OATP1B3 immunostaining was evaluated by location and intensity. Relationships between OATP1B3 expression, known prognostic variables and clinical outcomes were examined.

Results: 278 colon tumor samples of all stages were evaluated for OATP1B3 expression. OATP1B3 immunostaining was detectable in the majority (56%) of the tumor samples. Higher OATP1B3 expression was seen in lower stage tumors (p = 0.003) and lower grade (p = 0.004) tumors, but was not predictive of 5-year survival or tumor recurrence as an independent variable. Within individual tumor grades, OATP1B3 expression was associated with improved 5-year survival, but not recurrence in patients with poorly differentiated tumors.

Conclusion: OATP1B3 expression was seen in the majority of colon tumors and may be a marker of lower grade and lower stage tumors and may predict for improved outcome in certain tumors.

No MeSH data available.


Related in: MedlinePlus