Prostate cancer invasion is influenced more by expression of a CD44 isoform including variant 9 than by Muc18

Abstract

The standard form of cell adhesion glycoprotein CD44 is a metastasis suppressor in prostate cancer. However, we previously showed by RT-PCR and Western blotting that cancer overexpresses unique CD44 variant v7-v10 isoforms. Muc18 is another cell adhesion marker reportedly overexpressed by prostate cancer. Matched frozen section-confirmed tumor and benign tissues were harvested from 10 prostatectomy specimens and tumor was microdissected from two lymph node metastases. Tissues were homogenized for RNA preparations, and RT-PCR was performed for the CD44v7-v10 sequence. In cultured prostate cancer cells, we caused RNA interference against CD44v9 and/or Muc18. We used PC3M cells and a derivative cell line called G s a, that constitutively expresses this G-protein and is more invasive. Lipofection was performed for a green fluorescent protein plasmid and for two 22-mer DNA fragments, cloned into a plasmid expression vector to generate hairpin, interfering dsRNA. Assays for invasion into Matrigel, a basement membrane matrix, were performed in 4-5 experiments. RT-PCR demonstrated expression of a 608 bp band representing CD44v7-v10 or a 638 bp band of Prostate cancer remains a public health problem of enormous magnitude; it is the second most common cause of cancer fatality among North American men and the most common in Great Britain. Only a minority of all cases invade locally and metastasize, thus requiring altered expression of cell adhesion molecules to allow tumor cell detachment, migration through a stromal matrix, and lymphovascular invasion.CD44, a family of transmembrane glycoproteins involved in homotypic cell, cell-matrix, and cellcytoskeletal interaction, holds promise as a prostate tumor marker. The extracellular domain of CD44 binds numerous matrix substituents: hyaluronic acid, heparin-affinity growth factors, vascular endothelial growth factor, p185 HER2 , epidermal growth factor, and hepatocyte growth factor. Its intracellular domain binds to ezrin, radixin, moesin and merlin, which interact with the cytoskeleton; notably, neutral endopeptidase 24.11 competes with CD44 for this interaction. 1 CD44 also binds directly to the cytoskeletal substituent ankyrin, thus determining cell and tissue architectural form. 2 CD44 is an oncodevelopmental protein, with roles in

Highly purified CD44+ prostate cancer cells from xenograft human tumors are enriched in tumorigenic and metastatic progenitor cells

“…This possibility certainly exists considering that CD44 has previously been implicated in facilitating PCa cell invasion in vitro (e.g. Lokeshwar et al, 1995;Draffin et al, 2004;Omara-Opyene et al, 2004). In this regard, it is of interest to note that the LAPC-9 tumors, which were initially isolated from a bony metastasis, contain many more CD44 þ cells than LAPC-4 tumors, which were originally isolated from a lymph node metastasis.…”

“…Furthermore, although CD44 expression is reported to be reduced in metastases (Nagabhushan et al, 1996;De Marzo et al, 1998;Noordzij et al, 1999), the CD44 þ PCa cells are found to predominate in two visceral metastases (Liu et al, 1999). Similar to expression studies, the potential role of CD44 in PCa development and metastases is controversial -although some studies show a tumor-suppressive function of CD44 in overexpression experiments (Gao et al, 1997(Gao et al, , 1998, many other studies implicate CD44 in PCa cell proliferation, adhesion, migration, and invasion in vitro as well as in metastatic dissemination in vivo (Lokeshwar et al, 1995;Paradis et al, 1998;Liu et al, 1999;Draffin et al, 2004;Omara-Opyene et al, 2004). Many studies mentioned above utilize either human tissues to carry out correlative immunohistochemistry (IHC) or bulk-cultured PCa cells to carry out overexpression experiments and the key experiment of using purified CD44 þ and CD44 À cells from the same culture or tumor to compare their potentially different biological and tumorigenic properties has not yet been done.…”

CD44 is a biomarker associated with human prostate cancer radiation sensitivity

“…The role of CD44s and CD44v in CaP development and progression is different, with studies showing both tumorinhibiting (CD44s) and tumor-promoting (CD44v) effects [13][14][15]. To date, no studies have investigated the correlation between CD44 expression and radiosensitivity of CaP.…”

Expression of CD44s in Incidental Prostate Cancer Is More Strongly Associated with Gleason Scores on Subsequent Radical Prostatectomies than Conventional Prognostic Parameters

“…Many cancer-associated genes such as CD44 are alternatively spliced [9] . Certain CD44 variants have been reported to have functional significance in prostate cancer [10] . Amongst these, the standard isoform CD44s has been extensively studied and its downregulation has been linked to high Gleason scores [5,11,12] .…”