The current study
showed that hPAF1C expression is a prognostic biomarker for early
stage lung cancer. NSCLC patients with low hPAF1C expression
levels showed significantly better overall survival (Fig. 1). To our
knowledge, this study is the first one to describe the role of hPAF1C
in NSCLC prognosis.
The oncogene MYC family members encode phosphoproteins
involved in cell growth and its dysregulation is linked to tumorigenesis.
The MYC family includes N-MYC, C-MYC and L-MYC proteins,
which all have a Helix-loop-Helix motif, and act as
transcription factors. MYC proteins are normally involved in cell
proliferation by regulating the expression of various regulators of
the cell cycle [1]. The amplification of MYC genes have been
demonstrated in tumor samples or cancer cell lines of several
cancers, which including lung cancer [8,9]. In this report, the
expression of hPAF1 was examined to be positively correlated with
c-MYC in tumor samples of NSCLC patients and in several NSCLC
cell lines (Fig. 2), providing an interesting link for hPAF1C in the
pathology of NSCLC.
Indeed, the endogenous hPAF1C was found to be required for
the expression of c-MYC in NSCLC cells both in western blot and a
reporter assay (Fig. 3), indicating that hPAF1C is involved in the
transcriptional regulation of c-MYC expression. Furthermore,
several NSCLC cell lines were showed to be dependent on hPAF1C
for their proliferation and clongenic survival. More interestingly,
when both hPAF1C and c-MYC expressions were co-depleted by
siRNAs, the proliferation of H838 NSCLC cells was completely
inhibited, and the effect was much stronger than either single
depletion (Fig. 4). Above results highlight the possible mechanism
that hPAF1C promotes lung tumorigenesis synergistically with c-
MYC oncogene.
In conclusion, we demonstrated that hPAF1C is a novel prognostic
factor in early-stage NSCLC, with a positive correlation with
c-MYC expression. The hPAF1C expression has a strong impact in
NSCLC cell growth and clongenic survival in vitro. Mechanistically,
hPAF1C could promote lung cancer cell proliferation through
regulating c-MYC transcription. Further understanding the details
of the regulation between hPAF1C and c-MYC could be beneficial in