Sonic Hedgehog-dependent proliferation in a series of patients with colorectal cancer.
BACKGROUND
The Hedgehog (Hh) gene family is known to regulate development of stem cells. In addition, activation is responsible for the induction of GLI1 proto-oncogene and subsequent cellular proliferation. Sonic Hedgehog (SHh), one of the Hh family members promotes carcinogenesis in airway and pancreatic epithelia, is expressed in colonic stem cells. As differentiated colonic cells arise from constant renewal of Hedgehog-expressing colonic stem cells, SHh could be involved in human colonic carcinogenesis.


METHODS
Tissue samples of colorectal adenocarcinoma (T) and adjacent normal colon tissue (NT) were sampled from each of 44 consecutive patients with colorectal cancer. Specific transcription of SHh, GLI1, and the GLI1 downstream target FOXM1 were evaluated using semiquantitative reverse transcriptase polymerase chain reaction. Similar in vitro measurements of mRNA of GLI1 and FOXM1 transcription levels after specific induction by SHh-Np were performed in the HT-29 colorectal tumor cell line to confirm the in vivo results.


RESULTS
SHh mRNA was overexpressed in colorectal adenocarcinomas in 38 of 44 (86%) patients. Expression of transcription levels of GLI1 and FOXM1 correlated with SHh expression (SHh vs GLI1, r = 0.77, P < .0001; GLI1 vs FOXM1, r = 0.68, P < .0001; SHh vs FOXM1, r = 0.79, P < .0001). SHh overexpression did not appear to correlate with the patient characteristics evaluated. Similarly, when studied in the HT-29 colorectal cell line, exogenous SHh promoted cell proliferation, while inhibition of SHh expression decreased proliferation. Expression of GLI1 and FOXM1 mRNA increased with exogenous exposure to SHh.


CONCLUSIONS
We demonstrated increased expression of SHh mRNA in human colonic adenocarcinomas and in a colorectal cell line with downstream increased expression of GLI1 and FOXM1 mRNA known to promote cell proliferation. This upregulation within human colorectal adenocarcinoma tissue confirms the potential role of the Hh pathway in colorectal carcinogenesis and suggests a potential therapeutic target of Hh blockade in colorectal cancer.
Douard
Richard
R
General Surgery Department, APHP Georges Pompidou University Hospital, Paris. richard.douard@hop.egp.aphp.fr
Moutereau
Stéphane
S
Pernet
Pascal
P
Chimingqi
Mihelaiti
M
Allory
Yves
Y
Manivet
Philippe
P
Conti
Marc
M
Vaubourdolle
Michel
M
Cugnenc
Paul-Henri
PH
Loric
Sylvain
S
D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D000368:Aged; D002455:Cell Division / Q000502:physiology*; D045744:Cell Line, Tumor; D003106:Colon / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors / Q000235:genetics; D053823:Hedgehog Proteins; D006801:Humans; D009367:Neoplasm Staging; D015513:Oncogene Proteins / Q000235:genetics; D000090063:Proto-Oncogene Mas; D012004:Rectal Neoplasms / Q000235:genetics / Q000473:pathology*; D012811:Sigmoid Neoplasms / Q000235:genetics / Q000473:pathology*; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D000071676:Zinc Finger Protein GLI1
C107585:FOXM1 protein, human; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; D053823:Hedgehog Proteins; C000715470:MAS1 protein, human; D015513:Oncogene Proteins; D000090063:Proto-Oncogene Mas; C509239:SHH protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1