Fig 1.
αVβ3 integrin is selectively upregulated in the primary tumors of mice carrying neuroendocrine prostate cancer.
Immunostaining of the αVβ3 integrin (top panels), αVβ6 integrin (middle panels), and SYP (bottom panels) in prostate tumors from murine models with genetic knockdown of PTEN (SKO; n = 5), PTEN and RB1 (DKO; n = 5), and PTEN, RB1, and TRP53 (TKO; n = 5) in the prostatic epithelium. The bar at the bottom right corner of each panel represents 50 μm. First column: SKO; second column: DKO; third column: TKO.
Fig 2.
αVβ3 integrin is selectively upregulated in lung metastases of mice carrying neuroendocrine prostate cancer.
Immunostaining of the αVβ3 integrin (top panels), αVβ6 integrin (middle panels), and SYP (bottom panels) in the lung metastases from murine models with genetic knockdown of PTEN and RB1 (DKO; n = 5) and PTEN, RB1, and TRP53 (TKO; n = 5) in the prostatic epithelium. The bar at the bottom right corner of each panel represents 20 μm. First column: DKO; second column: TKO.
Table 1.
RNA sequencing analysis shows increased expression of ITGB3 mRNA in DKO and TKO tumors.
Fig 3.
Selective upregulation of αVβ3 integrin in the TRAMP (Transgenic Adenocarcinoma of the Mouse Prostate) mice.
IHC staining of αVβ3 (first row), αVβ6 (second row), and chromogranin A (CgA, third row) of prostate tumors from TRAMP mice (n = 24). Of the 24 samples analyzed, 13 show only a NE phenotype, 11 show only ADPrCa lesions, and 5 show both characteristics. IgG was used as negative control (last row). The bar at the bottom right corner of each panel represents 50 μm. Left column, ADPrCa; right column, NEPrCa.
Fig 4.
Increased expression of the αVβ3 integrin, but not αVβ6, correlates with the neuroendocrine marker SYP in LuCaP PDXs and human prostate tumor samples.
Immunohistochemical analysis of 42 LuCaP PDX models. (A) representative IHC staining for αVβ3 (left) or αVβ6 (right) integrin of SYP positive (top row) or SYP-negative (bottom row) LuCaP PDX models is shown. The bar at the bottom right corner of each panel represents 20 μm. (B) Heat map of the signature score for SYP, αVβ3 or αVβ6 integrin of each LuCaP is shown. Raw data are reported in the S1 Table. (C) Immunostaining analysis of αVβ3 and αVβ6 integrins and SYP primary tumors from ADPrCa patients. The bar at the bottom right corner of each panel represents 20 μm.
Fig 5.
Downregulation of androgen receptor does not increase αVβ3 or αVβ6 integrin expression.
Immunoblotting analysis of C4-2B and LNCaP cell lysates after AR downregulation by siRNA to AR. (A) Expression levels of αVβ3 integrin in C4-2B and LNCaP cells after AR downregulation. Immunoblotting was performed under reducing conditions. (B) Expression levels of αVβ6 integrin in C4-2B and LNCaP cells after AR downregulation. Immunoblotting was performed under non-reducing conditions. Actin or TSG101 serves as loading controls. NS, non-silencing.
Fig 6.
Schematic representation of the findings described in this study.
SKO (PB-Cre4 PTENloxP/loxP) cancer cells do not metastasize and express low levels of αVβ3 integrin and high levels of αVβ6 integrin. On the other hand, DKO and TKO tumors (PB-Cre4 PTENloxP/loxP RB1loxP/loxP and PB-Cre4 PTENloxP/loxP RB1loxP/loxP TRP53loxP/loxP respectively) express high levels of αVβ3 integrin and low levels of αVβ6 integrin. These αVβ3 positive tumors acquire metastatic behavior and expression of NE markers.