Role of human papillomavirus type 18
subgroup of prostatic cancer|
with bone metastases: Its protein E2
contains the osteoprotegerin active site.
Mong Ky (1,
Adrien (3, 5),
University Paris-Sud XI ; correspondence: 31 Av du Bois,
Châtenay-Malabry, France. E-mail :
2 Therapeutic Chemistry, Faculty Pharmacy, University
Paris-Sud XI, Châtenay-Malabry. E-mail :
3 University 7-Denis Diderot, CNRS Tour 33/34 ESA7057, 2
Place Jussieu, Paris Cedex 05. E-mail :
4 Centre Médical Europe, 44 rue d'Amsterdam, Paris.
E-mail : email@example.com.
5 Association Positifs, BP 230 75865 Paris Cedex 18. E-mail
In Japan, the
oncogenic human papillomavirus (HPV) type 18 is found by
polymerase chain reaction (PCR) in 80% (12/15 cases) prostatic cancer
(PC) with bone metastases versus 0% in
controls (Anwar K,
1992) . The
oncogenic HPV-18,-16,-33 are frequent in a PC subgroup in
Germany [HPV-16 in 10/47(21%)] (Serth J, 1999), Canada [13/27 (48.1%)] (McNicolP.J., 1991), Japan (41%) (Anwar K, 1992), in Michigan (USA)
[3/23(13%)] (Sarkar F.H., 1996), Italy [6/8(75%)] (Rotola A., 1992) and in Montpellier, France (HPV-16
in 53%) (Moyret-Lalle C.,
1995). In Sweden,
high antibody levels against HPV-33 multiplied the risk by
2,3 fold (Adami
H.O., 2003). In
Finnish men, in a prospective study, the presence of
antibodies against HPV-16 was associated with an odds ratio
(OR) of 2.58 and antibodies against HPV-18 with a
statistically significant odds ratio of 2,88 (Dillner J., 1998). Hisada M. (2000) found also an OR of 2.7 for HPV-16
antibodies in a prospective cohort study.
Numerous negative results
have been reported, and this very important point was
analyzed in detail (for tables, see: Terris M.K., 1997 and Strickler H.D.,
Discrepancies are explained in DISCUSSION below : All
positive PCR studies (80%, 75%, 53%, 48.1%, 41%, 21%) have
used HPV E6 as primers set, and
tissues (except Anwar K, who used archival tissue) ; whereas
negative (0%) and weak results employed HPV consensus
L1 and archival formalin-fixed,
paraffin-embedded tissues . In seroepidemiological studies,
the prospective cohort studies were positive whereas the
retrospective case-control studies generally
The very low concordance
of PC in homozygotic twins, (where concordance was observed
only 16 times, whereas discordance is 135
times) (Morganti G,
strongly favoured an environnemental factor : Viral
(papillomavirus, polyomavirus) or toxic (cadmium, tobacco). Epidemiology
1997) speaks for a
sexual transmission [militaries, multipartenarism, herpes
virus type 2 infection (Haid M., 1984), prostitutes frequentation , non
use of condoms, gonorrhea, syphilis (Hayes R.B., 2000), marriage, wife with uterus
cervical cancer, transmitting her HPV to the
BETWEEN HPV MOLECULAR BIOLOGY AND PROSTATIC CANCER.
There are many connections
between HPV and PC : The HPV oncogènes E6 and E7 are
inhibiting the tumor suppressors p53 and pRb, precisely
those altered in PC (Sellers W.R.,
HPV is integrating
upstream of Myc oncogene, which is amplified in 47% of
metastatic PC (Kaltz-Wittmer C.,
2001). There is a
loss of heterozygoty of Bin-1, an anti-myc tumor suppressor,
in about half of PC
(Sakamuro D., 1996).
We found an Epidermal
Growth Factor (EGF) motif in HPV E2 (Tran M.K.G., 1993) and EGF receptor ,which gene is on
chromosome 7p, is overexpressed in 33.6% of PC
1998) ; and
Trisomy 7 is correlated with a bad prognosis of PC
1994). There is a
" cross-talk " phenomenom between EGF and androgen receptor,
that can be activated in the absence of the
ligand (Cullig Z.,
1997 ; Hobisch A., 1997). EGF transduction pathway is
signalling by Ras, which is frequently mutated in PC
1992). HPV-16 E5
(Pim D., 1992).
As we have
found a molecular mimicry between breast cancer virus 3'ORF
and PTHrP (parathormone-related peptide) which could explain
bone metastasis in breast cancer (Tran M.K.G., 2003), similarly we tried to elucidate
the HPV-18 role in bone metastases, as HPV-18 was so
strongly (80% PC versus 0% controls) (Anwar K, 1992) and specifically associated with
the presence of bone metastasis. HPV-18 is known to induce a
severe, aggressive cervical cancer in women. HPV-18 has been
found also in a metastatic lymph node , and in a
seroepidemiological study the OR is 2.88 when antibodies
against HPV-18 are present (Dillner J, 1998). To find a molecular biology
explanation would strengthen the role of HPV-18 in the
occurrence of a subset of particularly aggressive and lethal
PC, that resist to hormonal treatment.
aminoacids (AA) sequences between HPV-18 E2 protein and 3
proteins of calcic homeostasis : Osteoprotegerin (OPG), PTH
(parathyroid hormone) and PTHrP (PTH-related protein). The
screening sequence is the tetrapeptide HQLL common to
osteoprotegerin and PTHrP.
