01. Gene therapy Boulikas.pdf - Gene therapy & Molecular Biology

hematopoietic cells against
antifolates and P-glycoprotein
effluxed drugs. Hum Gene Ther 8,
1773-1783. Reproduced with kind
permission from the authors and
Mary Ann Liebert, Inc.
cDNA. Similar protocols (#43, 44, 59, 89) use CD34 +
autologous bone marrow cells retrovirally-transduced with
MDR1 cDNA for hemoprotection of patients treated for
ovarian, brain, or breast cancers (Appendix 1).
XXV. Antisense gene therapy of cancer.
Among a variety of approaches to gene therapy of cancer,
antisense oncogene gene therapy is a strategy aiming at
correcting genetic disorders of cancer through correction
of the abnormal expression of oncogenes implicated in
signal transduction and control of proliferation. A number
of protocols have been approved using antisense gene or
oligonucleotide delivery. Protocol 29 uses a combination
of p53 cDNA and K-ras antisense for non-small cell lung
cancer. Protocol 41 uses antisense Rev for AIDS, protocol
91 antisense RRE decoy gene and protocol 168 uses
antisense TAR and transdominant Rev protein genes for
HIV infections. Protocol 64 uses antisense c-fos or
antisense c-myc for breast cancer. Protocol 82 uses
intraprostate injection of antisense c-myc for advanced
prostate cancer. Protocol 162 uses TGF-ß2 antisense genemodified
autologous tumor cells for malignant glioma.
And, protocol 189 uses antisense Insulin-like Growth
Factor I for glioblastoma (see below).
A. Antisense c-fos and c-myc
Because c-fos proto-oncogene has been implicated as a
regulator of estrogen-mediated cell proliferation, antisense
c-fos has been used to cause an inhibition of s.c. tumor
growth and invasiveness of cells the growth of which
depends on estrogen. Ex vivo transduction of MCF-7
human breast cancer cells with antisense c-fos, regulated
by mouse mammary tumor virus control elements and
delivered by a retroviral vector, produced expression of
anti-fos RNA, decreased expression of the c-fos target
mRNA, induced differentiation, and inhibited s.c. tumor
growth and invasiveness in breast cancer xenografts in
nude mice; a single injection of anti-fos inhibited i.p.
MCF-7 tumor growth in athymic mice with a
corresponding inhibition of c-fos and TGF-β1 (Arteaga
and Holt, 1996). A phase I clinical study for the treatment
of metastatic breast cancer uses in vivo infection with
breast-targeted retroviral vectors expressing antisense c-
Boulikas: An overview on gene therapy
80
fos or antisense c-myc RNA (Holt et al, 1996; protocol
#64, Appendix 1, page 163).
B. Antisense insulin-like growth factors I
and II and their receptors
Insulin-like growth factors I and II (IGF-I and -II) are
expressed preferentially in bone tissue and contribute to
bone metastases of cancer cells expressing IGF receptors.
Prostate cancer cells express IGF-I receptor; this favors
metastasis to bone, the most frequent tissue for prostate
metastasis. An antisense IGF-IR construct, under control
of the ZnSO4-inducible metallothionein-1 promoter, was
engineered by reverse transcription-PCR on total RNA
with primers specific for the 0.7 kb cDNA of IGF-IR and
subcloned into episomal vectors in the antisense
orientation. Transfection of the construct into prostate
cancer PA-III cells in culture was able to reduce
dramatically the expression of IGF-IR after induction of
the cells with ZnSO4 (Burfeind et al, 1996). This
inhibition resulted in reduction in expression of both uPA
and tPA; whereas PA-III cells were able to induce large
tumors in nude mice, PA-III cells transfected with the
antisense vector either developed tumors 90% smaller or
remained tumor -free for long times postinjection
(Burfeind et al, 1996).
Lafarge-Frayssinet et al (1997) have developed a
strategy for inducing a protective immunity by tumor cells
transfected by the IGF-I antisense vector: the
hepatocarcinoma cell line LFCI2-A, expressing both IGF I
and II, produces voluminous tumors when injected
subcutaneously into syngeneic rats; when LFCI2-A cells
were transfected with an episomal vector expressing IGF-I
antisense RNA, the cells became poorly tumorigenic
exhibited a 4-fold increase of the MHC class I antigen,
and, when injected subcutaneously, inhibited the growth
of the parental tumoral cells or induced regression of
established tumors; this loss of tumorigenicity and
protective immunity was not observed after transfection
with the IGF-II antisense vector (Lafarge-Frayssinet et al,
1997). Cationic lipid-mediated transfer of antisense cDNA
for IGF I is in clinical trial for glioblastomas (protocol
#189 in Table 4 in Martin and Boulikas, 1998, this
volume, page 203).