Table 2.

Overview of the different modifications of expression of complement proteins in a tumor context. The upper part of the table summarizes the overexpression of complement proteins described in different cancer types. The overexpression of complement proteins occurs at each step of the complement cascade: classical pathway, lectin pathway, alternative pathway, anaphylatoxins, MAC and regulators. The lower table summarizes the down-regulation of complement proteins described in the literature. The down-regulation of complement proteins involves the classical and alternative pathway, and complement regulators.

Overexpression
Molecule	Type of Cancer	Mechanism of Action	Ref.
C1q	Glioblastoma	Plasma: increased C1q in the sera of patients in comparison with healthy controls.	[72]
C1s	Lung cancer	Plasma: increased levels of C1s in plasma of lung cancer patient in comparison with controls	[73]
	Prostate cancer	Tumor: Up-regulation of C1s expression in prostate tumors compared to matched normal prostate tissues	[74]
C4	Lung cancer	Plasma: elevated C4 levels in cancer patients in comparison to control group	[75]
C4a	Papillary thyroid cancer	Plasma: increased C4a in the sera of patients in comparison with healthy controls.	[76]
C4d	Lung cancer	Bronchial fluid: Higher levels of C4d in cancer patients than patients with control group.	[77]
	Lung cancer	Plasma: Higher levels of C4d in cancer patients than patients with benign nodules.	[25]
C3	Lung cancer	Plasma: elevated C3 levels in cancer patients in comparison to control group	[75]
	Neuroblastoma	Plasma: elevated C3 levels in cancer patients in comparison to healthy donors	[78]
	Pancreatic ductal adenocarcinoma	Tumor: Higher levels of C3 protein in cancerous tissues than in adjacent normal pancreatic tissues	[79]
	Pancreatic cancer	Tumor: Higher levels of C3 protein in cancerous tissues than in normal pancreatic tissues	[80]
C3a	Esophageal cancer	Plasma: Higher C3a levels in patients than healthy donors	[81]
C3a desArg	Breast cancer	Plasma: Higher C3a desArg level in patients than healthy donors	[82]
C5a	Non-small cell lung cancer	Plasma: Higher C3a levels in patients than healthy donors	[47]
C5aR1	Gastric cancer	Tumor: higher expression of C5aR1 in gastric tumoral tissues than in adjacent non-tumoral tissues	[83]
FH	Squamous lung cancer	Plasma: Up-regulation of FH in uranium exposed miners in comparison with exposed miners without lung disease	[84]
	Lung cancer	Bronchoalveolar lavage: Higher concentration of factor H in lung cancer patients than controls	[85]
	Cutaneous squamous cell carcinoma	Tumor: FH is more expressed in invasive cSCC than normal skin or in situ cSCC.	[56]
	Bladder cancer	Urines: FH and FH related protein are markers for bladder cancer	[86,87]
FI	Cutaneous squamous cell carcinoma	Tumor: FI is more expressed in invasive cSCC than normal skin or in situ cSCC.	[28]
C9	Squamous cell lung cancer	Plasma: C9 and its fucosylated form are significantly higher in SQLC patients, as compared to healthy control	[88]
CD46	Colon cancer	Tumor: CD46 is higher in colon cancer tissues compared with normal adjacent colon tissues	[89]
CD55	Colon cancer	Tumor: CD55 is higher in colon cancer tissues compared with normal adjacent colon tissues	[89]
CD59	Colon cancer	Tumor: CD59 is higher in colon cancer tissues compared with normal adjacent colon tissues	[89]
MASP2	Ovarian tumor	Tumor: MASP2 gene expression is higher with ovarian cancer compared with controls	[90]
MBL	Colon tumor	Plasma: MBL2 levels increases in patients compared to healthy blood donors.	[91]
	Ovarian tumor	Tumor: MBL2 gene expression is higher with ovarian cancer compared with controls	[90]
Underexpression
C1s	Ovarian cancer	Tumor: Down-regulation of C1s mRNA in ovarian tumor vs healthy control	[92]
	Ovarian cancer	Tumor: Down-regulation of C1s expression in stage III serous ovarian carcinoma compared to normal tissue	[93]
	Lung cancer	Tumor: decrease expression in lung tumor tissues in comparison with peritumoral tissues	[73]
C4BP	Ovarian cancer	Tumor: Down-regulation of C4BPA mRNA in ovarian tumor vs healthy control	[92]
C7	Ovarian cancer	Tumor: Down-regulation of C7 mRNA in ovarian tumor vs healthy control	[92]
FB	Glioblastoma	Plasma: decreased level of FB in GBM	[72]
FI	Gastric cancer	Plasma: FI is significantly lower in gastric cancer sera compared to normal sera. Declining expression with the advanced pTNM stage from stage I to IV of gastric cancer patients	[94]
FH	Colon cancer	Plasma: Decrease in FH protein level in the serum of colorectal cancer patients vs. normal control	[95]
	Ovarian cancer	Tumor: Down-regulation of FH mRNA in ovarian tumor vs healthy control	[92]
CD55	Ovarian cancer	Tumor: Lower expression of CD55 in ovarian cancer than in control	[30]