Osteoprotegerin is the most
homologous to HPV-18 E2, spanning 8 aminoacids, which is
significant . A contrario, histidine (His) is absent in
Owing to the
low HPV copy number in prostatic tissue (Serth J., 1999), the PCR seemed the most
appropriate method to reveal HPV in prostatic cancer. But
the choice of the primer sets is crucial and can alone determine
the PCR positivity (Terris M.K., 1997) : In the same patient, E6 primer
set obtained 11/53 (20.8%), compared to 0/53 (0%) for L1
Previous numerous negative
results have been reported, throwing doubt, and this very
important point was analyzed in detail (for review tables,
see: Terris M.K.,
1998) : We can now
clarify further the debate and try to explain some of these
apparent discrepancies, on the basis of 2 criteria (first,
the primer sets used, second, the prostatic tissue
preparation) as well as the PC heterogeneity.
RESULTS: All positive PCR studies (80%,
75%, 53%, 48.1%, 41%, 21%) have used HPV E6 as primers set, and
tissues (except Anwar K, who used paraffin tissue and E6
primer; like Sarkar who obtained only 13%) .
RESULTS: Whereas almost all negative (0%)
and weak (about 15%) results employed HPV
formalin-fixed, paraffin-embedded tissues ; these "
L1-paraffin " authors were numerous : Serfling U (0%), Effert P.J. (0%), Terris M.K. (0%) Tu H. (2.3%), Ibrahim G.K. (16%), Suzuki H. (16%), Widerhoff L. (12.5%) (15.2% in whites).
L. is the only
author to obtain no result with E6 primers set, like
(1998) [0/38 (0%)]
in paraffin tissue. It seems that paraffin is not
recommanded for HPV research, because the majority of
results are negative or very weak. Iwasawa A (1990) and Gherdovich S (1997) have negative results, but their
patient number is statistically too low (n=5 only).
negative results but used in situ hybridization instead of
PCR. There is some doubt on the results of Strickler H.D.,
1998, who found
zero HPV everywhere (cancer and adenoma controls) : There is
no explanation for their failure (they correctly used E6 and
frozen tissue for PCR), except the PC heterogeneity (they
may have examined other PC subsets linked to cadmium,
polyomavirus and genetics). It is unknown why
H.D. did not use
the same E6 primers set than for example
Anwar. A slightly different sequence may
be crucial for perturbing the results.
For the discrepancies in
seroepidemiological studies, which are less convincing than
PCR studies, the criteria used for discussion is whether
they were prospective or retrospective (retrospective is
more subject to errors, because the choice of controls can
always be debated) : The prospective cohort studies were positive
(Hisado M., 2000 ;
Dillner J. 1998),
whereas the retrospective case-control studies generally
H.D., 1998 ; Rosenblatt K.A., 2003 ; HayesR.B.,2000 ; Adami
However, Adami H.O.
results with HPV-16 and -18, but positive result with
HPV-33 (OR = 2.3).
All these HPV positive
results are concerning a subset of PC (about 30-40%), but it
must be kept in mind that non-HPV linked PC exist, for
example PC related to tobacco, cadmium (toxic) or
polyomavirus (viral) (Zambrano A., 2002)
or genetic. So a
large PC heterogeneity can also explain as well negative
1998) or weak
subgroup with bone metastases in Japan is linked by PCR in
80% cases to HPV-18, versus 0% in controls. HPV-18 E2
protein contains an OPG motif. This confirms the viral
etiology of a PC subgroup, and explains the mechanism of
formation. Cidofovir (Vestide ®) is an active anti-viral
against HPV (De
Clerq E., 2003)
and is also used as a 1% gel in cervix intraepithelial
neoplasia grade III (Snoeck R., 2000). Imiquimod, a imidazoquinoline immune system
stimulator, has been approved for the therapy of genital
S.M., 2003). An
against cervical cancer in a clinical trial (Koutsky L.A.,
2002). If a subset
of PC has to be considered as a sexually transmitted
disease, it would
theorically follow the same rules as for every STD, i.e.
obligatory declaration, systematic viral (HPV, polyomavirus)
research in the partner and simultaneous treatment of the
partner to avoid any ping pong reinfestation. Obviously,
none of these sanitary measures is effectively entered in
routine today. There is also a need to develop good and
fiable serological tests, alike those used in women cervical
cancer (virus-like particles or VLPs) in a cohort
prospective seroepidemiological study, and respect the
conditions of a highly sensitive nested PCR with specific E6
(not L1) primers set (Terris M.K.,1997 ; Anwar K,
1992) on fresh
frozen (not paraffin-embedded archival) prostatic tissue,
without forgetting to research associated polyomavirus
spectrum of oncogenic HPV types being the most exhaustive as
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